The cosmic web in our own backyard.

PubMed

Ibata, Rodrigo A; Lewis, Geraint F

2008-01-04

On the largest scales, matter is strung out on an intricate pattern known as the cosmic web. The tendrils of this web should reach right into our own cosmic backyard, lacing the Galactic halo with lumps of dark matter. The search for these lumps, lit up by stars that formed within them, is a major astronomical endeavor, although it has failed to find the huge expected population. Is this a dark matter crisis, or does it provide clues to the complexities of gas physics in the early universe? New technologies in the coming decade will reveal the answer.

Revealing the Cosmic Web-dependent Halo Bias

NASA Astrophysics Data System (ADS)

Yang, Xiaohu; Zhang, Youcai; Lu, Tianhuan; Wang, Huiyuan; Shi, Feng; Tweed, Dylan; Li, Shijie; Luo, Wentao; Lu, Yi; Yang, Lei

2017-10-01

Halo bias is the one of the key ingredients of the halo models. It was shown at a given redshift to be only dependent, to the first order, on the halo mass. In this study, four types of cosmic web environments—clusters, filaments, sheets, and voids—are defined within a state-of-the-art high-resolution N-body simulation. Within these environments, we use both halo-dark matter cross correlation and halo-halo autocorrelation functions to probe the clustering properties of halos. The nature of the halo bias differs strongly between the four different cosmic web environments described here. With respect to the overall population, halos in clusters have significantly lower biases in the {10}11.0˜ {10}13.5 {h}-1 {M}⊙ mass range. In other environments, however, halos show extremely enhanced biases up to a factor 10 in voids for halos of mass ˜ {10}12.0 {h}-1 {M}⊙ . Such a strong cosmic web environment dependence in the halo bias may play an important role in future cosmological and galaxy formation studies. Within this cosmic web framework, the age dependency of halo bias is found to be only significant in clusters and filaments for relatively small halos ≲ {10}12.5 {h}-1 {M}⊙ .

Voids and the Cosmic Web: cosmic depression & spatial complexity

NASA Astrophysics Data System (ADS)

van de Weygaert, Rien

2016-10-01

Voids form a prominent aspect of the Megaparsec distribution of galaxies and matter. Not only do theyrepresent a key constituent of the Cosmic Web, they also are one of the cleanest probesand measures of global cosmological parameters. The shape and evolution of voids are highly sensitive tothe nature of dark energy, while their substructure and galaxy population provides a direct key to thenature of dark matter. Also, the pristine environment of void interiors is an important testing groundfor our understanding of environmental influences on galaxy formation and evolution. In this paper, we reviewthe key aspects of the structure and dynamics ofvoids, with a particular focus on the hierarchical evolution of the void population. We demonstratehow the rich structural pattern of the Cosmic Web is related to the complex evolution and buildupof voids.

Measuring Alignments between Galaxies and the Cosmic Web at z ˜ 2-3 Using IGM Tomography

NASA Astrophysics Data System (ADS)

Krolewski, Alex; Lee, Khee-Gan; Lukić, Zarija; White, Martin

2017-03-01

Many galaxy formation models predict alignments between galaxy spin and the cosmic web (I.e., directions of filaments and sheets), leading to an intrinsic alignment between galaxies that creates a systematic error in weak-lensing measurements. These effects are often predicted to be stronger at high redshifts (z ≳ 1) that are inaccessible to massive galaxy surveys on foreseeable instrumentation, but IGM tomography of the Lyα forest from closely spaced quasars and galaxies is starting to measure the z ˜ 2-3 cosmic web with requisite fidelity. Using mock surveys from hydrodynamical simulations, we examine the utility of this technique, in conjunction with coeval galaxy samples, to measure alignment between galaxies and the cosmic web at z ˜ 2.5. We show that IGM tomography surveys with ≲5 h -1 Mpc sightline spacing can accurately recover the eigenvectors of the tidal tensor, which we use to define the directions of the cosmic web. For galaxy spins and shapes, we use a model parameterized by the alignment strength, {{Δ }}< \\cos θ > , with respect to the tidal tensor eigenvectors from the underlying density field, and also consider observational effects such as errors in the galaxy position angle, inclination, and redshift. Measurements using the upcoming ˜1 deg2 CLAMATO tomographic survey and 600 coeval zCOSMOS-Deep galaxies should place 3σ limits on extreme alignment models with {{Δ }}< \\cos θ > ˜ 0.1, but much larger surveys encompassing >10,000 galaxies, such as Subaru PFS, will be required to constrain models with {{Δ }}< \\cos θ > ˜ 0.03. These measurements will constrain models of galaxy-cosmic web alignment and test tidal torque theory at z ˜ 2, improving our understanding of the physics of intrinsic alignments.

Measuring Alignments between Galaxies and the Cosmic Web at z ~ 2–3 Using IGM Tomography

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

Krolewski, Alex; Lee, Khee-Gan; Luki?, Zarija

Many galaxy formation models predict alignments between galaxy spin and the cosmic web (i.e., directions of filaments and sheets), leading to an intrinsic alignment between galaxies that creates a systematic error in weak-lensing measurements. These effects are often predicted to be stronger at high redshifts (z ≳ 1) that are inaccessible to massive galaxy surveys on foreseeable instrumentation, but IGM tomography of the Lyα forest from closely spaced quasars and galaxies is starting to measure the z ~ 2-3 cosmic web with requisite fidelity. Using mock surveys from hydrodynamical simulations, we examine the utility of this technique, in conjunction withmore » coeval galaxy samples, to measure alignment between galaxies and the cosmic web at z ~ 2.5. We show that IGM tomography surveys with ≲ 5 h -1 Mpc sightline spacing can accurately recover the eigenvectors of the tidal tensor, which we use to define the directions of the cosmic web. For galaxy spins and shapes, we use a model parameterized by the alignment strength, Δ (cos θ), with respect to the tidal tensor eigenvectors from the underlying density field, and also consider observational effects such as errors in the galaxy position angle, inclination, and redshift. Measurements using the upcoming ~ 1 deg 2 CLAMATO tomographic survey and 600 coeval zCOSMOS-Deep galaxies should place 3σ limits on extreme alignment models with Δ (cos θ) ~ 0.1, but much larger surveys encompassing > 10,000 galaxies, such as Subaru PFS, will be required to constrain models with Δ (cos θ) ~ 0.3. These measurements will constrain models of galaxy-cosmic web alignment and test tidal torque theory at z ~ 2, improving our understanding of the physics of intrinsic alignments.« less

Measuring Alignments between Galaxies and the Cosmic Web at z ~ 2–3 Using IGM Tomography

DOE PAGES

Krolewski, Alex; Lee, Khee-Gan; Luki?, Zarija; ...

2017-02-28

Many galaxy formation models predict alignments between galaxy spin and the cosmic web (i.e., directions of filaments and sheets), leading to an intrinsic alignment between galaxies that creates a systematic error in weak-lensing measurements. These effects are often predicted to be stronger at high redshifts (z ≳ 1) that are inaccessible to massive galaxy surveys on foreseeable instrumentation, but IGM tomography of the Lyα forest from closely spaced quasars and galaxies is starting to measure the z ~ 2-3 cosmic web with requisite fidelity. Using mock surveys from hydrodynamical simulations, we examine the utility of this technique, in conjunction withmore » coeval galaxy samples, to measure alignment between galaxies and the cosmic web at z ~ 2.5. We show that IGM tomography surveys with ≲ 5 h -1 Mpc sightline spacing can accurately recover the eigenvectors of the tidal tensor, which we use to define the directions of the cosmic web. For galaxy spins and shapes, we use a model parameterized by the alignment strength, Δ (cos θ), with respect to the tidal tensor eigenvectors from the underlying density field, and also consider observational effects such as errors in the galaxy position angle, inclination, and redshift. Measurements using the upcoming ~ 1 deg 2 CLAMATO tomographic survey and 600 coeval zCOSMOS-Deep galaxies should place 3σ limits on extreme alignment models with Δ (cos θ) ~ 0.1, but much larger surveys encompassing > 10,000 galaxies, such as Subaru PFS, will be required to constrain models with Δ (cos θ) ~ 0.3. These measurements will constrain models of galaxy-cosmic web alignment and test tidal torque theory at z ~ 2, improving our understanding of the physics of intrinsic alignments.« less

The topology of the cosmic web in terms of persistent Betti numbers

NASA Astrophysics Data System (ADS)

Pranav, Pratyush; Edelsbrunner, Herbert; van de Weygaert, Rien; Vegter, Gert; Kerber, Michael; Jones, Bernard J. T.; Wintraecken, Mathijs

2017-03-01

We introduce a multiscale topological description of the Megaparsec web-like cosmic matter distribution. Betti numbers and topological persistence offer a powerful means of describing the rich connectivity structure of the cosmic web and of its multiscale arrangement of matter and galaxies. Emanating from algebraic topology and Morse theory, Betti numbers and persistence diagrams represent an extension and deepening of the cosmologically familiar topological genus measure and the related geometric Minkowski functionals. In addition to a description of the mathematical background, this study presents the computational procedure for computing Betti numbers and persistence diagrams for density field filtrations. The field may be computed starting from a discrete spatial distribution of galaxies or simulation particles. The main emphasis of this study concerns an extensive and systematic exploration of the imprint of different web-like morphologies and different levels of multiscale clustering in the corresponding computed Betti numbers and persistence diagrams. To this end, we use Voronoi clustering models as templates for a rich variety of web-like configurations and the fractal-like Soneira-Peebles models exemplify a range of multiscale configurations. We have identified the clear imprint of cluster nodes, filaments, walls, and voids in persistence diagrams, along with that of the nested hierarchy of structures in multiscale point distributions. We conclude by outlining the potential of persistent topology for understanding the connectivity structure of the cosmic web, in large simulations of cosmic structure formation and in the challenging context of the observed galaxy distribution in large galaxy surveys.

Cosmology with the cosmic web

NASA Astrophysics Data System (ADS)

Forero-Romero, J. E.

2017-07-01

This talk summarizes different algorithms that can be used to trace the cosmic web both in simulations and observations. We present different applications in galaxy formation and cosmology. To finalize, we show how the Dark Energy Spectroscopic Instrument (DESI) could be a good place to apply these techniques.

Dependence of GAMA galaxy halo masses on the cosmic web environment from 100 deg2 of KiDS weak lensing data

NASA Astrophysics Data System (ADS)

Brouwer, Margot M.; Cacciato, Marcello; Dvornik, Andrej; Eardley, Lizzie; Heymans, Catherine; Hoekstra, Henk; Kuijken, Konrad; McNaught-Roberts, Tamsyn; Sifón, Cristóbal; Viola, Massimo; Alpaslan, Mehmet; Bilicki, Maciej; Bland-Hawthorn, Joss; Brough, Sarah; Choi, Ami; Driver, Simon P.; Erben, Thomas; Grado, Aniello; Hildebrandt, Hendrik; Holwerda, Benne W.; Hopkins, Andrew M.; de Jong, Jelte T. A.; Liske, Jochen; McFarland, John; Nakajima, Reiko; Napolitano, Nicola R.; Norberg, Peder; Peacock, John A.; Radovich, Mario; Robotham, Aaron S. G.; Schneider, Peter; Sikkema, Gert; van Uitert, Edo; Verdoes Kleijn, Gijs; Valentijn, Edwin A.

2016-11-01

Galaxies and their dark matter haloes are part of a complex network of mass structures, collectively called the cosmic web. Using the tidal tensor prescription these structures can be classified into four cosmic environments: voids, sheets, filaments and knots. As the cosmic web may influence the formation and evolution of dark matter haloes and the galaxies they host, we aim to study the effect of these cosmic environments on the average mass of galactic haloes. To this end we measure the galaxy-galaxy lensing profile of 91 195 galaxies, within 0.039 < z < 0.263, from the spectroscopic Galaxy And Mass Assembly survey, using {˜ }100 ° ^2 of overlapping data from the Kilo-Degree Survey. In each of the four cosmic environments we model the contributions from group centrals, satellites and neighbouring groups to the stacked galaxy-galaxy lensing profiles. After correcting the lens samples for differences in the stellar mass distribution, we find no dependence of the average halo mass of central galaxies on their cosmic environment. We do find a significant increase in the average contribution of neighbouring groups to the lensing profile in increasingly dense cosmic environments. We show, however, that the observed effect can be entirely attributed to the galaxy density at much smaller scales (within 4 h-1 Mpc), which is correlated with the density of the cosmic environments. Within our current uncertainties we find no direct dependence of galaxy halo mass on their cosmic environment.

Dynamics of pairwise motions in the Cosmic Web

NASA Astrophysics Data System (ADS)

Hellwing, Wojciech A.

2016-10-01

We present results of analysis of the dark matter (DM) pairwise velocity statistics in different Cosmic Web environments. We use the DM velocity and density field from the Millennium 2 simulation together with the NEXUS+ algorithm to segment the simulation volume into voxels uniquely identifying one of the four possible environments: nodes, filaments, walls or cosmic voids. We show that the PDFs of the mean infall velocities v 12 as well as its spatial dependence together with the perpendicular and parallel velocity dispersions bear a significant signal of the large-scale structure environment in which DM particle pairs are embedded. The pairwise flows are notably colder and have smaller mean magnitude in wall and voids, when compared to much denser environments of filaments and nodes. We discuss on our results, indicating that they are consistent with a simple theoretical predictions for pairwise motions as induced by gravitational instability mechanism. Our results indicate that the Cosmic Web elements are coherent dynamical entities rather than just temporal geometrical associations. In addition it should be possible to observationally test various Cosmic Web finding algorithms by segmenting available peculiar velocity data and studying resulting pairwise velocity statistics.

Null Environmental Effects of the Cosmic Web on Dark Matter Halo Properties

NASA Astrophysics Data System (ADS)

Goh, Tze; Primack, Joel; Aragon-Calvo, Miguel; Hellinger, Doug; Rodriguez-Puebla, Aldo; Lee, Christoph; Eckleholm, Elliot; Johnston, Kathryn

2018-01-01

We study the effects of the cosmic web environment (filaments, voids and walls) and environmental density on key properties of dark matter halos at redshift z = 0 using the Bolshoi-Planck ΛCDM. The z=0 Bolshoi-Planck simulation is analysed into filaments, voids and walls using the SpineWeb method, as well as VIDE method, both of which use Voronoi tessellation and the watershed transform. The key halo properties that we study are the mass accretion rate, spin parameter, concentration, prolateness, scale factor of the last major merger, and scale factor when the halo had half of its z=0 mass. For all these properties, we find that there is no discernible difference between the halo properties in filaments, walls or voids when compared at the same environmental density. As a result, we conclude that environmental density is the core attribute that affects these properties. This conclusion is in line with recent findings that properties of galaxies in redshift surveys are independent of their cosmic web environment at the same environmental density. We also find that the local web environment of the Milky Way and the Andromeda galaxy near the centre of a cosmic wall does not appear to have any effect on the key properties of these galaxies' dark matter halos, although we find that it is rather rare to have such massive halos near the centre of a relatively small cosmic wall.

Cosmic web and environmental dependence of screening: Vainshtein vs. chameleon

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

Falck, Bridget; Koyama, Kazuya; Zhao, Gong-Bo, E-mail: bridget.falck@port.ac.uk, E-mail: kazuya.koyama@port.ac.uk, E-mail: gong-bo.zhao@port.ac.uk

Theories which modify general relativity to explain the accelerated expansion of the Universe often use screening mechanisms to satisfy constraints on Solar System scales. We investigate the effects of the cosmic web and the local environmental density of dark matter halos on the screening properties of the Vainshtein and chameleon screening mechanisms. We compare the cosmic web morphology of dark matter particles, mass functions of dark matter halos, mass and radial dependence of screening, velocity dispersions and peculiar velocities, and environmental dependence of screening mechanisms in f(R) and nDGP models. Using the ORIGAMI cosmic web identification routine we find thatmore » the Vainshtein mechanism depends on the cosmic web morphology of dark matter particles, since these are defined according to the dimensionality of their collapse, while the chameleon mechanism shows no morphology dependence. The chameleon screening of halos and their velocity dispersions depend on halo mass, and small halos and subhalos can be environmentally screened in the chameleon mechanism. On the other hand, the screening of halos in the Vainshtein mechanism does not depend on mass nor environment, and their velocity dispersions are suppressed. The peculiar velocities of halos in the Vainshtein mechanism are enhanced because screened objects can still feel the fifth force generated by external fields, while peculiar velocities of chameleon halos are suppressed when the halo centers are screened.« less

Orientation of cosmic web filaments with respect to the underlying velocity field

NASA Astrophysics Data System (ADS)

Tempel, E.; Libeskind, N. I.; Hoffman, Y.; Liivamägi, L. J.; Tamm, A.

2014-01-01

The large-scale structure of the Universe is characterized by a web-like structure made of voids, sheets, filaments and knots. The structure of this so-called cosmic web is dictated by the local velocity shear tensor. In particular, the local direction of a filament should be strongly aligned with hat{e}_3, the eigenvector associated with the smallest eigenvalue of the tensor. That conjecture is tested here on the basis of a cosmological simulation. The cosmic web delineated by the halo distribution is probed by a marked point process with interactions (the Bisous model), detecting filaments directly from the halo distribution (P-web). The detected P-web filaments are found to be strongly aligned with the local hat{e}_3: the alignment is within 30° for ˜80 per cent of the elements. This indicates that large-scale filaments defined purely from the distribution of haloes carry more than just morphological information, although the Bisous model does not make any prior assumption on the underlying shear tensor. The P-web filaments are also compared to the structure revealed from the velocity shear tensor itself (V-web). In the densest regions, the P- and V-web filaments overlap well (90 per cent), whereas in lower density regions, the P-web filaments preferentially mark sheets in the V-web.

Simulating the physical properties of dark matter and gas inside the cosmic web

NASA Astrophysics Data System (ADS)

Dolag, K.; Meneghetti, M.; Moscardini, L.; Rasia, E.; Bonaldi, A.

2006-08-01

Using the results of a high-resolution, cosmological hydrodynamical re-simulation of a supercluster-like region, we investigate the physical properties of the gas located along the filaments and bridges which constitute the so-called cosmic web. First, we analyse the main characteristics of the density, temperature and velocity fields, which have quite different distributions, reflecting the complex dynamics of the structure-formation process. Then we quantify the signals which originate from the matter in the filaments by considering different observables. Inside the cosmic web, we find that the halo density is about 10-14 times larger than cosmic mean; the bremsstrahlung X-ray surface brightness reaches at most 10-16 erg s-1 cm-2 arcmin-2 the Compton-y parameter due to the thermal Sunyaev-Zel'dovich effect is about 10-6 the reduced shear produced by the weak lensing effect is ~0.01-0.02. These results confirm the difficulty of an observational detection of the cosmic web. Finally, we find that projection effects of the filamentary network can affect the estimates of the properties of single clusters, increasing their X-ray luminosity by less than 10 per cent and their central Compton-y parameter by up to 30 per cent.

The Fabric of the Universe: Exploring the Cosmic Web in 3D Prints and Woven Textiles

NASA Astrophysics Data System (ADS)

Diemer, Benedikt; Facio, Isaac

2017-05-01

We introduce The Fabric of the Universe, an art and science collaboration focused on exploring the cosmic web of dark matter with unconventional techniques and materials. We discuss two of our projects in detail. First, we describe a pipeline for translating three-dimensional (3D) density structures from N-body simulations into solid surfaces suitable for 3D printing, and present prints of a cosmological volume and of the infall region around a massive cluster halo. In these models, we discover wall-like features that are invisible in two-dimensional projections. Going beyond the sheer visualization of simulation data, we undertake an exploration of the cosmic web as a three-dimensional woven textile. To this end, we develop experimental 3D weaving techniques to create sphere-like and filamentary shapes and radically simplify a region of the cosmic web into a set of filaments and halos. We translate the resulting tree structure into a series of commands that can be executed by a digital weaving machine, and present a large-scale textile installation.

How to disentangle the Cosmic Web?

NASA Astrophysics Data System (ADS)

Shandarin, Sergei; Medvedev, Mikhail

2015-04-01

The Cosmic Web is a complicated highly-entangled geometrical object formed from remarkably simple - Gaussian - initial conditions. The full complexity of the Web can be fully appreciated in the six-dimensional phase space only, which study is, however, impractical due to numerous reasons. Instead, we suggest to use Lagrangian submanifold, i.e., the mapping x = x(q) , where x and q are three dimensional vectors representing Eulerian and Lagrangian coordinates. Being fully equivalent in dynamical sense to the phase space, it has the advantage of being a single valued and also metric space. In addition, we propose a new computational paradigm for the analysis of substructure of the Cosmic Web in cosmological cold dark matter (CDM) simulations. We introduce a new data-field - the flip-flop field - which carries wealth of information about the history and dynamics of the structure formation in the universe. The flip-flop (FF) field is an ordered data set in Lagrangian space representing the number of sign reversals of an elementary volume of each collisionless fluid element represented by a computational particle in a N-body simulation. This FF-field is effectively a multi-stream counter of each substructure element of the Cosmic Web. We demonstrate that the very rich subst Partially supported by DOE Grant DE-FG02-07ER54940 and NSF Grant AST-1209665.

Evolution of the Cosmic Web

NASA Astrophysics Data System (ADS)

Einasto, J.

2017-07-01

In the evolution of the cosmic web dark energy plays an important role. To understand the role of dark energy we investigate the evolution of superclusters in four cosmological models: standard model SCDM, conventional model LCDM, open model OCDM, and a hyper-dark-energy model HCDM. Numerical simulations of the evolution are performed in a box of size 1024 Mpc/h. Model superclusters are compared with superclusters found for Sloan Digital Sky Survey (SDSS). Superclusters are searched using density fields. LCDM superclusters have properties, very close to properties of observed SDSS superclusters. Standard model SCDM has about 2 times more superclusters than other models, but SCDM superclusters are smaller and have lower luminosities. Superclusters as principal structural elements of the cosmic web are present at all cosmological epochs.

A cosmic web filament revealed in Lyman-α emission around a luminous high-redshift quasar.

PubMed

Cantalupo, Sebastiano; Arrigoni-Battaia, Fabrizio; Prochaska, J Xavier; Hennawi, Joseph F; Madau, Piero

2014-02-06

Simulations of structure formation in the Universe predict that galaxies are embedded in a 'cosmic web', where most baryons reside as rarefied and highly ionized gas. This material has been studied for decades in absorption against background sources, but the sparseness of these inherently one-dimensional probes preclude direct constraints on the three-dimensional morphology of the underlying web. Here we report observations of a cosmic web filament in Lyman-α emission, discovered during a survey for cosmic gas fluorescently illuminated by bright quasars at redshift z ≈ 2.3. With a linear projected size of approximately 460 physical kiloparsecs, the Lyman-α emission surrounding the radio-quiet quasar UM 287 extends well beyond the virial radius of any plausible associated dark-matter halo and therefore traces intergalactic gas. The estimated cold gas mass of the filament from the observed emission-about 10(12.0 ± 0.5)/C(1/2) solar masses, where C is the gas clumping factor-is more than ten times larger than what is typically found in cosmological simulations, suggesting that a population of intergalactic gas clumps with subkiloparsec sizes may be missing in current numerical models.

Disentangling the Cosmic Web with Lagrangian Submanifold

NASA Astrophysics Data System (ADS)

Shandarin, Sergei F.; Medvedev, Mikhail V.

2016-10-01

The Cosmic Web is a complicated highly-entangled geometrical object. Remarkably it has formed from practically Gaussian initial conditions, which may be regarded as the simplest departure from exactly uniform universe in purely deterministic mapping. The full complexity of the web is revealed neither in configuration no velocity spaces considered separately. It can be fully appreciated only in six-dimensional (6D) phase space. However, studies of the phase space is complicated by the fact that every projection of it on a three-dimensional (3D) space is multivalued and contained caustics. In addition phase space is not a metric space that complicates studies of geometry. We suggest to use Lagrangian submanifold i.e., x = x(q), where both x and q are 3D vectors instead of the phase space for studies the complexity of cosmic web in cosmological N-body dark matter simulations. Being fully equivalent in dynamical sense to the phase space it has an advantage of being a single valued and also metric space.

Bayesian analysis of the dynamic cosmic web in the SDSS galaxy survey

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

Leclercq, Florent; Wandelt, Benjamin; Jasche, Jens, E-mail: florent.leclercq@polytechnique.org, E-mail: jasche@iap.fr, E-mail: wandelt@iap.fr

Recent application of the Bayesian algorithm \\textsc(borg) to the Sloan Digital Sky Survey (SDSS) main sample galaxies resulted in the physical inference of the formation history of the observed large-scale structure from its origin to the present epoch. In this work, we use these inferences as inputs for a detailed probabilistic cosmic web-type analysis. To do so, we generate a large set of data-constrained realizations of the large-scale structure using a fast, fully non-linear gravitational model. We then perform a dynamic classification of the cosmic web into four distinct components (voids, sheets, filaments, and clusters) on the basis of themore » tidal field. Our inference framework automatically and self-consistently propagates typical observational uncertainties to web-type classification. As a result, this study produces accurate cosmographic classification of large-scale structure elements in the SDSS volume. By also providing the history of these structure maps, the approach allows an analysis of the origin and growth of the early traces of the cosmic web present in the initial density field and of the evolution of global quantities such as the volume and mass filling fractions of different structures. For the problem of web-type classification, the results described in this work constitute the first connection between theory and observations at non-linear scales including a physical model of structure formation and the demonstrated capability of uncertainty quantification. A connection between cosmology and information theory using real data also naturally emerges from our probabilistic approach. Our results constitute quantitative chrono-cosmography of the complex web-like patterns underlying the observed galaxy distribution.« less

Evolution of the cosmic web

NASA Astrophysics Data System (ADS)

Cautun, Marius; van de Weygaert, Rien; Jones, Bernard J. T.; Frenk, Carlos S.

2014-07-01

The cosmic web is the largest scale manifestation of the anisotropic gravitational collapse of matter. It represents the transitional stage between linear and non-linear structures and contains easily accessible information about the early phases of structure formation processes. Here we investigate the characteristics and the time evolution of morphological components. Our analysis involves the application of the NEXUS Multiscale Morphology Filter technique, predominantly its NEXUS+ version, to high resolution and large volume cosmological simulations. We quantify the cosmic web components in terms of their mass and volume content, their density distribution and halo populations. We employ new analysis techniques to determine the spatial extent of filaments and sheets, like their total length and local width. This analysis identifies clusters and filaments as the most prominent components of the web. In contrast, while voids and sheets take most of the volume, they correspond to underdense environments and are devoid of group-sized and more massive haloes. At early times the cosmos is dominated by tenuous filaments and sheets, which, during subsequent evolution, merge together, such that the present-day web is dominated by fewer, but much more massive, structures. The analysis of the mass transport between environments clearly shows how matter flows from voids into walls, and then via filaments into cluster regions, which form the nodes of the cosmic web. We also study the properties of individual filamentary branches, to find long, almost straight, filaments extending to distances larger than 100 h-1 Mpc. These constitute the bridges between massive clusters, which seem to form along approximatively straight lines.

