Cold dark matter and degree-scale cosmic microwave background anisotropy statistics after COBE

NASA Technical Reports Server (NTRS)

Gorski, Krzysztof M.; Stompor, Radoslaw; Juszkiewicz, Roman

1993-01-01

We conduct a Monte Carlo simulation of the cosmic microwave background (CMB) anisotropy in the UCSB South Pole 1991 degree-scale experiment. We examine cold dark matter cosmology with large-scale structure seeded by the Harrison-Zel'dovich hierarchy of Gaussian-distributed primordial inhomogeneities normalized to the COBE-DMR measurement of large-angle CMB anisotropy. We find it statistically implausible (in the sense of low cumulative probability F lower than 5 percent, of not measuring a cosmological delta-T/T signal) that the degree-scale cosmological CMB anisotropy predicted in such models could have escaped a detection at the level of sensitivity achieved in the South Pole 1991 experiment.

Can cosmic shear shed light on low cosmic microwave background multipoles?

PubMed

Kesden, Michael; Kamionkowski, Marc; Cooray, Asantha

2003-11-28

The lowest multipole moments of the cosmic microwave background (CMB) are smaller than expected for a scale-invariant power spectrum. One possible explanation is a cutoff in the primordial power spectrum below a comoving scale of k(c) approximately equal to 5.0 x 10(-4) Mpc(-1). Such a cutoff would increase significantly the cross correlation between the large-angle CMB and cosmic-shear patterns. The cross correlation may be detectable at >2sigma which, combined with the low CMB moments, may tilt the balance between a 2sigma result and a firm detection of a large-scale power-spectrum cutoff. The cutoff also increases the large-angle cross correlation between the CMB and the low-redshift tracers of the mass distribution.

Will COBE challenge the inflationary paradigm - Cosmic microwave background anisotropies versus large-scale streaming motions revisited

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gorski, K.M.

1991-03-01

The relation between cosmic microwave background (CMB) anisotropies and large-scale galaxy streaming motions is examined within the framework of inflationary cosmology. The minimal Sachs and Wolfe (1967) CMB anisotropies at large angular scales in the models with initial Harrison-Zel'dovich spectrum of inhomogeneity normalized to the local large-scale bulk flow, which are independent of the Hubble constant and specific nature of dark matter, are found to be within the anticipated ultimate sensitivity limits of COBE's Differential Microwave Radiometer experiment. For example, the most likely value of the quadrupole coefficient is predicted to be a2 not less than 7 x 10 tomore » the -6th, where equality applies to the limiting minimal model. If (1) COBE's DMR instruments perform well throughout the two-year period; (2) the anisotropy data are not marred by the systematic errors; (3) the large-scale motions retain their present observational status; (4) there is no statistical conspiracy in a sense of the measured bulk flow being of untypically high and the large-scale anisotropy of untypically low amplitudes; and (5) the low-order multipoles in the all-sky primordial fireball temperature map are not detected, the inflationary paradigm will have to be questioned. 19 refs.« less

A correlation between the cosmic microwave background and large-scale structure in the Universe.

PubMed

Boughn, Stephen; Crittenden, Robert

2004-01-01

Observations of distant supernovae and the fluctuations in the cosmic microwave background (CMB) indicate that the expansion of the Universe may be accelerating under the action of a 'cosmological constant' or some other form of 'dark energy'. This dark energy now appears to dominate the Universe and not only alters its expansion rate, but also affects the evolution of fluctuations in the density of matter, slowing down the gravitational collapse of material (into, for example, clusters of galaxies) in recent times. Additional fluctuations in the temperature of CMB photons are induced as they pass through large-scale structures and these fluctuations are necessarily correlated with the distribution of relatively nearby matter. Here we report the detection of correlations between recent CMB data and two probes of large-scale structure: the X-ray background and the distribution of radio galaxies. These correlations are consistent with those predicted by dark energy, indicating that we are seeing the imprint of dark energy on the growth of structure in the Universe.

International Large-Scale Assessments: What Uses, What Consequences?

ERIC Educational Resources Information Center

Johansson, Stefan

2016-01-01

Background: International large-scale assessments (ILSAs) are a much-debated phenomenon in education. Increasingly, their outcomes attract considerable media attention and influence educational policies in many jurisdictions worldwide. The relevance, uses and consequences of these assessments are often the focus of research scrutiny. Whilst some…

Inflationary tensor perturbations after BICEP2.

PubMed

Caligiuri, Jerod; Kosowsky, Arthur

2014-05-16

The measurement of B-mode polarization of the cosmic microwave background at large angular scales by the BICEP experiment suggests a stochastic gravitational wave background from early-Universe inflation with a surprisingly large amplitude. The power spectrum of these tensor perturbations can be probed both with further measurements of the microwave background polarization at smaller scales and also directly via interferometry in space. We show that sufficiently sensitive high-resolution B-mode measurements will ultimately have the ability to test the inflationary consistency relation between the amplitude and spectrum of the tensor perturbations, confirming their inflationary origin. Additionally, a precise B-mode measurement of the tensor spectrum will predict the tensor amplitude on solar system scales to 20% accuracy for an exact power-law tensor spectrum, so a direct detection will then measure the running of the tensor spectral index to high precision.

Cold dark matter confronts the cosmic microwave background - Large-angular-scale anisotropies in Omega sub 0 + lambda 1 models

NASA Technical Reports Server (NTRS)

Gorski, Krzysztof M.; Silk, Joseph; Vittorio, Nicola

1992-01-01

A new technique is used to compute the correlation function for large-angle cosmic microwave background anisotropies resulting from both the space and time variations in the gravitational potential in flat, vacuum-dominated, cold dark matter cosmological models. Such models with Omega sub 0 of about 0.2, fit the excess power, relative to the standard cold dark matter model, observed in the large-scale galaxy distribution and allow a high value for the Hubble constant. The low order multipoles and quadrupole anisotropy that are potentially observable by COBE and other ongoing experiments should definitively test these models.

Modified dispersion relations, inflation, and scale invariance

NASA Astrophysics Data System (ADS)

Bianco, Stefano; Friedhoff, Victor Nicolai; Wilson-Ewing, Edward

2018-02-01

For a certain type of modified dispersion relations, the vacuum quantum state for very short wavelength cosmological perturbations is scale-invariant and it has been suggested that this may be the source of the scale-invariance observed in the temperature anisotropies in the cosmic microwave background. We point out that for this scenario to be possible, it is necessary to redshift these short wavelength modes to cosmological scales in such a way that the scale-invariance is not lost. This requires nontrivial background dynamics before the onset of standard radiation-dominated cosmology; we demonstrate that one possible solution is inflation with a sufficiently large Hubble rate, for this slow roll is not necessary. In addition, we also show that if the slow-roll condition is added to inflation with a large Hubble rate, then for any power law modified dispersion relation quantum vacuum fluctuations become nearly scale-invariant when they exit the Hubble radius.

The ellipsoidal universe in the Planck satellite era

NASA Astrophysics Data System (ADS)

Cea, Paolo

2014-06-01

Recent Planck data confirm that the cosmic microwave background displays the quadrupole power suppression together with large-scale anomalies. Progressing from previous results, that focused on the quadrupole anomaly, we strengthen the proposal that the slightly anisotropic ellipsoidal universe may account for these anomalies. We solved at large scales the Boltzmann equation for the photon distribution functions by taking into account both the effects of the inflation produced primordial scalar perturbations and the anisotropy of the geometry in the ellipsoidal universe. We showed that the low quadrupole temperature correlations allowed us to fix the eccentricity at decoupling, edec = (0.86 ± 0.14) 10-2, and to constraint the direction of the symmetry axis. We found that the anisotropy of the geometry of the universe contributes only to the large-scale temperature anisotropies without affecting the higher multipoles of the angular power spectrum. Moreover, we showed that the ellipsoidal geometry of the universe induces sizeable polarization signal at large scales without invoking the reionization scenario. We explicitly evaluated the quadrupole TE and EE correlations. We found an average large-scale polarization ΔTpol = (1.20 ± 0.38) μK. We point out that great care is needed in the experimental determination of the large-scale polarization correlations since the average temperature polarization could be misinterpreted as foreground emission leading, thereby, to a considerable underestimate of the cosmic microwave background polarization signal.

Differential Relations between Facets of Complex Problem Solving and Students' Immigration Background

ERIC Educational Resources Information Center

Sonnleitner, Philipp; Brunner, Martin; Keller, Ulrich; Martin, Romain

2014-01-01

Whereas the assessment of complex problem solving (CPS) has received increasing attention in the context of international large-scale assessments, its fairness in regard to students' cultural background has gone largely unexplored. On the basis of a student sample of 9th-graders (N = 299), including a representative number of immigrant students (N…

Large-angle cosmic microwave background anisotropies in an open universe

NASA Technical Reports Server (NTRS)

Kamionkowski, Marc; Spergel, David N.

1994-01-01

If the universe is open, scales larger than the curvature scale may be probed by observation of large-angle fluctuations in the cosmic microwave background (CMB). We consider primordial adiabatic perturbations and discuss power spectra that are power laws in volume, wavelength, and eigenvalue of the Laplace operator. Such spectra may have arisen if, for example, the universe underwent a period of `frustated' inflation. The resulting large-angle anisotropies of the CMB are computed. The amplitude generally increases as Omega is decreased but decreases as h is increased. Interestingly enough, for all three Ansaetze, anisotropies on angular scales larger than the curvature scale are suppressed relative to the anisotropies on scales smaller than the curvature scale, but cosmic variance makes discrimination between various models difficult. Models with 0.2 approximately less than Omega h approximately less than 0.3 appear compatible with CMB fluctuations detected by Cosmic Background Explorer Satellite (COBE) and the Tenerife experiment and with the amplitude and spectrum of fluctuations of galaxy counts in the APM, CfA, and 1.2 Jy IRAS surveys. COBE normalization for these models yields sigma(sub 8) approximately = 0.5 - 0.7. Models with smaller values of Omega h when normalized to COBE require bias factors in excess of 2 to be compatible with the observed galaxy counts on the 8/h Mpc scale. Requiring that the age of the universe exceed 10 Gyr implies that Omega approximately greater than 0.25, while requiring that from the last-scattering term in the Sachs-Wolfe formula, large-angle anisotropies come primarily from the decay of potential fluctuations at z approximately less than 1/Omega. Thus, if the universe is open, COBE has been detecting temperature fluctuations produced at moderate redshift rather than at z approximately 1300.

Model-independent test for scale-dependent non-Gaussianities in the cosmic microwave background.

PubMed

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.

An Alternative Way to Model Population Ability Distributions in Large-Scale Educational Surveys

ERIC Educational Resources Information Center

Wetzel, Eunike; Xu, Xueli; von Davier, Matthias

2015-01-01

In large-scale educational surveys, a latent regression model is used to compensate for the shortage of cognitive information. Conventionally, the covariates in the latent regression model are principal components extracted from background data. This operational method has several important disadvantages, such as the handling of missing data and…

Using d15N of Chironomidae to help assess lake condition and possible stressors in EPA?s National Lakes Assessment.

EPA Science Inventory

Background/Questions/Methods As interest in continental-scale ecology increases to address large-scale ecological problems, ecologists need indicators of complex processes that can be collected quickly at many sites across large areas. We are exploring the utility of stable isot...

The Neutral Islands during the Late Epoch of Reionization

NASA Astrophysics Data System (ADS)

Xu, Yidong; Yue, Bin; Chen, Xuelei

2018-05-01

The large-scale structure of the ionization field during the epoch of reionization (EoR) can be modeled by the excursion set theory. While the growth of ionized regions during the early stage are described by the ``bubble model'', the shrinking process of neutral regions after the percolation of the ionized region calls for an ``island model''. An excursion set based analytical model and a semi-numerical code (islandFAST) have been developed. The ionizing background and the bubbles inside the islands are also included in the treatment. With two kinds of absorbers of ionizing photons, i.e. the large-scale under-dense neutral islands and the small-scale over-dense clumps, the ionizing background are self-consistently evolved in the model.

Compensation for large tensor modes with iso-curvature perturbations in CMB anisotropies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kawasaki, Masahiro; Yokoyama, Shuichiro, E-mail: kawasaki@icrr.u-tokyo.ac.jp, E-mail: shu@icrr.u-tokyo.ac.jp

Recently, BICEP2 has reported the large tensor-to-scalar ratio r = 0.2{sup +0.07}{sub −0.05} from the observation of the cosmic microwave background (CMB) B-mode at degree-scales. Since tensor modes induce not only CMB B-mode but also the temperature fluctuations on large scales, to realize the consistent temperature fluctuations with the Planck result we should consider suppression of scalar perturbations on corresponding large scales. To realize such a suppression, we consider anti-correlated iso-curvature perturbations which could be realized in the simple curvaton model.

Home Language and Language Proficiency; A Large-Scale Longitudinal Study in Dutch Primary Schools.

ERIC Educational Resources Information Center

Driessen, Geert; van der Slik, Frans; De Bot, Kees

2002-01-01

Reports on a large-scale longitudinal study into the development of language proficiency of Dutch primary school children aged 7-10. Data on language proficiency and a range of background variables were analyzed. Results suggest that while immigrant children develop their language skill in Dutch considerably over 2 years, they are nonetheless…

Readout circuit with novel background suppression for long wavelength infrared focal plane arrays

NASA Astrophysics Data System (ADS)

Xie, L.; Xia, X. J.; Zhou, Y. F.; Wen, Y.; Sun, W. F.; Shi, L. X.

2011-02-01

In this article, a novel pixel readout circuit using a switched-capacitor integrator mode background suppression technique is presented for long wavelength infrared focal plane arrays. This circuit can improve dynamic range and signal-to-noise ratio by suppressing the large background current during integration. Compared with other background suppression techniques, the new background suppression technique is less sensitive to the process mismatch and has no additional shot noise. The proposed circuit is theoretically analysed and simulated while taking into account the non-ideal characteristics. The result shows that the background suppression non-uniformity is ultra-low even for a large process mismatch. The background suppression non-uniformity of the proposed circuit can also remain very small with technology scaling.

Implications of a primordial origin for the dispersion in D/H in quasar absorption systems

PubMed Central

Copi, Craig J.; Olive, Keith A.; Schramm, David N.

1998-01-01

We explore the difficulties with a primordial origin of variations of D/H in quasar absorption systems. In particular we examine options such as a very large-scale inhomogeneity in the baryon content of the universe. We show that very large-scale (much larger than 1 Mpc) isocurvature perturbations are excluded by current cosmic microwave background observations. Smaller-scale ad hoc perturbations (∼1 Mpc) still may lead to a large dispersion in primordial abundances but are subject to other constraints. PMID:9501162

Implications of a primordial origin for the dispersion in D/H in quasar absorption systems.

PubMed

Copi, C J; Olive, K A; Schramm, D N

1998-03-17

We explore the difficulties with a primordial origin of variations of D/H in quasar absorption systems. In particular we examine options such as a very large-scale inhomogeneity in the baryon content of the universe. We show that very large-scale (much larger than 1 Mpc) isocurvature perturbations are excluded by current cosmic microwave background observations. Smaller-scale ad hoc perturbations (approximately 1 Mpc) still may lead to a large dispersion in primordial abundances but are subject to other constraints.

Impacts of different characterizations of large-scale background on simulated regional-scale ozone over the continental United States

EPA Science Inventory

This study analyzes simulated regional-scale ozone burdens both near the surface and aloft, estimates process contributions to these burdens, and calculates the sensitivity of the simulated regional-scale ozone burden to several key model inputs with a particular emphasis on boun...

The influence of super-horizon scales on cosmological observables generated during inflation

NASA Astrophysics Data System (ADS)

Matarrese, Sabino; Musso, Marcello A.; Riotto, Antonio

2004-05-01

Using the techniques of out-of-equilibrium field theory, we study the influence on properties of cosmological perturbations generated during inflation on observable scales coming from fluctuations corresponding today to scales much bigger than the present Hubble radius. We write the effective action for the coarse grained inflaton perturbations, integrating out the sub-horizon modes, which manifest themselves as a coloured noise and lead to memory effects. Using the simple model of a scalar field with cubic self-interactions evolving in a fixed de Sitter background, we evaluate the two- and three-point correlation function on observable scales. Our basic procedure shows that perturbations do preserve some memory of the super-horizon scale dynamics, in the form of scale dependent imprints in the statistical moments. In particular, we find a blue tilt of the power spectrum on large scales, in agreement with the recent results of the WMAP collaboration which show a suppression of the lower multipoles in the cosmic microwave background anisotropies, and a substantial enhancement of the intrinsic non-Gaussianity on large scales.

The cosmic microwave background radiation

NASA Technical Reports Server (NTRS)

Silk, Joseph

1992-01-01

A review the implications of the spectrum and anisotropy of the cosmic microwave background for cosmology. Thermalization and processes generating spectral distortions are discussed. Anisotropy predictions are described and compared with observational constraints. If the evidence for large-scale power in the galaxy distribution in excess of that predicted by the cold dark matter model is vindicated, and the observed structure originated via gravitational instabilities of primordial density fluctuations, the predicted amplitude of microwave background anisotropies on angular scales of a degree and larger must be at least several parts in 10 exp 6.

Formation of large-scale structure from cosmic strings and massive neutrinos

NASA Technical Reports Server (NTRS)

Scherrer, Robert J.; Melott, Adrian L.; Bertschinger, Edmund

1989-01-01

Numerical simulations of large-scale structure formation from cosmic strings and massive neutrinos are described. The linear power spectrum in this model resembles the cold-dark-matter power spectrum. Galaxy formation begins early, and the final distribution consists of isolated density peaks embedded in a smooth background, leading to a natural bias in the distribution of luminous matter. The distribution of clustered matter has a filamentary appearance with large voids.

Large scale anomalies in the microwave background: causation and correlation.

PubMed

Aslanyan, Grigor; Easther, Richard

2013-12-27

Most treatments of large scale anomalies in the microwave sky are a posteriori, with unquantified look-elsewhere effects. We contrast these with physical models of specific inhomogeneities in the early Universe which can generate these apparent anomalies. Physical models predict correlations between candidate anomalies and the corresponding signals in polarization and large scale structure, reducing the impact of cosmic variance. We compute the apparent spatial curvature associated with large-scale inhomogeneities and show that it is typically small, allowing for a self-consistent analysis. As an illustrative example we show that a single large plane wave inhomogeneity can contribute to low-l mode alignment and odd-even asymmetry in the power spectra and the best-fit model accounts for a significant part of the claimed odd-even asymmetry. We argue that this approach can be generalized to provide a more quantitative assessment of potential large scale anomalies in the Universe.

Anisotropies of the cosmic microwave background in nonstandard cold dark matter models

NASA Technical Reports Server (NTRS)

Vittorio, Nicola; Silk, Joseph

1992-01-01

Small angular scale cosmic microwave anisotropies in flat, vacuum-dominated, cold dark matter cosmological models which fit large-scale structure observations and are consistent with a high value for the Hubble constant are reexamined. New predictions for CDM models in which the large-scale power is boosted via a high baryon content and low H(0) are presented. Both classes of models are consistent with current limits: an improvement in sensitivity by a factor of about 3 for experiments which probe angular scales between 7 arcmin and 1 deg is required, in the absence of very early reionization, to test boosted CDM models for large-scale structure formation.

Distortion of the cosmic background radiation by superconducting strings

NASA Technical Reports Server (NTRS)

Ostriker, J. P.; Thompson, C.

1987-01-01

Superconducting cosmic strings can be significant energy sources, keeping the universe ionized past the commonly assumed epoch of recombination. As a result, the spectrum of the cosmic background radiation is distorted in the presence of heated primordial gas via the Suniaev-Zel'dovich effect. Thiis distortion can be relatively large: the Compton y parameter attains a maximum in the range 0.001-0.005, with these values depending on the mass scale of the string. A significant contribution to y comes from loops decaying at high redshift when the universe is optically thick to Thomson scattering. Moreover, the isotropic spectral distortion is large compared to fluctuations at all angular scales.

Anisotropy of the Cosmic Microwave Background Radiation on Large and Medium Angular Scales

NASA Technical Reports Server (NTRS)

Houghton, Anthony; Timbie, Peter

1998-01-01

This grant has supported work at Brown University on measurements of the 2.7 K Cosmic Microwave Background Radiation (CMB). The goal has been to characterize the spatial variations in the temperature of the CMB in order to understand the formation of large-scale structure in the universe. We have concurrently pursued two measurements using millimeter-wave telescopes carried aloft by scientific balloons. Both systems operate over a range of wavelengths, chosen to allow spectral removal of foreground sources such as the atmosphere, Galaxy, etc. The angular resolution of approx. 25 arcminutes is near the angular scale at which the most structure is predicted by current models to be visible in the CMB angular power spectrum. The main goal is to determine the angular scale of this structure; in turn we can infer the density parameter, Omega, for the universe as well as other cosmological parameters, such as the Hubble constant.

Changeable camouflage: how well can flounder resemble the colour and spatial scale of substrates in their natural habitats?

PubMed Central

Akkaynak, Derya; Siemann, Liese A.; Barbosa, Alexandra

2017-01-01

Flounder change colour and pattern for camouflage. We used a spectrometer to measure reflectance spectra and a digital camera to capture body patterns of two flounder species camouflaged on four natural backgrounds of different spatial scale (sand, small gravel, large gravel and rocks). We quantified the degree of spectral match between flounder and background relative to the situation of perfect camouflage in which flounder and background were assumed to have identical spectral distribution. Computations were carried out for three biologically relevant observers: monochromatic squid, dichromatic crab and trichromatic guitarfish. Our computations present a new approach to analysing datasets with multiple spectra that have large variance. Furthermore, to investigate the spatial match between flounder and background, images of flounder patterns were analysed using a custom program originally developed to study cuttlefish camouflage. Our results show that all flounder and background spectra fall within the same colour gamut and that, in terms of different observer visual systems, flounder matched most substrates in luminance and colour contrast. Flounder matched the spatial scales of all substrates except for rocks. We discuss findings in terms of flounder biology; furthermore, we discuss our methodology in light of hyperspectral technologies that combine high-resolution spectral and spatial imaging. PMID:28405370

Changeable camouflage: how well can flounder resemble the colour and spatial scale of substrates in their natural habitats?

PubMed

Akkaynak, Derya; Siemann, Liese A; Barbosa, Alexandra; Mäthger, Lydia M

2017-03-01

Flounder change colour and pattern for camouflage. We used a spectrometer to measure reflectance spectra and a digital camera to capture body patterns of two flounder species camouflaged on four natural backgrounds of different spatial scale (sand, small gravel, large gravel and rocks). We quantified the degree of spectral match between flounder and background relative to the situation of perfect camouflage in which flounder and background were assumed to have identical spectral distribution. Computations were carried out for three biologically relevant observers: monochromatic squid, dichromatic crab and trichromatic guitarfish. Our computations present a new approach to analysing datasets with multiple spectra that have large variance. Furthermore, to investigate the spatial match between flounder and background, images of flounder patterns were analysed using a custom program originally developed to study cuttlefish camouflage. Our results show that all flounder and background spectra fall within the same colour gamut and that, in terms of different observer visual systems, flounder matched most substrates in luminance and colour contrast. Flounder matched the spatial scales of all substrates except for rocks. We discuss findings in terms of flounder biology; furthermore, we discuss our methodology in light of hyperspectral technologies that combine high-resolution spectral and spatial imaging.

Just enough inflation: power spectrum modifications at large scales

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cicoli, Michele; Downes, Sean; Dutta, Bhaskar

2014-12-01

We show that models of 'just enough' inflation, where the slow-roll evolution lasted only 50- 60 e-foldings, feature modifications of the CMB power spectrum at large angular scales. We perform a systematic analytic analysis in the limit of a sudden transition between any possible non-slow-roll background evolution and the final stage of slow-roll inflation. We find a high degree of universality since most common backgrounds like fast-roll evolution, matter or radiation-dominance give rise to a power loss at large angular scales and a peak together with an oscillatory behaviour at scales around the value of the Hubble parameter at themore » beginning of slow-roll inflation. Depending on the value of the equation of state parameter, different pre-inflationary epochs lead instead to an enhancement of power at low ℓ, and so seem disfavoured by recent observational hints for a lack of CMB power at ℓ∼< 40. We also comment on the importance of initial conditions and the possibility to have multiple pre-inflationary stages.« less

Blue spectra of Kalb-Ramond axions and fully anisotropic string cosmologies

NASA Astrophysics Data System (ADS)

Giovannini, Massimo

1999-03-01

The inhomogeneities associated with massless Kalb-Ramond axions can be amplified not only in isotropic (four-dimensional) string cosmological models but also in the fully anisotropic case. If the background geometry is isotropic, the axions (which are not part of the homogeneous background) develop outside the horizon, the growing modes leading, ultimately, to logarithmic energy spectra which are ``red'' in frequency and increase at large distance scales. We show that this conclusion can be avoided not only in the case of higher dimensional backgrounds with contracting internal dimensions but also in the case of string cosmological scenarios which are completely anisotropic in four dimensions. In this case the logarithmic energy spectra turn out to be ``blue'' in frequency and, consequently, decreasing at large distance scales. We elaborate on anisotropic dilaton-driven models and we argue that, incidentally, the background models leading to blue (or flat) logarithmic energy spectra for axionic fluctuations are likely to be isotropized by the effect of string tension corrections.

The Cosmology Large Angular Scale Surveyor (CLASS): 38 GHz Detector Array of Bolometric Polarimeters

NASA Technical Reports Server (NTRS)

Appel, John W.; Ali, Aamir; Amiri, Mandana; Araujo, Derek; Bennett, Charles L.; Boone, Fletcher; Chan, Manwei; Cho, Hsiao-Mei; Chuss, David T.; Colazo, Felipe;

The cosmology large angular scale surveyor (CLASS): 38-GHz detector array of bolometric polarimeters

NASA Astrophysics Data System (ADS)

Appel, John W.; Ali, Aamir; Amiri, Mandana; Araujo, Derek; Bennet, Charles L.; Boone, Fletcher; Chan, Manwei; Cho, Hsiao-Mei; Chuss, David T.; Colazo, Felipe; Crowe, Erik; Denis, Kevin; Dünner, Rolando; Eimer, Joseph; Essinger-Hileman, Thomas; Gothe, Dominik; Halpern, Mark; Harrington, Kathleen; Hilton, Gene; Hinshaw, Gary F.; Huang, Caroline; Irwin, Kent; Jones, Glenn; Karakula, John; Kogut, Alan J.; Larson, David; Limon, Michele; Lowry, Lindsay; Marriage, Tobias; Mehrle, Nicholas; Miller, Amber D.; Miller, Nathan; Moseley, Samuel H.; Novak, Giles; Reintsema, Carl; Rostem, Karwan; Stevenson, Thomas; Towner, Deborah; U-Yen, Kongpop; Wagner, Emily; Watts, Duncan; Wollack, Edward; Xu, Zhilei; Zeng, Lingzhen

2014-07-01

The Cosmology Large Angular Scale Surveyor (CLASS) experiment aims to map the polarization of the Cosmic Microwave Background (CMB) at angular scales larger than a few degrees. Operating from Cerro Toco in the Atacama Desert of Chile, it will observe over 65% of the sky at 38, 93, 148, and 217 GHz. In this paper we discuss the design, construction, and characterization of the CLASS 38 GHz detector focal plane, the first ever Q-band bolometric polarimeter array.

Scientific results from the Cosmic Background Explorer (COBE)

PubMed Central

Bennett, C. L.; Boggess, N. W.; Cheng, E. S.; Hauser, M. G.; Kelsall, T.; Mather, J. C.; Moseley, S. H.; Murdock, T. L.; Shafer, R. A.; Silverberg, R. F.; Smoot, G. F.; Weiss, R.; Wright, E. L.

1993-01-01

The National Aeronautics and Space Administration (NASA) has flown the COBE satellite to observe the Big Bang and the subsequent formation of galaxies and large-scale structure. Data from the Far-Infrared Absolute Spectrophotometer (FIRAS) show that the spectrum of the cosmic microwave background is that of a black body of temperature T = 2.73 ± 0.06 K, with no deviation from a black-body spectrum greater than 0.25% of the peak brightness. The data from the Differential Microwave Radiometers (DMR) show statistically significant cosmic microwave background anisotropy, consistent with a scale-invariant primordial density fluctuation spectrum. Measurements from the Diffuse Infrared Background Experiment (DIRBE) provide new conservative upper limits to the cosmic infrared background. Extensive modeling of solar system and galactic infrared foregrounds is required for further improvement in the cosmic infrared background limits. PMID:11607383

Resurrecting hot dark matter - Large-scale structure from cosmic strings and massive neutrinos

NASA Technical Reports Server (NTRS)

Scherrer, Robert J.

1988-01-01

These are the results of a numerical simulation of the formation of large-scale structure from cosmic-string loops in a universe dominated by massive neutrinos (hot dark matter). This model has several desirable features. The final matter distribution contains isolated density peaks embedded in a smooth background, producing a natural bias in the distribution of luminous matter. Because baryons can accrete onto the cosmic strings before the neutrinos, the galaxies will have baryon cores and dark neutrino halos. Galaxy formation in this model begins much earlier than in random-phase models. On large scales the distribution of clustered matter visually resembles the CfA survey, with large voids and filaments.

Exploring the Large Scale Anisotropy in the Cosmic Microwave Background Radiation at 170 GHz

NASA Astrophysics Data System (ADS)

Ganga, Kenneth Matthew

1994-01-01

In this thesis, data from the Far Infra-Red Survey (FIRS), a balloon-borne experiment designed to measure the large scale anisotropy in the cosmic microwave background radiation, are analyzed. The FIRS operates in four frequency bands at 170, 280, 480, and 670 GHz, using an approximately Gaussian beam with a 3.8 deg full-width-at-half-maximum. A cross-correlation with the COBE/DMR first-year maps yields significant results, confirming the DMR detection of anisotropy in the cosmic microwave background radiation. Analysis of the FIRS data alone sets bounds on the amplitude of anisotropy under the assumption that the fluctuations are described by a Harrison-Peebles-Zel'dovich spectrum and further analysis sets limits on the index of the primordial density fluctuations for an Einstein-DeSitter universe. Galactic dust emission is discussed and limits are set on the magnitude of possible systematic errors in the measurement.

A resource of large-scale molecular markers for monitoring Agropyron cristatum chromatin introgression in wheat background based on transcriptome sequences.

PubMed

Zhang, Jinpeng; Liu, Weihua; Lu, Yuqing; Liu, Qunxing; Yang, Xinming; Li, Xiuquan; Li, Lihui

2017-09-20

Agropyron cristatum is a wild grass of the tribe Triticeae and serves as a gene donor for wheat improvement. However, very few markers can be used to monitor A. cristatum chromatin introgressions in wheat. Here, we reported a resource of large-scale molecular markers for tracking alien introgressions in wheat based on transcriptome sequences. By aligning A. cristatum unigenes with the Chinese Spring reference genome sequences, we designed 9602 A. cristatum expressed sequence tag-sequence-tagged site (EST-STS) markers for PCR amplification and experimental screening. As a result, 6063 polymorphic EST-STS markers were specific for the A. cristatum P genome in the single-receipt wheat background. A total of 4956 randomly selected polymorphic EST-STS markers were further tested in eight wheat variety backgrounds, and 3070 markers displaying stable and polymorphic amplification were validated. These markers covered more than 98% of the A. cristatum genome, and the marker distribution density was approximately 1.28 cM. An application case of all EST-STS markers was validated on the A. cristatum 6 P chromosome. These markers were successfully applied in the tracking of alien A. cristatum chromatin. Altogether, this study provided a universal method of large-scale molecular marker development to monitor wild relative chromatin in wheat.

Probing Large-scale Coherence between Spitzer IR and Chandra X-Ray Source-subtracted Cosmic Backgrounds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cappelluti, N.; Urry, M.; Arendt, R.

2017-09-20

We present new measurements of the large-scale clustering component of the cross-power spectra of the source-subtracted Spitzer -IRAC cosmic infrared background and Chandra -ACIS cosmic X-ray background surface brightness fluctuations Our investigation uses data from the Chandra Deep Field South, Hubble Deep Field North, Extended Groth Strip/AEGIS field, and UDS/SXDF surveys, comprising 1160 Spitzer hours and ∼12 Ms of Chandra data collected over a total area of 0.3 deg{sup 2}. We report the first (>5 σ ) detection of a cross-power signal on large angular scales >20″ between [0.5–2] keV and the 3.6 and 4.5 μ m bands, at ∼5more » σ and 6.3 σ significance, respectively. The correlation with harder X-ray bands is marginally significant. Comparing the new observations with existing models for the contribution of the known unmasked source population at z < 7, we find an excess of about an order of magnitude at 5 σ confidence. We discuss possible interpretations for the origin of this excess in terms of the contribution from accreting early black holes (BHs), including both direct collapse BHs and primordial BHs, as well as from scattering in the interstellar medium and intra-halo light.« less

Inflation physics from the cosmic microwave background and large scale structure

NASA Astrophysics Data System (ADS)

Abazajian, K. N.; Arnold, K.; Austermann, J.; Benson, B. A.; Bischoff, C.; Bock, J.; Bond, J. R.; Borrill, J.; Buder, I.; Burke, D. L.; Calabrese, E.; Carlstrom, J. E.; Carvalho, C. S.; Chang, C. L.; Chiang, H. C.; Church, S.; Cooray, A.; Crawford, T. M.; Crill, B. P.; Dawson, K. S.; Das, S.; Devlin, M. J.; Dobbs, M.; Dodelson, S.; Doré, O.; Dunkley, J.; Feng, J. L.; Fraisse, A.; Gallicchio, J.; Giddings, S. B.; Green, D.; Halverson, N. W.; Hanany, S.; Hanson, D.; Hildebrandt, S. R.; Hincks, A.; Hlozek, R.; Holder, G.; Holzapfel, W. L.; Honscheid, K.; Horowitz, G.; Hu, W.; Hubmayr, J.; Irwin, K.; Jackson, M.; Jones, W. C.; Kallosh, R.; Kamionkowski, M.; Keating, B.; Keisler, R.; Kinney, W.; Knox, L.; Komatsu, E.; Kovac, J.; Kuo, C.-L.; Kusaka, A.; Lawrence, C.; Lee, A. T.; Leitch, E.; Linde, A.; Linder, E.; Lubin, P.; Maldacena, J.; Martinec, E.; McMahon, J.; Miller, A.; Mukhanov, V.; Newburgh, L.; Niemack, M. D.; Nguyen, H.; Nguyen, H. T.; Page, L.; Pryke, C.; Reichardt, C. L.; Ruhl, J. E.; Sehgal, N.; Seljak, U.; Senatore, L.; Sievers, J.; Silverstein, E.; Slosar, A.; Smith, K. M.; Spergel, D.; Staggs, S. T.; Stark, A.; Stompor, R.; Vieregg, A. G.; Wang, G.; Watson, S.; Wollack, E. J.; Wu, W. L. K.; Yoon, K. W.; Zahn, O.; Zaldarriaga, M.

2015-03-01

Fluctuations in the intensity and polarization of the cosmic microwave background (CMB) and the large-scale distribution of matter in the universe each contain clues about the nature of the earliest moments of time. The next generation of CMB and large-scale structure (LSS) experiments are poised to test the leading paradigm for these earliest moments-the theory of cosmic inflation-and to detect the imprints of the inflationary epoch, thereby dramatically increasing our understanding of fundamental physics and the early universe. A future CMB experiment with sufficient angular resolution and frequency coverage that surveys at least 1% of the sky to a depth of 1 uK-arcmin can deliver a constraint on the tensor-to-scalar ratio that will either result in a 5 σ measurement of the energy scale of inflation or rule out all large-field inflation models, even in the presence of foregrounds and the gravitational lensing B-mode signal. LSS experiments, particularly spectroscopic surveys such as the Dark Energy Spectroscopic Instrument, will complement the CMB effort by improving current constraints on running of the spectral index by up to a factor of four, improving constraints on curvature by a factor of ten, and providing non-Gaussianity constraints that are competitive with the current CMB bounds.

Inflation Physics from the Cosmic Microwave Background and Large Scale Structure

NASA Technical Reports Server (NTRS)

Abazajian, K.N.; Arnold,K.; Austermann, J.; Benson, B.A.; Bischoff, C.; Bock, J.; Bond, J.R.; Borrill, J.; Buder, I.; Burke, D.L.;

Inflation physics from the cosmic microwave background and large scale structure

DOE PAGES

Abazajian, K. N.; Arnold, K.; Austermann, J.; ...

2014-06-26

Here, fluctuations in the intensity and polarization of the cosmic microwave background (CMB) and the large-scale distribution of matter in the universe each contain clues about the nature of the earliest moments of time. The next generation of CMB and large-scale structure (LSS) experiments are poised to test the leading paradigm for these earliest moments—the theory of cosmic inflation—and to detect the imprints of the inflationary epoch, thereby dramatically increasing our understanding of fundamental physics and the early universe. A future CMB experiment with sufficient angular resolution and frequency coverage that surveys at least 1% of the sky to amore » depth of 1 uK-arcmin can deliver a constraint on the tensor-to-scalar ratio that will either result in a 5σ measurement of the energy scale of inflation or rule out all large-field inflation models, even in the presence of foregrounds and the gravitational lensing B -mode signal. LSS experiments, particularly spectroscopic surveys such as the Dark Energy Spectroscopic Instrument, will complement the CMB effort by improving current constraints on running of the spectral index by up to a factor of four, improving constraints on curvature by a factor of ten, and providing non-Gaussianity constraints that are competitive with the current CMB bounds.« less

Fluctuations in microwave background radiation due to secondary ionization of the intergalactic gas in the universe

NASA Technical Reports Server (NTRS)

Sunyayev, R. A.

1979-01-01

Secondary heating and ionization of the intergalactic gas at redshifts z approximately 10-30 could lead to the large optical depth of the Universe for Thomson scattering and could smooth the primordial fluctuations formed at z approximately 1500. It is shown that the gas motions connected with the large scale density perturbations at z approximately 10-15 must lead to the generation of secondary fluctuations of microwave background. The contribution of the rich clusters of galaxies and young galaxies to the fluctuations of microwave background is also estimated.

The large-scale microwave background anisotropy in decaying particle cosmology

NASA Technical Reports Server (NTRS)

Panek, Miroslaw

1988-01-01

The quadrupole anisotropy of the microwave background radiation in cosmological models with decaying particles is investigated. A conservative upper limit on value of the quadrupole moment combined with other constraints gives an upper limit on the redshift of the decay z(d) of less than 3-6.

Does Family Background Matter for Learning in East Africa?

ERIC Educational Resources Information Center

Jones, Sam; Schipper, Youdi

2015-01-01

The extent to which differences in family background characteristics explain differences in learning outcomes between children captures the extent of equality in educational opportunities. This study uses large-scale data on literacy and numeracy outcomes for children of school age across East Africa (Kenya, Tanzania and Uganda) to investigate the…

The Impact of Missing Background Data on Subpopulation Estimation

ERIC Educational Resources Information Center

Rutkowski, Leslie

2011-01-01

Although population modeling methods are well established, a paucity of literature appears to exist regarding the effect of missing background data on subpopulation achievement estimates. Using simulated data that follows typical large-scale assessment designs with known parameters and a number of missing conditions, this paper examines the extent…

On the Interactions Between Planetary and Mesoscale Dynamics in the Oceans

NASA Astrophysics Data System (ADS)

Grooms, I.; Julien, K. A.; Fox-Kemper, B.

2011-12-01

Multiple-scales asymptotic methods are used to investigate the interaction of planetary and mesoscale dynamics in the oceans. We find three regimes. In the first, the slow, large-scale planetary flow sets up a baroclinically unstable background which leads to vigorous mesoscale eddy generation, but the eddy dynamics do not affect the planetary dynamics. In the second, the planetary flow feels the effects of the eddies, but appears to be unable to generate them. The first two regimes rely on horizontally isotropic large-scale dynamics. In the third regime, large-scale anisotropy, as exists for example in the Antarctic Circumpolar Current and in western boundary currents, allows the large-scale dynamics to both generate and respond to mesoscale eddies. We also discuss how the investigation may be brought to bear on the problem of parameterization of unresolved mesoscale dynamics in ocean general circulation models.

Spectrum of perturbations in anisotropic inflationary universe with vector hair

DOE Office of Scientific and Technical Information (OSTI.GOV)

Himmetoglu, Burak, E-mail: burak@physics.umn.edu

2010-03-01

We study both the background evolution and cosmological perturbations of anisotropic inflationary models supported by coupled scalar and vector fields. The models we study preserve the U(1) gauge symmetry associated with the vector field, and therefore do not possess instabilities associated with longitudinal modes (which instead plague some recently proposed models of vector inflation and curvaton). We first intoduce a model in which the background anisotropy slowly decreases during inflation; we then confirm the stability of the background solution by studying the quadratic action for all the perturbations of the model. We then compute the spectrum of the h{sub ×}more » gravitational wave polarization. The spectrum we find breaks statistical isotropy at the largest scales and reduces to the standard nearly scale invariant form at small scales. We finally discuss the possible relevance of our results to the large scale CMB anomalies.« less

The Explorer of Diffuse Galactic Emission (EDGE): Determination of Large-Scale Structure Evolution from Measurement of the Anisotropy of the Cosmic Infrared Background

NASA Technical Reports Server (NTRS)

Silverberg, R. F.; Cheng, E. S.; Cottingham, D. A.; Fixsen, D. J.; Meyer, S. S.; Wilson, G. W.

2004-01-01

The formation of the first objects, stars and galaxies and their subsequent evolution remain a cosmological unknown. Few observational probes of these processes exist. The Cosmic Infrared Background (CIB) originates from this era, and can provide information to test models of both galaxy evolution and the growth of primordial structure. The Explorer of Diffuse Galactic Emission (EDGE) is a proposed balloon-borne mission designed to measure the spatial fluctuations in the CIB from 200 micrometers to 1 millimeter on 6' to 3 degree scales with 2 microKelvin sensitivity/resolution element. Such measurements would provide a sensitive probe of the large-scale variation in protogalaxy density at redshifts approximately 0.5-3. In this paper, we present the scientific justification for the mission and show a concept for the instrument and observations.

Cosmic microwave background bispectrum from primordial magnetic fields on large angular scales.

PubMed

Seshadri, T R; Subramanian, Kandaswamy

2009-08-21

Primordial magnetic fields lead to non-Gaussian signals in the cosmic microwave background (CMB) even at the lowest order, as magnetic stresses and the temperature anisotropy they induce depend quadratically on the magnetic field. In contrast, CMB non-Gaussianity due to inflationary scalar perturbations arises only as a higher-order effect. We propose a novel probe of stochastic primordial magnetic fields that exploits the characteristic CMB non-Gaussianity that they induce. We compute the CMB bispectrum (b(l1l2l3)) induced by such fields on large angular scales. We find a typical value of l1(l1 + 1)l3(l3 + 1)b(l1l2l3) approximately 10(-22), for magnetic fields of strength B0 approximately 3 nG and with a nearly scale invariant magnetic spectrum. Observational limits on the bispectrum allow us to set upper limits on B0 approximately 35 nG.

IslandFAST: A Semi-numerical Tool for Simulating the Late Epoch of Reionization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Yidong; Chen, Xuelei; Yue, Bin

2017-08-01

We present the algorithm and main results of our semi-numerical simulation, islandFAST, which was developed from 21cmFAST and designed for the late stage of reionization. The islandFAST simulation predicts the evolution and size distribution of the large-scale underdense neutral regions (neutral islands), and we find that the late Epoch of Reionization proceeds very fast, showing a characteristic scale of the neutral islands at each redshift. Using islandFAST, we compare the impact of two types of absorption systems, i.e., the large-scale underdense neutral islands versus small-scale overdense absorbers, in regulating the reionization process. The neutral islands dominate the morphology of themore » ionization field, while the small-scale absorbers dominate the mean-free path of ionizing photons, and also delay and prolong the reionization process. With our semi-numerical simulation, the evolution of the ionizing background can be derived self-consistently given a model for the small absorbers. The hydrogen ionization rate of the ionizing background is reduced by an order of magnitude in the presence of dense absorbers.« less

The Large-scale Structure of the Universe: Probes of Cosmology and Structure Formation

NASA Astrophysics Data System (ADS)

Noh, Yookyung

The usefulness of large-scale structure as a probe of cosmology and structure formation is increasing as large deep surveys in multi-wavelength bands are becoming possible. The observational analysis of large-scale structure guided by large volume numerical simulations are beginning to offer us complementary information and crosschecks of cosmological parameters estimated from the anisotropies in Cosmic Microwave Background (CMB) radiation. Understanding structure formation and evolution and even galaxy formation history is also being aided by observations of different redshift snapshots of the Universe, using various tracers of large-scale structure. This dissertation work covers aspects of large-scale structure from the baryon acoustic oscillation scale, to that of large scale filaments and galaxy clusters. First, I discuss a large- scale structure use for high precision cosmology. I investigate the reconstruction of Baryon Acoustic Oscillation (BAO) peak within the context of Lagrangian perturbation theory, testing its validity in a large suite of cosmological volume N-body simulations. Then I consider galaxy clusters and the large scale filaments surrounding them in a high resolution N-body simulation. I investigate the geometrical properties of galaxy cluster neighborhoods, focusing on the filaments connected to clusters. Using mock observations of galaxy clusters, I explore the correlations of scatter in galaxy cluster mass estimates from multi-wavelength observations and different measurement techniques. I also examine the sources of the correlated scatter by considering the intrinsic and environmental properties of clusters.

Large-scale anisotropy in the extragalactic gamma-ray background as a probe for cosmological antimatter

NASA Technical Reports Server (NTRS)

Gao, Yi-Tian; Stecker, Floyd W.; Gleiser, Marcelo; Cline, David B.

1990-01-01

Intrinsic anisotropies in the extragalactic gamma-ray background (EGB), which should be detectable with the forthcoming Gamma Ray Observatory, can be used to examine some of the mechanisms proposed to explain its origin, one of which, the baryon-symmetric big bang (BSBB) model, is investigated here. In this simulation, large domains containing matter and antimatter galaxies produce gamma rays by annihilation at the domain boundaries. This mechanism can produce mountain-chain-shaped angular fluctuations in the EGB flux.

Latest COBE results, large-scale data, and predictions of inflation

NASA Technical Reports Server (NTRS)

Kashlinsky, A.

1992-01-01

One of the predictions of the inflationary scenario of cosmology is that the initial spectrum of primordial density fluctuations (PDFs) must have the Harrison-Zeldovich (HZ) form. Here, in order to test the inflationary scenario, predictions of the microwave background radiation (MBR) anisotropies measured by COBE are computed based on large-scale data for the universe and assuming Omega-1 and the HZ spectrum on large scales. It is found that the minimal scale where the spectrum can first enter the HZ regime is found, constraining the power spectrum of the mass distribution to within the bias factor b. This factor is determined and used to predict parameters of the MBR anisotropy field. For the spectrum of PDFs that reaches the HZ regime immediately after the scale accessible to the APM catalog, the numbers on MBR anisotropies are consistent with the COBE detections and thus the standard inflation can indeed be considered a viable theory for the origin of the large-scale structure in the universe.

Outcomes and Process in Reading Tutoring

ERIC Educational Resources Information Center

Topping, K. J.; Thurston, A.; McGavock, K.; Conlin, N.

2012-01-01

Background: Large-scale randomised controlled trials are relatively rare in education. The present study approximates to, but is not exactly, a randomised controlled trial. It was an attempt to scale up previous small peer tutoring projects, while investing only modestly in continuing professional development for teachers. Purpose: A two-year…

Drug Use Disorder (DUD) Questionnaire: Scale Development and Validation

ERIC Educational Resources Information Center

Scherer, Michael; Furr-Holden, C. Debra; Voas, Robert B.

2013-01-01

Background: Despite the ample interest in the measurement of substance abuse and dependence, obtaining biological samples from participants as a means to validate a scale is considered time and cost intensive and is, subsequently, largely overlooked. Objectives: To report the psychometric properties of the drug use disorder (DUD) questionnaire…

Cosmic microwave background anomalies in an open universe.

PubMed

Liddle, Andrew R; Cortês, Marina

2013-09-13

We argue that the observed large-scale cosmic microwave anomalies, discovered by WMAP and confirmed by the Planck satellite, are most naturally explained in the context of a marginally open universe. Particular focus is placed on the dipole power asymmetry, via an open universe implementation of the large-scale gradient mechanism of Erickcek et al. Open inflation models, which are motivated by the string landscape and which can excite "supercurvature" perturbation modes, can explain the presence of a very-large-scale perturbation that leads to a dipole modulation of the power spectrum measured by a typical observer. We provide a specific implementation of the scenario which appears compatible with all existing constraints.

Large-Angle Anomalies in the CMB

DOE PAGES

Copi, Craig J.; Huterer, Dragan; Schwarz, Dominik J.; ...

2010-01-01

We review the recently found large-scale anomalies in the maps of temperature anisotropies in the cosmic microwave background. These include alignments of the largest modes of CMB anisotropy with each other and with geometry and direction of motion of the solar ssystem, and the unusually low power at these largest scales. We discuss these findings in relation to expectation from standard inflationary cosmology, their statistical significance, the tools to study them, and the various attempts to explain them.

Late time neutrino masses, the LSND experiment, and the cosmic microwave background.

PubMed

Chacko, Z; Hall, Lawrence J; Oliver, Steven J; Perelstein, Maxim

2005-03-25

Models with low-scale breaking of global symmetries in the neutrino sector provide an alternative to the seesaw mechanism for understanding why neutrinos are light. Such models can easily incorporate light sterile neutrinos required by the Liquid Scintillator Neutrino Detector experiment. Furthermore, the constraints on the sterile neutrino properties from nucleosynthesis and large-scale structure can be removed due to the nonconventional cosmological evolution of neutrino masses and densities. We present explicit, fully realistic supersymmetric models, and discuss the characteristic signatures predicted in the angular distributions of the cosmic microwave background.

First Predictions of the Angular Power Spectrum of the Astrophysical Gravitational Wave Background

NASA Astrophysics Data System (ADS)

Cusin, Giulia; Dvorkin, Irina; Pitrou, Cyril; Uzan, Jean-Philippe

2018-06-01

We present the first predictions for the angular power spectrum of the astrophysical gravitational wave background constituted of the radiation emitted by all resolved and unresolved astrophysical sources. Its shape and amplitude depend on both the astrophysical properties on galactic scales and on cosmological properties. We show that the angular power spectrum behaves as Cℓ∝1 /ℓ on large scales and that relative fluctuations of the signal are of order 30% at 100 Hz. We also present the correlations of the astrophysical gravitational wave background with weak lensing and galaxy distribution. These numerical results pave the way to the study of a new observable at the crossroad between general relativity, astrophysics, and cosmology.

REVIEWS OF TOPICAL PROBLEMS: The large-scale structure of the universe

NASA Astrophysics Data System (ADS)

Shandarin, S. F.; Doroshkevich, A. G.; Zel'dovich, Ya B.

1983-01-01

A survey is given of theories for the origin of large-scale structure in the universe: clusters and superclusters of galaxies, and vast black regions practically devoid of galaxies. Special attention is paid to the theory of a neutrino-dominated universe—a cosmology in which electron neutrinos with a rest mass of a few tens of electron volts would contribute the bulk of the mean density. The evolution of small perturbations is discussed, and estimates are made for the temperature anisotropy of the microwave background radiation on various angular scales. The nonlinear stage in the evolution of smooth irrotational perturbations in a lowpressure medium is described in detail. Numerical experiments simulating large-scale structure formation processes are discussed, as well as their interpretation in the context of catastrophe theory.

Unsuppressed primordial standard clocks in warm quasi-single field inflation

NASA Astrophysics Data System (ADS)

Tong, Xi; Wang, Yi; Zhou, Siyi

2018-06-01

We study the non-Gaussianities in quasi-single field inflation with a warm inflation background. The thermal effects at small scales can sufficiently enhance the magnitude of the primordial standard clock signal. This scenario offers us the possibility of probing the UV physics of the very early universe without the exponentially small Boltzmann factor when the mass of the isocurvaton is much heavier than Hubble. The thermal effects at small scales can be studied using the flat space thermal field theory, connected to an effective description using non-Bunch-Davies vacuum at large scales, with large clock signal.

Cluster richness-mass calibration with cosmic microwave background lensing

NASA Astrophysics Data System (ADS)

Geach, James E.; Peacock, John A.

2017-11-01

Identifying galaxy clusters through overdensities of galaxies in photometric surveys is the oldest1,2 and arguably the most economical and mass-sensitive detection method3,4, compared with X-ray5-7 and Sunyaev-Zel'dovich effect8 surveys that detect the hot intracluster medium. However, a perennial problem has been the mapping of optical `richness' measurements onto total cluster mass3,9-12. Emitted at a conformal distance of 14 gigaparsecs, the cosmic microwave background acts as a backlight to all intervening mass in the Universe, and therefore has been gravitationally lensed13-15. Experiments such as the Atacama Cosmology Telescope16, South Pole Telescope17-19 and the Planck20 satellite have now detected gravitational lensing of the cosmic microwave background and produced large-area maps of the foreground deflecting structures. Here we present a calibration of cluster optical richness at the 10% level by measuring the average cosmic microwave background lensing measured by Planck towards the positions of large numbers of optically selected clusters, detecting the deflection of photons by structures of total mass of order 1014 M⊙. Although mainly aimed at the study of larger-scale structures, the Planck estimate of the cosmic microwave background lensing field can be used to recover a nearly unbiased lensing signal for stacked clusters on arcminute scales15,21. This approach offers a clean measure of total cluster masses over most of cosmic history, largely independent of baryon physics.

Die-off rates of Cryptosporidium parvum oocysts in a swine lagoon and in a spray field

USDA-ARS?s Scientific Manuscript database

Background: Because of several large-scale outbreaks of cryptosporidiosis in humans, Cryptosporidium has become a public health concern. Commercial swine operations apply large volumes of effluent from lagoons to spray fields as a waste management practice. This effluent is a source of Cryptosporidi...

Outcomes in a Randomised Controlled Trial of Mathematics Tutoring

ERIC Educational Resources Information Center

Topping, K. J.; Miller, D.; Murray, P.; Henderson, S.; Fortuna, C.; Conlin, N.

2011-01-01

Background: Large-scale randomised controlled trials (RCT) are relatively rare in education. The present study was an attempt to scale up previous small peer tutoring projects, while investing only modestly in continuing professional development for teachers. Purpose: A two-year RCT of peer tutoring in mathematics was undertaken in one local…

On the Cross-Country Comparability of Indicators of Socioeconomic Resources in PISA

ERIC Educational Resources Information Center

Pokropek, Artur; Borgonovi, Francesca; McCormick, Carina

2017-01-01

Large-scale international assessments rely on indicators of the resources that students report having in their homes to capture the financial capital of their families. The scaling methodology currently used to develop the Programme for International Student Assessment (PISA) background indices is designed to maximize within-country comparability…

New probes of Cosmic Microwave Background large-scale anomalies

NASA Astrophysics Data System (ADS)

Aiola, Simone

Fifty years of Cosmic Microwave Background (CMB) data played a crucial role in constraining the parameters of the LambdaCDM model, where Dark Energy, Dark Matter, and Inflation are the three most important pillars not yet understood. Inflation prescribes an isotropic universe on large scales, and it generates spatially-correlated density fluctuations over the whole Hubble volume. CMB temperature fluctuations on scales bigger than a degree in the sky, affected by modes on super-horizon scale at the time of recombination, are a clean snapshot of the universe after inflation. In addition, the accelerated expansion of the universe, driven by Dark Energy, leaves a hardly detectable imprint in the large-scale temperature sky at late times. Such fundamental predictions have been tested with current CMB data and found to be in tension with what we expect from our simple LambdaCDM model. Is this tension just a random fluke or a fundamental issue with the present model? In this thesis, we present a new framework to probe the lack of large-scale correlations in the temperature sky using CMB polarization data. Our analysis shows that if a suppression in the CMB polarization correlations is detected, it will provide compelling evidence for new physics on super-horizon scale. To further analyze the statistical properties of the CMB temperature sky, we constrain the degree of statistical anisotropy of the CMB in the context of the observed large-scale dipole power asymmetry. We find evidence for a scale-dependent dipolar modulation at 2.5sigma. To isolate late-time signals from the primordial ones, we test the anomalously high Integrated Sachs-Wolfe effect signal generated by superstructures in the universe. We find that the detected signal is in tension with the expectations from LambdaCDM at the 2.5sigma level, which is somewhat smaller than what has been previously argued. To conclude, we describe the current status of CMB observations on small scales, highlighting the tensions between Planck, WMAP, and SPT temperature data and how the upcoming data release of the ACTpol experiment will contribute to this matter. We provide a description of the current status of the data-analysis pipeline and discuss its ability to recover large-scale modes.

Eurasian continental background and regionally polluted levels of ozone and CO observed in northeast Asia

NASA Astrophysics Data System (ADS)

Pochanart, Pakpong; Kato, Shungo; Katsuno, Takao; Akimoto, Hajime

The roles of Eurasian/Siberian continental air masses transport and the impact of large-scale East Asian anthropogenic emissions on tropospheric ozone and carbon monoxide levels in northeast Asia were investigated. Seasonal behaviors of O 3 and CO mixing ratios in background continental (BC) air masses and regionally polluted continental (RPC) air masses were identified using trajectory analyses of Eurasian continental air masses and multi-year O 3 and CO data observed at Happo, a mountain site in Japan. RPC air masses show significantly higher O 3 and CO mixing ratios (annual average of 53.9±6.0 and 200±41 ppb, respectively) than BC air masses (44.4±3.6 and 167±17 ppb, respectively). Large scale anthropogenic emissions in East Asia are suggested to contribute about 10 ppb of photochemical O 3 and 32 ppb of CO at Happo. A comparative study of O 3 and CO observed at other sites, i.e., Oki Islands and Mondy in northeast Asia, showed similarities suggesting that O 3 mixing ratios in BC air masses at Happo could be representative for remote northeast Asia. However, CO mixing ratios in BC air masses at Happo are higher than the background level in Siberia. The overestimate is probably related to an increase in the CO baseline gradient between Siberia and the East Asia Pacific rim, and perturbations by sub-grid scale pollution transport and regional-scale boreal forest fires in Siberia when the background continental air masses are transported to Japan.

A gravitational puzzle.

PubMed

Caldwell, Robert R

2011-12-28

The challenge to understand the physical origin of the cosmic acceleration is framed as a problem of gravitation. Specifically, does the relationship between stress-energy and space-time curvature differ on large scales from the predictions of general relativity. In this article, we describe efforts to model and test a generalized relationship between the matter and the metric using cosmological observations. Late-time tracers of large-scale structure, including the cosmic microwave background, weak gravitational lensing, and clustering are shown to provide good tests of the proposed solution. Current data are very close to proving a critical test, leaving only a small window in parameter space in the case that the generalized relationship is scale free above galactic scales.

Cosmic microwave background trispectrum and primordial magnetic field limits.

PubMed

Trivedi, Pranjal; Seshadri, T R; Subramanian, Kandaswamy

2012-06-08

Primordial magnetic fields will generate non-gaussian signals in the cosmic microwave background (CMB) as magnetic stresses and the temperature anisotropy they induce depend quadratically on the magnetic field. We compute a new measure of magnetic non-gaussianity, the CMB trispectrum, on large angular scales, sourced via the Sachs-Wolfe effect. The trispectra induced by magnetic energy density and by magnetic scalar anisotropic stress are found to have typical magnitudes of approximately a few times 10(-29) and 10(-19), respectively. Observational limits on CMB non-gaussianity from WMAP data allow us to conservatively set upper limits of a nG, and plausibly sub-nG, on the present value of the primordial cosmic magnetic field. This represents the tightest limit so far on the strength of primordial magnetic fields, on Mpc scales, and is better than limits from the CMB bispectrum and all modes in the CMB power spectrum. Thus, the CMB trispectrum is a new and more sensitive probe of primordial magnetic fields on large scales.

Does lower Omega allow a resolution of the large-scale structure problem?

NASA Technical Reports Server (NTRS)

Silk, Joseph; Vittorio, Nicola

1987-01-01

The intermediate angular scale anisotropy of the cosmic microwave background, peculiar velocities, density correlations, and mass fluctuations for both neutrino and baryon-dominated universes with Omega less than one are evaluated. The large coherence length associated with a low-Omega, hot dark matter-dominated universe provides substantial density fluctuations on scales up to 100 Mpc: there is a range of acceptable models that are capable of producing large voids and superclusters of galaxies and the clustering of galaxy clusters, with Omega roughly 0.3, without violating any observational constraint. Low-Omega, cold dark matter-dominated cosmologies are also examined. All of these models may be reconciled with the inflationary requirement of a flat universe by introducing a cosmological constant 1-Omega.

Mapping the Heavens: Probing Cosmology with Large Surveys

ScienceCinema

Frieman, Joshua [Fermilab

2017-12-09

This talk will provide an overview of recent and on-going sky surveys, focusing on their implications for cosmology. I will place particular emphasis on the Sloan Digital Sky Survey, the most ambitious mapping of the Universe yet undertaken, showing a virtual fly-through of the survey that reveals the large-scale structure of the galaxy distribution. Recent measurements of this large-scale structure, in combination with observations of the cosmic microwave background, have provided independent evidence for a Universe dominated by dark matter and dark energy as well as insights into how galaxies and larger-scale structures formed. Future planned surveys will build on these foundations to probe the history of the cosmic expansion--and thereby the dark energy--with greater precision.

3-D imaging of large scale buried structure by 1-D inversion of very early time electromagnetic (VETEM) data

USGS Publications Warehouse

Aydmer, A.A.; Chew, W.C.; Cui, T.J.; Wright, D.L.; Smith, D.V.; Abraham, J.D.

2001-01-01

A simple and efficient method for large scale three-dimensional (3-D) subsurface imaging of inhomogeneous background is presented. One-dimensional (1-D) multifrequency distorted Born iterative method (DBIM) is employed in the inversion. Simulation results utilizing synthetic scattering data are given. Calibration of the very early time electromagnetic (VETEM) experimental waveforms is detailed along with major problems encountered in practice and their solutions. This discussion is followed by the results of a large scale application of the method to the experimental data provided by the VETEM system of the U.S. Geological Survey. The method is shown to have a computational complexity that is promising for on-site inversion.

Dynamic field theory and equations of motion in cosmology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kopeikin, Sergei M., E-mail: kopeikins@missouri.edu; Petrov, Alexander N., E-mail: alex.petrov55@gmail.com

2014-11-15

We discuss a field-theoretical approach based on general-relativistic variational principle to derive the covariant field equations and hydrodynamic equations of motion of baryonic matter governed by cosmological perturbations of dark matter and dark energy. The action depends on the gravitational and matter Lagrangian. The gravitational Lagrangian depends on the metric tensor and its first and second derivatives. The matter Lagrangian includes dark matter, dark energy and the ordinary baryonic matter which plays the role of a bare perturbation. The total Lagrangian is expanded in an asymptotic Taylor series around the background cosmological manifold defined as a solution of Einstein’s equationsmore » in the form of the Friedmann–Lemaître–Robertson–Walker (FLRW) metric tensor. The small parameter of the decomposition is the magnitude of the metric tensor perturbation. Each term of the series expansion is gauge-invariant and all of them together form a basis for the successive post-Friedmannian approximations around the background metric. The approximation scheme is covariant and the asymptotic nature of the Lagrangian decomposition does not require the post-Friedmannian perturbations to be small though computationally it works the most effectively when the perturbed metric is close enough to the background FLRW metric. The temporal evolution of the background metric is governed by dark matter and dark energy and we associate the large scale inhomogeneities in these two components as those generated by the primordial cosmological perturbations with an effective matter density contrast δρ/ρ≤1. The small scale inhomogeneities are generated by the condensations of baryonic matter considered as the bare perturbations of the background manifold that admits δρ/ρ≫1. Mathematically, the large scale perturbations are given by the homogeneous solution of the linearized field equations while the small scale perturbations are described by a particular solution of these equations with the bare stress–energy tensor of the baryonic matter. We explicitly work out the covariant field equations of the successive post-Friedmannian approximations of Einstein’s equations in cosmology and derive equations of motion of large and small scale inhomogeneities of dark matter and dark energy. We apply these equations to derive the post-Friedmannian equations of motion of baryonic matter comprising stars, galaxies and their clusters.« less

CMB hemispherical asymmetry from non-linear isocurvature perturbations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Assadullahi, Hooshyar; Wands, David; Firouzjahi, Hassan

2015-04-01

We investigate whether non-adiabatic perturbations from inflation could produce an asymmetric distribution of temperature anisotropies on large angular scales in the cosmic microwave background (CMB). We use a generalised non-linear δ N formalism to calculate the non-Gaussianity of the primordial density and isocurvature perturbations due to the presence of non-adiabatic, but approximately scale-invariant field fluctuations during multi-field inflation. This local-type non-Gaussianity leads to a correlation between very long wavelength inhomogeneities, larger than our observable horizon, and smaller scale fluctuations in the radiation and matter density. Matter isocurvature perturbations contribute primarily to low CMB multipoles and hence can lead to a hemisphericalmore » asymmetry on large angular scales, with negligible asymmetry on smaller scales. In curvaton models, where the matter isocurvature perturbation is partly correlated with the primordial density perturbation, we are unable to obtain a significant asymmetry on large angular scales while respecting current observational constraints on the observed quadrupole. However in the axion model, where the matter isocurvature and primordial density perturbations are uncorrelated, we find it may be possible to obtain a significant asymmetry due to isocurvature modes on large angular scales. Such an isocurvature origin for the hemispherical asymmetry would naturally give rise to a distinctive asymmetry in the CMB polarisation on large scales.« less

Observing the Cosmic Microwave Background Polarization with Variable-delay Polarization Modulators for the Cosmology Large Angular Scale Surveyor

NASA Astrophysics Data System (ADS)

Harrington, Kathleen; CLASS Collaboration

2018-01-01

The search for inflationary primordial gravitational waves and the optical depth to reionization, both through their imprint on the large angular scale correlations in the polarization of the cosmic microwave background (CMB), has created the need for high sensitivity measurements of polarization across large fractions of the sky at millimeter wavelengths. These measurements are subjected to instrumental and atmospheric 1/f noise, which has motivated the development of polarization modulators to facilitate the rejection of these large systematic effects.Variable-delay polarization modulators (VPMs) are used in the Cosmology Large Angular Scale Surveyor (CLASS) telescopes as the first element in the optical chain to rapidly modulate the incoming polarization. VPMs consist of a linearly polarizing wire grid in front of a moveable flat mirror; varying the distance between the grid and the mirror produces a changing phase shift between polarization states parallel and perpendicular to the grid which modulates Stokes U (linear polarization at 45°) and Stokes V (circular polarization). The reflective and scalable nature of the VPM enables its placement as the first optical element in a reflecting telescope. This simultaneously allows a lock-in style polarization measurement and the separation of sky polarization from any instrumental polarization farther along in the optical chain.The Q-Band CLASS VPM was the first VPM to begin observing the CMB full time in 2016. I will be presenting its design and characterization as well as demonstrating how modulating polarization significantly rejects atmospheric and instrumental long time scale noise.