THE LOCAL GROUP IN THE COSMIC WEB

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

Forero-Romero, J. E.; González, R., E-mail: je.forero@uniandes.edu.co, E-mail: regonzar@astro.puc.cl

We explore the characteristics of the cosmic web around Local-Group (LG)-like pairs using a cosmological simulation in the ΛCDM cosmology. We use the Hessian of the gravitational potential to classify regions on scales of ∼2 Mpc as a peak, sheet, filament, or void. The sample of LG counterparts is represented by two samples of halo pairs. The first is a general sample composed of pairs with similar masses and isolation criteria as observed for the LG. The second is a subset with additional observed kinematic constraints such as relative pair velocity and separation. We find that the pairs in the LGmore » sample with all constraints are: (1) preferentially located in filaments and sheets, (2) located in a narrow range of local overdensity 0 < δ < 2, web ellipticity 0.1 < e < 1.0, and prolateness –0.4 < p < 0.4, (3) strongly aligned with the cosmic web. The alignments are such that the pair orbital angular momentum tends to be perpendicular to the smallest tidal eigenvector, e-hat {sub 3}, which lies along the filament direction or the sheet plane. A stronger alignment is present for the vector linking the two halos with the vector e-hat {sub 3}. Additionally, we fail to find a strong correlation between the spin of each halo in the pair with the cosmic web. All of these trends are expected to a great extent from the selection of LG total mass in the general sample. Applied to the observed LG, there is a potential conflict between the alignments of the different satellite planes and the numerical evidence for satellite accretion along filaments; the direction defined by e-hat {sub 3}. This highlights the relevance of achieving a precise characterization for the location of the LG in the cosmic web in the cosmological context provided by ΛCDM.« less

Dancing in the dark: galactic properties trace spin swings along the cosmic web

NASA Astrophysics Data System (ADS)

Dubois, Y.; Pichon, C.; Welker, C.; Le Borgne, D.; Devriendt, J.; Laigle, C.; Codis, S.; Pogosyan, D.; Arnouts, S.; Benabed, K.; Bertin, E.; Blaizot, J.; Bouchet, F.; Cardoso, J.-F.; Colombi, S.; de Lapparent, V.; Desjacques, V.; Gavazzi, R.; Kassin, S.; Kimm, T.; McCracken, H.; Milliard, B.; Peirani, S.; Prunet, S.; Rouberol, S.; Silk, J.; Slyz, A.; Sousbie, T.; Teyssier, R.; Tresse, L.; Treyer, M.; Vibert, D.; Volonteri, M.

2014-10-01

A large-scale hydrodynamical cosmological simulation, Horizon-AGN, is used to investigate the alignment between the spin of galaxies and the cosmic filaments above redshift 1.2. The analysis of more than 150 000 galaxies per time step in the redshift range 1.2 < z < 1.8 with morphological diversity shows that the spin of low-mass blue galaxies is preferentially aligned with their neighbouring filaments, while high-mass red galaxies tend to have a perpendicular spin. The reorientation of the spin of massive galaxies is provided by galaxy mergers, which are significant in their mass build-up. We find that the stellar mass transition from alignment to misalignment happens around 3 × 1010 M⊙. Galaxies form in the vorticity-rich neighbourhood of filaments, and migrate towards the nodes of the cosmic web as they convert their orbital angular momentum into spin. The signature of this process can be traced to the properties of galaxies, as measured relative to the cosmic web. We argue that a strong source of feedback such as active galactic nuclei is mandatory to quench in situ star formation in massive galaxies and promote various morphologies. It allows mergers to play their key role by reducing post-merger gas inflows and, therefore, keeping spins misaligned with cosmic filaments.

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.

The cosmic spiderweb: equivalence of cosmic, architectural and origami tessellations

PubMed Central

Hidding, Johan; Konstantatou, Marina; van de Weygaert, Rien

2018-01-01

For over 20 years, the term ‘cosmic web’ has guided our understanding of the large-scale arrangement of matter in the cosmos, accurately evoking the concept of a network of galaxies linked by filaments. But the physical correspondence between the cosmic web and structural engineering or textile ‘spiderwebs’ is even deeper than previously known, and also extends to origami tessellations. Here, we explain that in a good structure-formation approximation known as the adhesion model, threads of the cosmic web form a spiderweb, i.e. can be strung up to be entirely in tension. The correspondence is exact if nodes sampling voids are included, and if structure is excluded within collapsed regions (walls, filaments and haloes), where dark-matter multistreaming and baryonic physics affect the structure. We also suggest how concepts arising from this link might be used to test cosmological models: for example, to test for large-scale anisotropy and rotational flows in the cosmos. PMID:29765637

Dwarf Galaxies and the Cosmic Web

NASA Astrophysics Data System (ADS)

Benítez-Llambay, Alejandro; Navarro, Julio F.; Abadi, Mario G.; Gottlöber, Stefan; Yepes, Gustavo; Hoffman, Yehuda; Steinmetz, Matthias

2013-02-01

We use a cosmological simulation of the formation of the Local Group of Galaxies to identify a mechanism that enables the removal of baryons from low-mass halos without appealing to feedback or reionization. As the Local Group forms, matter bound to it develops a network of filaments and pancakes. This moving web of gas and dark matter drifts and sweeps a large volume, overtaking many halos in the process. The dark matter content of these halos is unaffected but their gas can be efficiently removed by ram pressure. The loss of gas is especially pronounced in low-mass halos due to their lower binding energy and has a dramatic effect on the star formation history of affected systems. This "cosmic web stripping" may help to explain the scarcity of dwarf galaxies compared with the numerous low-mass halos expected in ΛCDM and the large diversity of star formation histories and morphologies characteristic of faint galaxies. Although our results are based on a single high-resolution simulation, it is likely that the hydrodynamical interaction of dwarf galaxies with the cosmic web is a crucial ingredient so far missing from galaxy formation models.

The Global Sensor Web: A Platform for Citizen Science (Invited)

NASA Astrophysics Data System (ADS)

Simons, A. L.

2013-12-01

The Global Sensor Web (GSW) is an effort to provide an infrastructure for the collection, sharing and visualizing sensor data from around the world. Over the past three years the GSW has been developed and tested as a standardized platform for citizen science. The most developed of the citizen science projects built onto the GSW has been Distributed Electronic Cosmic-ray Observatory (DECO), which is an Android application designed to harness a global network of mobile devices, to detect the origin and behavior of the cosmic radiation. Other projects which can be readily built on top of GSW as a platform are also discussed. A cosmic-ray track candidate captured on a cell phone camera.

Turning Around along the Cosmic Web

NASA Astrophysics Data System (ADS)

Lee, Jounghun; Yepes, Gustavo

2016-12-01

A bound violation designates a case in which the turnaround radius of a bound object exceeds the upper limit imposed by the spherical collapse model based on the standard ΛCDM paradigm. Given that the turnaround radius of a bound object is a stochastic quantity and that the spherical model overly simplifies the true gravitational collapse, which actually proceeds anisotropically along the cosmic web, the rarity of the occurrence of a bound violation may depend on the web environment. Assuming a Planck cosmology, we numerically construct the bound-zone peculiar velocity profiles along the cosmic web (filaments and sheets) around the isolated groups with virial mass {M}{{v}}≥slant 3× {10}13 {h}-1 {M}⊙ identified in the Small MultiDark Planck simulations and determine the radial distances at which their peculiar velocities equal the Hubble expansion speed as the turnaround radii of the groups. It is found that although the average turnaround radii of the isolated groups are well below the spherical bound limit on all mass scales, the bound violations are not forbidden for individual groups, and the cosmic web has an effect of reducing the rarity of the occurrence of a bound violation. Explaining that the spherical bound limit on the turnaround radius in fact represents the threshold distance up to which the intervention of the external gravitational field in the bound-zone peculiar velocity profiles around the nonisolated groups stays negligible, we discuss the possibility of using the threshold distance scale to constrain locally the equation of state of dark energy.

The Hubble Web: The Dark Matter Problem and Cosmic Strings

NASA Astrophysics Data System (ADS)

Alexander, Stephon

2009-07-01

I propose a reinterpretation of cosmic dark matter in which a rigid network of cosmic strings formed at the end of inflation. The cosmic strings fulfill three functions: At recombination they provide an accretion mechanism for virializing baryonic and warm dark matter into disks. These cosmic strings survive as configurations which thread spiral and elliptical galaxies leading to the observed flatness of rotation curves and the Tully-Fisher relation. We find a relationship between the rotational velocity of the galaxy and the string tension and discuss the testability of this model.

NEXUS: tracing the cosmic web connection

NASA Astrophysics Data System (ADS)

Cautun, Marius; van de Weygaert, Rien; Jones, Bernard J. T.

2013-02-01

We introduce the NEXUS algorithm for the identification of cosmic web environments: clusters, filaments, walls and voids. This is a multiscale and automatic morphological analysis tool that identifies all the cosmic structures in a scale free way, without preference for a certain size or shape. We develop the NEXUS method to incorporate the density, tidal field, velocity divergence and velocity shear as tracers of the cosmic web. We also present the NEXUS+ procedure which, taking advantage of a novel filtering of the density in logarithmic space, is very successful at identifying the filament and wall environments in a robust and natural way. To assess the algorithms we apply them to an N-body simulation. We find that all methods correctly identify the most prominent filaments and walls, while there are differences in the detection of the more tenuous structures. In general, the structures traced by the density and tidal fields are clumpier and more rugged than those present in the velocity divergence and velocity shear fields. We find that the NEXUS+ method captures much better the filamentary and wall networks and is successful in detecting even the fainter structures. We also confirm the efficiency of our methods by examining the dark matter particle and halo distributions.

Exploring the Extreme Universe! (2nd Edition)

NASA Technical Reports Server (NTRS)

White, Nicholas E.

2002-01-01

A large array of web sites devoted to the science that the NASA Goddard Space Flight Center Laboratory for High Energy Astrophysics (LHEA) studies have been frozen in time and included on this CD. Featured are five of our 'Understanding the Extreme Universe' sites, which offer explanations about cosmic ray, gamma ray, and X-ray science and satellites, as well as cosmic distances. They also include images and engaging activities that are great for helping both children and adults to learn more about science and basic physical principles. The 'Missions That Take Us There' section contains web sites on the satellite, balloon-borne, International Space Station, and rocket missions in our Laboratory that study X-rays, gamma rays, and cosmic rays. There are also two multi-mission sites and an experiment that measures Earth's UV light in preparation for a future cosmic ray mission. Most of the sites on this CD contain high-resolution images that are great for scientific presentations, study, or just your own enjoyment. This CD shows our web sites as they existed in April of 2001. We have made sure to include the WWW address for every site, so you will know where to go to access the most current versions of them.

One dark matter mystery: halos in the cosmic web

NASA Astrophysics Data System (ADS)

Gaite, Jose

2015-01-01

The current cold dark matter cosmological model explains the large scale cosmic web structure but is challenged by the observation of a relatively smooth distribution of matter in galactic clusters. We consider various aspects of modeling the dark matter around galaxies as distributed in smooth halos and, especially, the smoothness of the dark matter halos seen in N-body cosmological simulations. We conclude that the problems of the cold dark matter cosmology on small scales are more serious than normally admitted.

Multipolar moments of weak lensing signal around clusters. Weighing filaments in harmonic space

NASA Astrophysics Data System (ADS)

Gouin, C.; Gavazzi, R.; Codis, S.; Pichon, C.; Peirani, S.; Dubois, Y.

2017-09-01

Context. Upcoming weak lensing surveys such as Euclid will provide an unprecedented opportunity to quantify the geometry and topology of the cosmic web, in particular in the vicinity of lensing clusters. Aims: Understanding the connectivity of the cosmic web with unbiased mass tracers, such as weak lensing, is of prime importance to probe the underlying cosmology, seek dynamical signatures of dark matter, and quantify environmental effects on galaxy formation. Methods: Mock catalogues of galaxy clusters are extracted from the N-body PLUS simulation. For each cluster, the aperture multipolar moments of the convergence are calculated in two annuli (inside and outside the virial radius). By stacking their modulus, a statistical estimator is built to characterise the angular mass distribution around clusters. The moments are compared to predictions from perturbation theory and spherical collapse. Results: The main weakly chromatic excess of multipolar power on large scales is understood as arising from the contraction of the primordial cosmic web driven by the growing potential well of the cluster. Besides this boost, the quadrupole prevails in the cluster (ellipsoidal) core, while at the outskirts, harmonic distortions are spread on small angular modes, and trace the non-linear sharpening of the filamentary structures. Predictions for the signal amplitude as a function of the cluster-centric distance, mass, and redshift are presented. The prospects of measuring this signal are estimated for current and future lensing data sets. Conclusions: The Euclid mission should provide all the necessary information for studying the cosmic evolution of the connectivity of the cosmic web around lensing clusters using multipolar moments and probing unique signatures of, for example, baryons and warm dark matter.

Cluster outskirts and the missing baryons

NASA Astrophysics Data System (ADS)

Eckert, D.

2016-06-01

Galaxy clusters are located at the crossroads of intergalactic filaments and are still forming through the continuous merging and accretion of smaller structures from the surrounding cosmic web. Deep, wide-field X-ray studies of the outskirts of the most massive clusters bring us valuable insight into the processes leading to the growth of cosmic structures. In addition, cluster outskirts are privileged sites to search for the missing baryons, which are thought to reside within the filaments of the cosmic web. I will present the XMM cluster outskirts project, a VLP that aims at mapping the outskirts of 13 nearby clusters. Based on the results obtained with this program, I will then explore ideas to exploit the capabilities of XMM during the next decade.

The Cosmic V-Web

NASA Astrophysics Data System (ADS)

Pomarède, Daniel; Hoffman, Yehuda; Courtois, Hélène M.; Tully, R. Brent

2017-08-01

The network of filaments with embedded clusters surrounding voids, which has been seen in maps derived from redshift surveys and reproduced in simulations, has been referred to as the cosmic web. A complementary description is provided by considering the shear in the velocity field of galaxies. The eigenvalues of the shear provide information regarding whether or not a region is collapsing in three dimensions, which is the condition for a knot, expanding in three dimensions, which is the condition for a void, or in the intermediate condition of a filament or sheet. The structures that are quantitatively defined by the eigenvalues can be approximated by iso-contours that provide a visual representation of the cosmic velocity (V) web. The current application is based on radial peculiar velocities from the Cosmicflows-2 collection of distances. The three-dimensional velocity field is constructed using the Wiener filter methodology in the linear approximation. Eigenvalues of the velocity shear are calculated at each point on a grid. Here, knots and filaments are visualized across a local domain of diameter ˜ 0.1c.

Featured Image: The Cosmic Velocity Web

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2017-09-01

You may have heard of the cosmic web, a network of filaments, clusters and voids that describes the three-dimensional distribution of matter in our universe. But have you ever considered the idea of a cosmic velocity web? In a new study led by Daniel Pomarde (IRFU CEA-Saclay, France), a team of scientists has built a detailed 3D view of the flows in our universe, showing in particular motions along filaments and in collapsing knots. In the image above (click for the full view), surfaces of knots (red) are embedded within surfaces of filaments (grey). The rainbow lines show the flow motion, revealing acceleration (redder tones) toward knots and retardation (bluer tones) beyond them. You can learn more about Pomarde and collaborators work and see their unusual and intriguing visualizationsin the video they produced, below. Check out the original paper for more information.CitationDaniel Pomarde et al 2017 ApJ 845 55. doi:10.3847/1538-4357/aa7f78

Mapping Diffuse HI Content in MHONGOOSE Galaxies NGC 1744 and NGC 7424

NASA Astrophysics Data System (ADS)

Sardone, Amy; Pisano, Daniel J.; Pingel, Nickolas

2017-01-01

The universe contains an abundance of neutral atomic hydrogen, or HI. This HI holds the key to knowing how stars are born, how galaxies form and develop, and how dark matter halos accrete gas from the cosmic web. One of the most crucial questions regarding galaxy formation today is how galaxies accrete their gas and how accretion processes affect subsequent star formation. We are trying to answer these questions by mapping the HI content in a four square degree region around galaxies NGC 1744 and NGC 7424, galaxies to be observed as part of the MHONGOOSE survey. NGC 1744 has already been observed extensively with the VLA, so we will be able to quantify the differences in emission. To do this our GBT maps must be sensitive to column densities on the order of ~1018 cm-2. With such low column densities, we will be able to search for features of the cosmic web in the form of tidal interactions and cosmic web filaments with its relation to star-forming galaxies.

DWARF GALAXIES AND THE COSMIC WEB

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

Benitez-Llambay, Alejandro; Abadi, Mario G.; Navarro, Julio F.

2013-02-01

We use a cosmological simulation of the formation of the Local Group of Galaxies to identify a mechanism that enables the removal of baryons from low-mass halos without appealing to feedback or reionization. As the Local Group forms, matter bound to it develops a network of filaments and pancakes. This moving web of gas and dark matter drifts and sweeps a large volume, overtaking many halos in the process. The dark matter content of these halos is unaffected but their gas can be efficiently removed by ram pressure. The loss of gas is especially pronounced in low-mass halos due tomore » their lower binding energy and has a dramatic effect on the star formation history of affected systems. This 'cosmic web stripping' may help to explain the scarcity of dwarf galaxies compared with the numerous low-mass halos expected in {Lambda}CDM and the large diversity of star formation histories and morphologies characteristic of faint galaxies. Although our results are based on a single high-resolution simulation, it is likely that the hydrodynamical interaction of dwarf galaxies with the cosmic web is a crucial ingredient so far missing from galaxy formation models.« less

Unveiling the Synchrotron Cosmic Web: Pilot Study

NASA Astrophysics Data System (ADS)

Brown, Shea; Rudnick, Lawrence; Pfrommer, Christoph; Jones, Thomas

2011-10-01

The overall goal of this project is to challenge our current theoretical understanding of the relativistic particle populations in the inter-galactic medium (IGM) through deep 1.4 GHz observations of 13 massive, high-redshift clusters of galaxies. Designed to compliment/extend the GMRT radio halo survey (Venturi et al. 2007), these observations will attempt to detect the peaks of the purported synchrotron cosmic-web, and place serious limits on models of CR acceleration and magnetic field amplification during large-scale structure formation. The primary goals of this survey are: 1) Confirm the bi-modal nature of the radio halo population, which favors turbulent re-acceleration of cosmic-ray electrons (CRe) during cluster mergers as the source of the diffuse radio emission; 2) Directly test hadronic secondary models which predict the presence of cosmic-ray protons (CRp) in the cores of massive X-ray clusters; 3) Search in polarization for shock structures, a potential source of CR acceleration in the IGM.

New Perspectives: Wave Mechanical Interpretations of Dark Matter, Baryon and Dark Energy

NASA Astrophysics Data System (ADS)

Russell, Esra

We model the cosmic components: dark matter, dark energy and baryon distributions in the Cosmic Web by means of highly nonlinear Schrodinger type and reaction diffusion type wave mechanical descriptions. The construction of these wave mechanical models of the structure formation is achieved by introducing the Fisher information measure and its comparison with highly nonlinear term which has dynamical analogy to infamous quantum potential in the wave equations. Strikingly, the comparison of this nonlinear term and the Fisher information measure provides a dynamical distinction between lack of self-organization and self-organization in the dynamical evolution of the cosmic components. Mathematically equivalent to the standard cosmic fluid equations, these approaches make it possible to follow the evolution of the matter distribution even into the highly nonlinear regime by circumventing singularities. Also, numerical realizations of the emerging web-like patterns are presented from the nonlinear dynamics of the baryon component while dark energy component shows Gaussian type dynamics corresponding to soliton-like solutions.

The hierarchical nature of the spin alignment of dark matter haloes in filaments

NASA Astrophysics Data System (ADS)

Aragon-Calvo, M. A.; Yang, Lin Forrest

2014-05-01

Dark matter haloes in cosmological filaments and walls have (in average) their spin vector aligned with their host structure. While haloes in walls are aligned with the plane of the wall independently of their mass, haloes in filaments present a mass-dependent two-regime orientation. Here, we show that the transition mass determining the change in the alignment regime (from parallel to perpendicular) depends on the hierarchical level in which the halo is located, reflecting the hierarchical nature of the Cosmic Web. By explicitly exposing the hierarchical structure of the Cosmic Web, we are able to identify the contributions of different components of the filament network to the alignment signal. We propose a unifying picture of angular momentum acquisition that is based on the results presented here and previous results found by other authors. In order to do a hierarchical characterization of the Cosmic Web, we introduce a new implementation of the multiscale morphology filter, the MMF-2, that significantly improves the identification of structures and explicitly describes their hierarchy. L36

An Origami Approximation to the Cosmic Web

NASA Astrophysics Data System (ADS)

Neyrinck, Mark C.

2016-10-01

The powerful Lagrangian view of structure formation was essentially introduced to cosmology by Zel'dovich. In the current cosmological paradigm, a dark-matter-sheet 3D manifold, inhabiting 6D position-velocity phase space, was flat (with vanishing velocity) at the big bang. Afterward, gravity stretched and bunched the sheet together in different places, forming a cosmic web when projected to the position coordinates. Here, I explain some properties of an origami approximation, in which the sheet does not stretch or contract (an assumption that is false in general), but is allowed to fold. Even without stretching, the sheet can form an idealized cosmic web, with convex polyhedral voids separated by straight walls and filaments, joined by convex polyhedral nodes. The nodes form in `polygonal' or `polyhedral' collapse, somewhat like spherical/ellipsoidal collapse, except incorporating simultaneous filament and wall formation. The origami approximation allows phase-space geometries of nodes, filaments, and walls to be more easily understood, and may aid in understanding spin correlations between nearby galaxies. This contribution explores kinematic origami-approximation models giving velocity fields for the first time.

The cosmic web and the orientation of angular momenta

NASA Astrophysics Data System (ADS)

Libeskind, Noam I.; Hoffman, Yehuda; Knebe, Alexander; Steinmetz, Matthias; Gottlöber, Stefan; Metuki, Ofer; Yepes, Gustavo

2012-03-01

We use a 64 h-1 Mpc dark-matter-only cosmological simulation to examine the large-scale orientation of haloes and substructures with respect to the cosmic web. A web classification scheme based on the velocity shear tensor is used to assign to each halo in the simulation a web type: knot, filament, sheet or void. Using ˜106 haloes that span ˜3 orders of magnitude in mass, the orientation of the halo's spin and the orbital angular momentum of subhaloes with respect to the eigenvectors of the shear tensor is examined. We find that the orbital angular momentum of subhaloes tends to align with the intermediate eigenvector of the velocity shear tensor for all haloes in knots, filaments and sheets. This result indicates that the kinematics of substructures located deep within the virialized regions of a halo is determined by its infall which in turn is determined by the large-scale velocity shear, a surprising result given the virialized nature of haloes. The non-random nature of subhalo accretion is thus imprinted on the angular momentum measured at z= 0. We also find that the haloes' spin axis is aligned with the third eigenvector of the velocity shear tensor in filaments and sheets: the halo spin axis points along filaments and lies in the plane of cosmic sheets.

On the connectivity of the cosmic web: theory and implications for cosmology and galaxy formation

NASA Astrophysics Data System (ADS)

Codis, Sandrine; Pogosyan, Dmitri; Pichon, Christophe

2018-06-01

Cosmic connectivity and multiplicity, i.e. the number of filaments globally or locally connected to a given cluster is a natural probe of the growth of structure and in particular of the nature of dark energy. It is also a critical ingredient driving the assembly history of galaxies as it controls mass and angular momentum accretion. The connectivity of the cosmic web is investigated here via the persistent skeleton. This tool identifies topologically the ridges of the cosmic landscape which allows us to investigate how the nodes of the cosmic web are connected together. When applied to Gaussian random fields corresponding to the high redshift universe, it is found that on average the nodes are connected to exactly κ = 4 neighbours in two dimensions and ˜6.1 in three dimensions. Investigating spatial dimensions up to d = 6, typical departures from a cubic lattice κ = 2d are shown to scale like the power 7/4 of the dimension. These numbers strongly depend on the height of the peaks: the higher the peak the larger the connectivity. Predictions from first principles based on peak theory are shown to reproduce well the connectivity and multiplicity of Gaussian random fields and cosmological simulations. As an illustration, connectivity is quantified in galaxy lensing convergence maps and large dark haloes catalogues. As a function of redshift and scale the mean connectivity decreases in a cosmology-dependent way. As a function of halo mass it scales like 10/3 times the log of the mass. Implications on galactic scales are discussed.

The Lyα forest and the Cosmic Web

NASA Astrophysics Data System (ADS)

Meiksin, Avery

2016-10-01

The accurate description of the properties of the Lyman-α forest is a spectacular success of the Cold Dark Matter theory of cosmological structure formation. After a brief review of early models, it is shown how numerical simulations have demonstrated the Lyman-α forest emerges from the cosmic web in the quasi-linear regime of overdensity. The quasi-linear nature of the structures allows accurate modeling, providing constraints on cosmological models over a unique range of scales and enabling the Lyman-α forest to serve as a bridge to the more complex problem of galaxy formation.

Big Data of the Cosmic Web

NASA Astrophysics Data System (ADS)

Kitaura, Francisco-Shu

2016-10-01

One of the main goals in cosmology is to understand how the Universe evolves, how it forms structures, why it expands, and what is the nature of dark matter and dark energy. Next decade large and expensive observational projects will bring information on the structure and the distribution of many millions of galaxies at different redshifts enabling us to make great progress in answering these questions. However, these data require a very special and complex set of analysis tools to extract the maximum valuable information. Statistical inference techniques are being developed, bridging the gaps between theory, simulations, and observations. In particular, we discuss the efforts to address the question: What is the underlying nonlinear matter distribution and dynamics at any cosmic time corresponding to a set of observed galaxies in redshift space? An accurate reconstruction of the initial conditions encodes the full phase-space information at any later cosmic time (given a particular structure formation model and a set of cosmological parameters). We present advances to solve this problem in a self-consistent way with Big Data techniques of the Cosmic Web.

Relation between halo spin and cosmic-web filaments at z ≃ 3

NASA Astrophysics Data System (ADS)

González, Roberto E.; Prieto, Joaquin; Padilla, Nelson; Jimenez, Raul

2017-02-01

We investigate the spin evolution of dark matter haloes and their dependence on the number of connected filaments from the cosmic web at high redshift (spin-filament relation hereafter). To this purpose, we have simulated 5000 haloes in the mass range 5 × 109 h-1 M⊙ to 5 × 1011 h-1 M⊙ at z = 3 in cosmological N-body simulations. We confirm the relation found by Prieto et al. (2015) where haloes with fewer filaments have larger spin. We also found that this relation is more significant for higher halo masses, and for haloes with a passive (no major mergers) assembly history. Another finding is that haloes with larger spin or with fewer filaments have their filaments more perpendicularly aligned with the spin vector. Our results point to a picture in which the initial spin of haloes is well described by tidal torque theory and then gets subsequently modified in a predictable way because of the topology of the cosmic web, which in turn is given by the currently favoured Lambda cold dark matter (LCDM) model. Our spin-filament relation is a prediction from LCDM that could be tested with observations.

Intergalactic medium emission observations with the cosmic web imager. II. Discovery of extended, kinematically linked emission around SSA22 Lyα BLOB 2

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

Christopher Martin, D.; Chang, Daphne; Matuszewski, Matt

The intergalactic medium (IGM) is the dominant reservoir of baryons, delineates the large-scale structure of the universe at low to moderate overdensities, and provides gas from which galaxies form and evolve. Simulations of a cold-dark-matter- (CDM-) dominated universe predict that the IGM is distributed in a cosmic web of filaments and that galaxies should form along and at the intersections of these filaments. While observations of QSO absorption lines and the large-scale distribution of galaxies have confirmed the CDM paradigm, the cosmic web of IGM has never been confirmed by direct imaging. Here we report our observation of the Lyαmore » blob 2 (LAB2) in SSA22 with the Cosmic Web Imager (CWI). This is an integral field spectrograph optimized for low surface brightness, extended emission. With 22 hr of total on- and off-source exposure, CWI has revealed that LAB2 has extended Lyα emission that is organized into azimuthal zones consistent with filaments. We perform numerous tests with simulations and the data to secure the robustness of this result, which relies on data with modest signal-to-noise ratios. We have developed a smoothing algorithm that permits visualization of data cube slices along image or spectral image planes. With both raw and smoothed data cubes we demonstrate that the filaments are kinematically associated with LAB2 and display double-peaked profiles characteristic of optically thick Lyα emission. The flux is 10-20 times brighter than expected for the average emission from the IGM but is consistent with boosted fluorescence from a buried QSO or gravitation cooling radiation. Using simple emission models, we infer a baryon mass in the filaments of at least 1-4 × 10{sup 11} M {sub ☉}, and the dark halo mass is at least 2 × 10{sup 12} M {sub ☉}. The spatial-kinematic morphology is more consistent with inflow from the cosmic web than outflow from LAB2, although an outflow feature maybe present at one azimuth. LAB2 and the surrounding gas have significant and coaligned angular momentum, strengthening the case for their association.« less

A Novel Approach to Visualizing Dark Matter Simulations.