The Timing of Teacher Hires and Teacher Qualifications: Is There an Association?

ERIC Educational Resources Information Center

Engel, Mimi

2012-01-01

Background: Case studies suggest that late hiring timelines are common in large urban school districts and result in the loss of qualified teachers to surrounding suburbs. To date, however, there has been no large-scale quantitative investigation of the relationship between the timing of teacher hires and teacher qualifications. Purpose: This…

Large Aperture Camera for the Simon's Observatory

NASA Astrophysics Data System (ADS)

Dicker, Simon; Simons Observatory Collaboration

2018-01-01

The Simon's observatory will consist of one large 6m telescope and three or more smaller telescopes working together with a goal of measuring the polarization in the Cosmic Microwave Background on angular scales as small as 1' to larger than 1 degree and at a sensitivity far greater than has ever been reached before. To reach these sensitivities, needed for our science goals, we require over 90000 background limited TES detectors on the large telescope - hence a very large field-of-view. The telescope design we have selected is a copy of the CCAT-prime telescope, a Crossed Dragone with extra aspheric terms to increase the diffraction limited field-of-view. At the secondary focus will be a 2.5m diameter cryostat containing re-imaging silicon optics which can correct remaining aberrations (mostly astigmatism) at the edge of the field of view and allow this part of the focal plane to be used at higher frequencies. This poster will contain an outline of our optical designs and take a brief look at how they could be scaled to a larger telescope.

Spatial Fluctuations in the Diffuse Cosmic X-Ray Background. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Shafer, R. A.

1983-01-01

The bright, essentially isotropic, X-ray sky flux above 2 keV yields information on the universe at large distances. However, a definitive understanding of the origin of the flux is lacking. Some fraction of the total flux is contributed by active galactic nuclei and clusters of galaxies, but less than one percent of the total is contributed by the or approximately 3 keV band resolved sources, which is the band where the sky flux is directly observed. Parametric models of AGN (quasar) luminosity function evolution are examined. Most constraints are by the total sky flux. The acceptability of particular models hinges on assumptions currently not directly testable. The comparison with the Einstein Observatory 1 to keV low flux source counts is hampered by spectral uncertainties. A tentative measurement of a large scale dipole anisotropy is consistent with the velocity and direction derived from the dipole in the microwave background. The impact of the X-ray anisotropy limits for other scales on studies of large-scale structure in the universe is sketched. Models of the origins of the X-ray sky flux are reviewed, and future observational programs outlined.

Power suppression at large scales in string inflation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cicoli, Michele; Downes, Sean; Dutta, Bhaskar, E-mail: mcicoli@ictp.it, E-mail: sddownes@physics.tamu.edu, E-mail: dutta@physics.tamu.edu

2013-12-01

We study a possible origin of the anomalous suppression of the power spectrum at large angular scales in the cosmic microwave background within the framework of explicit string inflationary models where inflation is driven by a closed string modulus parameterizing the size of the extra dimensions. In this class of models the apparent power loss at large scales is caused by the background dynamics which involves a sharp transition from a fast-roll power law phase to a period of Starobinsky-like slow-roll inflation. An interesting feature of this class of string inflationary models is that the number of e-foldings of inflationmore » is inversely proportional to the string coupling to a positive power. Therefore once the string coupling is tuned to small values in order to trust string perturbation theory, enough e-foldings of inflation are automatically obtained without the need of extra tuning. Moreover, in the less tuned cases the sharp transition responsible for the power loss takes place just before the last 50-60 e-foldings of inflation. We illustrate these general claims in the case of Fibre Inflation where we study the strength of this transition in terms of the attractor dynamics, finding that it induces a pivot from a blue to a redshifted power spectrum which can explain the apparent large scale power loss. We compute the effects of this pivot for example cases and demonstrate how magnitude and duration of this effect depend on model parameters.« less

Power suppression at large scales in string inflation

NASA Astrophysics Data System (ADS)

Cicoli, Michele; Downes, Sean; Dutta, Bhaskar

2013-12-01

We study a possible origin of the anomalous suppression of the power spectrum at large angular scales in the cosmic microwave background within the framework of explicit string inflationary models where inflation is driven by a closed string modulus parameterizing the size of the extra dimensions. In this class of models the apparent power loss at large scales is caused by the background dynamics which involves a sharp transition from a fast-roll power law phase to a period of Starobinsky-like slow-roll inflation. An interesting feature of this class of string inflationary models is that the number of e-foldings of inflation is inversely proportional to the string coupling to a positive power. Therefore once the string coupling is tuned to small values in order to trust string perturbation theory, enough e-foldings of inflation are automatically obtained without the need of extra tuning. Moreover, in the less tuned cases the sharp transition responsible for the power loss takes place just before the last 50-60 e-foldings of inflation. We illustrate these general claims in the case of Fibre Inflation where we study the strength of this transition in terms of the attractor dynamics, finding that it induces a pivot from a blue to a redshifted power spectrum which can explain the apparent large scale power loss. We compute the effects of this pivot for example cases and demonstrate how magnitude and duration of this effect depend on model parameters.

Natural Covariant Planck Scale Cutoffs and the Cosmic Microwave Background Spectrum.

PubMed

Chatwin-Davies, Aidan; Kempf, Achim; Martin, Robert T W

2017-07-21

We calculate the impact of quantum gravity-motivated ultraviolet cutoffs on inflationary predictions for the cosmic microwave background spectrum. We model the ultraviolet cutoffs fully covariantly to avoid possible artifacts of covariance breaking. Imposing these covariant cutoffs results in the production of small, characteristically k-dependent oscillations in the spectrum. The size of the effect scales linearly with the ratio of the Planck to Hubble lengths during inflation. Consequently, the relative size of the effect could be as large as one part in 10^{5}; i.e., eventual observability may not be ruled out.

Stochastic inflation lattice simulations - Ultra-large scale structure of the universe

NASA Technical Reports Server (NTRS)

Salopek, D. S.

1991-01-01

Non-Gaussian fluctuations for structure formation may arise in inflation from the nonlinear interaction of long wavelength gravitational and scalar fields. Long wavelength fields have spatial gradients, a (exp -1), small compared to the Hubble radius, and they are described in terms of classical random fields that are fed by short wavelength quantum noise. Lattice Langevin calculations are given for a toy model with a scalar field interacting with an exponential potential where one can obtain exact analytic solutions of the Fokker-Planck equation. For single scalar field models that are consistent with current microwave background fluctuations, the fluctuations are Gaussian. However, for scales much larger than our observable Universe, one expects large metric fluctuations that are non-Gaussian. This example illuminates non-Gaussian models involving multiple scalar fields which are consistent with current microwave background limits.

Bounds on isocurvature perturbations from cosmic microwave background and large scale structure data.

PubMed

Crotty, Patrick; García-Bellido, Juan; Lesgourgues, Julien; Riazuelo, Alain

2003-10-24

We obtain very stringent bounds on the possible cold dark matter, baryon, and neutrino isocurvature contributions to the primordial fluctuations in the Universe, using recent cosmic microwave background and large scale structure data. Neglecting the possible effects of spatial curvature, tensor perturbations, and reionization, we perform a Bayesian likelihood analysis with nine free parameters, and find that the amplitude of the isocurvature component cannot be larger than about 31% for the cold dark matter mode, 91% for the baryon mode, 76% for the neutrino density mode, and 60% for the neutrino velocity mode, at 2sigma, for uncorrelated models. For correlated adiabatic and isocurvature components, the fraction could be slightly larger. However, the cross-correlation coefficient is strongly constrained, and maximally correlated/anticorrelated models are disfavored. This puts strong bounds on the curvaton model.

Spatial Temporal Mathematics at Scale: An Innovative and Fully Developed Paradigm to Boost Math Achievement among All Learners

ERIC Educational Resources Information Center

Rutherford, Teomara; Kibrick, Melissa; Burchinal, Margaret; Richland, Lindsey; Conley, AnneMarie; Osborne, Keara; Schneider, Stephanie; Duran, Lauren; Coulson, Andrew; Antenore, Fran; Daniels, Abby; Martinez, Michael E.

2010-01-01

This paper describes the background, methodology, preliminary findings, and anticipated future directions of a large-scale multi-year randomized field experiment addressing the efficacy of ST Math [Spatial-Temporal Math], a fully-developed math curriculum that uses interactive animated software. ST Math's unique approach minimizes the use of…

Testing the Predictors of Boredom at School: Development and Validation of the Precursors to Boredom Scales

ERIC Educational Resources Information Center

Daschmann, Elena C.; Goetz, Thomas; Stupnisky, Robert H.

2011-01-01

Background: Boredom has been found to be an important emotion for students' learning processes and achievement outcomes; however, the precursors of this emotion remain largely unexplored. Aim: In the current study, scales assessing the precursors to boredom in academic achievement settings were developed and tested. Sample: Participants were 1,380…

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eisenstein, Daniel J.

I review the use of cosmological large-scale structure to measure properties of neutrinos and other relic populations of light relativistic particles. With experiments to measure the anisotropies of the cosmic microwave anisotropies and the clustering of matter at low redshift, we now have securely measured a relativistic background with density appropriate to the cosmic neutrino background. Our limits on the mass of the neutrino continue to shrink. Experiments coming in the next decade will greatly improve the available precision on searches for the energy density of novel relativistic backgrounds and the mass of neutrinos.

ΛGR Centennial: Cosmic Web in Dark Energy Background

NASA Astrophysics Data System (ADS)

Chernin, A. D.

The basic building blocks of the Cosmic Web are groups and clusters of galaxies, super-clusters (pancakes) and filaments embedded in the universal dark energy background. The background produces antigravity, and the antigravity effect is strong in groups, clusters and superclusters. Antigravity is very weak in filaments where matter (dark matter and baryons) produces gravity dominating in the filament internal dynamics. Gravity-antigravity interplay on the large scales is a grandiose phenomenon predicted by ΛGR theory and seen in modern observations of the Cosmic Web.

Large-Angular-Scale Anisotropy in the Cosmic Background Radiation

DOE R&D Accomplishments Database

Gorenstein, M. V.; Smoot, G. F.

1980-05-01

We report the results of an extended series of airborne measurements of large-angular-scale anisotropy in the 3 K cosmic background radiation. Observations were carried out with a dual-antenna microwave radiometer operating at 33 GHz (.089 cm wavelength) flown on board a U-2 aircraft to 20 km altitude. In eleven flights, between December 1976 and May 1978, the radiometer measured differential intensity between pairs of directions distributed over most of the northern hemisphere with an rms sensitivity of 47 mK Hz{sup 1?}. The measurements how clear evidence of anisotropy that is readily interpreted as due to the solar motion relative to the sources of the radiation. The anisotropy is well fit by a first order spherical harmonic of amplitude 360{+ or -}50km sec{sup -1} toward the direction 11.2{+ or -}0.5 hours of right ascension and 19 {+ or -}8 degrees declination. A simultaneous fit to a combined hypotheses of dipole and quadrupole angular distributions places a 1 mK limit on the amplitude of most components of quadrupole anisotropy with 90% confidence. Additional analysis places a 0.5 mK limit on uncorrelated fluctuations (sky-roughness) in the 3 K background on an angular scale of the antenna beam width, about 7 degrees.

Individual, Social, and Family Factors Associated with High School Dropout among Low-SES Youth: Differential Effects as a Function of Immigrant Status

ERIC Educational Resources Information Center

Archambault, Isabelle; Janosz, Michel; Dupéré, Véronique; Brault, Marie-Christine; Andrew, Marie Mc

2017-01-01

Background: In most Western countries, the individual, social, and family characteristics associated with students' dropout in the general population are well documented. Yet, there is a lack of large-scale studies to establish whether these characteristics have the same influence for students with an immigrant background. Aims: The first aim of…

Probing large-scale magnetism with the cosmic microwave background

NASA Astrophysics Data System (ADS)

Giovannini, Massimo

2018-04-01

Prior to photon decoupling magnetic random fields of comoving intensity in the nano-Gauss range distort the temperature and the polarization anisotropies of the microwave background, potentially induce a peculiar B-mode power spectrum and may even generate a frequency-dependent circularly polarized V-mode. We critically analyze the theoretical foundations and the recent achievements of an interesting trialogue involving plasma physics, general relativity and astrophysics.

Magnetic Fields Recorded by Chondrules Formed in Nebular Shocks

NASA Astrophysics Data System (ADS)

Mai, Chuhong; Desch, Steven J.; Boley, Aaron C.; Weiss, Benjamin P.

2018-04-01

Recent laboratory efforts have constrained the remanent magnetizations of chondrules and the magnetic field strengths to which the chondrules were exposed as they cooled below their Curie points. An outstanding question is whether the inferred paleofields represent the background magnetic field of the solar nebula or were unique to the chondrule-forming environment. We investigate the amplification of the magnetic field above background values for two proposed chondrule formation mechanisms, large-scale nebular shocks and planetary bow shocks. Behind large-scale shocks, the magnetic field parallel to the shock front is amplified by factors of ∼10–30, regardless of the magnetic diffusivity. Therefore, chondrules melted in these shocks probably recorded an amplified magnetic field. Behind planetary bow shocks, the field amplification is sensitive to the magnetic diffusivity. We compute the gas properties behind a bow shock around a 3000 km radius planetary embryo, with and without atmospheres, using hydrodynamics models. We calculate the ionization state of the hot, shocked gas, including thermionic emission from dust, thermal ionization of gas-phase potassium atoms, and the magnetic diffusivity due to Ohmic dissipation and ambipolar diffusion. We find that the diffusivity is sufficiently large that magnetic fields have already relaxed to background values in the shock downstream where chondrules acquire magnetizations, and that these locations are sufficiently far from the planetary embryos that chondrules should not have recorded a significant putative dynamo field generated on these bodies. We conclude that, if melted in planetary bow shocks, chondrules probably recorded the background nebular field.

Gravitational waves at interferometer scales and primordial black holes in axion inflation

DOE Office of Scientific and Technical Information (OSTI.GOV)

García-Bellido, Juan; Peloso, Marco; Unal, Caner, E-mail: juan.garciabellido@uam.es, E-mail: peloso@physics.umn.edu, E-mail: unal@physics.umn.edu

We study the prospects of detection at terrestrial and space interferometers, as well as at pulsar timing array experiments, of a stochastic gravitational wave background which can be produced in models of axion inflation. This potential signal, and the development of these experiments, open a new window on inflation on scales much smaller than those currently probed with Cosmic Microwave Background and Large Scale Structure measurements. The sourced signal generated in axion inflation is an ideal candidate for such searches, since it naturally grows at small scales, and it has specific properties (chirality and non-gaussianity) that can distinguish it frommore » an astrophysical background. We study under which conditions such a signal can be produced at an observable level, without the simultaneous overproduction of scalar perturbations in excess of what is allowed by the primordial black hole limits. We also explore the possibility that scalar perturbations generated in a modified version of this model may provide a distribution of primordial black holes compatible with the current bounds, that can act as a seeds of the present black holes in the universe.« less

Is There Any Real Observational Contradictoty To The Lcdm Model?

NASA Astrophysics Data System (ADS)

Ma, Yin-Zhe

2011-01-01

In this talk, I am going to question the two apparent observational contradictories to LCDM cosmology---- the lack of large angle correlations in the cosmic microwave background, and the very large bulk flow of galaxy peculiar velocities. On the super-horizon scale, "Copi etal. (2009)” have been arguing that the lack of large angular correlations of the CMB temperature field provides strong evidence against the standard, statistically isotropic, LCDM cosmology. I am going to argue that the "ad-hoc” discrepancy is due to the sub-optimal estimator of the low-l multipoles, and a posteriori statistics, which exaggerates the statistical significance. On Galactic scales, "Watkins et al. (2008)” shows that the very large bulk flow prefers a very large density fluctuation, which seems to contradict to the LCDM model. I am going to show that these results are due to their underestimation of the small scale velocity dispersion, and an arbitrary way of combining catalogues. With the appropriate way of combining catalogue data, as well as the treating the small scale velocity dispersion as a free parameter, the peculiar velocity field provides unconvincing evidence against LCDM cosmology.

Multi-scale structures of turbulent magnetic reconnection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nakamura, T. K. M., E-mail: takuma.nakamura@oeaw.ac.at; Nakamura, R.; Narita, Y.

2016-05-15

We have analyzed data from a series of 3D fully kinetic simulations of turbulent magnetic reconnection with a guide field. A new concept of the guide filed reconnection process has recently been proposed, in which the secondary tearing instability and the resulting formation of oblique, small scale flux ropes largely disturb the structure of the primary reconnection layer and lead to 3D turbulent features [W. Daughton et al., Nat. Phys. 7, 539 (2011)]. In this paper, we further investigate the multi-scale physics in this turbulent, guide field reconnection process by introducing a wave number band-pass filter (k-BPF) technique in whichmore » modes for the small scale (less than ion scale) fluctuations and the background large scale (more than ion scale) variations are separately reconstructed from the wave number domain to the spatial domain in the inverse Fourier transform process. Combining with the Fourier based analyses in the wave number domain, we successfully identify spatial and temporal development of the multi-scale structures in the turbulent reconnection process. When considering a strong guide field, the small scale tearing mode and the resulting flux ropes develop over a specific range of oblique angles mainly along the edge of the primary ion scale flux ropes and reconnection separatrix. The rapid merging of these small scale modes leads to a smooth energy spectrum connecting ion and electron scales. When the guide field is sufficiently weak, the background current sheet is strongly kinked and oblique angles for the small scale modes are widely scattered at the kinked regions. Similar approaches handling both the wave number and spatial domains will be applicable to the data from multipoint, high-resolution spacecraft observations such as the NASA magnetospheric multiscale (MMS) mission.« less

Multi-scale structures of turbulent magnetic reconnection

NASA Astrophysics Data System (ADS)

Nakamura, T. K. M.; Nakamura, R.; Narita, Y.; Baumjohann, W.; Daughton, W.

2016-05-01

We have analyzed data from a series of 3D fully kinetic simulations of turbulent magnetic reconnection with a guide field. A new concept of the guide filed reconnection process has recently been proposed, in which the secondary tearing instability and the resulting formation of oblique, small scale flux ropes largely disturb the structure of the primary reconnection layer and lead to 3D turbulent features [W. Daughton et al., Nat. Phys. 7, 539 (2011)]. In this paper, we further investigate the multi-scale physics in this turbulent, guide field reconnection process by introducing a wave number band-pass filter (k-BPF) technique in which modes for the small scale (less than ion scale) fluctuations and the background large scale (more than ion scale) variations are separately reconstructed from the wave number domain to the spatial domain in the inverse Fourier transform process. Combining with the Fourier based analyses in the wave number domain, we successfully identify spatial and temporal development of the multi-scale structures in the turbulent reconnection process. When considering a strong guide field, the small scale tearing mode and the resulting flux ropes develop over a specific range of oblique angles mainly along the edge of the primary ion scale flux ropes and reconnection separatrix. The rapid merging of these small scale modes leads to a smooth energy spectrum connecting ion and electron scales. When the guide field is sufficiently weak, the background current sheet is strongly kinked and oblique angles for the small scale modes are widely scattered at the kinked regions. Similar approaches handling both the wave number and spatial domains will be applicable to the data from multipoint, high-resolution spacecraft observations such as the NASA magnetospheric multiscale (MMS) mission.

Dark matter, long-range forces, and large-scale structure

NASA Technical Reports Server (NTRS)

Gradwohl, Ben-Ami; Frieman, Joshua A.

1992-01-01

If the dark matter in galaxies and clusters is nonbaryonic, it can interact with additional long-range fields that are invisible to experimental tests of the equivalence principle. We discuss the astrophysical and cosmological implications of a long-range force coupled only to the dark matter and find rather tight constraints on its strength. If the force is repulsive (attractive), the masses of galaxy groups and clusters (and the mean density of the universe inferred from them) have been systematically underestimated (overestimated). We explore the consequent effects on the two-point correlation function, large-scale velocity flows, and microwave background anisotropies, for models with initial scale-invariant adiabatic perturbations and cold dark matter.

COSMIC INFRARED BACKGROUND FLUCTUATIONS AND ZODIACAL LIGHT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arendt, Richard G.; Kashlinsky, A.; Moseley, S. H.

We performed a specific observational test to measure the effect that the zodiacal light can have on measurements of the spatial fluctuations of the near-IR background. Previous estimates of possible fluctuations caused by zodiacal light have often been extrapolated from observations of the thermal emission at longer wavelengths and low angular resolution or from IRAC observations of high-latitude fields where zodiacal light is faint and not strongly varying with time. The new observations analyzed here target the COSMOS field at low ecliptic latitude where the zodiacal light intensity varies by factors of ∼2 over the range of solar elongations atmore » which the field can be observed. We find that the white-noise component of the spatial power spectrum of the background is correlated with the modeled zodiacal light intensity. Roughly half of the measured white noise is correlated with the zodiacal light, but a more detailed interpretation of the white noise is hampered by systematic uncertainties that are evident in the zodiacal light model. At large angular scales (≳100″) where excess power above the white noise is observed, we find no correlation of the power with the modeled intensity of the zodiacal light. This test clearly indicates that the large-scale power in the infrared background is not being caused by the zodiacal light.« less

Cosmic Infrared Background Fluctuations and Zodiacal Light

NASA Astrophysics Data System (ADS)

Arendt, Richard G.; Kashlinsky, A.; Moseley, S. H.; Mather, J.

2016-06-01

We performed a specific observational test to measure the effect that the zodiacal light can have on measurements of the spatial fluctuations of the near-IR background. Previous estimates of possible fluctuations caused by zodiacal light have often been extrapolated from observations of the thermal emission at longer wavelengths and low angular resolution or from IRAC observations of high-latitude fields where zodiacal light is faint and not strongly varying with time. The new observations analyzed here target the COSMOS field at low ecliptic latitude where the zodiacal light intensity varies by factors of ˜2 over the range of solar elongations at which the field can be observed. We find that the white-noise component of the spatial power spectrum of the background is correlated with the modeled zodiacal light intensity. Roughly half of the measured white noise is correlated with the zodiacal light, but a more detailed interpretation of the white noise is hampered by systematic uncertainties that are evident in the zodiacal light model. At large angular scales (≳100″) where excess power above the white noise is observed, we find no correlation of the power with the modeled intensity of the zodiacal light. This test clearly indicates that the large-scale power in the infrared background is not being caused by the zodiacal light.

The microphysics and macrophysics of cosmic rays

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zweibel, Ellen G.

2013-05-15

This review paper commemorates a century of cosmic ray research, with emphasis on the plasma physics aspects. Cosmic rays comprise only ∼10{sup −9} of interstellar particles by number, but collectively their energy density is about equal to that of the thermal particles. They are confined by the Galactic magnetic field and well scattered by small scale magnetic fluctuations, which couple them to the local rest frame of the thermal fluid. Scattering isotropizes the cosmic rays and allows them to exchange momentum and energy with the background medium. I will review a theory for how the fluctuations which scatter the cosmicmore » rays can be generated by the cosmic rays themselves through a microinstability excited by their streaming. A quasilinear treatment of the cosmic ray–wave interaction then leads to a fluid model of cosmic rays with both advection and diffusion by the background medium and momentum and energy deposition by the cosmic rays. This fluid model admits cosmic ray modified shocks, large scale cosmic ray driven instabilities, cosmic ray heating of the thermal gas, and cosmic ray driven galactic winds. If the fluctuations were extrinsic turbulence driven by some other mechanism, the cosmic ray background coupling would be entirely different. Which picture holds depends largely on the nature of turbulence in the background medium.« less

Variations of trends of indicators describing complex systems: Change of scaling precursory to extreme events

NASA Astrophysics Data System (ADS)

Keilis-Borok, V. I.; Soloviev, A. A.

2010-09-01

Socioeconomic and natural complex systems persistently generate extreme events also known as disasters, crises, or critical transitions. Here we analyze patterns of background activity preceding extreme events in four complex systems: economic recessions, surges in homicides in a megacity, magnetic storms, and strong earthquakes. We use as a starting point the indicators describing the system's behavior and identify changes in an indicator's trend. Those changes constitute our background events (BEs). We demonstrate a premonitory pattern common to all four systems considered: relatively large magnitude BEs become more frequent before extreme event. A premonitory change of scaling has been found in various models and observations. Here we demonstrate this change in scaling of uniformly defined BEs in four real complex systems, their enormous differences notwithstanding.

Exploring Anxiety Symptoms in a Large-Scale Twin Study of Children with Autism Spectrum Disorders, Their Co-Twins and Controls

ERIC Educational Resources Information Center

Hallett, Victoria; Ronald, Angelica; Colvert, Emma; Ames, Catherine; Woodhouse, Emma; Lietz, Stephanie; Garnett, Tracy; Gillan, Nicola; Rijsdijk, Fruhling; Scahill, Lawrence; Bolton, Patrick; Happé, Francesca

2013-01-01

Background: Although many children with autism spectrum disorders (ASDs) experience difficulties with anxiety, the manifestation of these difficulties remains unresolved. The current study assessed anxiety in a large population-based twin sample, aged 10-15 years. Phenotypic analyses were used to explore anxiety symptoms in children with ASDs,…

Identification and measurement of shrub type vegetation on large scale aerial photography

NASA Technical Reports Server (NTRS)

Driscoll, R. S.

1970-01-01

Important range-shrub species were identified at acceptable levels of accuracy on large-scale 70 mm color and color infrared aerial photographs. Identification of individual shrubs was significantly higher, however, on color infrared. Photoscales smaller than 1:2400 had limited value except for mature individuals of relatively tall species, and then only if crown margins did not overlap and sharp contrast was evident between the species and background. Larger scale photos were required for low-growing species in dense stands. The crown cover for individual species was estimated from the aerial photos either with a measuring magnifier or a projected-scale micrometer. These crown cover measurements provide techniques for earth-resource analyses when used in conjunction with space and high-altitude remotely procured photos.

Wind Power Innovation Enables Shift to Utility-Scale - Continuum Magazine

Science.gov Websites

the 1930s, a farmer in South Dakota built a small wind turbine on his farm, generating enough enough electricity to power thousands of homes. Aerial photo of large wind turbine with mountains in the background. Aerial view of the Siemens utility-scale wind turbine at the National Wind Technology Center

Possible evidence for the existence of antimatter on a cosmological scale in the universe.

NASA Technical Reports Server (NTRS)

Stecker, F. W.; Morgan, D. L., Jr.; Bredekamp, J.

1971-01-01

Initial results of a detailed calculation of the cosmological gamma-ray spectrum from matter-antimatter annihilation in the universe. The similarity between the calculated spectrum and the present observations of the gamma-ray background spectrum above 1 MeV suggests that such observations may be evidence of the existence of antimatter on a large scale in the universe.

Improvement of individual camouflage through background choice in ground-nesting birds.

PubMed

Stevens, Martin; Troscianko, Jolyon; Wilson-Aggarwal, Jared K; Spottiswoode, Claire N

2017-09-01

Animal camouflage is a longstanding example of adaptation. Much research has tested how camouflage prevents detection and recognition, largely focusing on changes to an animal's own appearance over evolution. However, animals could also substantially alter their camouflage by behaviourally choosing appropriate substrates. Recent studies suggest that individuals from several animal taxa could select backgrounds or positions to improve concealment. Here, we test whether individual wild animals choose backgrounds in complex environments, and whether this improves camouflage against predator vision. We studied nest site selection by nine species of ground-nesting birds (nightjars, plovers and coursers) in Zambia, and used image analysis and vision modeling to quantify egg and plumage camouflage to predator vision. Individual birds chose backgrounds that enhanced their camouflage, being better matched to their chosen backgrounds than to other potential backgrounds with respect to multiple aspects of camouflage. This occurred at all three spatial scales tested (a few cm and five meters from the nest, and compared to other sites chosen by conspecifics), and was the case for the eggs of all bird groups studied, and for adult nightjar plumage. Thus, individual wild animals improve their camouflage through active background choice, with choices highly refined across multiple spatial scales.

Improvement of individual camouflage through background choice in ground-nesting birds

PubMed Central

Stevens, Martin; Troscianko, Jolyon; Wilson-Aggarwal, Jared K.; Spottiswoode, Claire N.

2017-01-01

Animal camouflage is a longstanding example of adaptation. Much research has tested how camouflage prevents detection and recognition, largely focusing on changes to an animal's own appearance over evolution. However, animals could also substantially alter their camouflage by behaviourally choosing appropriate substrates. Recent studies suggest that individuals from several animal taxa could select backgrounds or positions to improve concealment. Here, we test whether individual wild animals choose backgrounds in complex environments, and whether this improves camouflage against predator vision. We studied nest site selection by nine species of ground-nesting birds (nightjars, plovers and coursers) in Zambia, and used image analysis and vision modeling to quantify egg and plumage camouflage to predator vision. Individual birds chose backgrounds that enhanced their camouflage, being better matched to their chosen backgrounds than to other potential backgrounds with respect to multiple aspects of camouflage. This occurred at all three spatial scales tested (a few cm and five meters from the nest, and compared to other sites chosen by conspecifics), and was the case for the eggs of all bird groups studied, and for adult nightjar plumage. Thus, individual wild animals improve their camouflage through active background choice, with choices highly refined across multiple spatial scales. PMID:28890937

Gravitational waves during inflation from a 5D large-scale repulsive gravity model

NASA Astrophysics Data System (ADS)

Reyes, Luz M.; Moreno, Claudia; Madriz Aguilar, José Edgar; Bellini, Mauricio

2012-10-01

We investigate, in the transverse traceless (TT) gauge, the generation of the relic background of gravitational waves, generated during the early inflationary stage, on the framework of a large-scale repulsive gravity model. We calculate the spectrum of the tensor metric fluctuations of an effective 4D Schwarzschild-de Sitter metric on cosmological scales. This metric is obtained after implementing a planar coordinate transformation on a 5D Ricci-flat metric solution, in the context of a non-compact Kaluza-Klein theory of gravity. We found that the spectrum is nearly scale invariant under certain conditions. One interesting aspect of this model is that it is possible to derive the dynamical field equations for the tensor metric fluctuations, valid not just at cosmological scales, but also at astrophysical scales, from the same theoretical model. The astrophysical and cosmological scales are determined by the gravity-antigravity radius, which is a natural length scale of the model, that indicates when gravity becomes repulsive in nature.

Proposed square spiral microfabrication architecture for large three-dimensional photonic band gap crystals.

PubMed

Toader, O; John, S

2001-05-11

We present a blueprint for a three-dimensional photonic band gap (PBG) material that is amenable to large-scale microfabrication on the optical scale using glancing angle deposition methods. The proposed chiral crystal consists of square spiral posts on a tetragonal lattice. In the case of silicon posts in air (direct structure), the full PBG can be as large as 15% of the gap center frequency, whereas for air posts in a silicon background (inverted structure) the maximum PBG is 24% of the center frequency. This PBG occurs between the fourth and fifth bands of the photon dispersion relation and is very robust to variations (disorder) in the geometrical parameters of the crystal.

Generating scale-invariant perturbations from rapidly-evolving equation of state

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khoury, Justin; Steinhardt, Paul J.

2011-06-15

Recently, we introduced an ekpyrotic model based on a single, canonical scalar field that generates nearly scale-invariant curvature fluctuations through a purely ''adiabatic mechanism'' in which the background evolution is a dynamical attractor. Despite the starkly different physical mechanism for generating fluctuations, the two-point function is identical to inflation. In this paper, we further explore this concept, focusing in particular on issues of non-Gaussianity and quantum corrections. We find that the degeneracy with inflation is broken at three-point level: for the simplest case of an exponential potential, the three-point amplitude is strongly scale dependent, resulting in a breakdown of perturbationmore » theory on small scales. However, we show that the perturbative breakdown can be circumvented--and all issues raised in Linde et al. (arXiv:0912.0944) can be addressed--by altering the potential such that power is suppressed on small scales. The resulting range of nearly scale-invariant, Gaussian modes can be as much as 12 e-folds, enough to span the scales probed by microwave background and large-scale structure observations. On smaller scales, the spectrum is not scale invariant but is observationally acceptable.« less

Experiments with a New, Unique Large-Scale Rig Investigating the Effects of Background System Rotation on Vortex Rings in Water

NASA Astrophysics Data System (ADS)

Brend, Mark A.; Verzicco, Roberto

2005-11-01

We introduce our unique, new large-scale experimental facility [1] designed for our long-term research program investigating the effects of background system rotation on the stability and the dynamics of vortex rings. The new rig constitutes a large water-filled tank positioned on a rotating turntable and its overall height and diameter are 5.7m and 1.4 m, respectively. First experimental and computational results of our program are summarized. We will show various videos of flow visualizations that illustrate some major, qualitative differences between rings propagating in rotating and non-rotating flows. Some of the investigated characteristics of the vortex rings include their translation velocity, the velocity field inside and surrounding the rings, and, in particular, their stability. We will briefly outline experiments employing the relatively new Ultrasonic-Velocity-Profiler technique (UVP). This technique appears to be particularly suited for some of our measurements and it was, as far as we are aware, not previously used in the context of vortex-ring studies. [1] http://www.eng.warwick.ac.uk/staff/pjt/turntabpics/voriskt.html

Mapping the integrated Sachs-Wolfe effect

NASA Astrophysics Data System (ADS)

Manzotti, A.; Dodelson, S.

2014-12-01

On large scales, the anisotropies in the cosmic microwave background (CMB) reflect not only the primordial density field but also the energy gain when photons traverse decaying gravitational potentials of large scale structure, what is called the integrated Sachs-Wolfe (ISW) effect. Decomposing the anisotropy signal into a primordial piece and an ISW component, the main secondary effect on large scales, is more urgent than ever as cosmologists strive to understand the Universe on those scales. We present a likelihood technique for extracting the ISW signal combining measurements of the CMB, the distribution of galaxies, and maps of gravitational lensing. We test this technique with simulated data showing that we can successfully reconstruct the ISW map using all the data sets together. Then we present the ISW map obtained from a combination of real data: the NRAO VLA sky survey (NVSS) galaxy survey, temperature anisotropies, and lensing maps made by the Planck satellite. This map shows that, with the data sets used and assuming linear physics, there is no evidence, from the reconstructed ISW signal in the Cold Spot region, for an entirely ISW origin of this large scale anomaly in the CMB. However a large scale structure origin from low redshift voids outside the NVSS redshift range is still possible. Finally we show that future surveys, thanks to a better large scale lensing reconstruction will be able to improve the reconstruction signal to noise which is now mainly coming from galaxy surveys.

Low Frequency Measurement of the Spectrum of the Cosmic Background Radiation

DOE R&D Accomplishments Database

Smoot, G. F.; De Amici, G.; Friedman, S. D.; Witebsky, C.; Mandolesi, N.; Partridge, R. B.; Sironi, G.; Danese, L.; De Zotti, G.

1983-06-01

We have made measurements of the cosmic background radiation spectrum at 5 wavelengths (0.33, 0.9, 3, 6.3, and 12 cm) using radiometers with wavelength-scaled corrugated horn antennas having very low sidelobes. A single large-mouth (0.7 m diameter) liquid-helium-cooled absolute reference load was used for all five radiometers. The results of the observations are consistent with previous measurements and represent a significant improvement in accuracy.

Background Lamb waves in the Earth's atmosphere

NASA Astrophysics Data System (ADS)

Nishida, K.; Kobayashi, N.; Fukao, Y.

2013-12-01

Lamb waves of the Earth's atmosphere in the millihertz band have been considered as transient phenomena excited only by large events [e.g. the major volcanic eruption of Krakatoa in 1833, the impact of Siberian meteorite in 1908, the testing of large nuclear tests and the huge earthquakes, Garrett1969]. In a case of the solid Earth, observation of background free oscillations in the millihertz band-now known as Earth's background free oscillations or seismic hum, has been firmly established. Above 5 mHz, their dominant excitation sources are oceanic infragravity waves. At 3.7 and 4.4 mHz an elasto-acoustic resonance between the solid Earth and the atmosphere was observed [Nishida et al., 2000]. These seismic observations show that the contribution of atmospheric disturbances to the seismic hum is dominant below 5 mHz. Such contribution implies background excitations of acoustic-gravity waves in this frequency range. For direct detection of the background acoustic-gravity waves, our group conducted observations using an array of barometers [Nishida et al. 2005]. However, the spatial scale of the array of about 10 km was too small to detect acoustic modes below 10 mHz. Since then, no direct observations of these waves have been reported. In 2011, 337 high-resolution microbarometers were installed on a continental scale at USArray Transportable Array. The large and dense array enables us to detect the background atmospheric waves. Here, we show the first evidence of background Lamb waves in the Earth's atmosphere from 0.2 to 10 mHz, based on the array analysis of microbarometer data from the USArray in 2012. The observations suggest that the excitation sources are atmospheric disturbances in the troposphere. Theoretically, their energy in the troposphere tunnels into the thermosphere at a resonant frequency via thermospheric gravity wave, where the observed amplitudes indeed take a local minimum. The energy leak through the frequency window could partly contribute to thermospheric wave activity. Tropospheric disturbances exciting background Lamb waves may also be responsible for seismic hum at frequencies below 5 mHz.

The impact of land-surface wetness heterogeneity on mesoscale heat fluxes

NASA Technical Reports Server (NTRS)

Chen, Fei; Avissar, Roni

1994-01-01

Vertical heat fluxes associated with mesoscale circulations generated by land-surface wetness discontinuities are often stronger than turbulent fluxes, especially in the upper part of the atmospheric planetary boundary layer. As a result, they contribute significantly to the subgrid-scale fluxes in large-scale atmospheric models. Yet they are not considered in these models. To provide some insights into the possible parameterization of these fluxes in large-scale models, a state-of-the-art mesoscale numerical model was used to investigate the relationships between mesoscale heat fluxes and atmospheric and land-surface characteristics that play a key role in the generation of mesoscale circulations. The distribution of land-surface wetness, the wavenumber and the wavelength of the land-surface discontinuities, and the large-scale wind speed have a significant impact on the mesoscale heat fluxes. Empirical functions were derived to characterize the relationships between mesoscale heat fluxes and the spatial distribution of land-surface wetness. The strongest mesoscale heat fluxes were obtained for a wavelength of forcing corresponding approximately to the local Rossby deformation radius. The mesoscale heat fluxes are weakened by large-scale background winds but remain significant even with moderate winds.

Role of optometry school in single day large scale school vision testing

PubMed Central

Anuradha, N; Ramani, Krishnakumar

2015-01-01

Background: School vision testing aims at identification and management of refractive errors. Large-scale school vision testing using conventional methods is time-consuming and demands a lot of chair time from the eye care professionals. A new strategy involving a school of optometry in single day large scale school vision testing is discussed. Aim: The aim was to describe a new approach of performing vision testing of school children on a large scale in a single day. Materials and Methods: A single day vision testing strategy was implemented wherein 123 members (20 teams comprising optometry students and headed by optometrists) conducted vision testing for children in 51 schools. School vision testing included basic vision screening, refraction, frame measurements, frame choice and referrals for other ocular problems. Results: A total of 12448 children were screened, among whom 420 (3.37%) were identified to have refractive errors. 28 (1.26%) children belonged to the primary, 163 to middle (9.80%), 129 (4.67%) to secondary and 100 (1.73%) to the higher secondary levels of education respectively. 265 (2.12%) children were referred for further evaluation. Conclusion: Single day large scale school vision testing can be adopted by schools of optometry to reach a higher number of children within a short span. PMID:25709271

First detection of cosmic microwave background lensing and Lyman- α forest bispectrum

DOE PAGES

Doux, Cyrille; Schaan, Emmanuel; Aubourg, Eric; ...

2016-11-09

We present the first detection of a correlation between the Lyman-α forest and cosmic microwave background gravitational lensing. For each Lyman-α forest in SDSS-III/BOSS DR12, we correlate the one-dimensional power spectrum with the cosmic microwave background lensing convergence on the same line of sight from Planck. This measurement constitutes a position-dependent power spectrum, or a squeezed bispectrum, and quantifies the nonlinear response of the Lyman-α forest power spectrum to a large-scale overdensity. The signal is measured at 5σ and is consistent with the expectation of the standard ΛCDM cosmological model. We measure the linear bias of the Lyman-α forest withmore » respect to the dark matter distribution and constrain a combination of nonlinear terms including the nonlinear bias. This new observable provides a consistency check for the Lyman-α forest as a large-scale structure probe and tests our understanding of the relation between intergalactic gas and dark matter. In the future, it could be used to test hydrodynamical simulations and calibrate the relation between the Lyman-α forest and dark matter.« less

A study of environmental effects on galaxy spin using MaNGA data

NASA Astrophysics Data System (ADS)

Lee, Jong Chul; Hwang, Ho Seong; Chung, Haeun

2018-06-01

We investigate environmental effects on galaxy spin using the recent public data of Mapping Nearby Galaxies at APO (MaNGA) integral field spectroscopic survey containing ˜2800 galaxies. We measure the spin parameter of 1830 galaxies through the analysis of two-dimensional stellar kinematic maps within the effective radii, and obtain their large-scale (background mass density from 20 nearby galaxies) and small-scale (distance to and morphology of the nearest neighbour galaxy) environmental parameters for 1529 and 1767 galaxies, respectively. We first examine the mass dependence of galaxy spin, and find that the spin parameter of early-type galaxies decreases with stellar mass at log (M*/M⊙) ≳ 10, consistent with the results from previous studies. We then divide the galaxies into three subsamples using their stellar masses to minimize the mass effects on galaxy spin. The spin parameters of galaxies in each subsample do not change with background mass density, but do change with distance to and morphology of the nearest neighbour. In particular, the spin parameter of late-type galaxies decreases as early-type neighbours approach within the virial radius. These results suggest that the large-scale environments hardly affect the galaxy spin, but the small-scale environments such as hydrodynamic galaxy-galaxy interactions can play a substantial role in determining galaxy spin.

Readability versus Leveling.

ERIC Educational Resources Information Center

Fry, Edward

2002-01-01

Shows some similarities and differences between readability formulas and leveling procedures and reports some current large-scale uses of readability formulas. Presents a dictionary definition of readability and leveling, and a history and background of readability and leveling. Discusses what goes into determining readability and leveling scores.…

Large scale variation in DNA copy number in chicken breeds

USDA-ARS?s Scientific Manuscript database

Background Detecting genetic variation is a critical step in elucidating the molecular mechanisms underlying phenotypic diversity. Until recently, such detection has mostly focused on single nucleotide polymorphisms (SNPs) because of the ease in screening complete genomes. Another type of variant, c...

The universe at moderate redshift

NASA Technical Reports Server (NTRS)

Ostriker, Jeremiah P.

1992-01-01

The Final Report on the universe at moderate redshift covering the period from 1 Mar. 1988 to 28 Feb. 1991 is presented. Areas of research included: galaxy formation and large-scale structure; intergalactic medium and background radiation fields; quasar statistics and evolution; and gravitational lenses.

Background - oriented schlieren analysis of shockwave propagation from encased and uncased explosives

NASA Astrophysics Data System (ADS)

Romo, Cynthia Paulinne

High speed digital video images of encased and uncased large-scale explosions of Ammonium Nitrate Fuel Oil (ANFO), and Composition C-4 (C-4) at different masses were analyzed using the background oriented schlieren visualization technique. The encased explosions for ANFO and C-4 took place in the form of car bombs and pipe bombs respectively. The data obtained from the video footage were used to produce shock wave radius vs time profiles, as well as Mach number vs shock wave position profiles. The experimentally measured shock wave data for each explosive material were scaled using Sachs' scaling laws to a 1 kilogram charge at normal temperature and pressure. The results of C-4 were compared to literature, while the results of scaled ANFO were compared to each other, and to the results obtained during the uncased detonations. The comparison between the scaled profiles gathered from the encased and uncased detonations resulted in the identification of the relative amount of energy lost due to the fragmentation of the case. The C-4 profiles were compared to those obtained from computational simulations performed via CTH. The C-4 results showed an agreement in the data reported in literature and that obtained using the background-oriented schlieren (BOS) technique, as well as a good overall agreement with the profiles obtained computationally.

Interpretation of the cosmic microwave background radiation anisotropy detected by the COBE Differential Microwave Radiometer

NASA Technical Reports Server (NTRS)

Wright, E. L.; Meyer, S. S.; Bennett, C. L.; Boggess, N. W.; Cheng, E. S.; Hauser, M. G.; Kogut, A.; Lineweaver, C.; Mather, J. C.; Smoot, G. F.

1992-01-01

The large-scale cosmic background anisotropy detected by the COBE Differential Microwave Radiometer (DMR) instrument is compared to the sensitive previous measurements on various angular scales, and to the predictions of a wide variety of models of structure formation driven by gravitational instability. The observed anisotropy is consistent with all previously measured upper limits and with a number of dynamical models of structure formation. For example, the data agree with an unbiased cold dark matter (CDM) model with H0 = 50 km/s Mpc and Delta-M/M = 1 in a 16 Mpc radius sphere. Other models, such as CDM plus massive neutrinos (hot dark matter (HDM)), or CDM with a nonzero cosmological constant are also consistent with the COBE detection and can provide the extra power seen on 5-10,000 km/s scales.

Scale covariance and G-varying cosmology. II - Thermodynamics, radiation, and the 3 K background

NASA Technical Reports Server (NTRS)

Canuto, V. M.; Hsieh, S.-H.

1979-01-01

Within the framework of a scale-covariant theory of gravitation, a semiclassical description of particles and photons is given. Thermodynamic relations consistent with the modified conservation equations are derived. Application to a system of radiation shows that the observed 3-K background radiation can be interpreted, within the present framework, as a remnant of equilibrium radiation in the past. As the theory postulates a nonstandard coupling between gravitation and electrodynamics, the assumption that Einstein's theory of gravitation is unchanged forces modifications at the atomic level. The use of Minkowskian spacetime in atomic physics is found to be adequate only over small, but not large, time scales compared with the age of the universe. As a result, a relation between energy and the frequency of a free photon is demonstrated. Possible observational consequences of this relation are discussed.

Closing in on the large-scale CMB power asymmetry

NASA Astrophysics Data System (ADS)

Contreras, D.; Hutchinson, J.; Moss, A.; Scott, D.; Zibin, J. P.

2018-03-01

Measurements of the cosmic microwave background (CMB) temperature anisotropies have revealed a dipolar asymmetry in power at the largest scales, in apparent contradiction with the statistical isotropy of standard cosmological models. The significance of the effect is not very high, and is dependent on a posteriori choices. Nevertheless, a number of models have been proposed that produce a scale-dependent asymmetry. We confront several such models for a physical, position-space modulation with CMB temperature observations. We find that, while some models that maintain the standard isotropic power spectrum are allowed, others, such as those with modulated tensor or uncorrelated isocurvature modes, can be ruled out on the basis of the overproduction of isotropic power. This remains the case even when an extra isocurvature mode fully anticorrelated with the adiabatic perturbations is added to suppress power on large scales.

Large-scale structure after COBE: Peculiar velocities and correlations of cold dark matter halos

NASA Technical Reports Server (NTRS)

Zurek, Wojciech H.; Quinn, Peter J.; Salmon, John K.; Warren, Michael S.

1994-01-01

Large N-body simulations on parallel supercomputers allow one to simultaneously investigate large-scale structure and the formation of galactic halos with unprecedented resolution. Our study shows that the masses as well as the spatial distribution of halos on scales of tens of megaparsecs in a cold dark matter (CDM) universe with the spectrum normalized to the anisotropies detected by Cosmic Background Explorer (COBE) is compatible with the observations. We also show that the average value of the relative pairwise velocity dispersion sigma(sub v) - used as a principal argument against COBE-normalized CDM models-is significantly lower for halos than for individual particles. When the observational methods of extracting sigma(sub v) are applied to the redshift catalogs obtained from the numerical experiments, estimates differ significantly between different observation-sized samples and overlap observational estimates obtained following the same procedure.

Parallel Clustering Algorithm for Large-Scale Biological Data Sets

PubMed Central

Wang, Minchao; Zhang, Wu; Ding, Wang; Dai, Dongbo; Zhang, Huiran; Xie, Hao; Chen, Luonan; Guo, Yike; Xie, Jiang

2014-01-01

Backgrounds Recent explosion of biological data brings a great challenge for the traditional clustering algorithms. With increasing scale of data sets, much larger memory and longer runtime are required for the cluster identification problems. The affinity propagation algorithm outperforms many other classical clustering algorithms and is widely applied into the biological researches. However, the time and space complexity become a great bottleneck when handling the large-scale data sets. Moreover, the similarity matrix, whose constructing procedure takes long runtime, is required before running the affinity propagation algorithm, since the algorithm clusters data sets based on the similarities between data pairs. Methods Two types of parallel architectures are proposed in this paper to accelerate the similarity matrix constructing procedure and the affinity propagation algorithm. The memory-shared architecture is used to construct the similarity matrix, and the distributed system is taken for the affinity propagation algorithm, because of its large memory size and great computing capacity. An appropriate way of data partition and reduction is designed in our method, in order to minimize the global communication cost among processes. Result A speedup of 100 is gained with 128 cores. The runtime is reduced from serval hours to a few seconds, which indicates that parallel algorithm is capable of handling large-scale data sets effectively. The parallel affinity propagation also achieves a good performance when clustering large-scale gene data (microarray) and detecting families in large protein superfamilies. PMID:24705246

Radon background in liquid xenon detectors

NASA Astrophysics Data System (ADS)

Rupp, N.

2018-02-01

The radioactive daughters isotope of 222Rn are one of the highest risk contaminants in liquid xenon detectors aiming for a small signal rate. The noble gas is permanently emanated from the detector surfaces and mixed with the xenon target. Because of its long half-life 222Rn is homogeneously distributed in the target and its subsequent decays can mimic signal events. Since no shielding is possible this background source can be the dominant one in future large scale experiments. This article provides an overview of strategies used to mitigate this source of background by means of material selection and on-line radon removal techniques.

Probing pre-inflationary anisotropy with directional variations in the gravitational wave background

DOE Office of Scientific and Technical Information (OSTI.GOV)

Furuya, Yu; Niiyama, Yuki; Sendouda, Yuuiti, E-mail: furuya@tap.st.hirosaki-u.ac.jp, E-mail: niiyama@tap.st.hirosaki-u.ac.jp, E-mail: sendouda@hirosaki-u.ac.jp

We perform a detailed analysis on a primordial gravitational-wave background amplified during a Kasner-like pre-inflationary phase allowing for general triaxial anisotropies. It is found that the predicted angular distribution map of gravitational-wave intensity on large scales exhibits topologically distinctive patterns according to the degree of the pre-inflationary anisotropy, thereby serving as a potential probe for the pre-inflationary early universe with future all-sky observations of gravitational waves. We also derive an observational limit on the amplitude of such anisotropic gravitational waves from the B -mode polarisation of the cosmic microwave background.

Correlated perturbations from inflation and the cosmic microwave background.

PubMed

Amendola, Luca; Gordon, Christopher; Wands, David; Sasaki, Misao

2002-05-27

We compare the latest cosmic microwave background data with theoretical predictions including correlated adiabatic and cold dark matter (CDM) isocurvature perturbations with a simple power-law dependence. We find that there is a degeneracy between the amplitude of correlated isocurvature perturbations and the spectral tilt. A negative (red) tilt is found to be compatible with a larger isocurvature contribution. Estimates of the baryon and CDM densities are found to be almost independent of the isocurvature amplitude. The main result is that current microwave background data do not exclude a dominant contribution from CDM isocurvature fluctuations on large scales.

Cosmic Infrared Background Fluctuations and Zodiacal Light

NASA Technical Reports Server (NTRS)

Arendt, Richard G.; Kashlinsky, A.; Moseley, S. H.; Mather, J.

2017-01-01

We performed a specific observational test to measure the effect that the zodiacal light can have on measurements of the spatial fluctuations of the near-IR (near-infrared)background. Previous estimates of possible fluctuations caused by zodiacal light have often been extrapolated from observations of the thermal emission at longer wavelengths and low angular resolution or from IRAC (Infrared Array Camera) observations of high-latitude fields where zodiacal light is faint and not strongly varying with time. The new observations analyzed here target the COSMOS (Cosmic Evolution Survey) field at low ecliptic latitude where the zodiacal light intensity varies by factors of approximately 2 over the range of solar elongations at which the field can be observed. We find that the white-noise component of the spatial power spectrum of the background is correlated with the modeled zodiacal light intensity. Roughly half of the measured white noise is correlated with the zodiacal light, but a more detailed interpretation of the white noise is hampered by systematic uncertainties that are evident in the zodiacal light model. At large angular scales (greater than or approximately equal to 100 arcseconds) where excess power above the white noise is observed, we find no correlation of the power with the modeled intensity of the zodiacal light. This test clearly indicates that the large-scale power in the infrared background is not being caused by the zodiacal light.

Stellar granulation as seen in disk-integrated intensity. II. Theoretical scaling relations compared with observations

NASA Astrophysics Data System (ADS)

Samadi, R.; Belkacem, K.; Ludwig, H.-G.; Caffau, E.; Campante, T. L.; Davies, G. R.; Kallinger, T.; Lund, M. N.; Mosser, B.; Baglin, A.; Mathur, S.; Garcia, R. A.

2013-11-01

Context. A large set of stars observed by CoRoT and Kepler shows clear evidence for the presence of a stellar background, which is interpreted to arise from surface convection, i.e., granulation. These observations show that the characteristic time-scale (τeff) and the root-mean-square (rms) brightness fluctuations (σ) associated with the granulation scale as a function of the peak frequency (νmax) of the solar-like oscillations. Aims: We aim at providing a theoretical background to the observed scaling relations based on a model developed in Paper I. Methods: We computed for each 3D model the theoretical power density spectrum (PDS) associated with the granulation as seen in disk-integrated intensity on the basis of the theoretical model published in Paper I. For each PDS we derived the associated characteristic time (τeff) and the rms brightness fluctuations (σ) and compared these theoretical values with the theoretical scaling relations derived from the theoretical model and the measurements made on a large set of Kepler targets. Results: We derive theoretical scaling relations for τeff and σ, which show the same dependence on νmax as the observed scaling relations. In addition, we show that these quantities also scale as a function of the turbulent Mach number (ℳa) estimated at the photosphere. The theoretical scaling relations for τeff and σ match the observations well on a global scale. Quantitatively, the remaining discrepancies with the observations are found to be much smaller than previous theoretical calculations made for red giants. Conclusions: Our modelling provides additional theoretical support for the observed variations of σ and τeff with νmax. It also highlights the important role of ℳa in controlling the properties of the stellar granulation. However, the observations made with Kepler on a wide variety of stars cannot confirm the dependence of our scaling relations on ℳa. Measurements of the granulation background and detections of solar-like oscillations in a statistically sufficient number of cool dwarf stars will be required for confirming the dependence of the theoretical scaling relations with ℳa. Appendices are available in electronic form at http://www.aanda.org

The gravitational wave contribution to cosmic microwave background anisotropies and the amplitude of mass fluctuations from COBE results

NASA Technical Reports Server (NTRS)

Lucchin, Francesco; Matarrese, Sabino; Mollerach, Silvia

1992-01-01

A stochastic background of primordial gravitational waves may substantially contribute, via the Sachs-Wolfe effect, to the large-scale cosmic microwave background (CMB) anisotropies recently detected by COBE. This implies a bias in any resulting determination of the primordial amplitude of density fluctuations. We consider the constraints imposed on n is less than 1 ('tilted') power-law fluctuation spectra, taking into account the contribution from both scalar and tensor waves, as predicted by power-law inflation. The gravitational wave contribution to CMB anisotropies generally reduces the required rms level of mass fluctuation, thereby increasing the linear bias parameter, even in models where the spectral index is close to the Harrison-Zel'dovich value n = 1. This 'gravitational wave bias' helps to reconcile the predictions of CDM models with observations on pairwise galaxy velocity dispersion on small scales.

Impacts of wildfire smoke plumes on regional air quality

EPA Science Inventory

Background: Recent trends in increased frequency and severity of large fires necessitate an improved understanding of smoke plume impacts on regional-scale air quality and public health. Objective: We examine the impact of fire smoke on regional air quality between 2006 and 2013 ...

Surface ozone at the Swiss Alpine site Arosa: the hemispheric background and the influence of large-scale anthropogenic emissions

NASA Astrophysics Data System (ADS)

Pochanart, Pakpong; Akimoto, Hajime; Maksyutov, Shamil; Staehelin, Johannes

An innovative and effective method using isentropic trajectory analysis based on the residence time of air masses over the polluted region of Europe was successfully applied to categorize surface ozone amounts at Arosa, Switzerland during 1996-1997. The "European representative" background ozone seasonal cycle at Arosa is associated with long-range transport of North Atlantic air masses, and displays the spring maximum-summer minimum with an annual average of 35 ppb. The photochemical ozone production due to the intense large-scale anthropogenic emission over Europe is estimated as high as 20 ppb in summer, whereas it is insignificant in winter. European sources contribute an annual net ozone production of 9-12 ppb at Arosa. Comparison with the selected regional representative site in Western Europe shows similar results indicating that the categorized ozone data at Arosa by this technique could be regarded as a representative for northern hemispheric mid-latitudes.

The amplitude and spectral index of the large angular scale anisotropy in the cosmic microwave background radiation

NASA Technical Reports Server (NTRS)

Ganga, Ken; Page, Lyman; Cheng, Edward; Meyer, Stephan

1994-01-01

In many cosmological models, the large angular scale anisotropy in the cosmic microwave background is parameterized by a spectral index, n, and a quadrupolar amplitude, Q. For a Harrison-Peebles-Zel'dovich spectrum, n = 1. Using data from the Far Infrared Survey (FIRS) and a new statistical measure, a contour plot of the likelihood for cosmological models for which -1 less than n less than 3 and 0 equal to or less than Q equal to or less than 50 micro K is obtained. Depending upon the details of the analysis, the maximum likelihood occurs at n between 0.8 and 1.4 and Q between 18 and 21 micro K. Regardless of Q, the likelihood is always less than half its maximum for n less than -0.4 and for n greater than 2.2, as it is for Q less than 8 micro K and Q greater than 44 micro K.

Scale dependence of the alignment between strain rate and rotation in turbulent shear flow

NASA Astrophysics Data System (ADS)

Fiscaletti, D.; Elsinga, G. E.; Attili, A.; Bisetti, F.; Buxton, O. R. H.

2016-10-01

The scale dependence of the statistical alignment tendencies of the eigenvectors of the strain-rate tensor ei, with the vorticity vector ω , is examined in the self-preserving region of a planar turbulent mixing layer. Data from a direct numerical simulation are filtered at various length scales and the probability density functions of the magnitude of the alignment cosines between the two unit vectors | ei.ω ̂| are examined. It is observed that the alignment tendencies are insensitive to the concurrent large-scale velocity fluctuations, but are quantitatively affected by the nature of the concurrent large-scale velocity-gradient fluctuations. It is confirmed that the small-scale (local) vorticity vector is preferentially aligned in parallel with the large-scale (background) extensive strain-rate eigenvector e1, in contrast to the global tendency for ω to be aligned in parallel with the intermediate strain-rate eigenvector [Hamlington et al., Phys. Fluids 20, 111703 (2008), 10.1063/1.3021055]. When only data from regions of the flow that exhibit strong swirling are included, the so-called high-enstrophy worms, the alignment tendencies are exaggerated with respect to the global picture. These findings support the notion that the production of enstrophy, responsible for a net cascade of turbulent kinetic energy from large scales to small scales, is driven by vorticity stretching due to the preferential parallel alignment between ω and nonlocal e1 and that the strongly swirling worms are kinematically significant to this process.

Spatial and Temporal Dynamics of Pacific Oyster Hemolymph Microbiota across Multiple Scales

PubMed Central

Lokmer, Ana; Goedknegt, M. Anouk; Thieltges, David W.; Fiorentino, Dario; Kuenzel, Sven; Baines, John F.; Wegner, K. Mathias

2016-01-01

Unveiling the factors and processes that shape the dynamics of host associated microbial communities (microbiota) under natural conditions is an important part of understanding and predicting an organism's response to a changing environment. The microbiota is shaped by host (i.e., genetic) factors as well as by the biotic and abiotic environment. Studying natural variation of microbial community composition in multiple host genetic backgrounds across spatial as well as temporal scales represents a means to untangle this complex interplay. Here, we combined a spatially-stratified with a longitudinal sampling scheme within differentiated host genetic backgrounds by reciprocally transplanting Pacific oysters between two sites in the Wadden Sea (Sylt and Texel). To further differentiate contingent site from host genetic effects, we repeatedly sampled the same individuals over a summer season to examine structure, diversity and dynamics of individual hemolymph microbiota following experimental removal of resident microbiota by antibiotic treatment. While a large proportion of microbiome variation could be attributed to immediate environmental conditions, we observed persistent effects of antibiotic treatment and translocation suggesting that hemolymph microbial community dynamics is subject to within-microbiome interactions and host population specific factors. In addition, the analysis of spatial variation revealed that the within-site microenvironmental heterogeneity resulted in high small-scale variability, as opposed to large-scale (between-site) stability. Similarly, considerable within-individual temporal variability was in contrast with the overall temporal stability at the site level. Overall, our longitudinal, spatially-stratified sampling design revealed that variation in hemolymph microbiota is strongly influenced by site and immediate environmental conditions, whereas internal microbiome dynamics and oyster-related factors add to their long-term stability. The combination of small and large scale resolution of spatial and temporal observations therefore represents a crucial but underused tool to study host-associated microbiome dynamics. PMID:27630625

A measurement of the large-scale cosmic microwave background anisotropy at 1.8 millimeter wavelength

NASA Technical Reports Server (NTRS)

Meyer, Stephan S.; Cheng, Edward S.; Page, Lyman A.

1991-01-01

This measurement of the large-scale cosmic microwave background radiation (CMBR) anisotropy places the most stringent constraints to date on fluctuations in the CMBR on angular scales greater than about 4 deg. Using a four-channel bolometric radiometer operating at 1.8, 1.1, 0.63, and 0.44 mm, the diffuse sky brightness over half of the northern hemisphere has been mapped with an angular resolution of 3.8 deg. Analysis of the sky map at the longest wavelength for Galactic latitudes of 15 deg or more yields a 95-percent confidence level upper limit on fluctuations of the CMBR at Delta T/T of 1.6 x 10 to the -5th with a statistical power of 92 percent for Gaussian fluctuations at a correlation angle of 13 deg. Between 3 deg and 22 deg, the upper limit of fluctuations is 4.0 x 10 to the -5th . An anisotropy is detected in the map, but it cannot yet be attributed to primordial sources. The ultimate sensitivity for this experiment is 7 x 10 to the -6th over this angular range for Gaussian fluctuations.

Background derivation and image flattening: getimages

NASA Astrophysics Data System (ADS)

Men'shchikov, A.

2017-11-01

Modern high-resolution images obtained with space observatories display extremely strong intensity variations across images on all spatial scales. Source extraction in such images with methods based on global thresholding may bring unacceptably large numbers of spurious sources in bright areas while failing to detect sources in low-background or low-noise areas. It would be highly beneficial to subtract background and equalize the levels of small-scale fluctuations in the images before extracting sources or filaments. This paper describes getimages, a new method of background derivation and image flattening. It is based on median filtering with sliding windows that correspond to a range of spatial scales from the observational beam size up to a maximum structure width Xλ. The latter is a single free parameter of getimages that can be evaluated manually from the observed image ℐλ. The median filtering algorithm provides a background image \\tilde{Bλ} for structures of all widths below Xλ. The same median filtering procedure applied to an image of standard deviations 𝓓λ derived from a background-subtracted image \\tilde{Sλ} results in a flattening image \\tilde{Fλ}. Finally, a flattened detection image I{λD} = \\tilde{Sλ}/\\tilde{Fλ} is computed, whose standard deviations are uniform outside sources and filaments. Detecting sources in such greatly simplified images results in much cleaner extractions that are more complete and reliable. As a bonus, getimages reduces various observational and map-making artifacts and equalizes noise levels between independent tiles of mosaicked images.

Multi-Scale Three-Dimensional Variational Data Assimilation System for Coastal Ocean Prediction

NASA Technical Reports Server (NTRS)

Li, Zhijin; Chao, Yi; Li, P. Peggy

2012-01-01

A multi-scale three-dimensional variational data assimilation system (MS-3DVAR) has been formulated and the associated software system has been developed for improving high-resolution coastal ocean prediction. This system helps improve coastal ocean prediction skill, and has been used in support of operational coastal ocean forecasting systems and field experiments. The system has been developed to improve the capability of data assimilation for assimilating, simultaneously and effectively, sparse vertical profiles and high-resolution remote sensing surface measurements into coastal ocean models, as well as constraining model biases. In this system, the cost function is decomposed into two separate units for the large- and small-scale components, respectively. As such, data assimilation is implemented sequentially from large to small scales, the background error covariance is constructed to be scale-dependent, and a scale-dependent dynamic balance is incorporated. This scheme then allows effective constraining large scales and model bias through assimilating sparse vertical profiles, and small scales through assimilating high-resolution surface measurements. This MS-3DVAR enhances the capability of the traditional 3DVAR for assimilating highly heterogeneously distributed observations, such as along-track satellite altimetry data, and particularly maximizing the extraction of information from limited numbers of vertical profile observations.

Detectability of large-scale power suppression in the galaxy distribution

NASA Astrophysics Data System (ADS)

Gibelyou, Cameron; Huterer, Dragan; Fang, Wenjuan

2010-12-01

Suppression in primordial power on the Universe’s largest observable scales has been invoked as a possible explanation for large-angle observations in the cosmic microwave background, and is allowed or predicted by some inflationary models. Here we investigate the extent to which such a suppression could be confirmed by the upcoming large-volume redshift surveys. For definiteness, we study a simple parametric model of suppression that improves the fit of the vanilla ΛCDM model to the angular correlation function measured by WMAP in cut-sky maps, and at the same time improves the fit to the angular power spectrum inferred from the maximum likelihood analysis presented by the WMAP team. We find that the missing power at large scales, favored by WMAP observations within the context of this model, will be difficult but not impossible to rule out with a galaxy redshift survey with large-volume (˜100Gpc3). A key requirement for success in ruling out power suppression will be having redshifts of most galaxies detected in the imaging survey.

Removal of two large-scale cosmic microwave background anomalies after subtraction of the integrated Sachs-Wolfe effect

NASA Astrophysics Data System (ADS)

Rassat, A.; Starck, J.-L.; Dupé, F.-X.

2013-09-01

Context. Although there is currently a debate over the significance of the claimed large-scale anomalies in the cosmic microwave background (CMB), their existence is not totally dismissed. In parallel to the debate over their statistical significance, recent work has also focussed on masks and secondary anisotropies as potential sources of these anomalies. Aims: In this work we investigate simultaneously the impact of the method used to account for masked regions as well as the impact of the integrated Sachs-Wolfe (ISW) effect, which is the large-scale secondary anisotropy most likely to affect the CMB anomalies. In this sense, our work is an update of previous works. Our aim is to identify trends in CMB data from different years and with different mask treatments. Methods: We reconstruct the ISW signal due to 2 Micron All-Sky Survey (2MASS) and NRAO VLA Sky Survey (NVSS) galaxies, effectively reconstructing the low-redshift ISW signal out to z ~ 1. We account for regions of missing data using the sparse inpainting technique. We test sparse inpainting of the CMB, large scale structure and ISW and find that it constitutes a bias-free reconstruction method suitable to study large-scale statistical isotropy and the ISW effect. Results: We focus on three large-scale CMB anomalies: the low quadrupole, the quadrupole/octopole alignment, and the octopole planarity. After sparse inpainting, the low quadrupole becomes more anomalous, whilst the quadrupole/octopole alignment becomes less anomalous. The significance of the low quadrupole is unchanged after subtraction of the ISW effect, while the trend amongst the CMB maps is that both the low quadrupole and the quadrupole/octopole alignment have reduced significance, yet other hypotheses remain possible as well (e.g. exotic physics). Our results also suggest that both of these anomalies may be due to the quadrupole alone. While the octopole planarity significance is reduced after inpainting and after ISW subtraction, however, we do not find that it was very anomalous to start with. In the spirit of participating in reproducible research, we make all codes and resulting products which constitute main results of this paper public here: http://www.cosmostat.org/anomaliesCMB.html

The LAMAR: A high throughput X-ray astronomy facility for a moderate cost mission

NASA Technical Reports Server (NTRS)

Gorenstein, P.; Schwartz, D.

1981-01-01

The performance of a large area modular array of reflectors (LAMAR) is considered in several hypothetical observations relevant to: (1) cosmology, the X-ray background, and large scale structure of the universe; (2) clusters of galaxies and their evolution; (3) quasars and other active galactic nuclei; (4) compact objects in our galaxy; (5) stellar coronae; and (6) energy input to the interstellar medium.

Quadratic integrand double-hybrid made spin-component-scaled

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brémond, Éric, E-mail: eric.bremond@iit.it; Savarese, Marika; Sancho-García, Juan C.

2016-03-28

We propose two analytical expressions aiming to rationalize the spin-component-scaled (SCS) and spin-opposite-scaled (SOS) schemes for double-hybrid exchange-correlation density-functionals. Their performances are extensively tested within the framework of the nonempirical quadratic integrand double-hybrid (QIDH) model on energetic properties included into the very large GMTKN30 benchmark database, and on structural properties of semirigid medium-sized organic compounds. The SOS variant is revealed as a less computationally demanding alternative to reach the accuracy of the original QIDH model without losing any theoretical background.

Thick strings, the liquid crystal blue phase, and cosmological large-scale structure

NASA Technical Reports Server (NTRS)

Luo, Xiaochun; Schramm, David N.

1992-01-01

A phenomenological model based on the liquid crystal blue phase is proposed as a model for a late-time cosmological phase transition. Topological defects, in particular thick strings and/or domain walls, are presented as seeds for structure formation. It is shown that the observed large-scale structure, including quasi-periodic wall structure, can be well fitted in the model without violating the microwave background isotropy bound or the limits from induced gravitational waves and the millisecond pulsar timing. Furthermore, such late-time transitions can produce objects such as quasars at high redshifts. The model appears to work with either cold or hot dark matter.

Litmus Test for Cosmic Hemispherical Asymmetry in the Cosmic Microwave Background B -Mode Polarization

NASA Astrophysics Data System (ADS)

Mukherjee, Suvodip; Souradeep, Tarun

2016-06-01

Recent measurements of the temperature field of the cosmic microwave background (CMB) provide tantalizing evidence for violation of statistical isotropy (SI) that constitutes a fundamental tenet of contemporary cosmology. CMB space based missions, WMAP, and Planck have observed a 7% departure in the SI temperature field at large angular scales. However, due to higher cosmic variance at low multipoles, the significance of this measurement is not expected to improve from any future CMB temperature measurements. We demonstrate that weak lensing of the CMB due to scalar perturbations produces a corresponding SI violation in B modes of CMB polarization at smaller angular scales. The measurability of this phenomenon depends upon the scales (l range) over which power asymmetry is present. Power asymmetry, which is restricted only to l <64 in the temperature field, cannot lead to any significant observable effect from this new window. However, this effect can put an independent bound on the spatial range of scales of hemispherical asymmetry present in the scalar sector.

Litmus Test for Cosmic Hemispherical Asymmetry in the Cosmic Microwave Background B-Mode Polarization.

PubMed

Mukherjee, Suvodip; Souradeep, Tarun

2016-06-03

Recent measurements of the temperature field of the cosmic microwave background (CMB) provide tantalizing evidence for violation of statistical isotropy (SI) that constitutes a fundamental tenet of contemporary cosmology. CMB space based missions, WMAP, and Planck have observed a 7% departure in the SI temperature field at large angular scales. However, due to higher cosmic variance at low multipoles, the significance of this measurement is not expected to improve from any future CMB temperature measurements. We demonstrate that weak lensing of the CMB due to scalar perturbations produces a corresponding SI violation in B modes of CMB polarization at smaller angular scales. The measurability of this phenomenon depends upon the scales (l range) over which power asymmetry is present. Power asymmetry, which is restricted only to l<64 in the temperature field, cannot lead to any significant observable effect from this new window. However, this effect can put an independent bound on the spatial range of scales of hemispherical asymmetry present in the scalar sector.

CLASS: The Cosmology Large Angular Scale Surveyor

NASA Technical Reports Server (NTRS)

Essinger-Hileman, Thomas; Ali, Aamir; Amiri, Mandana; Appel, John W.; Araujo, Derek; Bennett, Charles L.; Boone, Fletcher; Chan, Manwei; Cho, Hsiao-Mei; Chuss, David T.;

The study of integration about measurable image and 4D production

NASA Astrophysics Data System (ADS)

Zhang, Chunsen; Hu, Pingbo; Niu, Weiyun

2008-12-01

In this paper, we create the geospatial data of three-dimensional (3D) modeling by the combination of digital photogrammetry and digital close-range photogrammetry. For large-scale geographical background, we make the establishment of DEM and DOM combination of three-dimensional landscape model based on the digital photogrammetry which uses aerial image data to make "4D" (DOM: Digital Orthophoto Map, DEM: Digital Elevation Model, DLG: Digital Line Graphic and DRG: Digital Raster Graphic) production. For the range of building and other artificial features which the users are interested in, we realize that the real features of the three-dimensional reconstruction adopting the method of the digital close-range photogrammetry can come true on the basis of following steps : non-metric cameras for data collection, the camera calibration, feature extraction, image matching, and other steps. At last, we combine three-dimensional background and local measurements real images of these large geographic data and realize the integration of measurable real image and the 4D production.The article discussed the way of the whole flow and technology, achieved the three-dimensional reconstruction and the integration of the large-scale threedimensional landscape and the metric building.

Scaling beta-delayed neutron measurements to large detector areas

NASA Astrophysics Data System (ADS)

Sutanto, F.; Nattress, J.; Jovanovic, I.

2017-08-01

We explore the performance of a cargo screening system that consists of two large-sized composite scintillation detectors and a high-energy neutron interrogation source by modeling and simulation. The goal of the system is to measure β-delayed neutron emission from an illicit special nuclear material by use of active interrogation. This task is challenging because the β-delayed neutron yield is small in comparison with the yield of the prompt fission secondary products, β-delayed neutrons are emitted with relatively low energies, and high neutron and gamma backgrounds are typically present. Detectors used to measure delayed neutron emission must exhibit high intrinsic efficiency and cover a large solid angle, which also makes them sensitive to background neutron radiation. We present a case study where we attempt to detect the presence of 5 kg-scale quantities of 235U in a standard air-filled cargo container using 14 MeV neutrons as a probe. We find that by using a total measurement time of ˜11.6 s and a dose equivalent of ˜1.7 mrem, the presence of 235U can be detected with false positive and false negative probabilities that are both no larger than 0.1%.

Maser radiometer for cosmic background radiation anisotropy measurements

NASA Technical Reports Server (NTRS)

Fixsen, D. J.; Wilkinson, D. T.

1982-01-01

A maser amplifier was incorporated into a low noise radiometer designed to measure large-scale anisotropy in the 3 deg K microwave background radiation. To minimize emission by atmospheric water vapor and oxygen, the radiometer is flown in a small balloon to an altitude to 25 km. Three successful flights were made - two from Palestine, Texas and one from Sao Jose dos Campos, Brazil. Good sky coverage is important to the experiment. Data from the northern hemisphere flights has been edited and calibrated.

The impact of radiatively active water-ice clouds on Martian mesoscale atmospheric circulations

NASA Astrophysics Data System (ADS)

Spiga, A.; Madeleine, J.-B.; Hinson, D.; Navarro, T.; Forget, F.

2014-04-01

Background and Goals Water ice clouds are a key component of the Martian climate [1]. Understanding the properties of the Martian water ice clouds is crucial to constrain the Red Planet's climate and hydrological cycle both in the present and in the past [2]. In recent years, this statement have become all the more true as it was shown that the radiative effects of water ice clouds is far from being as negligible as hitherto believed; water ice clouds plays instead a key role in the large-scale thermal structure and dynamics of the Martian atmosphere [3, 4, 5]. Nevertheless, the radiative effect of water ice clouds at lower scales than the large synoptic scale (the so-called meso-scales) is still left to be explored. Here we use for the first time mesoscale modeling with radiatively active water ice clouds to address this open question.

[General background and practical implementation of the health management service institution in Korea].

PubMed

Okahara, Shintaro; Lee, Byeong-Woo; Ogasawara, Takayuki; Mori, Koji

2014-09-01

The Korean Occupational Safety and Health Act requires an employer with more than 50 employees to assign a health manager or an occupational physician. However, there are many cases where it is difficult for medium-scale enterprises to perform occupational health practices autonomously because their financial base is weaker than that of large-scale enterprises. The Korean Occupational Safety and Health Act was amended in 1990 so that medium-scale enterprises could entrust a health management service institution with their health management tasks. This system is similar to the outsourcing of medical examinations, occupational physicians, or the measurement of the working environment in Japan, but its legal background and actual activities are korea-specific, and it has some different points. In particular, the quality control of health management service institutions by legal and administrative regulations, and the multidisciplinary provision of services contribute to the development of occupational health in medium-scale enterprises. This will be a good reference for occupational health services in small- and medium-scale enterprises in the future in Japan.

What initial condition of inflation would suppress the large-scale CMB spectrum?

DOE PAGES

Chen, Pisin; Lin, Yu -Hsiang

2016-01-08

There is an apparent power deficit relative to the Λ CDM prediction of the cosmic microwave background spectrum at large scales, which, though not yet statistically significant, persists from WMAP to Planck data. Proposals that invoke some form of initial condition for the inflation have been made to address this apparent power suppression, albeit with conflicting conclusions. By studying the curvature perturbations of a scalar field in the Friedmann-Lemaître-Robertson-Walker universe parameterized by the equation of state parameter w, we find that the large-scale spectrum at the end of inflation reflects the superhorizon spectrum of the initial state. The large-scale spectrummore » is suppressed if the universe begins with the adiabatic vacuum in a superinflation (w < –1) or positive-pressure (w > 0) era. In the latter case, there is however no causal mechanism to establish the initial adiabatic vacuum. On the other hand, as long as the universe begins with the adiabatic vacuum in an era with –1 < w < 0, even if there exists an intermediate positive-pressure era, the large-scale spectrum would be enhanced rather than suppressed. In conclusion, we further calculate the spectrum of a two-stage inflation model with a two-field potential and show that the result agrees with that obtained from the ad hoc single-field analysis.« less

Examples of backreaction of small-scale inhomogeneities in cosmology

NASA Astrophysics Data System (ADS)

Green, Stephen R.; Wald, Robert M.

2013-06-01

In previous work, we introduced a new framework to treat large-scale backreaction effects due to small-scale inhomogeneities in general relativity. We considered one-parameter families of spacetimes for which such backreaction effects can occur, and we proved that, provided the weak energy condition on matter is satisfied, the leading effect of small-scale inhomogeneities on large-scale dynamics is to produce a traceless effective stress-energy tensor that itself satisfies the weak energy condition. In this work, we illustrate the nature of our framework by providing two explicit examples of one-parameter families with backreaction. The first, based on previous work of Berger, is a family of polarized vacuum Gowdy spacetimes on a torus, which satisfies all of the assumptions of our framework. As the parameter approaches its limiting value, the metric uniformly approaches a smooth background metric, but spacetime derivatives of the deviation of the metric from the background metric do not converge uniformly to zero. The limiting metric has nontrivial backreaction from the small-scale inhomogeneities, with an effective stress energy that is traceless and satisfies the weak energy condition, in accord with our theorems. Our second one-parameter family consists of metrics which have a uniform Friedmann-Lemaître-Robertson-Walker limit. This family satisfies all of our assumptions with the exception of the weak energy condition for matter. In this case, the limiting metric has an effective stress-energy tensor which is not traceless. We emphasize the importance of imposing energy conditions on matter in studies of backreaction.

A Search for Hot, Diffuse Gas in Superclusters

NASA Technical Reports Server (NTRS)

Boughn, Stephen P.

1998-01-01

The HEA01 A2 full sky, 2-10 keV X-ray map was searched for diffuse emission correlated with the plane of the local supercluster of galaxies and a positive correlation was found at the 99% confidence level. The most obvious interpretation is that the local supercluster contains a substantial amount of hot (10(exp 8) OK), diffuse gas, i.e. ionized hydrogen, with a density on the order of 2 - 3 x 10(exp -6) ions per cubic centimeter. This density is about an order of magnitude larger than the average baryon density of the universe and is consistent with a supercluster collapse factor of 10. The implied total mass is of the order of 10(exp 16) times the mass of the sun and would constitute a large fraction of the baryonic matter in the local universe. This result supports current thinking that most of the ordinary matter in the universe is in the form of ionized hydrogen; however, the high temperature implied by the X-ray emission is at the top of the range predicted by most theories. The presence of a large amount of hot gas would leave its imprint on the Cosmic Microwave Background (CMB) via the Sunyaev-Zel'dovich (SZ) effect. A marginal decrement (-17 muK) was found in the COBE 4-year 53 GHz CMB map coincident with the plane of the local supercluster. Although the detection is only 1beta, the level is consistent with the SZ effect predicted from the hot gas. If these results are confirmed by future observations they will have important implications for the formation of large-scale structure in the universe. Three other projects related directly to the HEAO 1 map or the X-ray background in general benefited from this NASA grant. They are: (1) "Correlations between the Cosmic X-ray and Microwave Backgrounds: Constraints on a Cosmological Constant"; (2) "Cross-correlation of the X-ray Background with Radio Sources: Constraining the Large-Scale Structure of the X-ray Background"; and (3) "Radio and X-ray Emission Mechanisms in Advection Dominated Accretion Flow".

Cosmic void clumps

NASA Astrophysics Data System (ADS)

Lares, M.; Luparello, H. E.; Garcia Lambas, D.; Ruiz, A. N.; Ceccarelli, L.; Paz, D.

2017-10-01

Cosmic voids are of great interest given their relation to the large scale distribution of mass and the way they trace cosmic flows shaping the cosmic web. Here we show that the distribution of voids has, in consonance with the distribution of mass, a characteristic scale at which void pairs are preferentially located. We identify clumps of voids with similar environments and use them to define second order underdensities. Also, we characterize its properties and analyze its impact on the cosmic microwave background.

Disseminating a clinically effective physical activity program to preserve mobility in a community setting for older adults

USDA-ARS?s Scientific Manuscript database

Background: As the population of older adults continues to increase, the dissemination of strategies to maintain independence of older persons is of critical public health importance. Recent large-scale clinical trial evidence has definitively shown intervention of moderate-intensity physical activi...

Computers in Electrical Engineering Education at Virginia Polytechnic Institute.

ERIC Educational Resources Information Center

Bennett, A. Wayne

1982-01-01

Discusses use of computers in Electrical Engineering (EE) at Virginia Polytechnic Institute. Topics include: departmental background, level of computing power using large scale systems, mini and microcomputers, use of digital logic trainers and analog/hybrid computers, comments on integrating computers into EE curricula, and computer use in…

Initiating a National Coaching Curriculum: A Paradigmatic Shift?

ERIC Educational Resources Information Center

Cassidy, Tania; Kidman, Lynn

2010-01-01

Background: A number of countries have heavily invested in the provision of large scale coach education programmes, often framed by elaborate qualification frameworks. Despite this investment, scant research has been conducted on coach education programmes. Given the limited amount of literature on coach education, and the relatively recent…

The Dynamics of Smoking-Related Disturbed Methylation: A Two Time-Point Study of Methylation Change in Smokers, Non-Smokers and Former Smokers

EPA Science Inventory

BACKGROUND: The evidence for epigenome-wide associations between smoking and DNA methylation continues to grow through cross-sectional studies. However, few large­ scale investigations have explored the associations using observations for individuals at multiple time-points. ...

Using National Coastal Assessment Data to Model Estuarine Water Quality at Large Spatial Scales

EPA Science Inventory

Background/Question/MethodThe water quality of the Nation’s estuaries is attracting increasing scrutiny in light of burgeoning coastal population growth and enhanced delivery of nutrients via riverine flux. The USEPA has evaluated water quality in US estuaries in the Nation...

An ensemble constrained variational analysis of atmospheric forcing data and its application to evaluate clouds in CAM5: Ensemble 3DCVA and Its Application

DOE PAGES

Tang, Shuaiqi; Zhang, Minghua; Xie, Shaocheng

2016-01-05

Large-scale atmospheric forcing data can greatly impact the simulations of atmospheric process models including Large Eddy Simulations (LES), Cloud Resolving Models (CRMs) and Single-Column Models (SCMs), and impact the development of physical parameterizations in global climate models. This study describes the development of an ensemble variationally constrained objective analysis of atmospheric large-scale forcing data and its application to evaluate the cloud biases in the Community Atmospheric Model (CAM5). Sensitivities of the variational objective analysis to background data, error covariance matrix and constraint variables are described and used to quantify the uncertainties in the large-scale forcing data. Application of the ensemblemore » forcing in the CAM5 SCM during March 2000 intensive operational period (IOP) at the Southern Great Plains (SGP) of the Atmospheric Radiation Measurement (ARM) program shows systematic biases in the model simulations that cannot be explained by the uncertainty of large-scale forcing data, which points to the deficiencies of physical parameterizations. The SCM is shown to overestimate high clouds and underestimate low clouds. These biases are found to also exist in the global simulation of CAM5 when it is compared with satellite data.« less

An ensemble constrained variational analysis of atmospheric forcing data and its application to evaluate clouds in CAM5: Ensemble 3DCVA and Its Application

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tang, Shuaiqi; Zhang, Minghua; Xie, Shaocheng

Large-scale atmospheric forcing data can greatly impact the simulations of atmospheric process models including Large Eddy Simulations (LES), Cloud Resolving Models (CRMs) and Single-Column Models (SCMs), and impact the development of physical parameterizations in global climate models. This study describes the development of an ensemble variationally constrained objective analysis of atmospheric large-scale forcing data and its application to evaluate the cloud biases in the Community Atmospheric Model (CAM5). Sensitivities of the variational objective analysis to background data, error covariance matrix and constraint variables are described and used to quantify the uncertainties in the large-scale forcing data. Application of the ensemblemore » forcing in the CAM5 SCM during March 2000 intensive operational period (IOP) at the Southern Great Plains (SGP) of the Atmospheric Radiation Measurement (ARM) program shows systematic biases in the model simulations that cannot be explained by the uncertainty of large-scale forcing data, which points to the deficiencies of physical parameterizations. The SCM is shown to overestimate high clouds and underestimate low clouds. These biases are found to also exist in the global simulation of CAM5 when it is compared with satellite data.« less

Astronomy in the region between 1 mm and 0.1 mm wavelength

NASA Technical Reports Server (NTRS)

Weiss, Rainer; Meyer, Stephan S.

1994-01-01

The research under this grant resulted in the measurement of anisotropy of the Cosmic Microwave Background Radiation (CMBR) on angular scales from 90 degrees to 0.3 degrees. A bolometric radiometer was built with a sensitivity of better than 500 micro K divided by the square root of (Hz). The measurements complement the COBE anisotropy measurement in two ways. The large scale measurements were shown to cross-correlate with the COBE DMR anisotropy detection, confirming the results. The small scale measurements further the understanding of the structure in the CMBR on scales where we can begin to model the early stages in galaxy and galaxy cluster formation.

Revealing infinite derivative gravity's true potential: The weak-field limit around de Sitter backgrounds

NASA Astrophysics Data System (ADS)

Edholm, James

2018-03-01

General Relativity is known to produce singularities in the potential generated by a point source. Our universe can be modeled as a de Sitter (dS) metric and we show that ghost-free infinite derivative gravity (IDG) produces a nonsingular potential around a dS background, while returning to the GR prediction at large distances. We also show that although there are an apparently infinite number of coefficients in the theory, only a finite number actually affect the predictions. By writing the linearized equations of motion in a simplified form, we find that at distances below the Hubble length scale, the difference between the IDG potential around a flat background and around a de Sitter background is negligible.

Large-Scale Coronal Heating from "Cool" Activity in the Solar Magnetic Network

NASA Technical Reports Server (NTRS)

Falconer, D. A.; Moore, R. L.; Porter, J. G.; Hathaway, D. H.

1999-01-01

In Fe XII images from SOHO/EIT, the quiet solar corona shows structure on scales ranging from sub-supergranular (i.e., bright points and coronal network) to multi-supergranular (large-scale corona). In Falconer et al 1998 (Ap.J., 501, 386) we suppressed the large-scale background and found that the network-scale features are predominantly rooted in the magnetic network lanes at the boundaries of the supergranules. Taken together, the coronal network emission and bright point emission are only about 5% of the entire quiet solar coronal Fe XII emission. Here we investigate the relationship between the large-scale corona and the network as seen in three different EIT filters (He II, Fe IX-X, and Fe XII). Using the median-brightness contour, we divide the large-scale Fe XII corona into dim and bright halves, and find that the bright-half/dim half brightness ratio is about 1.5. We also find that the bright half relative to the dim half has 10 times greater total bright point Fe XII emission, 3 times greater Fe XII network emission, 2 times greater Fe IX-X network emission, 1.3 times greater He II network emission, and has 1.5 times more magnetic flux. Also, the cooler network (He II) radiates an order of magnitude more energy than the hotter coronal network (Fe IX-X, and Fe XII). From these results we infer that: 1) The heating of the network and the heating of the large-scale corona each increase roughly linearly with the underlying magnetic flux. 2) The production of network coronal bright points and heating of the coronal network each increase nonlinearly with the magnetic flux. 3) The heating of the large-scale corona is driven by widespread cooler network activity rather than by the exceptional network activity that produces the network coronal bright points and the coronal network. 4) The large-scale corona is heated by a nonthermal process since the driver of its heating is cooler than it is. This work was funded by the Solar Physics Branch of NASA's office of Space Science through the SR&T Program and the SEC Guest Investigator Program.

Cosmology with CLASS

NASA Astrophysics Data System (ADS)

Watts, Duncan; CLASS Collaboration

2018-01-01

The Cosmology Large Angular Scale Surveyor (CLASS) will use large-scale measurements of the polarized cosmic microwave background (CMB) to constrain the physics of inflation, reionization, and massive neutrinos. The experiment is designed to characterize the largest scales, which are inaccessible to most ground-based experiments, and remove Galactic foregrounds from the CMB maps. In this dissertation talk, I present simulations of CLASS data and demonstrate their ability to constrain the simplest single-field models of inflation and to reduce the uncertainty of the optical depth to reionization, τ, to near the cosmic variance limit, significantly improving on current constraints. These constraints will bring a qualitative shift in our understanding of standard ΛCDM cosmology. In particular, CLASS's measurement of τ breaks cosmological parameter degeneracies. Probes of large scale structure (LSS) test the effect of neutrino free-streaming at small scales, which depends on the mass of the neutrinos. CLASS's τ measurement, when combined with next-generation LSS and BAO measurements, will enable a 4σ detection of neutrino mass, compared with 2σ without CLASS data.. I will also briefly discuss the CLASS experiment's measurements of circular polarization of the CMB and the implications of the first-such near-all-sky map.

Search for large extra dimensions in dielectron and diphoton production.

PubMed

Abbott, B; Abolins, M; Abramov, V; Acharya, B S; Adams, D L; Adams, M; Alves, G A; Amos, N; Anderson, E W; Baarmand, M M; Babintsev, V V; Babukhadia, L; Baden, A; Baldin, B; Balm, P W; Banerjee, S; Bantly, J; Barberis, E; Baringer, P; Bartlett, J F; Bassler, U; Bean, A; Begel, M; Belyaev, A; Beri, S B; Bernardi, G; Bertram, I; Besson, A; Bezzubov, V A; Bhat, P C; Bhatnagar, V; Bhattacharjee, M; Blazey, G; Blessing, S; Boehnlein, A; Bojko, N I; Borcherding, F; Brandt, A; Breedon, R; Briskin, G; Brock, R; Brooijmans, G; Bross, A; Buchholz, D; Buehler, M; Buescher, V; Burtovoi, V S; Butler, J M; Canelli, F; Carvalho, W; Casey, D; Casilum, Z; Castilla-Valdez, H; Chakraborty, D; Chan, K M; Chekulaev, S V; Cho, D K; Choi, S; Chopra, S; Christenson, J H; Chung, M; Claes, D; Clark, A R; Cochran, J; Coney, L; Connolly, B; Cooper, W E; Coppage, D; Cummings, M A; Cutts, D; Dahl, O I; Davis, G A; Davis, K; De, K; Del Signore, K; Demarteau, M; Demina, R; Demine, P; Denisov, D; Denisov, S P; Desai, S; Diehl, H T; Diesburg, M; Di Loreto, G; Doulas, S; Draper, P; Ducros, Y; Dudko, L V; Duensing, S; Dugad, S R; Dyshkant, A; Edmunds, D; Ellison, J; Elvira, V D; Engelmann, R; Eno, S; Eppley, G; Ermolov, P; Eroshin, O V; Estrada, J; Evans, H; Evdokimov, V N; Fahland, T; Feher, S; Fein, D; Ferbel, T; Fisk, H E; Fisyak, Y; Flattum, E; Fleuret, F; Fortner, M; Frame, K C; Fuess, S; Gallas, E; Galyaev, A N; Gartung, P; Gavrilov, V; Genik, R J; Genser, K; Gerber, C E; Gershtein, Y; Gibbard, B; Gilmartin, R; Ginther, G; Gómez, B; Gómez, G; Goncharov, P I; González Solís, J L; Gordon, H; Goss, L T; Gounder, K; Goussiou, A; Graf, N; Graham, G; Grannis, P D; Green, J A; Greenlee, H; Grinstein, S; Groer, L; Grudberg, P; Grünendahl, S; Gupta, A; Gurzhiev, S N; Gutierrez, G; Gutierrez, P; Hadley, N J; Haggerty, H; Hagopian, S; Hagopian, V; Hahn, K S; Hall, R E; Hanlet, P; Hansen, S; Hauptman, J M; Hays, C; Hebert, C; Hedin, D; Heinson, A P; Heintz, U; Heuring, T; Hirosky, R; Hobbs, J D; Hoeneisen, B; Hoftun, J S; Hou, S; Huang, Y; Ito, A S; Jerger, S A; Jesik, R; Johns, K; Johnson, M; Jonckheere, A; Jones, M; Jöstlein, H; Juste, A; Kahn, S; Kajfasz, E; Karmanov, D; Karmgard, D; Kehoe, R; Kim, S K; Klima, B; Klopfenstein, C; Knuteson, B; Ko, W; Kohli, J M; Kostritskiy, A V; Kotcher, J; Kotwal, A V; Kozelov, A V; Kozlovsky, E A; Krane, J; Krishnaswamy, M R; Krzywdzinski, S; Kubantsev, M; Kuleshov, S; Kulik, Y; Kunori, S; Kuznetsov, V E; Landsberg, G; Leflat, A; Lehner, F; Li, J; Li, Q Z; Lima, J G; Lincoln, D; Linn, S L; Linnemann, J; Lipton, R; Lucotte, A; Lueking, L; Lundstedt, C; Maciel, A K; Madaras, R J; Manankov, V; Mao, H S; Marshall, T; Martin, M I; Martin, R D; Mauritz, K M; May, B; Mayorov, A A; McCarthy, R; McDonald, J; McMahon, T; Melanson, H L; Meng, X C; Merkin, M; Merritt, K W; Miao, C; Miettinen, H; Mihalcea, D; Mincer, A; Mishra, C S; Mokhov, N; Mondal, N K; Montgomery, H E; Moore, R W; Mostafa, M; da Motta, H; Nagy, E; Nang, F; Narain, M; Narasimham, V S; Neal, H A; Negret, J P; Negroni, S; Norman, D; Oesch, L; Oguri, V; Olivier, B; Oshima, N; Padley, P; Pan, L J; Para, A; Parashar, N; Partridge, R; Parua, N; Paterno, M; Patwa, A; Pawlik, B; Perkins, J; Peters, M; Peters, O; Piegaia, R; Piekarz, H; Pope, B G; Popkov, E; Prosper, H B; Protopopescu, S; Qian, J; Quintas, P Z; Raja, R; Rajagopalan, S; Ramberg, E; Rapidis, P A; Reay, N W; Reucroft, S; Rha, J; Rijssenbeek, M; Rockwell, T; Roco, M; Rubinov, P; Ruchti, R; Rutherfoord, J; Santoro, A; Sawyer, L; Schamberger, R D; Schellman, H; Schwartzman, A; Sculli, J; Sen, N; Shabalina, E; Shankar, H C; Shivpuri, R K; Shpakov, D; Shupe, M; Sidwell, R A; Simak, V; Singh, H; Singh, J B; Sirotenko, V; Slattery, P; Smith, E; Smith, R P; Snihur, R; Snow, G R; Snow, J; Snyder, S; Solomon, J; Sorín, V; Sosebee, M; Sotnikova, N; Soustruznik, K; Souza, M; Stanton, N R; Steinbrück, G; Stephens, R W; Stevenson, M L; Stichelbaut, F; Stoker, D; Stolin, V; Stoyanova, D A; Strauss, M; Streets, K; Strovink, M; Stutte, L; Sznajder, A; Taylor, W; Tentindo-Repond, S; Thompson, J; Toback, D; Tripathi, S M; Trippe, T G; Turcot, A S; Tuts, P M; van Gemmeren, P; Vaniev, V; Van Kooten, R; Varelas, N; Volkov, A A; Vorobiev, A P; Wahl, H D; Wang, H; Wang, Z; Warchol, J; Watts, G; Wayne, M; Weerts, H; White, A; White, J T; Whiteson, D; Wightman, J A; Wijngaarden, D A; Willis, S; Wimpenny, S J; Wirjawan, J V; Womersley, J; Wood, D R; Yamada, R; Yamin, P; Yasuda, T; Yip, K; Youssef, S; Yu, J; Yu, Z; Zanabria, M; Zheng, H; Zhou, Z; Zhu, Z H; Zielinski, M; Zieminska, D; Zieminski, A; Zutshi, V; Zverev, E G; Zylberstejn, A

2001-02-12

We report a search for effects of large extra spatial dimensions in pp collisions at a center-of-mass energy of 1.8 TeV with the D0 detector, using events containing a pair of electrons or photons. The data are in good agreement with the expected background and do not exhibit evidence for large extra dimensions. We set the most restrictive lower limits to date, at the 95% C.L. on the effective Planck scale between 1.0 and 1.4 TeV for several formalisms and numbers of extra dimensions.

Hybrid Magnetic Shielding

NASA Astrophysics Data System (ADS)

Royal, Kevin; Crawford, Christopher; Mullins, Andrew; Porter, Greg; Blanton, Hunter; Johnstone, Connor; Kistler, Ben; Olivera, Daniela

2017-09-01

The search for the electric dipole moment of the neutron requires the ambient magnetic field to be on the pT scale which is accomplished with large magnetic shielding rooms. These rooms are fitted with large mu-metal sheets to allow for passive cancellation of background magnetic fields. Active shielding technology cannot uniformly cancel background magnetic fields. These issues can be remedied by combining the methods into a hybrid system. The design used is composed of panels that have an active layer of cancellation between two sheets of mu-metal. The panels form a cube and draw in magnetic fields perpendicular to the surface which can then be reduced using active shielding. This work is supported by the Department of Energy under Contract DE-SC0008107.

Statistical mechanics of soft-boson phase transitions

NASA Technical Reports Server (NTRS)

Gupta, Arun K.; Hill, Christopher T.; Holman, Richard; Kolb, Edward W.

1991-01-01

The existence of structure on large (100 Mpc) scales, and limits to anisotropies in the cosmic microwave background radiation (CMBR), have imperiled models of structure formation based solely upon the standard cold dark matter scenario. Novel scenarios, which may be compatible with large scale structure and small CMBR anisotropies, invoke nonlinear fluctuations in the density appearing after recombination, accomplished via the use of late time phase transitions involving ultralow mass scalar bosons. Herein, the statistical mechanics are studied of such phase transitions in several models involving naturally ultralow mass pseudo-Nambu-Goldstone bosons (pNGB's). These models can exhibit several interesting effects at high temperature, which is believed to be the most general possibilities for pNGB's.

Fundamental tests of galaxy formation theory

NASA Technical Reports Server (NTRS)

Silk, J.

1982-01-01

The structure of the universe as an environment where traces exist of the seed fluctuations from which galaxies formed is studied. The evolution of the density fluctuation modes that led to the eventual formation of matter inhomogeneities is reviewed, How the resulting clumps developed into galaxies and galaxy clusters acquiring characteristic masses, velocity dispersions, and metallicities, is discussed. Tests are described that utilize the large scale structure of the universe, including the dynamics of the local supercluster, the large scale matter distribution, and the anisotropy of the cosmic background radiation, to probe the earliest accessible stages of evolution. Finally, the role of particle physics is described with regard to its observable implications for galaxy formation.

Algorithm of OMA for large-scale orthology inference

PubMed Central

Roth, Alexander CJ; Gonnet, Gaston H; Dessimoz, Christophe

2008-01-01

Background OMA is a project that aims to identify orthologs within publicly available, complete genomes. With 657 genomes analyzed to date, OMA is one of the largest projects of its kind. Results The algorithm of OMA improves upon standard bidirectional best-hit approach in several respects: it uses evolutionary distances instead of scores, considers distance inference uncertainty, includes many-to-many orthologous relations, and accounts for differential gene losses. Herein, we describe in detail the algorithm for inference of orthology and provide the rationale for parameter selection through multiple tests. Conclusion OMA contains several novel improvement ideas for orthology inference and provides a unique dataset of large-scale orthology assignments. PMID:19055798

Large-scale 3D inversion of marine controlled source electromagnetic data using the integral equation method

NASA Astrophysics Data System (ADS)

Zhdanov, M. S.; Cuma, M.; Black, N.; Wilson, G. A.

2009-12-01

The marine controlled source electromagnetic (MCSEM) method has become widely used in offshore oil and gas exploration. Interpretation of MCSEM data is still a very challenging problem, especially if one would like to take into account the realistic 3D structure of the subsurface. The inversion of MCSEM data is complicated by the fact that the EM response of a hydrocarbon-bearing reservoir is very weak in comparison with the background EM fields generated by an electric dipole transmitter in complex geoelectrical structures formed by a conductive sea-water layer and the terranes beneath it. In this paper, we present a review of the recent developments in the area of large-scale 3D EM forward modeling and inversion. Our approach is based on using a new integral form of Maxwell’s equations allowing for an inhomogeneous background conductivity, which results in a numerically effective integral representation for 3D EM field. This representation provides an efficient tool for the solution of 3D EM inverse problems. To obtain a robust inverse model of the conductivity distribution, we apply regularization based on a focusing stabilizing functional which allows for the recovery of models with both smooth and sharp geoelectrical boundaries. The method is implemented in a fully parallel computer code, which makes it possible to run large-scale 3D inversions on grids with millions of inversion cells. This new technique can be effectively used for active EM detection and monitoring of the subsurface targets.

Large-scale fluctuations in the cosmic ionizing background: the impact of beamed source emission

NASA Astrophysics Data System (ADS)

Suarez, Teresita; Pontzen, Andrew

2017-12-01

When modelling the ionization of gas in the intergalactic medium after reionization, it is standard practice to assume a uniform radiation background. This assumption is not always appropriate; models with radiative transfer show that large-scale ionization rate fluctuations can have an observable impact on statistics of the Lyman α forest. We extend such calculations to include beaming of sources, which has previously been neglected but which is expected to be important if quasars dominate the ionizing photon budget. Beaming has two effects: first, the physical number density of ionizing sources is enhanced relative to that directly observed; and secondly, the radiative transfer itself is altered. We calculate both effects in a hard-edged beaming model where each source has a random orientation, using an equilibrium Boltzmann hierarchy in terms of spherical harmonics. By studying the statistical properties of the resulting ionization rate and H I density fields at redshift z ∼ 2.3, we find that the two effects partially cancel each other; combined, they constitute a maximum 5 per cent correction to the power spectrum P_{H I}(k) at k = 0.04 h Mpc-1. On very large scales (k < 0.01 h Mpc-1) the source density renormalization dominates; it can reduce, by an order of magnitude, the contribution of ionizing shot noise to the intergalactic H I power spectrum. The effects of beaming should be considered when interpreting future observational data sets.

Emergence of Multiscaling in a Random-Force Stirred Fluid

NASA Astrophysics Data System (ADS)

Yakhot, Victor; Donzis, Diego

2017-07-01

We consider the transition to strong turbulence in an infinite fluid stirred by a Gaussian random force. The transition is defined as a first appearance of anomalous scaling of normalized moments of velocity derivatives (dissipation rates) emerging from the low-Reynolds-number Gaussian background. It is shown that, due to multiscaling, strongly intermittent rare events can be quantitatively described in terms of an infinite number of different "Reynolds numbers" reflecting a multitude of anomalous scaling exponents. The theoretically predicted transition disappears at Rλ≤3 . The developed theory is in quantitative agreement with the outcome of large-scale numerical simulations.

A 3D model of polarized dust emission in the Milky Way

NASA Astrophysics Data System (ADS)

Martínez-Solaeche, Ginés; Karakci, Ata; Delabrouille, Jacques

2018-05-01

We present a three-dimensional model of polarized galactic dust emission that takes into account the variation of the dust density, spectral index and temperature along the line of sight, and contains randomly generated small-scale polarization fluctuations. The model is constrained to match observed dust emission on large scales, and match on smaller scales extrapolations of observed intensity and polarization power spectra. This model can be used to investigate the impact of plausible complexity of the polarized dust foreground emission on the analysis and interpretation of future cosmic microwave background polarization observations.

The Explorer of Diffuse Galactic Emission (EDGE): Determining the Large-Scale Structure Evolution in the Universe

NASA Technical Reports Server (NTRS)

Silverberg, R. F.; Cheng, E. S.; Cottingham, D. A.; Fixsen, D. J.; Meyer, S. S.; Knox, L.; Timbie, P.; Wilson, G.

2003-01-01

Measurements of the large-scale anisotropy of the Cosmic Infared Background (CIB) can be used to determine the characteristics of the distribution of galaxies at the largest spatial scales. With this information important tests of galaxy evolution models and primordial structure growth are possible. In this paper, we describe the scientific goals, instrumentation, and operation of EDGE, a mission using an Antarctic Long Duration Balloon (LDB) platform. EDGE will osbserve the anisotropy in the CIB in 8 spectral bands from 270 GHz-1.5 THz with 6 arcminute angular resolution over a region -400 square degrees. EDGE uses a one-meter class off-axis telescope and an array of Frequency Selective Bololeters (FSB) to provide the compact and efficient multi-colar, high sensitivity radiometer required to achieve its scientific objectives.

Navy Virginia (SSN-774) Class Attack Submarine Procurement: Background and Issues for Congress

DTIC Science & Technology

2016-02-12

Tomahawk cruise missiles or other payloads, such as large-diameter unmanned underwater vehicles (UUVs). The Navy’s FY2016 30-year SSN procurement plan, if...again on a smaller scale than possible with the SSGNs);  covert offensive and defensive mine warfare;  anti-submarine warfare (ASW); and  anti...Tomahawk cruise missiles or other payloads, such as large-diameter unmanned underwater vehicles (UUVs). 17 The four additional launch tubes in the

The Contribution of z < or Approx. 6 Sources to the Spatial Coherence in the Unresolved Cosmic Near-Infrared and X-Ray Backgrounds

NASA Technical Reports Server (NTRS)

Helgason, K.; Cappelluti, N.; Hasinger, G.; Kashlinsky, A.; Ricotti, M.

2014-01-01

A spatial clustering signal has been established in Spitzer/IRAC measurements of the unresolved cosmic near-infrared background (CIB) out to large angular scales, approx. 1deg. This CIB signal, while significantly exceeding the contribution from the remaining known galaxies, was further found to be coherent at a highly statistically significant level with the unresolved soft cosmic X-ray background (CXB). This measurement probes the unresolved CXB to very faint source levels using deep near-IR source subtraction.We study contributions from extragalactic populations at low to intermediate redshifts to the measured positive cross-power signal of the CIB fluctuations with the CXB. We model the X-ray emission from active galactic nuclei (AGNs), normal galaxies, and hot gas residing in virialized structures, calculating their CXB contribution including their spatial coherence with all infrared emitting counterparts. We use a halo model framework to calculate the auto and cross-power spectra of the unresolved fluctuations based on the latest constraints of the halo occupation distribution and the biasing of AGNs, galaxies, and diffuse emission. At small angular scales (1), the 4.5microns versus 0.5-2 keV coherence can be explained by shot noise from galaxies and AGNs. However, at large angular scales (approx.10), we find that the net contribution from the modeled populations is only able to account for approx. 3% of the measured CIB×CXB cross-power. The discrepancy suggests that the CIB×CXB signal originates from the same unknown source population producing the CIB clustering signal out to approx. 1deg.

CALDER: Cryogenic light detectors for background-free searches

NASA Astrophysics Data System (ADS)

Di Domizio, S.; Bellini, F.; Cardani, L.; Casali, N.; Castellano, M. G.; Colantoni, I.; Cosmelli, C.; Cruciani, A.; D'Addabbo, A.; Martinez, M.; Minutolo, L.; Tomei, C.; Vignati, M.

2018-01-01

CALDER is a R&D project for the development of cryogenic light detectors with an active surface of 5x5cm2 and an energy resolution of 20 eV RMS for visible and UV photons. These devices can enhance the sensitivity of next generation large mass bolometric detectors for rare event searches, providing an active background rejection method based on particle discrimination. A CALDER detector is composed by a large area Si absorber substrate with superconducting kinetic inductance detectors (KIDs) deposited on it. The substrate converts the incoming light into athermal phonons, that are then sensed by the KIDs. KID technology combine fabrication simplicity with natural attitude to frequency-domain multiplexing, making it an ideal candidate for a large scale bolometric experiments. We will give an overview of the CALDER project and show the performances obtained with prototype detectors both in terms of energy resolution and efficiency.

Primordial black hole production in Critical Higgs Inflation

NASA Astrophysics Data System (ADS)

Ezquiaga, Jose María; García-Bellido, Juan; Ruiz Morales, Ester

2018-01-01

Primordial Black Holes (PBH) arise naturally from high peaks in the curvature power spectrum of near-inflection-point single-field inflation, and could constitute today the dominant component of the dark matter in the universe. In this letter we explore the possibility that a broad spectrum of PBH is formed in models of Critical Higgs Inflation (CHI), where the near-inflection point is related to the critical value of the RGE running of both the Higgs self-coupling λ (μ) and its non-minimal coupling to gravity ξ (μ). We show that, for a wide range of model parameters, a half-domed-shaped peak in the matter spectrum arises at sufficiently small scales that it passes all the constraints from large scale structure observations. The predicted cosmic microwave background spectrum at large scales is in agreement with Planck 2015 data, and has a relatively large tensor-to-scalar ratio that may soon be detected by B-mode polarization experiments. Moreover, the wide peak in the power spectrum gives an approximately lognormal PBH distribution in the range of masses 0.01- 100M⊙, which could explain the LIGO merger events, while passing all present PBH observational constraints. The stochastic background of gravitational waves coming from the unresolved black-hole-binary mergers could also be detected by LISA or PTA. Furthermore, the parameters of the CHI model are consistent, within 2σ, with the measured Higgs parameters at the LHC and their running. Future measurements of the PBH mass spectrum could allow us to obtain complementary information about the Higgs couplings at energies well above the EW scale, and thus constrain new physics beyond the Standard Model.

New Empirical Evidence on the Effect of Educational Tracking on Social Inequalities in Reading Achievement

ERIC Educational Resources Information Center

Lavrijsen, Jeroen; Nicaise, Ides

2015-01-01

One of the major imperatives behind the comprehensivisation of secondary education was the belief that postponing the age at which students are tracked in different educational routes would mitigate the effect of social background on educational outcomes. Comparative investigations of large-scale international student achievement tests in…

Reframing the Conversation: Insights from the Oral Histories of Three 1990 TFA Participants

ERIC Educational Resources Information Center

Rogers, Bethany; Blumenreich, Megan

2013-01-01

Background/Context: Researchers have examined the challenges of staffing urban, under served classrooms primarily through large-scale data sets; policymakers have responded with strategies intended to recruit more or "better" teachers into the classroom through programs such as the popular Teach for America. Yet there is little…

Large-Scale Campus Computer Technology Implementation: Lessons from the First Year.

ERIC Educational Resources Information Center

Nichols, Todd; Frazer, Linda H.

The purpose of the Elementary Technology Demonstration Schools (ETDS) Project, funded by IBM and Apple, Inc., was to demonstrate the effectiveness of technology in accelerating the learning of low achieving at-risk students and enhancing the education of high achieving students. The paper begins by giving background information on the district,…

Investigating Sexual Abuse: Findings of a 15-Year Longitudinal Study

ERIC Educational Resources Information Center

McCormack, Bob; Kavanagh, Denise; Caffrey, Shay; Power, Anne

2005-01-01

Background: There is a lack of longitudinal large-scale studies of sexual abuse in intellectual disability services. Such studies offer opportunities to examine patterns in disclosure, investigation and outcomes, and to report on incidence and trends. Methods: All allegations of sexual abuse (n = 250) involving service users as victims or…

Impact of Large-Scale Assessment on Mexico's Education Policies

ERIC Educational Resources Information Center

Martínez-Rizo, Felipe; Silva-Guerrero, Juana E.

2016-01-01

After an introduction that briefly describes the two studies on which this article is based, we provide background information on Mexico's education system and the sociopolitical context of the country, and we explain relevant issues of this context for education, arising from the transition from an authoritarian to a democratic political system,…

Constructivism as a Framework for Literacy Teacher Education Courses: The Cases of Six Literacy Teacher Educators

ERIC Educational Resources Information Center

Kosnik, Clare; Menna, Lydia; Dharamshi, Pooja; Beck, Clive

2018-01-01

This paper presents findings from the large-scale study "Literacy Teacher Educators: Their Backgrounds, Visions, and Practices" that includes 28 literacy/English teacher educators (LTEs) from four countries. The participants were interviewed three times and shared their course outlines. Six pre-service LTEs who use a constructivist…

Pre- and Postnatal Influences on Preschool Mental Health: A Large-Scale Cohort Study

ERIC Educational Resources Information Center

Robinson, Monique; Oddy, Wendy H.; Li, Jianghong; Kendall, Garth E.; de Klerk, Nicholas H.; Silburn, Sven R.; Zubrick, Stephen R.; Newnham, John P.; Stanley, Fiona J.; Mattes, Eugen

2008-01-01

Background: Methodological challenges such as confounding have made the study of the early determinants of mental health morbidity problematic. This study aims to address these challenges in investigating antenatal, perinatal and postnatal risk factors for the development of mental health problems in pre-school children in a cohort of Western…

The Air Force Advanced Instructional System (AIS): An Overview.

ERIC Educational Resources Information Center

Yasutake, Joseph Y.; Stobie, William H.

The Air Force Advanced Instructional System (AIS) is a prototype computer-based multimedia system for the administration and management of individualized technical training on a large scale. The paper provides an overview of the AIS: (1) its purposes and goals, (2) the background and rationale for the development approach, (3) a basic description…

Competencies in Geriatric Nursing: Empirical Evidence from a Computer-Based Large-Scale Assessment Calibration Study

ERIC Educational Resources Information Center

Kaspar, Roman; Döring, Ottmar; Wittmann, Eveline; Hartig, Johannes; Weyland, Ulrike; Nauerth, Annette; Möllers, Michaela; Rechenbach, Simone; Simon, Julia; Worofka, Iberé

2016-01-01

Valid and reliable standardized assessment of nursing competencies is needed to monitor the quality of vocational education and training (VET) in nursing and evaluate learning outcomes for care work trainees with increasingly heterogeneous learning backgrounds. To date, however, the modeling of professional competencies has not yet evolved into…

Student Background Factors Influencing Student Achievement in Serbia

ERIC Educational Resources Information Center

Teodorovic, Jelena

2012-01-01

This paper describes student-level findings of the first large-scale comprehensive school effectiveness study of the primary education in Serbia. Twenty-five student-level variables were examined in a three-level HLM model using a study sample of almost 5000 students, over 250 classrooms and over 100 schools. Differences between the students were…

DOE Office of Scientific and Technical Information (OSTI.GOV)

Doux, Cyrille; Schaan, Emmanuel; Aubourg, Eric

We present the first detection of a correlation between the Lyman-α forest and cosmic microwave background gravitational lensing. For each Lyman-α forest in SDSS-III/BOSS DR12, we correlate the one-dimensional power spectrum with the cosmic microwave background lensing convergence on the same line of sight from Planck. This measurement constitutes a position-dependent power spectrum, or a squeezed bispectrum, and quantifies the nonlinear response of the Lyman-α forest power spectrum to a large-scale overdensity. The signal is measured at 5σ and is consistent with the expectation of the standard ΛCDM cosmological model. We measure the linear bias of the Lyman-α forest withmore » respect to the dark matter distribution and constrain a combination of nonlinear terms including the nonlinear bias. This new observable provides a consistency check for the Lyman-α forest as a large-scale structure probe and tests our understanding of the relation between intergalactic gas and dark matter. In the future, it could be used to test hydrodynamical simulations and calibrate the relation between the Lyman-α forest and dark matter.« less

The isotropic radio background revisited

NASA Astrophysics Data System (ADS)

Fornengo, Nicolao; Lineros, Roberto A.; Regis, Marco; Taoso, Marco

2014-04-01

We present an extensive analysis on the determination of the isotropic radio background. We consider six different radio maps, ranging from 22 MHz to 2.3 GHz and covering a large fraction of the sky. The large scale emission is modeled as a linear combination of an isotropic component plus the Galactic synchrotron radiation and thermal bremsstrahlung. Point-like and extended sources are either masked or accounted for by means of a template. We find a robust estimate of the isotropic radio background, with limited scatter among different Galactic models. The level of the isotropic background lies significantly above the contribution obtained by integrating the number counts of observed extragalactic sources. Since the isotropic component dominates at high latitudes, thus making the profile of the total emission flat, a Galactic origin for such excess appears unlikely. We conclude that, unless a systematic offset is present in the maps, and provided that our current understanding of the Galactic synchrotron emission is reasonable, extragalactic sources well below the current experimental threshold seem to account for the majority of the brightness of the extragalactic radio sky.

Background-Oriented Schlieren for Large-Scale and High-Speed Aerodynamic Phenomena

NASA Technical Reports Server (NTRS)

Mizukaki, Toshiharu; Borg, Stephen; Danehy, Paul M.; Murman, Scott M.; Matsumura, Tomoharu; Wakabayashi, Kunihiko; Nakayama, Yoshio

2015-01-01

Visualization of the flow field around a generic re-entry capsule in subsonic flow and shock wave visualization with cylindrical explosives have been conducted to demonstrate sensitivity and applicability of background-oriented schlieren (BOS) for field experiments. The wind tunnel experiment suggests that BOS with a fine-pixel imaging device has a density change detection sensitivity on the order of 10(sup -5) in subsonic flow. In a laboratory setup, the structure of the shock waves generated by explosives have been successfully reconstructed by a computed tomography method combined with BOS.

Cosmological cosmic strings

NASA Technical Reports Server (NTRS)

Gregory, Ruth

1988-01-01

The effect of an infinite cosmic string on a cosmological background is investigated. It is found that the metric is approximately a scaled version of the empty space string metric, i.e., conical in nature. Results are used to place bounds on the amount of cylindrical gravitational radiation currently emitted by such a string. The gravitational radiation equations are then analyzed explicitly and it is shown that even initially large disturbances are rapidly damped as the expansion proceeds. The implications of the gravitational radiation background and the limitations of the quadrupole formula are discussed.

Enhancing the Spectral Hardening of Cosmic TeV Photons by Mixing with Axionlike Particles in the Magnetized Cosmic Web.

PubMed

Montanino, Daniele; Vazza, Franco; Mirizzi, Alessandro; Viel, Matteo

2017-09-08

Large-scale extragalactic magnetic fields may induce conversions between very-high-energy photons and axionlike particles (ALPs), thereby shielding the photons from absorption on the extragalactic background light. However, in simplified "cell" models, used so far to represent extragalactic magnetic fields, this mechanism would be strongly suppressed by current astrophysical bounds. Here we consider a recent model of extragalactic magnetic fields obtained from large-scale cosmological simulations. Such simulated magnetic fields would have large enhancement in the filaments of matter. As a result, photon-ALP conversions would produce a significant spectral hardening for cosmic TeV photons. This effect would be probed with the upcoming Cherenkov Telescope Array detector. This possible detection would give a unique chance to perform a tomography of the magnetized cosmic web with ALPs.

Conditional sampling technique to test the applicability of the Taylor hypothesis for the large-scale coherent structures

NASA Technical Reports Server (NTRS)

Hussain, A. K. M. F.

1980-01-01

Comparisons of the distributions of large scale structures in turbulent flow with distributions based on time dependent signals from stationary probes and the Taylor hypothesis are presented. The study investigated an area in the near field of a 7.62 cm circular air jet at a Re of 32,000, specifically having coherent structures through small-amplitude controlled excitation and stable vortex pairing in the jet column mode. Hot-wire and X-wire anemometry were employed to establish phase averaged spatial distributions of longitudinal and lateral velocities, coherent Reynolds stress and vorticity, background turbulent intensities, streamlines and pseudo-stream functions. The Taylor hypothesis was used to calculate spatial distributions of the phase-averaged properties, with results indicating that the usage of the local time-average velocity or streamwise velocity produces large distortions.

The Hantzsche-Wendt manifold in cosmic topology

NASA Astrophysics Data System (ADS)

Aurich, R.; Lustig, S.

2014-08-01

The Hantzsche-Wendt space is one of the 17 multiply connected spaces of the three-dimensional Euclidean space {{{E}}^{3}}. It is a compact and orientable manifold which can serve as a model for a spatial finite universe. Since it possesses much fewer matched back-to-back circle pairs on the cosmic microwave background (CMB) sky than the other compact flat spaces, it can escape the detection by a search for matched circle pairs. The suppression of temperature correlations C(\\vartheta ) on large angular scales on the CMB sky is studied. It is shown that the large-scale correlations are of the same order as for the three-torus topology but express a much larger variability. The Hantzsche-Wendt manifold provides a topological possibility with reduced large-angle correlations that can hide from searches for matched back-to-back circle pairs.

Cosmic microwave background anisotropies in cold dark matter models with cosmological constant: The intermediate versus large angular scales

NASA Technical Reports Server (NTRS)

Stompor, Radoslaw; Gorski, Krzysztof M.

1994-01-01

We obtain predictions for cosmic microwave background anisotropies at angular scales near 1 deg in the context of cold dark matter models with a nonzero cosmological constant, normalized to the Cosmic Background Explorer (COBE) Differential Microwave Radiometer (DMR) detection. The results are compared to those computed in the matter-dominated models. We show that the coherence length of the Cosmic Microwave Background (CMB) anisotropy is almost insensitive to cosmological parameters, and the rms amplitude of the anisotropy increases moderately with decreasing total matter density, while being most sensitive to the baryon abundance. We apply these results in the statistical analysis of the published data from the UCSB South Pole (SP) experiment (Gaier et al. 1992; Schuster et al. 1993). We reject most of the Cold Dark Matter (CDM)-Lambda models at the 95% confidence level when both SP scans are simulated together (although the combined data set renders less stringent limits than the Gaier et al. data alone). However, the Schuster et al. data considered alone as well as the results of some other recent experiments (MAX, MSAM, Saskatoon), suggest that typical temperature fluctuations on degree scales may be larger than is indicated by the Gaier et al. scan. If so, CDM-Lambda models may indeed provide, from a point of view of CMB anisotropies, an acceptable alternative to flat CDM models.

Fermi rules out the IC/CMB model for the Large-Scale Jet X-ray emission of 3C 273

NASA Astrophysics Data System (ADS)

Georganopoulos, Markos; Meyer, E. T.

2014-01-01

The process responsible for the Chandra-detected X-ray emission from the large-scale jets of powerful quasars is not clear yet. The two main models are inverse Compton scattering off the cosmic microwave background (IC/CMB) photons and synchrotron emission from a population of electrons separate from those producing the radio-IR emission. These two models imply radically different conditions in the large scale jet in terms of jet speed and maximum energy of the particle acceleration mechanism, with important implications for the impact of the jet on the larger-scale environment. Georganopoulos et al. (2006) proposed a diagnostic based on a fundamental difference between these two models: the production of synchrotron X-rays requires multi-TeV electrons, while the EC/CMB model requires a cutoff in the electron energy distribution below TeV energies. This has significant implications for the gamma-ray emission predicted by these two models. Here we present new Fermi observations that put an upper limit on the gamma-ray flux from the large-scale jet of 3C 273 that clearly violates the flux expected from the IC/CMB X-ray interpretation found by extrapolation of the UV to X-ray spectrum of knot A, thus ruling out the IC/CMB interpretation entirely for this source. Further, the Fermi upper limit constraints the Doppler beaming factor delta <5.

Reionization and the cosmic microwave background in an open universe

NASA Technical Reports Server (NTRS)

Persi, Fred M.

1995-01-01

If the universe was reionized at high reshift (z greater than or approximately equal to 30) or never recombined, then photon-electron scattering can erase fluctuations in the cosmic microwave background at scales less than or approximately equal to 1 deg. Peculiar motion at the surface of last scattering will then have given rise to new anisotropy at the 1 min level through the Vishniac effect. Here the observed fluctuations in galaxy counts are extrapolated to high redshifts using linear theory, and the expected anisotropy is computed. The predicted level of anisotropies is a function of Omega(sub 0) and the ratio of the density in ionized baryons to the critical density and is shown to depend strongly on the large- and small-scale power. It is not possible to make general statements about the viability of all reionized models based on current observations, but it is possible to rule out specific models for structure formation, particularly those with high baryonic content or small-scale power. The induced fluctuations are shown to scale with cosmological parameters and optical depth.

Cluster Lensing with the BTC

NASA Astrophysics Data System (ADS)

Fischer, P.

1997-12-01

Weak distortions of background galaxies are rapidly emerging as a powerful tool for the measurement of galaxy cluster mass distributions. Lensing based studies have the advantage of being direct measurements of mass and are not model-dependent as are other techniques (X-ray, radial velocities). To date studies have been limited by CCD field size meaning that full coverage of the clusters out to the virial radii and beyond has not been possible. Probing this large radius region is essential for testing models of large scale structure formation. New wide field CCD mosaics, for the first time, allow mass measurements out to very large radius. We have obtained images for a sample of clusters with the ``Big Throughput Camera'' (BTC) on the CTIO 4m. This camera comprises four thinned SITE 2048(2) CCDs, each 15arcmin on a side for a total area of one quarter of a square degree. We have developed an automated reduction pipeline which: 1) corrects for spatial distortions, 2) corrects for PSF anisotropy, 3) determines relative scaling and background levels, and 4) combines multiple exposures. In this poster we will present some preliminary results of our cluster lensing study. This will include radial mass and light profiles and 2-d mass and galaxy density maps.

Application of stochastic models in identification and apportionment of heavy metal pollution sources in the surface soils of a large-scale region.

PubMed

Hu, Yuanan; Cheng, Hefa

2013-04-16

As heavy metals occur naturally in soils at measurable concentrations and their natural background contents have significant spatial variations, identification and apportionment of heavy metal pollution sources across large-scale regions is a challenging task. Stochastic models, including the recently developed conditional inference tree (CIT) and the finite mixture distribution model (FMDM), were applied to identify the sources of heavy metals found in the surface soils of the Pearl River Delta, China, and to apportion the contributions from natural background and human activities. Regression trees were successfully developed for the concentrations of Cd, Cu, Zn, Pb, Cr, Ni, As, and Hg in 227 soil samples from a region of over 7.2 × 10(4) km(2) based on seven specific predictors relevant to the source and behavior of heavy metals: land use, soil type, soil organic carbon content, population density, gross domestic product per capita, and the lengths and classes of the roads surrounding the sampling sites. The CIT and FMDM results consistently indicate that Cd, Zn, Cu, Pb, and Cr in the surface soils of the PRD were contributed largely by anthropogenic sources, whereas As, Ni, and Hg in the surface soils mostly originated from the soil parent materials.

Parallel and serial computing tools for testing single-locus and epistatic SNP effects of quantitative traits in genome-wide association studies

PubMed Central

Ma, Li; Runesha, H Birali; Dvorkin, Daniel; Garbe, John R; Da, Yang

2008-01-01

Background Genome-wide association studies (GWAS) using single nucleotide polymorphism (SNP) markers provide opportunities to detect epistatic SNPs associated with quantitative traits and to detect the exact mode of an epistasis effect. Computational difficulty is the main bottleneck for epistasis testing in large scale GWAS. Results The EPISNPmpi and EPISNP computer programs were developed for testing single-locus and epistatic SNP effects on quantitative traits in GWAS, including tests of three single-locus effects for each SNP (SNP genotypic effect, additive and dominance effects) and five epistasis effects for each pair of SNPs (two-locus interaction, additive × additive, additive × dominance, dominance × additive, and dominance × dominance) based on the extended Kempthorne model. EPISNPmpi is the parallel computing program for epistasis testing in large scale GWAS and achieved excellent scalability for large scale analysis and portability for various parallel computing platforms. EPISNP is the serial computing program based on the EPISNPmpi code for epistasis testing in small scale GWAS using commonly available operating systems and computer hardware. Three serial computing utility programs were developed for graphical viewing of test results and epistasis networks, and for estimating CPU time and disk space requirements. Conclusion The EPISNPmpi parallel computing program provides an effective computing tool for epistasis testing in large scale GWAS, and the epiSNP serial computing programs are convenient tools for epistasis analysis in small scale GWAS using commonly available computer hardware. PMID:18644146

Cosmic microwave background polarimetry with ABS and ACT: Instrumental design, characterization, and analysis

NASA Astrophysics Data System (ADS)

Simon, Sara Michelle

The LCDM model of the universe is supported by an abundance of astronomical observations, but it does not confirm a period of inflation in the early universe or explain the nature of dark energy and dark matter. The polarization of the cosmic microwave background (CMB) may hold the key to addressing these profound questions. If a period of inflation occurred in the early universe, it could have left a detectable odd-parity pattern called B-modes in the polarization of the CMB on large angular scales. Additionally, the CMB can be used to probe the structure of the universe on small angular scales through lensing and the detection of galaxy clusters and their motions via the Sunyaev-Zel'dovich effect, which can improve our understanding of neutrinos, dark matter, and dark energy. The Atacama B-mode Search (ABS) instrument was a cryogenic crossed-Dragone telescope located at an elevation of 5190m in the Atacama Desert in Chile that observed from February 2012 until October 2014. ABS searched on degree-angular scales for inflationary B-modes in the CMB and pioneered the use of a rapidly-rotating half-wave plate (HWP), which modulates the polarization of incoming light to permit the measurement of celestial polarization on large angular scales that would otherwise be obscured by 1/f noise from the atmosphere. Located next to ABS in the Atacama is the Atacama Cosmology Telescope (ACT), which is an off-axis Gregorian telescope. Its large 6m primary mirror facilitates measurements of the CMB on small angular scales. HWPs are baselined for use with the upgraded polarization-sensitive camera for ACT, called Advanced ACTPol, to extend observations of the polarized CMB to larger angular scales while also retaining sensitivity to small angular scales. The B-mode signal is extremely faint, and measuring it poses an instrumental challenge that requires the development of new technologies and well-characterized instruments. I will discuss the use of novel instrumentation and methods on the ABS telescope and Advanced ACTPol, the characterization of the ABS instrument, and the first two seasons of ABS data, including an overview of the data selection process.