PubMed

Kaehler, R; Hahn, O; Abel, T

2012-12-01

In the last decades cosmological N-body dark matter simulations have enabled ab initio studies of the formation of structure in the Universe. Gravity amplified small density fluctuations generated shortly after the Big Bang, leading to the formation of galaxies in the cosmic web. These calculations have led to a growing demand for methods to analyze time-dependent particle based simulations. Rendering methods for such N-body simulation data usually employ some kind of splatting approach via point based rendering primitives and approximate the spatial distributions of physical quantities using kernel interpolation techniques, common in SPH (Smoothed Particle Hydrodynamics)-codes. This paper proposes three GPU-assisted rendering approaches, based on a new, more accurate method to compute the physical densities of dark matter simulation data. It uses full phase-space information to generate a tetrahedral tessellation of the computational domain, with mesh vertices defined by the simulation's dark matter particle positions. Over time the mesh is deformed by gravitational forces, causing the tetrahedral cells to warp and overlap. The new methods are well suited to visualize the cosmic web. In particular they preserve caustics, regions of high density that emerge, when several streams of dark matter particles share the same location in space, indicating the formation of structures like sheets, filaments and halos. We demonstrate the superior image quality of the new approaches in a comparison with three standard rendering techniques for N-body simulation data.

Cosmic Origins Program Annual Technology Report

NASA Technical Reports Server (NTRS)

Pham, Bruce Thai; Neff, Susan Gale

2016-01-01

What is the Cosmic Origins (COR) Program? From ancient times, humans have looked up at the night sky and wondered: Are we alone? How did the universe come to be? How does the universe work? COR focuses on the second question. Scientists investigating this broad theme seek to understand the origin and evolution of the universe from the Big Bang to the present day, determining how the expanding universe grew into a grand cosmic web of dark matter enmeshed with galaxies and pristine gas, forming, merging, and evolving over time.

Projects made with the Berkeley Lab Circuit Board

Science.gov Websites

dependence of cosmic rays. Greg Poe, a student at Travis High School in Richmond, Texas, received an the journal Physics Education. He used the Berkeley Lab circuit board together with spare parts from New York Schools Cosmic Particle Telescope workshop. Ken Cecire has created a web page which describes

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.

Nexus of the Cosmic Web

NASA Astrophysics Data System (ADS)

Cautun, Marius; van de Weygaert, Rien; Jones, Bernard J. T.; Frenk, Carlos S.; Hellwing, Wojciech A.

2015-01-01

One of the important unknowns of current cosmology concerns the effects of the large scale distribution of matter on the formation and evolution of dark matter haloes and galaxies. One main difficulty in answering this question lies in the absence of a robust and natural way of identifying the large scale environments and their characteristics. This work summarizes the NEXUS+ formalism which extends and improves our multiscale scale-space MMF method. The new algorithm is very successful in tracing the Cosmic Web components, mainly due to its novel filtering of the density in logarithmic space. The method, due to its multiscale and hierarchical character, has the advantage of detecting all the cosmic structures, either prominent or tenuous, without preference for a certain size or shape. The resulting filamentary and wall networks can easily be characterized by their direction, thickness, mass density and density profile. These additional environmental properties allows to us to investigate not only the effect of environment on haloes, but also how it correlates with the environment characteristics.

Warm-hot baryons comprise 5-10 per cent of filaments in the cosmic web.

PubMed

Eckert, Dominique; Jauzac, Mathilde; Shan, HuanYuan; Kneib, Jean-Paul; Erben, Thomas; Israel, Holger; Jullo, Eric; Klein, Matthias; Massey, Richard; Richard, Johan; Tchernin, Céline

2015-12-03

Observations of the cosmic microwave background indicate that baryons account for 5 per cent of the Universe's total energy content. In the local Universe, the census of all observed baryons falls short of this estimate by a factor of two. Cosmological simulations indicate that the missing baryons have not condensed into virialized haloes, but reside throughout the filaments of the cosmic web (where matter density is larger than average) as a low-density plasma at temperatures of 10(5)-10(7) kelvin, known as the warm-hot intergalactic medium. There have been previous claims of the detection of warm-hot baryons along the line of sight to distant blazars and of hot gas between interacting clusters. These observations were, however, unable to trace the large-scale filamentary structure, or to estimate the total amount of warm-hot baryons in a representative volume of the Universe. Here we report X-ray observations of filamentary structures of gas at 10(7) kelvin associated with the galaxy cluster Abell 2744. Previous observations of this cluster were unable to resolve and remove coincidental X-ray point sources. After subtracting these, we find hot gas structures that are coherent over scales of 8 megaparsecs. The filaments coincide with over-densities of galaxies and dark matter, with 5-10 per cent of their mass in baryonic gas. This gas has been heated up by the cluster's gravitational pull and is now feeding its core. Our findings strengthen evidence for a picture of the Universe in which a large fraction of the missing baryons reside in the filaments of the cosmic web.

The Vainshtein mechanism in the cosmic web

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

Falck, Bridget; Koyama, Kazuya; Zhao, Gong-bo

We investigate the dependence of the Vainshtein screening mechanism on the cosmic web morphology of both dark matter particles and halos as determined by ORIGAMI. Unlike chameleon and symmetron screening, which come into effect in regions of high density, Vainshtein screening instead depends on the dimensionality of the system, and screened bodies can still feel external fields. ORIGAMI is well-suited to this problem because it defines morphologies according to the dimensionality of the collapsing structure and does not depend on a smoothing scale or density threshold parameter. We find that halo particles are screened while filament, wall, and void particlesmore » are unscreened, and this is independent of the particle density. However, after separating halos according to their large scale cosmic web environment, we find no difference in the screening properties of halos in filaments versus halos in clusters. We find that the fifth force enhancement of dark matter particles in halos is greatest well outside the virial radius. We confirm the theoretical expectation that even if the internal field is suppressed by the Vainshtein mechanism, the object still feels the fifth force generated by the external fields, by measuring peculiar velocities and velocity dispersions of halos. Finally, we investigate the morphology and gravity model dependence of halo spins, concentrations, and shapes.« less

Cosmic web and star formation activity in galaxies at z ∼ 1

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

Darvish, B.; Mobasher, B.; Sales, L. V.

We investigate the role of the delineated cosmic web/filaments on star formation activity by exploring a sample of 425 narrow-band selected Hα emitters, as well as 2846 color-color selected underlying star-forming galaxies for a large-scale structure at z = 0.84 in the COSMOS field from the HiZELS survey. Using the scale-independent Multi-scale Morphology Filter algorithm, we are able to quantitatively describe the density field and disentangle it into its major components: fields, filaments, and clusters. We show that the observed median star formation rate (SFR), stellar mass, specific SFR, the mean SFR-mass relation, and its scatter for both Hα emittersmore » and underlying star-forming galaxies do not strongly depend on different classes of environment, in agreement with previous studies. However, the fraction of Hα emitters varies with environment and is enhanced in filamentary structures at z ∼ 1. We propose mild galaxy-galaxy interactions as the possible physical agent for the elevation of the fraction of Hα star-forming galaxies in filaments. Our results show that filaments are the likely physical environments that are often classed as the 'intermediate' densities and that the cosmic web likely plays a major role in galaxy formation and evolution which has so far been poorly investigated.« less

Low-frequency radio constraints on the synchrotron cosmic web

NASA Astrophysics Data System (ADS)

Vernstrom, T.; Gaensler, B. M.; Brown, S.; Lenc, E.; Norris, R. P.

2017-06-01

We present a search for the synchrotron emission from the synchrotron cosmic web by cross-correlating 180-MHz radio images from the Murchison Widefield Array with tracers of large-scale structure (LSS). We use two versions of the radio image covering 21.76° × 21.76° with point sources brighter than 0.05 Jy subtracted, with and without filtering of Galactic emission. As tracers of the LSS, we use the Two Micron All-Sky Survey and the Wide-field InfraRed Explorer redshift catalogues to produce galaxy number density maps. The cross-correlation functions all show peak amplitudes at 0°, decreasing with varying slopes towards zero correlation over a range of 1°. The cross-correlation signals include components from point source, Galactic, and extragalactic diffuse emission. We use models of the diffuse emission from smoothing the density maps with Gaussians of sizes 1-4 Mpc to find limits on the cosmic web components. From these models, we find surface brightness 99.7 per cent upper limits in the range of 0.09-2.20 mJy beam-1 (average beam size of 2.6 arcmin), corresponding to 0.01-0.30 mJy arcmin-2. Assuming equipartition between energy densities of cosmic rays and the magnetic field, the flux density limits translate to magnetic field strength limits of 0.03-1.98 μG, depending heavily on the spectral index. We conclude that for a 3σ detection of 0.1 μG magnetic field strengths via cross-correlations, image depths of sub-mJy to sub-μJy are necessary. We include discussion on the treatment and effect of extragalactic point sources and Galactic emission, and next steps for building on this work.

The Dispersion of Fast Radio Bursts from a Structured Intergalactic Medium at Redshifts z < 1.5

NASA Astrophysics Data System (ADS)

Shull, J. Michael; Danforth, Charles W.

2018-01-01

We analyze the sources of free electrons that produce the large dispersion measures, {DM}≈ 300{--}1600 (in units of cm‑3 pc), observed toward fast radio bursts (FRBs). Individual galaxies typically produce {DM}∼ 25{--}60 {{cm}}-3 {pc} from ionized gas in their disk, disk-halo interface, and circumgalactic medium. Toward an FRB source at redshift z, a homogeneous intergalactic medium (IGM) containing a fraction {f}{IGM} of cosmological baryons will produce {DM}=(935 {{cm}}-3 {pc}){f}{IGM} {h}70-1I(z), where I{(z)=(2/3{{{Ω }}}m)[\\{{{{Ω }}}m(1+z)}3+{{{Ω }}}{{Λ }}\\}{}1/2-1]. A structured IGM of photoionized Lyα absorbers in the cosmic web produces similar dispersion, modeled from the observed distribution, {f}b(N,z), of H I (Lyα-forest) absorbers in column density and redshift with ionization corrections and scaling relations from cosmological simulations. An analytic formula for DM(z) applied to observed FRB dispersions suggests that {z}{FRB}≈ 0.2{--}1.5 for an IGM containing a significant baryon fraction, {f}{IGM}=0.6+/- 0.1. Future surveys of the statistical distribution, DM(z), of FRBs identified with specific galaxies and redshifts can be used to calibrate the IGM baryon fraction and distribution of Lyα absorbers. Fluctuations in DM at the level ±10 cm‑3 pc will arise from filaments and voids in the cosmic web.

OLTARIS: An Efficient Web-Based Tool for Analyzing Materials Exposed to Space Radiation

NASA Technical Reports Server (NTRS)

Slaba, Tony; McMullen, Amelia M.; Thibeault, Sheila A.; Sandridge, Chris A.; Clowdsley, Martha S.; Blatting, Steve R.

2011-01-01

The near-Earth space radiation environment includes energetic galactic cosmic rays (GCR), high intensity proton and electron belts, and the potential for solar particle events (SPE). These sources may penetrate shielding materials and deposit significant energy in sensitive electronic devices on board spacecraft and satellites. Material and design optimization methods may be used to reduce the exposure and extend the operational lifetime of individual components and systems. Since laboratory experiments are expensive and may not cover the range of particles and energies relevant for space applications, such optimization may be done computationally with efficient algorithms that include the various constraints placed on the component, system, or mission. In the present work, the web-based tool OLTARIS (On-Line Tool for the Assessment of Radiation in Space) is presented, and the applicability of the tool for rapidly analyzing exposure levels within either complicated shielding geometries or user-defined material slabs exposed to space radiation is demonstrated. An example approach for material optimization is also presented. Slabs of various advanced multifunctional materials are defined and exposed to several space radiation environments. The materials and thicknesses defining each layer in the slab are then systematically adjusted to arrive at an optimal slab configuration.

The Keck Cosmic Web Imager (KCWI): A Powerful New Integral Field Spectrograph for the Keck Observatory

NASA Astrophysics Data System (ADS)

Morrissey, Patrick; KCWI Team

2013-01-01

The Keck Cosmic Web Imager (KCWI) is a new facility instrument being developed for the W. M. Keck Observatory and funded for construction by the Telescope System Instrumentation Program (TSIP) of the National Science Foundation (NSF). KCWI is a bench-mounted spectrograph for the Keck II right Nasmyth focal station, providing integral field spectroscopy over a seeing-limited field up to 20"x33" in extent. Selectable Volume Phase Holographic (VPH) gratings provide high efficiency and spectral resolution in the range of 1000 to 20000. The dual-beam design of KCWI passed a Preliminary Design Review in summer 2011. The detailed design of the KCWI blue channel (350 to 700 nm) is now nearly complete, with the red channel (530 to 1050 nm) planned for a phased implementation contingent upon additional funding. KCWI builds on the experience of the Caltech team in implementing the Cosmic Web Imager (CWI), in operation since 2009 at Palomar Observatory. KCWI adds considerable flexibility to the CWI design, and will take full advantage of the excellent seeing and dark sky above Mauna Kea with a selectable nod-and-shuffle observing mode. The KCWI team is lead by Caltech (project management, design and implementation) in partnership with the University of California at Santa Cruz (camera optical and mechanical design) and the W. M. Keck Observatory (program oversight and observatory interfaces).

Dark Matter and Cosmic Web Story

NASA Astrophysics Data System (ADS)

Einasto, Jaan

2014-01-01

The development of concepts of dark matter and cosmic web are described as paradigm changes in cosmology. As characteristic in paradigm shifts, there is no single discovery; the new concepts were developed step-by-step by many scientists. The book describes the classical cosmological paradigm, elaborated in the first half of the 20th century. Next the book describes problems in the classical picture, and steps to solve the discrepancies, which eventually led to the formation of the modern cosmological paradigm. The new paradigm tells that the Universe is dominated by dark matter and dark energy, that it has the structure in the form of the cosmic web, and that it has evolved through an inflationary initial stage. The story is told from the perspective of one of the participants of events. The book concentrates to the path of the research, difficulties encountered, and discussions in favour or against new concepts. A special flavour gives to the story the description of difficulties of doing revolutionary research in an occupied country behind the Iron Curtain -- as well as convincing scientists in the West -- and the development of Estonia towards a free country. The book is accompanied by a website (http://www.aai.ee/~einasto/DarkMatter) which contains additional material: copies of originals of some crucial papers, astronomical movies, and also movies which show the private life of the author.

Massive gravity wrapped in the cosmic web

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

Shim, Junsup; Lee, Jounghun; Li, Baojiu, E-mail: jsshim@astro.snu.ac.kr, E-mail: jounghun@astro.snu.ac.kr

We study how the filamentary pattern of the cosmic web changes if the true gravity deviates from general relativity (GR) on a large scale. The f(R) gravity, whose strength is controlled to satisfy the current observational constraints on the cluster scale, is adopted as our fiducial model and a large, high-resolution N-body simulation is utilized for this study. By applying the minimal spanning tree algorithm to the halo catalogs from the simulation at various epochs, we identify the main stems of the rich superclusters located in the most prominent filamentary section of the cosmic web and determine their spatial extentsmore » per member cluster to be the degree of their straightness. It is found that the f(R) gravity has the effect of significantly bending the superclusters and that the effect becomes stronger as the universe evolves. Even in the case where the deviation from GR is too small to be detectable by any other observables, the degree of the supercluster straightness exhibits a conspicuous difference between the f(R) and the GR models. Our results also imply that the supercluster straightness could be a useful discriminator of f(R) gravity from the coupled dark energy since it is shown to evolve differently between the two models. As a final conclusion, the degree of the straightness of the rich superclusters should provide a powerful cosmological test of large scale gravity.« less

A NEWLY FORMING COLD FLOW PROTOGALACTIC DISK, A SIGNATURE OF COLD ACCRETION FROM THE COSMIC WEB

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

Martin, D. Christopher; Matuszewski, Mateusz; Morrissey, Patrick

How galaxies form from, and are fueled by, gas from the intergalactic medium (IGM) remains one of the major unsolved problems in galaxy formation. While the classical Cold Dark Matter paradigm posits galaxies forming from cooling virialized gas, recent theory and numerical simulations have highlighted the importance of cold accretion flows—relatively cool ( T ∼ few × 104 K) unshocked gas streaming along filaments into dark matter halos, including hot, massive, high-redshift halos. These flows are thought to deposit gas and angular momentum into the circumgalactic medium resulting in disk- or ring-like structures, eventually coalescing into galaxies forming at filamentarymore » intersections. We earlier reported a bright, Ly α emitting filament near the QSO HS1549+19 at redshift z = 2.843 discovered with the Palomar Cosmic Web Imager. We now report that the bright part of this filament is an enormous ( R > 100 kpc) rotating structure of hydrogen gas with a disk-like velocity profile consistent with a 4 × 10{sup 12} M {sub ⊙} halo. The orbital time of the outer part of the what we term a “protodisk” is comparable to the virialization time and the age of the universe at this redshift. We propose that this protodisk can only have recently formed from cold gas flowing directly from the cosmic web.« less

A new probe of the magnetic field power spectrum in cosmic web filaments

NASA Astrophysics Data System (ADS)

Hales, Christopher A.; Greiner, Maksim; Ensslin, Torsten A.

2015-08-01

Establishing the properties of magnetic fields on scales larger than galaxy clusters is critical for resolving the unknown origin and evolution of galactic and cluster magnetism. More generally, observations of magnetic fields on cosmic scales are needed for assessing the impacts of magnetism on cosmology, particle physics, and structure formation over the full history of the Universe. However, firm observational evidence for magnetic fields in large scale structure remains elusive. In an effort to address this problem, we have developed a novel statistical method to infer the magnetic field power spectrum in cosmic web filaments using observation of the two-point correlation of Faraday rotation measures from a dense grid of extragalactic radio sources. Here we describe our approach, which embeds and extends the pioneering work of Kolatt (1998) within the context of Information Field Theory (a statistical theory for Bayesian inference on spatially distributed signals; Enfllin et al., 2009). We describe prospects for observation, for example with forthcoming data from the ultra-deep JVLA CHILES Con Pol survey and future surveys with the SKA.

VAO Tools Enhance CANDELS Research Productivity

NASA Astrophysics Data System (ADS)

Greene, Gretchen; Donley, J.; Rodney, S.; LAZIO, J.; Koekemoer, A. M.; Busko, I.; Hanisch, R. J.; VAO Team; CANDELS Team

2013-01-01

The formation of galaxies and their co-evolution with black holes through cosmic time are prominent areas in current extragalactic astronomy. New methods in science research are building upon collaborations between scientists and archive data centers which span large volumes of multi-wavelength and heterogeneous data. A successful example of this form of teamwork is demonstrated by the CANDELS (Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey) and the Virtual Astronomical Observatory (VAO) collaboration. The CANDELS project archive data provider services are registered and discoverable in the VAO through an innovative web based Data Discovery Tool, providing a drill down capability and cross-referencing with other co-spatially located astronomical catalogs, images and spectra. The CANDELS team is working together with the VAO to define new methods for analyzing Spectral Energy Distributions of galaxies containing active galactic nuclei, and helping to evolve advanced catalog matching methods for exploring images of variable depths, wavelengths and resolution. Through the publication of VOEvents, the CANDELS project is publishing data streams for newly discovered supernovae that are bright enough to be followed from the ground.

ELUCID - Exploring the Local Universe with ReConstructed Initial Density Field III: Constrained Simulation in the SDSS Volume

NASA Astrophysics Data System (ADS)

Wang, Huiyuan; Mo, H. J.; Yang, Xiaohu; Zhang, Youcai; Shi, JingJing; Jing, Y. P.; Liu, Chengze; Li, Shijie; Kang, Xi; Gao, Yang

2016-11-01

A method we developed recently for the reconstruction of the initial density field in the nearby universe is applied to the Sloan Digital Sky Survey Data Release 7. A high-resolution N-body constrained simulation (CS) of the reconstructed initial conditions, with 30723 particles evolved in a 500 {h}-1 {Mpc} box, is carried out and analyzed in terms of the statistical properties of the final density field and its relation with the distribution of Sloan Digital Sky Survey galaxies. We find that the statistical properties of the cosmic web and the halo populations are accurately reproduced in the CS. The galaxy density field is strongly correlated with the CS density field, with a bias that depends on both galaxy luminosity and color. Our further investigations show that the CS provides robust quantities describing the environments within which the observed galaxies and galaxy systems reside. Cosmic variance is greatly reduced in the CS so that the statistical uncertainties can be controlled effectively, even for samples of small volumes.

Multi-stream portrait of the Cosmic web

NASA Astrophysics Data System (ADS)

Ramachandra, Nesar; Shandarin, Sergei

2016-03-01

We report the results of the first study of the multi-stream environment of dark matter haloes in cosmological N-body simulations in the ΛCDM cosmology. The full dynamical state of dark matter can be described as a three-dimensional sub-manifold in six-dimensional phase space - the dark matter sheet. In our study we use a Lagrangian sub-manifold x = x (q , t) (where x and q are co-moving Eulerian and Lagrangian coordinates respectively), which is dynamically equivalent to the dark matter sheet but is more convenient for numerical analysis. Our major results can be summarized as follows. At the resolution of the simulation, the cosmic web represents a hierarchical structure: each halo is embedded in the filamentary framework of the web predominantly at the filament crossings, and each filament is embedded in the wall like fabric of the web at the wall crossings. Locally, each halo or sub-halo is a peak in the number of streams field. The number of streams in the neighbouring filaments is higher than in the neighbouring walls. The walls are regions where number of streams is equal to three or a few. Voids are uniquely defined by the local condition requiring to be a single-stream flow region.

Cosmic web type dependence of halo clustering

NASA Astrophysics Data System (ADS)

Fisher, J. D.; Faltenbacher, A.

2018-01-01

We use the Millennium Simulation to show that halo clustering varies significantly with cosmic web type. Haloes are classified as node, filament, sheet and void haloes based on the eigenvalue decomposition of the velocity shear tensor. The velocity field is sampled by the peculiar velocities of a fixed number of neighbouring haloes, and spatial derivatives are computed using a kernel borrowed from smoothed particle hydrodynamics. The classification scheme is used to examine the clustering of haloes as a function of web type for haloes with masses larger than 1011 h- 1 M⊙. We find that node haloes show positive bias, filament haloes show negligible bias and void and sheet haloes are antibiased independent of halo mass. Our findings suggest that the mass dependence of halo clustering is rooted in the composition of web types as a function of halo mass. The substantial fraction of node-type haloes for halo masses ≳ 2 × 1013 h- 1 M⊙ leads to positive bias. Filament-type haloes prevail at intermediate masses, 1012-1013 h- 1 M⊙, resulting in unbiased clustering. The large contribution of sheet-type haloes at low halo masses ≲ 1012 h- 1 M⊙ generates antibiasing.

The cosmic web in CosmoGrid void regions

NASA Astrophysics Data System (ADS)

Rieder, Steven; van de Weygaert, Rien; Cautun, Marius; Beygu, Burcu; Portegies Zwart, Simon

2016-10-01

We study the formation and evolution of the cosmic web, using the high-resolution CosmoGrid ΛCDM simulation. In particular, we investigate the evolution of the large-scale structure around void halo groups, and compare this to observations of the VGS-31 galaxy group, which consists of three interacting galaxies inside a large void. The structure around such haloes shows a great deal of tenuous structure, with most of such systems being embedded in intra-void filaments and walls. We use the Nexus+} algorithm to detect walls and filaments in CosmoGrid, and find them to be present and detectable at every scale. The void regions embed tenuous walls, which in turn embed tenuous filaments. We hypothesize that the void galaxy group of VGS-31 formed in such an environment.

Caustic Skeleton & Cosmic Web

NASA Astrophysics Data System (ADS)

Feldbrugge, Job; van de Weygaert, Rien; Hidding, Johan; Feldbrugge, Joost

2018-05-01

We present a general formalism for identifying the caustic structure of a dynamically evolving mass distribution, in an arbitrary dimensional space. The identification of caustics in fluids with Hamiltonian dynamics, viewed in Lagrangian space, corresponds to the classification of singularities in Lagrangian catastrophe theory. On the basis of this formalism we develop a theoretical framework for the dynamics of the formation of the cosmic web, and specifically those aspects that characterize its unique nature: its complex topological connectivity and multiscale spinal structure of sheetlike membranes, elongated filaments and compact cluster nodes. Given the collisionless nature of the gravitationally dominant dark matter component in the universe, the presented formalism entails an accurate description of the spatial organization of matter resulting from the gravitationally driven formation of cosmic structure. The present work represents a significant extension of the work by Arnol'd et al. [1], who classified the caustics that develop in one- and two-dimensional systems that evolve according to the Zel'dovich approximation. His seminal work established the defining role of emerging singularities in the formation of nonlinear structures in the universe. At the transition from the linear to nonlinear structure evolution, the first complex features emerge at locations where different fluid elements cross to establish multistream regions. Involving a complex folding of the 6-D sheetlike phase-space distribution, it manifests itself in the appearance of infinite density caustic features. The classification and characterization of these mass element foldings can be encapsulated in caustic conditions on the eigenvalue and eigenvector fields of the deformation tensor field. In this study we introduce an alternative and transparent proof for Lagrangian catastrophe theory. This facilitates the derivation of the caustic conditions for general Lagrangian fluids, with arbitrary dynamics. Most important in the present context is that it allows us to follow and describe the full three-dimensional geometric and topological complexity of the purely gravitationally evolving nonlinear cosmic matter field. While generic and statistical results can be based on the eigenvalue characteristics, one of our key findings is that of the significance of the eigenvector field of the deformation field for outlining the entire spatial structure of the caustic skeleton emerging from a primordial density field. In this paper we explicitly consider the caustic conditions for the three-dimensional Zel'dovich approximation, extending earlier work on those for one- and two-dimensional fluids towards the full spatial richness of the cosmic web. In an accompanying publication, we apply this towards a full three-dimensional study of caustics in the formation of the cosmic web and evaluate in how far it manages to outline and identify the intricate skeletal features in the corresponding N-body simulations.

A machine learning approach to galaxy-LSS classification - I. Imprints on halo merger trees

NASA Astrophysics Data System (ADS)

Hui, Jianan; Aragon, Miguel; Cui, Xinping; Flegal, James M.

2018-04-01

The cosmic web plays a major role in the formation and evolution of galaxies and defines, to a large extent, their properties. However, the relation between galaxies and environment is still not well understood. Here, we present a machine learning approach to study imprints of environmental effects on the mass assembly of haloes. We present a galaxy-LSS machine learning classifier based on galaxy properties sensitive to the environment. We then use the classifier to assess the relevance of each property. Correlations between galaxy properties and their cosmic environment can be used to predict galaxy membership to void/wall or filament/cluster with an accuracy of 93 per cent. Our study unveils environmental information encoded in properties of haloes not normally considered directly dependent on the cosmic environment such as merger history and complexity. Understanding the physical mechanism by which the cosmic web is imprinted in a halo can lead to significant improvements in galaxy formation models. This is accomplished by extracting features from galaxy properties and merger trees, computing feature scores for each feature and then applying support vector machine (SVM) to different feature sets. To this end, we have discovered that the shape and depth of the merger tree, formation time, and density of the galaxy are strongly associated with the cosmic environment. We describe a significant improvement in the original classification algorithm by performing LU decomposition of the distance matrix computed by the feature vectors and then using the output of the decomposition as input vectors for SVM.