A Survey of Residents' Perceptions of the Effect of Large-Scale Economic Developments on Perceived Safety, Violence, and Economic Benefits

PubMed Central

Geller, Ruth; Bear, Todd M.; Foulds, Abigail L.; Duell, Jessica; Sharma, Ravi

2015-01-01

Background. Emerging research highlights the promise of community- and policy-level strategies in preventing youth violence. Large-scale economic developments, such as sports and entertainment arenas and casinos, may improve the living conditions, economics, public health, and overall wellbeing of area residents and may influence rates of violence within communities. Objective. To assess the effect of community economic development efforts on neighborhood residents' perceptions on violence, safety, and economic benefits. Methods. Telephone survey in 2011 using a listed sample of randomly selected numbers in six Pittsburgh neighborhoods. Descriptive analyses examined measures of perceived violence and safety and economic benefit. Responses were compared across neighborhoods using chi-square tests for multiple comparisons. Survey results were compared to census and police data. Results. Residents in neighborhoods with the large-scale economic developments reported more casino-specific and arena-specific economic benefits. However, 42% of participants in the neighborhood with the entertainment arena felt there was an increase in crime, and 29% of respondents from the neighborhood with the casino felt there was an increase. In contrast, crime decreased in both neighborhoods. Conclusions. Large-scale economic developments have a direct influence on the perception of violence, despite actual violence rates. PMID:26273310

Sterile neutrinos with secret interactions—lasting friendship with cosmology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chu, Xiaoyong; Dasgupta, Basudeb; Kopp, Joachim, E-mail: xchu@ictp.it, E-mail: bdasgupta@theory.tifr.res.in, E-mail: jkopp@uni-mainz.de

Sterile neutrinos with mass ≅ 1 eV and order 10% mixing with active neutrinos have been proposed as a solution to anomalies in neutrino oscillation data, but are tightly constrained by cosmological limits. It was recently shown that these constraints are avoided if sterile neutrinos couple to a new MeV-scale gauge boson A'. However, even this scenario is restricted by structure formation constraints when A'-mediated collisional processes lead to efficient active-to-sterile neutrino conversion after neutrinos have decoupled. In view of this, we reevaluate in this paper the viability of sterile neutrinos with such ''secret'' interactions. We carefully dissect their evolution inmore » the early Universe, including the various production channels and the expected modifications to large scale structure formation. We argue that there are two regions in parameter space—one at very small A' coupling, one at relatively large A' coupling—where all constraints from big bang nucleosynthesis (BBN), cosmic microwave background (CMB), and large scale structure (LSS) data are satisfied. Interestingly, the large A' coupling region is precisely the region that was previously shown to have potentially important consequences for the small scale structure of dark matter halos if the A' boson couples also to the dark matter in the Universe.« less

SPECTRAL LINE DE-CONFUSION IN AN INTENSITY MAPPING SURVEY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheng, Yun-Ting; Bock, James; Bradford, C. Matt

2016-12-01

Spectral line intensity mapping (LIM) has been proposed as a promising tool to efficiently probe the cosmic reionization and the large-scale structure. Without detecting individual sources, LIM makes use of all available photons and measures the integrated light in the source confusion limit to efficiently map the three-dimensional matter distribution on large scales as traced by a given emission line. One particular challenge is the separation of desired signals from astrophysical continuum foregrounds and line interlopers. Here we present a technique to extract large-scale structure information traced by emission lines from different redshifts, embedded in a three-dimensional intensity mapping data cube.more » The line redshifts are distinguished by the anisotropic shape of the power spectra when projected onto a common coordinate frame. We consider the case where high-redshift [C ii] lines are confused with multiple low-redshift CO rotational lines. We present a semi-analytic model for [C ii] and CO line estimates based on the cosmic infrared background measurements, and show that with a modest instrumental noise level and survey geometry, the large-scale [C ii] and CO power spectrum amplitudes can be successfully extracted from a confusion-limited data set, without external information. We discuss the implications and limits of this technique for possible LIM experiments.« less

Paleoclimate

USGS Publications Warehouse

Bartlein, Patrick J.; Hostetler, Steven W.; Alder, Jay R.; Ohring, G.

2014-01-01

As host to one of the major continental-scale ice sheets, and with considerable spatial variability of climate related to its physiography and location, North America has experienced a wide range of climates over time. The aim of this chapter is to review the history of those climate variations, focusing in particular on the continental-scale climatic variations between the Last Glacial Maximum (LGM, ca. 21,000 years ago or 21 ka) and the present, which were as large in amplitude as any experienced over a similar time span during the past several million years. As background to that discussion, the climatic variations over the Cenozoic (the past 65.5 Myr, or 65.5 Ma to present) that led ultimately to the onset of Northern Hemisphere glaciation at 2.59 Ma will also be discussed. Superimposed on the large-amplitude, broad-scale variations from the LGM to present, are climatic variations on millennial-to-decadal scales, and these will be reviewed in particular for the Holocene (11.7 ka to present) and the past millennium.

Detection of the baryon acoustic peak in the large-scale correlation function of SDSS luminous red galaxies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eisenstein, Daniel J.; Zehavi, Idit; Hogg, David W.

2005-01-01

We present the large-scale correlation function measured from a spectroscopic sample of 46,748 luminous red galaxies from the Sloan Digital Sky Survey. The survey region covers 0.72h{sup -3} Gpc{sup 3} over 3816 square degrees and 0.16 < z < 0.47, making it the best sample yet for the study of large-scale structure. We find a well-detected peak in the correlation function at 100h{sup -1} Mpc separation that is an excellent match to the predicted shape and location of the imprint of the recombination-epoch acoustic oscillations on the low-redshift clustering of matter. This detection demonstrates the linear growth of structure bymore » gravitational instability between z {approx} 1000 and the present and confirms a firm prediction of the standard cosmological theory. The acoustic peak provides a standard ruler by which we can measure the ratio of the distances to z = 0.35 and z = 1089 to 4% fractional accuracy and the absolute distance to z = 0.35 to 5% accuracy. From the overall shape of the correlation function, we measure the matter density {Omega}{sub m}h{sup 2} to 8% and find agreement with the value from cosmic microwave background (CMB) anisotropies. Independent of the constraints provided by the CMB acoustic scale, we find {Omega}{sub m} = 0.273 {+-} 0.025 + 0.123(1 + w{sub 0}) + 0.137{Omega}{sub K}. Including the CMB acoustic scale, we find that the spatial curvature is {Omega}{sub K} = -0.010 {+-} 0.009 if the dark energy is a cosmological constant. More generally, our results provide a measurement of cosmological distance, and hence an argument for dark energy, based on a geometric method with the same simple physics as the microwave background anisotropies. The standard cosmological model convincingly passes these new and robust tests of its fundamental properties.« less

Reassessing the "traditional background hypothesis" for elevated MMPI and MMPI-2 Lie-scale scores.

PubMed

Rosen, Gerald M; Baldwin, Scott A; Smith, Ronald E

2016-10-01

The Lie (L) scale of the Minnesota Multiphasic Personality Inventory (MMPI) is widely regarded as a measure of conscious attempts to deny common human foibles and to present oneself in an unrealistically positive light. At the same time, the current MMPI-2 manual states that "traditional" and religious backgrounds can account for elevated L scale scores as high as 65T-79T, thereby tempering impression management interpretations for faith-based individuals. To assess the validity of the traditional background hypothesis, we reviewed 11 published studies that employed the original MMPI with religious samples and found that only 1 obtained an elevated mean L score. We then conducted a meta-analysis of 12 published MMPI-2 studies in which we compared L scores of religious samples to the test normative group. The meta-analysis revealed large between-study heterogeneity (I2 = 87.1), L scale scores for religious samples that were somewhat higher but did not approach the upper limits specified in the MMPI-2 manual, and an overall moderate effect size (d¯ = 0.54, p < .001; 95% confidence interval [0.37, 0.70]). Our analyses indicated that religious-group membership accounts, on average, for elevations on L of about 5 t-score points. Whether these scores reflect conscious "fake good" impression management or religious-based virtuousness remains unanswered. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Perturbation theory for cosmologies with nonlinear structure

NASA Astrophysics Data System (ADS)

Goldberg, Sophia R.; Gallagher, Christopher S.; Clifton, Timothy

2017-11-01

The next generation of cosmological surveys will operate over unprecedented scales, and will therefore provide exciting new opportunities for testing general relativity. The standard method for modelling the structures that these surveys will observe is to use cosmological perturbation theory for linear structures on horizon-sized scales, and Newtonian gravity for nonlinear structures on much smaller scales. We propose a two-parameter formalism that generalizes this approach, thereby allowing interactions between large and small scales to be studied in a self-consistent and well-defined way. This uses both post-Newtonian gravity and cosmological perturbation theory, and can be used to model realistic cosmological scenarios including matter, radiation and a cosmological constant. We find that the resulting field equations can be written as a hierarchical set of perturbation equations. At leading-order, these equations allow us to recover a standard set of Friedmann equations, as well as a Newton-Poisson equation for the inhomogeneous part of the Newtonian energy density in an expanding background. For the perturbations in the large-scale cosmology, however, we find that the field equations are sourced by both nonlinear and mode-mixing terms, due to the existence of small-scale structures. These extra terms should be expected to give rise to new gravitational effects, through the mixing of gravitational modes on small and large scales—effects that are beyond the scope of standard linear cosmological perturbation theory. We expect our formalism to be useful for accurately modeling gravitational physics in universes that contain nonlinear structures, and for investigating the effects of nonlinear gravity in the era of ultra-large-scale surveys.

The implications of the COBE diffuse microwave radiation results for cosmic strings

NASA Technical Reports Server (NTRS)

Bennett, David P.; Stebbins, Albert; Bouchet, Francois R.

1992-01-01

We compare the anisotropies in the cosmic microwave background radiation measured by the COBE experiment to those predicted by cosmic string theories. We use an analytic model for the Delta T/T power spectrum that is based on our previous numerical simulations of strings, under the assumption that cosmic strings are the sole source of the measured anisotropy. This implies a value for the string mass per unit length of 1.5 +/- 0.5 x 10 exp -6 C-squared/G. This is within the range of values required for cosmic strings to successfully seed the formation of large-scale structures in the universe. These results clearly encourage further studies of Delta T/T and large-scale structure in the cosmic string model.

Electromagnetic Design of Feedhorn-Coupled Transition-Edge Sensors for Cosmic Microwave Background Polarimetery

NASA Technical Reports Server (NTRS)

Chuss, David T.

2011-01-01

Observations of the cosmic microwave background (CMB) provide a powerful tool for probing the evolution of the early universe. Specifically, precision measurement of the polarization of the CMB enables a direct test for cosmic inflation. A key technological element on the path to the measurement of this faint signal is the capability to produce large format arrays of background-limited detectors. We describe the electromagnetic design of feedhorn-coupled, TES-based sensors. Each linear orthogonal polarization from the feed horn is coupled to a superconducting microstrip line via a symmetric planar orthomode transducer (OMT). The symmetric OMT design allows for highly-symmetric beams with low cross-polarization over a wide bandwidth. In addition, this architecture enables a single microstrip filter to define the passband for each polarization. Care has been taken in the design to eliminate stray coupling paths to the absorbers. These detectors will be fielded in the Cosmology Large Angular Scale Surveyor (CLASS).

Influence of a large-scale field on energy dissipation in magnetohydrodynamic turbulence

NASA Astrophysics Data System (ADS)

Zhdankin, Vladimir; Boldyrev, Stanislav; Mason, Joanne

2017-07-01

In magnetohydrodynamic (MHD) turbulence, the large-scale magnetic field sets a preferred local direction for the small-scale dynamics, altering the statistics of turbulence from the isotropic case. This happens even in the absence of a total magnetic flux, since MHD turbulence forms randomly oriented large-scale domains of strong magnetic field. It is therefore customary to study small-scale magnetic plasma turbulence by assuming a strong background magnetic field relative to the turbulent fluctuations. This is done, for example, in reduced models of plasmas, such as reduced MHD, reduced-dimension kinetic models, gyrokinetics, etc., which make theoretical calculations easier and numerical computations cheaper. Recently, however, it has become clear that the turbulent energy dissipation is concentrated in the regions of strong magnetic field variations. A significant fraction of the energy dissipation may be localized in very small volumes corresponding to the boundaries between strongly magnetized domains. In these regions, the reduced models are not applicable. This has important implications for studies of particle heating and acceleration in magnetic plasma turbulence. The goal of this work is to systematically investigate the relationship between local magnetic field variations and magnetic energy dissipation, and to understand its implications for modelling energy dissipation in realistic turbulent plasmas.

Cosmology Large Angular Scale Surveyor (CLASS) Focal Plane Development

NASA Technical Reports Server (NTRS)

Chuss, D. T.; Ali, A.; Amiri, M.; Appel, J.; Bennett, C. L.; Colazo, F.; Denis, K. L.; Dunner, R.; Essinger-Hileman, T.; Eimer, J.;

Cosmology Large Angular Scale Surveyor (CLASS) Focal Plane Development

NASA Astrophysics Data System (ADS)

Chuss, D. T.; Ali, A.; Amiri, M.; Appel, J.; Bennett, C. L.; Colazo, F.; Denis, K. L.; Dünner, R.; Essinger-Hileman, T.; Eimer, J.; Fluxa, P.; Gothe, D.; Halpern, M.; Harrington, K.; Hilton, G.; Hinshaw, G.; Hubmayr, J.; Iuliano, J.; Marriage, T. A.; Miller, N.; Moseley, S. H.; Mumby, G.; Petroff, M.; Reintsema, C.; Rostem, K.; U-Yen, K.; Watts, D.; Wagner, E.; Wollack, E. J.; Xu, Z.; Zeng, L.

2016-08-01

The Cosmology Large Angular Scale Surveyor (CLASS) will measure the polarization of the Cosmic Microwave Background to search for and characterize the polarized signature of inflation. CLASS will operate from the Atacama Desert and observe ˜ 70 % of the sky. A variable-delay polarization modulator provides modulation of the polarization at ˜ 10 Hz to suppress the 1/ f noise of the atmosphere and enable the measurement of the large angular scale polarization modes. The measurement of the inflationary signal across angular scales that spans both the recombination and reionization features allows a test of the predicted shape of the polarized angular power spectra in addition to a measurement of the energy scale of inflation. CLASS is an array of telescopes covering frequencies of 38, 93, 148, and 217 GHz. These frequencies straddle the foreground minimum and thus allow the extraction of foregrounds from the primordial signal. Each focal plane contains feedhorn-coupled transition-edge sensors that simultaneously detect two orthogonal linear polarizations. The use of single-crystal silicon as the dielectric for the on-chip transmission lines enables both high efficiency and uniformity in fabrication. Integrated band definition has been implemented that both controls the bandpass of the single-mode transmission on the chip and prevents stray light from coupling to the detectors.

The Reasons, Motivation, and Selection of Approach to the Consolidation of Primary and Secondary Schools in Rural Areas

ERIC Educational Resources Information Center

Xianzuo, Fan

2013-01-01

Beginning in the late 1990s and especially since 2000, a new round of large-scale school consolidation has been introduced in rural communities in China. What is the background of this policy initiative? How has it been introduced and implemented? This article examines these issues.

Outcomes and Costs of Residential Services for Adults with Intellectual Disabilities in Taiwan: A Comparative Evaluation

ERIC Educational Resources Information Center

Chou, Yueh-Ching; Lin, Li-Chan; Pu, Cheng-Yun; Lee, Wan-Ping; Chang, Shu-Chuan

2008-01-01

Background: The disability policy in Taiwan has traditionally emphasized residential care in large institutions and, more recently, medium-sized group homes. This paper compares the relative costs, services provided and outcomes between the traditional institutions, medium-sized group homes and new small-scale community living units that were…

Some Thoughts About Water Analysis in Shipboard Steam Propulsion Systems for Marine Engineering Students.

ERIC Educational Resources Information Center

Schlenker, Richard M.; And Others

Information is presented about the problems involved in using sea water in the steam propulsion systems of large, modern ships. Discussions supply background chemical information concerning the problems of corrosion, scale buildup, and sludge production. Suggestions are given for ways to maintain a good water treatment program to effectively deal…

Promoting Reading Attitudes of Girls and Boys: A New Challenge for Educational Policy? Multi-Group Analyses across Four European Countries

ERIC Educational Resources Information Center

Nonte, Sonja; Hartwich, Lea; Willems, Ariane S.

2018-01-01

Background: Numerous studies have investigated the relationships between various student, home and contextual factors and reading achievement. However, the relationship between such factors and reading attitudes has been investigated far less, despite the fact that theoretical frameworks of large-scale assessments and school effectiveness research…

Chronic Physical Illness and Mental Health in Children. Results from a Large-Scale Population Study

ERIC Educational Resources Information Center

Hysing, Mari; Elgen, Irene; Gillberg, Christopher; Lie, Stein Atle; Lundervold, Astri J.

2007-01-01

Background: The aim of the present study was to evaluate the sensitivity and specificity of the Strengths and Difficulties Questionnaire (SDQ) in detecting emotional and behavioural problems among children with chronic illness (CI). Methods: Parents and teachers of a population of primary school children in Norway (n = 9430) completed a…

Personality, Cognitive Skills and Life Outcomes: Evidence from the Polish Follow-Up Study to PIAAC

ERIC Educational Resources Information Center

Palczynska, Marta; Swist, Karolina

2018-01-01

Background: There is a growing literature providing evidence on the importance of non-cognitive skills for life outcomes. However, to date there is limited evidence on the gains from incorporating such measures into large-scale competence surveys. Methods: We investigate the relationship between personality traits and eight important life…

A Scoping Review to Address the Culture of Concussion in Youth and High School Sports

ERIC Educational Resources Information Center

Sarmiento, Kelly; Donnell, Zoe; Hoffman, Rosanne

2017-01-01

Background: In 2013, the National Academy of Sciences emphasized the need to develop, implement, and evaluate effective large-scale educational strategies to improve the culture of concussion in youth and high school sports. In support of this recommendation, in this article we summarize research on factors that contribute to the culture of…

Community Partnership to Address Snack Quality and Cost in After-School Programs

ERIC Educational Resources Information Center

Beets, Michael W.; Tilley, Falon; Turner-McGrievy, Gabrielle; Weaver, Robert G.; Jones, Sonya

2014-01-01

Background: Policies call on after-school programs (ASPs) to serve more nutritious snacks. A major barrier for improving snack quality is cost. This study describes the impact on snack quality and expenditures from a community partnership between ASPs and local grocery stores. Methods: Four large-scale ASPs (serving ~500 children, aged 6-12?years,…

Adult Siblings of Individuals with Down Syndrome versus with Autism: Findings from a Large-Scale US Survey

ERIC Educational Resources Information Center

Hodapp, R. M.; Urbano, R. C.

2007-01-01

Background: As adults with Down syndrome live increasingly longer lives, their adult siblings will most likely assume caregiving responsibilities. Yet little is known about either the sibling relationship or the general functioning of these adult siblings. Using a national, web-based survey, this study compared adult siblings of individuals with…

Screening for Psychosocial Distress amongst War-Affected Children: Cross-Cultural Construct Validity of the CPDS

ERIC Educational Resources Information Center

Jordans, M. J. D.; Komproe, I. H.; Tol, W. A.; De Jong, J. T. V. M.

2009-01-01

Background: Large-scale psychosocial interventions in complex emergencies call for a screening procedure to identify individuals at risk. To date there are no screening instruments that are developed within low- and middle-income countries and validated for that purpose. The present study assesses the cross-cultural validity of the brief,…

Class Size Effects on Reading Achievement Using PIRLS Data: Evidence from Greece

ERIC Educational Resources Information Center

Konstantopoulos, Spyros; Traynor, Anne

2014-01-01

Background/Context: The effects of class size on student achievement have gained considerable attention in education research and policy, especially over the last 30 years. Perhaps the best evidence about the effects of class size thus far has been produced from analyses of Project STAR data, a large-scale experiment where students and teachers…

Iron, zinc, folate, and vitamin B12 status increased among women and children in Yaounde and Douala, Cameroon, one year after introducing fortified wheat flour

USDA-ARS?s Scientific Manuscript database

Background: Few data, to our knowledge, are available on the effectiveness of large-scale food fortification programs. Objective: We assessed the impact of mandatory wheat flour fortification on micronutrient status in Yaounde and Douala, Cameroon. Methods: We conducted representative surveys 2 y ...

Large angular scale CMB anisotropy from an excited initial mode

NASA Astrophysics Data System (ADS)

Sojasi, A.; Mohsenzadeh, M.; Yusofi, E.

2016-07-01

According to inflationary cosmology, the CMB anisotropy gives an opportunity to test predictions of new physics hypotheses. The initial state of quantum fluctuations is one of the important options at high energy scale, as it can affect observables such as the CMB power spectrum. In this study a quasi-de Sitter inflationary background with approximate de Sitter mode function built over the Bunch-Davies mode is applied to investigate the scale-dependency of the CMB anisotropy. The recent Planck constraint on spectral index motivated us to examine the effect of a new excited mode function (instead of pure de Sitter mode) on the CMB anisotropy at large angular scales. In so doing, it is found that the angular scale-invariance in the CMB temperature fluctuations is broken and in the limit ℓ < 200 a tiny deviation appears. Also, it is shown that the power spectrum of CMB anisotropy is dependent on a free parameter with mass dimension H << M * < M p and on the slow-roll parameter ɛ. Supported by the Islamic Azad University, Rasht Branch, Rasht, Iran

Modulation of cosmic microwave background polarization with a warm rapidly rotating half-wave plate on the Atacama B-Mode Search instrument.

PubMed

Kusaka, A; Essinger-Hileman, T; Appel, J W; Gallardo, P; Irwin, K D; Jarosik, N; Nolta, M R; Page, L A; Parker, L P; Raghunathan, S; Sievers, J L; Simon, S M; Staggs, S T; Visnjic, K

2014-02-01

We evaluate the modulation of cosmic microwave background polarization using a rapidly rotating, half-wave plate (HWP) on the Atacama B-Mode Search. After demodulating the time-ordered-data (TOD), we find a significant reduction of atmospheric fluctuations. The demodulated TOD is stable on time scales of 500-1000 s, corresponding to frequencies of 1-2 mHz. This facilitates recovery of cosmological information at large angular scales, which are typically available only from balloon-borne or satellite experiments. This technique also achieves a sensitive measurement of celestial polarization without differencing the TOD of paired detectors sensitive to two orthogonal linear polarizations. This is the first demonstration of the ability to remove atmospheric contamination at these levels from a ground-based platform using a rapidly rotating HWP.

Effects of the Bermuda High and the Great Plains low-level jet upon background and peak ozone concentrations in Texas urban areas

NASA Astrophysics Data System (ADS)

Estes, M. J.; Wang, Y.; Lei, R.; Wang, S. C.; Jia, B.

2017-12-01

Previous studies have established that the westward extent of the Bermuda High is strongly linked to the ozone concentrations in Houston. This study examines the linkages between the Bermuda High, the Great Plains low-level jet, background ozone in the eastern half of Texas, and local contributions to peak ozone in Texas urban areas. Analysis of North American Regional Reanalysis (NARR) wind and pressure fields will be used to establish the presence and strength of synoptic-scale weather features, and this information will be used with ozone data from air quality networks to determine the effects upon the seasonal and interannual variations of ozone. Quantification of the effects of large-scale meteorological factors will improve understanding of the causes of ozone variations, including decadal trends in Texas cities.

Nearly scale invariant spectrum of gravitational radiation from global phase transitions.

PubMed

Jones-Smith, Katherine; Krauss, Lawrence M; Mathur, Harsh

2008-04-04

Using a large N sigma model approximation we explicitly calculate the power spectrum of gravitational waves arising from a global phase transition in the early Universe and we confirm that it is scale invariant, implying an observation of such a spectrum may not be a unique feature of inflation. Moreover, the predicted amplitude can be over 3 orders of magnitude larger than the naive dimensional estimate, implying that even a transition that occurs after inflation may dominate in cosmic microwave background polarization or other gravity wave signals.

Controlled Electron Injection into Plasma Accelerators and SpaceCharge Estimates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fubiani, Gwenael G.J.

2005-09-01

Plasma based accelerators are capable of producing electron sources which are ultra-compact (a few microns) and high energies (up to hundreds of MeVs) in much shorter distances than conventional accelerators. This is due to the large longitudinal electric field that can be excited without the limitation of breakdown as in RF structures.The characteristic scale length of the accelerating field is the plasma wavelength and for typical densities ranging from 10 18 - 10 19 cm -3, the accelerating fields and scale length can hence be on the order of 10-100GV/m and 10-40 μm, respectively. The production of quasimonoenergetic beams wasmore » recently obtained in a regime relying on self-trapping of background plasma electrons, using a single laser pulse for wakefield generation. In this dissertation, we study the controlled injection via the beating of two lasers (the pump laser pulse creating the plasma wave and a second beam being propagated in opposite direction) which induce a localized injection of background plasma electrons. The aim of this dissertation is to describe in detail the physics of optical injection using two lasers, the characteristics of the electron beams produced (the micrometer scale plasma wavelength can result in femtosecond and even attosecond bunches) as well as a concise estimate of the effects of space charge on the dynamics of an ultra-dense electron bunch with a large energy spread.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Capela, Fabio; Ramazanov, Sabir, E-mail: fc403@cam.ac.uk, E-mail: Sabir.Ramazanov@ulb.ac.be

At large scales and for sufficiently early times, dark matter is described as a pressureless perfect fluid—dust— non-interacting with Standard Model fields. These features are captured by a simple model with two scalars: a Lagrange multiplier and another playing the role of the velocity potential. That model arises naturally in some gravitational frameworks, e.g., the mimetic dark matter scenario. We consider an extension of the model by means of higher derivative terms, such that the dust solutions are preserved at the background level, but there is a non-zero sound speed at the linear level. We associate this Modified Dust withmore » dark matter, and study the linear evolution of cosmological perturbations in that picture. The most prominent effect is the suppression of their power spectrum for sufficiently large cosmological momenta. This can be relevant in view of the problems that cold dark matter faces at sub-galactic scales, e.g., the missing satellites problem. At even shorter scales, however, perturbations of Modified Dust are enhanced compared to the predictions of more common particle dark matter scenarios. This is a peculiarity of their evolution in radiation dominated background. We also briefly discuss clustering of Modified Dust. We write the system of equations in the Newtonian limit, and sketch the possible mechanism which could prevent the appearance of caustic singularities. The same mechanism may be relevant in light of the core-cusp problem.« less

Evolution of Scaling Emergence in Large-Scale Spatial Epidemic Spreading

PubMed Central

Wang, Lin; Li, Xiang; Zhang, Yi-Qing; Zhang, Yan; Zhang, Kan

2011-01-01

Background Zipf's law and Heaps' law are two representatives of the scaling concepts, which play a significant role in the study of complexity science. The coexistence of the Zipf's law and the Heaps' law motivates different understandings on the dependence between these two scalings, which has still hardly been clarified. Methodology/Principal Findings In this article, we observe an evolution process of the scalings: the Zipf's law and the Heaps' law are naturally shaped to coexist at the initial time, while the crossover comes with the emergence of their inconsistency at the larger time before reaching a stable state, where the Heaps' law still exists with the disappearance of strict Zipf's law. Such findings are illustrated with a scenario of large-scale spatial epidemic spreading, and the empirical results of pandemic disease support a universal analysis of the relation between the two laws regardless of the biological details of disease. Employing the United States domestic air transportation and demographic data to construct a metapopulation model for simulating the pandemic spread at the U.S. country level, we uncover that the broad heterogeneity of the infrastructure plays a key role in the evolution of scaling emergence. Conclusions/Significance The analyses of large-scale spatial epidemic spreading help understand the temporal evolution of scalings, indicating the coexistence of the Zipf's law and the Heaps' law depends on the collective dynamics of epidemic processes, and the heterogeneity of epidemic spread indicates the significance of performing targeted containment strategies at the early time of a pandemic disease. PMID:21747932

Development of a database system for mapping insertional mutations onto the mouse genome with large-scale experimental data

PubMed Central

2009-01-01

Background Insertional mutagenesis is an effective method for functional genomic studies in various organisms. It can rapidly generate easily tractable mutations. A large-scale insertional mutagenesis with the piggyBac (PB) transposon is currently performed in mice at the Institute of Developmental Biology and Molecular Medicine (IDM), Fudan University in Shanghai, China. This project is carried out via collaborations among multiple groups overseeing interconnected experimental steps and generates a large volume of experimental data continuously. Therefore, the project calls for an efficient database system for recording, management, statistical analysis, and information exchange. Results This paper presents a database application called MP-PBmice (insertional mutation mapping system of PB Mutagenesis Information Center), which is developed to serve the on-going large-scale PB insertional mutagenesis project. A lightweight enterprise-level development framework Struts-Spring-Hibernate is used here to ensure constructive and flexible support to the application. The MP-PBmice database system has three major features: strict access-control, efficient workflow control, and good expandability. It supports the collaboration among different groups that enter data and exchange information on daily basis, and is capable of providing real time progress reports for the whole project. MP-PBmice can be easily adapted for other large-scale insertional mutation mapping projects and the source code of this software is freely available at http://www.idmshanghai.cn/PBmice. Conclusion MP-PBmice is a web-based application for large-scale insertional mutation mapping onto the mouse genome, implemented with the widely used framework Struts-Spring-Hibernate. This system is already in use by the on-going genome-wide PB insertional mutation mapping project at IDM, Fudan University. PMID:19958505

Local gravity and large-scale structure

NASA Technical Reports Server (NTRS)

Juszkiewicz, Roman; Vittorio, Nicola; Wyse, Rosemary F. G.

1990-01-01

The magnitude and direction of the observed dipole anisotropy of the galaxy distribution can in principle constrain the amount of large-scale power present in the spectrum of primordial density fluctuations. This paper confronts the data, provided by a recent redshift survey of galaxies detected by the IRAS satellite, with the predictions of two cosmological models with very different levels of large-scale power: the biased Cold Dark Matter dominated model (CDM) and a baryon-dominated model (BDM) with isocurvature initial conditions. Model predictions are investigated for the Local Group peculiar velocity, v(R), induced by mass inhomogeneities distributed out to a given radius, R, for R less than about 10,000 km/s. Several convergence measures for v(R) are developed, which can become powerful cosmological tests when deep enough samples become available. For the present data sets, the CDM and BDM predictions are indistinguishable at the 2 sigma level and both are consistent with observations. A promising discriminant between cosmological models is the misalignment angle between v(R) and the apex of the dipole anisotropy of the microwave background.

Enhanced polarization of the cosmic microwave background radiation from thermal gravitational waves.

PubMed

Bhattacharya, Kaushik; Mohanty, Subhendra; Nautiyal, Akhilesh

2006-12-22

If inflation was preceded by a radiation era, then at the time of inflation there will exist a decoupled thermal distribution of gravitons. Gravitational waves generated during inflation will be amplified by the process of stimulated emission into the existing thermal distribution of gravitons. Consequently, the usual zero temperature scale invariant tensor spectrum is modified by a temperature dependent factor. This thermal correction factor amplifies the B-mode polarization of the cosmic microwave background radiation by an order of magnitude at large angles, which may now be in the range of observability of the Wilkinson Microwave Anisotropy Probe.

A Shallow Underground Laboratory for Low-Background Radiation Measurements and Materials Development

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aalseth, Craig E.; Bonicalzi, Ricco; Cantaloub, Michael G.

Abstract: Pacific Northwest National Laboratory recently commissioned a new shallow underground laboratory, located at a depth of approximately 30 meters water-equivalent. This new addition to the small class of radiation measurement laboratories located at modest underground depths worldwide houses the latest generation of custom-made, high-efficiency, low-background gamma-ray spectrometers and gas proportional counters. This manuscript describes the unique capabilities present in the shallow underground laboratory; these include large-scale ultra-pure materials production and a suite of radiation detection systems. Reported data characterize the degree of background reduction achieved through a combination of underground location, graded shielding, and rejection of cosmic-ray events. Wemore » conclude by presenting measurement targets and future opportunities.« less

HOW THE DENSITY ENVIRONMENT CHANGES THE INFLUENCE OF THE DARK MATTER–BARYON STREAMING VELOCITY ON COSMOLOGICAL STRUCTURE FORMATION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ahn, Kyungjin, E-mail: kjahn@chosun.ac.kr

We study the dynamical effect of the relative velocity between dark matter and baryonic fluids, which remained supersonic after the epoch of recombination. The impact of this supersonic motion on the formation of cosmological structures was first formulated by Tseliakhovich and Hirata, in terms of the linear theory of small-scale fluctuations coupled to large-scale, relative velocities in mean-density regions. In their formalism, they limited the large-scale density environment to be that of the global mean density. We improve on their formulation by allowing variation in the density environment as well as the relative velocities. This leads to a new typemore » of coupling between large-scale and small-scale modes. We find that the small-scale fluctuation grows in a biased way: faster in the overdense environment and slower in the underdense environment. We also find that the net effect on the global power spectrum of the density fluctuation is to boost its overall amplitude from the prediction by Tseliakhovich and Hirata. Correspondingly, the conditional mass function of cosmological halos and the halo bias parameter are both affected in a similar way. The discrepancy between our prediction and that of Tseliakhovich and Hirata is significant, and therefore, the related cosmology and high-redshift astrophysics should be revisited. The mathematical formalism of this study can be used for generating cosmological initial conditions of small-scale perturbations in generic, overdense (underdense) background patches.« less

Non-Gaussian microwave background fluctuations from nonlinear gravitational effects

NASA Technical Reports Server (NTRS)

Salopek, D. S.; Kunstatter, G. (Editor)

1991-01-01

Whether the statistics of primordial fluctuations for structure formation are Gaussian or otherwise may be determined if the Cosmic Background Explorer (COBE) Satellite makes a detection of the cosmic microwave-background temperature anisotropy delta T(sub CMB)/T(sub CMB). Non-Gaussian fluctuations may be generated in the chaotic inflationary model if two scalar fields interact nonlinearly with gravity. Theoretical contour maps are calculated for the resulting Sachs-Wolfe temperature fluctuations at large angular scales (greater than 3 degrees). In the long-wavelength approximation, one can confidently determine the nonlinear evolution of quantum noise with gravity during the inflationary epoch because: (1) different spatial points are no longer in causal contact; and (2) quantum gravity corrections are typically small-- it is sufficient to model the system using classical random fields. If the potential for two scalar fields V(phi sub 1, phi sub 2) possesses a sharp feature, then non-Gaussian fluctuations may arise. An explicit model is given where cold spots in delta T(sub CMB)/T(sub CMB) maps are suppressed as compared to the Gaussian case. The fluctuations are essentially scale-invariant.

SPEECH TO FACULTY OF HARVARD-BOSTON SUMMER PROGRAM AT PREPLANNING MEETINGS.

ERIC Educational Resources Information Center

HAIZLIP, HAROLD

THE AREA TO WHICH THIS GROUP OF TEACHERS WILL BE SENT IS CHARACTERIZED BY ITS LARGE INFLUX OF POOR NEGRO FAMILIES WITH POOR CULTURAL BACKGROUNDS. SOME OF THE PROBLEMS OF THIS AREA WILL REQUIRE A BROAD-SCALE, CAREFULLY ANALYZED, AND PLANNED ATTACK WITHIN AND BY PUBLIC SCHOOLS. EVERY SCHOOL HAS A HIDDEN OR SUBLIMINAL CURRICULUM WHICH TEACHES, IN…

The Wide-Scale Implementation of a Support Program for Parents of Children with an Intellectual Disability and Difficult Behaviour

ERIC Educational Resources Information Center

Hudson, Alan; Cameron, Christine; Matthews, Jan

2008-01-01

Background: While there have been several evaluations of programs to help parents manage difficult behaviour of their child with an intellectual disability, little research has focused on the evaluation of such programs when delivered to large populations. Method: The benchmarks recommended by Wiese, Stancliffe, and Hemsley (2005) were used to…

Baby Pictures of the Universe

NASA Technical Reports Server (NTRS)

Bennett, Charles

2004-01-01

The first findings from a year of WMAP satellite operations provide a detailed full sky map of the cosmic microwave background radiation. The observed temperature anisotropy, combined with the associated polarization information, encodes a wealth of cosmological information. The results have implications for the history, content, and evolution of the universe, and its large scale properties. These and other aspects of the mission will be discussed.

An Examination of the RCMAS-2 Scores across Gender, Ethnic Background, and Age in a Large Asian School Sample

ERIC Educational Resources Information Center

Ang, Rebecca P.; Lowe, Patricia A.; Yusof, Noradlin

2011-01-01

The present study investigated the factor structure, reliability, convergent and discriminant validity, and U.S. norms of the Revised Children's Manifest Anxiety Scale, Second Edition (RCMAS-2; C. R. Reynolds & B. O. Richmond, 2008a) scores in a Singapore sample of 1,618 school-age children and adolescents. Although there were small…

Quality Daily Physical Education for the Primary School Student: A Personal Account of the Trois-Rivieres Regional Project

ERIC Educational Resources Information Center

Shephard, Roy J.; Trudeau, Francois

2013-01-01

This article offers a brief and personal account of the historical background, implementation and principal findings from the Trois-Rivieres regional project, a large-scale quasi-experimental intervention that tested the impact of providing a daily hour of specialist-taught quality physical education upon the physical and mental development of…

Use of Native Language and Culture (NLC) in Elementary and Middle School Instruction as a Predictor of Mathematics Achievement

ERIC Educational Resources Information Center

Van Ryzin, Mark J.; Vincent, Claudia G.

2017-01-01

Because students from American Indian/Alaska Native (AI/AN) backgrounds tend to lag behind their peers in academic achievement, researchers have recommended integrating Native Language and Culture (NLC) into instruction. However, existing evidence from large-scale studies finds a "negative" effect of the use of NLC on achievement,…

Effects of "Find Thirty Every Day [R]": Cross-Sectional Findings from a Western Australian Population-Wide Mass Media Campaign, 2008-2010

ERIC Educational Resources Information Center

Leavy, Justine E.; Rosenberg, Michael; Bauman, Adrian E.; Bull, Fiona C.; Giles-Corti, Billie; Shilton, Trevor; Maitland, Clover; Barnes, Rosanne

2013-01-01

Background: Internationally, over the last four decades large-scale mass media campaigns have been delivered to promote physical activity and its associated health benefits. In 2002-2005, the first Western Australian statewide adult physical activity campaign "Find Thirty. It's Not a Big Exercise" was launched. In 2007, a new iteration…

Non-Tenure-Track Faculty's Social Construction of a Supportive Work Environment

ERIC Educational Resources Information Center

Kezar, Adrianna

2013-01-01

Background: The number of non-tenure-track faculty (NTTF), including both full-time (FT) and part-time (PT) positions, has risen to two-thirds of faculty positions across the academy. To date, most of the studies of NTTF have relied on secondary data or large-scale surveys. Few qualitative studies exist that examine the experience, working…

Body Mass Index in Adults with Intellectual Disability: Distribution, Associations and Service Implications--A Population-Based Prevalence Study

ERIC Educational Resources Information Center

Bhaumik, S.; Watson, J. M.; Thorp, C. F.; Tyrer, F.; McGrother, C. W.

2008-01-01

Background: Previous studies of weight problems in adults with intellectual disability (ID) have generally been small or selective and given conflicting results. The objectives of our large-scale study were to identify inequalities in weight problems between adults with ID and the general adult population, and to investigate factors associated…

Association of Aggressive Behaviours with Psychiatric Disorders, Age, Sex and Degree of Intellectual Disability: A Large-Scale Survey

ERIC Educational Resources Information Center

Tsiouris, J. A.; Kim, S. Y.; Brown, W. T.; Cohen, I. L.

2011-01-01

Background: The link between aggression and mental disorders has been the focus of diverse studies in persons with and without intellectual disabilities (ID). Because of discrepancies in the finding of studies in persons with ID to date, and because of differences in research design, instruments used and the population studied, more research is…

BactoGeNIE: a large-scale comparative genome visualization for big displays

PubMed Central

2015-01-01

Background The volume of complete bacterial genome sequence data available to comparative genomics researchers is rapidly increasing. However, visualizations in comparative genomics--which aim to enable analysis tasks across collections of genomes--suffer from visual scalability issues. While large, multi-tiled and high-resolution displays have the potential to address scalability issues, new approaches are needed to take advantage of such environments, in order to enable the effective visual analysis of large genomics datasets. Results In this paper, we present Bacterial Gene Neighborhood Investigation Environment, or BactoGeNIE, a novel and visually scalable design for comparative gene neighborhood analysis on large display environments. We evaluate BactoGeNIE through a case study on close to 700 draft Escherichia coli genomes, and present lessons learned from our design process. Conclusions BactoGeNIE accommodates comparative tasks over substantially larger collections of neighborhoods than existing tools and explicitly addresses visual scalability. Given current trends in data generation, scalable designs of this type may inform visualization design for large-scale comparative research problems in genomics. PMID:26329021

Interpreting the cosmic far-infrared background anisotropies using a gas regulator model

NASA Astrophysics Data System (ADS)

Wu, Hao-Yi; Doré, Olivier; Teyssier, Romain; Serra, Paolo

2018-04-01

Cosmic far-infrared background (CFIRB) is a powerful probe of the history of star formation rate (SFR) and the connection between baryons and dark matter across cosmic time. In this work, we explore to which extent the CFIRB anisotropies can be reproduced by a simple physical framework for galaxy evolution, the gas regulator (bathtub) model. This model is based on continuity equations for gas, stars, and metals, taking into account cosmic gas accretion, star formation, and gas ejection. We model the large-scale galaxy bias and small-scale shot noise self-consistently, and we constrain our model using the CFIRB power spectra measured by Planck. Because of the simplicity of the physical model, the goodness of fit is limited. We compare our model predictions with the observed correlation between CFIRB and gravitational lensing, bolometric infrared luminosity functions, and submillimetre source counts. The strong clustering of CFIRB indicates a large galaxy bias, which corresponds to haloes of mass 1012.5 M⊙ at z = 2, higher than the mass associated with the peak of the star formation efficiency. We also find that the far-infrared luminosities of haloes above 1012 M⊙ are higher than the expectation from the SFR observed in ultraviolet and optical surveys.

Interaction of monopoles, dipoles, and turbulence with a shear flow

NASA Astrophysics Data System (ADS)

Marques Rosas Fernandes, V. H.; Kamp, L. P. J.; van Heijst, G. J. F.; Clercx, H. J. H.

2016-09-01

Direct numerical simulations have been conducted to examine the evolution of eddies in the presence of large-scale shear flows. The numerical experiments consist of initial-value-problems in which monopolar and dipolar vortices as well as driven turbulence are superposed on a plane Couette or Poiseuille flow in a periodic two-dimensional channel. The evolution of the flow has been examined for different shear rates of the background flow and different widths of the channel. Results found for retro-grade and pro-grade monopolar vortices are consistent with those found in the literature. Boundary layer vorticity, however, can significantly modify the straining and erosion of monopolar vortices normally seen for unbounded domains. Dipolar vortices are shown to be much more robust coherent structures in a large-scale shear flow than monopolar eddies. An analytical model for their trajectories, which are determined by self-advection and advection and rotation by the shear flow, is presented. Turbulent kinetic energy is effectively suppressed by the shearing action of the background flow provided that the shear is linear (Couette flow) and of sufficient strength. Nonlinear shear as present in the Poiseuille flow seems to even increase the turbulence strength especially for high shear rates.

Impact of new physics on the EW vacuum stability in a curved spacetime background

NASA Astrophysics Data System (ADS)

Bentivegna, E.; Branchina, V.; Contino, F.; Zappalà, D.

2017-12-01

It has been recently shown that, contrary to an intuitive decoupling argument, the presence of new physics at very large energy scales (say around the Planck scale) can have a strong impact on the electroweak vacuum lifetime. In particular, the vacuum could be totally destabilized. This study was performed in a flat spacetime background, and it is important to extend the analysis to curved spacetime since these are Planckian-physics effects. It is generally expected that under these extreme conditions gravity should totally quench the formation of true vacuum bubbles, thus washing out the destabilizing effect of new physics. In this work we extend the analysis to curved spacetime and show that, although gravity pushes toward stabilization, the destabilizing effect of new physics is still (by far) the dominating one. In order to get model independent results, high energy new physics is parametrized in two different independent ways: as higher order operators in the Higgs field, or introducing new particles with very large masses. The destabilizing effect is observed in both cases, hinting at a general mechanism that does not depend on the parametrization details for new physics, thus maintaining the results obtained from the analysis performed in flat spacetime.

Sterile neutrinos with secret interactions — lasting friendship with cosmology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chu, Xiaoyong; Dasgupta, Basudeb; Kopp, Joachim

Sterile neutrinos with mass ≃1 eV and order 10% mixing with active neutrinos have been proposed as a solution to anomalies in neutrino oscillation data, but are tightly constrained by cosmological limits. It was recently shown that these constraints are avoided if sterile neutrinos couple to a new MeV-scale gauge boson A{sup ′}. However, even this scenario is restricted by structure formation constraints when A{sup ′}-mediated collisional processes lead to efficient active-to-sterile neutrino conversion after neutrinos have decoupled. In view of this, we reevaluate in this paper the viability of sterile neutrinos with such “secret” interactions. We carefully dissect theirmore » evolution in the early Universe, including the various production channels and the expected modifications to large scale structure formation. We argue that there are two regions in parameter space — one at very small A{sup ′} coupling, one at relatively large A{sup ′} coupling — where all constraints from big bang nucleosynthesis (BBN), cosmic microwave background (CMB), and large scale structure (LSS) data are satisfied. Interestingly, the large A{sup ′} coupling region is precisely the region that was previously shown to have potentially important consequences for the small scale structure of dark matter halos if the A{sup ′} boson couples also to the dark matter in the Universe.« less

Recovery of Large Angular Scale CMB Polarization for Instruments Employing Variable-Delay Polarization Modulators

NASA Technical Reports Server (NTRS)

Miller, N. J.; Chuss, D. T.; Marriage, T. A.; Wollack, E. J.; Appel, J. W.; Bennett, C. L.; Eimer, J.; Essinger-Hileman, T.; Fixsen, D. J.; Harrington, K.;

The Weird Side of the Universe: Preferred Axis

NASA Astrophysics Data System (ADS)

Zhao, Wen; Santos, Larissa

In both WMAP and Planck observations on the temperature anisotropy of cosmic microwave background (CMB) radiation a number of large-scale anomalies were discovered in the past years, including the CMB parity asymmetry in the low multipoles. By defining a directional statistics, we find that the CMB parity asymmetry is directional dependent, and the preferred axis is stable, which means that it is independent of the chosen CMB map, the definition of the statistic, or the CMB masks. Meanwhile, we find that this preferred axis strongly aligns with those of the CMB quadrupole, octopole, as well as those of other large-scale observations. In addition, all of them aligns with the CMB kinematic dipole, which hints to the non-cosmological origin of these directional anomalies in cosmological observations.

Constraints on inflation with LSS surveys: features in the primordial power spectrum

NASA Astrophysics Data System (ADS)

Palma, Gonzalo A.; Sapone, Domenico; Sypsas, Spyros

2018-06-01

We analyse the efficiency of future large scale structure surveys to unveil the presence of scale dependent features in the primordial spectrum—resulting from cosmic inflation—imprinted in the distribution of galaxies. Features may appear as a consequence of non-trivial dynamics during cosmic inflation, in which one or more background quantities experienced small but rapid deviations from their characteristic slow-roll evolution. We consider two families of features: localised features and oscillatory extended features. To characterise them we employ various possible templates parametrising their scale dependence and provide forecasts on the constraints on these parametrisations for LSST like surveys. We perform a Fisher matrix analysis for three observables: cosmic microwave background (CMB), galaxy clustering and weak lensing. We find that the combined data set of these observables will be able to limit the presence of features down to levels that are more restrictive than current constraints coming from CMB observations only. In particular, we address the possibility of gaining information on currently known deviations from scale invariance inferred from CMB data, such as the feature appearing at the l ~ 20 multipole (which is the main contribution to the low-l deficit) and another one around l ~ 800.

Ghost dark matter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Furukawa, Tomonori; Yokoyama, Shuichiro; Ichiki, Kiyotomo

2010-05-01

We revisit ghost dark matter, the possibility that ghost condensation may serve as an alternative to dark matter. In particular, we investigate the Friedmann-Robertson-Walker (FRW) background evolution and the large-scale structure (LSS) in the ΛGDM universe, i.e. a late-time universe dominated by a cosmological constant and ghost dark matter. The FRW background of the ΛGDM universe is indistinguishable from that of the standard ΛCDM universe if M∼>1eV, where M is the scale of spontaneous Lorentz breaking. From the LSS we find a stronger bound: M∼>10eV. For smaller M, ghost dark matter would have non-negligible sound speed after the matter-radiation equality,more » and thus the matter power spectrum would significantly differ from observation. These bounds are compatible with the phenomenological upper bound M∼<100GeV known in the literature.« less

Image retrieval by information fusion based on scalable vocabulary tree and robust Hausdorff distance

NASA Astrophysics Data System (ADS)

Che, Chang; Yu, Xiaoyang; Sun, Xiaoming; Yu, Boyang

2017-12-01

In recent years, Scalable Vocabulary Tree (SVT) has been shown to be effective in image retrieval. However, for general images where the foreground is the object to be recognized while the background is cluttered, the performance of the current SVT framework is restricted. In this paper, a new image retrieval framework that incorporates a robust distance metric and information fusion is proposed, which improves the retrieval performance relative to the baseline SVT approach. First, the visual words that represent the background are diminished by using a robust Hausdorff distance between different images. Second, image matching results based on three image signature representations are fused, which enhances the retrieval precision. We conducted intensive experiments on small-scale to large-scale image datasets: Corel-9, Corel-48, and PKU-198, where the proposed Hausdorff metric and information fusion outperforms the state-of-the-art methods by about 13, 15, and 15%, respectively.

Gravitational Lensing Effect on the Two-Point Correlation of Hot Spots in the Cosmic Microwave Background.

PubMed

Takada; Komatsu; Futamase

2000-04-20

We investigate the weak gravitational lensing effect that is due to the large-scale structure of the universe on two-point correlations of local maxima (hot spots) in the two-dimensional sky map of the cosmic microwave background (CMB) anisotropy. According to the Gaussian random statistics, as most inflationary scenarios predict, the hot spots are discretely distributed, with some characteristic angular separations on the last scattering surface that are due to oscillations of the CMB angular power spectrum. The weak lensing then causes pairs of hot spots, which are separated with the characteristic scale, to be observed with various separations. We found that the lensing fairly smooths out the oscillatory features of the two-point correlation function of hot spots. This indicates that the hot spot correlations can be a new statistical tool for measuring the shape and normalization of the power spectrum of matter fluctuations from the lensing signatures.

Power spectrum constraints from spectral distortions in the cosmic microwave background

NASA Technical Reports Server (NTRS)

Hu, Wayne; Scott, Douglas; Silk, Joseph

1994-01-01

Using recent experimental limits on chemical potential distortions from Cosmic Background Explorer (COBE) Far Infrared Astronomy Satellite (FIRAS), and the large lever-arm spanning the damping of sub-Jeans scale fluctuations to the COBE DMR fluctuations, we set a constraint on the slope of the primordial power spectrum n. It is possible to analytically calculate the contribution over the full range of scales and redshifts, correctly taking into account fluctuation growth and damping as well as thermalization processes. Assuming conservatively that mu is less than 1.76 x 10(exp -4), we find that the 95% upper limit on n is only weakly dependent on other cosmological parameters, e.g., n is less than 1.60 (h=0.5) and n is less than 1.63 (h=1.0) for Omega(sub 0) = 1, with marginally weaker constraints for Omega(sub 0) is less than 1 in a flat model with a cosmological constant.

Behavior of a high-temperature superconducting conductor on a round core cable at current ramp rates as high as 67.8 kA s-1 in background fields of up to 19 T

NASA Astrophysics Data System (ADS)

Michael, P. C.; Bromberg, L.; van der Laan, D. C.; Noyes, P.; Weijers, H. W.

2016-04-01

High temperature superconducting (HTS) conductor-on-round-core (CORC®) cables have been developed for use in power transmission systems and large high-field magnets. The use of high-current conductors for large-scale magnets reduces system inductance and limits the peak voltage needed for ramped field operation. A CORC® cable contains a large number of RE-Ba2Cu3O7-δ (RE = rare earth) (REBCO) coated conductors, helically wound in multiple layers on a thin, round former. Large-scale applications, such as fusion and accelerator magnets, require current ramp rates of several kilo-Amperes per second during pulsed operation. This paper presents results that demonstrate the electromagnetic stability of a CORC® cable during transient conditions. Measurements were performed at 4.2 K using a 1.55 m long CORC® cable in background fields of up to 19 T. Repeated current pulses in a background field of 19 T at current ramp rates of up to 67.8 kA s-1 to approximately 90% of the cable’s quench current at that field, did not show any sign of degradation in cable performance due to excessive ac loss or electromagnetic instability. The very high current ramp rates applied during these tests were used to compensate, to the extent possible, the limited cable length accommodated by the test facility, assuming that the measured results could be extrapolated to longer length cables operated at proportionally lower current ramp rates. No shift of the superconducting transition to lower current was measured when the current ramp rate was increased from 25 A s-1 to 67.8 kA s-1. These results demonstrate the viability of CORC® cables for use in low-inductance magnets that operate at moderate to high current ramp rates.

Large tensor non-Gaussianity from axion-gauge field dynamics

NASA Astrophysics Data System (ADS)

Agrawal, Aniket; Fujita, Tomohiro; Komatsu, Eiichiro

2018-05-01

We show that an inflation model in which a spectator axion field is coupled to an S U (2 ) gauge field produces a large three-point function (bispectrum) of primordial gravitational waves, Bh, on the scales relevant to the cosmic microwave background experiments. The amplitude of the bispectrum at the equilateral configuration is characterized by Bh/Ph2=O (10 )×ΩA-1 , where ΩA is a fraction of the energy density in the gauge field and Ph is the power spectrum of gravitational waves produced by the gauge field.

The Uncertainty of Local Background Magnetic Field Orientation in Anisotropic Plasma Turbulence

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gerick, F.; Saur, J.; Papen, M. von, E-mail: felix.gerick@uni-koeln.de

In order to resolve and characterize anisotropy in turbulent plasma flows, a proper estimation of the background magnetic field is crucially important. Various approaches to calculating the background magnetic field, ranging from local to globally averaged fields, are commonly used in the analysis of turbulent data. We investigate how the uncertainty in the orientation of a scale-dependent background magnetic field influences the ability to resolve anisotropy. Therefore, we introduce a quantitative measure, the angle uncertainty, that characterizes the uncertainty of the orientation of the background magnetic field that turbulent structures are exposed to. The angle uncertainty can be used asmore » a condition to estimate the ability to resolve anisotropy with certain accuracy. We apply our description to resolve the spectral anisotropy in fast solar wind data. We show that, if the angle uncertainty grows too large, the power of the turbulent fluctuations is attributed to false local magnetic field angles, which may lead to an incorrect estimation of the spectral indices. In our results, an apparent robustness of the spectral anisotropy to false local magnetic field angles is observed, which can be explained by a stronger increase of power for lower frequencies when the scale of the local magnetic field is increased. The frequency-dependent angle uncertainty is a measure that can be applied to any turbulent system.« less

Cosmology of f(R) gravity in the metric variational approach

NASA Astrophysics Data System (ADS)

Li, Baojiu; Barrow, John D.

2007-04-01

We consider the cosmologies that arise in a subclass of f(R) gravity with f(R)=R+μ2n+2/(-R)n and n∈(-1,0) in the metric (as opposed to the Palatini) variational approach to deriving the gravitational field equations. The calculations of the isotropic and homogeneous cosmological models are undertaken in the Jordan frame and at both the background and the perturbation levels. For the former, we also discuss the connection to the Einstein frame in which the extra degree of freedom in the theory is associated with a scalar field sharing some of the properties of a “chameleon” field. For the latter, we derive the cosmological perturbation equations in general theories of f(R) gravity in covariant form and implement them numerically to calculate the cosmic microwave background (CMB) temperature and matter power spectra of the cosmological model. The CMB power is shown to reduce at low l’s, and the matter power spectrum is almost scale independent at small scales, thus having a similar shape to that in standard general relativity. These are in stark contrast with what was found in the Palatini f(R) gravity, where the CMB power is largely amplified at low l’s and the matter spectrum is strongly scale dependent at small scales. These features make the present model more adaptable than that arising from the Palatini f(R) field equations, and none of the data on background evolution, CMB power spectrum, or matter power spectrum currently rule it out.

Channeling of multikilojoule high-intensity laser beams in an inhomogeneous plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ivancic, S.; Haberberger, D.; Habara, H.

Channeling experiments were performed that demonstrate the transport of high-intensity (>10¹⁸ W/cm²), multikilojoule laser light through a millimeter-sized, inhomogeneous (~300-μm density scale length) laser produced plasma up to overcritical density, which is an important step forward for the fast-ignition concept. The background plasma density and the density depression inside the channel were characterized with a novel optical probe system. The channel progression velocity was measured, which agrees well with theoretical predictions based on large scale particle-in-cell simulations, confirming scaling laws for the required channeling laser energy and laser pulse duration, which are important parameters for future integrated fast-ignition channeling experiments.

Mitigating nonlinearity in full waveform inversion using scaled-Sobolev pre-conditioning

NASA Astrophysics Data System (ADS)

Zuberi, M. AH; Pratt, R. G.

2018-04-01

The Born approximation successfully linearizes seismic full waveform inversion if the background velocity is sufficiently accurate. When the background velocity is not known it can be estimated by using model scale separation methods. A frequently used technique is to separate the spatial scales of the model according to the scattering angles present in the data, by using either first- or second-order terms in the Born series. For example, the well-known `banana-donut' and the `rabbit ear' shaped kernels are, respectively, the first- and second-order Born terms in which at least one of the scattering events is associated with a large angle. Whichever term of the Born series is used, all such methods suffer from errors in the starting velocity model because all terms in the Born series assume that the background Green's function is known. An alternative approach to Born-based scale separation is to work in the model domain, for example, by Gaussian smoothing of the update vectors, or some other approach for separation by model wavenumbers. However such model domain methods are usually based on a strict separation in which only the low-wavenumber updates are retained. This implies that the scattered information in the data is not taken into account. This can lead to the inversion being trapped in a false (local) minimum when sharp features are updated incorrectly. In this study we propose a scaled-Sobolev pre-conditioning (SSP) of the updates to achieve a constrained scale separation in the model domain. The SSP is obtained by introducing a scaled Sobolev inner product (SSIP) into the measure of the gradient of the objective function with respect to the model parameters. This modified measure seeks reductions in the L2 norm of the spatial derivatives of the gradient without changing the objective function. The SSP does not rely on the Born prediction of scale based on scattering angles, and requires negligible extra computational cost per iteration. Synthetic examples from the Marmousi model show that the constrained scale separation using SSP is able to keep the background updates in the zone of attraction of the global minimum, in spite of using a poor starting model in which conventional methods fail.

Intercomparison Project on Parameterizations of Large-Scale Dynamics for Simulations of Tropical Convection

NASA Astrophysics Data System (ADS)

Sobel, A. H.; Wang, S.; Bellon, G.; Sessions, S. L.; Woolnough, S.

2013-12-01

Parameterizations of large-scale dynamics have been developed in the past decade for studying the interaction between tropical convection and large-scale dynamics, based on our physical understanding of the tropical atmosphere. A principal advantage of these methods is that they offer a pathway to attack the key question of what controls large-scale variations of tropical deep convection. These methods have been used with both single column models (SCMs) and cloud-resolving models (CRMs) to study the interaction of deep convection with several kinds of environmental forcings. While much has been learned from these efforts, different groups' efforts are somewhat hard to compare. Different models, different versions of the large-scale parameterization methods, and experimental designs that differ in other ways are used. It is not obvious which choices are consequential to the scientific conclusions drawn and which are not. The methods have matured to the point that there is value in an intercomparison project. In this context, the Global Atmospheric Systems Study - Weak Temperature Gradient (GASS-WTG) project was proposed at the Pan-GASS meeting in September 2012. The weak temperature gradient approximation is one method to parameterize large-scale dynamics, and is used in the project name for historical reasons and simplicity, but another method, the damped gravity wave (DGW) method, will also be used in the project. The goal of the GASS-WTG project is to develop community understanding of the parameterization methods currently in use. Their strengths, weaknesses, and functionality in models with different physics and numerics will be explored in detail, and their utility to improve our understanding of tropical weather and climate phenomena will be further evaluated. This presentation will introduce the intercomparison project, including background, goals, and overview of the proposed experimental design. Interested groups will be invited to join (it will not be too late), and preliminary results will be presented.

Universality classes of fluctuation dynamics in hierarchical complex systems

NASA Astrophysics Data System (ADS)

Macêdo, A. M. S.; González, Iván R. Roa; Salazar, D. S. P.; Vasconcelos, G. L.

2017-03-01

A unified approach is proposed to describe the statistics of the short-time dynamics of multiscale complex systems. The probability density function of the relevant time series (signal) is represented as a statistical superposition of a large time-scale distribution weighted by the distribution of certain internal variables that characterize the slowly changing background. The dynamics of the background is formulated as a hierarchical stochastic model whose form is derived from simple physical constraints, which in turn restrict the dynamics to only two possible classes. The probability distributions of both the signal and the background have simple representations in terms of Meijer G functions. The two universality classes for the background dynamics manifest themselves in the signal distribution as two types of tails: power law and stretched exponential, respectively. A detailed analysis of empirical data from classical turbulence and financial markets shows excellent agreement with the theory.

Topical report on sources and systems for aquatic plant biomass as an energy resource

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goldman, J.C.; Ryther, J.H.; Waaland, R.

1977-10-21

Background information is documented on the mass cultivation of aquatic plants and systems design that is available from the literature and through consultation with active research scientists and engineers. The biology of microalgae, macroalgae, and aquatic angiosperms is discussed in terms of morphology, life history, mode of existence, and ecological significance, as they relate to cultivation. The requirements for growth of these plants, which are outlined in the test, suggest that productivity rates are dependent primarily on the availability of light and nutrients. It is concluded that the systems should be run with an excess of nutrients and with lightmore » as the limiting factor. A historical review of the mass cultivation of aquatic plants describes the techniques used in commercial large-scale operations throughout the world and recent small-scale research efforts. This review presents information on the biomass yields that have been attained to date in various geographical locations with different plant species and culture conditions, emphasizing the contrast between high yields in small-scale operations and lower yields in large-scale operations.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Seljak, Uroš, E-mail: useljak@berkeley.edu

On large scales a nonlinear transformation of matter density field can be viewed as a biased tracer of the density field itself. A nonlinear transformation also modifies the redshift space distortions in the same limit, giving rise to a velocity bias. In models with primordial nongaussianity a nonlinear transformation generates a scale dependent bias on large scales. We derive analytic expressions for the large scale bias, the velocity bias and the redshift space distortion (RSD) parameter β, as well as the scale dependent bias from primordial nongaussianity for a general nonlinear transformation. These biases can be expressed entirely in termsmore » of the one point distribution function (PDF) of the final field and the parameters of the transformation. The analysis shows that one can view the large scale bias different from unity and primordial nongaussianity bias as a consequence of converting higher order correlations in density into 2-point correlations of its nonlinear transform. Our analysis allows one to devise nonlinear transformations with nearly arbitrary bias properties, which can be used to increase the signal in the large scale clustering limit. We apply the results to the ionizing equilibrium model of Lyman-α forest, in which Lyman-α flux F is related to the density perturbation δ via a nonlinear transformation. Velocity bias can be expressed as an average over the Lyman-α flux PDF. At z = 2.4 we predict the velocity bias of -0.1, compared to the observed value of −0.13±0.03. Bias and primordial nongaussianity bias depend on the parameters of the transformation. Measurements of bias can thus be used to constrain these parameters, and for reasonable values of the ionizing background intensity we can match the predictions to observations. Matching to the observed values we predict the ratio of primordial nongaussianity bias to bias to have the opposite sign and lower magnitude than the corresponding values for the highly biased galaxies, but this depends on the model parameters and can also vanish or change the sign.« less

The Cosmology Large Angular Scale Surveyor

NASA Technical Reports Server (NTRS)

Harrington, Kathleen; Marriage, Tobias; Ali, Aamir; Appel, John; Bennett, Charles; Boone, Fletcher; Brewer, Michael; Chan, Manwei; Chuss, David T.; Colazo, Felipe;

Photon correlation study of background suppressed single InGaN nanocolumns

NASA Astrophysics Data System (ADS)

Yamamoto, Takatoshi; Maekawa, Michiru; Imanishi, Yusuke; Ishizawa, Shunsuke; Nakaoka, Toshihiro; Kishino, Katsumi

2016-04-01

We report on a linearly polarized non-classical light emission from a single InGaN/GaN nanocolumn, which is a site-controlled nanostructure allowing for pixel-like large-scale integration. We have developed a shadow mask technique to reduce background emissions arising from nitride deposits around single nanocolumns and defect states of GaN. The signal to background ratio is improved from 0.5:1 to 10:1, which allows for detailed polarization-dependent measurement and photon-correlation measurements. Polarization-dependent measurements show that linearly polarized emissions arise from excitonic recombination involving a heavy-hole-like electronic state, corresponding to the bulk exciton of an in-plane polarized A exciton. The second-order coherence function at time zero g (2)(0) is 0.52 at 20 K without background correction. This value is explained in terms of a statistical mixture of a single-photon emission with residual weak background emissions, as well as efficient carrier injection from other localized states.

Cosmic microwave background power asymmetry from non-Gaussian modulation.

PubMed

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.

Measuring spacetime: from the big bang to black holes.