Propagation of cosmic rays in the galaxy

NASA Technical Reports Server (NTRS)

Daniel, R. R.; Stephens, S. A.

1974-01-01

The characteristics of a model for analyzing the propagation of cosmic rays are discussed. The requirements for analyzing the relevant observational data on cosmic rays are defines as: (1) the chemical and isotopic composition of cosmic rays as a function of energy, (2) the flux and energy spectrum of the individual nucleonic components, (3) the flux and energy spectrum of the electronic component, (4) the cosmic ray prehistory, and (5) the degree of isotropy in their arrival directions as a function of energy. It is stated that the model which has been able to bring to pass the greatest measure of success is the galactic confinement model.

Cosmic Dawn Science Interest Group

NASA Astrophysics Data System (ADS)

Lazio, T. Joseph W.; Cosmic Origins Program Analysis Group

2016-01-01

Cosmic Dawn was identified as one of the three science objectives for this decade in the _New Worlds, New Horizons_ Decadal report, and it will likely continue to be a research focus well into the next decade. Cosmic Dawn refers to the interval during which the Universe transitioned from a nearly completely neutral state back to a nearly fully ionized state and includes the time during which the first stars formed and the first galaxies assembled.The Cosmic Dawn Science Interest Group (SIG) was formed recently under the auspices of the Cosmic Origins Program Analysis Group (COPAG). The Cosmic Dawn SIG focusses on the science cases, observations, and technology development needed to address the "great mystery" of Cosmic Origins. The reach of this SIG is broad, involving the nature of the first stars and the detectability of gamma-ray bursts at high redshifts, the extent to which the first galaxies and first supermassive black holes grew together, and the technology required to pursue these questions.For further information, consult the Cosmic Dawn SIG Web site http://cd-sig.jpl.nasa.gov/ and join the mailing list (by contacting the author).Part of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

Mapping Dark Matter in Simulated Galaxy Clusters

NASA Astrophysics Data System (ADS)

Bowyer, Rachel

2018-01-01

Galaxy clusters are the most massive bound objects in the Universe with most of their mass being dark matter. Cosmological simulations of structure formation show that clusters are embedded in a cosmic web of dark matter filaments and large scale structure. It is thought that these filaments are found preferentially close to the long axes of clusters. We extract galaxy clusters from the simulations "cosmo-OWLS" in order to study their properties directly and also to infer their properties from weak gravitational lensing signatures. We investigate various stacking procedures to enhance the signal of the filaments and large scale structure surrounding the clusters to better understand how the filaments of the cosmic web connect with galaxy clusters. This project was supported in part by the NSF REU grant AST-1358980 and by the Nantucket Maria Mitchell Association.

How does the cosmic web impact assembly bias?

NASA Astrophysics Data System (ADS)

Musso, M.; Cadiou, C.; Pichon, C.; Codis, S.; Kraljic, K.; Dubois, Y.

2018-06-01

The mass, accretion rate, and formation time of dark matter haloes near protofilaments (identified as saddle points of the potential) are analytically predicted using a conditional version of the excursion set approach in its so-called upcrossing approximation. The model predicts that at fixed mass, mass accretion rate and formation time vary with orientation and distance from the saddle, demonstrating that assembly bias is indeed influenced by the tides imposed by the cosmic web. Starved, early-forming haloes of smaller mass lie preferentially along the main axis of filaments, while more massive and younger haloes are found closer to the nodes. Distinct gradients for distinct tracers such as typical mass and accretion rate occur because the saddle condition is anisotropic, and because the statistics of these observables depend on both the conditional means and their covariances. The theory is extended to other critical points of the potential field. The response of the mass function to variations of the matter density field (the so-called large-scale bias) is computed, and its trend with accretion rate is shown to invert along the filament. The signature of this model should correspond at low redshift to an excess of reddened galactic hosts at fixed mass along preferred directions, as recently reported in spectroscopic and photometric surveys and in hydrodynamical simulations. The anisotropy of the cosmic web emerges therefore as a significant ingredient to describe jointly the dynamics and physics of galaxies, e.g. in the context of intrinsic alignments or morphological diversity.

Clusters, voids and reconstructions of the cosmic web

NASA Astrophysics Data System (ADS)

Bos, E. G. Patrick

2016-12-01

The Universe is filled for 95% with dark matter and energy that we cannot see. Of the remaining 5% normal matter we can only see a small part. However, if we want to study the Universe as a whole, we will have to get to know it for 100%. We have to uncover indirectly where dark matter is hiding and what is the nature of dark energy. In this thesis we explore two such methods. The first part describes how we can use the large empty regions between galaxies, "voids", to learn more about dark energy. We converted our theoretical simulations to a model of real observations of galaxies. In this model, we perform the same measurements as we would in real observations. This way, we show that it is indeed possible to unravel the nature of dark energy. The second part is based on our computer code: BARCODE. It unites two models: a physical model of the formation of the Cosmic Web, and a description of the observational effects of (clusters of) galaxies, in particular the effect of redshift on distance measurements. It allows us to back-trace our observations to the primordial conditions. These enable us to trace all (dark) matter, also that which we did not directly observe. The result is a reconstruction of the complete Cosmic Web. In these, we studied "filaments". These objects have not yet been extensively studied. BARCODE will enable further study, e.g. by using it to find observable filaments.

The origin of cosmic rays

NASA Technical Reports Server (NTRS)

Eichler, D.

1986-01-01

Data related to the development of cosmic rays are discussed. The relationship between cosmic ray production and the steady-state Boltzmann equation is analyzed. The importance of the power-law spectrum, the scattering rate, the theory of shock acceleration, anisotropic instabilities, and cosmic ray diffusion in the formation of cosmic rays is described. It is noted that spacecraft observations at the earth's bow shock are useful for studying cosmic rays and that the data support the collisionless shock-wave theory of cosmic ray origin.

Void asymmetries in the cosmic web: a mechanism for bulk flows

NASA Astrophysics Data System (ADS)

Bland-Hawthorn, J.; Sharma, S.

2016-10-01

Bulk flows of galaxies moving with respect to the cosmic microwave background are well established observationally and seen in the most recent ΛCDM simulations. With the aid of an idealised Gadget-2 simulation, we show that void asymmetries in the cosmic web can exacerbate local bulk flows of galaxies. The {\\it Cosmicflows-2} survey, which has mapped in detail the 3D structure of the Local Universe, reveals that the Local Group resides in a ``local sheet'' of galaxies that borders a ``local void'' with a diameter of about 40 Mpc. The void is emptying out at a rate of 16 km s-1 Mpc-1. In a co-moving frame, the Local Sheet is found to be moving away from the Local Void at ~ 260 km s-1. Our model shows how asymmetric collapse due to unbalanced voids on either side of a developing sheet or wall can lead to a systematic movement of the sheet. We conjectured that asymmetries could lead to a large-scale separation of dark matter and baryons, thereby driving a dependence of galaxy properties with environment, but we do {\\it not} find any evidence for this effect.

Is the universe a sponge?

NASA Astrophysics Data System (ADS)

Bucher, Martin

2016-11-01

Does the large-scale universe look more like meatballs, like Swiss cheese or like a sponge? The differences between these types of universe are described in J Richard Gott's The Cosmic Web: Mysterious Architecture of the Universe.

WWW.NMDB.EU: The real-time Neutron Monitor database

NASA Astrophysics Data System (ADS)

Klein, Karl-Ludwig; Steigies, Christian T.; NMDB Consortium

2010-05-01

The Real time database for high-resolution neutron monitor measurements (NMDB), which was supported by the 7th framework program of the European Commission, hosts data on cosmic rays in the GeV range from European and some non-European neutron monitor stations. It offers a variety of applications ranging from the representation and retrieval of cosmic ray data over solar energetic particle alerts to the calculation of ionisation doses in the atmosphere and radiation dose rates at aircraft altitudes. Furthermore the web site comprises public outreach pages in several languages and offers training material on cosmic rays for university students and researchers and engineers who want to get familiar with cosmic rays and neutron monitor measurements. This contribution presents an overview of the provided services and indications on how to access the database. Operators of other neutron monitor stations are welcome to submit their data to NMDB.

Seeing the invisible

NASA Astrophysics Data System (ADS)

Heymans, Catherine

2014-07-01

Light from distant galaxies is distorted on its journey to us via a vast network of dark matter. By observing this phenomenon, known as gravitational lensing, physicists are able to map the structure of this dark cosmic web, as Catherine Heymans explains.

Reviews Book: George's Cosmic Treasure Hunt Book: 50 Physics Ideas You Really Need to Know Book: Head First Physics Book: Force and Motion—An illustrated Guide to Newton's Laws Book: Froth! The Science of Beer Equipment: SEP Charge Indicator Book: How Mathematics Happened—The First 50,000 Years Web Watch

NASA Astrophysics Data System (ADS)

2009-11-01

WE RECOMMEND George's Cosmic Treasure Hunt Another science-based kids' adventure from the Hawkings 50 Physics Ideas You Really Need to Know Brief, accessible descriptions of some complex physics Head First Physics Mechanics-focused non-traditional textbook Force and Motion—An illustrated Guide to Newton's Laws An original text aimed at students Froth! The Science of Beer A tongue-in-cheek physics-heavy guide to brewery science SEP Charge Indicator Classroom equipment that is affordable, usable and works How Mathematics Happened—The First 50,000 Years An enjoyable read suitable for student or teacher WEB WATCH Simulators can be useful teaching aids, as long as you remain aware of their flaws

Probing Gas Stripping with Resolved Star-Formation Maps of Virgo Filament Galaxies

NASA Astrophysics Data System (ADS)

Collova, Natasha

2018-01-01

We are conducting a multi-wavelength study of the gas in galaxies at a variety of positions in the cosmic web surrounding the Virgo cluster, one of the best studied regions of high density in the Universe. Galaxies are very likely pre-processed in filaments before falling into clusters, and our goal is to understand how galaxies are altered as they move through the cosmic web and enter the densest regions. We present spatially-resolved H-alpha imaging results from the KPNO 0.9-m and INT 2.54-m telescopes for a preliminary sample of 30 galaxies. We will combine the star-formation maps with observations of molecular and atomic gas to calculate gas consumption timescales, characterize multiple phases of the galactic gas, and look for signatures of environmentally-driven depletion. This work is supported in part by NSF grant AST-1716657.

Why do galactic spins flip in the cosmic web? A Theory of Tidal Torques near saddles

NASA Astrophysics Data System (ADS)

Pichon, Christophe; Codis, Sandrine; Pogosyan, Dmitry; Dubois, Yohan; Desjacques, Vincent; Devriendt, Julien

2016-10-01

Filaments of the cosmic web drive spin acquisition of disc galaxies. The point process of filament-type saddle represent best this environment and can be used to revisit the Tidal Torque Theory in the context of an anisotropic peak (saddle) background split. The constrained misalignment between the tidal tensor and the Hessian of the density field generated in the vicinity of filament saddle points simply explains the corresponding transverse and longitudinal point-reflection symmetric geometry of spin distribution. It predicts in particular an azimuthal orientation of the spins of more massive galaxies and spin alignment with the filament for less massive galaxies. Its scale dependence also allows us to relate the transition mass corresponding to the alignment of dark matter halos' spin relative to the direction of their neighboring filament to this geometry, and to predict accordingly it's scaling with the mass of non linearity, as was measured in simulations.

The magnetic field and turbulence of the cosmic web measured using a brilliant fast radio burst.

PubMed

Ravi, V; Shannon, R M; Bailes, M; Bannister, K; Bhandari, S; Bhat, N D R; Burke-Spolaor, S; Caleb, M; Flynn, C; Jameson, A; Johnston, S; Keane, E F; Kerr, M; Tiburzi, C; Tuntsov, A V; Vedantham, H K

2016-12-09

Fast radio bursts (FRBs) are millisecond-duration events thought to originate beyond the Milky Way galaxy. Uncertainty surrounding the burst sources, and their propagation through intervening plasma, has limited their use as cosmological probes. We report on a mildly dispersed (dispersion measure 266.5 ± 0.1 parsecs per cubic centimeter), exceptionally intense (120 ± 30 janskys), linearly polarized, scintillating burst (FRB 150807) that we directly localize to 9 square arc minutes. On the basis of a low Faraday rotation (12.0 ± 0.7 radians per square meter), we infer negligible magnetization in the circum-burst plasma and constrain the net magnetization of the cosmic web along this sightline to <21 nanogauss, parallel to the line-of-sight. The burst scintillation suggests weak turbulence in the ionized intergalactic medium. Copyright © 2016, American Association for the Advancement of Science.

Xenia: A Probe of Cosmic Chemical Evolution

NASA Technical Reports Server (NTRS)

Kouveliotou, Chryssa; Piro, L.

2008-01-01

Xenia is a concept study for a medium-size astrophysical cosmology mission addressing the Cosmic Origins key objective of NASA's Science Plan. The fundamental goal of this objective is to understand the formation and evolution of structures on various scales from the early Universe to the present time (stars, galaxies and the cosmic web). Xenia will use X-and y-ray monitoring and wide field X-ray imaging and high-resolution spectroscopy to collect essential information from three major tracers of these cosmic structures: the Warm Hot Intergalactic Medium (WHIM), Galaxy Clusters and Gamma Ray Bursts (GRBs). Our goal is to trace the chemo-dynamical history of the ubiquitous warm hot diffuse baryon component in the Universe residing in cosmic filaments and clusters of galaxies up to its formation epoch (at z =0-2) and to map star formation and galaxy metal enrichment into the re-ionization era beyond z 6. The concept of Xenia (Greek for "hospitality") evolved in parallel with the Explorer of Diffuse Emission and GRB Explosions (EDGE), a mission proposed by a multinational collaboration to the ESA Cosmic Vision 2015. Xenia incorporates the European and Japanese collaborators into a U.S. led mission that builds on the scientific objectives and technological readiness of EDGE.

Xenia: A Probe of Cosmic Chemical Evolution

NASA Astrophysics Data System (ADS)

Kouveliotou, Chryssa; Piro, L.; Xenia Collaboration

2008-03-01

Xenia is a concept study for a medium-size astrophysical cosmology mission addressing the Cosmic Origins key objective of NASA's Science Plan. The fundamental goal of this objective is to understand the formation and evolution of structures on various scales from the early Universe to the present time (stars, galaxies and the cosmic web). Xenia will use X-and γ-ray monitoring and wide field X-ray imaging and high-resolution spectroscopy to collect essential information from three major tracers of these cosmic structures: the Warm Hot Intergalactic Medium (WHIM), Galaxy Clusters and Gamma Ray Bursts (GRBs). Our goal is to trace the chemo-dynamical history of the ubiquitous warm hot diffuse baryon component in the Universe residing in cosmic filaments and clusters of galaxies up to its formation epoch (at z =0-2) and to map star formation and galaxy metal enrichment into the re-ionization era beyond z 6. The concept of Xenia (Greek for "hospitality") evolved in parallel with the Explorer of Diffuse Emission and GRB Explosions (EDGE), a mission proposed by a multinational collaboration to the ESA Cosmic Vision 2015. Xenia incorporates the European and Japanese collaborators into a U.S. led mission that builds on the scientific objectives and technological readiness of EDGE.

Galaxy evolution in the metric of the cosmic web

NASA Astrophysics Data System (ADS)

Kraljic, K.; Arnouts, S.; Pichon, C.; Laigle, C.; de la Torre, S.; Vibert, D.; Cadiou, C.; Dubois, Y.; Treyer, M.; Schimd, C.; Codis, S.; de Lapparent, V.; Devriendt, J.; Hwang, H. S.; Le Borgne, D.; Malavasi, N.; Milliard, B.; Musso, M.; Pogosyan, D.; Alpaslan, M.; Bland-Hawthorn, J.; Wright, A. H.

2018-02-01

The role of the cosmic web in shaping galaxy properties is investigated in the Galaxy And Mass Assembly (GAMA) spectroscopic survey in the redshift range 0.03 ≤ z ≤ 0.25. The stellar mass, u - r dust corrected colour and specific star formation rate (sSFR) of galaxies are analysed as a function of their distances to the 3D cosmic web features, such as nodes, filaments and walls, as reconstructed by DisPerSE. Significant mass and type/colour gradients are found for the whole population, with more massive and/or passive galaxies being located closer to the filament and wall than their less massive and/or star-forming counterparts. Mass segregation persists among the star-forming population alone. The red fraction of galaxies increases when closing in on nodes, and on filaments regardless of the distance to nodes. Similarly, the star-forming population reddens (or lowers its sSFR) at fixed mass when closing in on filament, implying that some quenching takes place. These trends are also found in the state-of-the-art hydrodynamical simulation HORIZON-AGN. These results suggest that on top of stellar mass and large-scale density, the traceless component of the tides from the anisotropic large-scale environment also shapes galactic properties. An extension of excursion theory accounting for filamentary tides provides a qualitative explanation in terms of anisotropic assembly bias: at a given mass, the accretion rate varies with the orientation and distance to filaments. It also explains the absence of type/colour gradients in the data on smaller, non-linear scales.

Observing Interstellar and Intergalactic Magnetic Fields

NASA Astrophysics Data System (ADS)

Han, J. L.

2017-08-01

Observational results of interstellar and intergalactic magnetic fields are reviewed, including the fields in supernova remnants and loops, interstellar filaments and clouds, Hii regions and bubbles, the Milky Way and nearby galaxies, galaxy clusters, and the cosmic web. A variety of approaches are used to investigate these fields. The orientations of magnetic fields in interstellar filaments and molecular clouds are traced by polarized thermal dust emission and starlight polarization. The field strengths and directions along the line of sight in dense clouds and cores are measured by Zeeman splitting of emission or absorption lines. The large-scale magnetic fields in the Milky Way have been best probed by Faraday rotation measures of a large number of pulsars and extragalactic radio sources. The coherent Galactic magnetic fields are found to follow the spiral arms and have their direction reversals in arms and interarm regions in the disk. The azimuthal fields in the halo reverse their directions below and above the Galactic plane. The orientations of organized magnetic fields in nearby galaxies have been observed through polarized synchrotron emission. Magnetic fields in the intracluster medium have been indicated by diffuse radio halos, polarized radio relics, and Faraday rotations of embedded radio galaxies and background sources. Sparse evidence for very weak magnetic fields in the cosmic web is the detection of the faint radio bridge between the Coma cluster and A1367. Future observations should aim at the 3D tomography of the large-scale coherent magnetic fields in our Galaxy and nearby galaxies, a better description of intracluster field properties, and firm detections of intergalactic magnetic fields in the cosmic web.

Blue camera of the Keck cosmic web imager, fabrication and testing

NASA Astrophysics Data System (ADS)

Rockosi, Constance; Cowley, David; Cabak, Jerry; Hilyard, David; Pfister, Terry

2016-08-01

The Keck Cosmic Web Imager (KCWI) is a new facility instrument being developed for the W. M. Keck Observatory and funded for construction by the Telescope System Instrumentation Program (TSIP) of the National Science Foundation (NSF). KCWI is a bench-mounted spectrograph for the Keck II right Nasmyth focal station, providing integral field spectroscopy over a seeing-limited field up to 20" x 33" in extent. Selectable Volume Phase Holographic (VPH) gratings provide high efficiency and spectral resolution in the range of 1000 to 20000. The dual-beam design of KCWI passed a Preliminary Design Review in summer 2011. The detailed design of the KCWI blue channel (350 to 700 nm) is now nearly complete, with the red channel (530 to 1050 nm) planned for a phased implementation contingent upon additional funding. KCWI builds on the experience of the Caltech team in implementing the Cosmic Web Imager (CWI), in operation since 2009 at Palomar Observatory. KCWI adds considerable flexibility to the CWI design, and will take full advantage of the excellent seeing and dark sky above Mauna Kea with a selectable nod-and-shuffle observing mode. In this paper, models of the expected KCWI sensitivity and background subtraction capability are presented, along with a detailed description of the instrument design. The KCWI team is lead by Caltech (project management, design and implementation) in partnership with the University of California at Santa Cruz (camera optical and mechanical design) and the W. M. Keck Observatory (program oversight and observatory interfaces). The optical design of the blue camera for the Keck Cosmic Web Imager (KCWI) by Harland Epps of the University of California, Santa Cruz is a lens assembly consisting of eight spherical optical elements. Half the elements are calcium fluoride and all elements are air spaced. The design of the camera barrel is unique in that all the optics are secured in their respective cells with an RTV annulus without additional hardware such as retaining rings. The optical design and the robust lens mounting concept has allowed UCO/Lick to design a straightforward lens camera assembly. However, alignment sensitivity is a strict 15 μm for most elements. This drives the fabrication, assembly, and performance of the camera barrel.

Charge 4/3 leptons in cosmic rays

NASA Technical Reports Server (NTRS)

Wada, T.; Yamashita, Y.; Imaeda, K.; Yamamoto, I.

1985-01-01

A cosmic ray counter telescope has been operated at zenith angles of 0, 40, 44, and 60 degs in order to look for charge 4/3 particles. A few million clean single cosmic rays of each zenith angle are analyzed.

Formation of Cosmic Carbon Dust Analogues in Plasma Reactors

NASA Technical Reports Server (NTRS)

Salama, Farid

2016-01-01

Cosmic carbon dust analogs are produced, processed and analyzed in the laboratory using NASA's COSmIC (COSmIC Simulation Chamber) Facility. These experiments can be used to derive information on the most efficient molecular precursors in the chemical pathways that eventually lead to the formation of carbonaceous grains in the stellar envelopes of carbon stars.

Pixelsex or Cosmic Revelation – how art & science can meet in public space

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

Otto Roth, Tim

2009-10-28

Tim Otto Roth is known for his large projects in public space linking art & science. In his presentation the German artist and media theorist demonstrates some of his latest projects - among others Cosmic Revelation which changed the KASCADE detector field for cosmic rays at the Karlsruhe Institute of Technology into a giant flashing light field. The Pixelsex project leads him to the question if the universe might be digital. In occasion of his one week residency at CERN Tim Otto Roth explores the material culture of particle physics and its ways of finding pictorial representations. Above all hemore » is interested in methods like the Monte Carlo simulation, but also in CERN as giant collaborative institution and consequently as birthplace for the World Wide Web.« less

Pixelsex or Cosmic Revelation – how art & science can meet in public space

ScienceCinema

Otto Roth, Tim

2018-05-18

Tim Otto Roth is known for his large projects in public space linking art & science. In his presentation the German artist and media theorist demonstrates some of his latest projects - among others Cosmic Revelation which changed the KASCADE detector field for cosmic rays at the Karlsruhe Institute of Technology into a giant flashing light field. The Pixelsex project leads him to the question if the universe might be digital. In occasion of his one week residency at CERN Tim Otto Roth explores the material culture of particle physics and its ways of finding pictorial representations. Above all he is interested in methods like the Monte Carlo simulation, but also in CERN as giant collaborative institution and consequently as birthplace for the World Wide Web.

The part and the whole: voids, supervoids, and their ISW imprint

NASA Astrophysics Data System (ADS)

Kovács, András

2018-04-01

The integrated Sachs-Wolfe (ISW) imprint of extreme structures in the cosmic web probes the dynamical nature of dark energy. Looking through typical cosmic voids, no anomalous signal has been reported. On the contrary, supervoids, associated with large-scale fluctuations in the gravitational potential, have shown potentially disturbing excess signals. In this study, we used the Jubilee ISW simulation to demonstrate how the stacked signal depends on the void definition. We found that large underdensities, with at least ≈5 merged sub-voids, show a peculiar ISW imprint shape with central cold spots and surrounding hot rings, offering a natural way to define supervoids in the cosmic web. We then inspected the real-world Baryon Oscillations Spectroscopic Survey data release 12 (BOSS DR12) data using the simulated imprints as templates. The imprinted profile of BOSS supervoids appears to be more compact than in simulations, requiring an extra α ≈ 0.7 re-scaling of filter sizes. The data reveal an excess ISW-like signal with AISW ≈ 9 amplitude at the ≈2.5σ significance level, unlike previous studies that used isolated voids and reported good consistency with AISW = 1. The tension with the Jubilee-based Λ cold dark matter predictions is ≳2σ, in consistency with independent analyses of supervoids in Dark Energy Survey data. We show that such a very large enhancement of the AISW parameter hints at a possible causal relation between the cosmic microwave background Cold Spot and the Eridanus supervoid. The origin of these findings remains unclear.

WWW.NMDB.EU: The real-time Neutron Monitor databas

NASA Astrophysics Data System (ADS)

Klein, Karl-Ludwig; Steigies, Christian; Steigies, Christian T.; Wimmer-Schweingruber, Robert F.; Kudela, Karel; Strharsky, Igor; Langer, Ronald; Usoskin, Ilya; Ibragimov, Askar; Flückiger, Erwin O.; Bütikofer, Rolf; Eroshenko, Eugenia; Belov, Anatoly; Yanke, Victor; Klein, Karl-Ludwig; Fuller, Nicolas; Mavromichalaki, Helen; Papaioannou, Athana-Sios; Sarlanis, Christos; Souvatzoglou, George; Plainaki, Christina; Geron-Tidou, Maria; Papailiou, Maria-Christina; Mariatos, George; Chilingaryan, Ashot; Hovsepyan, G.; Reymers, Artur; Parisi, Mario; Kryakunova, Olga; Tsepakina, Irina; Nikolayevskiy, Nikolay; Dor-Man, Lev; Pustil'Nik, Lev; García-Población, Oscar

The Real time database for high-resolution neutron monitor measurements(NMDB), which was supported by the 7th Framework Programme of the European Commission, hosts data on cosmic rays in the GeV range from European and some non-European neutron monitor stations. Besides real-time data and historical data over several decades in a unified format, it offers data products such as galactic cosmic ray spectra and applications including solar energetic particle alerts and the calculation of ionisation rates in the atmosphere and effective radiation dose rates at aircraft altitudes. Furthermore the web site comprises public outreach pages in several languages and offers training material on cosmic rays for university students and researchers and engineers who want to become familiar with cosmic rays and neutron monitor measurements. This contribution presents an overview of the provided services and indications on how to access the database. Operators of other neutron monitor stations are welcome to submit their data to NMDB.

The ISB Cancer Genomics Cloud: A Flexible Cloud-Based Platform for Cancer Genomics Research.

PubMed

Reynolds, Sheila M; Miller, Michael; Lee, Phyliss; Leinonen, Kalle; Paquette, Suzanne M; Rodebaugh, Zack; Hahn, Abigail; Gibbs, David L; Slagel, Joseph; Longabaugh, William J; Dhankani, Varsha; Reyes, Madelyn; Pihl, Todd; Backus, Mark; Bookman, Matthew; Deflaux, Nicole; Bingham, Jonathan; Pot, David; Shmulevich, Ilya

2017-11-01

The ISB Cancer Genomics Cloud (ISB-CGC) is one of three pilot projects funded by the National Cancer Institute to explore new approaches to computing on large cancer datasets in a cloud environment. With a focus on Data as a Service, the ISB-CGC offers multiple avenues for accessing and analyzing The Cancer Genome Atlas, TARGET, and other important references such as GENCODE and COSMIC using the Google Cloud Platform. The open approach allows researchers to choose approaches best suited to the task at hand: from analyzing terabytes of data using complex workflows to developing new analysis methods in common languages such as Python, R, and SQL; to using an interactive web application to create synthetic patient cohorts and to explore the wealth of available genomic data. Links to resources and documentation can be found at www.isb-cgc.org Cancer Res; 77(21); e7-10. ©2017 AACR . ©2017 American Association for Cancer Research.