PubMed

Tegmark, Max

2002-05-24

Space is not a boring static stage on which events unfold over time, but a dynamic entity with curvature, fluctuations, and a rich life of its own. Spectacular measurements of the cosmic microwave background, gravitational lensing, type Ia supernovae, large-scale structure, spectra of the Lyman alpha forest, stellar dynamics, and x-ray binaries are probing the properties of spacetime over 22 orders of magnitude in scale. Current measurements are consistent with an infinite flat everlasting universe containing about 30% cold dark matter, 65% dark energy, and at least two distinct populations of black holes.

Primordial perturbations with pre-inflationary bounce

NASA Astrophysics Data System (ADS)

Cai, Yong; Wang, Yu-Tong; Zhao, Jin-Yun; Piao, Yun-Song

2018-05-01

Based on the effective field theory (EFT) of nonsingular cosmologies, we build a stable model, without the ghost and gradient instabilities, of bounce-inflation (inflation is preceded by a cosmological bounce). We perform a full simulation for the evolution of scalar perturbation, and find that the perturbation spectrum has a large-scale suppression (as expected), which is consistent with the power deficit of the cosmic microwave background (CMB) TT-spectrum at low multipoles, but unexpectedly, it also shows itself one marked lower valley. The depth of valley is relevant with the physics around the bounce scale, which is model-dependent.

Cosmology from Cosmic Microwave Background and large- scale structure

NASA Astrophysics Data System (ADS)

Xu, Yongzhong

2003-10-01

This dissertation consists of a series of studies, constituting four published papers, involving the Cosmic Microwave Background and the large scale structure, which help constrain Cosmological parameters and potential systematic errors. First, we present a method for comparing and combining maps with different resolutions and beam shapes, and apply it to the Saskatoon, QMAP and COBE/DMR data sets. Although the Saskatoon and QMAP maps detect signal at the 21σ and 40σ, levels, respectively, their difference is consistent with pure noise, placing strong limits on possible systematic errors. In particular, we obtain quantitative upper limits on relative calibration and pointing errors. Splitting the combined data by frequency shows similar consistency between the Ka- and Q-bands, placing limits on foreground contamination. The visual agreement between the maps is equally striking. Our combined QMAP+Saskatoon map, nicknamed QMASK, is publicly available at www.hep.upenn.edu/˜xuyz/qmask.html together with its 6495 x 6495 noise covariance matrix. This thoroughly tested data set covers a large enough area (648 square degrees—at the time, the largest degree-scale map available) to allow a statistical comparison with LOBE/DMR, showing good agreement. By band-pass-filtering the QMAP and Saskatoon maps, we are also able to spatially compare them scale-by-scale to check for beam- and pointing-related systematic errors. Using the QMASK map, we then measure the cosmic microwave background (CMB) power spectrum on angular scales ℓ ˜ 30 200 (1° 6°), and we test it for non-Gaussianity using morphological statistics known as Minkowski functionals. We conclude that the QMASK map is neither a very typical nor a very exceptional realization of a Gaussian random field. At least about 20% of the 1000 Gaussian Monte Carlo maps differ more than the QMASK map from the mean morphological parameters of the Gaussian fields. Finally, we compute the real-space power spectrum and the redshift-space distortions of galaxies in the 2dF 100k galaxy redshift survey using pseudo-Karhunen-Loève eigenmodes and the stochastic bias formalism. Our results agree well with those published by the 2dFGRS team, and have the added advantage of producing easy-to-interpret uncorrelated minimum-variance measurements of the galaxy- galaxy, galaxy-velocity and velocity-velocity power spectra in 27 k-bands, with narrow and well-behaved window functions in the range 0.01 h /Mpc < k < 0.8 h/Mpc. We find no significant detection of baryonic wiggles. We measure the galaxy-matter correlation coefficient r > 0.4 and the redshift-distortion parameter β = 0.49 ± 0.16 for r = 1.

Jordan: Background and U.S. Relations

DTIC Science & Technology

2012-10-03

unemployment , high underemployment, and a large fiscal deficit. Small scale protests in Jordan have become a regular occurrence, not only in the...attempted to appear responsive to calls for change by replacing ministers,1 amending the constitution and electoral law, and raising public sector ...estate sectors are dominated by families of Palestinian origin who have an economic stake in the current order. Other former Palestinian refugees have

Inner space/outer space - The interface between cosmology and particle physics

NASA Astrophysics Data System (ADS)

Kolb, Edward W.; Turner, Michael S.; Lindley, David; Olive, Keith; Seckel, David

A collection of papers covering the synthesis between particle physics and cosmology is presented. The general topics addressed include: standard models of particle physics and cosmology; microwave background radiation; origin and evolution of large-scale structure; inflation; massive magnetic monopoles; supersymmetry, supergravity, and quantum gravity; cosmological constraints on particle physics; Kaluza-Klein cosmology; and future directions and connections in particle physics and cosmology.

Directing the Cooperative Extension Service. Selected Papers Presented at the National Cooperative Extension Administrative Seminar (7th, Madison, Wisconsin, April 30-May 4, 1962).

ERIC Educational Resources Information Center

Clark, Robert C., Ed.; Ralston, N. P., Ed.

The book provides administrators and students of administration with a background of extension programs of the past, the principles of large scale organization, and staff role in attaining extension goals. In Part 1, Changing Goals of the Cooperative Extension Service, C. M. Ferguson, Professor, University of Wisconsin, speaks on "Changing…

Search for Electron Neutrino Appearance at the Δm2˜1eV2 Scale

NASA Astrophysics Data System (ADS)

Aguilar-Arevalo, A. A.; Bazarko, A. O.; Brice, S. J.; Brown, B. C.; Bugel, L.; Cao, J.; Coney, L.; Conrad, J. M.; Cox, D. C.; Curioni, A.; Djurcic, Z.; Finley, D. A.; Fleming, B. T.; Ford, R.; Garcia, F. G.; Garvey, G. T.; Green, C.; Green, J. A.; Hart, T. L.; Hawker, E.; Imlay, R.; Johnson, R. A.; Kasper, P.; Katori, T.; Kobilarcik, T.; Kourbanis, I.; Koutsoliotas, S.; Laird, E. M.; Link, J. M.; Liu, Y.; Liu, Y.; Louis, W. C.; Mahn, K. B. M.; Marsh, W.; Martin, P. S.; McGregor, G.; Metcalf, W.; Meyers, P. D.; Mills, F.; Mills, G. B.; Monroe, J.; Moore, C. D.; Nelson, R. H.; Nienaber, P.; Ouedraogo, S.; Patterson, R. B.; Perevalov, D.; Polly, C. C.; Prebys, E.; Raaf, J. L.; Ray, H.; Roe, B. P.; Russell, A. D.; Sandberg, V.; Schirato, R.; Schmitz, D.; Shaevitz, M. H.; Shoemaker, F. C.; Smith, D.; Sorel, M.; Spentzouris, P.; Stancu, I.; Stefanski, R. J.; Sung, M.; Tanaka, H. A.; Tayloe, R.; Tzanov, M.; van de Water, R.; Wascko, M. O.; White, D. H.; Wilking, M. J.; Yang, H. J.; Zeller, G. P.; Zimmerman, E. D.

2007-06-01

The MiniBooNE Collaboration reports first results of a search for νe appearance in a νμ beam. With two largely independent analyses, we observe no significant excess of events above the background for reconstructed neutrino energies above 475 MeV. The data are consistent with no oscillations within a two-neutrino appearance-only oscillation model.

The Undiscovered World Cosmology from WMAP

NASA Technical Reports Server (NTRS)

Bennett, Charles

2004-01-01

The first findings from a year of WMAP satellite operations provide a detailed full sky map of the cosmic microwave background radiation. The observed temperature anisotropy, combined with the associated polarization information, encodes a wealth of cosmological information. The results have implications for the history, content, and evolution of the universe, and its large scale properties. These and other aspects of the mission will be discussed.

The Undiscovered World: Cosmology from WMAP

NASA Technical Reports Server (NTRS)

Bennett, Charles

2004-01-01

The first findings from a year of WMAP satellite operations provide a detailed full sky map of the cosmic microwave background radiation. The observed temperature anisotropy, combined with the associated polarization information, encodes a wealth of cosmological information. The results have implications for the history, content, and evolution of the universe, and its large scale properties. These and other aspects of the mission will be discussed.

The Effects of American Sign Language as an Assessment Accommodation for Students Who Are Deaf or Hard of Hearing

ERIC Educational Resources Information Center

Cawthon, Stephanie W.; Winton, Samantha M.; Garberoglio, Carrie Lou; Gobble, Mark E.

2011-01-01

Students who are deaf or hard of hearing (SDHH) often need accommodations to participate in large-scale standardized assessments. One way to bridge the gap between the language of the test (English) and a student's linguistic background (often including American Sign Language [ASL]) is to present test items in ASL. The specific aim of this project…

Capabilities for Learning to Read: An Investigation of Social and Economic Effects for Grade 6 Learners in Southern and East Africa

ERIC Educational Resources Information Center

Smith, Michele; Barrett, Angeline M.

2011-01-01

This paper considers what multilevel modelling approaches to analysing large scale cross-national surveys of education quality can tell us about the capabilities that support primary school children in learning to read. The impact of pupil background characteristics on achievement in reading towards the end of the primary cycle in sub-Saharan…

MHD Instability and Turbulence in the Tachocline

NASA Technical Reports Server (NTRS)

Werne, Joe; Wagner, William J. (Technical Monitor)

2003-01-01

The focus of this project was to study the physical processes that govern tachocline dynamics and structure. Specific features explored included stratification, shear, waves, and toroidal and poloidal background fields. In order to address recent theoretical work on anisotropic mixing and dynamics in the tachocline, we were particularly interested in such anisotropic mixing for the specific tachocline processes studied. Transition to turbulence often shapes the largest-scale features that appear spontaneously in a flow during the development of turbulence. The resulting large-scale straining field can control the subsequent dynamics; therefore, anticipation of the large-scale straining field that results for individual realizations of the transition to turbulence can be important for subsequent dynamics, flow morphology, and transport characteristics. As a result, we paid particular attention to the development of turbulence in the stratified and sheared environment of the tachocline. This is complicated by the fact that the linearly stability of sheared MHD flows is non-self-adjoint, implying that normal asymptotic linear stability theory may not be relevant.

Large-scale assembly bias of dark matter halos

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lazeyras, Titouan; Musso, Marcello; Schmidt, Fabian, E-mail: titouan@mpa-garching.mpg.de, E-mail: mmusso@sas.upenn.edu, E-mail: fabians@mpa-garching.mpg.de

We present precise measurements of the assembly bias of dark matter halos, i.e. the dependence of halo bias on other properties than the mass, using curved 'separate universe' N-body simulations which effectively incorporate an infinite-wavelength matter overdensity into the background density. This method measures the LIMD (local-in-matter-density) bias parameters b {sub n} in the large-scale limit. We focus on the dependence of the first two Eulerian biases b {sup E} {sup {sub 1}} and b {sup E} {sup {sub 2}} on four halo properties: the concentration, spin, mass accretion rate, and ellipticity. We quantitatively compare our results with previous worksmore » in which assembly bias was measured on fairly small scales. Despite this difference, our findings are in good agreement with previous results. We also look at the joint dependence of bias on two halo properties in addition to the mass. Finally, using the excursion set peaks model, we attempt to shed new insights on how assembly bias arises in this analytical model.« less

Goldstone models of modified gravity

NASA Astrophysics Data System (ADS)

Brax, Philippe; Valageas, Patrick

2017-02-01

We investigate scalar-tensor theories where matter couples to the scalar field via a kinetically dependent conformal coupling. These models can be seen as the low-energy description of invariant field theories under a global Abelian symmetry. The scalar field is then identified with the Goldstone mode of the broken symmetry. It turns out that the properties of these models are very similar to the ones of ultralocal theories where the scalar-field value is directly determined by the local matter density. This leads to a complete screening of the fifth force in the Solar System and between compact objects, through the ultralocal screening mechanism. On the other hand, the fifth force can have large effects in extended structures with large-scale density gradients, such as galactic halos. Interestingly, it can either amplify or damp Newtonian gravity, depending on the model parameters. We also study the background cosmology and the linear cosmological perturbations. The background cosmology is hardly different from its Λ -CDM counterpart while cosmological perturbations crucially depend on whether the coupling function is convex or concave. For concave functions, growth is hindered by the repulsiveness of the fifth force while it is enhanced in the convex case. In both cases, the departures from the Λ -CDM cosmology increase on smaller scales and peak for galactic structures. For concave functions, the formation of structure is largely altered below some characteristic mass, as smaller structures are delayed and would form later through fragmentation, as in some warm dark matter scenarios. For convex models, small structures form more easily than in the Λ -CDM scenario. This could lead to an over-abundance of small clumps. We use a thermodynamic analysis and show that although convex models have a phase transition between homogeneous and inhomogeneous phases, on cosmological scales the system does not enter the inhomogeneous phase. On the other hand, for galactic halos, the coexistence of small and large substructures in their outer regions could lead to observational signatures of these models.

Evolution of cosmic string networks

NASA Technical Reports Server (NTRS)

Albrecht, Andreas; Turok, Neil

1989-01-01

A discussion of the evolution and observable consequences of a network of cosmic strings is given. A simple model for the evolution of the string network is presented, and related to the statistical mechanics of string networks. The model predicts the long string density throughout the history of the universe from a single parameter, which researchers calculate in radiation era simulations. The statistical mechanics arguments indicate a particular thermal form for the spectrum of loops chopped off the network. Detailed numerical simulations of string networks in expanding backgrounds are performed to test the model. Consequences for large scale structure, the microwave and gravity wave backgrounds, nucleosynthesis and gravitational lensing are calculated.

Large-angle correlations in the cosmic microwave background

NASA Astrophysics Data System (ADS)

Efstathiou, George; Ma, Yin-Zhe; Hanson, Duncan

2010-10-01

It has been argued recently by Copi et al. 2009 that the lack of large angular correlations of the CMB temperature field provides strong evidence against the standard, statistically isotropic, inflationary Lambda cold dark matter (ΛCDM) cosmology. We compare various estimators of the temperature correlation function showing how they depend on assumptions of statistical isotropy and how they perform on the Wilkinson Microwave Anisotropy Probe (WMAP) 5-yr Internal Linear Combination (ILC) maps with and without a sky cut. We show that the low multipole harmonics that determine the large-scale features of the temperature correlation function can be reconstructed accurately from the data that lie outside the sky cuts. The reconstructions are only weakly dependent on the assumed statistical properties of the temperature field. The temperature correlation functions computed from these reconstructions are in good agreement with those computed from the ILC map over the whole sky. We conclude that the large-scale angular correlation function for our realization of the sky is well determined. A Bayesian analysis of the large-scale correlations is presented, which shows that the data cannot exclude the standard ΛCDM model. We discuss the differences between our results and those of Copi et al. Either there exists a violation of statistical isotropy as claimed by Copi et al., or these authors have overestimated the significance of the discrepancy because of a posteriori choices of estimator, statistic and sky cut.

How cosmic microwave background correlations at large angles relate to mass autocorrelations in space

NASA Technical Reports Server (NTRS)

Blumenthal, George R.; Johnston, Kathryn V.

1994-01-01

The Sachs-Wolfe effect is known to produce large angular scale fluctuations in the cosmic microwave background radiation (CMBR) due to gravitational potential fluctuations. We show how the angular correlation function of the CMBR can be expressed explicitly in terms of the mass autocorrelation function xi(r) in the universe. We derive analytic expressions for the angular correlation function and its multipole moments in terms of integrals over xi(r) or its second moment, J(sub 3)(r), which does not need to satisfy the sort of integral constraint that xi(r) must. We derive similar expressions for bulk flow velocity in terms of xi and J(sub 3). One interesting result that emerges directly from this analysis is that, for all angles theta, there is a substantial contribution to the correlation function from a wide range of distance r and that radial shape of this contribution does not vary greatly with angle.

The X-ray emission mechanism of large scale powerful quasar jets: Fermi rules out IC/CMB for 3C 273.

NASA Astrophysics Data System (ADS)

Georganopoulos, Markos; Meyer, Eileen T.

2013-12-01

The process responsible for the Chandra-detected X-ray emission from the large-scale jets of powerful quasars is not clear yet. The two main models are inverse Compton scattering off the cosmic microwave background photons (IC/CMB) and synchrotron emission from a population of electrons separate from those producing the radio-IR emission. These two models imply radically different conditions in the large scale jet in terms of jet speed, kinetic power, and maximum energy of the particle acceleration mechanism, with important implications for the impact of the jet on the larger-scale environment. Georganopoulos et al. (2006) proposed a diagnostic based on a fundamental difference between these two models: the production of synchrotron X-rays requires multi-TeV electrons, while the EC/CMB model requires a cutoff in the electron energy distribution below TeV energies. This has significant implications for the γ-ray emission predicted by these two models. Here we present new Fermi observations that put an upper limit on the gamma-ray flux from the large-scale jet of 3C 273 that clearly violates the flux expected from the IC/CMB X-ray interpretation found by extrapolation of the UV to X-ray spectrum of knot A, thus ruling out the IC/CMB interpretation entirely for this source. Further, the upper limit from Fermi puts a limit on the Doppler beaming factor of at least δ <9, assuming equipartition fields, and possibly as low as δ <5 assuming no major deceleration of the jet from knots A through D1.

ZEPLIN-III direct dark matter search : final results and measurements in support of next generation instruments

NASA Astrophysics Data System (ADS)

Reichhart, Lea

2013-12-01

Astrophysical observations give convincing evidence for a vast non-baryonic component, the so-called dark matter, accounting for over 20% of the overall content of our Universe. Direct dark matter search experiments explore the possibility of interactions of these dark matter particles with ordinary baryonic matter via elastic scattering resulting in single nuclear recoils. The ZEPLIN-III detector operated on the basis of a dualphase (liquid/gas) xenon target, recording events in two separate response channels { scintillation and ionisation. These allow discrimination between electron recoils (from background radiation) and the signal expected from Weakly Interacting Massive Particle (WIMP) elastic scatters. Following a productive first exposure, the detector was upgraded with a new array of ultra-low background photomultiplier tubes, reducing the electron recoil background by over an order of magnitude. A second major upgrade to the detector was the incorporation of a tonne-scale active veto detector system, surrounding the WIMP target. Calibration and science data taken in coincidence with ZEPLIN-III showed rejection of up to 30% of the dominant electron recoil background and over 60% of neutron induced nuclear recoils. Data taking for the second science run finished in May 2011 with a total accrued raw fiducial exposure of 1,344 kg days. With this extensive data set, from over 300 days of run time, a limit on the spin-independent WIMP-nucleon cross-section of 4.8 10-8 pb near 50 GeV/c2 WIMP mass with 90% confidence was set. This result combined with the first science run of ZEPLIN-III excludes the scalar cross-section above 3.9 10-8 pb. Studying the background data taken by the veto detector allowed a calculation of the neutron yield induced by high energy cosmic-ray muons in lead of (5.8 0.2) 10-3 neutrons/muon/(g/cm2) for a mean muon energy of 260 GeV. Measurements of this kind are of great importance for large scale direct dark matter search experiments and future rare event searches in general. Finally, this work includes a comprehensive measurement of the energy dependent quenching factor for low energy nuclear recoils in a plastic scintillator, such as from the ZEPLIN-III veto detector, increasing accuracy for future simulation packages featuring large scale plastic scintillator detector systems.

Large Scale Eocene Ocean Circulation Transition Could Help Antarctic Glaciation.

NASA Astrophysics Data System (ADS)

Baatsen, M.

2016-12-01

The global climate underwent major changes going from the Eocene into the Oligocene, including the formation of a continental-scale Antarctic ice sheet. In addition to a gradual drawdown of CO2 since the Early Eocene, the changing background geography of the earth may also have played a crucial role in setting the background oceanic circulation pattern favorable to ice growth. On the other hand, the ocean circulation may have changed only after the ice sheet started growing, with a similar climatic imprint. It is, therefore, still under debate what the primary forcing or trigger of this transition was. Using an ocean general circulation model (POP) and two different geography reconstruc-tions for the middle-late Eocene, we find two distinctly different patterns of the oceanic circulation to be possible under the same forcing. The first one features deep-water formation and warmer SSTs in the Southern Pacific while in the second, deep water forms in the North Pacific Ocean and Southern Ocean SSTs are colder. The presence of a double equilibrium shows that the ocean circulation was highly susceptible to large scale transitions during the middle-late Eocene. Additionally, changes in benthic oxygen and Neodymium isotopes depict significant changes during the same period. We suggest that a transition in the global meridional overturing circulation can explain the observed changes and preconditions the global climate for the two-step transition into an Icehouse state at the Eocene-Oligocene boundary.

Delensing CMB polarization with external datasets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, Kendrick M.; Hanson, Duncan; LoVerde, Marilena

2012-06-01

One of the primary scientific targets of current and future CMB polarization experiments is the search for a stochastic background of gravity waves in the early universe. As instrumental sensitivity improves, the limiting factor will eventually be B-mode power generated by gravitational lensing, which can be removed through use of so-called ''delensing'' algorithms. We forecast prospects for delensing using lensing maps which are obtained externally to CMB polarization: either from large-scale structure observations, or from high-resolution maps of CMB temperature. We conclude that the forecasts in either case are not encouraging, and that significantly delensing large-scale CMB polarization requires high-resolutionmore » polarization maps with sufficient sensitivity to measure the lensing B-mode. We also present a simple formalism for including delensing in CMB forecasts which is computationally fast and agrees well with Monte Carlos.« less

Intrinsic uncertainty on the nature of dark energy

NASA Astrophysics Data System (ADS)

Valkenburg, Wessel; Kunz, Martin; Marra, Valerio

2013-12-01

We argue that there is an intrinsic noise on measurements of the equation of state parameter w = p/ρ from large-scale structure around us. The presence of the large-scale structure leads to an ambiguity in the definition of the background universe and thus there is a maximal precision with which we can determine the equation of state of dark energy. To study the uncertainty due to local structure, we model density perturbations stemming from a standard inflationary power spectrum by means of the exact Lemaître-Tolman-Bondi solution of Einstein’s equation, and show that the usual distribution of matter inhomogeneities in a ΛCDM cosmology causes a variation of w - as inferred from distance measures - of several percent. As we observe only one universe, or equivalently because of the cosmic variance, this uncertainty is systematic in nature.

Preliminary Evidence for a Virial Shock around the Coma Galaxy Cluster

NASA Astrophysics Data System (ADS)

Keshet, Uri; Kushnir, Doron; Loeb, Abraham; Waxman, Eli

2017-08-01

Galaxy clusters, the largest gravitationally bound objects in the universe, are thought to grow by accreting mass from their surroundings through large-scale virial shocks. Due to electron acceleration in such a shock, it should appear as a γ-ray, hard X-ray, and radio ring, elongated toward the large-scale filaments feeding the cluster, coincident with a cutoff in the thermal Sunyaev-Zel’dovich (SZ) signal. However, no such signature was found until now, and the very existence of cluster virial shocks has remained a theory. We find preliminary evidence for a large γ-ray ring of ˜ 5 {Mpc} minor axis around the Coma cluster, elongated toward the large-scale filament connecting Coma and Abell 1367, detected at the nominal 2.7σ confidence level (5.1σ using control signal simulations). The γ-ray ring correlates both with a synchrotron signal and with the SZ cutoff, but not with Galactic tracers. The γ-ray and radio signatures agree with analytic and numerical predictions if the shock deposits ˜ 1 % of the thermal energy in relativistic electrons over a Hubble time and ˜ 1 % in magnetic fields. The implied inverse Compton and synchrotron cumulative emission from similar shocks can contribute significantly to the diffuse extragalactic γ-ray and low-frequency radio backgrounds. Our results, if confirmed, reveal the prolate structure of the hot gas in Coma, the feeding pattern of the cluster, and properties of the surrounding large-scale voids and filaments. The anticipated detection of such shocks around other clusters would provide a powerful new cosmological probe.

Background-Source Cosmic-Photon Elevation Scaling and Cosmic-Neutron/Photon Date Scaling in MCNP6

NASA Astrophysics Data System (ADS)

Tutt, J.; Anderson, C.; McKinney, G.

Cosmic neutron and photon fluxes are known to scale exponentially with elevation. Consequently, cosmic neutron elevation scaling was implemented for use with the background-source option shortly after its introduction into MCNP6, whereby the neutron flux weight factor was adjusted by the elevation scaling factor when the user-specified elevation differed from the selected background.dat grid-point elevation. At the same time, an elevation scaling factor was suggested for the cosmic photon flux, however, cosmic photon elevation scaling is complicated by the fact that the photon background consists of two components: cosmic and terrestrial. Previous versions of the background.dat file did not provide any way to separate these components. With Rel. 4 of this file in 2015, two new columns were added that provide the energy grid and differential cosmic photon flux separately from the total photon flux. Here we show that the cosmic photon flux component can now be scaled independently and combined with the terrestrial component to form the total photon flux at a user-specified elevation in MCNP6. Cosmic background fluxes also scale with the solar cycle due to solar modulation. This modulation has been shown to be nearly sinusoidal over time, with an inverse effect - increased modulation leads to a decrease in cosmic fluxes. This effect was initially included with the cosmic source option in MCNP6 and has now been extended for use with the background source option when: (1) the date is specified in the background.dat file, and (2) when the user specifies a date on the source definition card. A description of the cosmic-neutron/photon date scaling feature will be presented along with scaling results for past and future date extrapolations.

Pair-barcode high-throughput sequencing for large-scale multiplexed sample analysis

PubMed Central

2012-01-01

Background The multiplexing becomes the major limitation of the next-generation sequencing (NGS) in application to low complexity samples. Physical space segregation allows limited multiplexing, while the existing barcode approach only permits simultaneously analysis of up to several dozen samples. Results Here we introduce pair-barcode sequencing (PBS), an economic and flexible barcoding technique that permits parallel analysis of large-scale multiplexed samples. In two pilot runs using SOLiD sequencer (Applied Biosystems Inc.), 32 independent pair-barcoded miRNA libraries were simultaneously discovered by the combination of 4 unique forward barcodes and 8 unique reverse barcodes. Over 174,000,000 reads were generated and about 64% of them are assigned to both of the barcodes. After mapping all reads to pre-miRNAs in miRBase, different miRNA expression patterns are captured from the two clinical groups. The strong correlation using different barcode pairs and the high consistency of miRNA expression in two independent runs demonstrates that PBS approach is valid. Conclusions By employing PBS approach in NGS, large-scale multiplexed pooled samples could be practically analyzed in parallel so that high-throughput sequencing economically meets the requirements of samples which are low sequencing throughput demand. PMID:22276739

Probing features in the primordial perturbation spectrum with large-scale structure data

NASA Astrophysics Data System (ADS)

L'Huillier, Benjamin; Shafieloo, Arman; Hazra, Dhiraj Kumar; Smoot, George F.; Starobinsky, Alexei A.

2018-06-01

The form of the primordial power spectrum (PPS) of cosmological scalar (matter density) perturbations is not yet constrained satisfactorily in spite of the tremendous amount of information from the Cosmic Microwave Background (CMB) data. While a smooth power-law-like form of the PPS is consistent with the CMB data, some PPSs with small non-smooth features at large scales can also fit the CMB temperature and polarization data with similar statistical evidence. Future CMB surveys cannot help distinguish all such models due to the cosmic variance at large angular scales. In this paper, we study how well we can differentiate between such featured forms of the PPS not otherwise distinguishable using CMB data. We ran 15 N-body DESI-like simulations of these models to explore this approach. Showing that statistics such as the halo mass function and the two-point correlation function are not able to distinguish these models in a DESI-like survey, we advocate to avoid reducing the dimensionality of the problem by demonstrating that the use of a simple three-dimensional count-in-cell density field can be much more effective for the purpose of model distinction.

MRMPROBS: a data assessment and metabolite identification tool for large-scale multiple reaction monitoring based widely targeted metabolomics.

PubMed

Tsugawa, Hiroshi; Arita, Masanori; Kanazawa, Mitsuhiro; Ogiwara, Atsushi; Bamba, Takeshi; Fukusaki, Eiichiro

2013-05-21

We developed a new software program, MRMPROBS, for widely targeted metabolomics by using the large-scale multiple reaction monitoring (MRM) mode. The strategy became increasingly popular for the simultaneous analysis of up to several hundred metabolites at high sensitivity, selectivity, and quantitative capability. However, the traditional method of assessing measured metabolomics data without probabilistic criteria is not only time-consuming but is often subjective and makeshift work. Our program overcomes these problems by detecting and identifying metabolites automatically, by separating isomeric metabolites, and by removing background noise using a probabilistic score defined as the odds ratio from an optimized multivariate logistic regression model. Our software program also provides a user-friendly graphical interface to curate and organize data matrices and to apply principal component analyses and statistical tests. For a demonstration, we conducted a widely targeted metabolome analysis (152 metabolites) of propagating Saccharomyces cerevisiae measured at 15 time points by gas and liquid chromatography coupled to triple quadrupole mass spectrometry. MRMPROBS is a useful and practical tool for the assessment of large-scale MRM data available to any instrument or any experimental condition.

Single field double inflation and primordial black holes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kannike, K.; Marzola, L.; Raidal, M.

Within the framework of scalar-tensor theories, we study the conditions that allow single field inflation dynamics on small cosmological scales to significantly differ from that of the large scales probed by the observations of cosmic microwave background. The resulting single field double inflation scenario is characterised by two consequent inflation eras, usually separated by a period where the slow-roll approximation fails. At large field values the dynamics of the inflaton is dominated by the interplay between its non-minimal coupling to gravity and the radiative corrections to the inflaton self-coupling. For small field values the potential is, instead, dominated by amore » polynomial that results in a hilltop inflation. Without relying on the slow-roll approximation, which is invalidated by the appearance of the intermediate stage, we propose a concrete model that matches the current measurements of inflationary observables and employs the freedom granted by the framework on small cosmological scales to give rise to a sizeable population of primordial black holes generated by large curvature fluctuations. We find that these features generally require a potential with a local minimum. We show that the associated primordial black hole mass function is only approximately lognormal.« less

RECOVERY OF LARGE ANGULAR SCALE CMB POLARIZATION FOR INSTRUMENTS EMPLOYING VARIABLE-DELAY POLARIZATION MODULATORS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miller, N. J.; Marriage, T. A.; Appel, J. W.

2016-02-20

Variable-delay Polarization Modulators (VPMs) are currently being implemented in experiments designed to measure the polarization of the cosmic microwave background on large angular scales because of their capability for providing rapid, front-end polarization modulation and control over systematic errors. Despite the advantages provided by the VPM, it is important to identify and mitigate any time-varying effects that leak into the synchronously modulated component of the signal. In this paper, the effect of emission from a 300 K VPM on the system performance is considered and addressed. Though instrument design can greatly reduce the influence of modulated VPM emission, some residualmore » modulated signal is expected. VPM emission is treated in the presence of rotational misalignments and temperature variation. Simulations of time-ordered data are used to evaluate the effect of these residual errors on the power spectrum. The analysis and modeling in this paper guides experimentalists on the critical aspects of observations using VPMs as front-end modulators. By implementing the characterizations and controls as described, front-end VPM modulation can be very powerful for mitigating 1/f noise in large angular scale polarimetric surveys. None of the systematic errors studied fundamentally limit the detection and characterization of B-modes on large scales for a tensor-to-scalar ratio of r = 0.01. Indeed, r < 0.01 is achievable with commensurately improved characterizations and controls.« less

Cosmological Signatures of a Mirror Twin Higgs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chacko, Zackaria; Curtin, David; Geller, Michael

We explore the cosmological signatures associated with the twin baryons, electrons, photons and neutrinos in the Mirror Twin Higgs framework. We consider a scenario in which the twin baryons constitute a subcomponent of dark matter, and the contribution of the twin photon and neutrinos to dark radiation is suppressed due to late asymmetric reheating, but remains large enough to be detected in future cosmic microwave background (CMB) experiments. We show that this framework can lead to distinctive signals in large scale structure and in the cosmic microwave background. Baryon acoustic oscillations in the mirror sector prior to recombination lead tomore » a suppression of structure on large scales, and leave a residual oscillatory pattern in the matter power spectrum. This pattern depends sensitively on the relative abundances and ionization energies of both twin hydrogen and helium, and is therefore characteristic of this class of models. Although both mirror photons and neutrinos constitute dark radiation in the early universe, their effects on the CMB are distinct. This is because prior to recombination the twin neutrinos free stream, while the twin photons are prevented from free streaming by scattering off twin electrons. In the Mirror Twin Higgs framework the relative contributions of these two species to the energy density in dark radiation is predicted, leading to testable effects in the CMB. These highly distinctive cosmological signatures may allow this class of models to be discovered, and distinguished from more general dark sectors.« less

Customization in Schooling Markets: The Relationship between Curriculum and Pedagogy in a "Pop-Up" Learning Project, and the Epistemic Opportunities Afforded by Students' Interests and Backgrounds

ERIC Educational Resources Information Center

Hayes, Debra

2013-01-01

Schooling markets prioritize the needs of valued "customers". In Australia, this has resulted in a proliferation of learning interventions aimed at attracting and holding students perceived to fall into this category, and managing those who don't. In this paper, I attempt two main tasks: a description of the large-scale processes…

The observable signature of late heating of the Universe during cosmic reionization.

PubMed

Fialkov, Anastasia; Barkana, Rennan; Visbal, Eli

2014-02-13

Models and simulations of the epoch of reionization predict that spectra of the 21-centimetre transition of atomic hydrogen will show a clear fluctuation peak, at a redshift and scale, respectively, that mark the central stage of reionization and the characteristic size of ionized bubbles. This is based on the assumption that the cosmic gas was heated by stellar remnants-particularly X-ray binaries-to temperatures well above the cosmic microwave background at that time (about 30 kelvin). Here we show instead that the hard spectra (that is, spectra with more high-energy photons than low-energy photons) of X-ray binaries make such heating ineffective, resulting in a delayed and spatially uniform heating that modifies the 21-centimetre signature of reionization. Rather than looking for a simple rise and fall of the large-scale fluctuations (peaking at several millikelvin), we must expect a more complex signal also featuring a distinct minimum (at less than a millikelvin) that marks the rise of the cosmic mean gas temperature above the microwave background. Observing this signal, possibly with radio telescopes in operation today, will demonstrate the presence of a cosmic background of hard X-rays at that early time.

Assessing the Impact of Pre-gpm Microwave Precipitation Observations in the Goddard WRF Ensemble Data Assimilation System

NASA Technical Reports Server (NTRS)

Chambon, Philippe; Zhang, Sara Q.; Hou, Arthur Y.; Zupanski, Milija; Cheung, Samson

2013-01-01

The forthcoming Global Precipitation Measurement (GPM) Mission will provide next generation precipitation observations from a constellation of satellites. Since precipitation by nature has large variability and low predictability at cloud-resolving scales, the impact of precipitation data on the skills of mesoscale numerical weather prediction (NWP) is largely affected by the characterization of background and observation errors and the representation of nonlinear cloud/precipitation physics in an NWP data assimilation system. We present a data impact study on the assimilation of precipitation-affected microwave (MW) radiances from a pre-GPM satellite constellation using the Goddard WRF Ensemble Data Assimilation System (Goddard WRF-EDAS). A series of assimilation experiments are carried out in a Weather Research Forecast (WRF) model domain of 9 km resolution in western Europe. Sensitivities to observation error specifications, background error covariance estimated from ensemble forecasts with different ensemble sizes, and MW channel selections are examined through single-observation assimilation experiments. An empirical bias correction for precipitation-affected MW radiances is developed based on the statistics of radiance innovations in rainy areas. The data impact is assessed by full data assimilation cycling experiments for a storm event that occurred in France in September 2010. Results show that the assimilation of MW precipitation observations from a satellite constellation mimicking GPM has a positive impact on the accumulated rain forecasts verified with surface radar rain estimates. The case-study on a convective storm also reveals that the accuracy of ensemble-based background error covariance is limited by sampling errors and model errors such as precipitation displacement and unresolved convective scale instability.

The effect of abrupt climate changes and climate background conditions in Southern Europe during the last glacial

NASA Astrophysics Data System (ADS)

Knorr, Gregor; Martin-Puertas, Celia; Brauer, Achim; Lohmann, Gerrit

2015-04-01

The last glacial period is characterized by abrupt and large temperature shifts in Greenland and the North Atlantic realm. Pollen and sediment data from Lago Grande di Monticchio (MON) have demonstrated a clear imprint of these fluctuations operating at millennial time-scales. Interestingly, basic mean environmental condition changes with respect to temperature and precipitation occurred during MIS4, separating warm and dry conditions during MIS5 from relatively cold and humid conditions within MIS3. This general climate background shift is superposed by distinct millennial-scale variability at MON. Using a fully coupled atmosphere-ocean general circulation model applying boundary conditions at 32 ka BP and pre-industrial conditions as a surrogate for MIS3 and MIS5, we have simulated and analysed characteristic changes in Southern Europe during the last glacial. We find that changes in the mean state at MON are mainly related to a partial shift of the North Atlantic deep water (NADW) convection sites from the Nordic Seas to South of Iceland, the presence of the Fennoscandian ice sheet and lower greenhouse gas concentrations. These background characteristics provide the basis for enhanced zonal moisture transport from the eastern North Atlantic to Middle and Southern Europe. Furthermore, simulations of abrupt climate change scenarios show that a deactivation of the convection sites South of Iceland during MIS3 leads to cooler and dryer conditions at MON. Such temperature and precipitation changes are thought to provide a counter-acting effect on woody vegetation and associated pollen signals at MON. This is in contrast to the impact of abrupt climate perturbation scenarios during MIS5, where no significant precipitation changes are detected. Hence, the simulated changes and underlying mechanisms are largely consistent with the recorded proxy evidence with respect to both, mean state and millennial-scale changes.

The Child-care Food and Activity Practices Questionnaire (CFAPQ): development and first validation steps.

PubMed

Gubbels, Jessica S; Sleddens, Ester Fc; Raaijmakers, Lieke Ch; Gies, Judith M; Kremers, Stef Pj

2016-08-01

To develop and validate a questionnaire to measure food-related and activity-related practices of child-care staff, based on existing, validated parenting practices questionnaires. A selection of items from the Comprehensive Feeding Practices Questionnaire (CFPQ) and the Preschooler Physical Activity Parenting Practices (PPAPP) questionnaire was made to include items most suitable for the child-care setting. The converted questionnaire was pre-tested among child-care staff during cognitive interviews and pilot-tested among a larger sample of child-care staff. Factor analyses with Varimax rotation and internal consistencies were used to examine the scales. Spearman correlations, t tests and ANOVA were used to examine associations between the scales and staff's background characteristics (e.g. years of experience, gender). Child-care centres in the Netherlands. The qualitative pre-test included ten child-care staff members. The quantitative pilot test included 178 child-care staff members. The new questionnaire, the Child-care Food and Activity Practices Questionnaire (CFAPQ), consists of sixty-three items (forty food-related and twenty-three activity-related items), divided over twelve scales (seven food-related and five activity-related scales). The CFAPQ scales are to a large extent similar to the original CFPQ and PPAPP scales. The CFAPQ scales show sufficient internal consistency with Cronbach's α ranging between 0·53 and 0·96, and average corrected item-total correlations within acceptable ranges (0·30-0·89). Several of the scales were significantly associated with child-care staff's background characteristics. Scale psychometrics of the CFAPQ indicate it is a valid questionnaire that assesses child-care staff's practices related to both food and activities.

Applying a framework for assessing the health system challenges to scaling up mHealth in South Africa

PubMed Central

2012-01-01

Background Mobile phone technology has demonstrated the potential to improve health service delivery, but there is little guidance to inform decisions about acquiring and implementing mHealth technology at scale in health systems. Using the case of community-based health services (CBS) in South Africa, we apply a framework to appraise the opportunities and challenges to effective implementation of mHealth at scale in health systems. Methods A qualitative study reviewed the benefits and challenges of mHealth in community-based services in South Africa, through a combination of key informant interviews, site visits to local projects and document reviews. Using a framework adapted from three approaches to reviewing sustainable information and communication technology (ICT), the lessons from local experience and elsewhere formed the basis of a wider consideration of scale up challenges in South Africa. Results Four key system dimensions were identified and assessed: government stewardship and the organisational, technological and financial systems. In South Africa, the opportunities for successful implementation of mHealth include the high prevalence of mobile phones, a supportive policy environment for eHealth, successful use of mHealth for CBS in a number of projects and a well-developed ICT industry. However there are weaknesses in other key health systems areas such as organisational culture and capacity for using health information for management, and the poor availability and use of ICT in primary health care. The technological challenges include the complexity of ensuring interoperability and integration of information systems and securing privacy of information. Finally, there are the challenges of sustainable financing required for large scale use of mobile phone technology in resource limited settings. Conclusion Against a background of a health system with a weak ICT environment and limited implementation capacity, it remains uncertain that the potential benefits of mHealth for CBS would be retained with immediate large-scale implementation. Applying a health systems framework facilitated a systematic appraisal of potential challenges to scaling up mHealth for CBS in South Africa and may be useful for policy and practice decision-making in other low- and middle-income settings. PMID:23126370

The Cosmology Large Angular Scale Surveyor

NASA Astrophysics Data System (ADS)

Harrington, Kathleen; Marriage, Tobias; Ali, Aamir; Appel, John W.; Bennett, Charles L.; Boone, Fletcher; Brewer, Michael; Chan, Manwei; Chuss, David T.; Colazo, Felipe; Dahal, Sumit; Denis, Kevin; Dünner, Rolando; Eimer, Joseph; Essinger-Hileman, Thomas; Fluxa, Pedro; Halpern, Mark; Hilton, Gene; Hinshaw, Gary F.; Hubmayr, Johannes; Iuliano, Jeffrey; Karakla, John; McMahon, Jeff; Miller, Nathan T.; Moseley, Samuel H.; Palma, Gonzalo; Parker, Lucas; Petroff, Matthew; Pradenas, Bastián.; Rostem, Karwan; Sagliocca, Marco; Valle, Deniz; Watts, Duncan; Wollack, Edward; Xu, Zhilei; Zeng, Lingzhen

2016-07-01

The Cosmology Large Angular Scale Surveyor (CLASS) is a four telescope array designed to characterize relic primordial gravitational waves from in ation and the optical depth to reionization through a measurement of the polarized cosmic microwave background (CMB) on the largest angular scales. The frequencies of the four CLASS telescopes, one at 38 GHz, two at 93 GHz, and one dichroic system at 145/217 GHz, are chosen to avoid spectral regions of high atmospheric emission and span the minimum of the polarized Galactic foregrounds: synchrotron emission at lower frequencies and dust emission at higher frequencies. Low-noise transition edge sensor detectors and a rapid front-end polarization modulator provide a unique combination of high sensitivity, stability, and control of systematics. The CLASS site, at 5200 m in the Chilean Atacama desert, allows for daily mapping of up to 70% of the sky and enables the characterization of CMB polarization at the largest angular scales. Using this combination of a broad frequency range, large sky coverage, control over systematics, and high sensitivity, CLASS will observe the reionization and recombination peaks of the CMB E- and B-mode power spectra. CLASS will make a cosmic variance limited measurement of the optical depth to reionization and will measure or place upper limits on the tensor-to-scalar ratio, r, down to a level of 0.01 (95% C.L.).

The Cosmology Large Angular Scale Surveyor (CLASS)

NASA Technical Reports Server (NTRS)

Harrington, Kathleen; Marriange, Tobias; Aamir, Ali; Appel, John W.; Bennett, Charles L.; Boone, Fletcher; Brewer, Michael; Chan, Manwei; Chuss, David T.; Colazo, Felipe;

Rainbow: a tool for large-scale whole-genome sequencing data analysis using cloud computing

PubMed Central

2013-01-01

Background Technical improvements have decreased sequencing costs and, as a result, the size and number of genomic datasets have increased rapidly. Because of the lower cost, large amounts of sequence data are now being produced by small to midsize research groups. Crossbow is a software tool that can detect single nucleotide polymorphisms (SNPs) in whole-genome sequencing (WGS) data from a single subject; however, Crossbow has a number of limitations when applied to multiple subjects from large-scale WGS projects. The data storage and CPU resources that are required for large-scale whole genome sequencing data analyses are too large for many core facilities and individual laboratories to provide. To help meet these challenges, we have developed Rainbow, a cloud-based software package that can assist in the automation of large-scale WGS data analyses. Results Here, we evaluated the performance of Rainbow by analyzing 44 different whole-genome-sequenced subjects. Rainbow has the capacity to process genomic data from more than 500 subjects in two weeks using cloud computing provided by the Amazon Web Service. The time includes the import and export of the data using Amazon Import/Export service. The average cost of processing a single sample in the cloud was less than 120 US dollars. Compared with Crossbow, the main improvements incorporated into Rainbow include the ability: (1) to handle BAM as well as FASTQ input files; (2) to split large sequence files for better load balance downstream; (3) to log the running metrics in data processing and monitoring multiple Amazon Elastic Compute Cloud (EC2) instances; and (4) to merge SOAPsnp outputs for multiple individuals into a single file to facilitate downstream genome-wide association studies. Conclusions Rainbow is a scalable, cost-effective, and open-source tool for large-scale WGS data analysis. For human WGS data sequenced by either the Illumina HiSeq 2000 or HiSeq 2500 platforms, Rainbow can be used straight out of the box. Rainbow is available for third-party implementation and use, and can be downloaded from http://s3.amazonaws.com/jnj_rainbow/index.html. PMID:23802613

Allometric scaling of UK urban emissions: interpretation and implications for air quality management

NASA Astrophysics Data System (ADS)

MacKenzie, Rob; Barnes, Matt; Whyatt, Duncan; Hewitt, Nick

2016-04-01

Allometry uncovers structures and patterns by relating the characteristics of complex systems to a measure of scale. We present an allometric analysis of air quality for UK urban settlements, beginning with emissions and moving on to consider air concentrations. We consider both airshed-average 'urban background' concentrations (cf. those derived from satellites for NO2) and local pollution 'hotspots'. We show that there is a strong and robust scaling (with respect to population) of the non-point-source emissions of the greenhouse gases carbon dioxide and methane, as well as the toxic pollutants nitrogen dioxide, PM2.5, and 1,3-butadiene. The scaling of traffic-related emissions is not simply a reflection of road length, but rather results from the socio-economic patterning of road-use. The recent controversy regarding diesel vehicle emissions is germane to our study but does not affect our overall conclusions. We next develop an hypothesis for the population-scaling of airshed-average air concentrations, with which we demonstrate that, although average air quality is expected to be worse in large urban centres compared to small urban centres, the overall effect is an economy of scale (i.e., large cities reduce the overall burden of emissions compared to the same population spread over many smaller urban settlements). Our hypothesis explains satellite-derived observations of airshed-average urban NO2 concentrations. The theory derived also explains which properties of nature-based solutions (urban greening) can make a significant contribution at city scale, and points to a hitherto unforeseen opportunity to make large cities cleaner than smaller cities in absolute terms with respect to their airshed-average pollutant concentration.

Galaxy formation from annihilation-generated supersonic turbulence in the baryon-symmetric big-bang cosmology and the gamma ray background spectrum

NASA Technical Reports Server (NTRS)

Stecker, F. W.; Puget, J. L.

1972-01-01

Following the big-bang baryon symmetric cosmology of Omnes, the redshift was calculated to be on the order of 500-600. It is show that, at these redshifts, annihilation pressure at the boundaries between regions of matter and antimatter drives large scale supersonic turbulence which can trigger galaxy formation. This picture is consistent with the gamma-ray background observations discussed previously. Gravitational binding of galaxies then occurs at a redshift of about 70, at which time vortical turbulent velocities of about 3 x 10 to the 7th power cm/s lead to angular momenta for galaxies comparable with measured values.

Cosmic Microwave Background Polarization and Inflation

NASA Technical Reports Server (NTRS)

Chuss, David T.

2011-01-01

Measurements of the cosmic microwave background (CMB) offer a means to explore the universe at a very early epoch. Specifically, if the universe went through a brief period of exponential expansion called inflation as current data suggest, gravitational waves from this period would polarize the CMB in a specific pattern. At GSFC, we are currently working towards two experiments that work in concert to measure this polarization pattern in search of evidence for inflation. The Cosmology Large Angular Scale Surveyor (CLASS) will measure the polarization at frequencies between 40 and 150 GHz from the Atacama Desert in Chile. The Primordial Inflation Polarization Explorer (PIPER) is a balloon-borne experiment that will make similar measurements at frequencies between 200 and 600 GHz.

Background-Source Cosmic-Photon Elevation Scaling and Cosmic-Neutron/Photon Date Scaling in MCNP6

DOE PAGES

Tutt, James Robert; Anderson, Casey Alan; McKinney, Gregg Walter

2017-10-26

Here, cosmic neutron and photon fluxes are known to scale exponentially with elevation. Consequently, cosmic neutron elevation scaling was implemented for use with the background-source option shortly after its introduction into MCNP6, whereby the neutron flux weight factor was adjusted by the elevation scaling factor when the user-specified elevation differed from the selected background.dat grid-point elevation. At the same time, an elevation scaling factor was suggested for the cosmic photon flux, however, cosmic photon elevation scaling is complicated by the fact that the photon background consists of two components: cosmic and terrestrial. Previous versions of the background.dat file did notmore » provide any way to separate these components. With Rel. 4 of this file in 2015, two new columns were added that provide the energy grid and differential cosmic photon flux separately from the total photon flux. Here we show that the cosmic photon flux component can now be scaled independently and combined with the terrestrial component to form the total photon flux at a user-specified elevation in MCNP6.« less

Background-Source Cosmic-Photon Elevation Scaling and Cosmic-Neutron/Photon Date Scaling in MCNP6

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tutt, James Robert; Anderson, Casey Alan; McKinney, Gregg Walter

Here, cosmic neutron and photon fluxes are known to scale exponentially with elevation. Consequently, cosmic neutron elevation scaling was implemented for use with the background-source option shortly after its introduction into MCNP6, whereby the neutron flux weight factor was adjusted by the elevation scaling factor when the user-specified elevation differed from the selected background.dat grid-point elevation. At the same time, an elevation scaling factor was suggested for the cosmic photon flux, however, cosmic photon elevation scaling is complicated by the fact that the photon background consists of two components: cosmic and terrestrial. Previous versions of the background.dat file did notmore » provide any way to separate these components. With Rel. 4 of this file in 2015, two new columns were added that provide the energy grid and differential cosmic photon flux separately from the total photon flux. Here we show that the cosmic photon flux component can now be scaled independently and combined with the terrestrial component to form the total photon flux at a user-specified elevation in MCNP6.« less

Morphological filtering and multiresolution fusion for mammographic microcalcification detection

NASA Astrophysics Data System (ADS)

Chen, Lulin; Chen, Chang W.; Parker, Kevin J.

1997-04-01

Mammographic images are often of relatively low contrast and poor sharpness with non-stationary background or clutter and are usually corrupted by noise. In this paper, we propose a new method for microcalcification detection using gray scale morphological filtering followed by multiresolution fusion and present a unified general filtering form called the local operating transformation for whitening filtering and adaptive thresholding. The gray scale morphological filters are used to remove all large areas that are considered as non-stationary background or clutter variations, i.e., to prewhiten images. The multiresolution fusion decision is based on matched filter theory. In addition to the normal matched filter, the Laplacian matched filter which is directly related through the wavelet transforms to multiresolution analysis is exploited for microcalcification feature detection. At the multiresolution fusion stage, the region growing techniques are used in each resolution level. The parent-child relations between resolution levels are adopted to make final detection decision. FROC is computed from test on the Nijmegen database.

Postprocessing Algorithm for Driving Conventional Scanning Tunneling Microscope at Fast Scan Rates.

PubMed

Zhang, Hao; Li, Xianqi; Chen, Yunmei; Park, Jewook; Li, An-Ping; Zhang, X-G

2017-01-01

We present an image postprocessing framework for Scanning Tunneling Microscope (STM) to reduce the strong spurious oscillations and scan line noise at fast scan rates and preserve the features, allowing an order of magnitude increase in the scan rate without upgrading the hardware. The proposed method consists of two steps for large scale images and four steps for atomic scale images. For large scale images, we first apply for each line an image registration method to align the forward and backward scans of the same line. In the second step we apply a "rubber band" model which is solved by a novel Constrained Adaptive and Iterative Filtering Algorithm (CIAFA). The numerical results on measurement from copper(111) surface indicate the processed images are comparable in accuracy to data obtained with a slow scan rate, but are free of the scan drift error commonly seen in slow scan data. For atomic scale images, an additional first step to remove line-by-line strong background fluctuations and a fourth step of replacing the postprocessed image by its ranking map as the final atomic resolution image are required. The resulting image restores the lattice image that is nearly undetectable in the original fast scan data.

Do inertial wave interactions control the rate of energy dissipation of rotating turbulence?

NASA Astrophysics Data System (ADS)

Cortet, Pierre-Philippe; Campagne, Antoine; Machicoane, Nathanael; Gallet, Basile; Moisy, Frederic

2015-11-01

The scaling law of the energy dissipation rate, ɛ ~U3 / L (with U and L the characteristic velocity and lengthscale), is one of the most robust features of fully developed turbulence. How this scaling is affected by a background rotation is still a controversial issue with importance for geo and astrophysical flows. At asymptotically small Rossby numbers Ro = U / ΩL , i.e. in the weakly nonlinear limit, wave-turbulence arguments suggest that ɛ should be reduced by a factor Ro . Such scaling has however never been evidenced directly, neither experimentally nor numerically. We report here direct measurements of the injected power, and therefore of ɛ, in an experiment where a propeller is rotating at a constant rate in a large volume of fluid rotating at Ω. In co-rotation, we find a transition between the wave-turbulence scaling at small Ro and the classical Kolmogorov law at large Ro . The transition between these two regimes is characterized from experiments varying the propeller and tank dimensions. In counter-rotation, the scenario is much richer with the observation of an additional peak of dissipation, similar to the one found in Taylor-Couette experiments.

Searching for signatures of dark matter-dark radiation interaction in observations of large-scale structure

NASA Astrophysics Data System (ADS)

Pan, Zhen; Kaplinghat, Manoj; Knox, Lloyd

2018-05-01

In this paper, we conduct a search in the latest large-scale structure measurements for signatures of the dark matter-dark radiation interaction proposed by Buen-Abad et al. (2015). We show that prior claims of an inference of this interaction at ˜3 σ significance rely on a use of the Sunyaev-Zeldovich cluster mass function that ignores uncertainty in the mass-observable relationship. Including this uncertainty we find that the inferred level of interaction remains consistent with the data, but so does zero interaction; i.e., there is no longer a preference for nonzero interaction. We also point out that inference of the shape and amplitude of the matter power spectrum from Ly α forest measurements is highly inconsistent with the predictions of the Λ CDM model conditioned on Planck cosmic microwave background temperature, polarization, and lensing power spectra, and that the dark matter-dark radiation model can restore that consistency. We also phenomenologically generalize the model of Buen-Abad et al. (2015) to allow for interaction rates with different scalings with temperature, and find that the original scaling is preferred by the data.

Neutrino Mass Bounds from 0{nu}{beta}{beta} Decays and Large Scale Structures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Keum, Y.-Y.; Department of Physics, National Taiwan University, Taipei, Taiwan 10672; Ichiki, K.

2008-05-21

We investigate the way how the total mass sum of neutrinos can be constrained from the neutrinoless double beta decay and cosmological probes with cosmic microwave background (WMAP 3-year results), large scale structures including 2dFGRS and SDSS data sets. First we discuss, in brief, on the current status of neutrino mass bounds from neutrino beta decays and cosmic constrain within the flat {lambda}CMD model. In addition, we explore the interacting neutrino dark-energy model, where the evolution of neutrino masses is determined by quintessence scalar filed, which is responsable for cosmic acceleration today. Assuming the flatness of the universe, the constraintmore » we can derive from the current observation is {sigma}m{sub {nu}}<0.87 eV at the 95% confidence level, which is consistent with {sigma}m{sub {nu}}<0.68 eV in the flat {lambda}CDM model.« less

Exhaustive identification of steady state cycles in large stoichiometric networks

PubMed Central

Wright, Jeremiah; Wagner, Andreas

2008-01-01

Background Identifying cyclic pathways in chemical reaction networks is important, because such cycles may indicate in silico violation of energy conservation, or the existence of feedback in vivo. Unfortunately, our ability to identify cycles in stoichiometric networks, such as signal transduction and genome-scale metabolic networks, has been hampered by the computational complexity of the methods currently used. Results We describe a new algorithm for the identification of cycles in stoichiometric networks, and we compare its performance to two others by exhaustively identifying the cycles contained in the genome-scale metabolic networks of H. pylori, M. barkeri, E. coli, and S. cerevisiae. Our algorithm can substantially decrease both the execution time and maximum memory usage in comparison to the two previous algorithms. Conclusion The algorithm we describe improves our ability to study large, real-world, biochemical reaction networks, although additional methodological improvements are desirable. PMID:18616835

Searching for modified growth patterns with tomographic surveys

NASA Astrophysics Data System (ADS)

Zhao, Gong-Bo; Pogosian, Levon; Silvestri, Alessandra; Zylberberg, Joel

2009-04-01

In alternative theories of gravity, designed to produce cosmic acceleration at the current epoch, the growth of large scale structure can be modified. We study the potential of upcoming and future tomographic surveys such as Dark Energy Survey (DES) and Large Synoptic Survey Telescope (LSST), with the aid of cosmic microwave background (CMB) and supernovae data, to detect departures from the growth of cosmic structure expected within general relativity. We employ parametric forms to quantify the potential time- and scale-dependent variation of the effective gravitational constant and the differences between the two Newtonian potentials. We then apply the Fisher matrix technique to forecast the errors on the modified growth parameters from galaxy clustering, weak lensing, CMB, and their cross correlations across multiple photometric redshift bins. We find that even with conservative assumptions about the data, DES will produce nontrivial constraints on modified growth and that LSST will do significantly better.

Measuring Large-Scale Social Networks with High Resolution

PubMed Central

Stopczynski, Arkadiusz; Sekara, Vedran; Sapiezynski, Piotr; Cuttone, Andrea; Madsen, Mette My; Larsen, Jakob Eg; Lehmann, Sune

2014-01-01

This paper describes the deployment of a large-scale study designed to measure human interactions across a variety of communication channels, with high temporal resolution and spanning multiple years—the Copenhagen Networks Study. Specifically, we collect data on face-to-face interactions, telecommunication, social networks, location, and background information (personality, demographics, health, politics) for a densely connected population of 1 000 individuals, using state-of-the-art smartphones as social sensors. Here we provide an overview of the related work and describe the motivation and research agenda driving the study. Additionally, the paper details the data-types measured, and the technical infrastructure in terms of both backend and phone software, as well as an outline of the deployment procedures. We document the participant privacy procedures and their underlying principles. The paper is concluded with early results from data analysis, illustrating the importance of multi-channel high-resolution approach to data collection. PMID:24770359

Large-scale galactic motions: test of the Dipole Repeller model with the RFGC galaxies data

NASA Astrophysics Data System (ADS)

Parnovsky, S.

2017-06-01

The paper "The Dipole Repeller" in Nature Astronomy by Hoffman et al. state that the local large-scale galactic flow is dominated by a single attractor - associated with the Shapley Concentration - and a single previously unidentified repeller. We check this hypothesis using the data for 1459 galaxies from RFGC catalogue with distances up to 100 h-1 Mpc. We compared the models with multipole velocity field for pure Hubble expansion and dipole, quadrupole and octopole motion with the models with two attractors in the regions indicated by Hoffman et al with the multipole velocity field background. The results do not support the hypothesis, but does not contradict it. In any case, the inclusion of the following multipole is more effective than the addition of two attractors. Estimations of excess mass of attractors vary greatly, even changing their sign depending on the highest multipole used in model.

Dynamical evolution of domain walls in an expanding universe

NASA Technical Reports Server (NTRS)

Press, William H.; Ryden, Barbara S.; Spergel, David N.

1989-01-01

Whenever the potential of a scalar field has two or more separated, degenerate minima, domain walls form as the universe cools. The evolution of the resulting network of domain walls is calculated for the case of two potential minima in two and three dimensions, including wall annihilation, crossing, and reconnection effects. The nature of the evolution is found to be largely independent of the rate at which the universe expands. Wall annihilation and reconnection occur almost as fast as causality allows, so that the horizon volume is 'swept clean' and contains, at any time, only about one, fairly smooth, wall. Quantitative statistics are given. The total area of wall per volume decreases as the first power of time. The relative slowness of the decrease and the smoothness of the wall on the horizon scale make it impossible for walls to both generate large-scale structure and be consistent with quadrupole microwave background anisotropy limits.

Towards AI-powered personalization in MOOC learning

NASA Astrophysics Data System (ADS)

Yu, Han; Miao, Chunyan; Leung, Cyril; White, Timothy John

2017-12-01

Massive Open Online Courses (MOOCs) represent a form of large-scale learning that is changing the landscape of higher education. In this paper, we offer a perspective on how advances in artificial intelligence (AI) may enhance learning and research on MOOCs. We focus on emerging AI techniques including how knowledge representation tools can enable students to adjust the sequence of learning to fit their own needs; how optimization techniques can efficiently match community teaching assistants to MOOC mediation tasks to offer personal attention to learners; and how virtual learning companions with human traits such as curiosity and emotions can enhance learning experience on a large scale. These new capabilities will also bring opportunities for educational researchers to analyse students' learning skills and uncover points along learning paths where students with different backgrounds may require different help. Ethical considerations related to the application of AI in MOOC education research are also discussed.

Ubiquitous and Continuous Propagating Disturbances in the Solar Corona

NASA Astrophysics Data System (ADS)

Morgan, Huw; Hutton, Joseph

2018-02-01

A new processing method applied to Atmospheric Imaging Assembly/Solar Dynamic Observatory observations reveals continuous propagating faint motions throughout the corona. The amplitudes are small, typically 2% of the background intensity. An hour’s data are processed from four AIA channels for a region near disk center, and the motions are characterized using an optical flow method. The motions trace the underlying large-scale magnetic field. The motion vector field describes large-scale coherent regions that tend to converge at narrow corridors. Large-scale vortices can also be seen. The hotter channels have larger-scale regions of coherent motion compared to the cooler channels, interpreted as the typical length of magnetic loops at different heights. Regions of low mean and high time variance in velocity are where the dominant motion component is along the line of sight as a result of a largely vertical magnetic field. The mean apparent magnitude of the optical velocities are a few tens of km s‑1, with different distributions in different channels. Over time, the velocities vary smoothly between a few km s‑1 to 100 km s‑1 or higher, varying on timescales of minutes. A clear bias of a few km s‑1 toward positive x-velocities is due to solar rotation and may be used as calibration in future work. All regions of the low corona thus experience a continuous stream of propagating disturbances at the limit of both spatial resolution and signal level. The method provides a powerful new diagnostic tool for tracing the magnetic field, and to probe motions at sub-pixel scales, with important implications for models of heating and of the magnetic field.

Theoretical and experimental study of bent fully aperiodic large-pitch fibers for enhancing the high-order modes delocalization

NASA Astrophysics Data System (ADS)

du Jeu, Rémi; Dauliat, Romain; Darwich, Dia; Auguste, Jean-Louis; Benoît, Aurélien; Leconte, Baptiste; Malleville, Marie-Alicia; Jamier, Raphaël.; Schuster, Kay; Roy, Philippe

2018-02-01

The power scaling of fiber lasers and amplifiers has triggered an extensive development of large-mode area fibers among which the most promising are the distributed mode filtering fibers and the large-pitch fibers. These structures enable for an effective higher-order modes delocalization and subsequently a singlemode emission. An interesting alternative consists in using the fully-aperiodic large-pitch fibers, into which the standard air-silica photonic crystal cladding is replaced by an aperiodic pattern made of solid low-index inclusions cladding. However, in such a structure, the core and the background cladding material surrounding it must have rigorously the same refractive index. Current synthesis processes and measurement techniques offer respectively a maximum resolution of 5×10-4 and 1×10-4 while the indexmatching must be as precise as 1×10-5 . Lately a gain material with a refractive index 1.5×10-4 higher than that of the background cladding material was fabricated, thus re-confining the first higher-order modes in the core. A numerical study is carried out on the benefit of bending such fully-aperiodic fiber to counteract this phenomenon. Optimized bending axis and radius have been determined. Experiments are done in a laser cavity operating at 1030 nm using an 88cm-long 51μm core diameter ytterbium-doped fiber. Results demonstrate an improvement of the M2 from 1.7 when the fiber is kept straight to 1.2 when it is bent with a 100 to 60 cm bend radius. These primary results are promising for future power scaling.

Allometric Scaling of the Active Hematopoietic Stem Cell Pool across Mammals

PubMed Central

Dingli, David; Pacheco, Jorge M.

2006-01-01

Background Many biological processes are characterized by allometric relations of the type Y = Y 0 Mb between an observable Y and body mass M, which pervade at multiple levels of organization. In what regards the hematopoietic stem cell pool, there is experimental evidence that the size of the hematopoietic stem cell pool is conserved in mammals. However, demands for blood cell formation vary across mammals and thus the size of the active stem cell compartment could vary across species. Methodology/Principle Findings Here we investigate the allometric scaling of the hematopoietic system in a large group of mammalian species using reticulocyte counts as a marker of the active stem cell pool. Our model predicts that the total number of active stem cells, in an adult mammal, scales with body mass with the exponent ¾. Conclusion/Significance The scaling predicted here provides an intuitive justification of the Hayflick hypothesis and supports the current view of a small active stem cell pool supported by a large, quiescent reserve. The present scaling shows excellent agreement with the available (indirect) data for smaller mammals. The small size of the active stem cell pool enhances the role of stochastic effects in the overall dynamics of the hematopoietic system. PMID:17183646

Ground Level Ozone Regional Background Characteristics In North-west Pacific Rim

NASA Astrophysics Data System (ADS)

Chiang, C.; Fan, J.; Chang, J. S.

2007-12-01

Understanding the ground level ozone regional background characteristics is essential in understanding the contribution of long-range transport of pollutants from Asia Mainland to air quality in downwind areas. In order to understand this characteristic in north-west Pacific Rim, we conducted a coupled study using ozone observation from regional background stations and 3-D regional-scale chemical transport model simulations. We used O3, CO, wind speed and wind direction data from two regional background stations and ¡§other stations¡¨ over a ten year period and organized several numerical experiments to simulate one spring month in 2003 to obtain a deeper understanding. The so called ¡§other stations¡¨ had actually been named as background stations under various governmental auspices. But we found them to be often under strong influence of local pollution sources with strong diurnal or slightly longer time variations. We found that the Yonagunijima station (24.74 N, 123.02 E) and Heng-Chuen station (21.96 N,120.78 E), about a distance of 400 km apart, have almost the same ozone time series pattern. For these two stations in 2003, correlation coefficients (R2) for annual observed ozone concentration is about 0.64, in the springtime it is about 0.7, and in a one-month period at simulation days it is about 0.76. These two stations have very little small scale variations in all the variables studied. All variations are associated with large scale circulation changes. This is especially so at Yonagunijima station. Using a 3-D regional-scale chemical transport model for East Asia region including contribution from Asia continental outflow and neighboring island pollution areas we found that the Yonagunijima and HengChuen station are indeed free of pollutants from all neighboring areas keeping in mind that pollutants from Taiwan area is never far away. Ozone concentrations in these two stations are dominated by synoptic scale weather patterns, with diffused pollutant contribution from distant sources. When the weather system brings in air mass from the low latitude of western Pacific Ocean, ozone concentrations are about 10-20 ppb. When the China high pressure system moves eastward and with the accompanying Asian continental outflow plume, ozone concentrations are about 65-80 ppb.

Image Discrimination Models Predict Object Detection in Natural Backgrounds

NASA Technical Reports Server (NTRS)

Ahumada, Albert J., Jr.; Rohaly, A. M.; Watson, Andrew B.; Null, Cynthia H. (Technical Monitor)

1994-01-01

Object detection involves looking for one of a large set of object sub-images in a large set of background images. Image discrimination models only predict the probability that an observer will detect a difference between two images. In a recent study based on only six different images, we found that discrimination models can predict the relative detectability of objects in those images, suggesting that these simpler models may be useful in some object detection applications. Here we replicate this result using a new, larger set of images. Fifteen images of a vehicle in an other-wise natural setting were altered to remove the vehicle and mixed with the original image in a proportion chosen to make the target neither perfectly recognizable nor unrecognizable. The target was also rotated about a vertical axis through its center and mixed with the background. Sixteen observers rated these 30 target images and the 15 background-only images for the presence of a vehicle. The likelihoods of the observer responses were computed from a Thurstone scaling model with the assumption that the detectabilities are proportional to the predictions of an image discrimination model. Three image discrimination models were used: a cortex transform model, a single channel model with a contrast sensitivity function filter, and the Root-Mean-Square (RMS) difference of the digital target and background-only images. As in the previous study, the cortex transform model performed best; the RMS difference predictor was second best; and last, but still a reasonable predictor, was the single channel model. Image discrimination models can predict the relative detectabilities of objects in natural backgrounds.

Probing secret interactions of eV-scale sterile neutrinos with the diffuse supernova neutrino background

NASA Astrophysics Data System (ADS)

Jeong, Yu Seon; Palomares-Ruiz, Sergio; Hall Reno, Mary; Sarcevic, Ina

2018-06-01

Sterile neutrinos with mass in the eV-scale and large mixings of order θ0simeq 0.1 could explain some anomalies found in short-baseline neutrino oscillation data. Here, we revisit a neutrino portal scenario in which eV-scale sterile neutrinos have self-interactions via a new gauge vector boson phi. Their production in the early Universe via mixing with active neutrinos can be suppressed by the induced effective potential in the sterile sector. We study how different cosmological observations can constrain this model, in terms of the mass of the new gauge boson, Mphi, and its coupling to sterile neutrinos, gs. Then, we explore how to probe part of the allowed parameter space of this particular model with future observations of the diffuse supernova neutrino background by the Hyper-Kamiokande and DUNE detectors. For Mphi ~ 5‑10 keV and gs ~ 10‑4‑10‑2, as allowed by cosmological constraints, we find that interactions of diffuse supernova neutrinos with relic sterile neutrinos on their way to the Earth would result in significant dips in the neutrino spectrum which would produce unique features in the event spectra observed in these detectors.

Adaptive Identification and Characterization of Polar Ionization Patches

NASA Technical Reports Server (NTRS)

Coley, W. R.; Heelis, R. A.

1995-01-01

Dynamics Explorer 2 (DE 2) spacecraft data are used to detect and characterize polar cap 'ionization patches' loosely defined as large-scale (greater than 100 km) regions where the F region plasma density is significantly enhanced (approx greater than 100%) above the background level. These patches are generally believed to develop in or equatorward of the dayside cusp region and then drift in an antisunward direction over the polar cap. We have developed a flexible algorithm for the identification and characterization of these structures, as a function of scale-size and density enhancement, using data from the retarding potential analyzer, the ion drift meter, and the langmuir probe on board the DE 2 satellite. This algorithm was used to study the structure and evolution of ionization patches as they cross the polar cap. The results indicate that in the altitude region from 240 to 950 km ion density enhancements greater than a factor of 3 above the background level are relatively rare. Further, the ionization patches show a preferred horizontal scale size of 300-400 km. There exists a clear seasonal and universal time dependence to the occurrence frequency of patches with a northern hemisphere maximum centered on the winter solstice and the 1200-2000 UT interval.

The cosmic web and microwave background fossilize the first turbulent combustion

NASA Astrophysics Data System (ADS)

Gibson, Carl H.

2015-09-01

The weblike structure of the cosmic microwave background CMB temperature fluctuations are interpreted as fossils of the first turbulent combustion that drives the big bang1,2,3. Modern turbulence theory3 requires that inertial vortex forces cause turbulence to always cascade from small scales to large, contrary to the standard turbulence model where the cascade is reversed. Assuming that the universe begins at Planck length 10-35 m and temperature 1032 K, the mechanism of the big bang is a powerful turbulent combustion instability, where turbulence forms at the Kolmogorov scale and mass-energy is extracted by < -10113 Pa negative stresses from big bang turbulence working against gravity. Prograde accretion of a Planck antiparticle on a spinning particle-antiparticle pair releases 42% of a particle rest mass from the Kerr metric, producing a spinning gas of turbulent Planck particles that cascades to larger scales at smaller temperatures (10-27 m, 1027 K) retaining the Planck density 1097 kg m-3, where quarks form and gluon viscosity fossilizes the turbulence. Viscous stress powers inflation to ~ 10 m and ~ 10100 kg. The CMB shows signatures of both plasma and big bang turbulence. Direct numerical simulations support the new turbulence theory6.

Can standard cosmological models explain the observed Abell cluster bulk flow?

NASA Technical Reports Server (NTRS)

Strauss, Michael A.; Cen, Renyue; Ostriker, Jeremiah P.; Laure, Tod R.; Postman, Marc

1995-01-01

Lauer and Postman (LP) observed that all Abell clusters with redshifts less than 15,000 km/s appear to be participating in a bulk flow of 689 km/s with respect to the cosmic microwave background. We find this result difficult to reconcile with all popular models for large-scale structure formation that assume Gaussian initial conditions. This conclusion is based on Monte Carlo realizations of the LP data, drawn from large particle-mesh N-body simulations for six different models of the initial power spectrum (standard, tilted, and Omega(sub 0) = 0.3 cold dark matter, and two variants of the primordial baryon isocurvature model). We have taken special care to treat properly the longest-wavelength components of the power spectra. The simulations are sampled, 'observed,' and analyzed as identically as possible to the LP cluster sample. Large-scale bulk flows as measured from clusters in the simulations are in excellent agreement with those measured from the grid: the clusters do not exhibit any strong velocity bias on large scales. Bulk flows with amplitude as large as that reported by LP are not uncommon in the Monte Carlo data stes; the distribution of measured bulk flows before error bias subtraction is rougly Maxwellian, with a peak around 400 km/s. However the chi squared of the observed bulk flow, taking into account the anisotropy of the error ellipsoid, is much more difficult to match in the simulations. The models examined are ruled out at confidence levels between 94% and 98%.

Disappearance of Anisotropic Intermittency in Large-amplitude MHD Turbulence and Its Comparison with Small-amplitude MHD Turbulence

NASA Astrophysics Data System (ADS)

Yang, Liping; Zhang, Lei; He, Jiansen; Tu, Chuanyi; Li, Shengtai; Wang, Xin; Wang, Linghua

2018-03-01

Multi-order structure functions in the solar wind are reported to display a monofractal scaling when sampled parallel to the local magnetic field and a multifractal scaling when measured perpendicularly. Whether and to what extent will the scaling anisotropy be weakened by the enhancement of turbulence amplitude relative to the background magnetic strength? In this study, based on two runs of the magnetohydrodynamic (MHD) turbulence simulation with different relative levels of turbulence amplitude, we investigate and compare the scaling of multi-order magnetic structure functions and magnetic probability distribution functions (PDFs) as well as their dependence on the direction of the local field. The numerical results show that for the case of large-amplitude MHD turbulence, the multi-order structure functions display a multifractal scaling at all angles to the local magnetic field, with PDFs deviating significantly from the Gaussian distribution and a flatness larger than 3 at all angles. In contrast, for the case of small-amplitude MHD turbulence, the multi-order structure functions and PDFs have different features in the quasi-parallel and quasi-perpendicular directions: a monofractal scaling and Gaussian-like distribution in the former, and a conversion of a monofractal scaling and Gaussian-like distribution into a multifractal scaling and non-Gaussian tail distribution in the latter. These results hint that when intermittencies are abundant and intense, the multifractal scaling in the structure functions can appear even if it is in the quasi-parallel direction; otherwise, the monofractal scaling in the structure functions remains even if it is in the quasi-perpendicular direction.

Using Accelerometers to Measure Physical Activity in Large-Scale Epidemiologic Studies: Issues and Challenges

PubMed Central

Lee, I-Min; Shiroma, Eric J

2013-01-01

Background Current guidelines for aerobic activity require that adults carry out ≥150 minutes/week of moderate-intensity physical activity, with a large body of epidemiologic evidence showing this level of activity to decrease the incidence of many chronic diseases. Less is known about whether light-intensity activities also have such benefits, and whether sedentary behavior is an independent predictor of increased risks of these chronic diseases, as imprecise assessments of these behaviours and cross-sectional study designs have limited knowledge to date. Methods Recent technological advances in assessment methods have made the use of movement sensors, such as the accelerometer, feasible for use in longitudinal, large-scale epidemiologic studies. Several such studies are collecting sensor-assessed, objective measures of physical activity with the aim of relating these to the development of clinical endpoints. This is a relatively new area of research; thus, in this paper, we use the Women’s Health Study (WHS) as a case study to illustrate challenges related to data collection, data processing, and analyses of the vast amount of data collected. Results The WHS plans to collect 7 days of accelerometer-assessed physical activity and sedentary behavior in ~18,000 women aged ≥62 years. Several logistical challenges exist in collecting data; nonetheless as of 31 August 2013, 11,590 women have already provided some data. Additionally, the WHS experience on data reduction and data analyses can help inform other similar large-scale epidemiologic studies. Conclusions Important data on the health effects of light-intensity activity and sedentary behaviour will emerge from large-scale epidemiologic studies collecting objective assessments of these behaviours. PMID:24297837

The formation of galaxies

NASA Technical Reports Server (NTRS)

Efstathiou, G.; Silk, J.

1983-01-01

Current models of galaxy formation are examined in a review of recent observational and theoretical studies. Observational data on elliptical galaxies, disk galaxies, luminosity functions, clustering, and angular fluctuations in the cosmic microwave background are summarized. Theoretical aspects discussed include the origin and early evolution of small fluctuations, matter and radiation fluctuations, the formation of large-scale structure, dissipationless galaxy formation, galaxy mergers, dissipational galaxy formation, and the implications of particle physics (GUTs, massive neutrinos, and gravitinos) for cosmology.

Cosmology: A research briefing

NASA Technical Reports Server (NTRS)

1995-01-01

As part of its effort to update topics dealt with in the 1986 decadal physics survey, the Board on Physics and Astronomy of the National Research Council (NRC) formed a Panel on Cosmology. The Panel produced this report, intended to be accessible to science policymakers and nonscientists. The chapters include an overview ('What Is Cosmology?'), a discussion of cosmic microwave background radiation, the large-scale structure of the universe, the distant universe, and physics of the early universe.

Ellipsoidal universe can solve the cosmic microwave background quadrupole problem.

PubMed

Campanelli, L; Cea, P; Tedesco, L

2006-09-29

The recent 3 yr Wilkinson Microwave Anisotropy Probe data have confirmed the anomaly concerning the low quadrupole amplitude compared to the best-fit Lambda-cold dark matter prediction. We show that by allowing the large-scale spatial geometry of our universe to be plane symmetric with eccentricity at decoupling or order 10(-2), the quadrupole amplitude can be drastically reduced without affecting higher multipoles of the angular power spectrum of the temperature anisotropy.

Background | Office of Cancer Clinical Proteomics Research

Cancer.gov

The term "proteomics" refers to a large-scale comprehensive study of a specific proteome resulting from its genome, including abundances of proteins, their variations and modifications, and interacting partners and networks in order to understand cellular processes involved.  Similarly, “Cancer proteomics” refers to comprehensive analyses of proteins and their derivatives translated from a specific cancer genome using a human biospecimen or a preclinical model (e.g., cultured cell or animal model).

The cascade from local to global dust storms on Mars: Temporal and spatial thresholds on thermal and dynamical feedback

NASA Astrophysics Data System (ADS)

Toigo, Anthony D.; Richardson, Mark I.; Wang, Huiqun; Guzewich, Scott D.; Newman, Claire E.

2018-03-01

We use the MarsWRF general circulation model to examine the temporal and spatial response of the atmosphere to idealized local and regional dust storm radiative heating. The ability of storms to modify the atmosphere away from the location of dust heating is a likely prerequisite for dynamical feedbacks that aid the growth of storms beyond the local scale, while the ability of storms to modify the atmosphere after the cessation of dust radiative heating is potentially important in preconditioning the atmosphere prior to large scale storms. Experiments were conducted over a range of static, prescribed storm sizes, durations, optical depth strengths, locations, and vertical extents of dust heating. Our results show that for typical sizes (order 105 km2) and durations (1-10 sols) of local dust storms, modification of the atmosphere is less than the typical variability of the unperturbed (storm-free) state. Even if imposed on regional storm length scales (order 106 km2), a 1-sol duration storm similarly does not significantly modify the background atmosphere. Only when imposed for 10 sols does a regional dust storm create a significant impact on the background atmosphere, allowing for the possibility of self-induced dynamical storm growth. These results suggest a prototype for how the subjective observational categorization of storms may be related to objective dynamical growth feedbacks that only become available to storms after they achieve a threshold size and duration, or if they grow into an atmosphere preconditioned by a prior large and sustained storm.

Electron Currents and Heating in the Ion Diffusion Region of Asymmetric Reconnection

NASA Technical Reports Server (NTRS)

Graham, D. B.; Khotyaintsev, Yu. V.; Norgren, C.; Vaivads, A.; Andre, M.; Lindqvist, P. A.; Marklund, G. T.; Ergun, R. E.; Paterson, W. R.; Gershman, D. J.;

a Coarse-To Model for Airplane Detection from Large Remote Sensing Images Using Saliency Modle and Deep Learning

NASA Astrophysics Data System (ADS)

Song, Z. N.; Sui, H. G.

2018-04-01

High resolution remote sensing images are bearing the important strategic information, especially finding some time-sensitive-targets quickly, like airplanes, ships, and cars. Most of time the problem firstly we face is how to rapidly judge whether a particular target is included in a large random remote sensing image, instead of detecting them on a given image. The problem of time-sensitive-targets target finding in a huge image is a great challenge: 1) Complex background leads to high loss and false alarms in tiny object detection in a large-scale images. 2) Unlike traditional image retrieval, what we need to do is not just compare the similarity of image blocks, but quickly find specific targets in a huge image. In this paper, taking the target of airplane as an example, presents an effective method for searching aircraft targets in large scale optical remote sensing images. Firstly, we used an improved visual attention model utilizes salience detection and line segment detector to quickly locate suspected regions in a large and complicated remote sensing image. Then for each region, without region proposal method, a single neural network predicts bounding boxes and class probabilities directly from full images in one evaluation is adopted to search small airplane objects. Unlike sliding window and region proposal-based techniques, we can do entire image (region) during training and test time so it implicitly encodes contextual information about classes as well as their appearance. Experimental results show the proposed method is quickly identify airplanes in large-scale images.

Large-scale structure in mimetic Horndeski gravity

NASA Astrophysics Data System (ADS)

Arroja, Frederico; Okumura, Teppei; Bartolo, Nicola; Karmakar, Purnendu; Matarrese, Sabino

2018-05-01

In this paper, we propose to use the mimetic Horndeski model as a model for the dark universe. Both cold dark matter (CDM) and dark energy (DE) phenomena are described by a single component, the mimetic field. In linear theory, we show that this component effectively behaves like a perfect fluid with zero sound speed and clusters on all scales. For the simpler mimetic cubic Horndeski model, if the background expansion history is chosen to be identical to a perfect fluid DE (PFDE) then the mimetic model predicts the same power spectrum of the Newtonian potential as the PFDE model with zero sound speed. In particular, if the background is chosen to be the same as that of LCDM, then also in this case the power spectrum of the Newtonian potential in the mimetic model becomes indistinguishable from the power spectrum in LCDM on linear scales. A different conclusion may be found in the case of non-adiabatic perturbations. We also discuss the distinguishability, using power spectrum measurements from LCDM N-body simulations as a proxy for future observations, between these mimetic models and other popular models of DE. For instance, we find that if the background has an equation of state equal to ‑0.95 then we will be able to distinguish the mimetic model from the PFDE model with unity sound speed. On the other hand, it will be hard to do this distinction with respect to the LCDM model.

Cosmic Infrared Background Sources Clustered Around Quasars

NASA Astrophysics Data System (ADS)

Hall, Kirsten R.; Zakamska, Nadia; Marriage, Tobias; Crichton, Devin; Gralla, Megan

2017-06-01

Powerful quasars can be seen out to large distances. As they reside in massive dark matter halos, they provide a useful tracer of large scale structure. We stack Herschel-SPIRE images at 250, 350, and 500 microns at the locations of 13,000 quasars in redshift bins spanning 0.5 < z < 3.5. While the detected signal is dominated on instrumental beam scales by the unresolved dust emission of the quasar and its host galaxy, at z 2 the extended emission is clearly spatially resolved on Mpc scales. This emission is due to star-forming galaxies clustered around the dark matter halos hosting quasars. We measure radial surface brightness profiles of the stacked images to compute the angular correlation function of dusty star-forming galaxies correlated with quasars. We generate a halo occupation distribution model in order to determine the masses of the dark matter halos in which dusty star forming galaxies reside. We are probing potential changes in the halo mass most efficient at hosting star forming galaxies, and assessing any evidence that this halo mass evolved with redshift in the context of "cosmic downsizing".

CMB spectral distortion constraints on thermal inflation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cho, Kihyun; Stewart, Ewan D.; Hong, Sungwook E.

2017-08-01

Thermal inflation is a second epoch of exponential expansion at typical energy scales V {sup 1/4} ∼ 10{sup 6} {sup ∼} {sup 8} GeV. If the usual primordial inflation is followed by thermal inflation, the primordial power spectrum is only modestly redshifted on large scales, but strongly suppressed on scales smaller than the horizon size at the beginning of thermal inflation, k > k {sub b} = a {sub b} H {sub b}. We calculate the spectral distortion of the cosmic microwave background generated by the dissipation of acoustic waves in this context. For k {sub b} || 10{sup 3}more » Mpc{sup −1}, thermal inflation results in a large suppression of the μ-distortion amplitude, predicting that it falls well below the standard value of μ ≅ 2× 10{sup −8}. Thus, future spectral distortion experiments, similar to PIXIE, can place new limits on the thermal inflation scenario, constraining k {sub b} ∼> 10{sup 3} Mpc{sup −1} if μ ≅ 2× 10{sup −8} were found.« less

Finding structure in the dark: Coupled dark energy, weak lensing, and the mildly nonlinear regime

NASA Astrophysics Data System (ADS)

Miranda, Vinicius; González, Mariana Carrillo; Krause, Elisabeth; Trodden, Mark

2018-03-01

We reexamine interactions between the dark sectors of cosmology, with a focus on robust constraints that can be obtained using only mildly nonlinear scales. While it is well known that couplings between dark matter and dark energy can be constrained to the percent level when including the full range of scales probed by future optical surveys, calibrating matter power spectrum emulators to all possible choices of potentials and couplings requires many computationally expensive n-body simulations. Here we show that lensing and clustering of galaxies in combination with the cosmic microwave background (CMB) are capable of probing the dark sector coupling to the few percent level for a given class of models, using only linear and quasilinear Fourier modes. These scales can, in principle, be described by semianalytical techniques such as the effective field theory of large-scale structure.

Sterile neutrinos in cosmology

NASA Astrophysics Data System (ADS)

Abazajian, Kevork N.

2017-11-01

Sterile neutrinos are natural extensions to the standard model of particle physics in neutrino mass generation mechanisms. If they are relatively light, less than approximately 10 keV, they can alter cosmology significantly, from the early Universe to the matter and radiation energy density today. Here, we review the cosmological role such light sterile neutrinos can play from the early Universe, including production of keV-scale sterile neutrinos as dark matter candidates, and dynamics of light eV-scale sterile neutrinos during the weakly-coupled active neutrino era. We review proposed signatures of light sterile neutrinos in cosmic microwave background and large scale structure data. We also discuss keV-scale sterile neutrino dark matter decay signatures in X-ray observations, including recent candidate ∼3.5 keV X-ray line detections consistent with the decay of a ∼7 keV sterile neutrino dark matter particle.

Consistency restrictions on maximal electric-field strength in quantum field theory.

PubMed

Gavrilov, S P; Gitman, D M

2008-09-26

Quantum field theory with an external background can be considered as a consistent model only if backreaction is relatively small with respect to the background. To find the corresponding consistency restrictions on an external electric field and its duration in QED and QCD, we analyze the mean-energy density of quantized fields for an arbitrary constant electric field E, acting during a large but finite time T. Using the corresponding asymptotics with respect to the dimensionless parameter eET2, one can see that the leading contributions to the energy are due to the creation of particles by the electric field. Assuming that these contributions are small in comparison with the energy density of the electric background, we establish the above-mentioned restrictions, which determine, in fact, the time scales from above of depletion of an electric field due to the backreaction.

Numerical simulation of large-scale field-aligned current generation from finite-amplitude magnetosonic waves

NASA Technical Reports Server (NTRS)

Yamauchi, M.

1994-01-01

A two-dimensional numerical simulation of finite-amplitude magnetohydrodynamic (MHD) magnetosonic waves is performed under a finite-velocity background convection condition. Isothermal cases are considered for simplicity. External dissipation is introduced by assuming that the field-aligned currents are generated in proportion to the accumulated charges. The simulation results are as follows: Paired field-aligned currents are found from the simulated waves. The flow directions of these field-aligned currents depend on the angle between the background convection and the wave normal, and hence two pairs of field-aligned currents are found from a bowed wave if we look at the overall structure. The majority of these field-aligned currents are closed within each pair rather than between two wings. These features are not observed under slow background convection. The result could be applied to the cusp current system and the substorm current system.

Late time cosmological phase transitions 1: Particle physics models and cosmic evolution

NASA Technical Reports Server (NTRS)

Frieman, Joshua A.; Hill, Christopher T.; Watkins, Richard

1991-01-01

We described a natural particle physics basis for late-time phase transitions in the universe. Such a transition can seed the formation of large-scale structure while leaving a minimal imprint upon the microwave background anisotropy. The key ingredient is an ultra-light pseudo-Nambu-Goldstone boson with an astronomically large (O(kpc-Mpc)) Compton wavelength. We analyze the cosmological signatures of and constraints upon a wide class of scenarios which do not involve domain walls. In addition to seeding structure, coherent ultra-light bosons may also provide unclustered dark matter in a spatially flat universe, omega sub phi approx. = 1.

Current Issues in Cosmology

NASA Astrophysics Data System (ADS)

Pecker, Jean-Claude; Narlikar, Jayant

2011-09-01

Part I. Observational Facts Relating to Discrete Sources: 1. The state of cosmology G. Burbidge; 2. The redshifts of galaxies and QSOs E. M. Burbidge and G. Burbidge; 3. Accretion discs in quasars J. Sulentic; Part II. Observational Facts Relating to Background Radiation: 4. CMB observations and consequences F. Bouchet; 5. Abundances of light nuclei K. Olive; 6. Evidence for an accelerating universe or lack of A. Blanchard; Part III. Standard Cosmology: 7. Cosmology, an overview of the standard model F. Bernardeau; 8. What are the building blocks of our universe? K. C. Wali; Part IV. Large-Scale Structure: 9. Observations of large-scale structure V. de Lapparent; 10. Reconstruction of large-scale peculiar velocity fields R. Mohayaee, B. Tully and U. Frisch; Part V. Alternative Cosmologies: 11. The quasi-steady state cosmology J. V. Narlikar; 12. Evidence for iron whiskers in the universe N. C. Wickramasinghe; 13. Alternatives to dark matter: MOND + Mach D. Roscoe; 14. Anthropic principle in cosmology B. Carter; Part VI. Evidence for Anomalous Redshifts: 15. Anomalous redshifts H. C. Arp; 16. Redshifts of galaxies and QSOs: the problem of redshift periodicities G. Burbidge; 17. Statistics of redshift periodicities W. Napier; 18. Local abnormal redshifts J.-C. Pecker; 19. Gravitational lensing and anomalous redshifts J. Surdej, J.-F. Claeskens and D. Sluse; Panel discussion; General discussion; Concluding remarks.

Split luciferase complementation assay to detect regulated protein-protein interactions in rice protoplasts in a large-scale format

PubMed Central

2014-01-01

Background The rice interactome, in which a network of protein-protein interactions has been elucidated in rice, is a useful resource to identify functional modules of rice signal transduction pathways. Protein-protein interactions occur in cells in two ways, constitutive and regulative. While a yeast-based high-throughput method has been widely used to identify the constitutive interactions, a method to detect the regulated interactions is rarely developed for a large-scale analysis. Results A split luciferase complementation assay was applied to detect the regulated interactions in rice. A transformation method of rice protoplasts in a 96-well plate was first established for a large-scale analysis. In addition, an antibody that specifically recognizes a carboxyl-terminal fragment of Renilla luciferase was newly developed. A pair of antibodies that recognize amino- and carboxyl- terminal fragments of Renilla luciferase, respectively, was then used to monitor quality and quantity of interacting recombinant-proteins accumulated in the cells. For a proof-of-concept, the method was applied to detect the gibberellin-dependent interaction between GIBBERELLIN INSENSITIVE DWARF1 and SLENDER RICE 1. Conclusions A method to detect regulated protein-protein interactions was developed towards establishment of the rice interactome. PMID:24987490

Partially acoustic dark matter, interacting dark radiation, and large scale structure

NASA Astrophysics Data System (ADS)

Chacko, Zackaria; Cui, Yanou; Hong, Sungwoo; Okui, Takemichi; Tsai, Yuhsinz

2016-12-01

The standard paradigm of collisionless cold dark matter is in tension with measurements on large scales. In particular, the best fit values of the Hubble rate H 0 and the matter density perturbation σ 8 inferred from the cosmic microwave background seem inconsistent with the results from direct measurements. We show that both problems can be solved in a framework in which dark matter consists of two distinct components, a dominant component and a subdominant component. The primary component is cold and collisionless. The secondary component is also cold, but interacts strongly with dark radiation, which itself forms a tightly coupled fluid. The growth of density perturbations in the subdominant component is inhibited by dark acoustic oscillations due to its coupling to the dark radiation, solving the σ 8 problem, while the presence of tightly coupled dark radiation ameliorates the H 0 problem. The subdominant component of dark matter and dark radiation continue to remain in thermal equilibrium until late times, inhibiting the formation of a dark disk. We present an example of a simple model that naturally realizes this scenario in which both constituents of dark matter are thermal WIMPs. Our scenario can be tested by future stage-IV experiments designed to probe the CMB and large scale structure.

Large-scale geographical variation in eggshell metal and calcium content in a passerine bird (Ficedula hypoleuca).

PubMed

Ruuskanen, Suvi; Laaksonen, Toni; Morales, Judith; Moreno, Juan; Mateo, Rafael; Belskii, Eugen; Bushuev, Andrey; Järvinen, Antero; Kerimov, Anvar; Krams, Indrikis; Morosinotto, Chiara; Mänd, Raivo; Orell, Markku; Qvarnström, Anna; Slate, Fred; Tilgar, Vallo; Visser, Marcel E; Winkel, Wolfgang; Zang, Herwig; Eeva, Tapio

2014-03-01

Birds have been used as bioindicators of pollution, such as toxic metals. Levels of pollutants in eggs are especially interesting, as developing birds are more sensitive to detrimental effects of pollutants than adults. Only very few studies have monitored intraspecific, large-scale variation in metal pollution across a species' breeding range. We studied large-scale geographic variation in metal levels in the eggs of a small passerine, the pied flycatcher (Ficedula hypoleuca), sampled from 15 populations across Europe. We measured 10 eggshell elements (As, Cd, Cr, Cu, Ni, Pb, Zn, Se, Sr, and Ca) and several shell characteristics (mass, thickness, porosity, and color). We found significant variation among populations in eggshell metal levels for all metals except copper. Eggshell lead, zinc, and chromium levels decreased from central Europe to the north, in line with the gradient in pollution levels over Europe, thus suggesting that eggshell can be used as an indicator of pollution levels. Eggshell lead levels were also correlated with soil lead levels and pH. Most of the metals were not correlated with eggshell characteristics, with the exception of shell mass, or with breeding success, which may suggest that birds can cope well with the current background exposure levels across Europe.

Partially acoustic dark matter, interacting dark radiation, and large scale structure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chacko, Zackaria; Cui, Yanou; Hong, Sungwoo

The standard paradigm of collisionless cold dark matter is in tension with measurements on large scales. In particular, the best fit values of the Hubble rate H 0 and the matter density perturbation σ 8 inferred from the cosmic microwave background seem inconsistent with the results from direct measurements. We show that both problems can be solved in a framework in which dark matter consists of two distinct components, a dominant component and a subdominant component. The primary component is cold and collisionless. The secondary component is also cold, but interacts strongly with dark radiation, which itself forms a tightlymore » coupled fluid. The growth of density perturbations in the subdominant component is inhibited by dark acoustic oscillations due to its coupling to the dark radiation, solving the σ 8 problem, while the presence of tightly coupled dark radiation ameliorates the H 0 problem. The subdominant component of dark matter and dark radiation continue to remain in thermal equilibrium until late times, inhibiting the formation of a dark disk. We present an example of a simple model that naturally realizes this scenario in which both constituents of dark matter are thermal WIMPs. Our scenario can be tested by future stage-IV experiments designed to probe the CMB and large scale structure.« less

Accelerating large-scale protein structure alignments with graphics processing units

PubMed Central

2012-01-01

Background Large-scale protein structure alignment, an indispensable tool to structural bioinformatics, poses a tremendous challenge on computational resources. To ensure structure alignment accuracy and efficiency, efforts have been made to parallelize traditional alignment algorithms in grid environments. However, these solutions are costly and of limited accessibility. Others trade alignment quality for speedup by using high-level characteristics of structure fragments for structure comparisons. Findings We present ppsAlign, a parallel protein structure Alignment framework designed and optimized to exploit the parallelism of Graphics Processing Units (GPUs). As a general-purpose GPU platform, ppsAlign could take many concurrent methods, such as TM-align and Fr-TM-align, into the parallelized algorithm design. We evaluated ppsAlign on an NVIDIA Tesla C2050 GPU card, and compared it with existing software solutions running on an AMD dual-core CPU. We observed a 36-fold speedup over TM-align, a 65-fold speedup over Fr-TM-align, and a 40-fold speedup over MAMMOTH. Conclusions ppsAlign is a high-performance protein structure alignment tool designed to tackle the computational complexity issues from protein structural data. The solution presented in this paper allows large-scale structure comparisons to be performed using massive parallel computing power of GPU. PMID:22357132

The decay of isotropic magnetohydrodynamics turbulence and the effects of cross-helicity

NASA Astrophysics Data System (ADS)

Briard, Antoine; Gomez, Thomas

2018-02-01

Decaying homogeneous and isotropic magnetohydrodynamics (MHD) turbulence is investigated numerically at large Reynolds numbers thanks to the eddy-damped quasi-normal Markovian (EDQNM) approximation. Without any background mean magnetic field, the total energy spectrum scales as -3/2$ in the inertial range as a consequence of the modelling. Moreover, the total energy is shown, both analytically and numerically, to decay at the same rate as kinetic energy in hydrodynamic isotropic turbulence: this differs from a previous prediction, and thus physical arguments are proposed to reconcile both results. Afterwards, the MHD turbulence is made imbalanced by an initial non-zero cross-helicity. A spectral modelling is developed for the velocity-magnetic correlation in a general homogeneous framework, which reveals that cross-helicity can contain subtle anisotropic effects. In the inertial range, as the Reynolds number increases, the slope of the cross-helical spectrum becomes closer to -5/3$ than -2$ . Furthermore, the Elsässer spectra deviate from -3/2$ with cross-helicity at large Reynolds numbers. Regarding the pressure spectrum P$ , its kinetic and magnetic parts are found to scale with -2$ in the inertial range, whereas the part due to cross-helicity rather scales in -7/3$ . Finally, the two rd laws for the total energy and cross-helicity are assessed numerically at large Reynolds numbers.

Partially acoustic dark matter, interacting dark radiation, and large scale structure

DOE PAGES

Chacko, Zackaria; Cui, Yanou; Hong, Sungwoo; ...

2016-12-21

The standard paradigm of collisionless cold dark matter is in tension with measurements on large scales. In particular, the best fit values of the Hubble rate H 0 and the matter density perturbation σ 8 inferred from the cosmic microwave background seem inconsistent with the results from direct measurements. We show that both problems can be solved in a framework in which dark matter consists of two distinct components, a dominant component and a subdominant component. The primary component is cold and collisionless. The secondary component is also cold, but interacts strongly with dark radiation, which itself forms a tightlymore » coupled fluid. The growth of density perturbations in the subdominant component is inhibited by dark acoustic oscillations due to its coupling to the dark radiation, solving the σ 8 problem, while the presence of tightly coupled dark radiation ameliorates the H 0 problem. The subdominant component of dark matter and dark radiation continue to remain in thermal equilibrium until late times, inhibiting the formation of a dark disk. We present an example of a simple model that naturally realizes this scenario in which both constituents of dark matter are thermal WIMPs. Our scenario can be tested by future stage-IV experiments designed to probe the CMB and large scale structure.« less

CROSS-CORRELATION OF NEAR- AND FAR-INFRARED BACKGROUND ANISOTROPIES AS TRACED BY SPITZER AND HERSCHEL

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thacker, Cameron; Gong, Yan; Cooray, Asantha

We present the cross-correlation between the far-infrared (far-IR) background fluctuations as measured with the Herschel Space Observatory at 250, 350, and 500 μm and the near-infrared (near-IR) background fluctuations with the Spitzer Space Telescope at 3.6 and 4.5 μm. The cross-correlation between the FIR and NIR background anisotropies is detected such that the correlation coefficient at a few to 10 arcminute angular scale decreases from 0.3 to 0.1 when the FIR wavelength increases from 250 to 500 μm. We model the cross-correlation using a halo model with three components: (a) FIR bright or dusty star-forming galaxies below the masking depth inmore » Herschel maps, (b) NIR faint galaxies below the masking depth, and (c) intra-halo light (IHL), or diffuse stars in dark matter halos, that is likely dominating the large-scale NIR fluctuations. The model is able to reasonably reproduce the auto-correlations at each of the FIR wavelengths and at 3.6 μm and their corresponding cross-correlations. While the FIR and NIR auto-correlations are dominated by faint, dusty, star-forming galaxies and IHL, respectively, we find that roughly half of the cross-correlation between the NIR and FIR backgrounds is due to the same dusty galaxies that remain unmasked at 3.6 μm. The remaining signal in the cross-correlation is due to IHL present in the same dark matter halos as those hosting the same faint and unmasked galaxies.« less

Ariadne's Thread: A Robust Software Solution Leading to Automated Absolute and Relative Quantification of SRM Data.

PubMed

Nasso, Sara; Goetze, Sandra; Martens, Lennart

2015-09-04

Selected reaction monitoring (SRM) MS is a highly selective and sensitive technique to quantify protein abundances in complex biological samples. To enhance the pace of SRM large studies, a validated, robust method to fully automate absolute quantification and to substitute for interactive evaluation would be valuable. To address this demand, we present Ariadne, a Matlab software. To quantify monitored targets, Ariadne exploits metadata imported from the transition lists, and targets can be filtered according to mProphet output. Signal processing and statistical learning approaches are combined to compute peptide quantifications. To robustly estimate absolute abundances, the external calibration curve method is applied, ensuring linearity over the measured dynamic range. Ariadne was benchmarked against mProphet and Skyline by comparing its quantification performance on three different dilution series, featuring either noisy/smooth traces without background or smooth traces with complex background. Results, evaluated as efficiency, linearity, accuracy, and precision of quantification, showed that Ariadne's performance is independent of data smoothness and complex background presence and that Ariadne outperforms mProphet on the noisier data set and improved 2-fold Skyline's accuracy and precision for the lowest abundant dilution with complex background. Remarkably, Ariadne could statistically distinguish from each other all different abundances, discriminating dilutions as low as 0.1 and 0.2 fmol. These results suggest that Ariadne offers reliable and automated analysis of large-scale SRM differential expression studies.

Correlations Between the Cosmic X-Ray and Microwave Backgrounds: Constraints on a Cosmological Constant

NASA Technical Reports Server (NTRS)

Boughn, S. P.; Crittenden, R. G.; Turok, N. G.

1998-01-01

In universes with significant curvature or cosmological constant, cosmic microwave background (CMB) anisotropies are created very recently via the Rees-Sciama or integrated Sachs-Wolfe effects. This causes the CMB anisotropies to become partially correlated with the local matter density (z less than 4). We examine the prospects of using the hard (2- 10 keV) X-ray background as a probe of the local density and the measured correlation between the HEAO1 A2 X-ray survey and the 4-year COBE-DMR map to obtain a constraint on the cosmological constant. The 95% confidence level upper limit on the cosmological constant is OMega(sub Lambda) less than or equal to 0.5, assuming that the observed fluctuations in the X-ray map result entirely from large scale structure. (This would also imply that the X-rays trace matter with a bias factor of b(sub x) approx. = 5.6 Omega(sub m, sup 0.53)). This bound is weakened considerably if a large portion of the X-ray fluctuations arise from Poisson noise from unresolved sources. For example, if one assumes that the X-ray bias is b(sub x) = 2, then the 95% confidence level upper limit is weaker, Omega(sub Lambda) less than or equal to 0.7. More stringent limits should be attainable with data from the next generation of CMB and X-ray background maps.

Cosmic Microwave Background Mapmaking with a Messenger Field

NASA Astrophysics Data System (ADS)

Huffenberger, Kevin M.; Næss, Sigurd K.

2018-01-01

We apply a messenger field method to solve the linear minimum-variance mapmaking equation in the context of Cosmic Microwave Background (CMB) observations. In simulations, the method produces sky maps that converge significantly faster than those from a conjugate gradient descent algorithm with a diagonal preconditioner, even though the computational cost per iteration is similar. The messenger method recovers large scales in the map better than conjugate gradient descent, and yields a lower overall χ2. In the single, pencil beam approximation, each iteration of the messenger mapmaking procedure produces an unbiased map, and the iterations become more optimal as they proceed. A variant of the method can handle differential data or perform deconvolution mapmaking. The messenger method requires no preconditioner, but a high-quality solution needs a cooling parameter to control the convergence. We study the convergence properties of this new method and discuss how the algorithm is feasible for the large data sets of current and future CMB experiments.

Three-mirror anastigmat for cosmic microwave background observations.

PubMed

Padin, S

2018-03-20

An off-axis three-mirror anastigmat is proposed for future cosmic microwave background observations. The telescope has a 5 m diameter primary, giving 1.5 ' angular resolution at λ=2  mm, which is sufficient for measurements of gravitational lensing and for galaxy cluster surveys. The design includes several key features, not previously combined in a large telescope, that are important for sensitive measurements, especially on large angular scales: (1) high throughput (8° diameter diffraction-limited field of view at λ=1  mm, and 12×8° at λ=3  mm, so a single telescope could support all the detectors for an optimistic, future experiment); (2) low scattering (all the mirrors are small enough to be monolithic, so there are no segment gaps); (3) full boresight rotation, over the full elevation range, for measuring polarization errors; and (4) a comoving shield or baffle around the entire telescope to control pickup.

Particulate matter emissions from biochar-amended soils as a potential tradeoff to the negative emission potential

NASA Astrophysics Data System (ADS)

Ravi, Sujith; Sharratt, Brenton S.; Li, Junran; Olshevski, Stuart; Meng, Zhongju; Zhang, Jianguo

2016-10-01

Novel carbon sequestration strategies such as large-scale land application of biochar may provide sustainable pathways to increase the terrestrial storage of carbon. Biochar has a long residence time in the soil and hence comprehensive studies are urgently needed to quantify the environmental impacts of large-scale biochar application. In particular, black carbon emissions from soils amended with biochar may counteract the negative emission potential due to the impacts on air quality, climate, and biogeochemical cycles. We investigated, using wind tunnel experiments, the particulate matter emission potential of a sand and two agriculturally important soils amended with different concentrations of biochar, in comparison to control soils. Our results indicate that biochar application considerably increases particulate emissions possibly by two mechanisms-the accelerated emission of fine biochar particles and the generation and emission of fine biochar particles resulting from abrasion of large biochar particles by sand grains. Our study highlights the importance of considering the background soil properties (e.g., texture) and geomorphological processes (e.g., aeolian transport) for biochar-based carbon sequestration programs.

Understanding how the shape and spatial distribution of ULVZs provides insight into their cause and to the nature of global-scale mantle convection

NASA Astrophysics Data System (ADS)

McNamara, Allen; Li, Mingming; Garnero, Ed; Marin, Nicole

2017-04-01

Seismic observations of the lower mantle infer multiple scales of compositional heterogeneity. The largest-scale heterogeneity, observed in seismic tomography models, is in the form of large, nearly antipodal regions referred to as the Large Low Shear Velocity Provinces (LLSVPs). In contrast, diffracted wave and core-reflection precursor seismic studies reveal small-scale Ultra Low Velocity Zones (ULVZs) at the base of the mantle that are almost two orders of magnitude smaller than the LLSVPs. We hypothesize that ULVZs provide insight into the nature of LLSVPs, and the LLSVPs, in turn, provide clues to the nature of global-scale mantle convection and compositional state. However, both LLSVPs and ULVZs are observations, and it remains unclear what is causing them. Here, we examine several related questions to aid in understanding their cause and the dynamical processes associated with them. Can we use seismic observations of ULVZ locations to differentiate whether they are caused by compositional heterogeneity or simply partial melting in otherwise normal mantle? Can we use the map-view shape of ULVZs to tell us about lowermost mantle flow directions and the temporal stability of these flow directions? Can the cross-sectional morphology of ULVZs tell us something about the viscosity difference between LLSVPs and background mantle? We performed geodynamical experiments to help answer these questions. We find that ULVZs caused by compositional heterogeneity preferentially form patch-like shapes along the margins of LLSVPs. Rounded patches indicate regions with long-lived stable mantle flow patterns, and linear patches indicate changing mantle flow patterns. Typically, these ULVZ patches have an asymmetrical cross-sectional shape; however, if LLSVPs have a larger grain-size than background mantle, their increased diffusion creep viscosity will act to make them more symmetrical. Alternatively, ULVZs caused simply by partial melting of normal mantle are preferentially located significantly inboard of LLSVP margins and have relatively symmetrical cross-sectional shapes. These results can prompt new seismic studies to better constrain the cause and dynamic significance of multi-scale compositional heterogeneity in the Earth's mantle.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Freese, Katherine; Kinney, William H., E-mail: ktfreese@umich.edu, E-mail: whkinney@buffalo.edu

Natural inflation is a good fit to all cosmic microwave background (CMB) data and may be the correct description of an early inflationary expansion of the Universe. The large angular scale CMB polarization experiment BICEP2 has announced a major discovery, which can be explained as the gravitational wave signature of inflation, at a level that matches predictions by natural inflation models. The natural inflation (NI) potential is theoretically exceptionally well motivated in that it is naturally flat due to shift symmetries, and in the simplest version takes the form V(φ) = Λ{sup 4} [1 ± cos(Nφ/f)]. A tensor-to-scalar ratio r > 0.1 as seen by BICEP2 requiresmore » the height of any inflationary potential to be comparable to the scale of grand unification and the width to be comparable to the Planck scale. The Cosine Natural Inflation model agrees with all cosmic microwave background measurements as long as f ≥ m{sub Pl} (where m{sub Pl} = 1.22 × 10{sup 19} GeV) and Λ ∼ m{sub GUT} ∼ 10{sup 16} GeV. This paper also discusses other variants of the natural inflation scenario: we show that axion monodromy with potential V∝ φ{sup 2/3} is inconsistent with the BICEP2 limits at the 95% confidence level, and low-scale inflation is strongly ruled out. Linear potentials V ∝ φ are inconsistent with the BICEP2 limit at the 95% confidence level, but are marginally consistent with a joint Planck/BICEP2 limit at 95%. We discuss the pseudo-Nambu Goldstone model proposed by Kinney and Mahanthappa as a concrete realization of low-scale inflation. While the low-scale limit of the model is inconsistent with the data, the large-field limit of the model is marginally consistent with BICEP2. All of the models considered predict negligible running of the scalar spectral index, and would be ruled out by a detection of running.« less

High cell density media for Escherichia coli are generally designed for aerobic cultivations – consequences for large-scale bioprocesses and shake flask cultures

PubMed Central

Soini, Jaakko; Ukkonen, Kaisa; Neubauer, Peter

2008-01-01

Background For the cultivation of Escherichia coli in bioreactors trace element solutions are generally designed for optimal growth under aerobic conditions. They do normally not contain selenium and nickel. Molybdenum is only contained in few of them. These elements are part of the formate hydrogen lyase (FHL) complex which is induced under anaerobic conditions. As it is generally known that oxygen limitation appears in shake flask cultures and locally in large-scale bioreactors, function of the FHL complex may influence the process behaviour. Formate has been described to accumulate in large-scale cultures and may have toxic effects on E. coli. Although the anaerobic metabolism of E. coli is well studied, reference data which estimate the impact of the FHL complex on bioprocesses of E. coli with oxygen limitation have so far not been published, but are important for a better process understanding. Results Two sets of fed-batch cultures with conditions triggering oxygen limitation and formate accumulation were performed. Permanent oxygen limitation which is typical for shake flask cultures was caused in a bioreactor by reduction of the agitation rate. Transient oxygen limitation, which has been described to eventually occur in the feed-zone of large-scale bioreactors, was mimicked in a two-compartment scale-down bioreactor consisting of a stirred tank reactor and a plug flow reactor (PFR) with continuous glucose feeding into the PFR. In both models formate accumulated up to about 20 mM in the culture medium without addition of selenium, molybdenum and nickel. By addition of these trace elements the formate accumulation decreased below the level observed in well-mixed laboratory-scale cultures. Interestingly, addition of the extra trace elements caused accumulation of large amounts of lactate and reduced biomass yield in the simulator with permanent oxygen limitation, but not in the scale-down two-compartment bioreactor. Conclusion The accumulation of formate in oxygen limited cultivations of E. coli can be fully prevented by addition of the trace elements selenium, nickel and molybdenum, necessary for the function of FHL complex. For large-scale cultivations, if glucose gradients are likely, the results from the two-compartment scale-down bioreactor indicate that the addition of the extra trace elements is beneficial. No negative effects on the biomass yield or on any other bioprocess parameters could be observed in cultures with the extra trace elements if the cells were repeatedly exposed to transient oxygen limitation. PMID:18687130

Tracing Galactic Outflows to the Source: Spatially Resolved Feedback in M83 with COS

NASA Astrophysics Data System (ADS)

Aloisi, Alessandra

2016-10-01

Star-formation (SF) feedback plays a vital role in shaping galaxy properties, but there are many open questions about how this feedback is created, propagated, and felt by galaxies. SF-driven feedback can be observationally constrained with rest-frame UV absorption-line spectroscopy that accesses a range of powerful gas density and kinematic diagnostics. Studies at both high and low redshift show clear evidence for large-scale outflows in star-forming galaxies that scale with galaxy SF rate. However, by sampling one sightline or the galaxy as a whole, these studies are not tailored to reveal how the large-scale outflows develop from their ultimate sources at the scale of individual SF regions. We propose the first spatially-resolved COS G130M/G160M (1130-1800 A) study of the ISM in the nearby (4.6 Mpc) face-on spiral starburst M83 using individual young star clusters as background sources. This is the first down-the-barrel study where blueshifted absorptions can be identified directly with outflowing gas in a spatially resolved fashion. The kpc-scale flows sampled by the COS pointings will be anchored to the properties of the large-scale (10-100 kpc) flows thanks to the wealth of multi-wavelength observations of M83 from X-ray to radio. A comparison of COS data with mock spectra from constrained simulations of spiral galaxies with FIRE (Feedback In Realistic Environments; a code with unprecedented 1-100 pc spatial resolution and self-consistent treatments of stellar feedback) will provide an important validation of these simulations and will supply the community with a powerful and well-tested tool for galaxy formation predictions applicable to all redshifts.

Adult Chinese as a Second Language Learners' Willingness to Communicate in Chinese: Effects of Cultural, Affective, and Linguistic Variables.

PubMed

Liu, Meihua

2017-06-01

The present research explored the effects of cultural, affective, and linguistic variables on adult Chinese as a second language learners' willingness to communicate in Chinese. One hundred and sixty-two Chinese as a second language learners from a Chinese university answered the Willingness to Communicate in Chinese Scale, the Intercultural Sensitivity Scale, Chinese Speaking Anxiety Scale, Chinese Learning Motivation Scale, Use of Chinese Profile, as well as the Background Questionnaire. The major findings were as follows: (1) the Willingness to Communicate in Chinese Scales were significantly negatively correlated with Chinese Speaking Anxiety Scale but positively correlated with length of stay in China and (2) Chinese Speaking Anxiety Scale was a powerful negative predictor for the overall willingness to communicate in Chinese and the Willingness to Communicate in Chinese Scales, followed by length of stay in China, Chinese Learning Motivation Scale, interaction attentiveness, and Chinese proficiency level. Apparently, students' willingness to communicate in Chinese is largely determined by their Chinese Speaking Anxiety Scale level and length of stay in China, mediated by other variables such as Chinese proficiency level and intercultural communication sensitivity level.

PedsQL™ Multidimensional Fatigue Scale in Sickle Cell Disease: Feasibility, Reliability and Validity

PubMed Central

Panepinto, Julie A.; Torres, Sylvia; Bendo, Cristiane B.; McCavit, Timothy L.; Dinu, Bogdan; Sherman-Bien, Sandra; Bemrich-Stolz, Christy; Varni, James W.

2013-01-01

Background Sickle cell disease (SCD) is an inherited blood disorder characterized by a chronic hemolytic anemia that can contribute to fatigue and global cognitive impairment in patients. The study objective was to report on the feasibility, reliability, and validity of the PedsQL™ Multidimensional Fatigue Scale in SCD for pediatric patient self-report ages 5–18 years and parent proxy-report for ages 2–18 years. Procedure This was a cross-sectional multi-site study whereby 240 pediatric patients with SCD and 303 parents completed the 18-item PedsQL™ Multidimensional Fatigue Scale. Participants also completed the PedsQL™ 4.0 Generic Core Scales. Results The PedsQL™ Multidimensional Fatigue Scale evidenced excellent feasibility, excellent reliability for the Total Scale Scores (patient self-report α = 0.90; parent proxy-report α = 0.95), and acceptable reliability for the three individual scales (patient self-report α = 0.77–0.84; parent proxy-report α = 0.90–0.97). Intercorrelations of the PedsQL™ Multidimensional Fatigue Scale with the PedsQL™ Generic Core Scales were predominantly in the large (≥ 0.50) range, supporting construct validity. PedsQL™ Multidimensional Fatigue Scale Scores were significantly worse with large effects sizes (≥0.80) for patients with SCD than for a comparison sample of healthy children, supporting known-groups discriminant validity. Confirmatory factor analysis demonstrated an acceptable to excellent model fit in SCD. Conclusions The PedsQL™ Multidimensional Fatigue Scale demonstrated acceptable to excellent measurement properties in SCD. The results demonstrate the relative severity of fatigue symptoms in pediatric patients with SCD, indicating the potential clinical utility of multidimensional assessment of fatigue in patients with SCD in clinical research and practice. PMID:24038960

Assessing the harms of cannabis cultivation in Belgium.

PubMed

Paoli, Letizia; Decorte, Tom; Kersten, Loes

2015-03-01

Since the 1990s, a shift from the importation of foreign cannabis to domestic cultivation has taken place in Belgium, as it has in many other countries. This shift has prompted Belgian policy-making bodies to prioritize the repression of cannabis cultivation. Against this background, the article aims to systematically map and assess for the first time ever the harms associated with cannabis cultivation, covering the whole spectrum of growers. This study is based on a web survey primarily targeting small-scale growers (N=1293) and on three interconnected sets of qualitative data on large-scale growers and traffickers (34 closed criminal proceedings, interviews with 32 criminal justice experts, and with 17 large-scale cannabis growers and three traffickers). The study relied on Greenfield and Paoli's (2013) harm assessment framework to identify the harms associated with cannabis cultivation and to assess the incidence, severity and causes of such harms. Cannabis cultivation has become endemic in Belgium. Despite that, it generates, for Belgium, limited harms of medium-low or medium priority. Large-scale growers tend to produce more harms than the small-scale ones. Virtually all the harms associated with cannabis cultivation are the result of the current criminalizing policies. Given the spread of cannabis cultivation and Belgium's position in Europe, reducing the supply of cannabis does not appear to be a realistic policy objective. Given the limited harms generated, there is scarce scientific justification to prioritize cannabis cultivation in Belgian law enforcement strategies. As most harms are generated by large-scale growers, it is this category of cultivator, if any, which should be the focus of law enforcement repression. Given the policy origin of most harms, policy-makers should seek to develop policies likely to reduce such harms. At the same time, further research is needed to comparatively assess the harms associated with cannabis cultivation (and trafficking) with those arising from use. Copyright © 2014 Elsevier B.V. All rights reserved.

Regional Air Pollutions in Three Different Regions of Asia From a Transcontinental Transport Perspective

NASA Astrophysics Data System (ADS)

Pochanart, P.; Kanaya, Y.; Komazaki, Y.; Liu, Y.; Akimoto, H.

2007-12-01

Asia is known as one of the regions with the fastest rate of growing in industrialization and urbanization. As a result, the rapid increases of large-scale air pollution in Asia emerge as a serious concern at both domestic and international levels. Apart from the problems of air quality degradation, emission control, environmental risk, and health effect in a domestic level, evidences from scientific studies indicate that by the long-range transport, Asian air pollution is becoming a global problem. Observations and model studies confirm that air pollution from Asia could be transported to North America or farther. In this work, we investigate the Asian air pollutions, in particular ozone and some other atmospheric components such as carbon monoxide and black carbon, from the ground- based observations in the three different regions, namely 1) background region of Siberia and central Asia, 2) highly anthropogenic region in eastern China, and 3) the rim region of the Asia-Pacific. In a transcontinental transport perspective, these regions are regarded as the inflow region, source region, and outflow region of Asia, respectively. From the results, it is found that the influences from large-scale emission in East Asia are observed clearly in the source region, and to the significant extent in the outflow region. For the inflow region of Asia, our data in Siberia and Kyrgyzstan indicate that air masses in this region are mostly intact from large-scale anthropogenic emission, and remain much of the global background atmospheric pollution characteristic. When the air masses are transported to source region, the air pollutants level increased sharply and frequent episodes of extremely high pollutions have been observed. Our results show good correlation between the residence time of air masses over the source region in eastern China and the observed levels of air pollutants verifying the strong enhancements by anthropogenic emissions from industrialization and urbanization. In the outflow region, air pollutants characteristics depend largely on the air mass climatology. In most cases, increases of air pollutants level are observed with the transport events directly from the source region.

From symptoms to social functioning: differential effects of antidepressant therapy.

PubMed

Kasper, S

1999-05-01

Significant impairments in social functioning frequently occur simultaneously with depressive symptoms. The implications of such impairments extend beyond the depressed individual to their family, friends and society at large. Classical rating scales such as the Hamilton rating scale for depression primarily assess the core symptoms of depression. A range of rating scales are available, both self-reporting and administered by clinician; however, many have been criticised for their unspecified conceptual background and for being complex and time-consuming. While antidepressants in general appear to improve social functioning, no clear advantage for any single class of agent has been reported. Recently, a new self-report rating scale, the Social Adaptation Self-evaluation Scale, has been developed and used to compare the novel selective noradrenaline reuptake inhibitor, reboxetine, with the selective serotonin re-uptake inhibitor, fluoxetine. The noradrenergic agent, reboxetine, was shown to be significantly more effective in improving social functioning than the serotonergic agent, fluoxetine. These findings are consistent with previous observations that noradrenaline may preferentially improve vigilance, motivation and self-perception.

Yemen: Background and U.S. Relations

DTIC Science & Technology

2010-07-28

Respondents should be aware that notwithstanding any other provision of law , no person shall be subject to a penalty for failing to comply with a...large-scale U.S. support. Over the past several fiscal years, Yemen has received on average between $20 and $25 million annually in total U.S. foreign...against a republican movement backed by Egypt ultimately led to the dissolution of the Yemeni Imamate and the creation of the Yemen Arab Republic ( YAR ). In

Ways to improve your correlation functions

NASA Technical Reports Server (NTRS)

Hamilton, A. J. S.

1993-01-01

This paper describes a number of ways to improve on the standard method for measuring the two-point correlation function of large scale structure in the Universe. Issues addressed are: (1) the problem of the mean density, and how to solve it; (2) how to estimate the uncertainty in a measured correlation function; (3) minimum variance pair weighting; (4) unbiased estimation of the selection function when magnitudes are discrete; and (5) analytic computation of angular integrals in background pair counts.

The workshop. [use and application of remotely sensed data

NASA Technical Reports Server (NTRS)

Wake, W. H.

1981-01-01

The plan is presented for a two day workshop held to provide educational and training experience in the reading, interpretation, and application of LANDSAT and correlated larger scale imagery, digital printout maps, and other collateral material for a large number of participants with widely diverse levels of expertise, backgrounds, and occupations in government, industry, and education. The need for using surface truth field studies with correlated aerial imagery in solving real world problems was demonstrated.

Fiber Optic Rosette Strain Gauge Development and Application on a Large-Scale Composite Structure

NASA Technical Reports Server (NTRS)

Moore, Jason P.; Przekop, Adam; Juarez, Peter D.; Roth, Mark C.

2015-01-01

A detailed description of the construction, application, and measurement of 196 FO rosette strain gauges that measured multi-axis strain across the outside upper surface of the forward bulkhead component of a multibay composite fuselage test article is presented. A background of the FO strain gauge and the FO measurement system as utilized in this application is given and results for the higher load cases of the testing sequence are shown.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hausegger, Sebastian von; Liu, Hao; Sarkar, Subir

Cosmology has made enormous progress through studies of the cosmic microwave background, however the subtle signals being now sought such as B-mode polarisation due to primordial gravitational waves are increasingly hard to disentangle from residual Galactic foregrounds in the derived CMB maps. We revisit our finding that on large angular scales there are traces of the nearby old supernova remnant Loop I in the WMAP 9-year map of the CMB and confirm this with the new SMICA map from the Planck satellite.

AzTEC Millimetre Survey of the COSMOS field - II. Source count overdensity and correlations with large-scale structure

NASA Astrophysics Data System (ADS)

Austermann, J. E.; Aretxaga, I.; Hughes, D. H.; Kang, Y.; Kim, S.; Lowenthal, J. D.; Perera, T. A.; Sanders, D. B.; Scott, K. S.; Scoville, N.; Wilson, G. W.; Yun, M. S.

2009-03-01

We report an overdensity of bright submillimetre galaxies (SMGs) in the 0.15 deg2 AzTEC/COSMOS survey and a spatial correlation between the SMGs and the optical-IR galaxy density at z <~ 1.1. This portion of the COSMOS field shows a ~3σ overdensity of robust SMG detections when compared to a background, or `blank-field', population model that is consistent with SMG surveys of fields with no extragalactic bias. The SMG overdensity is most significant in the number of very bright detections (14 sources with measured fluxes S1.1mm > 6 mJy), which is entirely incompatible with sample variance within our adopted blank-field number densities and infers an overdensity significance of >> 4σ. We find that the overdensity and spatial correlation to optical-IR galaxy density are most consistent with lensing of a background SMG population by foreground mass structures along the line of sight, rather than physical association of the SMGs with the z <~ 1.1 galaxies/clusters. The SMG positions are only weakly correlated with weak-lensing maps, suggesting that the dominant sources of correlation are individual galaxies and the more tenuous structures in the survey region, and not the massive and compact clusters. These results highlight the important roles cosmic variance and large-scale structure can play in the study of SMGs.

Efficient Plasma Production in Low Background Neutral Pressures with the M2P2 Prototype

NASA Technical Reports Server (NTRS)

Ziemba, T.; Euripides, P.; Winglee, R.; Slough, J.; Giersch, L.

2003-01-01

Mini-Magnetospheric Plasma Propulsion (M2P2) seeks the creation of a large-scale (10 km radius) magnetic wall or bubble (i.e. a magnetosphere) by the electromagnetic inflation of a small-scale (20 cm radius) dipole magnet. The inflated magnetosphere will intercept the solar wind and thereby provide high-speed propulsion with modest power and fuel requirements due to the gain provided by the ambient medium. Magnetic field inflation is produced by the injection of plasma onto the dipole magnetic field eliminating the need for large mechanical structures and added material weight at launch. For successful inflation of the magnetic bubble a beta near unity must be achieved along the imposed dipole field. This is dependent on the plasma parameters that can be achieved with a plasma source that provide continuous operation at the desired power levels of 1 to 2 kilowatts. Over the last two years we have been developing a laboratory prototype to demonstrate the inflation of the magnetic field under space-like conditions. In this paper we will present some of the latest results from the prototype development at the University of Washington and show that the prototype can produce high ionization efficiencies while operating in near space like neutral background pressures producing electron temperatures of a few tens of electron volts. This allows for operation with propellant expenditures lower than originally estimated.

MassiveNuS: cosmological massive neutrino simulations

NASA Astrophysics Data System (ADS)

Liu, Jia; Bird, Simeon; Zorrilla Matilla, José Manuel; Hill, J. Colin; Haiman, Zoltán; Madhavacheril, Mathew S.; Petri, Andrea; Spergel, David N.

2018-03-01

The non-zero mass of neutrinos suppresses the growth of cosmic structure on small scales. Since the level of suppression depends on the sum of the masses of the three active neutrino species, the evolution of large-scale structure is a promising tool to constrain the total mass of neutrinos and possibly shed light on the mass hierarchy. In this work, we investigate these effects via a large suite of N-body simulations that include massive neutrinos using an analytic linear-response approximation: the Cosmological Massive Neutrino Simulations (MassiveNuS). The simulations include the effects of radiation on the background expansion, as well as the clustering of neutrinos in response to the nonlinear dark matter evolution. We allow three cosmological parameters to vary: the neutrino mass sum Mν in the range of 0–0.6 eV, the total matter density Ωm, and the primordial power spectrum amplitude As. The rms density fluctuation in spheres of 8 comoving Mpc/h (σ8) is a derived parameter as a result. Our data products include N-body snapshots, halo catalogues, merger trees, ray-traced galaxy lensing convergence maps for four source redshift planes between zs=1–2.5, and ray-traced cosmic microwave background lensing convergence maps. We describe the simulation procedures and code validation in this paper. The data are publicly available at http://columbialensing.org.

Understanding the large-scale structure from the cosmic microwave background: shear calibration with CMB lensing; gas physics from the kinematic Sunyaev-Zel'dovich effect

NASA Astrophysics Data System (ADS)

Schaan, Emmanuel

2017-01-01

I will present two promising ways in which the cosmic microwave background (CMB) sheds light on critical uncertain physics and systematics of the large-scale structure. Shear calibration with CMB lensing: Realizing the full potential of upcoming weak lensing surveys requires an exquisite understanding of the errors in galaxy shape estimation. In particular, such errors lead to a multiplicative bias in the shear, degenerate with the matter density parameter and the amplitude of fluctuations. Its redshift-evolution can hide the true evolution of the growth of structure, which probes dark energy and possible modifications to general relativity. I will show that CMB lensing from a stage 4 experiment (CMB S4) can self-calibrate the shear for an LSST-like optical lensing survey. This holds in the presence of photo-z errors and intrinsic alignment. Evidence for the kinematic Sunyaev-Zel'dovich (kSZ) effect; cluster energetics: Through the kSZ effect, the baryon momentum field is imprinted on the CMB. I will report significant evidence for the kSZ effect from ACTPol and peculiar velocities reconstructed from BOSS. I will present the prospects for constraining cluster gas profiles and energetics from the kSZ effect with SPT-3G, AdvACT and CMB S4. This will provide constraints on galaxy formation and feedback models.

Short time-scale optical pulsations in the night sky background

NASA Technical Reports Server (NTRS)

Bertsch, D. L.; Fisher, A.; Ogelman, H.

1971-01-01

A network of monitoring stations designed to detect large scale fluorescence emission in the atmosphere has been in operation for over two years. The motivation for the search arises from the prediction that an energetic photon burst would be produced in a supernova and this burst, when absorbed in the atmosphere, would produce fluorescence. This paper reports on observations up to February 1971. No supernova-like events have been found, although 4.4 were expected. One class of non-fluorescence events is described that evidence suggests is related to electrical discharge in the atmosphere. Another type of non-fluorescence pulse appears to be related to particle precipitation in the atmosphere.