Useful Sensor Web Capabilities to Enable Progressive Mission Autonomy

NASA Technical Reports Server (NTRS)

Mandl, Dan

2007-01-01

This viewgraph presentation reviews using the Sensor Web capabilities as an enabling technology to allow for progressive autonomy of NASA space missions. The presentation reviews technical challenges for future missions, and some of the capabilities that exist to meet those challenges. To establish the ability of the technology to meet the challenges, experiments were conducted on three missions: Earth Observing 1 (EO-1), Cosmic Hot Interstellar Plasma Spectrometer (CHIPS) and Space Technology 5 (ST-5). These experiments are reviewed.

Condensation of cosmic analog material in microgravity conditions - Preliminary analysis of a first set of flights

NASA Technical Reports Server (NTRS)

Mancini, D.; Bussoletti, E.; Mennella, V.; Vittone, A. A.; Colangeli, L.; Mirra, C.; Stephens, J.; Nuth, J.; Lilleleht, L.; Furgeson, F.

1992-01-01

The first results of the STARDUST project, aimed at producing and analyzing cosmic-dust analog materials in microgravity conditions, are summarized. The discussion covers the purpose of the investigation, cosmic-dust formation and properties, previous simulations of cosmic-dust formation, the current approach, the microgravity experimental apparatus, and potential advantages of studying dust formation under microgravity conditions.

Evolution of Mass and Velocity Field in the Cosmic Web: Comparison between Baryonic and Dark Matter

NASA Astrophysics Data System (ADS)

Zhu, Weishan; Feng, Long-Long

2017-03-01

We investigate the evolution of the cosmic web since z = 5 in grid-based cosmological hydrodynamical simulations, focusing on the mass and velocity fields of both baryonic and cold dark matter. The tidal tensor of density is used as the main method for web identification, with λ th = 0.2-1.2. The evolution trends in baryonic and dark matter are similar, although moderate differences are observed. Sheets appear early, and their large-scale pattern may have been set up by z = 3. In terms of mass, filaments supersede sheets as the primary collapsing structures from z ˜ 2-3. Tenuous filaments assembled with each other to form prominent ones at z < 2. In accordance with the construction of the frame of the sheets, the cosmic divergence velocity, v div, was already well-developed above 2-3 Mpc by z = 3. Afterwards, the curl velocity, v curl, grew dramatically along with the rising of filaments, becoming comparable to v div, for <2-3 Mpc at z = 0. The scaling of v curl can be described by the hierarchical turbulence model. The alignment between the vorticity and the eigenvectors of the shear tensor in the baryonic matter field resembles that in the dark matter field, and is even moderately stronger between {\\boldsymbol{ω }} and {{\\boldsymbol{e}}}1, and ω and {{\\boldsymbol{e}}}3. Compared with dark matter, there is slightly less baryonic matter found residing in filaments and clusters, and its vorticity developed more significantly below 2-3 Mpc. These differences may be underestimated because of the limited resolution and lack of star formation in our simulation. The impact of the change of dominant structures in overdense regions at z ˜ 2-3 on galaxy formation and evolution is shortly discussed.

The f ( R ) halo mass function in the cosmic web

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

Braun-Bates, F. von; Winther, H.A.; Alonso, D.

An important indicator of modified gravity is the effect of the local environment on halo properties. This paper examines the influence of the local tidal structure on the halo mass function, the halo orientation, spin and the concentration-mass relation. We use the excursion set formalism to produce a halo mass function conditional on large-scale structure. Our simple model agrees well with simulations on large scales at which the density field is linear or weakly non-linear. Beyond this, our principal result is that f ( R ) does affect halo abundances, the halo spin parameter and the concentration-mass relationship in anmore » environment-independent way, whereas we find no appreciable deviation from \\text(ΛCDM) for the mass function with fixed environment density, nor the alignment of the orientation and spin vectors of the halo to the eigenvectors of the local cosmic web. There is a general trend for greater deviation from \\text(ΛCDM) in underdense environments and for high-mass haloes, as expected from chameleon screening.« less

A database of charged cosmic rays

NASA Astrophysics Data System (ADS)

Maurin, D.; Melot, F.; Taillet, R.

2014-09-01

Aims: This paper gives a description of a new online database and associated online tools (data selection, data export, plots, etc.) for charged cosmic-ray measurements. The experimental setups (type, flight dates, techniques) from which the data originate are included in the database, along with the references to all relevant publications. Methods: The database relies on the MySQL5 engine. The web pages and queries are based on PHP, AJAX and the jquery, jquery.cluetip, jquery-ui, and table-sorter third-party libraries. Results: In this first release, we restrict ourselves to Galactic cosmic rays with Z ≤ 30 and a kinetic energy per nucleon up to a few tens of TeV/n. This corresponds to more than 200 different sub-experiments (i.e., different experiments, or data from the same experiment flying at different times) in as many publications. Conclusions: We set up a cosmic-ray database (CRDB) and provide tools to sort and visualise the data. New data can be submitted, providing the community with a collaborative tool to archive past and future cosmic-ray measurements. http://lpsc.in2p3.fr/crdb; Contact: crdatabase@lpsc.in2p3.fr

Gamma Ray Bursts as Cosmological Probes with EXIST

NASA Astrophysics Data System (ADS)

Hartmann, Dieter; EXIST Team

2006-12-01

The EXIST mission, studied as a Black Hole Finder Probe within NASA's Beyond Einstein Program, would, in its current design, trigger on 1000 Gamma Ray Bursts (GRBs) per year (Grindlay et al, this meeting). The redshift distribution of these GRBs, using results from Swift as a guide, would probe the z > 7 epoch at an event rate of > 50 per year. These bursts trace early cosmic star formation history, point to a first generation of stellar objects that reionize the universe, and provide bright beacons for absorption line studies with groundand space-based observatories. We discuss how EXIST, in conjunction with other space missions and future large survey programs such as LSST, can be utilized to advance our understanding of cosmic chemical evolution, the structure and evolution of the baryonic cosmic web, and the formation of stars in low metallicity environments.

Properties of galaxies reproduced by a hydrodynamic simulation

NASA Astrophysics Data System (ADS)

Vogelsberger, M.; Genel, S.; Springel, V.; Torrey, P.; Sijacki, D.; Xu, D.; Snyder, G.; Bird, S.; Nelson, D.; Hernquist, L.

2014-05-01

Previous simulations of the growth of cosmic structures have broadly reproduced the `cosmic web' of galaxies that we see in the Universe, but failed to create a mixed population of elliptical and spiral galaxies, because of numerical inaccuracies and incomplete physical models. Moreover, they were unable to track the small-scale evolution of gas and stars to the present epoch within a representative portion of the Universe. Here we report a simulation that starts 12 million years after the Big Bang, and traces 13 billion years of cosmic evolution with 12 billion resolution elements in a cube of 106.5 megaparsecs a side. It yields a reasonable population of ellipticals and spirals, reproduces the observed distribution of galaxies in clusters and characteristics of hydrogen on large scales, and at the same time matches the `metal' and hydrogen content of galaxies on small scales.

THE STELLAR SPHEROID, THE DISK, AND THE DYNAMICS OF THE COSMIC WEB

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

Domínguez-Tenreiro, R.; Obreja, A.; Brook, C. B.

Models of the advanced stages of gravitational instability predict that baryons that form the stellar populations of current galaxies at z = 0 displayed a web-like structure at high z, as part of the cosmic web (CW). We explore details of these predictions using cosmological hydrodynamical simulations. When the stellar populations of the spheroid and disk components of simulated late-type galaxies are traced back separately to high zs we found CW-like structures where spheroid progenitors are more evolved than disk progenitors. The distinction between the corresponding stellar populations, as driven by their specific angular momentum content j, can be explainedmore » in terms of the CW evolution, extended to two processes occurring at lower z. First, the spheroid progenitors strongly lose j at collapse, which contrasts with the insignificant j loss of the disk progenitors. The second is related to the lack of alignment, at assembly, between the spheroid-to-be material and the already settled proto-disk, in contrast to the alignment of disk-to-be material, in some cases resulting from circumgalactic, disk-induced gravitational torques. The different final outcomes of these low-z processes have their origins in the different initial conditions driven by the CW dynamics.« less

Mutational Signatures in Cancer (MuSiCa): a web application to implement mutational signatures analysis in cancer samples.

PubMed

Díaz-Gay, Marcos; Vila-Casadesús, Maria; Franch-Expósito, Sebastià; Hernández-Illán, Eva; Lozano, Juan José; Castellví-Bel, Sergi

2018-06-14

Mutational signatures have been proved as a valuable pattern in somatic genomics, mainly regarding cancer, with a potential application as a biomarker in clinical practice. Up to now, several bioinformatic packages to address this topic have been developed in different languages/platforms. MutationalPatterns has arisen as the most efficient tool for the comparison with the signatures currently reported in the Catalogue of Somatic Mutations in Cancer (COSMIC) database. However, the analysis of mutational signatures is nowadays restricted to a small community of bioinformatic experts. In this work we present Mutational Signatures in Cancer (MuSiCa), a new web tool based on MutationalPatterns and built using the Shiny framework in R language. By means of a simple interface suited to non-specialized researchers, it provides a comprehensive analysis of the somatic mutational status of the supplied cancer samples. It permits characterizing the profile and burden of mutations, as well as quantifying COSMIC-reported mutational signatures. It also allows classifying samples according to the above signature contributions. MuSiCa is a helpful web application to characterize mutational signatures in cancer samples. It is accessible online at http://bioinfo.ciberehd.org/GPtoCRC/en/tools.html and source code is freely available at https://github.com/marcos-diazg/musica .

The clustering of galaxies in the completed SDSS-III Baryon Oscillation Spectroscopic Survey: cosmic flows and cosmic web from luminous red galaxies

NASA Astrophysics Data System (ADS)

Ata, Metin; Kitaura, Francisco-Shu; Chuang, Chia-Hsun; Rodríguez-Torres, Sergio; Angulo, Raul E.; Ferraro, Simone; Gil-Marín, Hector; McDonald, Patrick; Hernández Monteagudo, Carlos; Müller, Volker; Yepes, Gustavo; Autefage, Mathieu; Baumgarten, Falk; Beutler, Florian; Brownstein, Joel R.; Burden, Angela; Eisenstein, Daniel J.; Guo, Hong; Ho, Shirley; McBride, Cameron; Neyrinck, Mark; Olmstead, Matthew D.; Padmanabhan, Nikhil; Percival, Will J.; Prada, Francisco; Rossi, Graziano; Sánchez, Ariel G.; Schlegel, David; Schneider, Donald P.; Seo, Hee-Jong; Streblyanska, Alina; Tinker, Jeremy; Tojeiro, Rita; Vargas-Magana, Mariana

2017-06-01

We present a Bayesian phase-space reconstruction of the cosmic large-scale matter density and velocity fields from the Sloan Digital Sky Survey-III Baryon Oscillations Spectroscopic Survey Data Release 12 CMASS galaxy clustering catalogue. We rely on a given Λ cold dark matter cosmology, a mesh resolution in the range of 6-10 h-1 Mpc, and a lognormal-Poisson model with a redshift-dependent non-linear bias. The bias parameters are derived from the data and a general renormalized perturbation theory approach. We use combined Gibbs and Hamiltonian sampling, implemented in the argo code, to iteratively reconstruct the dark matter density field and the coherent peculiar velocities of individual galaxies, correcting hereby for coherent redshift space distortions. Our tests relying on accurate N-body-based mock galaxy catalogues show unbiased real space power spectra of the non-linear density field up to k ˜ 0.2 h Mpc-1, and vanishing quadrupoles down to r ˜ 20 h-1 Mpc. We also demonstrate that the non-linear cosmic web can be obtained from the tidal field tensor based on the Gaussian component of the reconstructed density field. We find that the reconstructed velocities have a statistical correlation coefficient compared to the true velocities of each individual light-cone mock galaxy of r ˜ 0.68 including about 10 per cent of satellite galaxies with virial motions (about r = 0.75 without satellites). The power spectra of the velocity divergence agree well with theoretical predictions up to k ˜ 0.2 h Mpc-1. This work will be especially useful to improve, for example, baryon acoustic oscillation reconstructions, kinematic Sunyaev-Zeldovich, integrated Sachs-Wolfe measurements or environmental studies.

Observing gas in Cosmic Web filaments to constrain simulations of cosmic structure formation

NASA Astrophysics Data System (ADS)

Wakker, Bart

2016-10-01

Cosmological simulations predict that dark matter and baryons condense into multi-Mpc filamentary structures, making up the Cosmic Web. This is outlined by dark matter halos, inside which 10% of baryons are concentrated to make stars in galaxies. The other 90% of the baryons remain gaseous, with about half located outside galaxy halos. They can be traced by Lyman alpha absorbers, whose HI column density is determined by a combination of gas density and the intensity of the extragalactic ionizing background (EGB). About 1000 HST orbits have been expended to map the 50% of baryons in galaxy halos. This contrasts with 37 orbits explicitly allocated to map the other 50% (our Cycle 18 program to observe 17 AGN projected onto a single filament at cz 3500 km/s). We propose a 68-orbit program to observe 40 AGN, creating a sample of 56 sightlines covering a second filament at cz 2500 km/s. Using this dataset we will do the following: (1) measure the intensity of the EGB to within about 50%; (2) confirm that the linewidth of Lya absorbers increases near the filament axis, suggesting increasing temperature or turbulence; (3) check our earlier finding that simulations predict a transverse density HI profile (which scales with the dark-matter profile) that is much broader than is indicated by the observations.

WebCN: A web-based computation tool for in situ-produced cosmogenic nuclides

NASA Astrophysics Data System (ADS)

Ma, Xiuzeng; Li, Yingkui; Bourgeois, Mike; Caffee, Marc; Elmore, David; Granger, Darryl; Muzikar, Paul; Smith, Preston

2007-06-01

Cosmogenic nuclide techniques are increasingly being utilized in geoscience research. For this it is critical to establish an effective, easily accessible and well defined tool for cosmogenic nuclide computations. We have been developing a web-based tool (WebCN) to calculate surface exposure ages and erosion rates based on the nuclide concentrations measured by the accelerator mass spectrometry. WebCN for 10Be and 26Al has been finished and published at http://www.physics.purdue.edu/primelab/for_users/rockage.html. WebCN for 36Cl is under construction. WebCN is designed as a three-tier client/server model and uses the open source PostgreSQL for the database management and PHP for the interface design and calculations. On the client side, an internet browser and Microsoft Access are used as application interfaces to access the system. Open Database Connectivity is used to link PostgreSQL and Microsoft Access. WebCN accounts for both spatial and temporal distributions of the cosmic ray flux to calculate the production rates of in situ-produced cosmogenic nuclides at the Earth's surface.

Cosmic Origins Program Annual Technology Report

NASA Technical Reports Server (NTRS)

Pham, Bruce Thai; Neff, Susan Gale

2015-01-01

What is the Cosmic Origins (COR) Program? From ancient times, humans have looked up at the night sky and wondered: Are we alone? How did the universe come to be? How does the universe work? COR focuses on the second question. Scientists investigating this broad theme seek to understand the origin and evolution of the universe from the Big Bang to the present day, determining how the expanding universe grew into a grand cosmic web of dark matter enmeshed with galaxies and pristine gas, forming, merging, and evolving over time. COR also seeks to understand how stars and planets form from clouds in these galaxies to create the heavy elements that are essential to life starting with the first generation of stars to seed the universe, and continuing through the birth and eventual death of all subsequent generations of stars. The COR Programs purview includes the majority of the field known as astronomy, from antiquity to the present.

Program Annual Technology Report: Cosmic Origins Program Office

NASA Technical Reports Server (NTRS)

Pham, Thai; Neff, Susan

2017-01-01

What is the Cosmic Origins (COR) Program? From ancient times, humans have looked up at the night sky and wondered: Are we alone? How did the universe come to be? How does the universe work? COR focuses on the second question. Scientists investigating this broad theme seek to understand the origin and evolution of the universe from the Big Bang to the present day, determining how the expanding universe grew into a grand cosmic web of dark matter enmeshed with galaxies and pristine gas, forming, merging, and evolving over time. COR also seeks to understand how stars and planets form from clouds in these galaxies to create the heavy elements that are essential to life, starting with the first generation of stars to seed the universe, and continuing through the birth and eventual death of all subsequent generations of stars. The COR Programs purview includes the majority of the field known as astronomy.

KCDC — The KASCADE Cosmic-ray Data Centre

NASA Astrophysics Data System (ADS)

Haungs, A.; Blumer, J.; Fuchs, B.; Kang, D.; Schoo, S.; Wochele, D.; Wochele, J.; Apel, W. D.; Arteaga-Velázquez, J. C.; Bekk, K.; Bertaina, M.; Bozdog, H.; Brancus, I. M.; Cantoni, E.; Chiavassa, A.; Cossavella, F.; Daumiller, K.; de Souza, V.; Di Pierro, F.; Doll, P.; Engel, R.; Fuhrmann, D.; Gherghel-Lascu, A.; Gils, H. J.; Glasstetter, R.; Grupen, C.; Heck, D.; Hörandel, J. R.; Huber, D.; Huege, T.; Kampert, K. H.; Klages, H. O.; Link, K.; Łuczak, P.; Mathes, H. J.; Mayer, H. J.; Milke, J.; Mitrica, B.; Morello, C.; Oehlschläger, J.; Ostapchenko, S.; Palmieri, N.; Petcu, M.; Pierog, T.; Rebel, H.; Roth, M.; Schieler, H.; Schröder, F. G.; Sima, O.; Toma, G.; Trinchero, G. C.; Ulrich, H.; Weindl, A.; Zabierowski, J.

2015-08-01

KCDC, the ‘KASCADE Cosmic-ray Data Centre’, is a web portal, where data of astroparticle physics experiments will be made available for the interested public. The KASCADE experiment, financed by public money, was a large-area detector for the measurement of high-energy cosmic rays via the detection of air showers. KASCADE and its extension KASCADE-Grande stopped finally the active data acquisition of all its components including the radio EAS experiment LOPES end of 2012 after more than 20 years of data taking. In a first release, with KCDC we provide to the public the measured and reconstructed parameters of more than 160 million air showers. In addition, KCDC provides the conceptional design, how the data can be treated and processed so that they are also usable outside the community of experts in the research field. Detailed educational examples make a use also possible for high-school students and early stage researchers.

Properties of galaxies reproduced by a hydrodynamic simulation.

PubMed

Vogelsberger, M; Genel, S; Springel, V; Torrey, P; Sijacki, D; Xu, D; Snyder, G; Bird, S; Nelson, D; Hernquist, L

2014-05-08

Previous simulations of the growth of cosmic structures have broadly reproduced the 'cosmic web' of galaxies that we see in the Universe, but failed to create a mixed population of elliptical and spiral galaxies, because of numerical inaccuracies and incomplete physical models. Moreover, they were unable to track the small-scale evolution of gas and stars to the present epoch within a representative portion of the Universe. Here we report a simulation that starts 12 million years after the Big Bang, and traces 13 billion years of cosmic evolution with 12 billion resolution elements in a cube of 106.5 megaparsecs a side. It yields a reasonable population of ellipticals and spirals, reproduces the observed distribution of galaxies in clusters and characteristics of hydrogen on large scales, and at the same time matches the 'metal' and hydrogen content of galaxies on small scales.

Cosmically-Poetic and Poetical Visions with the Emphasys on Anthology "The Cosmic Flower"

NASA Astrophysics Data System (ADS)

Cvetković, Nikola

2005-10-01

It is considered first the tradition to sing to cosmos, with the emphasys of the folk one, Njegos etc. Than the development from the section "Few poetry" in the journal Vasiona (Universe) to the anthology The cosmic flower is presented. In the final part, this anthology is analyzed with a pozitive estimate of its value and significance.

Morphological statistics of the cosmic web

NASA Astrophysics Data System (ADS)

Shandarin, Sergei F.

2004-07-01

We report the first systematic study of the supercluster-void network in the ΛCDM concordance cosmology treating voids and superclusters on an equal footing. We study the dark matter density field in real space smoothed with the Ls = 5 h[minus sign]1Mpc Gaussian window. Superclusters and voids are defined as individual members of over-dense and under-dense excursion sets respectively. We determine the morphological properties of the cosmic web at a large number of dark matter density levels by computing Minkowski functionals for every supercluster and void. At the adopted smoothing scale individual superclusters totally occupy no more than about 5% of the total volume and contain no more than 20% of mass if the largest supercluster is excluded. Likewise, individual voids totally occupy no more than 14% of volume and contain no more than 4% of mass if the largest void is excluded. The genus of individual superclusters can be ˜ 5 while the genus of individual voids reaches ˜ 55, implying significant amount of substructure in superclusters and especially in voids. Large voids are typically distinctly non-spherical.

Cosmic radiation and cancer: is there a link?

PubMed

Di Trolio, Rossella; Di Lorenzo, Giuseppe; Fumo, Bruno; Ascierto, Paolo A

2015-01-01

Cosmic radiation can cause genetic and cytogenetic damage. Certain occupations including airline pilots and cabin crew are acknowledged to have a greater exposure to cosmic radiation. In a systematic search of MEDLINE, performed from 1990 to 2014, we analyzed clinical studies using the keywords: cosmic radiation, cancer, chromosome aberration, pilots and astronauts. Increased incidence of skin cancers among airline cabin crew has been reported in a number of studies and appears to be the most consistent finding. However, as with other cancers, it is unclear whether increased exposure to cosmic radiation is a factor in the increased incidence or whether this can be explained by lifestyle factors. Further research is needed to clarify the risk of cancer in relation to cosmic radiation.

Uneven flows: On cosmic bulk flows, local observers, and gravity

NASA Astrophysics Data System (ADS)

Hellwing, Wojciech A.; Bilicki, Maciej; Libeskind, Noam I.

2018-05-01

Using N -body simulations we study the impact of various systematic effects on the low-order moments of the cosmic velocity field: the bulk flow (BF) and the cosmic Mach number (CMN). We consider two types of systematics: those related to survey properties and those induced by the observer's location in the Universe. In the former category we model sparse sampling, velocity errors, and survey incompleteness (radial and geometrical). In the latter, we consider local group (LG) analogue observers, placed in a specific location within the cosmic web, satisfying various observational criteria. We differentiate such LG observers from Copernican ones, who are at random locations. We report strong systematic effects on the measured BF and CMN induced by sparse sampling, velocity errors and radial incompleteness. For BF most of these effects exceed 10% for scales R ≲100 h-1 Mpc . For CMN some of these systematics can be catastrophically large (i.e., >50 %) also on bigger scales. Moreover, we find that the position of the observer in the cosmic web significantly affects the locally measured BF (CMN), with effects as large as ˜20 % (30 % ) at R ≲50 h-1 Mpc for a LG-like observer as compared to a random one. This effect is comparable to the sample variance at the same scales. Such location-dependent effects have not been considered previously in BF and CMN studies and here we report their magnitude and scale for the first time. To highlight the importance of these systematics, we additionally study a model of modified gravity with ˜15 % enhanced growth rate (compared to general relativity). We found that the systematic effects can mimic the modified gravity signal. The worst-case scenario is realized for a case of a LG-like observer, when the effects induced by local structures are degenerate with the enhanced growth rate fostered by modified gravity. Our results indicate that dedicated constrained simulations and realistic mock galaxy catalogs will be absolutely necessary to fully benefit from the statistical power of the forthcoming peculiar velocity data from surveys such as TAIPAN, WALLABY, COSMICFLOWS-4 and SKA.

The detection of the imprint of filaments on cosmic microwave background lensing

NASA Astrophysics Data System (ADS)

He, Siyu; Alam, Shadab; Ferraro, Simone; Chen, Yen-Chi; Ho, Shirley

2018-05-01

Galaxy redshift surveys, such as the 2-Degree-Field Survey (2dF)1, Sloan Digital Sky Survey (SDSS)2, 6-Degree-Field Survey (6dF)3, Galaxy And Mass Assembly survey (GAMA)4 and VIMOS Public Extragalactic Redshift Survey (VIPERS)5, have shown that the spatial distribution of matter forms a rich web, known as the cosmic web6. Most galaxy survey analyses measure the amplitude of galaxy clustering as a function of scale, ignoring information beyond a small number of summary statistics. Because the matter density field becomes highly non-Gaussian as structure evolves under gravity, we expect other statistical descriptions of the field to provide us with additional information. One way to study the non-Gaussianity is to study filaments, which evolve non-linearly from the initial density fluctuations produced in the primordial Universe. In our study, we report the detection of lensing of the cosmic microwave background (CMB) by filaments, and we apply a null test to confirm our detection. Furthermore, we propose a phenomenological model to interpret the detected signal, and we measure how filaments trace the matter distribution on large scales through filament bias, which we measure to be around 1.5. Our study provides new scope to understand the environmental dependence of galaxy formation. In the future, the joint analysis of lensing and Sunyaev-Zel'dovich observations might reveal the properties of `missing baryons', the vast majority of the gas that resides in the intergalactic medium, which has so far evaded most observations.

Investigating the Cosmic Web with Topological Data Analysis

NASA Astrophysics Data System (ADS)

Cisewski-Kehe, Jessi; Wu, Mike; Fasy, Brittany; Hellwing, Wojciech; Lovell, Mark; Rinaldo, Alessandro; Wasserman, Larry

2018-01-01

Data exhibiting complicated spatial structures are common in many areas of science (e.g. cosmology, biology), but can be difficult to analyze. Persistent homology is a popular approach within the area of Topological Data Analysis that offers a new way to represent, visualize, and interpret complex data by extracting topological features, which can be used to infer properties of the underlying structures. In particular, TDA may be useful for analyzing the large-scale structure (LSS) of the Universe, which is an intricate and spatially complex web of matter. In order to understand the physics of the Universe, theoretical and computational cosmologists develop large-scale simulations that allow for visualizing and analyzing the LSS under varying physical assumptions. Each point in the 3D data set represents a galaxy or a cluster of galaxies, and topological summaries ("persistent diagrams") can be obtained summarizing the different ordered holes in the data (e.g. connected components, loops, voids).The topological summaries are interesting and informative descriptors of the Universe on their own, but hypothesis tests using the topological summaries would provide a way to make more rigorous comparisons of LSS under different theoretical models. For example, the received cosmological model has cold dark matter (CDM); however, while the case is strong for CDM, there are some observational inconsistencies with this theory. Another possibility is warm dark matter (WDM). It is of interest to see if a CDM Universe and WDM Universe produce LSS that is topologically distinct.We present several possible test statistics for two-sample hypothesis tests using the topological summaries, carryout a simulation study to investigate the suitableness of the proposed test statistics using simulated data from a variation of the Voronoi foam model, and finally we apply the proposed inference framework to WDM vs. CDM cosmological simulation data.

The effect of the neutral sheet structure of the interplanetary magnetic field on cosmic ray distribution in space

NASA Technical Reports Server (NTRS)

Alania, M. V.; Aslamazashvili, R. G.; Bochorishvili, T.; Djapiashvili, T. V.; Tkemaladze, V. S.

1985-01-01

Results of the numerical solution of the anistoropic diffusion equation are presented. The modulation depth of galactic cosmic rays is defined by the degree of curvature of the neutral current sheet in the heliosphere. The effect of the regular interplanetary magnetic field (IMF) on cosmic ray anisotropy in the period of solar activity minimum (in 1976) is analyzed by the data of the neutron super-monitors of the world network, and the heliolatitudinal gradient and cosmic ray diffusion coefficient are defined.

The rarity of Dark Matter Halos in medium-sized walls of the cosmic web

NASA Astrophysics Data System (ADS)

Goh, Tze; Primack, Joel R.; Lee, Christoph; Aragon-Calvo, Miguel A.; Behroozi, Peter

2017-01-01

In 2014, Marshall McCall mapped out our Local Sheet, the cosmic wall containing the Milk Way and Andromeda galaxies. We use the large new Bolshoi-Planck cosmological simulation to investigate how rare our type of Local Sheet is, with 2 nearby halos like those of Milky Way and Andromeda. The conclusion of our investigation is that the occurrence of a pair of galaxies the size of Milky Way and Andromeda near the center of a wall 8 mpc in diameter, with the pair of galaxies within 0.7 mpc/h of each other, is very rare : it makes up only 0.05% of all walls in the simulation.

The Zeldovich & Adhesion approximations and applications to the local universe

NASA Astrophysics Data System (ADS)

Hidding, Johan; van de Weygaert, Rien; Shandarin, Sergei

2016-10-01

The Zeldovich approximation (ZA) predicts the formation of a web of singularities. While these singularities may only exist in the most formal interpretation of the ZA, they provide a powerful tool for the analysis of initial conditions. We present a novel method to find the skeleton of the resulting cosmic web based on singularities in the primordial deformation tensor and its higher order derivatives. We show that the A 3 lines predict the formation of filaments in a two-dimensional model. We continue with applications of the adhesion model to visualise structures in the local (z < 0.03) universe.

The Parker Instability with Cosmic-Ray Streaming

NASA Astrophysics Data System (ADS)

Heintz, Evan; Zweibel, Ellen G.

2018-06-01

Recent studies have found that cosmic-ray transport plays an important role in feedback processes such as star formation and the launching of galactic winds. Although cosmic-ray buoyancy is widely held to be a destabilizing force in galactic disks, the effect of cosmic-ray transport on the stability of stratified systems has yet to be analyzed. We perform a stability analysis of a stratified layer for three different cosmic-ray transport models: decoupled (Classic Parker), coupled with γ c = 4/3 but not streaming (Modified Parker), and finally coupled with streaming at the Alfvén speed. When the compressibility of the cosmic rays is decreased the system becomes much more stable, but the addition of cosmic-ray streaming to the Parker instability severely destabilizes it. Through comparison of these three cases and analysis of the work contributions for the perturbed quantities of each system, we demonstrate that cosmic-ray heating of the gas is responsible for the destabilization of the system. We find that a 3D system is unstable over a larger range of wavelengths than the 2D system. Therefore, the Parker instability with cosmic-ray streaming may play an important role in cosmic-ray feedback.

Measurement of the flux of ultra high energy cosmic rays by the stereo technique

NASA Astrophysics Data System (ADS)

High Resolution Fly'S Eye Collaboration; Abbasi, R. U.; Abu-Zayyad, T.; Al-Seady, M.; Allen, M.; Amann, J. F.; Archbold, G.; Belov, K.; Belz, J. W.; Bergman, D. R.; Blake, S. A.; Brusova, O. A.; Burt, G. W.; Cannon, C.; Cao, Z.; Deng, W.; Fedorova, Y.; Findlay, J.; Finley, C. B.; Gray, R. C.; Hanlon, W. F.; Hoffman, C. M.; Holzscheiter, M. H.; Hughes, G.; Hüntemeyer, P.; Ivanov, D.; Jones, B. F.; Jui, C. C. H.; Kim, K.; Kirn, M. A.; Loh, E. C.; Maestas, M. M.; Manago, N.; Marek, L. J.; Martens, K.; Matthews, J. A. J.; Matthews, J. N.; Moore, S. A.; O'Neill, A.; Painter, C. A.; Perera, L.; Reil, K.; Riehle, R.; Roberts, M. D.; Rodriguez, D.; Sasaki, M.; Schnetzer, S. R.; Scott, L. M.; Sinnis, G.; Smith, J. D.; Snow, R.; Sokolsky, P.; Springer, R. W.; Stokes, B. T.; Stratton, S. R.; Thomas, J. R.; Thomas, S. B.; Thomson, G. B.; Tupa, D.; Wiencke, L. R.; Zech, A.; Zhang, B. K.; Zhang, X.; Zhang, Y.; High Resolution Fly's Eye Collaboration

2009-08-01

The High Resolution Fly’s Eye (HiRes) experiment has measured the flux of ultrahigh energy cosmic rays using the stereoscopic air fluorescence technique. The HiRes experiment consists of two detectors that observe cosmic ray showers via the fluorescence light they emit. HiRes data can be analyzed in monocular mode, where each detector is treated separately, or in stereoscopic mode where they are considered together. Using the monocular mode the HiRes collaboration measured the cosmic ray spectrum and made the first observation of the Greisen-Zatsepin-Kuzmin cutoff. In this paper we present the cosmic ray spectrum measured by the stereoscopic technique. Good agreement is found with the monocular spectrum in all details.

Baryons at the edge of the X-ray-brightest galaxy cluster.

PubMed

Simionescu, Aurora; Allen, Steven W; Mantz, Adam; Werner, Norbert; Takei, Yoh; Morris, R Glenn; Fabian, Andrew C; Sanders, Jeremy S; Nulsen, Paul E J; George, Matthew R; Taylor, Gregory B

2011-03-25

Studies of the diffuse x-ray-emitting gas in galaxy clusters have provided powerful constraints on cosmological parameters and insights into plasma astrophysics. However, measurements of the faint cluster outskirts have become possible only recently. Using data from the Suzaku x-ray telescope, we determined an accurate, spatially resolved census of the gas, metals, and dark matter out to the edge of the Perseus Cluster. Contrary to previous results, our measurements of the cluster baryon fraction are consistent with the expected universal value at half of the virial radius. The apparent baryon fraction exceeds the cosmic mean at larger radii, suggesting a clumpy distribution of the gas, which is important for understanding the ongoing growth of clusters from the surrounding cosmic web.

KSC-08pd2189

NASA Image and Video Library

2008-07-29

CAPE CANAVERAL, Fla. – At NASA's Kennedy Space Center, workers from NASA's Goddard Space Flight Center roll the Cosmic Origins Spectrograph, or COS, into the clean room of the Payload Hazardous Servicing Facility. The COS will be installed on the Hubble Space Telescope on space shuttle Atlantis' STS-125 mission. COS will be the most sensitive ultraviolet spectrograph ever flown on Hubble and will probe the "cosmic web" - the large-scale structure of the universe whose form is determined by the gravity of dark matter and is traced by galaxies and intergalactic gas. COS's far-ultraviolet channel has a sensitivity 30 times greater than that of previous spectroscopic instruments for the detection of extremely low light levels. Launch of STS-125 is targeted for Oct. 8. Photo credit: NASA/Jack Pfaller

Hydrodynamical simulations of coupled and uncoupled quintessence models - I. Halo properties and the cosmic web

NASA Astrophysics Data System (ADS)

Carlesi, Edoardo; Knebe, Alexander; Lewis, Geraint F.; Wales, Scott; Yepes, Gustavo

2014-04-01

We present the results of a series of adiabatic hydrodynamical simulations of several quintessence models (both with a free and an interacting scalar field) in comparison to a standard Λ cold dark matter cosmology. For each we use 2 × 10243 particles in a 250 h-1 Mpc periodic box assuming 7-year Wilkinson Microwave Anisotropy Probe cosmology. In this work we focus on the properties of haloes in the cosmic web at z = 0. The web is classified into voids, sheets, filaments and knots depending on the eigenvalues of the velocity shear tensor, which are an excellent proxy for the underlying overdensity distribution. We find that the properties of objects classified according to their surrounding environment show a substantial dependence on the underlying cosmology; for example, while Vmax shows average deviations of ≈5 per cent across the different models when considering the full halo sample, comparing objects classified according to their environment, the size of the deviation can be as large as 20 per cent. We also find that halo spin parameters are positively correlated to the coupling, whereas halo concentrations show the opposite behaviour. Furthermore, when studying the concentration-mass relation in different environments, we find that in all cosmologies underdense regions have a larger normalization and a shallower slope. While this behaviour is found to characterize all the models, differences in the best-fitting relations are enhanced in (coupled) dark energy models, thus providing a clearer prediction for this class of models.

Percolation analysis for cosmic web with discrete points

NASA Astrophysics Data System (ADS)

Zhang, Jiajun; Cheng, Dalong; Chu, Ming-Chung

2016-03-01

Percolation analysis has long been used to quantify the connectivity of the cosmic web. Unlike most of the previous works using density field on grids, we have studied percolation analysis based on discrete points. Using a Friends-of-Friends (FoF) algorithm, we generate the S-bb relation, between the fractional mass of the largest connected group (S) and the FoF linking length (bb). We propose a new model, the Probability Cloud Cluster Expansion Theory (PCCET) to relate the S-bb relation with correlation functions. We show that the S-bb relation reflects a combination of all orders of correlation functions. We have studied the S-bb relation with simulation and find that the S-bb relation is robust against redshift distortion and incompleteness in observation. From the Bolshoi simulation, with Halo Abundance Matching (HAM), we have generated a mock galaxy catalogue. Good matching of the projected two-point correlation function with observation is confirmed. However, comparing the mock catalogue with the latest galaxy catalogue from SDSS DR12, we have found significant differences in their S-bb relations. This indicates that the mock catalogue cannot accurately recover higher order correlation functions than the two-point correlation function, which reveals the limit of HAM method.

A Two-Tiered Model for Analyzing Library Web Site Usage Statistics, Part 1: Web Server Logs.

ERIC Educational Resources Information Center

Cohen, Laura B.

2003-01-01

Proposes a two-tiered model for analyzing web site usage statistics for academic libraries: one tier for library administrators that analyzes measures indicating library use, and a second tier for web site managers that analyzes measures aiding in server maintenance and site design. Discusses the technology of web site usage statistics, and…

Cosmic string catalysis of skyrmion decay

NASA Technical Reports Server (NTRS)

Gregory, Ruth; Davis, Anne-Christine; Brandenberger, Robert

1988-01-01

The Callan-Witten picture is developed for monopole catalyzed skyrmion decay in order to analyze the corresponding cosmic string scenario. It is discovered that cosmic strings (both ordinary and superconducting) can catalyze proton decay, but that this catalysis only occurs on the scale of the core of the string. In order to do this we have to develop a vortex model for the superconducting string. An argument is also given for the difference in the enhancement factors for monopoles and strings.

Temperature Effect in Secondary Cosmic Rays (MUONS) Observed at the Ground: Analysis of the Global MUON Detector Network Data

NASA Astrophysics Data System (ADS)

de Mendonça, R. R. S.; Braga, C. R.; Echer, E.; Dal Lago, A.; Munakata, K.; Kuwabara, T.; Kozai, M.; Kato, C.; Rockenbach, M.; Schuch, N. J.; Jassar, H. K. Al; Sharma, M. M.; Tokumaru, M.; Duldig, M. L.; Humble, J. E.; Evenson, P.; Sabbah, I.

2016-10-01

The analysis of cosmic ray intensity variation seen by muon detectors at Earth's surface can help us to understand astrophysical, solar, interplanetary and geomagnetic phenomena. However, before comparing cosmic ray intensity variations with extraterrestrial phenomena, it is necessary to take into account atmospheric effects such as the temperature effect. In this work, we analyzed this effect on the Global Muon Detector Network (GMDN), which is composed of four ground-based detectors, two in the northern hemisphere and two in the southern hemisphere. In general, we found a higher temperature influence on detectors located in the northern hemisphere. Besides that, we noticed that the seasonal temperature variation observed at the ground and at the altitude of maximum muon production are in antiphase for all GMDN locations (low-latitude regions). In this way, contrary to what is expected in high-latitude regions, the ground muon intensity decrease occurring during summertime would be related to both parts of the temperature effect (the negative and the positive). We analyzed several methods to describe the temperature effect on cosmic ray intensity. We found that the mass weighted method is the one that best reproduces the seasonal cosmic ray variation observed by the GMDN detectors and allows the highest correlation with long-term variation of the cosmic ray intensity seen by neutron monitors.

THE TEMPERATURE EFFECT IN SECONDARY COSMIC RAYS (MUONS) OBSERVED AT THE GROUND: ANALYSIS OF THE GLOBAL MUON DETECTOR NETWORK DATA

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

De Mendonça, R. R. S.; Braga, C. R.; Echer, E.

2016-10-20

The analysis of cosmic ray intensity variation seen by muon detectors at Earth's surface can help us to understand astrophysical, solar, interplanetary and geomagnetic phenomena. However, before comparing cosmic ray intensity variations with extraterrestrial phenomena, it is necessary to take into account atmospheric effects such as the temperature effect. In this work, we analyzed this effect on the Global Muon Detector Network (GMDN), which is composed of four ground-based detectors, two in the northern hemisphere and two in the southern hemisphere. In general, we found a higher temperature influence on detectors located in the northern hemisphere. Besides that, we noticedmore » that the seasonal temperature variation observed at the ground and at the altitude of maximum muon production are in antiphase for all GMDN locations (low-latitude regions). In this way, contrary to what is expected in high-latitude regions, the ground muon intensity decrease occurring during summertime would be related to both parts of the temperature effect (the negative and the positive). We analyzed several methods to describe the temperature effect on cosmic ray intensity. We found that the mass weighted method is the one that best reproduces the seasonal cosmic ray variation observed by the GMDN detectors and allows the highest correlation with long-term variation of the cosmic ray intensity seen by neutron monitors.« less

Energetic Nuclei, Superdensity and Biomedicine

ERIC Educational Resources Information Center

Baldin, A. M.

1977-01-01

High-energy, relativistic nuclei were first observed in cosmic rays. Studing these nuclei has provided an opportunity for analyzing the composition of cosmic rays and for experimentally verifying principles governing the behavior of nuclear matter at high and super-high temperatures. Medical research using accelerated nuclei is suggested.…

Straight spinning cosmic strings in Brans-Dicke gravity

NASA Astrophysics Data System (ADS)

Dos Santos, S. Mittmann; da Silva, J. M. Hoff; Cindra, J. L.

2018-03-01

An exact solution of straight spinning cosmic strings in Brans-Dicke theory of gravitation is presented. The possibility of the existence of closed time-like curves around these cosmic strings is analyzed. Furthermore, the stability about the formation of the topological defect discussed here is checked. It is shown that the existence of a suitable choice for the integration constants in which closed time-like curves are not allowed. We also study the (im)possibility of using the obtained spacetime in the rotational curves problem.

Alignments of the galaxies in and around the Virgo cluster with the local velocity shear

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

Lee, Jounghun; Rey, Soo Chang; Kim, Suk, E-mail: jounghun@astro.snu.ac.kr

2014-08-10

Observational evidence is presented for the alignment between the cosmic sheet and the principal axis of the velocity shear field at the position of the Virgo cluster. The galaxies in and around the Virgo cluster from the Extended Virgo Cluster Catalog that was recently constructed by Kim et al. are used to determine the direction of the local sheet. The peculiar velocity field reconstructed from the Sloan Digital Sky Survey Data Release 7 is analyzed to estimate the local velocity shear tensor at the Virgo center. Showing first that the minor principal axis of the local velocity shear tensor ismore » almost parallel to the direction of the line of sight, we detect a clear signal of alignment between the positions of the Virgo satellites and the intermediate principal axis of the local velocity shear projected onto the plane of the sky. Furthermore, the dwarf satellites are found to appear more strongly aligned than their normal counterparts, which is interpreted as an indication of the following. (1) The normal satellites and the dwarf satellites fall in the Virgo cluster preferentially along the local filament and the local sheet, respectively. (2) The local filament is aligned with the minor principal axis of the local velocity shear while the local sheet is parallel to the plane spanned by the minor and intermediate principal axes. Our result is consistent with the recent numerical claim that the velocity shear is a good tracer of the cosmic web.« less

Bruce Grossan's Home Page

Science.gov Websites

Generation Rapid-Optical Response GRB Mission (ADS link) now on web (i.e. arxiv link). First Spitzer Paper the Infra-Red (2.1 micron K' band), taken at the Wyoming IR Observatory (WIRO) 4/16/94. The galaxy is largest, most sensitive map of a low-dust region made with the Spitzer 160 µm Camera. The cosmic far-IR

KSC-08pd2182

NASA Image and Video Library

2008-07-29

CAPE CANAVERAL, Fla. – In the airlock of the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center, workers from NASA's Goddard Space Flight Center remove the top from the transportation canister in which the Cosmic Origins Spectrograph, or COS, arrived. The COS will be installed on the Hubble Space Telescope on space shuttle Atlantis' STS-125 mission. COS will be the most sensitive ultraviolet spectrograph ever flown on Hubble and will probe the "cosmic web" - the large-scale structure of the universe whose form is determined by the gravity of dark matter and is traced by galaxies and intergalactic gas. COS's far-ultraviolet channel has a sensitivity 30 times greater than that of previous spectroscopic instruments for the detection of extremely low light levels. Launch of STS-125 is targeted for Oct. 8. Photo credit: NASA/Jack Pfaller

KSC-08pd2190

NASA Image and Video Library

2008-07-29

CAPE CANAVERAL, Fla. – At NASA's Kennedy Space Center, workers from NASA's Goddard Space Flight Center roll the Cosmic Origins Spectrograph, or COS, into position in the clean room of the Payload Hazardous Servicing Facility for instrument testing. The COS will be installed on the Hubble Space Telescope on space shuttle Atlantis' STS-125 mission. COS will be the most sensitive ultraviolet spectrograph ever flown on Hubble and will probe the "cosmic web" - the large-scale structure of the universe whose form is determined by the gravity of dark matter and is traced by galaxies and intergalactic gas. COS's far-ultraviolet channel has a sensitivity 30 times greater than that of previous spectroscopic instruments for the detection of extremely low light levels. Launch of STS-125 is targeted for Oct. 8. Photo credit: NASA/Jack Pfaller

KSC-08pd2185

NASA Image and Video Library

2008-07-29

CAPE CANAVERAL, Fla. – In the airlock of the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center, workers from NASA's Goddard Space Flight Center prepare to lift the Cosmic Origins Spectrograph, or COS, from its transportation canister. The COS will be installed on the Hubble Space Telescope on space shuttle Atlantis' STS-125 mission. COS will be the most sensitive ultraviolet spectrograph ever flown on Hubble and will probe the "cosmic web" - the large-scale structure of the universe whose form is determined by the gravity of dark matter and is traced by galaxies and intergalactic gas. COS's far-ultraviolet channel has a sensitivity 30 times greater than that of previous spectroscopic instruments for the detection of extremely low light levels. Launch of STS-125 is targeted for Oct. 8. Photo credit: NASA/Jack Pfaller

KSC-08pd2181

NASA Image and Video Library

2008-07-29

CAPE CANAVERAL, Fla. – In the airlock of the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center, workers from NASA's Goddard Space Flight Center open the transportation canister in which the Cosmic Origins Spectrograph, or COS, is protected. The COS will be installed on the Hubble Space Telescope on space shuttle Atlantis' STS-125 mission. COS will be the most sensitive ultraviolet spectrograph ever flown on Hubble and will probe the "cosmic web" - the large-scale structure of the universe whose form is determined by the gravity of dark matter and is traced by galaxies and intergalactic gas. COS's far-ultraviolet channel has a sensitivity 30 times greater than that of previous spectroscopic instruments for the detection of extremely low light levels. Launch of STS-125 is targeted for Oct. 8. Photo credit: NASA/Jack Pfaller

Collisionless Dynamics and the Cosmic Web

NASA Astrophysics Data System (ADS)

Hahn, Oliver

2016-10-01

I review the nature of three-dimensional collapse in the Zeldovich approximation, how it relates to the underlying nature of the three-dimensional Lagrangian manifold and naturally gives rise to a hierarchical structure formation scenario that progresses through collapse from voids to pancakes, filaments and then halos. I then discuss how variations of the Zeldovich approximation (based on the gravitational or the velocity potential) have been used to define classifications of the cosmic large-scale structure into dynamically distinct parts. Finally, I turn to recent efforts to devise new approaches relying on tessellations of the Lagrangian manifold to follow the fine-grained dynamics of the dark matter fluid into the highly non-linear regime and both extract the maximum amount of information from existing simulations as well as devise new simulation techniques for cold collisionless dynamics.

KSC-08pd2184

NASA Image and Video Library

2008-07-29

CAPE CANAVERAL, Fla. – In the airlock of the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center, workers from NASA's Goddard Space Flight Center prepare to remove the Cosmic Origins Spectrograph, or COS, from its transportation canister. The COS will be installed on the Hubble Space Telescope on space shuttle Atlantis' STS-125 mission. COS will be the most sensitive ultraviolet spectrograph ever flown on Hubble and will probe the "cosmic web" - the large-scale structure of the universe whose form is determined by the gravity of dark matter and is traced by galaxies and intergalactic gas. COS's far-ultraviolet channel has a sensitivity 30 times greater than that of previous spectroscopic instruments for the detection of extremely low light levels. Launch of STS-125 is targeted for Oct. 8. Photo credit: NASA/Jack Pfaller

KSC-08pd2180

NASA Image and Video Library

2008-07-29

CAPE CANAVERAL, Fla. – At NASA's Kennedy Space Center, workers from NASA's Goddard Space Flight Center receive the Cosmic Origins Spectrograph, or COS, secured in its transportation canister, in the airlock of the Payload Hazardous Servicing Facility. The COS will be installed on the Hubble Space Telescope on space shuttle Atlantis' STS-125 mission. COS will be the most sensitive ultraviolet spectrograph ever flown on Hubble and will probe the "cosmic web" - the large-scale structure of the universe whose form is determined by the gravity of dark matter and is traced by galaxies and intergalactic gas. COS's far-ultraviolet channel has a sensitivity 30 times greater than that of previous spectroscopic instruments for the detection of extremely low light levels. Launch of STS-125 is targeted for Oct. 8. Photo credit: NASA/Jack Pfaller

KSC-08pd2183

NASA Image and Video Library

2008-07-29

CAPE CANAVERAL, Fla. – In the airlock of the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center, workers from NASA's Goddard Space Flight Center examine the Cosmic Origins Spectrograph, or COS, after the top from its transportation canister is removed. The COS will be installed on the Hubble Space Telescope on space shuttle Atlantis' STS-125 mission. COS will be the most sensitive ultraviolet spectrograph ever flown on Hubble and will probe the "cosmic web" - the large-scale structure of the universe whose form is determined by the gravity of dark matter and is traced by galaxies and intergalactic gas. COS's far-ultraviolet channel has a sensitivity 30 times greater than that of previous spectroscopic instruments for the detection of extremely low light levels. Launch of STS-125 is targeted for Oct. 8. Photo credit: NASA/Jack Pfaller

Cosmic Acceleration, Dark Energy, and Fundamental Physics

NASA Astrophysics Data System (ADS)

Turner, Michael S.; Huterer, Dragan

2007-11-01

A web of interlocking observations has established that the expansion of the Universe is speeding up and not slowing, revealing the presence of some form of repulsive gravity. Within the context of general relativity the cause of cosmic acceleration is a highly elastic ( p˜-ρ), very smooth form of energy called “dark energy” accounting for about 75% of the Universe. The “simplest” explanation for dark energy is the zero-point energy density associated with the quantum vacuum; however, all estimates for its value are many orders-of-magnitude too large. Other ideas for dark energy include a very light scalar field or a tangled network of topological defects. An alternate explanation invokes gravitational physics beyond general relativity. Observations and experiments underway and more precise cosmological measurements and laboratory experiments planned for the next decade will test whether or not dark energy is the quantum energy of the vacuum or something more exotic, and whether or not general relativity can self consistently explain cosmic acceleration. Dark energy is the most conspicuous example of physics beyond the standard model and perhaps the most profound mystery in all of science.

Constraining the p¯/p ratio in TeV cosmic rays with observations of the Moon shadow by HAWC

NASA Astrophysics Data System (ADS)

Abeysekara, A. U.; Albert, A.; Alfaro, R.; Alvarez, C.; Álvarez, J. D.; Arceo, R.; Arteaga-Velázquez, J. C.; Avila Rojas, D.; Ayala Solares, H. A.; Belmont-Moreno, E.; BenZvi, S. Y.; Braun, J.; Brisbois, C.; Caballero-Mora, K. S.; Capistrán, T.; Carramiñana, A.; Casanova, S.; Castillo, M.; Cotti, U.; Cotzomi, J.; Coutiño de León, S.; De León, C.; De la Fuente, E.; Diaz Hernandez, R.; Dichiara, S.; Dingus, B. L.; DuVernois, M. A.; Ellsworth, R. W.; Engel, K.; Enríquez-Rivera, O.; Fleischhack, H.; Fraija, N.; Galván-Gámez, A.; García-González, J. A.; González Muñoz, A.; González, M. M.; Hampel-Arias, Z.; Harding, J. P.; Hernandez, S.; Hona, B.; Hueyotl-Zahuantitla, F.; Hui, C. M.; Hüntemeyer, P.; Iriarte, A.; Jardin-Blicq, A.; Joshi, V.; Kaufmann, S.; Lara, A.; Lee, W. H.; León Vargas, H.; Linnemann, J. T.; Longinotti, A. L.; Luis-Raya, G.; Luna-García, R.; López-Coto, R.; Malone, K.; Marinelli, S. S.; Martinez, O.; Martinez-Castellanos, I.; Martínez-Castro, J.; Martínez-Huerta, H.; Matthews, J. A.; Miranda-Romagnoli, P.; Moreno, E.; Mostafá, M.; Nellen, L.; Newbold, M.; Nisa, M. U.; Noriega-Papaqui, R.; Pelayo, R.; Pretz, J.; Pérez-Pérez, E. G.; Ren, Z.; Rho, C. D.; Rivière, C.; Rosa-González, D.; Rosenberg, M.; Ruiz-Velasco, E.; Salesa Greus, F.; Sandoval, A.; Schneider, M.; Schoorlemmer, H.; Seglar Arroyo, M.; Sinnis, G.; Smith, A. J.; Springer, R. W.; Surajbali, P.; Taboada, I.; Tibolla, O.; Torres, I.; Villaseñor, L.; Weisgarber, T.; Westerhoff, S.; Wood, J.; Yapici, T.; Yodh, G. B.; Zepeda, A.; Zhou, H.; HAWC Collaboration

2018-05-01

An indirect measurement of the antiproton flux in cosmic rays is possible as the particles undergo deflection by the geomagnetic field. This effect can be measured by studying the deficit in the flux, or shadow, created by the Moon as it absorbs cosmic rays that are headed toward the Earth. The shadow is displaced from the actual position of the Moon due to geomagnetic deflection, which is a function of the energy and charge of the cosmic rays. The displacement provides a natural tool for momentum/charge discrimination that can be used to study the composition of cosmic rays. Using 33 months of data comprising more than 80 billion cosmic rays measured by the High Altitude Water Cherenkov observatory, we have analyzed the Moon shadow to search for TeV antiprotons in cosmic rays. We present our first upper limits on the p ¯/p fraction, which in the absence of any direct measurements provide the tightest available constraints of ˜1 % on the antiproton fraction for energies between 1 and 10 TeV.

Biocore experiment. [Apollo 17 mission

NASA Technical Reports Server (NTRS)

Bailey, O. T.; Benton, E. V.; Cruty, M. R.; Harrison, G. A.; Haymaker, W.; Humason, G.; Leon, H. A.; Lindberg, R. L.; Look, B. C.; Lushbaugh, C. C.

1973-01-01

The Apollo 17 biological cosmic ray experiment to determine the effect of heavy cosmic ray particles on the brain and eyes is reported. The pocket mouse was selected as the biological specimen for the experiment. The radiation monitors, animal autopsy and animal processing are described, and the radiation effects on the scalp, retina, and viscera are analyzed.