The cosmic web and microwave background fossilize the first turbulent combustion

NASA Astrophysics Data System (ADS)

Gibson, Carl H.; Keeler, R. Norris

2016-10-01

Collisional fluid mechanics theory predicts a turbulent hot big bang at Planck conditions from large, negative, turbulence stresses below the Fortov-Kerr limit (< -10113 Pa). Big bang turbulence fossilized when quarks formed, extracting the mass energy of the universe by extreme negative viscous stresses of inflation, expanding to length scales larger than the horizon scale ct. Viscous-gravitational structure formation by fragmentation was triggered at big bang fossil vorticity turbulence vortex lines during the plasma epoch, as observed by the Planck space telescope. A cosmic web of protogalaxies, protogalaxyclusters, and protogalaxysuperclusters that formed in turbulent boundary layers of the spinning voids are hereby identified as expanding turbulence fossils that falsify CDMHC cosmology.

Study of muon-induced neutron production using accelerator muon beam at CERN

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nakajima, Y.; Lin, C. J.; Ochoa-Ricoux, J. P.

2015-08-17

Cosmogenic muon-induced neutrons are one of the most problematic backgrounds for various underground experiments for rare event searches. In order to accurately understand such backgrounds, experimental data with high-statistics and well-controlled systematics is essential. We performed a test experiment to measure muon-induced neutron production yield and energy spectrum using a high-energy accelerator muon beam at CERN. We successfully observed neutrons from 160 GeV/c muon interaction on lead, and measured kinetic energy distributions for various production angles. Works towards evaluation of absolute neutron production yield is underway. This work also demonstrates that the setup is feasible for a future large-scale experimentmore » for more comprehensive study of muon-induced neutron production.« less

Polarization of Cosmic Microwave Background

NASA Astrophysics Data System (ADS)

Buzzelli, A.; Cabella, P.; de Gasperis, G.; Vittorio, N.

2016-02-01

In this work we present an extension of the ROMA map-making code for data analysis of Cosmic Microwave Background polarization, with particular attention given to the inflationary polarization B-modes. The new algorithm takes into account a possible cross- correlated noise component among the different detectors of a CMB experiment. We tested the code on the observational data of the BOOMERanG (2003) experiment and we show that we are provided with a better estimate of the power spectra, in particular the error bars of the BB spectrum are smaller up to 20% for low multipoles. We point out the general validity of the new method. A possible future application is the LSPE balloon experiment, devoted to the observation of polarization at large angular scales.

Positional dependence of scale size and shape in butterfly wings: wing-wide phenotypic coordination of color-pattern elements and background.

PubMed

Kusaba, Kiseki; Otaki, Joji M

2009-02-01

Butterfly wing color-patterns are a phenotypically coordinated array of scales whose color is determined as cellular interpretation outputs for morphogenic signals. Here we investigated distribution patterns of scale shape and size in relation to position and coloration on the hindwings of a nymphalid butterfly Junonia orithya. Most scales had a smooth edge but scales at and near the natural and ectopic eyespot foci and in the postbasal area were jagged. Scale size decreased regularly from the postbasal to distal areas, and eyespots occasionally had larger scales than the background. Reasonable correlations were obtained between the eyespot size and focal scale size in females. Histological and real-time individual observations of the color-pattern developmental sequence showed that the background brown and blue colors expanded from the postbasal to distal areas independently from the color-pattern elements such as eyespots. These data suggest that morphogenic signals for coloration directly or indirectly influence the scale shape and size and that the blue "background" is organized by a long-range signal from an unidentified organizing center in J. orithya.

Memory Maintenance in Synapses with Calcium-Based Plasticity in the Presence of Background Activity

PubMed Central

Higgins, David; Graupner, Michael; Brunel, Nicolas

2014-01-01

Most models of learning and memory assume that memories are maintained in neuronal circuits by persistent synaptic modifications induced by specific patterns of pre- and postsynaptic activity. For this scenario to be viable, synaptic modifications must survive the ubiquitous ongoing activity present in neural circuits in vivo. In this paper, we investigate the time scales of memory maintenance in a calcium-based synaptic plasticity model that has been shown recently to be able to fit different experimental data-sets from hippocampal and neocortical preparations. We find that in the presence of background activity on the order of 1 Hz parameters that fit pyramidal layer 5 neocortical data lead to a very fast decay of synaptic efficacy, with time scales of minutes. We then identify two ways in which this memory time scale can be extended: (i) the extracellular calcium concentration in the experiments used to fit the model are larger than estimated concentrations in vivo. Lowering extracellular calcium concentration to in vivo levels leads to an increase in memory time scales of several orders of magnitude; (ii) adding a bistability mechanism so that each synapse has two stable states at sufficiently low background activity leads to a further boost in memory time scale, since memory decay is no longer described by an exponential decay from an initial state, but by an escape from a potential well. We argue that both features are expected to be present in synapses in vivo. These results are obtained first in a single synapse connecting two independent Poisson neurons, and then in simulations of a large network of excitatory and inhibitory integrate-and-fire neurons. Our results emphasise the need for studying plasticity at physiological extracellular calcium concentration, and highlight the role of synaptic bi- or multistability in the stability of learned synaptic structures. PMID:25275319

Background Signal as an in Situ Predictor of Dopamine Oxidation Potential: Improving Interpretation of Fast-Scan Cyclic Voltammetry Data.

PubMed

Meunier, Carl J; Roberts, James G; McCarty, Gregory S; Sombers, Leslie A

2017-02-15

Background-subtracted fast-scan cyclic voltammetry (FSCV) has emerged as a powerful analytical technique for monitoring subsecond molecular fluctuations in live brain tissue. Despite increasing utilization of FSCV, efforts to improve the accuracy of quantification have been limited due to the complexity of the technique and the dynamic recording environment. It is clear that variable electrode performance renders calibration necessary for accurate quantification; however, the nature of in vivo measurements can make conventional postcalibration difficult, or even impossible. Analyte-specific voltammograms and scaling factors that are critical for quantification can shift or fluctuate in vivo. This is largely due to impedance changes, and the effects of impedance on these measurements have not been characterized. We have previously reported that the background current can be used to predict electrode-specific scaling factors in situ. In this work, we employ model circuits to investigate the impact of impedance on FSCV measurements. Additionally, we take another step toward in situ electrode calibration by using the oxidation potential of quinones on the electrode surface to accurately predict the oxidation potential for dopamine at any point in an electrochemical experiment, as both are dependent on impedance. The model, validated both in adrenal slice and live brain tissue, enables information encoded in the shape of the background voltammogram to determine electrochemical parameters that are critical for accurate quantification. This improves data interpretation and provides a significant next step toward more automated methods for in vivo data analysis.

Attribution of ionospheric vertical plasma drift perturbations to large-scale waves and the dependence on solar activity (Invited)

NASA Astrophysics Data System (ADS)

Liu, H.; Richmond, A. D.

2013-12-01

In this study we quantify the contribution of individual large-scale waves to ionospheric electrodynamics, and examine the dependence of the ionospheric perturbations on solar activity. We focus on migrating diurnal tide (DW1) plus mean winds, migrating semidiurnal tide (SW2), quasi-stationary planetary wave 1 (QSPW1), and nonmigrating semidiurnal westward wave 1 (SW1) under northern winter conditions, when QSPW1 and SW1 are climatologically strong. From TIME-GCM simulations under solar minimum conditions, we calculate equatorial vertical ExB drifts due to mean winds and DW1, SW2, SW1 and QSPW1. In particular, wind components of both SW2 and SW1 become large at mid to high latitudes in the E-region, and kernel functions obtained from numerical experiments reveal that they can significantly affect the equatorial ion drift, likely through modulating the E-region wind dynamo. The most evident changes of total ionospheric vertical drift when solar activity is increased are seen around dawn and dusk, reflecting the more dominant role of large F-region Pedersen conductivity and of the F-region dynamo under high solar activity. Therefore, the lower atmosphere driving of the ionospheric variability is more evident under solar minimum conditions, not only because variability is more identifiable in a quieter background, but also because the E-region wind dynamo is more significant. These numerical experiments also demonstrate that the amplitudes, phases and latitudinal and vertical structures of large-scale waves are important in quantifying the ionospheric responses.

Parameterized post-Newtonian cosmology

NASA Astrophysics Data System (ADS)

Sanghai, Viraj A. A.; Clifton, Timothy

2017-03-01

Einstein’s theory of gravity has been extensively tested on solar system scales, and for isolated astrophysical systems, using the perturbative framework known as the parameterized post-Newtonian (PPN) formalism. This framework is designed for use in the weak-field and slow-motion limit of gravity, and can be used to constrain a large class of metric theories of gravity with data collected from the aforementioned systems. Given the potential of future surveys to probe cosmological scales to high precision, it is a topic of much contemporary interest to construct a similar framework to link Einstein’s theory of gravity and its alternatives to observations on cosmological scales. Our approach to this problem is to adapt and extend the existing PPN formalism for use in cosmology. We derive a set of equations that use the same parameters to consistently model both weak fields and cosmology. This allows us to parameterize a large class of modified theories of gravity and dark energy models on cosmological scales, using just four functions of time. These four functions can be directly linked to the background expansion of the universe, first-order cosmological perturbations, and the weak-field limit of the theory. They also reduce to the standard PPN parameters on solar system scales. We illustrate how dark energy models and scalar-tensor and vector-tensor theories of gravity fit into this framework, which we refer to as ‘parameterized post-Newtonian cosmology’ (PPNC).

Imitating intrinsic alignments: a bias to the CMB lensing-galaxy shape cross-correlation power spectrum induced by the large-scale structure bispectrum

NASA Astrophysics Data System (ADS)

Merkel, Philipp M.; Schäfer, Björn Malte

2017-10-01

Cross-correlating the lensing signals of galaxies and comic microwave background (CMB) fluctuations is expected to provide valuable cosmological information. In particular, it may help tighten constraints on parameters describing the properties of intrinsically aligned galaxies at high redshift. To access the information conveyed by the cross-correlation signal, its accurate theoretical description is required. We compute the bias to CMB lensing-galaxy shape cross-correlation measurements induced by non-linear structure growth. Using tree-level perturbation theory for the large-scale structure bispectrum, we find that the bias is negative on most angular scales, therefore mimicking the signal of intrinsic alignments. Combining Euclid-like galaxy lensing data with a CMB experiment comparable to the Planck satellite mission, the bias becomes significant only on smallest scales (ℓ ≳ 2500). For improved CMB observations, however, the corrections amount to 10-15 per cent of the CMB lensing-intrinsic alignment signal over a wide multipole range (10 ≲ ℓ ≲ 2000). Accordingly, the power spectrum bias, if uncorrected, translates into 2σ and 3σ errors in the determination of the intrinsic alignment amplitude in the case of CMB stage III and stage IV experiments, respectively.

Primordial Magnetic Field Effects on the CMB and Large-Scale Structure

DOE PAGES

Yamazaki, Dai G.; Ichiki, Kiyotomo; Kajino, Toshitaka; ...

2010-01-01

Mmore » agnetic fields are everywhere in nature, and they play an important role in every astronomical environment which involves the formation of plasma and currents. It is natural therefore to suppose that magnetic fields could be present in the turbulent high-temperature environment of the big bang. Such a primordial magnetic field (PF) would be expected to manifest itself in the cosmic microwave background (CB) temperature and polarization anisotropies, and also in the formation of large-scale structure. In this paper, we summarize the theoretical framework which we have developed to calculate the PF power spectrum to high precision. Using this formulation, we summarize calculations of the effects of a PF which take accurate quantitative account of the time evolution of the cutoff scale. We review the constructed numerical program, which is without approximation, and an improvement over the approach used in a number of previous works for studying the effect of the PF on the cosmological perturbations. We demonstrate how the PF is an important cosmological physical process on small scales. We also summarize the current constraints on the PF amplitude B λ and the power spectral index n B which have been deduced from the available CB observational data by using our computational framework.« less

Postprocessing Algorithm for Driving Conventional Scanning Tunneling Microscope at Fast Scan Rates

PubMed Central

Zhang, Hao; Li, Xianqi; Park, Jewook; Li, An-Ping

2017-01-01

We present an image postprocessing framework for Scanning Tunneling Microscope (STM) to reduce the strong spurious oscillations and scan line noise at fast scan rates and preserve the features, allowing an order of magnitude increase in the scan rate without upgrading the hardware. The proposed method consists of two steps for large scale images and four steps for atomic scale images. For large scale images, we first apply for each line an image registration method to align the forward and backward scans of the same line. In the second step we apply a “rubber band” model which is solved by a novel Constrained Adaptive and Iterative Filtering Algorithm (CIAFA). The numerical results on measurement from copper(111) surface indicate the processed images are comparable in accuracy to data obtained with a slow scan rate, but are free of the scan drift error commonly seen in slow scan data. For atomic scale images, an additional first step to remove line-by-line strong background fluctuations and a fourth step of replacing the postprocessed image by its ranking map as the final atomic resolution image are required. The resulting image restores the lattice image that is nearly undetectable in the original fast scan data. PMID:29362664

New type of hill-top inflation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barvinsky, A.O.; Department of Physics, Tomsk State University,Lenin Ave. 36, Tomsk 634050; Department of Physics and Astronomy, Pacific Institue for Theoretical Physics,University of British Columbia, 6224 Agricultural Road, Vancouver, BC V6T 1Z1

2016-01-20

We suggest a new type of hill-top inflation originating from the initial conditions in the form of the microcanonical density matrix for the cosmological model with a large number of quantum fields conformally coupled to gravity. Initial conditions for inflation are set up by cosmological instantons describing underbarrier oscillations in the vicinity of the inflaton potential maximum. These periodic oscillations of the inflaton field and cosmological scale factor are obtained within the approximation of two coupled oscillators subject to the slow roll regime in the Euclidean time. This regime is characterized by rapid oscillations of the scale factor on themore » background of a slowly varying inflaton, which guarantees smallness of slow roll parameters ϵ and η of the following inflation stage. A hill-like shape of the inflaton potential is shown to be generated by logarithmic loop corrections to the tree-level asymptotically shift-invariant potential in the non-minimal Higgs inflation model and R{sup 2}-gravity. The solution to the problem of hierarchy between the Planckian scale and the inflation scale is discussed within the concept of conformal higher spin fields, which also suggests the mechanism bringing the model below the gravitational cutoff and, thus, protecting it from large graviton loop corrections.« less

New type of hill-top inflation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barvinsky, A.O.; Nesterov, D.V.; Kamenshchik, A.Yu., E-mail: barvin@td.lpi.ru, E-mail: Alexander.Kamenshchik@bo.infn.it, E-mail: nesterov@td.lpi.ru

2016-01-01

We suggest a new type of hill-top inflation originating from the initial conditions in the form of the microcanonical density matrix for the cosmological model with a large number of quantum fields conformally coupled to gravity. Initial conditions for inflation are set up by cosmological instantons describing underbarrier oscillations in the vicinity of the inflaton potential maximum. These periodic oscillations of the inflaton field and cosmological scale factor are obtained within the approximation of two coupled oscillators subject to the slow roll regime in the Euclidean time. This regime is characterized by rapid oscillations of the scale factor on themore » background of a slowly varying inflaton, which guarantees smallness of slow roll parameters ε and η of the following inflation stage. A hill-like shape of the inflaton potential is shown to be generated by logarithmic loop corrections to the tree-level asymptotically shift-invariant potential in the non-minimal Higgs inflation model and R{sup 2}-gravity. The solution to the problem of hierarchy between the Planckian scale and the inflation scale is discussed within the concept of conformal higher spin fields, which also suggests the mechanism bringing the model below the gravitational cutoff and, thus, protecting it from large graviton loop corrections.« less

Measurement of kT splitting scales in W→ℓν events at [Formula: see text] with the ATLAS detector.

PubMed

Aad, G; Abajyan, T; Abbott, B; Abdallah, J; Abdel Khalek, S; Abdelalim, A A; Abdinov, O; Aben, R; Abi, B; Abolins, M; AbouZeid, O S; Abramowicz, H; Abreu, H; Acharya, B S; Adamczyk, L; Adams, D L; Addy, T N; Adelman, J; Adomeit, S; Adragna, P; Adye, T; Aefsky, S; Aguilar-Saavedra, J A; Agustoni, M; Ahlen, S P; Ahles, F; Ahmad, A; Ahsan, M; Aielli, G; Åkesson, T P A; Akimoto, G; Akimov, A V; Alam, M A; Albert, J; Albrand, S; Aleksa, M; Aleksandrov, I N; Alessandria, F; Alexa, C; Alexander, G; Alexandre, G; Alexopoulos, T; Alhroob, M; Aliev, M; Alimonti, G; Alison, J; Allbrooke, B M M; Allison, L J; Allport, P P; Allwood-Spiers, S E; Almond, J; Aloisio, A; Alon, R; Alonso, A; Alonso, F; Altheimer, A; Alvarez Gonzalez, B; Alviggi, M G; Amako, K; Amelung, C; Ammosov, V V; Amor Dos Santos, S P; Amorim, A; Amoroso, S; Amram, N; Anastopoulos, C; Ancu, L S; Andari, N; Andeen, T; Anders, C F; Anders, G; Anderson, K J; Andreazza, A; Andrei, V; Anduaga, X S; Angelidakis, S; Anger, P; Angerami, A; Anghinolfi, F; Anisenkov, A; Anjos, N; Annovi, A; Antonaki, A; Antonelli, M; Antonov, A; Antos, J; Anulli, F; Aoki, M; Aperio Bella, L; Apolle, R; Arabidze, G; Aracena, I; Arai, Y; Arce, A T H; Arfaoui, S; Arguin, J-F; Argyropoulos, S; Arik, E; Arik, M; Armbruster, A J; Arnaez, O; Arnal, V; Artamonov, A; Artoni, G; Arutinov, D; Asai, S; Ask, S; Åsman, B; Asquith, L; Assamagan, K; Astalos, R; Astbury, A; Atkinson, M; Auerbach, B; Auge, E; Augsten, K; Aurousseau, M; Avolio, G; Axen, D; Azuelos, G; Azuma, Y; Baak, M A; Baccaglioni, G; Bacci, C; Bach, A M; Bachacou, H; Bachas, K; Backes, M; Backhaus, M; Backus Mayes, J; Badescu, E; Bagnaia, P; Bai, Y; Bailey, D C; Bain, T; Baines, J T; Baker, O K; Baker, S; Balek, P; Balli, F; Banas, E; Banerjee, P; Banerjee, Sw; Banfi, D; Bangert, A; Bansal, V; Bansil, H S; Barak, L; Baranov, S P; Barber, T; Barberio, E L; Barberis, D; Barbero, M; Bardin, D Y; Barillari, T; Barisonzi, M; Barklow, T; Barlow, N; Barnett, B M; Barnett, R M; Baroncelli, A; Barone, G; Barr, A J; Barreiro, F; Barreiro Guimarães da Costa, J; Bartoldus, R; Barton, A E; Bartsch, V; Basye, A; Bates, R L; Batkova, L; Batley, J R; Battaglia, A; Battistin, M; Bauer, F; Bawa, H S; Beale, S; Beau, T; Beauchemin, P H; Beccherle, R; Bechtle, P; Beck, H P; Becker, K; Becker, S; Beckingham, M; Becks, K H; Beddall, A J; Beddall, A; Bedikian, S; Bednyakov, V A; Bee, C P; Beemster, L J; Beermann, T A; Begel, M; Behar Harpaz, S; Belanger-Champagne, C; Bell, P J; Bell, W H; Bella, G; Bellagamba, L; Bellomo, M; Belloni, A; Beloborodova, O; Belotskiy, K; Beltramello, O; Benary, O; Benchekroun, D; Bendtz, K; Benekos, N; Benhammou, Y; Benhar Noccioli, E; Benitez Garcia, J A; Benjamin, D P; Benoit, M; Bensinger, J R; Benslama, K; Bentvelsen, S; Berge, D; Bergeaas Kuutmann, E; Berger, N; Berghaus, F; Berglund, E; Beringer, J; Bernat, P; Bernhard, R; Bernius, C; Bernlochner, F U; Berry, T; Bertella, C; Bertin, A; Bertolucci, F; Besana, M I; Besjes, G J; Besson, N; Bethke, S; Bhimji, W; Bianchi, R M; Bianchini, L; Bianco, M; Biebel, O; Bieniek, S P; Bierwagen, K; Biesiada, J; Biglietti, M; Bilokon, H; Bindi, M; Binet, S; Bingul, A; Bini, C; Biscarat, C; Bittner, B; Black, C W; Black, J E; Black, K M; Blair, R E; Blanchard, J-B; Blazek, T; Bloch, I; Blocker, C; Blocki, J; Blum, W; Blumenschein, U; Bobbink, G J; Bobrovnikov, V S; Bocchetta, S S; Bocci, A; Boddy, C R; Boehler, M; Boek, J; Boek, T T; Boelaert, N; Bogaerts, J A; Bogdanchikov, A; Bogouch, A; Bohm, C; Bohm, J; Boisvert, V; Bold, T; Boldea, V; Bolnet, N M; Bomben, M; Bona, M; Boonekamp, M; Bordoni, S; Borer, C; Borisov, A; Borissov, G; Borjanovic, I; Borri, M; Borroni, S; Bortfeldt, J; Bortolotto, V; Bos, K; Boscherini, D; Bosman, M; Boterenbrood, H; Bouchami, J; Boudreau, J; Bouhova-Thacker, E V; Boumediene, D; Bourdarios, C; Bousson, N; Boutouil, S; Boveia, A; Boyd, J; Boyko, I R; Bozovic-Jelisavcic, I; Bracinik, J; Branchini, P; Brandt, A; Brandt, G; Brandt, O; Bratzler, U; Brau, B; Brau, J E; Braun, H M; Brazzale, S F; Brelier, B; Bremer, J; Brendlinger, K; Brenner, R; Bressler, S; Bristow, T M; Britton, D; Brochu, F M; Brock, I; Brock, R; Broggi, F; Bromberg, C; Bronner, J; Brooijmans, G; Brooks, T; Brooks, W K; Brown, G; Bruckman de Renstrom, P A; Bruncko, D; Bruneliere, R; Brunet, S; Bruni, A; Bruni, G; Bruschi, M; Bryngemark, L; Buanes, T; Buat, Q; Bucci, F; Buchanan, J; Buchholz, P; Buckingham, R M; Buckley, A G; Buda, S I; Budagov, I A; Budick, B; Bugge, L; Bulekov, O; Bundock, A C; Bunse, M; Buran, T; Burckhart, H; Burdin, S; Burgess, T; Burke, S; Busato, E; Büscher, V; Bussey, P; Buszello, C P; Butler, B; Butler, J M; Buttar, C M; Butterworth, J M; Buttinger, W; Byszewski, M; Cabrera Urbán, S; Caforio, D; Cakir, O; Calafiura, P; Calderini, G; Calfayan, P; Calkins, R; Caloba, L P; Caloi, R; Calvet, D; Calvet, S; Camacho Toro, R; Camarri, P; Cameron, D; Caminada, L M; Caminal Armadans, R; Campana, S; Campanelli, M; Canale, V; Canelli, F; Canepa, A; Cantero, J; Cantrill, R; Cao, T; Capeans Garrido, M D M; Caprini, I; Caprini, M; Capriotti, D; Capua, M; Caputo, R; Cardarelli, R; Carli, T; Carlino, G; Carminati, L; Caron, S; Carquin, E; Carrillo-Montoya, G D; Carter, A A; Carter, J R; Carvalho, J; Casadei, D; Casado, M P; Cascella, M; Caso, C; Castaneda-Miranda, E; Castillo Gimenez, V; Castro, N F; Cataldi, G; Catastini, P; Catinaccio, A; Catmore, J R; Cattai, A; Cattani, G; Caughron, S; Cavaliere, V; Cavalleri, P; Cavalli, D; Cavalli-Sforza, M; Cavasinni, V; Ceradini, F; Cerqueira, A S; Cerri, A; Cerrito, L; Cerutti, F; Cetin, S A; Chafaq, A; Chakraborty, D; Chalupkova, I; Chan, K; Chang, P; Chapleau, B; Chapman, J D; Chapman, J W; Charlton, D G; Chavda, V; Chavez Barajas, C A; Cheatham, S; Chekanov, S; Chekulaev, S V; Chelkov, G A; Chelstowska, M A; Chen, C; Chen, H; Chen, S; Chen, X; Chen, Y; Cheng, Y; Cheplakov, A; Cherkaoui El Moursli, R; Chernyatin, V; Cheu, E; Cheung, S L; Chevalier, L; Chiefari, G; Chikovani, L; Childers, J T; Chilingarov, A; Chiodini, G; Chisholm, A S; Chislett, R T; Chitan, A; Chizhov, M V; Choudalakis, G; Chouridou, S; Chow, B K B; Christidi, I A; Christov, A; Chromek-Burckhart, D; Chu, M L; Chudoba, J; Ciapetti, G; Ciftci, A K; Ciftci, R; Cinca, D; Cindro, V; Ciocio, A; Cirilli, M; Cirkovic, P; Citron, Z H; Citterio, M; Ciubancan, M; Clark, A; Clark, P J; Clarke, R N; Cleland, W; Clemens, J C; Clement, B; Clement, C; Coadou, Y; Cobal, M; Coccaro, A; Cochran, J; Coffey, L; Cogan, J G; Coggeshall, J; Colas, J; Cole, S; Colijn, A P; Collins, N J; Collins-Tooth, C; Collot, J; Colombo, T; Colon, G; Compostella, G; Conde Muiño, P; Coniavitis, E; Conidi, M C; Consonni, S M; Consorti, V; Constantinescu, S; Conta, C; Conti, G; Conventi, F; Cooke, M; Cooper, B D; Cooper-Sarkar, A M; Cooper-Smith, N J; Copic, K; Cornelissen, T; Corradi, M; Corriveau, F; Cortes-Gonzalez, A; Cortiana, G; Costa, G; Costa, M J; Costanzo, D; Côté, D; Cottin, G; Courneyea, L; Cowan, G; Cox, B E; Cranmer, K; Crépé-Renaudin, S; Crescioli, F; Cristinziani, M; Crosetti, G; Cuciuc, C-M; Cuenca Almenar, C; Cuhadar Donszelmann, T; Cummings, J; Curatolo, M; Curtis, C J; Cuthbert, C; Cwetanski, P; Czirr, H; Czodrowski, P; Czyczula, Z; D'Auria, S; D'Onofrio, M; D'Orazio, A; Da Cunha Sargedas De Sousa, M J; Da Via, C; Dabrowski, W; Dafinca, A; Dai, T; Dallaire, F; Dallapiccola, C; Dam, M; Damiani, D S; Danielsson, H O; Dao, V; Darbo, G; Darlea, G L; Darmora, S; Dassoulas, J A; Davey, W; Davidek, T; Davidson, N; Davidson, R; Davies, E; Davies, M; Davignon, O; Davison, A R; Davygora, Y; Dawe, E; Dawson, I; Daya-Ishmukhametova, R K; De, K; de Asmundis, R; De Castro, S; De Cecco, S; de Graat, J; De Groot, N; de Jong, P; De La Taille, C; De la Torre, H; De Lorenzi, F; De Nooij, L; De Pedis, D; De Salvo, A; De Sanctis, U; De Santo, A; De Vivie De Regie, J B; De Zorzi, G; Dearnaley, W J; Debbe, R; Debenedetti, C; Dechenaux, B; Dedovich, D V; Degenhardt, J; Del Peso, J; Del Prete, T; Delemontex, T; Deliyergiyev, M; Dell'Acqua, A; Dell'Asta, L; Della Pietra, M; Della Volpe, D; Delmastro, M; 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A measurement of splitting scales, as defined by the k T clustering algorithm, is presented for final states containing a W boson produced in proton-proton collisions at a centre-of-mass energy of 7 TeV. The measurement is based on the full 2010 data sample corresponding to an integrated luminosity of 36 pb -1 which was collected using the ATLAS detector at the CERN Large Hadron Collider. Cluster splitting scales are measured in events containing W bosons decaying to electrons or muons. The measurement comprises the four hardest splitting scales in a k T cluster sequence of the hadronic activity accompanying the W boson, and ratios of these splitting scales. Backgrounds such as multi-jet and top-quark-pair production are subtracted and the results are corrected for detector effects. Predictions from various Monte Carlo event generators at particle level are compared to the data. Overall, reasonable agreement is found with all generators, but larger deviations between the predictions and the data are evident in the soft regions of the splitting scales.

Planck 2015 results. XVI. Isotropy and statistics of the CMB

NASA Astrophysics Data System (ADS)

Planck Collaboration; Ade, P. A. R.; Aghanim, N.; Akrami, Y.; Aluri, P. K.; Arnaud, M.; Ashdown, M.; Aumont, J.; Baccigalupi, C.; 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.; Casaponsa, B.; 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.; Contreras, D.; Couchot, F.; Coulais, A.; Crill, B. P.; Cruz, M.; 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.; Fantaye, Y.; Fergusson, J.; Fernandez-Cobos, R.; Finelli, F.; Forni, O.; Frailis, M.; Fraisse, A. A.; Franceschi, E.; Frejsel, A.; Frolov, 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.; Hansen, F. K.; Hanson, D.; Harrison, D. L.; 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.; Lagache, G.; Lähteenmäki, A.; Lamarre, J.-M.; Lasenby, A.; Lattanzi, M.; Lawrence, C. R.; Leonardi, R.; Lesgourgues, J.; Levrier, F.; Liguori, M.; Lilje, P. B.; Linden-Vørnle, M.; Liu, H.; 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.; Mikkelsen, K.; Mitra, S.; Miville-Deschênes, M.-A.; Molinari, D.; Moneti, A.; Montier, L.; Morgante, G.; Mortlock, D.; Moss, A.; 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.; Pant, N.; Paoletti, D.; Pasian, F.; Patanchon, G.; Pearson, T. J.; 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.; Rebolo, R.; Reinecke, M.; Remazeilles, M.; Renault, C.; Renzi, A.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Rossetti, M.; Rotti, A.; 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.; Souradeep, T.; Spencer, L. D.; Stolyarov, V.; Stompor, R.; Sudiwala, R.; Sunyaev, R.; Sutton, D.; Suur-Uski, A.-S.; Sygnet, J.-F.; Tauber, J. A.; Terenzi, L.; Toffolatti, L.; Tomasi, M.; Tristram, M.; Trombetti, T.; 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.; Zibin, J. P.; Zonca, A.

2016-09-01

We test the statistical isotropy and Gaussianity of the cosmic microwave background (CMB) anisotropies using observations made by the Planck satellite. Our results are based mainly on the full Planck mission for temperature, but also include some polarization measurements. In particular, we consider the CMB anisotropy maps derived from the multi-frequency Planck data by several component-separation methods. For the temperature anisotropies, we find excellent agreement between results based on these sky maps over both a very large fraction of the sky and a broad range of angular scales, establishing that potential foreground residuals do not affect our studies. Tests of skewness, kurtosis, multi-normality, N-point functions, and Minkowski functionals indicate consistency with Gaussianity, while a power deficit at large angular scales is manifested in several ways, for example low map variance. The results of a peak statistics analysis are consistent with the expectations of a Gaussian random field. The "Cold Spot" is detected with several methods, including map kurtosis, peak statistics, and mean temperature profile. We thoroughly probe the large-scale dipolar power asymmetry, detecting it with several independent tests, and address the subject of a posteriori correction. Tests of directionality suggest the presence of angular clustering from large to small scales, but at a significance that is dependent on the details of the approach. We perform the first examination of polarization data, finding the morphology of stacked peaks to be consistent with the expectations of statistically isotropic simulations. Where they overlap, these results are consistent with the Planck 2013 analysis based on the nominal mission data and provide our most thorough view of the statistics of the CMB fluctuations to date.

Mechanisms of diurnal precipitation over the US Great Plains: a cloud resolving model perspective

NASA Astrophysics Data System (ADS)

Lee, Myong-In; Choi, Ildae; Tao, Wei-Kuo; Schubert, Siegfried D.; Kang, In-Sik

2010-02-01

The mechanisms of summertime diurnal precipitation in the US Great Plains were examined with the two-dimensional (2D) Goddard Cumulus Ensemble (GCE) cloud-resolving model (CRM). The model was constrained by the observed large-scale background state and surface flux derived from the Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Program’s Intensive Observing Period (IOP) data at the Southern Great Plains (SGP). The model, when continuously-forced by realistic surface flux and large-scale advection, simulates reasonably well the temporal evolution of the observed rainfall episodes, particularly for the strongly forced precipitation events. However, the model exhibits a deficiency for the weakly forced events driven by diurnal convection. Additional tests were run with the GCE model in order to discriminate between the mechanisms that determine daytime and nighttime convection. In these tests, the model was constrained with the same repeating diurnal variation in the large-scale advection and/or surface flux. The results indicate that it is primarily the surface heat and moisture flux that is responsible for the development of deep convection in the afternoon, whereas the large-scale upward motion and associated moisture advection play an important role in preconditioning nocturnal convection. In the nighttime, high clouds are continuously built up through their interaction and feedback with long-wave radiation, eventually initiating deep convection from the boundary layer. Without these upper-level destabilization processes, the model tends to produce only daytime convection in response to boundary layer heating. This study suggests that the correct simulation of the diurnal variation in precipitation requires that the free-atmospheric destabilization mechanisms resolved in the CRM simulation must be adequately parameterized in current general circulation models (GCMs) many of which are overly sensitive to the parameterized boundary layer heating.

Mechanisms of Diurnal Precipitation over the United States Great Plains: A Cloud-Resolving Model Simulation

NASA Technical Reports Server (NTRS)

Lee, M.-I.; Choi, I.; Tao, W.-K.; Schubert, S. D.; Kang, I.-K.

2010-01-01

The mechanisms of summertime diurnal precipitation in the US Great Plains were examined with the two-dimensional (2D) Goddard Cumulus Ensemble (GCE) cloud-resolving model (CRM). The model was constrained by the observed large-scale background state and surface flux derived from the Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Program s Intensive Observing Period (IOP) data at the Southern Great Plains (SGP). The model, when continuously-forced by realistic surface flux and large-scale advection, simulates reasonably well the temporal evolution of the observed rainfall episodes, particularly for the strongly forced precipitation events. However, the model exhibits a deficiency for the weakly forced events driven by diurnal convection. Additional tests were run with the GCE model in order to discriminate between the mechanisms that determine daytime and nighttime convection. In these tests, the model was constrained with the same repeating diurnal variation in the large-scale advection and/or surface flux. The results indicate that it is primarily the surface heat and moisture flux that is responsible for the development of deep convection in the afternoon, whereas the large-scale upward motion and associated moisture advection play an important role in preconditioning nocturnal convection. In the nighttime, high clouds are continuously built up through their interaction and feedback with long-wave radiation, eventually initiating deep convection from the boundary layer. Without these upper-level destabilization processes, the model tends to produce only daytime convection in response to boundary layer heating. This study suggests that the correct simulation of the diurnal variation in precipitation requires that the free-atmospheric destabilization mechanisms resolved in the CRM simulation must be adequately parameterized in current general circulation models (GCMs) many of which are overly sensitive to the parameterized boundary layer heating.

Planck 2015 results: XVI. Isotropy and statistics of the CMB

DOE PAGES

Ade, P. A. R.; Aghanim, N.; Akrami, Y.; ...

2016-09-20

In this paper, we test the statistical isotropy and Gaussianity of the cosmic microwave background (CMB) anisotropies using observations made by the Planck satellite. Our results are based mainly on the full Planck mission for temperature, but also include some polarization measurements. In particular, we consider the CMB anisotropy maps derived from the multi-frequency Planck data by several component-separation methods. For the temperature anisotropies, we find excellent agreement between results based on these sky maps over both a very large fraction of the sky and a broad range of angular scales, establishing that potential foreground residuals do not affect ourmore » studies. Tests of skewness, kurtosis, multi-normality, N-point functions, and Minkowski functionals indicate consistency with Gaussianity, while a power deficit at large angular scales is manifested in several ways, for example low map variance. The results of a peak statistics analysis are consistent with the expectations of a Gaussian random field. The “Cold Spot” is detected with several methods, including map kurtosis, peak statistics, and mean temperature profile. We thoroughly probe the large-scale dipolar power asymmetry, detecting it with several independent tests, and address the subject of a posteriori correction. Tests of directionality suggest the presence of angular clustering from large to small scales, but at a significance that is dependent on the details of the approach. We perform the first examination of polarization data, finding the morphology of stacked peaks to be consistent with the expectations of statistically isotropic simulations. Finally, where they overlap, these results are consistent with the Planck 2013 analysis based on the nominal mission data and provide our most thorough view of the statistics of the CMB fluctuations to date.« less

Planck data versus large scale structure: Methods to quantify discordance

NASA Astrophysics Data System (ADS)

Charnock, Tom; Battye, Richard A.; Moss, Adam

2017-06-01

Discordance in the Λ cold dark matter cosmological model can be seen by comparing parameters constrained by cosmic microwave background (CMB) measurements to those inferred by probes of large scale structure. Recent improvements in observations, including final data releases from both Planck and SDSS-III BOSS, as well as improved astrophysical uncertainty analysis of CFHTLenS, allows for an update in the quantification of any tension between large and small scales. This paper is intended, primarily, as a discussion on the quantifications of discordance when comparing the parameter constraints of a model when given two different data sets. We consider Kullback-Leibler divergence, comparison of Bayesian evidences and other statistics which are sensitive to the mean, variance and shape of the distributions. However, as a byproduct, we present an update to the similar analysis in [R. A. Battye, T. Charnock, and A. Moss, Phys. Rev. D 91, 103508 (2015), 10.1103/PhysRevD.91.103508], where we find that, considering new data and treatment of priors, the constraints from the CMB and from a combination of large scale structure (LSS) probes are in greater agreement and any tension only persists to a minor degree. In particular, we find the parameter constraints from the combination of LSS probes which are most discrepant with the Planck 2015 +Pol +BAO parameter distributions can be quantified at a ˜2.55 σ tension using the method introduced in [R. A. Battye, T. Charnock, and A. Moss, Phys. Rev. D 91, 103508 (2015), 10.1103/PhysRevD.91.103508]. If instead we use the distributions constrained by the combination of LSS probes which are in greatest agreement with those from Planck 2015 +Pol +BAO this tension is only 0.76 σ .

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ade, P. A. R.; Aghanim, N.; Akrami, Y.

In this paper, we test the statistical isotropy and Gaussianity of the cosmic microwave background (CMB) anisotropies using observations made by the Planck satellite. Our results are based mainly on the full Planck mission for temperature, but also include some polarization measurements. In particular, we consider the CMB anisotropy maps derived from the multi-frequency Planck data by several component-separation methods. For the temperature anisotropies, we find excellent agreement between results based on these sky maps over both a very large fraction of the sky and a broad range of angular scales, establishing that potential foreground residuals do not affect ourmore » studies. Tests of skewness, kurtosis, multi-normality, N-point functions, and Minkowski functionals indicate consistency with Gaussianity, while a power deficit at large angular scales is manifested in several ways, for example low map variance. The results of a peak statistics analysis are consistent with the expectations of a Gaussian random field. The “Cold Spot” is detected with several methods, including map kurtosis, peak statistics, and mean temperature profile. We thoroughly probe the large-scale dipolar power asymmetry, detecting it with several independent tests, and address the subject of a posteriori correction. Tests of directionality suggest the presence of angular clustering from large to small scales, but at a significance that is dependent on the details of the approach. We perform the first examination of polarization data, finding the morphology of stacked peaks to be consistent with the expectations of statistically isotropic simulations. Finally, where they overlap, these results are consistent with the Planck 2013 analysis based on the nominal mission data and provide our most thorough view of the statistics of the CMB fluctuations to date.« less

On the transition towards slow manifold in shallow-water and 3D Euler equations in a rotating frame

NASA Technical Reports Server (NTRS)

Mahalov, A.

1994-01-01

The long-time, asymptotic state of rotating homogeneous shallow-water equations is investigated. Our analysis is based on long-time averaged rotating shallow-water equations describing interactions of large-scale, horizontal, two-dimensional motions with surface inertial-gravity waves field for a shallow, uniformly rotating fluid layer. These equations are obtained in two steps: first by introducing a Poincare/Kelvin linear propagator directly into classical shallow-water equations, then by averaging. The averaged equations describe interaction of wave fields with large-scale motions on time scales long compared to the time scale 1/f(sub o) introduced by rotation (f(sub o)/2-angular velocity of background rotation). The present analysis is similar to the one presented by Waleffe (1991) for 3D Euler equations in a rotating frame. However, since three-wave interactions in rotating shallow-water equations are forbidden, the final equations describing the asymptotic state are simplified considerably. Special emphasis is given to a new conservation law found in the asymptotic state and decoupling of the dynamics of the divergence free part of the velocity field. The possible rising of a decoupled dynamics in the asymptotic state is also investigated for homogeneous turbulence subjected to a background rotation. In our analysis we use long-time expansion, where the velocity field is decomposed into the 'slow manifold' part (the manifold which is unaffected by the linear 'rapid' effects of rotation or the inertial waves) and a formal 3D disturbance. We derive the physical space version of the long-time averaged equations and consider an invariant, basis-free derivation. This formulation can be used to generalize Waleffe's (1991) helical decomposition to viscous inhomogeneous flows (e.g. problems in cylindrical geometry with no-slip boundary conditions on the cylinder surface and homogeneous in the vertical direction).

Influence of the Solar Cycle on Turbulence Properties and Cosmic-Ray Diffusion

NASA Astrophysics Data System (ADS)

Zhao, L.-L.; Adhikari, L.; Zank, G. P.; Hu, Q.; Feng, X. S.

2018-04-01

The solar cycle dependence of various turbulence quantities and cosmic-ray (CR) diffusion coefficients is investigated by using OMNI 1 minute resolution data over 22 years. We employ Elsässer variables z ± to calculate the magnetic field turbulence energy and correlation lengths for both the inwardly and outwardly directed interplanetary magnetic field (IMF). We present the temporal evolution of both large-scale solar wind (SW) plasma variables and small-scale magnetic fluctuations. Based on these observed quantities, we study the influence of solar activity on CR parallel and perpendicular diffusion using quasi-linear theory and nonlinear guiding center theory, respectively. We also evaluate the radial evolution of the CR diffusion coefficients by using the boundary conditions for different solar activity levels. We find that in the ecliptic plane at 1 au (1), the large-scale SW temperature T, velocity V sw, Alfvén speed V A , and IMF magnitude B 0 are positively related to solar activity; (2) the fluctuating magnetic energy density < {{z}+/- }2> , residual energy E D , and corresponding correlation functions all have an obvious solar cycle dependence. The residual energy E D is always negative, which indicates that the energy in magnetic fluctuations is larger than the energy in kinetic fluctuations, especially at solar maximum; (3) the correlation length λ for magnetic fluctuations does not show significant solar cycle variation; (4) the temporally varying shear source of turbulence, which is most important in the inner heliosphere, depends on the solar cycle; (5) small-scale fluctuations may not depend on the direction of the background magnetic field; and (6) high levels of SW fluctuations will increase CR perpendicular diffusion and decrease CR parallel diffusion, but this trend can be masked if the background IMF changes in concert with turbulence in response to solar activity. These results provide quantitative inputs for both turbulence transport models and CR diffusion models, and also provide valuable insight into the long-term modulation of CRs in the heliosphere.

VLSI (Very Large Scale Integrated Circuits) Design with the MacPitts Silicon Compiler.

DTIC Science & Technology

1985-09-01

the background. If the algorithm is not fully debugged, then issue instead macpitts basename herald so MacPitts diagnostics and Liszt diagnostics both...command interpreter. Upon compilation, however, the following LI!F compiler ( Liszt ) diagnostic results, Error: Non-number to minus nil where the first...language used in the MacPitts source code. The more instructive solution is to write the Franz LISP code to decide if a jumper wire is needed, and if so, to

Early Intervention to Reduce Alcohol Misuse and Abuse in the Ohio Army National Guard

DTIC Science & Technology

2016-09-01

Brittany Brownrigg, Data Coordinator at Case Western Reserve University, with the opportunity to work on a large-scale, multi-site, USAMRAA funded study ...CHCR have completed the intro video which will be posted on the app stores. The following meetings took place between study staff and OHARNG members...background/rationale, the design and methodology of the study and study progress as of that date. She also got their feedback on the first iteration of

Hot spots in the microwave sky

NASA Technical Reports Server (NTRS)

Vittorio, Nicola; Juszkiewicz, Roman

1987-01-01

Tha assumption that the cosmic background fluctuations can be approximated as a random Gaussian field implies specific predictions for the radiation temperature pattern. Using this assumption, the abundances and angular sizes are calculated for regions of various levels of brightness expected to appear in the sky. Different observational strategies are assessed in the context of these results. Calculations for both large-angle and small-angle anisotropy generated by scale-invariant fluctuations in a flat universe are presented. Also discussed are simple generalizations to open cosmological models.

Lensing of the CMB: non-Gaussian aspects.

PubMed

Zaldarriaga, M

2001-06-01

We compute the small angle limit of the three- and four-point function of the cosmic microwave background (CMB) temperature induced by the gravitational lensing effect by the large-scale structure of the universe. We relate the non-Gaussian aspects presented in this paper with those in our previous studies of the lensing effects. We interpret the statistics proposed in previous work in terms of different configurations of the four-point function and show how they relate to the statistic that maximizes the S/N.

On the formation and evolution of clumps of galaxies in an expanding universe

NASA Technical Reports Server (NTRS)

Norman, C. A.; Silk, J.

1978-01-01

Results are derived for the development of phase-space clumps of mass points in a background spectrum of gravitational-potential fluctuations. The Vlasov equation and the pair correlation equation (in the weak coupling limit) are solved exactly in an Einstein-de Sitter cosmology, and the plasma-clumping theory is used to identify terms that yield important collective effects. Various astrophysical implications are discussed, including the formation of large-scale inhomogeneity and the enhanced generation of correlations in the distribution of galaxies.

The large enriched germanium experiment for neutrinoless double beta decay (LEGEND)

NASA Astrophysics Data System (ADS)

Abgrall, N.; Abramov, A.; Abrosimov, N.; Abt, I.; Agostini, M.; Agartioglu, M.; Ajjaq, A.; Alvis, S. I.; Avignone, F. T.; Bai, X.; Balata, M.; Barabanov, I.; Barabash, A. S.; Barton, P. J.; Baudis, L.; Bezrukov, L.; Bode, T.; Bolozdynya, A.; Borowicz, D.; Boston, A.; Boston, H.; Boyd, S. T. P.; Breier, R.; Brudanin, V.; Brugnera, R.; Busch, M.; Buuck, M.; Caldwell, A.; Caldwell, T. S.; Camellato, T.; Carpenter, M.; Cattadori, C.; Cederkäll, J.; Chan, Y.-D.; Chen, S.; Chernogorov, A.; Christofferson, C. D.; Chu, P.-H.; Cooper, R. J.; Cuesta, C.; Demidova, E. V.; Deng, Z.; Deniz, M.; Detwiler, J. A.; Di Marco, N.; Domula, A.; Du, Q.; Efremenko, Yu.; Egorov, V.; Elliott, S. R.; Fields, D.; Fischer, F.; Galindo-Uribarri, A.; Gangapshev, A.; Garfagnini, A.; Gilliss, T.; Giordano, M.; Giovanetti, G. K.; Gold, M.; Golubev, P.; Gooch, C.; Grabmayr, P.; Green, M. P.; Gruszko, J.; Guinn, I. S.; Guiseppe, V. E.; Gurentsov, V.; Gurov, Y.; Gusev, K.; Hakenmüeller, J.; Harkness-Brennan, L.; Harvey, Z. R.; Haufe, C. R.; Hauertmann, L.; Heglund, D.; Hehn, L.; Heinz, A.; Hiller, R.; Hinton, J.; Hodak, R.; Hofmann, W.; Howard, S.; Howe, M. A.; Hult, M.; Inzhechik, L. V.; Csáthy, J. Janicskó; Janssens, R.; Ješkovský, M.; Jochum, J.; Johansson, H. T.; Judson, D.; Junker, M.; Kaizer, J.; Kang, K.; Kazalov, V.; Kermadic, Y.; Kiessling, F.; Kirsch, A.; Kish, A.; Klimenko, A.; Knöpfle, K. T.; Kochetov, O.; Konovalov, S. I.; Kontul, I.; Kornoukhov, V. N.; Kraetzschmar, T.; Kröninger, K.; Kumar, A.; Kuzminov, V. V.; Lang, K.; Laubenstein, M.; Lazzaro, A.; Li, Y. L.; Li, Y.-Y.; Li, H. B.; Lin, S. T.; Lindner, M.; Lippi, I.; Liu, S. K.; Liu, X.; Liu, J.; Loomba, D.; Lubashevskiy, A.; Lubsandorzhiev, B.; Lutter, G.; Ma, H.; Majorovits, B.; Mamedov, F.; Martin, R. D.; Massarczyk, R.; Matthews, J. A. J.; McFadden, N.; Mei, D.-M.; Mei, H.; Meijer, S. J.; Mengoni, D.; Mertens, S.; Miller, W.; Miloradovic, M.; Mingazheva, R.; Misiaszek, M.; Moseev, P.; Myslik, J.; Nemchenok, I.; Nilsson, T.; Nolan, P.; O'Shaughnessy, C.; Othman, G.; Panas, K.; Pandola, L.; Papp, L.; Pelczar, K.; Peterson, D.; Pettus, W.; Poon, A. W. P.; Povinec, P. P.; Pullia, A.; Quintana, X. C.; Radford, D. C.; Rager, J.; Ransom, C.; Recchia, F.; Reine, A. L.; Riboldi, S.; Rielage, K.; Rozov, S.; Rouf, N. W.; Rukhadze, E.; Rumyantseva, N.; Saakyan, R.; Sala, E.; Salamida, F.; Sandukovsky, V.; Savard, G.; Schönert, S.; Schütz, A.-K.; Schulz, O.; Schuster, M.; Schwingenheuer, B.; Selivanenko, O.; Sevda, B.; Shanks, B.; Shevchik, E.; Shirchenko, M.; Simkovic, F.; Singh, L.; Singh, V.; Skorokhvatov, M.; Smolek, K.; Smolnikov, A.; Sonay, A.; Spavorova, M.; Stekl, I.; Stukov, D.; Tedeschi, D.; Thompson, J.; Van Wechel, T.; Varner, R. L.; Vasenko, A. A.; Vasilyev, S.; Veresnikova, A.; Vetter, K.; von Sturm, K.; Vorren, K.; Wagner, M.; Wang, G.-J.; Waters, D.; Wei, W.-Z.; Wester, T.; White, B. R.; Wiesinger, C.; Wilkerson, J. F.; Willers, M.; Wiseman, C.; Wojcik, M.; Wong, H. T.; Wyenberg, J.; Xu, W.; Yakushev, E.; Yang, G.; Yu, C.-H.; Yue, Q.; Yumatov, V.; Zeman, J.; Zeng, Z.; Zhitnikov, I.; Zhu, B.; Zinatulina, D.; Zschocke, A.; Zsigmond, A. J.; Zuber, K.; Zuzel, G.

2017-10-01

The observation of neutrinoless double-beta decay (0νββ) would show that lepton number is violated, reveal that neu-trinos are Majorana particles, and provide information on neutrino mass. A discovery-capable experiment covering the inverted ordering region, with effective Majorana neutrino masses of 15 - 50 meV, will require a tonne-scale experiment with excellent energy resolution and extremely low backgrounds, at the level of ˜0.1 count /(FWHM.t.yr) in the region of the signal. The current generation 76Ge experiments GERDA and the Majorana Demonstrator, utilizing high purity Germanium detectors with an intrinsic energy resolution of 0.12%, have achieved the lowest backgrounds by over an order of magnitude in the 0νββ signal region of all 0νββ experiments. Building on this success, the LEGEND collaboration has been formed to pursue a tonne-scale 76Ge experiment. The collaboration aims to develop a phased 0νββ experimental program with discovery potential at a half-life approaching or at 1028 years, using existing resources as appropriate to expedite physics results.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guo, X.; Florinski, V.

We present a new model that couples galactic cosmic-ray (GCR) propagation with magnetic turbulence transport and the MHD background evolution in the heliosphere. The model is applied to the problem of the formation of corotating interaction regions (CIRs) during the last solar minimum from the period between 2007 and 2009. The numerical model simultaneously calculates the large-scale supersonic solar wind properties and its small-scale turbulent content from 0.3 au to the termination shock. Cosmic rays are then transported through the background, and thus computed, with diffusion coefficients derived from the solar wind turbulent properties, using a stochastic Parker approach. Ourmore » results demonstrate that GCR variations depend on the ratio of diffusion coefficients in the fast and slow solar winds. Stream interfaces inside the CIRs always lead to depressions of the GCR intensity. On the other hand, heliospheric current sheet (HCS) crossings do not appreciably affect GCR intensities in the model, which is consistent with the two observations under quiet solar wind conditions. Therefore, variations in diffusion coefficients associated with CIR stream interfaces are more important for GCR propagation than the drift effects of the HCS during a negative solar minimum.« less

Detecting cancer clusters in a regional population with local cluster tests and Bayesian smoothing methods: a simulation study

PubMed Central

2013-01-01

Background There is a rising public and political demand for prospective cancer cluster monitoring. But there is little empirical evidence on the performance of established cluster detection tests under conditions of small and heterogeneous sample sizes and varying spatial scales, such as are the case for most existing population-based cancer registries. Therefore this simulation study aims to evaluate different cluster detection methods, implemented in the open soure environment R, in their ability to identify clusters of lung cancer using real-life data from an epidemiological cancer registry in Germany. Methods Risk surfaces were constructed with two different spatial cluster types, representing a relative risk of RR = 2.0 or of RR = 4.0, in relation to the overall background incidence of lung cancer, separately for men and women. Lung cancer cases were sampled from this risk surface as geocodes using an inhomogeneous Poisson process. The realisations of the cancer cases were analysed within small spatial (census tracts, N = 1983) and within aggregated large spatial scales (communities, N = 78). Subsequently, they were submitted to the cluster detection methods. The test accuracy for cluster location was determined in terms of detection rates (DR), false-positive (FP) rates and positive predictive values. The Bayesian smoothing models were evaluated using ROC curves. Results With moderate risk increase (RR = 2.0), local cluster tests showed better DR (for both spatial aggregation scales > 0.90) and lower FP rates (both < 0.05) than the Bayesian smoothing methods. When the cluster RR was raised four-fold, the local cluster tests showed better DR with lower FPs only for the small spatial scale. At a large spatial scale, the Bayesian smoothing methods, especially those implementing a spatial neighbourhood, showed a substantially lower FP rate than the cluster tests. However, the risk increases at this scale were mostly diluted by data aggregation. Conclusion High resolution spatial scales seem more appropriate as data base for cancer cluster testing and monitoring than the commonly used aggregated scales. We suggest the development of a two-stage approach that combines methods with high detection rates as a first-line screening with methods of higher predictive ability at the second stage. PMID:24314148

SPIDER: Listening for the echoes of inflation from above the clouds

NASA Astrophysics Data System (ADS)

Filippini, Jeffrey; Spider Collaboration

2016-03-01

We report on the status of SPIDER, a balloon-borne instrument to map the polarization of the cosmic microwave background at large angular scales. SPIDER targets the B-mode signature of primordial gravitational waves, with a focus on mapping a large sky area at multiple frequencies. SPIDER's six monochromatic refracting telescopes (three each at 95 and 150 GHz) feed a total of more than 2000 antenna-coupled superconducting transition-edge sensors. A sapphire half-wave plate at the aperture of each telescope modulates sky polarization for control of systematics. We discuss SPIDER's first long-duration balloon flight in January 2015, as well as the status of data analysis and development toward a second flight.

Supercomputer optimizations for stochastic optimal control applications

NASA Technical Reports Server (NTRS)

Chung, Siu-Leung; Hanson, Floyd B.; Xu, Huihuang

1991-01-01

Supercomputer optimizations for a computational method of solving stochastic, multibody, dynamic programming problems are presented. The computational method is valid for a general class of optimal control problems that are nonlinear, multibody dynamical systems, perturbed by general Markov noise in continuous time, i.e., nonsmooth Gaussian as well as jump Poisson random white noise. Optimization techniques for vector multiprocessors or vectorizing supercomputers include advanced data structures, loop restructuring, loop collapsing, blocking, and compiler directives. These advanced computing techniques and superconducting hardware help alleviate Bellman's curse of dimensionality in dynamic programming computations, by permitting the solution of large multibody problems. Possible applications include lumped flight dynamics models for uncertain environments, such as large scale and background random aerospace fluctuations.

SEAPAK user's guide, version 2.0. Volume 1: System description

NASA Technical Reports Server (NTRS)

Mcclain, Charles R.; Darzi, Michael; Firestone, James K.; Fu, Gary; Yeh, Eueng-Nan; Endres, Daniel L.

1991-01-01

The SEAPAK is a user interactive satellite data analysis package that was developed for the processing and interpretation of Nimbus-7/Coastal Zone Color Scanner (CZCS) and the NOAA Advanced Very High Resolution Radiometer (AVHRR) data. Significant revisions were made to version 1.0 of the guide, and the ancillary environmental data analysis module was expanded. The package continues to emphasize user friendliness and user interactive data analyses. Additionally, because the scientific goals of the ocean color research being conducted have shifted to large space and time scales, batch processing capabilities for both satellite and ancillary environmental data analyses were enhanced, thus allowing large quantities of data to be ingested and analyzed in background.

Concurrent Spectral and Separation-space Views of Small-scale Anisotropy in Rotating Turbulence

NASA Astrophysics Data System (ADS)

Vallefuoco, D.; Godeferd, F. S.; Naso, A.

2017-12-01

Rotating turbulence is central in astrophysical, geophysical and industrial flows. A background rotation about a fixed axis introduces significant anisotropy in the turbulent dynamics through both linear and nonlinear mechanisms. The flow regime can be characterized by two independent non-dimensional parameters, e.g. the Reynolds and Rossby numbers or, equivalently, the ratio of the integral scale to the Kolmogorov scale L/η, and the ratio rZ/L, where rZ=√(ɛ/Ω3) is the Zeman scale, ɛ is the mean dissipation and Ω is the rotation rate. rZ is the scale at which the inertial timescale equals the rotation timescale. According to classical dimensional arguments (Zeman 1994), if the Reynolds number is large, scales much larger than rZ are mainly affected by rotation while scales much smaller than rZare dominated by the nonlinear dynamics and are expected to recover isotropy. In this work, we characterize incompressible rotating turbulence scale- and direction-dependent anisotropy through high Reynolds number pseudo-spectral forced DNS. We first focus on energy direction-dependent spectra in Fourier space: we show that a high anisotropy small wavenumber range and a low anisotropy large wavenumber range arise. Importantly, anisotropy arises even at scales much smaller than rZ and no small-scale isotropy is observed in our DNS, in contrast with previous numerical results (Delache et al. 2014, Mininni et al. 2012) but in agreement with experiments (Lamriben et al. 2011). Then, we estimate the value of the threshold wavenumber kT between these two anisotropic ranges for a large number of runs, and show that it corresponds to the scale at which dissipative effects are of the same order as those of rotation. Therefore, in the asymptotic inviscid limit, kT tends to infinity and only the low-wavenumber anisotropic range should persist. In this range anisotropy decreases with wavenumber, which is consistent with the classical Zeman argument. In addition, anisotropy at scales much smaller than rZ can be detected in physical space too, in particular for the third-order two-point vector moment F=<δu2 δu>, where δu is the velocity increment. We find the expected inertial trends for F (Galtier 2009) at scales sufficiently larger than the dissipative scale, while smaller scales exhibit qualitatively opposite anisotropic features.

Galaxy clusters and cold dark matter - A low-density unbiased universe?

NASA Technical Reports Server (NTRS)

Bahcall, Neta A.; Cen, Renyue

1992-01-01

Large-scale simulations of a universe dominated by cold dark matter (CDM) are tested against two fundamental properties of clusters of galaxies: the cluster mass function and the cluster correlation function. We find that standard biased CDM models are inconsistent with these observations for any bias parameter b. A low-density, low-bias CDM-type model, with or without a cosmological constant, appears to be consistent with both the cluster mass function and the cluster correlations. The low-density model agrees well with the observed correlation function of the Abell, Automatic Plate Measuring Facility (APM), and Edinburgh-Durham cluster catalogs. The model is in excellent agreement with the observed dependence of the correlation strength on cluster mean separation, reproducing the measured universal dimensionless cluster correlation. The low-density model is also consistent with other large-scale structure observations, including the APM angular galaxy-correlations, and for lambda = 1-Omega with the COBE results of the microwave background radiation fluctuations.

Cosmic Microwave Background Anisotropy Measurement from Python V

NASA Astrophysics Data System (ADS)

Coble, K.; Dodelson, S.; Dragovan, M.; Ganga, K.; Knox, L.; Kovac, J.; Ratra, B.; Souradeep, T.

2003-02-01

We analyze observations of the microwave sky made with the Python experiment in its fifth year of operation at the Amundsen-Scott South Pole Station in Antarctica. After modeling the noise and constructing a map, we extract the cosmic signal from the data. We simultaneously estimate the angular power spectrum in eight bands ranging from large (l~40) to small (l~260) angular scales, with power detected in the first six bands. There is a significant rise in the power spectrum from large to smaller (l~200) scales, consistent with that expected from acoustic oscillations in the early universe. We compare this Python V map to a map made from data taken in the third year of Python. Python III observations were made at a frequency of 90 GHz and covered a subset of the region of the sky covered by Python V observations, which were made at 40 GHz. Good agreement is obtained both visually (with a filtered version of the map) and via a likelihood ratio test.

Characterizing Atacama B-mode Search Detectors with a Half-Wave Plate

NASA Astrophysics Data System (ADS)

Simon, S. M.; Appel, J. W.; Campusano, L. E.; Choi, S. K.; Crowley, K. T.; Essinger-Hileman, T.; Gallardo, P.; Ho, S. P.; Kusaka, A.; Nati, F.; Palma, G. A.; Page, L. A.; Raghunathan, S.; Staggs, S. T.

2016-08-01

The Atacama B-Mode Search (ABS) instrument is a cryogenic (˜ 10 K) crossed-Dragone telescope located at an elevation of 5190 m in the Atacama Desert in Chile that observed for three seasons between February 2012 and October 2014. ABS observed the cosmic microwave background (CMB) at large angular scales (40<ℓ <500) to limit the B-mode polarization spectrum around the primordial B-mode peak from inflationary gravity waves at ℓ ˜ 100. The ABS focal plane consists of 480 transition-edge sensor (TES) bolometers. They are coupled to orthogonal polarizations from a planar ortho-mode transducer and observe at 145 GHz. ABS employs an ambient-temperature, rapidly rotating half-wave plate (HWP) to mitigate systematic effects and move the signal band away from atmospheric 1 / f noise, allowing for the recovery of large angular scales. We discuss how the signal at the second harmonic of the HWP rotation frequency can be used for data selection and for monitoring the detector responsivities.

Testing the robustness of Citizen Science projects: Evaluating the results of pilot project COMBER

PubMed Central

Faulwetter, Sarah; Dailianis, Thanos; Smith, Vincent Stuart; Koulouri, Panagiota; Dounas, Costas; Arvanitidis, Christos

2016-01-01

Abstract Background Citizen Science (CS) as a term implies a great deal of approaches and scopes involving many different fields of science. The number of the relevant projects globally has been increased significantly in the recent years. Large scale ecological questions can be answered only through extended observation networks and CS projects can support this effort. Although the need of such projects is apparent, an important part of scientific community cast doubt on the reliability of CS data sets. New information The pilot CS project COMBER has been created in order to provide evidence to answer the aforementioned question in the coastal marine biodiversity monitoring. The results of the current analysis show that a carefully designed CS project with clear hypotheses, wide participation and data sets validation, can be a valuable tool for the large scale and long term changes in marine biodiversity pattern change and therefore for relevant management and conservation issues. PMID:28174507

Asynchronous adaptive time step in quantitative cellular automata modeling

PubMed Central

Zhu, Hao; Pang, Peter YH; Sun, Yan; Dhar, Pawan

2004-01-01

Background The behaviors of cells in metazoans are context dependent, thus large-scale multi-cellular modeling is often necessary, for which cellular automata are natural candidates. Two related issues are involved in cellular automata based multi-cellular modeling: how to introduce differential equation based quantitative computing to precisely describe cellular activity, and upon it, how to solve the heavy time consumption issue in simulation. Results Based on a modified, language based cellular automata system we extended that allows ordinary differential equations in models, we introduce a method implementing asynchronous adaptive time step in simulation that can considerably improve efficiency yet without a significant sacrifice of accuracy. An average speedup rate of 4–5 is achieved in the given example. Conclusions Strategies for reducing time consumption in simulation are indispensable for large-scale, quantitative multi-cellular models, because even a small 100 × 100 × 100 tissue slab contains one million cells. Distributed and adaptive time step is a practical solution in cellular automata environment. PMID:15222901

Chameleon dark energy models with characteristic signatures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gannouji, Radouane; Department of Physics, Faculty of Science, Tokyo University of Science, 1-3, Kagurazaka, Shinjuku-ku, Tokyo 162-8601; Moraes, Bruno

2010-12-15

In chameleon dark energy models, local gravity constraints tend to rule out parameters in which observable cosmological signatures can be found. We study viable chameleon potentials consistent with a number of recent observational and experimental bounds. A novel chameleon field potential, motivated by f(R) gravity, is constructed where observable cosmological signatures are present both at the background evolution and in the growth rate of the perturbations. We study the evolution of matter density perturbations on low redshifts for this potential and show that the growth index today {gamma}{sub 0} can have significant dispersion on scales relevant for large scale structures.more » The values of {gamma}{sub 0} can be even smaller than 0.2 with large variations of {gamma} on very low redshifts for the model parameters constrained by local gravity tests. This gives a possibility to clearly distinguish these chameleon models from the {Lambda}-cold-dark-matter ({Lambda}CDM) model in future high-precision observations.« less

Testing Inflation with Large Scale Structure: Connecting Hopes with Reality

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alvarez, Marcello; Baldauf, T.; Bond, J. Richard

2014-12-15

The statistics of primordial curvature fluctuations are our window into the period of inflation, where these fluctuations were generated. To date, the cosmic microwave background has been the dominant source of information about these perturbations. Large-scale structure is, however, from where drastic improvements should originate. In this paper, we explain the theoretical motivations for pursuing such measurements and the challenges that lie ahead. In particular, we discuss and identify theoretical targets regarding the measurement of primordial non-Gaussianity. We argue that when quantified in terms of the local (equilateral) template amplitude fmore » $$loc\\atop{NL}$$ (f$$eq\\atop{NL}$$), natural target levels of sensitivity are Δf$$loc, eq\\atop{NL}$$ ≃ 1. We highlight that such levels are within reach of future surveys by measuring 2-, 3- and 4-point statistics of the galaxy spatial distribution. This paper summarizes a workshop held at CITA (University of Toronto) on October 23-24, 2014.« less

The Atacama B-Mode Search: CMB Polarimetry with Transition-Edge-Sensor Bolometers

NASA Astrophysics Data System (ADS)

Essinger-Hileman, T.; Appel, J. W.; Beal, J. A.; Cho, H. M.; Fowler, J.; Halpern, M.; Hasselfield, M.; Irwin, K. D.; Marriage, T. A.; Niemack, M. D.; Page, L.; Parker, L. P.; Pufu, S.; Staggs, S. T.; Stryzak, O.; Visnjic, C.; Yoon, K. W.; Zhao, Y.

2009-12-01

The Atacama B-mode Search (ABS) experiment is a 145 GHz polarimeter designed to measure the B-mode polarization of the Cosmic Microwave Background (CMB) at large angular scales. The ABS instrument will ship to the Atacama Desert of Chile fully tested and ready to observe in 2010. ABS will image large-angular-scale CMB polarization anisotropies onto a focal plane of 240 feedhorn-coupled, transition-edge sensor (TES) polarimeters, using a cryogenic crossed-Dragone design. The ABS detectors, which are fabricated at NIST, use orthomode transducers to couple orthogonal polarizations of incoming radiation onto separate TES bolometers. The incoming radiation is modulated by an ambient-temperature half-wave plate in front of the vacuum window at an aperture stop. Preliminary detector characterization indicates that the ABS detectors can achieve a sensitivity of 300 μK√s in the field. This paper describes the ABS optical design and detector readout scheme, including feedhorn design and performance, magnetic shielding, focal plane architecture, and cryogenic electronics.

Implementation of a flow-dependent background error correlation length scale formulation in the NEMOVAR OSTIA system

NASA Astrophysics Data System (ADS)

Fiedler, Emma; Mao, Chongyuan; Good, Simon; Waters, Jennifer; Martin, Matthew

2017-04-01

OSTIA is the Met Office's Operational Sea Surface Temperature (SST) and Ice Analysis system, which produces L4 (globally complete, gridded) analyses on a daily basis. Work is currently being undertaken to replace the original OI (Optimal Interpolation) data assimilation scheme with NEMOVAR, a 3D-Var data assimilation method developed for use with the NEMO ocean model. A dual background error correlation length scale formulation is used for SST in OSTIA, as implemented in NEMOVAR. Short and long length scales are combined according to the ratio of the decomposition of the background error variances into short and long spatial correlations. The pre-defined background error variances vary spatially and seasonally, but not on shorter time-scales. If the derived length scales applied to the daily analysis are too long, SST features may be smoothed out. Therefore a flow-dependent component to determining the effective length scale has also been developed. The total horizontal gradient of the background SST field is used to identify regions where the length scale should be shortened. These methods together have led to an improvement in the resolution of SST features compared to the previous OI analysis system, without the introduction of spurious noise. This presentation will show validation results for feature resolution in OSTIA using the OI scheme, the dual length scale NEMOVAR scheme, and the flow-dependent implementation.

Redshift-space equal-time angular-averaged consistency relations of the gravitational dynamics

NASA Astrophysics Data System (ADS)

Nishimichi, Takahiro; Valageas, Patrick

2015-12-01

We present the redshift-space generalization of the equal-time angular-averaged consistency relations between (ℓ+n )- and n -point polyspectra (i.e., the Fourier counterparts of correlation functions) of the cosmological matter density field. Focusing on the case of the ℓ=1 large-scale mode and n small-scale modes, we use an approximate symmetry of the gravitational dynamics to derive explicit expressions that hold beyond the perturbative regime, including both the large-scale Kaiser effect and the small-scale fingers-of-god effects. We explicitly check these relations, both perturbatively, for the lowest-order version that applies to the bispectrum, and nonperturbatively, for all orders but for the one-dimensional dynamics. Using a large ensemble of N -body simulations, we find that our relation on the bispectrum in the squeezed limit (i.e., the limit where one wave number is much smaller than the other two) is valid to better than 20% up to 1 h Mpc-1 , for both the monopole and quadrupole at z =0.35 , in a Λ CDM cosmology. Additional simulations done for the Einstein-de Sitter background suggest that these discrepancies mainly come from the breakdown of the approximate symmetry of the gravitational dynamics. For practical applications, we introduce a simple ansatz to estimate the new derivative terms in the relation using only observables. Although the relation holds worse after using this ansatz, we can still recover it within 20% up to 1 h Mpc-1 , at z =0.35 for the monopole. On larger scales, k =0.2 h Mpc-1 , it still holds within the statistical accuracy of idealized simulations of volume ˜8 h-3Gpc3 without shot-noise error.

Using radiocarbon to investigate soil respiration impacts on atmospheric CO2

NASA Astrophysics Data System (ADS)

Phillips, C. L.; LaFranchi, B. W.; McFarlane, K. J.; Desai, A. R.

2013-12-01

While soil respiration is believed to represent the largest single source of CO2 emissions on a global scale, there are few tools available to measure soil emissions at large spatial scales. We investigated whether radiocarbon (14C) abundance in CO2 could be used to detect and characterize soil emissions in the atmosphere, taking advantage of the fact that 14C abundance in soil carbon is elevated compared to the background atmosphere, a result of thermonuclear weapons testing during the mid-20th Century (i.e. bomb-C). Working in a temperate hardwood forest in Northern Wisconsin during 2011-12, we made semi-high-frequency measurements of CO2 at nested spatial scales from the soil subsurface to 150 m above ground level. These measurements were used to investigate seasonal patterns in respired C sources, and to evaluate whether variability in soil-respired Δ14C could also be detected in atmospheric measurements. In our ground-level measurements we found large seasonal variation in soil-respired 14CO2 that correlated with soil moisture, which was likely related to root activity. Atmospheric measurements of 14CO2 in the forest canopy (2 to 30m) were used to construct Keeling plots, and these provided larger spatial-scale estimates of respired 14CO2 that largely agreed with the soil-level measurements. In collaboration with the NOAA we also examined temporal patterns of 14CO2 at the Park Falls tall-tower (150m), and found elevated 14CO2 levels during summer months that likely resulted from increased respiration from heterotrophic sources. These results demonstrate that a fingerprint from soil-respired CO2 can be detected in the seasonal patterns of atmospheric 14CO2, even at a regionally-integrating spatial scale far from the soil surface.

Emission-angle and polarization-rotation effects in the lensed CMB

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lewis, Antony; Hall, Alex; Challinor, Anthony, E-mail: antony@cosmologist.info, E-mail: ahall@roe.ac.uk, E-mail: a.d.challinor@ast.cam.ac.uk

Lensing of the CMB is an important effect, and is usually modelled by remapping the unlensed CMB fields by a lensing deflection. However the lensing deflections also change the photon path so that the emission angle is no longer orthogonal to the background last-scattering surface. We give the first calculation of the emission-angle corrections to the standard lensing approximation from dipole (Doppler) sources for temperature and quadrupole sources for temperature and polarization. We show that while the corrections are negligible for the temperature and E-mode polarization, additional large-scale B-modes are produced with a white spectrum that dominates those from post-Bornmore » field rotation (curl lensing). On large scales about one percent of the total lensing-induced B-mode amplitude is expected to be due to this effect. However, the photon emission angle does remain orthogonal to the perturbed last-scattering surface due to time delay, and half of the large-scale emission-angle B modes cancel with B modes from time delay to give a total contribution of about half a percent. While not important for planned observations, the signal could ultimately limit the ability of delensing to reveal low amplitudes of primordial gravitational waves. We also derive the rotation of polarization due to multiple deflections between emission and observation. The rotation angle is of quadratic order in the deflection angle, and hence negligibly small: polarization typically rotates by less than an arcsecond, orders of magnitude less than a small-scale image rotates due to post-Born field rotation (which is quadratic in the shear). The field-rotation B modes dominate the other effects on small scales.« less

Baryons, universe and everything in between

NASA Astrophysics Data System (ADS)

Ho, Shirley

2008-06-01

This thesis is a tour of topics in cosmology, unified by their diversity and pursuits in better understanding of our Universe. The first chapter measures the Integrated Sachs-Wolfe effect as a function of redshift utilizing a large range of large scale structure observations and the cosmic microwave background. We combine the ISW likelihood function with weak lensing of CMB (which is described in Chapter 2) and CMB powerspectrum to constrain the equation of state of dark energy and the curvature of the Universe. The second chapter investigates the correlation of gravitational lensing of the cosmic microwave background (CMB) with several tracers of large-scale structure, and we find evidence for a positive cross-correlation at the 2.5s level. The third chapter explores the statistical properties of Luminous Red Galaxies in a sample of X-ray selected galaxy clusters, including the halo occupation distribution, how Poisson is the satellite distribution of LRGs and the radial profile of LRGs within clusters. The forth chapter explores the idea of using multiplicity of galaxies to understand their merging timescales. We find that (by using the multiplicity function of LRGs in Chapter 3) Massive halos (~ 10 14 M [Special characters omitted.] ) at low redshift have, for example, been bombarded by several ~ 10 13 M [Special characters omitted.] halos throughout their history and these accreted LRGs merge on relatively short timescales (~ 2 Gyr). The fifth chapter presents a new method for generating a template for the kinematic Sunyaev-Zel'dovich effect that can be used to detect the missing baryons. We assessed the feasibility of the method by investigating combinations of differeng galaxy surveys and CMB observations and find that we can detect the gas-momentum kSZ correlation, and thus the ionized gas, at significant signal-to-noise level.

Calculating the Sachs-Wolfe Effect from Solutions of Null Geodesics in Perturbed FRW Spacetime

NASA Astrophysics Data System (ADS)

Arroyo-Cárdenas, C. A.; Muñoz-Cuartas, J. C.

2017-07-01

In the upcoming precision era in cosmology, fine grained effects will be measured accurately. In particular, the late integrated Sachs-Wolfe (ISW) effect measurements will be improved to levels of unprecedented precision. The ISW consists on temperature fluctuations in the CMB due to gravitational redshift induced by the evolving potential well of large scale structure in the Universe. Currently there is large controversy related to the actual observability of the ISW effect. In principle, it is expected that, as an effect of the late accelerated expansion of the universe motivated by the current amount of dark energy, large scale structures may evolve rapidly, inducing an observable signature in the CMB photons in the way of a ISW anisotropy in the CMB. Tension arises since using galaxy redshift surveys some works report a temperature fluctuations with amplitude smaller than predicted by the Lambda-CDM. We argue that these discrepancies may be originated in the approximation that one has to make to get the classic Sachs-Wolfe effect. In this work, we compare the classic Sachs-Wolfe approximation with an exact solution to the propagation of photons in a dynamical background. We solve numerically the null geodesics on a perturbed FRW spacetime in the Newtonian gauge. From null geodesics, temperature fluctuations in the CMB due to the evolving potential has been calculated. Since solving geodesics accounts for more terms than solving the Sachs-Wolfe (approximated) integral, our results are more accurate. We have been able to substract the background cosmological redshift with the information provided by null geodesics, which allows to get an estimate of the integrated Sachs-Wolfe effect contribution to the temperature of the CMB.

Coronal Jets in Closed Magnetic Regions on the Sun

NASA Astrophysics Data System (ADS)

Wyper, Peter Fraser; DeVore, C. R.

2015-04-01

Coronal jets are dynamic, collimated structures observed in solar EUV and X-ray emission. They appear predominantly in the open field of coronal holes, but are also observed in areas of closed field, especially active regions. A common feature of coronal jets is that they originate from the field above a parasitic polarity of opposite sign to the surrounding field. Some process - such as instability onset or flux emergence - induces explosive reconnection between the closed “anemone” field and the surrounding open field that generates the jet. The lesser number of coronal jets in closed-field regions suggests a possible stabilizing effect of the closed configuration with respect to coronal jet formation. If the scale of the jet region is small compared with the background loop length, as in for example type II spicules, the nearby magnetic field may be treated as locally open. As such, one would expect that if a stabilizing effect exists it becomes most apparent as the scale of the anemone region approaches that of the background coronal loops.To investigate if coronal jets are indeed suppressed along shorter coronal loops, we performed a number of simulations of jets driven by a rotation of the parasitic polarity (as in the previous open-jet calculations by Pariat et. al 2009, 2010, 2015) embedded in a large-scale closed bipolar field. The simulations were performed with the state of the art Adaptively Refined Magnetohydrodynamics Solver. We will report here how the magnetic configuration above the anemone region determines the nature of the jet, when it is triggered, and how much of the stored magnetic energy is released. We show that regions in which the background field and the parasitic polarity region are of comparable scale naturally suppress explosive energy release. We will also show how in the post-jet relaxation phase a combination of confined MHD waves and weak current layers are generated by the jet along the background coronal loops, both of which may have implications for coronal heating.This work was supported by an appointment to the NASA Postdoctoral Program (P.F.W.) and by NASA’s Living With a Star Targeted Research and Technology program (C.R.D.).

Transport of cosmic-ray protons in intermittent heliospheric turbulence: Model and simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alouani-Bibi, Fathallah; Le Roux, Jakobus A., E-mail: fb0006@uah.edu

The transport of charged energetic particles in the presence of strong intermittent heliospheric turbulence is computationally analyzed based on known properties of the interplanetary magnetic field and solar wind plasma at 1 astronomical unit. The turbulence is assumed to be static, composite, and quasi-three-dimensional with a varying energy distribution between a one-dimensional Alfvénic (slab) and a structured two-dimensional component. The spatial fluctuations of the turbulent magnetic field are modeled either as homogeneous with a Gaussian probability distribution function (PDF), or as intermittent on large and small scales with a q-Gaussian PDF. Simulations showed that energetic particle diffusion coefficients both parallelmore » and perpendicular to the background magnetic field are significantly affected by intermittency in the turbulence. This effect is especially strong for parallel transport where for large-scale intermittency results show an extended phase of subdiffusive parallel transport during which cross-field transport diffusion dominates. The effects of intermittency are found to depend on particle rigidity and the fraction of slab energy in the turbulence, yielding a perpendicular to parallel mean free path ratio close to 1 for large-scale intermittency. Investigation of higher order transport moments (kurtosis) indicates that non-Gaussian statistical properties of the intermittent turbulent magnetic field are present in the parallel transport, especially for low rigidity particles at all times.« less

Inflation in the standard cosmological model

NASA Astrophysics Data System (ADS)

Uzan, Jean-Philippe

2015-12-01

The inflationary paradigm is now part of the standard cosmological model as a description of its primordial phase. While its original motivation was to solve the standard problems of the hot big bang model, it was soon understood that it offers a natural theory for the origin of the large-scale structure of the universe. Most models rely on a slow-rolling scalar field and enjoy very generic predictions. Besides, all the matter of the universe is produced by the decay of the inflaton field at the end of inflation during a phase of reheating. These predictions can be (and are) tested from their imprint of the large-scale structure and in particular the cosmic microwave background. Inflation stands as a window in physics where both general relativity and quantum field theory are at work and which can be observationally studied. It connects cosmology with high-energy physics. Today most models are constructed within extensions of the standard model, such as supersymmetry or string theory. Inflation also disrupts our vision of the universe, in particular with the ideas of chaotic inflation and eternal inflation that tend to promote the image of a very inhomogeneous universe with fractal structure on a large scale. This idea is also at the heart of further speculations, such as the multiverse. This introduction summarizes the connections between inflation and the hot big bang model and details the basics of its dynamics and predictions. xml:lang="fr"

The Cosmology Large Angular Scale Surveyor (CLASS)

NASA Astrophysics Data System (ADS)

Cleary, Joseph

2018-01-01

The Cosmology Large Angular Scale Surveyor (CLASS) is an array of four telescopes designed to measure the polarization of the Cosmic Microwave Background. CLASS aims to detect the B-mode polarization from primordial gravitational waves predicted by cosmic inflation theory, as well as the imprint left by reionization upon the CMB E-mode polarization. This will be achieved through a combination of observing strategy and state-of-the-art instrumentation. CLASS is observing 70% of the sky to characterize the CMB at large angular scales, which will measure the entire CMB power spectrum from the reionization peak to the recombination peak. The four telescopes operate at frequencies of 38, 93, 145, and 217 GHz, in order to estimate Galactic synchrotron and dust foregrounds while avoiding atmospheric absorption. CLASS employs rapid polarization modulation to overcome atmospheric and instrumental noise. Polarization sensitive cryogenic detectors with low noise levels provide CLASS the sensitivity required to constrain the tensor-to-scalar ratio down to levels of r ~ 0.01 while also measuring the optical depth the reionization to sample-variance levels. These improved constraints on the optical depth to reionization are required to pin down the mass of neutrinos from complementary cosmological data. CLASS has completed a year of observations at 38 GHz and is in the process of deploying the rest of the telescope array. This poster provides an overview and update on the CLASS science, hardware and survey operations.

Antimicrobial residues in animal waste and water resources proximal to large-scale swine and poultry feeding operations

USGS Publications Warehouse

Campagnolo, E.R.; Johnson, K.R.; Karpati, A.; Rubin, C.S.; Kolpin, D.W.; Meyer, M.T.; Esteban, J. Emilio; Currier, R.W.; Smith, K.; Thu, K.M.; McGeehin, M.

2002-01-01

Expansion and intensification of large-scale animal feeding operations (AFOs) in the United States has resulted in concern about environmental contamination and its potential public health impacts. The objective of this investigation was to obtain background data on a broad profile of antimicrobial residues in animal wastes and surface water and groundwater proximal to large-scale swine and poultry operations. The samples were measured for antimicrobial compounds using both radioimmunoassay and liquid chromatography/electrospray ionization-mass spectrometry (LC/ESI-MS) techniques. Multiple classes of antimicrobial compounds (commonly at concentrations of >100 μg/l) were detected in swine waste storage lagoons. In addition, multiple classes of antimicrobial compounds were detected in surface and groundwater samples collected proximal to the swine and poultry farms. This information indicates that animal waste used as fertilizer for crops may serve as a source of antimicrobial residues for the environment. Further research is required to determine if the levels of antimicrobials detected in this study are of consequence to human and/or environmental ecosystems. A comparison of the radioimmunoassay and LC/ESI-MS analytical methods documented that radioimmunoassay techniques were only appropriate for measuring residues in animal waste samples likely to contain high levels of antimicrobials. More sensitive LC/ESI-MS techniques are required in environmental samples, where low levels of antimicrobial residues are more likely.

Constraining models of f(R) gravity with Planck and WiggleZ power spectrum data

NASA Astrophysics Data System (ADS)

Dossett, Jason; Hu, Bin; Parkinson, David

2014-03-01

In order to explain cosmic acceleration without invoking ``dark'' physics, we consider f(R) modified gravity models, which replace the standard Einstein-Hilbert action in General Relativity with a higher derivative theory. We use data from the WiggleZ Dark Energy survey to probe the formation of structure on large scales which can place tight constraints on these models. We combine the large-scale structure data with measurements of the cosmic microwave background from the Planck surveyor. After parameterizing the modification of the action using the Compton wavelength parameter B0, we constrain this parameter using ISiTGR, assuming an initial non-informative log prior probability distribution of this cross-over scale. We find that the addition of the WiggleZ power spectrum provides the tightest constraints to date on B0 by an order of magnitude, giving log10(B0) < -4.07 at 95% confidence limit. Finally, we test whether the effect of adding the lensing amplitude ALens and the sum of the neutrino mass ∑mν is able to reconcile current tensions present in these parameters, but find f(R) gravity an inadequate explanation.

Primordial black holes from single field models of inflation

NASA Astrophysics Data System (ADS)

García-Bellido, Juan; Ruiz Morales, Ester

2017-12-01

Primordial black holes (PBH) have been shown to arise from high peaks in the matter power spectra of multi-field models of inflation. Here we show, with a simple toy model, that it is also possible to generate a peak in the curvature power spectrum of single-field inflation. We assume that the effective dynamics of the inflaton field presents a near-inflection point which slows down the field right before the end of inflation and gives rise to a prominent spike in the fluctuation power spectrum at scales much smaller than those probed by Cosmic Microwave Background (CMB) and Large Scale Structure (LSS) observations. This peak will give rise, upon reentry during the radiation era, to PBH via gravitational collapse. The mass and abundance of these PBH is such that they could constitute the totality of the Dark Matter today. We satisfy all CMB and LSS constraints and predict a very broad range of PBH masses. Some of these PBH are light enough that they will evaporate before structure formation, leaving behind a large curvature fluctuation on small scales. This broad mass distribution of PBH as Dark Matter will be tested in the future by AdvLIGO and LISA interferometers.

Large Scale Anthropogenic Reduction of Forest Cover in Last Glacial Maximum Europe

PubMed Central

Pfeiffer, Mirjam; Kolen, Jan C. A.; Davis, Basil A. S.

2016-01-01

Reconstructions of the vegetation of Europe during the Last Glacial Maximum (LGM) are an enigma. Pollen-based analyses have suggested that Europe was largely covered by steppe and tundra, and forests persisted only in small refugia. Climate-vegetation model simulations on the other hand have consistently suggested that broad areas of Europe would have been suitable for forest, even in the depths of the last glaciation. Here we reconcile models with data by demonstrating that the highly mobile groups of hunter-gatherers that inhabited Europe at the LGM could have substantially reduced forest cover through the ignition of wildfires. Similar to hunter-gatherers of the more recent past, Upper Paleolithic humans were masters of the use of fire, and preferred inhabiting semi-open landscapes to facilitate foraging, hunting and travel. Incorporating human agency into a dynamic vegetation-fire model and simulating forest cover shows that even small increases in wildfire frequency over natural background levels resulted in large changes in the forested area of Europe, in part because trees were already stressed by low atmospheric CO2 concentrations and the cold, dry, and highly variable climate. Our results suggest that the impact of humans on the glacial landscape of Europe may be one of the earliest large-scale anthropogenic modifications of the earth system. PMID:27902716

Potential impact of releases from a new Molybdenum-99 production facility on regional measurements of airborne xenon isotopes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bowyer, Ted W.; Eslinger, Paul W.; Cameron, Ian M.

2014-03-01

The monitoring of the radioactive xenon isotopes 131mXe, 133Xe, 133mXe, and 135Xe is important for the detection of nuclear explosions. While backgrounds of the xenon isotopes are short-lived, they are constantly replenished from activities dominated by the fission-based production of 99Mo used for medical procedures. One of the most critical locations on earth for the monitoring of nuclear explosions is the Korean peninsula, where the Democratic Republic of North Korea (DPRK) has announced that it had conducted three nuclear tests between 2009 and 2013. This paper explores the backgrounds that would be caused by the medium to large scale productionmore » of 99Mo in the region of the Korean peninsula.« less

Whistler mode refraction in highly nonuniform magnetic fields

NASA Astrophysics Data System (ADS)

Urrutia, J. M.; Stenzel, R.

2016-12-01

In a large laboratory plasma the propagation of whistler modes is measured in highly nonuniform magnetic fields created by a current-carrying wires. Ray tracing is not applicable since the wavelength and gradient scale length are comparable. The waves are excited with a loop antenna near the wire. The antenna launches an m=1 helicon mode in a uniform plasma. The total magnetic field consists of a weak uniform background field and a nearly circular field of a straight wire across the background field. A circular loop produces 3D null points and a 2D null line. The whistler wave propagation will be shown. It is relevant to whistler mode propagation in space plasmas near magnetic null-points, small flux ropes, lunar crustal magnetic fields and active wave injection experiments.

A post-reconstruction method to correct cupping artifacts in cone beam breast computed tomography

PubMed Central

Altunbas, M. C.; Shaw, C. C.; Chen, L.; Lai, C.; Liu, X.; Han, T.; Wang, T.

2007-01-01

In cone beam breast computed tomography (CT), scattered radiation leads to nonuniform biasing of CT numbers known as a cupping artifact. Besides being visual distractions, cupping artifacts appear as background nonuniformities, which impair efficient gray scale windowing and pose a problem in threshold based volume visualization/segmentation. To overcome this problem, we have developed a background nonuniformity correction method specifically designed for cone beam breast CT. With this technique, the cupping artifact is modeled as an additive background signal profile in the reconstructed breast images. Due to the largely circularly symmetric shape of a typical breast, the additive background signal profile was also assumed to be circularly symmetric. The radial variation of the background signals were estimated by measuring the spatial variation of adipose tissue signals in front view breast images. To extract adipose tissue signals in an automated manner, a signal sampling scheme in polar coordinates and a background trend fitting algorithm were implemented. The background fits compared with targeted adipose tissue signal value (constant throughout the breast volume) to get an additive correction value for each tissue voxel. To test the accuracy, we applied the technique to cone beam CT images of mastectomy specimens. After correction, the images demonstrated significantly improved signal uniformity in both front and side view slices. The reduction of both intra-slice and inter-slice variations in adipose tissue CT numbers supported our observations. PMID:17822018

Studying extragalactic background fluctuations with the Cosmic Infrared Background ExpeRiment 2 (CIBER-2)

NASA Astrophysics Data System (ADS)

Lanz, Alicia; Arai, Toshiaki; Battle, John; Bock, James; Cooray, Asantha; Hristov, Viktor; Korngut, Phillip; Lee, Dae Hee; Mason, Peter; Matsumoto, Toshio; Matsuura, Shuji; Morford, Tracy; Onishi, Yosuke; Shirahata, Mai; Tsumura, Kohji; Wada, Takehiko; Zemcov, Michael

2014-08-01

Fluctuations in the extragalactic background light trace emission from the history of galaxy formation, including the emission from the earliest sources from the epoch of reionization. A number of recent near-infrared measure- ments show excess spatial power at large angular scales inconsistent with models of z < 5 emission from galaxies. These measurements have been interpreted as arising from either redshifted stellar and quasar emission from the epoch of reionization, or the combined intra-halo light from stars thrown out of galaxies during merging activity at lower redshifts. Though astrophysically distinct, both interpretations arise from faint, low surface brightness source populations that are difficult to detect except by statistical approaches using careful observations with suitable instruments. The key to determining the source of these background anisotropies will be wide-field imaging measurements spanning multiple bands from the optical to the near-infrared. The Cosmic Infrared Background ExpeRiment 2 (CIBER-2) will measure spatial anisotropies in the extra- galactic infrared background caused by cosmological structure using six broad spectral bands. The experiment uses three 2048 x 2048 Hawaii-2RG near-infrared arrays in three cameras coupled to a single 28.5 cm telescope housed in a reusable sounding rocket-borne payload. A small portion of each array will also be combined with a linear-variable filter to make absolute measurements of the spectrum of the extragalactic background with high spatial resolution for deep subtraction of Galactic starlight. The large field of view and multiple spectral bands make CIBER-2 unique in its sensitivity to fluctuations predicted by models of lower limits on the luminosity of the first stars and galaxies and in its ability to distinguish between primordial and foreground anisotropies. In this paper the scientific motivation for CIBER-2 and details of its first flight instrumentation will be discussed, including detailed designs of the mechanical, cryogenic, and electrical systems. Plans for the future will also be presented.

Red, Straight, no bends: primordial power spectrum reconstruction from CMB and large-scale structure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ravenni, Andrea; Verde, Licia; Cuesta, Antonio J., E-mail: andrea.ravenni@pd.infn.it, E-mail: liciaverde@icc.ub.edu, E-mail: ajcuesta@icc.ub.edu

2016-08-01

We present a minimally parametric, model independent reconstruction of the shape of the primordial power spectrum. Our smoothing spline technique is well-suited to search for smooth features such as deviations from scale invariance, and deviations from a power law such as running of the spectral index or small-scale power suppression. We use a comprehensive set of the state-of the art cosmological data: Planck observations of the temperature and polarisation anisotropies of the cosmic microwave background, WiggleZ and Sloan Digital Sky Survey Data Release 7 galaxy power spectra and the Canada-France-Hawaii Lensing Survey correlation function. This reconstruction strongly supports the evidencemore » for a power law primordial power spectrum with a red tilt and disfavours deviations from a power law power spectrum including small-scale power suppression such as that induced by significantly massive neutrinos. This offers a powerful confirmation of the inflationary paradigm, justifying the adoption of the inflationary prior in cosmological analyses.« less

Red, Straight, no bends: primordial power spectrum reconstruction from CMB and large-scale structure

NASA Astrophysics Data System (ADS)

Ravenni, Andrea; Verde, Licia; Cuesta, Antonio J.

2016-08-01

We present a minimally parametric, model independent reconstruction of the shape of the primordial power spectrum. Our smoothing spline technique is well-suited to search for smooth features such as deviations from scale invariance, and deviations from a power law such as running of the spectral index or small-scale power suppression. We use a comprehensive set of the state-of the art cosmological data: Planck observations of the temperature and polarisation anisotropies of the cosmic microwave background, WiggleZ and Sloan Digital Sky Survey Data Release 7 galaxy power spectra and the Canada-France-Hawaii Lensing Survey correlation function. This reconstruction strongly supports the evidence for a power law primordial power spectrum with a red tilt and disfavours deviations from a power law power spectrum including small-scale power suppression such as that induced by significantly massive neutrinos. This offers a powerful confirmation of the inflationary paradigm, justifying the adoption of the inflationary prior in cosmological analyses.

“Estimating Regional Background Air Quality using Space/Time Ordinary Kriging to Support Exposure Studies”

EPA Science Inventory

Local-scale dispersion models are increasingly being used to perform exposure assessments. These types of models, while able to characterize local-scale air quality at increasing spatial scale, however, lack the ability to include background concentration in their overall estimat...

Pseudo-incompressible, finite-amplitude gravity waves: wave trains and stability

NASA Astrophysics Data System (ADS)

Schlutow, Mark; Klein, Rupert

2017-04-01

Based on weak asymptotic WKB-like solutions for two-dimensional atmospheric gravity waves (GWs) traveling wave solutions (wave trains) are derived and analyzed with respect to stability. A systematic multiple-scale analysis using the ratio of the dominant wavelength and the scale height as a scale separation parameter is applied on the fully compressible Euler equations. A distinguished limit favorable for GWs close to static instability, reveals that pseudo-incompressible rather than Boussinesq theory applies. A spectral expansion including a mean flow, combined with the additional WKB assumption of slowly varying phases and amplitudes, is used to find general weak asymptotic solutions. This ansatz allows for arbitrarily strong, non-uniform stratification and holds even for finite-amplitude waves. It is deduced that wave trains as leading order solutions can only exist if either some non-uniform background stratification is given but the wave train propagates only horizontally or if the wave train velocity vector is given but the background is isothermal. For the first case, general analytical solutions are obtained that may be used to model mountain lee waves. For the second case with the additional assumption of horizontal periodicity, upward propagating wave train fronts were found. These wave train fronts modify the mean flow beyond the non-acceleration theorem. Stability analysis reveal that they are intrinsically modulationally unstable. The range of validity for the scale separation parameter was tested with fully nonlinear simulations. Even for large values an excellent agreement with the theory was found.

The Mach number of the cosmic flow - A critical test for current theories

NASA Technical Reports Server (NTRS)

Ostriker, Jeremiah P.; Suto, Yusushi

1990-01-01

A new cosmological, self-contained test using the ratio of mean velocity and the velocity dispersion in the mean flow frame of a group of test objects is presented. To allow comparison with linear theory, the velocity field must first be smoothed on a suitable scale. In the context of linear perturbation theory, the Mach number M(R) which measures the ratio of power on scales larger than to scales smaller than the patch size R, is independent of the perturbation amplitude and also of bias. An apparent inconsistency is found for standard values of power-law index n = 1 and cosmological density parameter Omega = 1, when comparing values of M(R) predicted by popular models with tentative available observations. Nonstandard models based on adiabatic perturbations with either negative n or small Omega value also fail, due to creation of unacceptably large microwave background fluctuations.

A gyrofluid description of Alfvenic turbulence and its parallel electric field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bian, N. H.; Kontar, E. P.

2010-06-15

Anisotropic Alfvenic fluctuations with k{sub ||}/k{sub perpendicular}<<1 remain at frequencies much smaller than the ion cyclotron frequency in the presence of a strong background magnetic field. Based on the simplest truncation of the electromagnetic gyrofluid equations in a homogeneous plasma, a model for the energy cascade produced by Alfvenic turbulence is constructed, which smoothly connects the large magnetohydrodynamics scales and the small 'kinetic' scales. Scaling relations are obtained for the electromagnetic fluctuations, as a function of k{sub perpendicular} and k{sub ||}. Moreover, a particular attention is paid to the spectral structure of the parallel electric field which is produced bymore » Alfvenic turbulence. The reason is the potential implication of this parallel electric field in turbulent acceleration and transport of particles. For electromagnetic turbulence, this issue was raised some time ago in Hasegawa and Mima [J. Geophys. Res. 83, 1117 (1978)].« less

Workshop Report on Additive Manufacturing for Large-Scale Metal Components - Development and Deployment of Metal Big-Area-Additive-Manufacturing (Large-Scale Metals AM) System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Babu, Sudarsanam Suresh; Love, Lonnie J.; Peter, William H.

Additive manufacturing (AM) is considered an emerging technology that is expected to transform the way industry can make low-volume, high value complex structures. This disruptive technology promises to replace legacy manufacturing methods for the fabrication of existing components in addition to bringing new innovation for new components with increased functional and mechanical properties. This report outlines the outcome of a workshop on large-scale metal additive manufacturing held at Oak Ridge National Laboratory (ORNL) on March 11, 2016. The charter for the workshop was outlined by the Department of Energy (DOE) Advanced Manufacturing Office program manager. The status and impact ofmore » the Big Area Additive Manufacturing (BAAM) for polymer matrix composites was presented as the background motivation for the workshop. Following, the extension of underlying technology to low-cost metals was proposed with the following goals: (i) High deposition rates (approaching 100 lbs/h); (ii) Low cost (<$10/lbs) for steel, iron, aluminum, nickel, as well as, higher cost titanium, (iii) large components (major axis greater than 6 ft) and (iv) compliance of property requirements. The above concept was discussed in depth by representatives from different industrial sectors including welding, metal fabrication machinery, energy, construction, aerospace and heavy manufacturing. In addition, DOE’s newly launched High Performance Computing for Manufacturing (HPC4MFG) program was reviewed. This program will apply thermo-mechanical models to elucidate deeper understanding of the interactions between design, process, and materials during additive manufacturing. Following these presentations, all the attendees took part in a brainstorming session where everyone identified the top 10 challenges in large-scale metal AM from their own perspective. The feedback was analyzed and grouped in different categories including, (i) CAD to PART software, (ii) selection of energy source, (iii) systems development, (iv) material feedstock, (v) process planning, (vi) residual stress & distortion, (vii) post-processing, (viii) qualification of parts, (ix) supply chain and (x) business case. Furthermore, an open innovation network methodology was proposed to accelerate the development and deployment of new large-scale metal additive manufacturing technology with the goal of creating a new generation of high deposition rate equipment, affordable feed stocks, and large metallic components to enhance America’s economic competitiveness.« less

Large- and small-scale environmental factors drive distributions of cool-adapted plants in karstic microrefugia

PubMed Central

Vojtkó, András; Farkas, Tünde; Szabó, Anna; Havadtői, Krisztina; Vojtkó, Anna E.; Tölgyesi, Csaba; Cseh, Viktória; Erdős, László; Maák, István Elek; Keppel, Gunnar

2017-01-01

Background and aims Dolines are small- to large-sized bowl-shaped depressions of karst surfaces. They may constitute important microrefugia, as thermal inversion often maintains cooler conditions within them. This study aimed to identify the effects of large- (macroclimate) and small-scale (slope aspect and vegetation type) environmental factors on cool-adapted plants in karst dolines of East-Central Europe. We also evaluated the potential of these dolines to be microrefugia that mitigate the effects of climate change on cool-adapted plants in both forest and grassland ecosystems. Methods We compared surveys of plant species composition that were made between 2007 and 2015 in 21 dolines distributed across four mountain ranges (sites) in Hungary and Romania. We examined the effects of environmental factors on the distribution and number of cool-adapted plants on three scales: (1) regional (all sites); (2) within sites and; (3) within dolines. Generalized linear models and non-parametric tests were used for the analyses. Key Results Macroclimate, vegetation type and aspect were all significant predictors of the diversity of cool-adapted plants. More cool-adapted plants were recorded in the coolest site, with only few found in the warmest site. At the warmest site, the distribution of cool-adapted plants was restricted to the deepest parts of dolines. Within sites of intermediate temperature and humidity, the effect of vegetation type and aspect on the diversity of cool-adapted plants was often significant, with more taxa being found in grasslands (versus forests) and on north-facing slopes (versus south-facing slopes). Conclusions There is large variation in the number and spatial distribution of cool-adapted plants in karst dolines, which is related to large- and small-scale environmental factors. Both macro- and microrefugia are therefore likely to play important roles in facilitating the persistence of cool-adapted plants under global warming. PMID:28025290

A cooperative strategy for parameter estimation in large scale systems biology models

PubMed Central

2012-01-01

Background Mathematical models play a key role in systems biology: they summarize the currently available knowledge in a way that allows to make experimentally verifiable predictions. Model calibration consists of finding the parameters that give the best fit to a set of experimental data, which entails minimizing a cost function that measures the goodness of this fit. Most mathematical models in systems biology present three characteristics which make this problem very difficult to solve: they are highly non-linear, they have a large number of parameters to be estimated, and the information content of the available experimental data is frequently scarce. Hence, there is a need for global optimization methods capable of solving this problem efficiently. Results A new approach for parameter estimation of large scale models, called Cooperative Enhanced Scatter Search (CeSS), is presented. Its key feature is the cooperation between different programs (“threads”) that run in parallel in different processors. Each thread implements a state of the art metaheuristic, the enhanced Scatter Search algorithm (eSS). Cooperation, meaning information sharing between threads, modifies the systemic properties of the algorithm and allows to speed up performance. Two parameter estimation problems involving models related with the central carbon metabolism of E. coli which include different regulatory levels (metabolic and transcriptional) are used as case studies. The performance and capabilities of the method are also evaluated using benchmark problems of large-scale global optimization, with excellent results. Conclusions The cooperative CeSS strategy is a general purpose technique that can be applied to any model calibration problem. Its capability has been demonstrated by calibrating two large-scale models of different characteristics, improving the performance of previously existing methods in both cases. The cooperative metaheuristic presented here can be easily extended to incorporate other global and local search solvers and specific structural information for particular classes of problems. PMID:22727112

Properties and spatial distribution of galaxy superclusters

NASA Astrophysics Data System (ADS)

Liivamägi, Lauri Juhan

2017-01-01

Astronomy is a science that can offer plenty of unforgettable imagery, and the large-scale distribution of galaxies is no exception. Among the first features the viewer's eye is likely to be drawn to, are large concentrations of galaxies - galaxy superclusters, contrasting to the seemingly empty regions beside them. Superclusters can extend from tens to over hundred megaparsecs, they contain from hundreds to thousands of galaxies, and many galaxy groups and clusters. Unlike galaxy clusters, superclusters are clearly unrelaxed systems, not gravitationally bound as crossing times exceed the age of the universe, and show little to no radial symmetry. Superclusters, as part of the large-scale structure, are sensitive to the initial power spectrum and the following evolution. They are massive enough to leave an imprint on the cosmic microwave background radiation. Superclusters can also provide an unique environment for their constituent galaxies and galaxy clusters. In this study we used two different observational and one simulated galaxy samples to create several catalogues of structures that, we think, correspond to what are generally considered galaxy superclusters. Superclusters were delineated as continuous over-dense regions in galaxy luminosity density fields. When calculating density fields several corrections were applied to remove small-scale redshift distortions and distance-dependent selection effects. Resulting catalogues of objects display robust statistical properties, showing that flux-limited galaxy samples can be used to create nearly volume-limited catalogues of superstructures. Generally, large superclusters can be regarded as massive, often branching filamentary structures, that are mainly characterised by their length. Smaller superclusters, on the other hand, can display a variety of shapes. Spatial distribution of superclusters shows large-scale variations, with high-density concentrations often found in semi-regularly spaced groups. Future studies are needed to quantify the relations between superclusters and finer details of the galaxy distribution. Supercluster catalogues from this thesis have already been used in numerous other studies.

Poisson denoising on the sphere: application to the Fermi gamma ray space telescope

NASA Astrophysics Data System (ADS)

Schmitt, J.; Starck, J. L.; Casandjian, J. M.; Fadili, J.; Grenier, I.

2010-07-01

The Large Area Telescope (LAT), the main instrument of the Fermi gamma-ray Space telescope, detects high energy gamma rays with energies from 20 MeV to more than 300 GeV. The two main scientific objectives, the study of the Milky Way diffuse background and the detection of point sources, are complicated by the lack of photons. That is why we need a powerful Poisson noise removal method on the sphere which is efficient on low count Poisson data. This paper presents a new multiscale decomposition on the sphere for data with Poisson noise, called multi-scale variance stabilizing transform on the sphere (MS-VSTS). This method is based on a variance stabilizing transform (VST), a transform which aims to stabilize a Poisson data set such that each stabilized sample has a quasi constant variance. In addition, for the VST used in the method, the transformed data are asymptotically Gaussian. MS-VSTS consists of decomposing the data into a sparse multi-scale dictionary like wavelets or curvelets, and then applying a VST on the coefficients in order to get almost Gaussian stabilized coefficients. In this work, we use the isotropic undecimated wavelet transform (IUWT) and the curvelet transform as spherical multi-scale transforms. Then, binary hypothesis testing is carried out to detect significant coefficients, and the denoised image is reconstructed with an iterative algorithm based on hybrid steepest descent (HSD). To detect point sources, we have to extract the Galactic diffuse background: an extension of the method to background separation is then proposed. In contrary, to study the Milky Way diffuse background, we remove point sources with a binary mask. The gaps have to be interpolated: an extension to inpainting is then proposed. The method, applied on simulated Fermi LAT data, proves to be adaptive, fast and easy to implement.

Characterizing the Cosmic Infrared Background Fluctuations

NASA Astrophysics Data System (ADS)

Li, Yanxia

2015-08-01

A salient feature of the Cosmic Infrared Background (CIB) fluctuations is that their spatial power spectrum rises a factor of ~10 above the expected contribution from all known sources at angular scales >20‧‧. A tantalizing large-scale correlation signal between the residual Cosmic X-ray Background (CXB) and CIB found in the Extended Groth Strip (EGS) further suggests that at least 20% of the CIB fluctuations are associated with accreting X-ray sources, with efficient energy production similar to black holes. However, there is still a controversy about the sources that produce the excess flux. They could be faint, local populations with different spatial distribution from other known galaxies, e.g., intra-halo light (emitted from stars in the outskirts of local galaxies), or really high-z populations at the epoch of reionization that we know little of. Constraining the origin of the CIB fluctuations will help to establish our understanding of the overall cosmic energy budget.In this talk, we will present our plan to break down this controversy, current state of data collection and analysis.(1) We will combine the archival Spitzer/IRAC and Herschel/PACS data, with the Chandra data of the Cosmic Evolution Survey (COSMOS), to accurately measure the source-subtracted CIB and CXB fluctuations to the largest angular scale (~1-2 deg) to date. The newly discovered link between CIB and CXB fluctuations found in the EGS will be revisited in the COSMOS, which provides better photon statistics. (2) We have been working on cross-correlating the unresolved background with the discrete sources detected at shorter wavelengths (1- 2μm), using ground-based multi-wavelength observations. In addition to exploring the Pan-STARRS 3PI and Medium Deep Survey database, we have also been awarded the telescope time of CFHT/WIRCam and Subaru/Hyper-Suprime-Cam for this purpose. The preliminary data analysis will be presented.

Reverse-Time Imaging Based on Full-Waveform Inverted Velocity Model for Nondestructive Testing of Heterogeneous Engineered Structures

NASA Astrophysics Data System (ADS)

Nguyen, L. T.; Modrak, R. T.; Saenger, E. H.; Tromp, J.

2017-12-01

Reverse-time migration (RTM) can reconstruct reflectors and scatterers by cross-correlating the source wavefield and the receiver wavefield given a known velocity model of the background. In nondestructive testing, however, the engineered structure under inspection is often composed of layers of various materials and the background material has been degraded non-uniformly because of environmental or operational effects. On the other hand, ultrasonic waveform tomography based on the principles of full-waveform inversion (FWI) has succeeded in detecting anomalous features in engineered structures. But the building of the wave velocity model of the comprehensive small-size and high-contrast defect(s) is difficult because it requires computationally expensive high-frequency numerical wave simulations and an accurate understanding of large-scale background variations of the engineered structure.To reduce computational cost and improve detection of small defects, a useful approach is to divide the waveform tomography procedure into two steps: first, a low-frequency model-building step aimed at recovering background structure using FWI, and second, a high-frequency imaging step targeting defects using RTM. Through synthetic test cases, we show that the two-step procedure appears more promising in most cases than a single-step inversion. In particular, we find that the new workflow succeeds in the challenging scenario where the defect lies along preexisting layer interface in a composite bridge deck and in related experiments involving noisy data or inaccurate source parameters. The results reveal the potential of the new wavefield imaging method and encourage further developments in data processing, enhancing computation power, and optimizing the imaging workflow itself so that the procedure can efficiently be applied to geometrically complex 3D solids and waveguides. Lastly, owing to the scale invariance of the elastic wave equation, this imaging procedure can be transferred to applications in regional scales as well.

Fourier-space combination of Planck and Herschel images

NASA Astrophysics Data System (ADS)

Abreu-Vicente, J.; Stutz, A.; Henning, Th.; Keto, E.; Ballesteros-Paredes, J.; Robitaille, T.

2017-08-01

Context. Herschel has revolutionized our ability to measure column densities (NH) and temperatures (T) of molecular clouds thanks to its far infrared multiwavelength coverage. However, the lack of a well defined background intensity level in the Herschel data limits the accuracy of the NH and T maps. Aims: We aim to provide a method that corrects the missing Herschel background intensity levels using the Planck model for foreground Galactic thermal dust emission. For the Herschel/PACS data, both the constant-offset as well as the spatial dependence of the missing background must be addressed. For the Herschel/SPIRE data, the constant-offset correction has already been applied to the archival data so we are primarily concerned with the spatial dependence, which is most important at 250 μm. Methods: We present a Fourier method that combines the publicly available Planck model on large angular scales with the Herschel images on smaller angular scales. Results: We have applied our method to two regions spanning a range of Galactic environments: Perseus and the Galactic plane region around l = 11deg (HiGal-11). We post-processed the combined dust continuum emission images to generate column density and temperature maps. We compared these to previously adopted constant-offset corrections. We find significant differences (≳20%) over significant ( 15%) areas of the maps, at low column densities (NH ≲ 1022 cm-2) and relatively high temperatures (T ≳ 20 K). We have also applied our method to synthetic observations of a simulated molecular cloud to validate our method. Conclusions: Our method successfully corrects the Herschel images, including both the constant-offset intensity level and the scale-dependent background variations measured by Planck. Our method improves the previous constant-offset corrections, which did not account for variations in the background emission levels. The image FITS files used in this paper are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/604/A65

Baryonic matter perturbations in decaying vacuum cosmology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marttens, R.F. vom; Zimdahl, W.; Hipólito-Ricaldi, W.S., E-mail: rodrigovonmarttens@gmail.com, E-mail: wiliam.ricaldi@ufes.br, E-mail: winfried.zimdahl@pq.cnpq.br

2014-08-01

We consider the perturbation dynamics for the cosmic baryon fluid and determine the corresponding power spectrum for a Λ(t)CDM model in which a cosmological term decays into dark matter linearly with the Hubble rate. The model is tested by a joint analysis of data from supernovae of type Ia (SNIa) (Constitution and Union 2.1), baryonic acoustic oscillations (BAO), the position of the first peak of the anisotropy spectrum of the cosmic microwave background (CMB) and large-scale-structure (LSS) data (SDSS DR7). While the homogeneous and isotropic background dynamics is only marginally influenced by the baryons, there are modifications on the perturbativemore » level if a separately conserved baryon fluid is included. Considering the present baryon fraction as a free parameter, we reproduce the observed abundance of the order of 5% independently of the dark-matter abundance which is of the order of 32% for this model. Generally, the concordance between background and perturbation dynamics is improved if baryons are explicitly taken into account.« less

Measurements of the cosmic background radiation

NASA Technical Reports Server (NTRS)

Lubin, P.; Villela, T.

1987-01-01

Maps of the large scale structure (theta is greater than 6 deg) of the cosmic background radiation covering 90 percent of the sky are now available. The data show a very strong 50-100 sigma (statistical error) dipole component, interpreted as being due to our motion, with a direction of alpha = 11.5 + or - 0.15 hours, sigma = -5.6 + or - 2.0 deg. The inferred direction of the velocity of our galaxy relative to the cosmic background radiation is alpha = 10.6 + or - 0.3 hours, sigma = -2.3 + or - 5 deg. This is 44 deg from the center of the Virgo cluster. After removing the dipole component, the data show a galactic signature but no apparent residual structure. An autocorrelation of the residual data, after substraction of the galactic component from a combined Berkeley (3 mm) and Princeton (12 mm) data sets, show no apparent structure from 10 to 180 deg with a rms of 0.01 mK(sup 2). At 90 percent confidence level limit of .00007 is placed on a quadrupole component.

New window into stochastic gravitational wave background.

PubMed

Rotti, Aditya; Souradeep, Tarun

2012-11-30

A stochastic gravitational wave background (SGWB) would gravitationally lens the cosmic microwave background (CMB) photons. We correct the results provided in existing literature for modifications to the CMB polarization power spectra due to lensing by gravitational waves. Weak lensing by gravitational waves distorts all four CMB power spectra; however, its effect is most striking in the mixing of power between the E mode and B mode of CMB polarization. This suggests the possibility of using measurements of the CMB angular power spectra to constrain the energy density (Ω(GW)) of the SGWB. Using current data sets (QUAD, WMAP, and ACT), we find that the most stringent constraints on the present Ω(GW) come from measurements of the angular power spectra of CMB temperature anisotropies. In the near future, more stringent bounds on Ω(GW) can be expected with improved upper limits on the B modes of CMB polarization. Any detection of B modes of CMB polarization above the expected signal from large scale structure lensing could be a signal for a SGWB.

Lenses in the forest: cross correlation of the Lyman-alpha flux with cosmic microwave background lensing.

PubMed

Vallinotto, Alberto; Das, Sudeep; Spergel, David N; Viel, Matteo

2009-08-28

We present a theoretical estimate for a new observable: the cross correlation between the Lyman-alpha flux fluctuations in quasar spectra and the convergence of the cosmic microwave background as measured along the same line of sight. As a first step toward the assessment of its detectability, we estimate the signal-to-noise ratio using linear theory. Although the signal-to-noise is small for a single line of sight and peaks at somewhat smaller redshifts than those probed by the Lyman-alpha forest, we estimate a total signal-to-noise of 9 for cross correlating quasar spectra of SDSS-III with Planck and 20 for cross correlating with a future polarization based cosmic microwave background experiment. The detection of this effect would be a direct measure of the neutral hydrogen-matter cross correlation and could provide important information on the growth of structures at large scales in a redshift range which is still poorly probed.

A two-fluid approximation for calculating the cosmic microwave background anisotropies

NASA Technical Reports Server (NTRS)

Seljak, Uros

1994-01-01

We present a simplified treatment for calculating the cosmic microwave background anisotropy power spectrum in adiabatic models. It consists of solving for the evolution of a two-fluid model until the epoch of recombination and then integrating over the sources to obtain the cosmic microwave background (CMB) anisotropy power spectrum. The approximation is useful both for a physical understanding of CMB anisotropies as well as for a quantitative analysis of cosmological models. Comparison with exact calculations shows that the accuracy is typically 10%-20% over a large range of angles and cosmological models, including those with curvature and cosmological constant. Using this approximation we investigate the dependence of the CMB anisotropy on the cosmological parameters. We identify six dimensionless parameters that uniquely determine the anisotropy power spectrum within our approximation. CMB experiments on different angular scales could in principle provide information on all these parameters. In particular, mapping of the Doppler peaks would allow an independent determination of baryon mass density, matter mass density, and the Hubble constant.

Detection of Chorus Elements and other Wave Signatures Using Geometric Computational Techniques in the Van Allen radiation belts

NASA Astrophysics Data System (ADS)

Sengupta, A.; Kletzing, C.; Howk, R.; Kurth, W. S.

2017-12-01

An important goal of the Van Allen Probes mission is to understand wave particle interactions that can energize relativistic electron in the Earth's Van Allen radiation belts. The EMFISIS instrumentation suite provides measurements of wave electric and magnetic fields of wave features such as chorus that participate in these interactions. Geometric signal processing discovers structural relationships, e.g. connectivity across ridge-like features in chorus elements to reveal properties such as dominant angles of the element (frequency sweep rate) and integrated power along the a given chorus element. These techniques disambiguate these wave features against background hiss-like chorus. This enables autonomous discovery of chorus elements across the large volumes of EMFISIS data. At the scale of individual or overlapping chorus elements, topological pattern recognition techniques enable interpretation of chorus microstructure by discovering connectivity and other geometric features within the wave signature of a single chorus element or between overlapping chorus elements. Thus chorus wave features can be quantified and studied at multiple scales of spectral geometry using geometric signal processing techniques. We present recently developed computational techniques that exploit spectral geometry of chorus elements and whistlers to enable large-scale automated discovery, detection and statistical analysis of these events over EMFISIS data. Specifically, we present different case studies across a diverse portfolio of chorus elements and discuss the performance of our algorithms regarding precision of detection as well as interpretation of chorus microstructure. We also provide large-scale statistical analysis on the distribution of dominant sweep rates and other properties of the detected chorus elements.

The Majorana Demonstrator: A search for neutrinoless double-beta decay of germanium-76

NASA Astrophysics Data System (ADS)

Elliott, S. R.; Abgrall, N.; Aguayo, E.; Avignone, F. T., III; Barabash, A. S.; Bertrand, F. E.; Boswell, M.; Brudanin, V.; Busch, M.; Caldwell, A. S.; Chan, Y.-D.; Christofferson, C. D.; Combs, D. C.; Detwiler, J. A.; Doe, P. J.; Efremenko, Yu.; Egorov, V.; Ejiri, H.; Esterline, J.; Fast, J. E.; Finnerty, P.; Fraenkle, F. M.; Galindo-Uribarri, A.; Giovanetti, G. K.; Goett, J.; Green, M. P.; Gruszko, J.; Guiseppe, V. E.; Gusev, K.; Hallin, A. L.; Hazama, R.; Hegai, A.; Henning, R.; Hoppe, E. W.; Howard, S.; Howe, M. A.; Keeter, K. J.; Kidd, M. F.; Kochetov, O.; Konovalov, S. I.; Kouzes, R. T.; LaFerriere, B. D.; Leon, J.; Leviner, L. E.; Loach, J. C.; MacMullin, S.; Martin, R. D.; Mertens, S.; Mizouni, L.; Nomachi, M.; Orrell, J. L.; O'Shaughnessy, C.; Overman, N. R.; Phillips, D. G., II; Poon, A. W. P.; Pushkin, K.; Radford, D. C.; Rielage, K.; Robertson, R. G. H.; Ronquest, M. C.; Schubert, A. G.; Shanks, B.; Shima, T.; Shirchenko, M.; Snavely, K. J.; Snyder, N.; Soin, A.; Strain, J.; Suriano, A. M.; Timkin, V.; Tornow, W.; Varner, R. L.; Vasilyev, S.; Vetter, K.; Vorren, K.; White, B. R.; Wilkerson, J. F.; Xu, W.; Yakushev, E.; Young, A. R.; Yu, C.-H.; Yumatov, V.

2013-12-01

The Majorana collaboration is searching for neutrinoless double beta decay using 76Ge, which has been shown to have a number of advantages in terms of sensitivities and backgrounds. The observation of neutrinoless double-beta decay would show that lepton number is violated and that neutrinos are Majorana particles and would simultaneously provide information on neutrino mass. Attaining sensitivities for neutrino masses in the inverted hierarchy region, 15 - 50 meV, will require large, tonne-scale detectors with extremely low backgrounds, at the level of ˜1 count/t-y or lower in the region of the signal. The Majorana collaboration, with funding support from DOE Office of Nuclear Physics and NSF Particle Astrophysics, is constructing the Demonstrator, an array consisting of 40 kg of p-type point-contact high-purity germanium (HPGe) detectors, of which ˜30 kg will be enriched to 87% in 76Ge. The Demonstrator is being constructed in a clean room laboratory facility at the 4850' level (4300 m.w.e.) of the Sanford Underground Research Facility (SURF) in Lead, SD. It utilizes a compact graded shield approach with the inner portion consisting of ultra-clean Cu that is being electroformed and machined underground. The primary aim of the Demonstrator is to show the feasibility of a future tonne-scale measurement in terms of backgrounds and scalability.

[Cosmic Microwave Background (CMB) Anisotropies

NASA Technical Reports Server (NTRS)

Silk, Joseph

1998-01-01

One of the main areas of research is the theory of cosmic microwave background (CMB) anisotropies and analysis of CMB data. Using the four year COBE data we were able to improve existing constraints on global shear and vorticity. We found that, in the flat case (which allows for greatest anisotropy), (omega/H)0 less than 10(exp -7), where omega is the vorticity and H is the Hubble constant. This is two orders of magnitude lower than the tightest, previous constraint. We have defined a new set of statistics which quantify the amount of non-Gaussianity in small field cosmic microwave background maps. By looking at the distribution of power around rings in Fourier space, and at the correlations between adjacent rings, one can identify non-Gaussian features which are masked by large scale Gaussian fluctuations. This may be particularly useful for identifying unresolved localized sources and line-like discontinuities. Levin and collaborators devised a method to determine the global geometry of the universe through observations of patterns in the hot and cold spots of the CMB. We have derived properties of the peaks (maxima) of the CMB anisotropies expected in flat and open CDM models. We represent results for angular resolutions ranging from 5 arcmin to 20 arcmin (antenna FWHM), scales that are relevant for the MAP and COBRA/SAMBA space missions and the ground-based interferometer. Results related to galaxy formation and evolution are also discussed.

The Productive Ward Program™: A Two-Year Implementation Impact Review Using a Longitudinal Multilevel Study.

PubMed

Van Bogaert, Peter; Van Heusden, Danny; Verspuy, Martijn; Wouters, Kristien; Slootmans, Stijn; Van der Straeten, Johnny; Van Aken, Paul; White, Mark

2017-03-01

Aim To investigate the impact of the quality improvement program "Productive Ward - Releasing Time to Care™" using nurses' and midwives' reports of practice environment, burnout, quality of care, job outcomes, as well as workload, decision latitude, social capital, and engagement. Background Despite the requirement for health systems to improve quality and the proliferation of quality improvement programs designed for healthcare, the empirical evidence supporting large-scale quality improvement programs impacting patient satisfaction, staff engagement, and quality care remains sparse. Method A longitudinal study was performed in a large 600-bed acute care university hospital at two measurement intervals for nurse practice environment, burnout, and quality of care and job outcomes and three measurement intervals for workload, decision latitude, social capital, and engagement between June 2011 and November 2014. Results Positive results were identified in practice environment, decision latitude, and social capital. Less favorable results were identified in relation to perceived workload, emotional exhaustion. and vigor. Moreover, measures of quality of care and job satisfaction were reported less favorably. Conclusion This study highlights the need to further understand how to implement large-scale quality improvement programs so that they integrate with daily practices and promote "quality improvement" as "business as usual."

Control-Structure-Interaction (CSI) technologies and trends to future NASA missions

NASA Technical Reports Server (NTRS)

1990-01-01

Control-structure-interaction (CSI) issues which are relevant for future NASA missions are reviewed. This goal was achieved by: (1) reviewing large space structures (LSS) technologies to provide a background and survey of the current state of the art (SOA); (2) analytically studying a focus mission to identify opportunities where CSI technology may be applied to enhance or enable future NASA spacecraft; and (3) expanding a portion of the focus mission, the large antenna, to provide in-depth trade studies, scaling laws, and methodologies which may be applied to other NASA missions. Several sections are presented. Section 1 defines CSI issues and presents an overview of the relevant modeling and control issues for LLS. Section 2 presents the results of the three phases of the CSI study. Section 2.1 gives the results of a CSI study conducted with the Geostationary Platform (Geoplat) as the focus mission. Section 2.2 contains an overview of the CSI control design methodology available in the technical community. Included is a survey of the CSI ground-based experiments which were conducted to verify theoretical performance predictions. Section 2.3 presents and demonstrates a new CSI scaling law methodology for assessing potential CSI with large antenna systems.

Characteristics of ripple structures revealed in OH airglow images

NASA Astrophysics Data System (ADS)

Li, Jing; Li, Tao; Dou, Xiankang; Fang, Xin; Cao, Bing; She, Chiao-Yao; Nakamura, Takuji; Manson, Alan; Meek, Chris; Thorsen, Denise

2017-03-01

Small-scale ripple structures observed in OH airglow images are most likely induced by either dynamic instability due to large wind shear or convective instability due to superadiabatic lapse rate. Using the data set taken in the mesopause region with an OH all-sky imager at Yucca Ridge Field Station, Colorado (40.7°N, 104.9°W), from September 2003 to December 2005, we study the characteristics and seasonal variations of ripple structures. By analyzing the simultaneous background wind and temperature observed by the nearby sodium temperature/wind lidar at Fort Collins, Colorado (40.6°N, 105°W), and a nearby medium-frequency radar at Platteville, Colorado (40.2°N, 105.8°W), we are able to statistically study the possible relation between ripples and the background atmosphere conditions. Characteristics and seasonal variations of ripples are presented in detail in this study. The occurrence frequency of ripples exhibits clear seasonal variability, with peak in autumn. The occurrence of ripples shows a local time dependence, which is most likely associated with the solar tides. The lifetime and spatial scale of these ripples are typically 5-20 min and 5-10 km, respectively, and most of the ripples move preferentially either southward or northward. However, more than half of the observed ripples do not advect with background flow; they have higher Richardson numbers than those ripples that advect with background flow. It is possible that they are not instability features but wave structures that are hard to be distinguished from the real instability features.

Application of RNAMlet to surface defect identification of steels

NASA Astrophysics Data System (ADS)

Xu, Ke; Xu, Yang; Zhou, Peng; Wang, Lei

2018-06-01

As three main production lines of steels, continuous casting slabs, hot rolled steel plates and cold rolled steel strips have different surface appearances and are produced at different speeds of their production lines. Therefore, the algorithms for the surface defect identifications of the three steel products have different requirements for real-time and anti-interference. The existing algorithms cannot be adaptively applied to surface defect identification of the three steel products. A new method of adaptive multi-scale geometric analysis named RNAMlet was proposed. The idea of RNAMlet came from the non-symmetry anti-packing pattern representation model (NAM). The image is decomposed into a set of rectangular blocks asymmetrically according to gray value changes of image pixels. Then two-dimensional Haar wavelet transform is applied to all blocks. If the image background is complex, the number of blocks is large, and more details of the image are utilized. If the image background is simple, the number of blocks is small, and less computation time is needed. RNAMlet was tested with image samples of the three steel products, and compared with three classical methods of multi-scale geometric analysis, including Contourlet, Shearlet and Tetrolet. For the image samples with complicated backgrounds, such as continuous casting slabs and hot rolled steel plates, the defect identification rate obtained by RNAMlet was 1% higher than other three methods. For the image samples with simple backgrounds, such as cold rolled steel strips, the computation time of RNAMlet was one-tenth of the other three MGA methods, while the defect identification rates obtained by RNAMlet were higher than the other three methods.

Background Noises Versus Intraseasonal Variation Signals: Small vs. Large Convective Cloud Objects From CERES Aqua Observations

NASA Technical Reports Server (NTRS)

Xu, Kuan-Man

2015-01-01

During inactive phases of Madden-Julian Oscillation (MJO), there are plenty of deep but small convective systems and far fewer deep and large ones. During active phases of MJO, a manifestation of an increase in the occurrence of large and deep cloud clusters results from an amplification of large-scale motions by stronger convective heating. This study is designed to quantitatively examine the roles of small and large cloud clusters during the MJO life cycle. We analyze the cloud object data from Aqua CERES (Clouds and the Earth's Radiant Energy System) observations between July 2006 and June 2010 for tropical deep convective (DC) and cirrostratus (CS) cloud object types according to the real-time multivariate MJO index, which assigns the tropics to one of the eight MJO phases each day. The cloud object is a contiguous region of the earth with a single dominant cloud-system type. The criteria for defining these cloud types are overcast footprints and cloud top pressures less than 400 hPa, but DC has higher cloud optical depths (=10) than those of CS (<10). The size distributions, defined as the footprint numbers as a function of cloud object diameters, for particular MJO phases depart greatly from the combined (8-phase) distribution at large cloud-object diameters due to the reduced/increased numbers of cloud objects related to changes in the large-scale environments. The medium diameter corresponding to the combined distribution is determined and used to partition all cloud objects into "small" and "large" groups of a particular phase. The two groups corresponding to the combined distribution have nearly equal numbers of footprints. The medium diameters are 502 km for DC and 310 km for cirrostratus. The range of the variation between two extreme phases (typically, the most active and depressed phases) for the small group is 6-11% in terms of the numbers of cloud objects and the total footprint numbers. The corresponding range for the large group is 19-44%. In terms of the probability density functions of radiative and cloud physical properties, there are virtually no differences between the MJO phases for the small group, but there are significant differences for the large groups for both DC and CS types. These results suggest that the intreseasonal variation signals reside at the large cloud clusters while the small cloud clusters represent the background noises resulting from various types of the tropical waves with different wavenumbers and propagation speeds/directions.