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

Ciuca, Razvan; Hernández, Oscar F., E-mail: razvan.ciuca@mail.mcgill.ca, E-mail: oscarh@physics.mcgill.ca

There exists various proposals to detect cosmic strings from Cosmic Microwave Background (CMB) or 21 cm temperature maps. Current proposals do not aim to find the location of strings on sky maps, all of these approaches can be thought of as a statistic on a sky map. We propose a Bayesian interpretation of cosmic string detection and within that framework, we derive a connection between estimates of cosmic string locations and cosmic string tension G μ. We use this Bayesian framework to develop a machine learning framework for detecting strings from sky maps and outline how to implement this frameworkmore » with neural networks. The neural network we trained was able to detect and locate cosmic strings on noiseless CMB temperature map down to a string tension of G μ=5 ×10{sup −9} and when analyzing a CMB temperature map that does not contain strings, the neural network gives a 0.95 probability that G μ≤2.3×10{sup −9}.« less

Cosmic ray neutrino tests for heavier weak bosons and cosmic antimatter

NASA Technical Reports Server (NTRS)

Brown, R. W.; Stecker, F. W.

1981-01-01

A program for using high energy neutrino astronomy with large neutrino detectors to directly test for the existence of heavier weak intermediate vector bosons (ivb) and cosmic antimatter is described. Such observations can provide a direct test of baryon symmetric cosmologies. Changes in the total cross section for nu(N) yields mu(X) due to additional propagators are discussed and higher mass resonances in the annihilation channel bar-nu sub e e(-) yields X are analyzed. The annihilation channel is instrumental in the search for antimatter, partcularly if heavier IVB's exist.

Cosmic dust-ion-acoustic waves, spherical modified Kadomtsev-Petviashvili model, and symbolic computation

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

Gao Yitian; Tian Bo; State Key Laboratory of Software Development Environment, Beijing University of Aeronautics and Astronautics, Beijing 100083

2006-11-15

The spherical modified Kadomtsev-Petviashvili (smKP) model is hereby derived with symbolic computation for the dust-ion-acoustic waves with zenith-angle perturbation in a cosmic dusty plasma. Formation and properties of both dark and bright smKP nebulons are obtained and discussed. The relevance of those smKP nebulons to the supernova shells and Saturn's F-ring is pointed out, and possibly observable nebulonic effects for the future cosmic plasma experiments are proposed. The difference of the smKP nebulons from other types of nebulons is also analyzed.

Cosmic censorship of rotating Anti-de Sitter black hole

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

Gwak, Bogeun; Lee, Bum-Hoon, E-mail: rasenis@sogang.ac.kr, E-mail: bhl@sogang.ac.kr

2016-02-01

We test the validity of cosmic censorship in the rotating anti-de Sitter black hole. For this purpose, we investigate whether the extremal black hole can be overspun by the particle absorption. The particle absorption will change the mass and angular momentum of the black hole, which is analyzed using the Hamilton-Jacobi equations consistent with the laws of thermodynamics. We have found that the mass of the extremal black hole increases more than the angular momentum. Therefore, the outer horizon of the black hole still exists, and cosmic censorship is valid.

The Spin and Orientation of Dark Matter Halos Within Cosmic Filaments

NASA Astrophysics Data System (ADS)

Zhang, Youcai; Yang, Xiaohu; Faltenbacher, Andreas; Springel, Volker; Lin, Weipeng; Wang, Huiyuan

2009-11-01

Clusters, filaments, sheets, and voids are the building blocks of the cosmic web. Forming dark matter halos respond to these different large-scale environments, and this in turn affects the properties of galaxies hosted by the halos. It is therefore important to understand the systematic correlations of halo properties with the morphology of the cosmic web, as this informs both about galaxy formation physics and possible systematics of weak lensing studies. In this study, we present and compare two distinct algorithms for finding cosmic filaments and sheets, a task which is far less well established than the identification of dark matter halos or voids. One method is based on the smoothed dark matter density field and the other uses the halo distributions directly. We apply both techniques to one high-resolution N-body simulation and reconstruct the filamentary/sheet like network of the dark matter density field. We focus on investigating the properties of the dark matter halos inside these structures, in particular, on the directions of their spins and the orientation of their shapes with respect to the directions of the filaments and sheets. We find that both the spin and the major axes of filament halos with masses lsim1013 h -1 M sun are preferentially aligned with the direction of the filaments. The spins and major axes of halos in sheets tend to lie parallel to the sheets. There is an opposite mass dependence of the alignment strength for the spin (negative) and major (positive) axes, i.e. with increasing halo mass the major axis tends to be more strongly aligned with the direction of the filament, whereas the alignment between halo spin and filament becomes weaker with increasing halo mass. The alignment strength as a function of the distance to the most massive node halo indicates that there is a transit large-scale environment impact: from the two-dimensional collapse phase of the filament to the three-dimensional collapse phase of the cluster/node halo at small separation. Overall, the two algorithms for filament/sheet identification investigated here agree well with each other. The method based on halos alone can be easily adapted for use with observational data sets.

Comparison of COSMIC RO Data with European Digisondes and GPS TEC measurements

NASA Astrophysics Data System (ADS)

Zakharenkova, Irina; Krypiak-Gregorczyk, Anna; Shagimuratov, Irk; Krankowski, Andrzej; Lagovsky, Anatoly

FormoSat-3/COSMIC now provides unprecedented global coverage of GPS occultations mea-surements, each of which yields the ionosphere electron density information with high vertical resolution. However systematic validation work is still needed before using the powerful RO technique for sounding the ionosphere on a routine basis. In the given study electron density profiles retrieved from the Formosat-3/COSMIC RO measurements were compared with differ-ent kinds of ground-based observations. We used the ionospheric data recorded by European digisondes of DIAS network (Rome, Ebro, Arenosillo, Athens, Chilton, Pruhonice and Julius-ruh) for temporal interval of 2007-2009 and compare these ground measured data with the GPS COSMIC RO ionospheric profiles. It was revealed that in general the form of COSMIC profile in the bottom side is in a good agreement with ionosonde profiles, the heights of the peak density value are also good comparable. Special attention was focused to the question of the topside part of electron density profile. Practically for all analyzed cases there are observed the understated values of electron density in the topside part of the ionosonde profiles in compare with RO profiles. As the topside ionosonde profile is obtained by fitting a model to the peak electron density value, the COSMIC radio occultation measurements can make an important contribution to the investigation of the topside part of the ionosphere. In order to assess the ac-curacy of the COSMIC ionospheric electron density retrievals, coincidences of ionosonde data with COSMIC NmF2 values have been examined. NmF2 was calculated from the observed critical plasma frequency foF2 of the F2 layer. Values of foF2 have been scaled manually from ionograms for all considered time-location cases to avoid the evident risks related with using of the autoscaled data. The created scatter plots show a high degree of correlation between two independent estimates of NmF2. Also it was analyzed the variation of NmF2 for the considered seasons depending on day-time and night-time conditions. Also it was analyzed the total elec-tron content values calculated for the nearest ground-based GPS stations located in European region. To compare GPS TEC with RO and ionosondes' data these profiles were integrated. In general bottom parts of COSMIC and ionosondes' data are in a rather good agreement while the topside can be varied greatly that is the evidence of difference in the topside parts of these profiles. GPS TEC values are greater than COSMIC and ionosondes' data as TEC contains IEC and PEC. This procedure can be useful to estimate the impact of PEC into TEC. Results of the given comparisons can be important to validate the reliability of the COSMIC iono-spheric observations using the RO technique. We acknowledge the Taiwan's National Space Organization (NSPO) and the University Corporation for Atmospheric Research (UCAR) for providing the COSMIC Data. We are grateful to European Digital Upper Atmosphere Server (DIAS) for providing the ionosondes' products and to International GNSS Service (IGS) for GPS Data.

Observations of a nearby filament of galaxy clusters with the Sardinia Radio Telescope

NASA Astrophysics Data System (ADS)

Vacca, Valentina; Murgia, M.; Loi, F. Govoni F.; Vazza, F.; Finoguenov, A.; Carretti, E.; Feretti, L.; Giovannini, G.; Concu, R.; Melis, A.; Gheller, C.; Paladino, R.; Poppi, S.; Valente, G.; Bernardi, G.; Boschin, W.; Brienza, M.; Clarke, T. E.; Colafrancesco, S.; Enßlin, T.; Ferrari, C.; de Gasperin, F.; Gastaldello, F.; Girardi, M.; Gregorini, L.; Johnston-Hollitt, M.; Junklewitz, H.; Orrù, E.; Parma, P.; Perley, R.; Taylor, G. B.

2018-05-01

We report the detection of diffuse radio emission which might be connected to a large-scale filament of the cosmic web covering a 8° × 8° area in the sky, likely associated with a z≈0.1 over-density traced by nine massive galaxy clusters. In this work, we present radio observations of this region taken with the Sardinia Radio Telescope. Two of the clusters in the field host a powerful radio halo sustained by violent ongoing mergers and provide direct proof of intra-cluster magnetic fields. In order to investigate the presence of large-scale diffuse radio synchrotron emission in and beyond the galaxy clusters in this complex system, we combined the data taken at 1.4 GHz with the Sardinia Radio Telescope with higher resolution data taken with the NRAO VLA Sky Survey. We found 28 candidate new sources with a size larger and X-ray emission fainter than known diffuse large-scale synchrotron cluster sources for a given radio power. This new population is potentially the tip of the iceberg of a class of diffuse large-scale synchrotron sources associated with the filaments of the cosmic web. In addition, we found in the field a candidate new giant radio galaxy.

Search for patterns by combining cosmic-ray energy and arrival directions at the Pierre Auger Observatory.

PubMed

Aab, A; Abreu, P; Aglietta, M; Ahn, E J; Samarai, I Al; Albuquerque, I F M; Allekotte, I; Allen, J; Allison, P; Almela, A; Castillo, J Alvarez; Alvarez-Muñiz, J; Batista, R Alves; Ambrosio, M; Aminaei, A; Anchordoqui, L; Andringa, S; Aramo, C; Aranda, V M; Arqueros, F; Asorey, H; Assis, P; Aublin, J; Ave, M; Avenier, M; Avila, G; Awal, N; Badescu, A M; Barber, K B; Bäuml, J; Baus, C; Beatty, J J; Becker, K H; Bellido, J A; Berat, C; Bertaina, M E; Bertou, X; Biermann, P L; Billoir, P; Blaess, S; Blanco, M; Bleve, C; Blümer, H; Boháčová, M; Boncioli, D; Bonifazi, C; Bonino, R; Borodai, N; Brack, J; Brancus, I; Bridgeman, A; Brogueira, P; Brown, W C; Buchholz, P; Bueno, A; Buitink, S; Buscemi, M; Caballero-Mora, K S; Caccianiga, B; Caccianiga, L; Candusso, M; Caramete, L; Caruso, R; Castellina, A; Cataldi, G; Cazon, L; Cester, R; Chavez, A G; Chiavassa, A; Chinellato, J A; Chudoba, J; Cilmo, M; Clay, R W; Cocciolo, G; Colalillo, R; Coleman, A; Collica, L; Coluccia, M R; Conceição, R; Contreras, F; Cooper, M J; Cordier, A; Coutu, S; Covault, C E; Cronin, J; Curutiu, A; Dallier, R; Daniel, B; Dasso, S; Daumiller, K; Dawson, B R; Almeida, R M de; Domenico, M De; Jong, S J de; Neto, J R T de Mello; Mitri, I De; Oliveira, J de; Souza, V de; Peral, L Del; Deligny, O; Dembinski, H; Dhital, N; Giulio, C Di; Matteo, A Di; Diaz, J C; Castro, M L Díaz; Diogo, F; Dobrigkeit, C; Docters, W; D'Olivo, J C; Dorofeev, A; Hasankiadeh, Q Dorosti; Dova, M T; Ebr, J; Engel, R; Erdmann, M; Erfani, M; Escobar, C O; Espadanal, J; Etchegoyen, A; Luis, P Facal San; Falcke, H; Fang, K; Farrar, G; Fauth, A C; Fazzini, N; Ferguson, A P; Fernandes, M; Fick, B; Figueira, J M; Filevich, A; Filipčič, A; Fox, B D; Fratu, O; Fröhlich, U; Fuchs, B; Fujii, T; Gaior, R; García, B; Roca, S T Garcia; Garcia-Gamez, D; Garcia-Pinto, D; Garilli, G; Bravo, A Gascon; Gate, F; Gemmeke, H; Ghia, P L; Giaccari, U; Giammarchi, M; Giller, M; Glaser, C; Glass, H; Berisso, M Gómez; Vitale, P F Gómez; Gonçalves, P; Gonzalez, J G; González, N; Gookin, B; Gordon, J; Gorgi, A; Gorham, P; Gouffon, P; Grebe, S; Griffith, N; Grillo, A F; Grubb, T D; Guarino, F; Guedes, G P; Hampel, M R; Hansen, P; Harari, D; Harrison, T A; Hartmann, S; Harton, J L; Haungs, A; Hebbeker, T; Heck, D; Heimann, P; Herve, A E; Hill, G C; Hojvat, C; Hollon, N; Holt, E; Homola, P; Hörandel, J R; Horvath, P; Hrabovský, M; Huber, D; Huege, T; Insolia, A; Isar, P G; Jandt, I; Jansen, S; Jarne, C; Josebachuili, M; Kääpä, A; Kambeitz, O; Kampert, K H; Kasper, P; Katkov, I; Kégl, B; Keilhauer, B; Keivani, A; Kemp, E; Kieckhafer, R M; Klages, H O; Kleifges, M; Kleinfeller, J; Krause, R; Krohm, N; Krömer, O; Kruppke-Hansen, D; Kuempel, D; Kunka, N; LaHurd, D; Latronico, L; Lauer, R; Lauscher, M; Lautridou, P; Coz, S Le; Leão, M S A B; Lebrun, D; Lebrun, P; Oliveira, M A Leigui de; Letessier-Selvon, A; Lhenry-Yvon, I; Link, K; López, R; Agüera, A Lopez; Louedec, K; Bahilo, J Lozano; Lu, L; Lucero, A; Ludwig, M; Malacari, M; Maldera, S; Mallamaci, M; Maller, J; Mandat, D; Mantsch, P; Mariazzi, A G; Marin, V; Mariş, I C; Marsella, G; Martello, D; Martin, L; Martinez, H; Bravo, O Martínez; Martraire, D; Meza, J J Masías; Mathes, H J; Mathys, S; Matthews, J; Matthews, J A J; Matthiae, G; Maurel, D; Maurizio, D; Mayotte, E; Mazur, P O; Medina, C; Medina-Tanco, G; Meissner, R; Melissas, M; Melo, D; Menshikov, A; Messina, S; Meyhandan, R; Mićanović, S; Micheletti, M I; Middendorf, L; Minaya, I A; Miramonti, L; Mitrica, B; Molina-Bueno, L; Mollerach, S; Monasor, M; Ragaigne, D Monnier; Montanet, F; Morello, C; Mostafá, M; Moura, C A; Muller, M A; Müller, G; Müller, S; Münchmeyer, M; Mussa, R; Navarra, G; Navas, S; Necesal, P; Nellen, L; Nelles, A; Neuser, J; Nguyen, P; Niechciol, M; Niemietz, L; Niggemann, T; Nitz, D; Nosek, D; Novotny, V; Nožka, L; Ochilo, L; Olinto, A; Oliveira, M; Pacheco, N; Selmi-Dei, D Pakk; Palatka, M; Pallotta, J; Palmieri, N; Papenbreer, P; Parente, G; Parra, A; Paul, T; Pech, M; Pȩkala, J; Pelayo, R; Pepe, I M; Perrone, L; Petermann, E; Peters, C; Petrera, S; Petrov, Y; Phuntsok, J; Piegaia, R; Pierog, T; Pieroni, P; Pimenta, M; Pirronello, V; Platino, M; Plum, M; Porcelli, A; Porowski, C; Prado, R R; Privitera, P; Prouza, M; Purrello, V; Quel, E J; Querchfeld, S; Quinn, S; Rautenberg, J; Ravel, O; Ravignani, D; Revenu, B; Ridky, J; Riggi, S; Risse, M; Ristori, P; Rizi, V; Carvalho, W Rodrigues de; Cabo, I Rodriguez; Fernandez, G Rodriguez; Rojo, J Rodriguez; Rodríguez-Frías, M D; Rogozin, D; Ros, G; Rosado, J; Rossler, T; Roth, M; Roulet, E; Rovero, A C; Saffi, S J; Saftoiu, A; Salamida, F; Salazar, H; Saleh, A; Greus, F Salesa; Salina, G; Sánchez, F; Sanchez-Lucas, P; Santo, C E; Santos, E; Santos, E M; Sarazin, F; Sarkar, B; Sarmento, R; Sato, R; Scharf, N; Scherini, V; Schieler, H; Schiffer, P; Schmidt, D; Schröder, F G; Scholten, O; Schoorlemmer, H; Schovánek, P; Schulz, A; Schulz, J; Schumacher, J; Sciutto, S J; Segreto, A; Settimo, M; Shadkam, A; Shellard, R C; Sidelnik, I; Sigl, G; Sima, O; Kowski, A Śmiał; Šmída, R; Snow, G R; Sommers, P; Sorokin, J; Squartini, R; Srivastava, Y N; Stanič, S; Stapleton, J; Stasielak, J; Stephan, M; Stutz, A; Suarez, F; Suomijärvi, T; Supanitsky, A D; Sutherland, M S; Swain, J; Szadkowski, Z; Szuba, M; Taborda, O A; Tapia, A; Tartare, M; Tepe, A; Theodoro, V M; Timmermans, C; Peixoto, C J Todero; Toma, G; Tomankova, L; Tomé, B; Tonachini, A; Elipe, G Torralba; Machado, D Torres; Travnicek, P; Trovato, E; Tueros, M; Ulrich, R; Unger, M; Urban, M; Galicia, J F Valdés; Valiño, I; Valore, L; Aar, G van; Bodegom, P van; Berg, A M van den; Velzen, S van; Vliet, A van; Varela, E; Vargas Cárdenas, B; Varner, G; Vázquez, J R; Vázquez, R A; Veberič, D; Verzi, V; Vicha, J; Videla, M; Villaseñor, L; Vlcek, B; Vorobiov, S; Wahlberg, H; Wainberg, O; Walz, D; Watson, A A; Weber, M; Weidenhaupt, K; Weindl, A; Werner, F; Widom, A; Wiencke, L; Wilczyńska, B; Wilczyński, H; Will, M; Williams, C; Winchen, T; Wittkowski, D; Wundheiler, B; Wykes, S; Yamamoto, T; Yapici, T; Yuan, G; Yushkov, A; Zamorano, B; Zas, E; Zavrtanik, D; Zavrtanik, M; Zaw, I; Zepeda, A; Zhou, J; Zhu, Y; Silva, M Zimbres; Ziolkowski, M; Zuccarello, F

Energy-dependent patterns in the arrival directions of cosmic rays are searched for using data of the Pierre Auger Observatory. We investigate local regions around the highest-energy cosmic rays with [Formula: see text] eV by analyzing cosmic rays with energies above [Formula: see text] eV arriving within an angular separation of approximately 15[Formula: see text]. We characterize the energy distributions inside these regions by two independent methods, one searching for angular dependence of energy-energy correlations and one searching for collimation of energy along the local system of principal axes of the energy distribution. No significant patterns are found with this analysis. The comparison of these measurements with astrophysical scenarios can therefore be used to obtain constraints on related model parameters such as strength of cosmic-ray deflection and density of point sources.

Supernova Remnant Kes 17: An Efficient Cosmic Ray Accelerator inside a Molecular Cloud

NASA Astrophysics Data System (ADS)

Gelfand, Joseph D.; Castro, Daniel; Slane, Patrick O.; Temim, Tea; Hughes, John P.; Rakowski, Cara

2013-11-01

The supernova remnant Kes 17 (SNR G304.6+0.1) is one of a few but growing number of remnants detected across the electromagnetic spectrum. In this paper, we analyze recent radio, X-ray, and γ-ray observations of this object, determining that efficient cosmic ray acceleration is required to explain its broadband non-thermal spectrum. These observations also suggest that Kes 17 is expanding inside a molecular cloud, though our determination of its age depends on whether thermal conduction or clump evaporation is primarily responsible for its center-filled thermal X-ray morphology. Evidence for efficient cosmic ray acceleration in Kes 17 supports recent theoretical work concluding that the strong magnetic field, turbulence, and clumpy nature of molecular clouds enhance cosmic ray production in supernova remnants. While additional observations are needed to confirm this interpretation, further study of Kes 17 is important for understanding how cosmic rays are accelerated in supernova remnants.

Search for patterns by combining cosmic-ray energy and arrival directions at the Pierre Auger Observatory

DOE PAGES

Aab, Alexander

2015-06-20

Energy-dependent patterns in the arrival directions of cosmic rays are searched for using data of the Pierre Auger Observatory. We investigate local regions around the highest-energy cosmic rays with E ≥ 6×10 19 eV by analyzing cosmic rays with energies above E ≥ 5×10 18 eV arriving within an angular separation of approximately 15°. We characterize the energy distributions inside these regions by two independent methods, one searching for angular dependence of energy-energy correlations and one searching for collimation of energy along the local system of principal axes of the energy distribution. No significant patterns are found with this analysis.more » As a result, the comparison of these measurements with astrophysical scenarios can therefore be used to obtain constraints on related model parameters such as strength of cosmic-ray deflection and density of point sources.« less

On the motion of a quantum particle in the spinning cosmic string space–time

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

Hassanabadi, H., E-mail: h.hasanabadi@shahroodut.ac.ir; Afshardoost, A.; Zarrinkamar, S.

2015-05-15

We analyze the energy spectrum and the wave function of a particle subjected to magnetic field in the spinning cosmic string space–time and investigate the influence of the spinning reference frame and topological defect on the system. To do this we solve Schrödinger equation in the spinning cosmic string background. In our work, instead of using an approximation in the calculations, we use the quasi-exact ansatz approach which gives the exact solutions for some primary levels. - Highlights: • Solving the Schrödinger equation in the spinning cosmic string space time. • Proposing a quasi-exact analytical solution to the general formmore » of the corresponding equation. • Generalizing the previous works.« less

Klein-Gordon oscillator with position-dependent mass in the rotating cosmic string spacetime

NASA Astrophysics Data System (ADS)

Wang, Bing-Qian; Long, Zheng-Wen; Long, Chao-Yun; Wu, Shu-Rui

2018-02-01

A spinless particle coupled covariantly to a uniform magnetic field parallel to the string in the background of the rotating cosmic string is studied. The energy levels of the electrically charged particle subject to the Klein-Gordon oscillator are analyzed. Afterwards, we consider the case of the position-dependent mass and show how these energy levels depend on the parameters in the problem. Remarkably, it shows that for the special case, the Klein-Gordon oscillator coupled covariantly to a homogeneous magnetic field with the position-dependent mass in the rotating cosmic string background has the similar behaviors to the Klein-Gordon equation with a Coulomb-type configuration in a rotating cosmic string background in the presence of an external magnetic field.

Examining the cosmic acceleration with the latest Union2 supernova data

NASA Astrophysics Data System (ADS)

Li, Zhengxiang; Wu, Puxun; Yu, Hongwei

2011-01-01

In this Letter, by reconstructing the Om diagnostic and the deceleration parameter q from the latest Union2 Type Ia Supernova sample with and without the systematic error along with the baryon acoustic oscillation (BAO) and the cosmic microwave background (CMB), we study the cosmic expanding history, using the Chevallier-Polarski-Linder (CPL) parametrization. We obtain that Union2+BAO favor an expansion with a decreasing of the acceleration at z<0.3. However, once the CMB data is added in the analysis, the cosmic acceleration is found to be still increasing, indicating a tension between low redshift data and high redshift. In order to reduce this tension significantly, two different methods are considered and thus two different subsamples of Union2 are selected. We then find that two different subsamples+BAO+CMB give completely different results on the cosmic expanding history when the systematic error is ignored, with one suggesting a decreasing cosmic acceleration, the other just the opposite, although both of them alone with BAO support that the cosmic acceleration is slowing down. However, once the systematic error is considered, two different subsamples of Union2 along with BAO and CMB all favor an increasing of the present cosmic acceleration. Therefore a clear-cut answer on whether the cosmic acceleration is slowing down calls for more consistent data and more reliable methods to analyze them.

KSC-08pd2191

NASA Image and Video Library

2008-07-29

CAPE CANAVERAL, Fla. – At NASA's Kennedy Space Center, workers from NASA's Goddard Space Flight Center roll the Cosmic Origins Spectrograph, or COS, into position in the clean room of the Payload Hazardous Servicing Facility for instrument testing and integration with the Flight Support System carrier. The COS will be installed on the Hubble Space Telescope on space shuttle Atlantis' STS-125 mission. COS will be the most sensitive ultraviolet spectrograph ever flown on Hubble and will probe the "cosmic web" - the large-scale structure of the universe whose form is determined by the gravity of dark matter and is traced by galaxies and intergalactic gas. COS's far-ultraviolet channel has a sensitivity 30 times greater than that of previous spectroscopic instruments for the detection of extremely low light levels. Launch of STS-125 is targeted for Oct. 8. Photo credit: NASA/Jack Pfaller

KSC-08pd2186

NASA Image and Video Library

2008-07-29

CAPE CANAVERAL, Fla. – In the airlock of the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center, workers from NASA's Goddard Space Flight Center lift the Cosmic Origins Spectrograph, or COS, from its transportation canister onto a dolly for its move into the clean room. The COS will be installed on the Hubble Space Telescope on space shuttle Atlantis' STS-125 mission. COS will be the most sensitive ultraviolet spectrograph ever flown on Hubble and will probe the "cosmic web" - the large-scale structure of the universe whose form is determined by the gravity of dark matter and is traced by galaxies and intergalactic gas. COS's far-ultraviolet channel has a sensitivity 30 times greater than that of previous spectroscopic instruments for the detection of extremely low light levels. Launch of STS-125 is targeted for Oct. 8. Photo credit: NASA/Jack Pfaller

KSC-08pd2188

NASA Image and Video Library

2008-07-29

CAPE CANAVERAL, Fla. – At NASA's Kennedy Space Center, workers from NASA's Goddard Space Flight Center roll the Cosmic Origins Spectrograph, or COS, from the airlock, where it was removed from the shipping container, to the clean room of the Payload Hazardous Servicing Facility. The COS will be installed on the Hubble Space Telescope on space shuttle Atlantis' STS-125 mission. COS will be the most sensitive ultraviolet spectrograph ever flown on Hubble and will probe the "cosmic web" - the large-scale structure of the universe whose form is determined by the gravity of dark matter and is traced by galaxies and intergalactic gas. COS's far-ultraviolet channel has a sensitivity 30 times greater than that of previous spectroscopic instruments for the detection of extremely low light levels. Launch of STS-125 is targeted for Oct. 8. Photo credit: NASA/Jack Pfaller

KSC-08pd2187

NASA Image and Video Library

2008-07-29

CAPE CANAVERAL, Fla. – In the airlock of the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center, workers from NASA's Goddard Space Flight Center lower the Cosmic Origins Spectrograph, or COS, onto a dolly for its move into the clean room. The COS will be installed on the Hubble Space Telescope on space shuttle Atlantis' STS-125 mission. COS will be the most sensitive ultraviolet spectrograph ever flown on Hubble and will probe the "cosmic web" - the large-scale structure of the universe whose form is determined by the gravity of dark matter and is traced by galaxies and intergalactic gas. COS's far-ultraviolet channel has a sensitivity 30 times greater than that of previous spectroscopic instruments for the detection of extremely low light levels. Launch of STS-125 is targeted for Oct. 8. Photo credit: NASA/Jack Pfaller

KSC-08pd2192

NASA Image and Video Library

2008-07-29

CAPE CANAVERAL, Fla. – At NASA's Kennedy Space Center, workers from NASA's Goddard Space Flight Center prepare the Cosmic Origins Spectrograph, or COS, for instrument testing and integration with the Flight Support System carrier in the clean room of the Payload Hazardous Servicing Facility. The COS will be installed on the Hubble Space Telescope on space shuttle Atlantis' STS-125 mission. COS will be the most sensitive ultraviolet spectrograph ever flown on Hubble and will probe the "cosmic web" - the large-scale structure of the universe whose form is determined by the gravity of dark matter and is traced by galaxies and intergalactic gas. COS's far-ultraviolet channel has a sensitivity 30 times greater than that of previous spectroscopic instruments for the detection of extremely low light levels. Launch of STS-125 is targeted for Oct. 8. Photo credit: NASA/Jack Pfaller

Non-Abelian cosmic string in the Starobinsky model of gravity

NASA Astrophysics Data System (ADS)

Morais Graça, J. P.; de Pádua Santos, A.; Bezerra de Mello, Eugênio R.; Bezerra, V. B.

In this paper, we analyze numerically the behavior of the solutions corresponding to a non-Abelian cosmic string in the framework of the Starobinsky model, i.e. where f(R) = R + ζR2. We perform the calculations for both an asymptotically flat and asymptotically (anti)-de Sitter spacetimes. We found that the angular deficit generated by the string decreases as the parameter ζ increases, in the case of a null cosmological constant. For a positive cosmological constant, we found that the cosmic horizon is affected in a nontrivial way by the parameter ζ.

Temporal signatures of the Cherenkov light induced by extensive air showers of cosmic rays detected with the Yakutsk array

NASA Astrophysics Data System (ADS)

Ivanov, A. A.; Timofeev, L. V.

2016-05-01

We analyze temporal characteristics of signals from the wide field-of-view (WFOV) Cherenkov telescope (CT) detecting extensive air showers (EAS) of cosmic rays (CRs) in coincidence with surface detectors of the Yakutsk array. Our aim is to reveal causal relationships between measured characteristics and physical properties of EAS.

Cosmic ray topography

NASA Astrophysics Data System (ADS)

Bressler, Matthew; Goodwin, Lydia; Kryemadhi, Abaz

2017-11-01

Cosmic ray muons are produced when high energy particles interact with nuclei in Earth's atmosphere. Muons make up the majority of charged particles that reach sea level and are the only particles (apart from neutrinos) that can penetrate to significant depths underground. The muon flux underground decreases approximately exponentially as a function of depth. We use a cosmic ray detector developed by the QuarkNet Program at Fermi National Laboratory to map the topography of the mountain above an abandoned Pennsylvania Turnpike tunnel by analyzing muon flux at different rock overburdens. Cosmic ray muons have been used in this capacity before to search for hidden chambers in pyramids and for mapping volcanoes. This study provides a unique field experience to learn about particle physics and particle detectors, which could be of interest to students and teachers in physics.

The emergence of the ecological mind in Hua-Yen/Kegon Buddhism and Jungian psychology.

PubMed

Cambray, Joe

2017-02-01

The complexity associated with deep interconnectedness in nature is beginning to be articulated and elaborated in the field of ecological studies. While some parallels to the psyche have been made and the field of Eco-psychology has been developing, Jung's explicit contribution by way of the image of rhizomes has not been considered in detail. Philosopher Gilles Deleuze acknowledges borrowing the term from Jung, though he disagreed with Jung's Empedoclean use of the term. The paper presents some fundamental properties of rhizomes along with contemporary scientific research on mycorrhizal (fungal) networks. Comparisons are made, first with classical symbolic forms, demonstrating some overlap but also some differences. Then comparison of rhizomal networks is made to those found both in mammalian brains and in recent images of the 'cosmic web'. While no hard conclusions can be drawn from these images, their remarkable similarities are suggestive of a need to reconsider what is meant by 'intelligence'. The cosmic web is one of the largest structures in the known universe (clusters of galaxies which form into filaments and walls) with empty spaces in between. Exploration of the structure of this web leads to a discussion of dark matter and dark energy, current hot topics in science, probing into the mysteries of our 'Big-Bang' cosmology. An additional comparison of the emerging image of the universe as a whole with the ancient Chinese Buddhist cosmological vision from the Hua-Yen School (Kegon in Japan) again reveals profound parallels. The potential convergence of aspects of subjective, or meditative, explorations with objective scientific constructions is striking and offers links between East and West, as well as potential confirmation of the objective aspects of empathy. © 2017, The Society of Analytical Psychology.

The Formation of Solid Particles from their Gas-Phase Molecular Precursors in Cosmic Environments with NASA Ames' COSmIC Facility

NASA Technical Reports Server (NTRS)

Salama, Farid

2014-01-01

We present and discuss the unique characteristics and capabilities of the laboratory facility, COSmIC, that was developed at NASA Ames to generate, process and analyze interstellar, circumstellar and planetary analogs in the laboratory. COSmIC stands for Cosmic Simulation Chamber and is dedicated to the study of molecules and ions under the low temperature and high vacuum conditions that are required to simulate interstellar, circumstellar and planetary physical environments in space. COSmIC integrates a variety of state-of-the-art instruments that allow forming, processing and monitoring simulated space conditions for planetary, circumstellar and interstellar materials in the laboratory. COSmIC is composed of a Pulsed Discharge Nozzle (PDN) expansion that generates a free jet supersonic expansion coupled to two ultrahigh-sensitivity, complementary in situ diagnostics: a Cavity Ring Down Spectroscopy (CRDS) system for photonic detection and a Reflectron Time-Of-Flight Mass Spectrometer (ReTOF-MS) for mass detection. Recent, unique, laboratory astrophysics results that were obtained using the capabilities of COSmIC will be discussed, in particular the progress that have been achieved in monitoring in the laboratory the formation of solid gains from their gas-phase molecular precursors in environments as varied as stellar/circumstellar outflow and planetary atmospheres. Plans for future, next generation, laboratory experiments on cosmic molecules and grains in the growing field of laboratory astrophysics will also be addressed as well as the implications of these studies for current and upcoming space missions.

Cosmic transcendence, loneliness, and exchange of emotional support with adult children: a study among older parents in The Netherlands.

PubMed

Sadler, E A; Braam, A W; Broese van Groenou, M I; Deeg, D J H; van der Geest, S

2006-09-01

Gerotranscendence defines a shift in meta-perspective from earlier materialistic and pragmatic concerns, toward more cosmic and transcendent ones in later life. Population-based studies that have empirically examined this concept using Tornstam's gerotranscendence scale, highlight cosmic transcendence as a core component, which includes a sense of belongingness with past and future generations. Such generative concerns may increase expectations regarding the quality of the bond with one's children in later life. This study examined whether the association between emotional support exchanged with children and feelings of loneliness later in life varied by the degree of cosmic transcendence of the older parent. Data from 1,845 older parents participating in a population-based study living in The Netherlands were analyzed from the 1995/1996 cycle of the Longitudinal Aging Study Amsterdam. Interviews included self-report measures of cosmic transcendence, loneliness, emotional support exchanged with children, health indicators, and marital status. Results indicated that a negative association between loneliness and level of emotional support exchanged with children was more pronounced among older parents with higher cosmic transcendence scores, in particular among the married. It is argued that cosmic transcendence reflects a sense of generativity and an increased emotional dependency on children in later life. Under favorable social conditions (supportive relationships with children and being married) cosmic transcendent views had a positive impact on social well-being in later life. When children no longer met emotional needs of older parents, cosmic transcendence increased feelings of loneliness.

The Cosmic Dust Analyzer for Cassini

NASA Technical Reports Server (NTRS)

Bradley, James G.; Gruen, Eberhard; Srama, Ralf

1996-01-01

The Cosmic Dust Analyzer (CDA) is designed to characterize the dust environment in interplanetary space, in the Jovian and in the Saturnian systems. The instrument consists of two major components, the Dust Analyzer (DA) and the High Rate Detector (HRD). The DA has a large aperture to provide a large cross section for detection in low flux environments. The DA has the capability of determining dust particle mass, velocity, flight direction, charge, and chemical composition. The chemical composition is determined by the Chemical Analyzer system based on a time-of-flight mass spectrometer. The DA is capable of making full measurements up to one impact/second. The HRD contains two smaller PVDF detectors and electronics designed to characterize dust particle masses at impact rates up to 10(exp 4) impacts/second. These high impact rates are expected during Saturn ring, plane crossings.

Neutron monitors and muon detectors for solar modulation studies: 2. ϕ time series

NASA Astrophysics Data System (ADS)

Ghelfi, A.; Maurin, D.; Cheminet, A.; Derome, L.; Hubert, G.; Melot, F.

2017-08-01

The level of solar modulation at different times (related to the solar activity) is a central question of solar and galactic cosmic-ray physics. In the first paper of this series, we have established a correspondence between the uncertainties on ground-based detectors count rates and the parameter ϕ (modulation level in the force-field approximation) reconstructed from these count rates. In this second paper, we detail a procedure to obtain a reference ϕ time series from neutron monitor data. We show that we can have an unbiased and accurate ϕ reconstruction (Δϕ / ϕ ≃ 10 %). We also discuss the potential of Bonner spheres spectrometers and muon detectors to provide ϕ time series. Two by-products of this calculation are updated ϕ values for the cosmic-ray database and a web interface to retrieve and plot ϕ from the 50's to today (http://lpsc.in2p3.fr/crdb).

The Hubble Space Telescope: UV, Visible, and Near-Infrared Pursuits

NASA Technical Reports Server (NTRS)

Wiseman, Jennifer

2010-01-01

The Hubble Space Telescope continues to push the limits on world-class astrophysics. Cameras including the Advanced Camera for Surveys and the new panchromatic Wide Field Camera 3 which was installed nu last year's successful servicing mission S2N4,o{fer imaging from near-infrared through ultraviolet wavelengths. Spectroscopic studies of sources from black holes to exoplanet atmospheres are making great advances through the versatile use of STIS, the Space Telescope Imaging Spectrograph. The new Cosmic Origins Spectrograph, also installed last year, is the most sensitive UV spectrograph to fly io space and is uniquely suited to address particular scientific questions on galaxy halos, the intergalactic medium, and the cosmic web. With these outstanding capabilities on HST come complex needs for laboratory astrophysics support including atomic and line identification data. I will provide an overview of Hubble's current capabilities and the scientific programs and goals that particularly benefit from the studies of laboratory astrophysics.

KSC-08pd2321

NASA Image and Video Library

2008-08-06

CAPE CANAVERAL, Fla. –In the clean room of the Payload Hazardous Processing Facility at NASA's Kennedy Space Center, a worker from NASA's Goddard Space Flight Center uses black light inspection for a thorough cleaning of the Cosmic Origins Spectrograph, or COS. Black light inspection uses UVA fluorescence to detect possible particulate microcontamination, minute cracks or fluid leaks. The COS will be installed on the Hubble Space Telescope on space shuttle Atlantis' STS-125 mission. COS will be the most sensitive ultraviolet spectrograph ever flown on Hubble and will probe the "cosmic web" - the large-scale structure of the universe whose form is determined by the gravity of dark matter and is traced by galaxies and intergalactic gas. The COS far-ultraviolet channel has a sensitivity 30 times greater than that of previous spectroscopic instruments for the detection of extremely low light levels. Launch of Atlantis on the STS-125 mission is targeted for Oct. 8. Photo credit: NASA/Kim Shiflett

KSC-08pd2333

NASA Image and Video Library

2008-08-07

CAPE CANAVERAL, Fla. – In the clean room of the Payload Hazardous Processing Facility at NASA's Kennedy Space Center, an overhead crane moves the Cosmic Origins Spectrograph, or COS, toward a protective enclosure on the Orbital Replacement Unit Carrier, part of the payload for the fifth and final Hubble servicing mission, STS-125. Other payloads include the Flight Support System, the Super Lightweight Interchangeable Carrier and the Multi-Use Lightweight Equipment, or MULE, carrier. COS will be the most sensitive ultraviolet spectrograph ever flown on Hubble and will probe the "cosmic web" - the large-scale structure of the universe whose form is determined by the gravity of dark matter and is traced by galaxies and intergalactic gas. The COS far-ultraviolet channel has a sensitivity 30 times greater than that of previous spectroscopic instruments for the detection of extremely low light levels. Launch of Atlantis on the STS-125 mission is targeted for Oct. 8. Photo credit: NASA/Kim Shiflett

KSC-08pd2336

NASA Image and Video Library

2008-08-07

CAPE CANAVERAL, Fla. – In the clean room of the Payload Hazardous Processing Facility at NASA's Kennedy Space Center, an overhead crane lowers the Cosmic Origins Spectrograph, or COS, toward a protective enclosure on the Orbital Replacement Unit Carrier, part of the payload for the fifth and final Hubble servicing mission, STS-125. Other payloads include the Flight Support System, the Super Lightweight Interchangeable Carrier and the Multi-Use Lightweight Equipment, or MULE, carrier. COS will be the most sensitive ultraviolet spectrograph ever flown on Hubble and will probe the "cosmic web" - the large-scale structure of the universe whose form is determined by the gravity of dark matter and is traced by galaxies and intergalactic gas. The COS far-ultraviolet channel has a sensitivity 30 times greater than that of previous spectroscopic instruments for the detection of extremely low light levels. Launch of Atlantis on the STS-125 mission is targeted for Oct. 8. Photo credit: NASA/Kim Shiflett

KSC-08pd2325

NASA Image and Video Library

2008-08-06

CAPE CANAVERAL, Fla. – In the clean room of the Payload Hazardous Processing Facility at NASA's Kennedy Space Center, a worker from NASA's Goddard Space Flight Center uses black light inspection for a thorough cleaning of the Cosmic Origins Spectrograph, or COS. Black light inspection uses UVA fluorescence to detect possible particulate microcontamination, minute cracks or fluid leaks. The COS will be installed on the Hubble Space Telescope on space shuttle Atlantis' STS-125 mission. COS will be the most sensitive ultraviolet spectrograph ever flown on Hubble and will probe the "cosmic web" - the large-scale structure of the universe whose form is determined by the gravity of dark matter and is traced by galaxies and intergalactic gas. The COS far-ultraviolet channel has a sensitivity 30 times greater than that of previous spectroscopic instruments for the detection of extremely low light levels. Launch of Atlantis on the STS-125 mission is targeted for Oct. 8. Photo credit: NASA/Kim Shiflett

KSC-08pd2332

NASA Image and Video Library

2008-08-07

CAPE CANAVERAL, Fla. – In the clean room of the Payload Hazardous Processing Facility at NASA's Kennedy Space Center, an overhead crane moves the Cosmic Origins Spectrograph, or COS, toward a protective enclosure on the Orbital Replacement Unit Carrier, part of the payload for the fifth and final Hubble servicing mission, STS-125. Other payloads include the Flight Support System, the Super Lightweight Interchangeable Carrier and the Multi-Use Lightweight Equipment, or MULE, carrier. COS will be the most sensitive ultraviolet spectrograph ever flown on Hubble and will probe the "cosmic web" - the large-scale structure of the universe whose form is determined by the gravity of dark matter and is traced by galaxies and intergalactic gas. The COS far-ultraviolet channel has a sensitivity 30 times greater than that of previous spectroscopic instruments for the detection of extremely low light levels. Launch of Atlantis on the STS-125 mission is targeted for Oct. 8. Photo credit: NASA/Kim Shiflett

KSC-08pd2324

NASA Image and Video Library

2008-08-06

CAPE CANAVERAL, Fla. – In the clean room of the Payload Hazardous Processing Facility at NASA's Kennedy Space Center, a worker from NASA's Goddard Space Flight Center uses black light inspection for a thorough cleaning of the Cosmic Origins Spectrograph, or COS. Black light inspection uses UVA fluorescence to detect possible particulate microcontamination, minute cracks or fluid leaks. The COS will be installed on the Hubble Space Telescope on space shuttle Atlantis' STS-125 mission. COS will be the most sensitive ultraviolet spectrograph ever flown on Hubble and will probe the "cosmic web" - the large-scale structure of the universe whose form is determined by the gravity of dark matter and is traced by galaxies and intergalactic gas. The COS far-ultraviolet channel has a sensitivity 30 times greater than that of previous spectroscopic instruments for the detection of extremely low light levels. Launch of Atlantis on the STS-125 mission is targeted for Oct. 8. Photo credit: NASA/Kim Shiflett

KSC-08pd2334

NASA Image and Video Library

2008-08-07

CAPE CANAVERAL, Fla. – In the clean room of the Payload Hazardous Processing Facility at NASA's Kennedy Space Center, an overhead crane lowers the Cosmic Origins Spectrograph, or COS, toward a protective enclosure on the Orbital Replacement Unit Carrier, part of the payload for the fifth and final Hubble servicing mission, STS-125. Other payloads include the Flight Support System, the Super Lightweight Interchangeable Carrier and the Multi-Use Lightweight Equipment, or MULE, carrier. COS will be the most sensitive ultraviolet spectrograph ever flown on Hubble and will probe the "cosmic web" - the large-scale structure of the universe whose form is determined by the gravity of dark matter and is traced by galaxies and intergalactic gas. The COS far-ultraviolet channel has a sensitivity 30 times greater than that of previous spectroscopic instruments for the detection of extremely low light levels. Launch of Atlantis on the STS-125 mission is targeted for Oct. 8. Photo credit: NASA/Kim Shiflett

KSC-08pd2320

NASA Image and Video Library

2008-08-06

CAPE CANAVERAL, Fla. –The outside of the Cosmic Origins Spectrograph, or COS, is seen before black light inspection in the clean room of the Payload Hazardous Processing Facility at NASA's Kennedy Space Center. Black light inspection uses UVA fluorescence to detect possible particulate microcontamination, minute cracks or fluid leaks. The COS will be installed on the Hubble Space Telescope on space shuttle Atlantis' STS-125 mission. COS will be the most sensitive ultraviolet spectrograph ever flown on Hubble and will probe the "cosmic web" - the large-scale structure of the universe whose form is determined by the gravity of dark matter and is traced by galaxies and intergalactic gas. The COS far-ultraviolet channel has a sensitivity 30 times greater than that of previous spectroscopic instruments for the detection of extremely low light levels. Launch of Atlantis on the STS-125 mission is targeted for Oct. 8. Photo credit: NASA/Kim Shiflett

KSC-08pd2335

NASA Image and Video Library

2008-08-07

CAPE CANAVERAL, Fla. – In the clean room of the Payload Hazardous Processing Facility at NASA's Kennedy Space Center, an overhead crane lowers the Cosmic Origins Spectrograph, or COS, toward a protective enclosure on the Orbital Replacement Unit Carrier, part of the payload for the fifth and final Hubble servicing mission, STS-125. Other payloads include the Flight Support System, the Super Lightweight Interchangeable Carrier and the Multi-Use Lightweight Equipment, or MULE, carrier. COS will be the most sensitive ultraviolet spectrograph ever flown on Hubble and will probe the "cosmic web" - the large-scale structure of the universe whose form is determined by the gravity of dark matter and is traced by galaxies and intergalactic gas. The COS far-ultraviolet channel has a sensitivity 30 times greater than that of previous spectroscopic instruments for the detection of extremely low light levels. Launch of Atlantis on the STS-125 mission is targeted for Oct. 8. Photo credit: NASA/Kim Shiflett

KSC-08pd2338

NASA Image and Video Library

2008-08-07

CAPE CANAVERAL, Fla. – In the clean room of the Payload Hazardous Processing Facility at NASA's Kennedy Space Center, an overhead crane lowers the Cosmic Origins Spectrograph, or COS, into a protective enclosure on the Orbital Replacement Unit Carrier, part of the payload for the fifth and final Hubble servicing mission, STS-125. Other payloads include the Flight Support System, the Super Lightweight Interchangeable Carrier and the Multi-Use Lightweight Equipment, or MULE, carrier. COS will be the most sensitive ultraviolet spectrograph ever flown on Hubble and will probe the "cosmic web" - the large-scale structure of the universe whose form is determined by the gravity of dark matter and is traced by galaxies and intergalactic gas. The COS far-ultraviolet channel has a sensitivity 30 times greater than that of previous spectroscopic instruments for the detection of extremely low light levels. Launch of Atlantis on the STS-125 mission is targeted for Oct. 8. Photo credit: NASA/Kim Shiflett

KSC-08pd2322

NASA Image and Video Library

2008-08-06

CAPE CANAVERAL, Fla. – In the clean room of the Payload Hazardous Processing Facility at NASA's Kennedy Space Center, a worker from NASA's Goddard Space Flight Center uses black light inspection for a thorough cleaning of the Cosmic Origins Spectrograph, or COS. Black light inspection uses UVA fluorescence to detect possible particulate microcontamination, minute cracks or fluid leaks. The COS will be installed on the Hubble Space Telescope on space shuttle Atlantis' STS-125 mission. COS will be the most sensitive ultraviolet spectrograph ever flown on Hubble and will probe the "cosmic web" - the large-scale structure of the universe whose form is determined by the gravity of dark matter and is traced by galaxies and intergalactic gas. The COS far-ultraviolet channel has a sensitivity 30 times greater than that of previous spectroscopic instruments for the detection of extremely low light levels. Launch of Atlantis on the STS-125 mission is targeted for Oct. 8. Photo credit: NASA/Kim Shiflett

KSC-08pd2557

NASA Image and Video Library

2008-09-05

CAPE CANAVERAL, Fla. – In the Payload Hazardous Servicing Facility at NASA’s Kennedy Space Center, crew members with the STS-125 mission get a close look at some of the equipment associated with their mission to service NASA’s Hubble Space Telescope. In the foreground, center, are Mission Specialists Mike Massimino and Michael Good, looking at the box containing the Cosmic Origins Spectrograph, or COS, on the orbital replacement unit carrier. COS will be the most sensitive ultraviolet spectrograph ever flown on Hubble and will probe the "cosmic web" - the large-scale structure of the universe whose form is determined by the gravity of dark matter and is traced by galaxies and intergalactic gas. The STS-125 crew is taking part in a crew equipment interface test, which provides experience handling tools, equipment and hardware they will use on their mission. Space shuttle Atlantis is targeted to launch on the STS-125 mission Oct. 10. Photo credit: NASA/Kim Shiflett

Gravitational redshift of galaxies in clusters as predicted by general relativity.

PubMed

Wojtak, Radosław; Hansen, Steen H; Hjorth, Jens

2011-09-28

The theoretical framework of cosmology is mainly defined by gravity, of which general relativity is the current model. Recent tests of general relativity within the Lambda Cold Dark Matter (ΛCDM) model have found a concordance between predictions and the observations of the growth rate and clustering of the cosmic web. General relativity has not hitherto been tested on cosmological scales independently of the assumptions of the ΛCDM model. Here we report an observation of the gravitational redshift of light coming from galaxies in clusters at the 99 per cent confidence level, based on archival data. Our measurement agrees with the predictions of general relativity and its modification created to explain cosmic acceleration without the need for dark energy (the f(R) theory), but is inconsistent with alternative models designed to avoid the presence of dark matter. © 2011 Macmillan Publishers Limited. All rights reserved

KSC-08pd2337

NASA Image and Video Library

2008-08-07

CAPE CANAVERAL, Fla. – In the clean room of the Payload Hazardous Processing Facility at NASA's Kennedy Space Center, an overhead crane lowers the Cosmic Origins Spectrograph, or COS, into a protective enclosure on the Orbital Replacement Unit Carrier, part of the payload for the fifth and final Hubble servicing mission, STS-125. Other payloads include the Flight Support System, the Super Lightweight Interchangeable Carrier and the Multi-Use Lightweight Equipment, or MULE, carrier. COS will be the most sensitive ultraviolet spectrograph ever flown on Hubble and will probe the "cosmic web" - the large-scale structure of the universe whose form is determined by the gravity of dark matter and is traced by galaxies and intergalactic gas. The COS far-ultraviolet channel has a sensitivity 30 times greater than that of previous spectroscopic instruments for the detection of extremely low light levels. Launch of Atlantis on the STS-125 mission is targeted for Oct. 8. Photo credit: NASA/Kim Shiflett

An intensity map of hydrogen 21-cm emission at redshift z approximately 0.8.

PubMed

Chang, Tzu-Ching; Pen, Ue-Li; Bandura, Kevin; Peterson, Jeffrey B

2010-07-22

Observations of 21-cm radio emission by neutral hydrogen at redshifts z approximately 0.5 to approximately 2.5 are expected to provide a sensitive probe of cosmic dark energy. This is particularly true around the onset of acceleration at z approximately 1, where traditional optical cosmology becomes very difficult because of the infrared opacity of the atmosphere. Hitherto, 21-cm emission has been detected only to z = 0.24. More distant galaxies generally are too faint for individual detections but it is possible to measure the aggregate emission from many unresolved galaxies in the 'cosmic web'. Here we report a three-dimensional 21-cm intensity field at z = 0.53 to 1.12. We then co-add neutral-hydrogen (H i) emission from the volumes surrounding about 10,000 galaxies (from the DEEP2 optical galaxy redshift survey). We detect the aggregate 21-cm glow at a significance of approximately 4sigma.

KSC-08pd2339

NASA Image and Video Library

2008-08-07

CAPE CANAVERAL, Fla. – In the clean room of the Payload Hazardous Processing Facility at NASA's Kennedy Space Center, an overhead crane settles the Cosmic Origins Spectrograph, or COS, in a protective enclosure on the Orbital Replacement Unit Carrier, part of the payload for the fifth and final Hubble servicing mission, STS-125. Other payloads include the Flight Support System, the Super Lightweight Interchangeable Carrier and the Multi-Use Lightweight Equipment, or MULE, carrier. COS will be the most sensitive ultraviolet spectrograph ever flown on Hubble and will probe the "cosmic web" - the large-scale structure of the universe whose form is determined by the gravity of dark matter and is traced by galaxies and intergalactic gas. The COS far-ultraviolet channel has a sensitivity 30 times greater than that of previous spectroscopic instruments for the detection of extremely low light levels. Launch of Atlantis on the STS-125 mission is targeted for Oct. 8. Photo credit: NASA/Kim Shiflett

KSC-08pd2558

NASA Image and Video Library

2008-09-05

CAPE CANAVERAL, Fla. – In the Payload Hazardous Servicing Facility at NASA’s Kennedy Space Center, crew members with the STS-125 mission get a close look at some of the equipment associated with their mission to service NASA’s Hubble Space Telescope. Looking at the box containing the Cosmic Origins Spectrograph, or COS, on the orbital replacement unit carrier are Mission Specialist Michael Good (upper right, on stand) and HST inspectors. COS will be the most sensitive ultraviolet spectrograph ever flown on Hubble and will probe the "cosmic web" - the large-scale structure of the universe whose form is determined by the gravity of dark matter and is traced by galaxies and intergalactic gas. The STS-125 crew is taking part in a crew equipment interface test, which provides experience handling tools, equipment and hardware they will use on their mission. Space shuttle Atlantis is targeted to launch on the STS-125 mission Oct. 10. Photo credit: NASA/Kim Shiflett

KSC-08pd2323

NASA Image and Video Library

2008-08-06

CAPE CANAVERAL, Fla. – In the clean room of the Payload Hazardous Processing Facility at NASA's Kennedy Space Center, a worker from NASA's Goddard Space Flight Center uses black light inspection for a thorough cleaning of the Cosmic Origins Spectrograph, or COS. Black light inspection uses UVA fluorescence to detect possible particulate microcontamination, minute cracks or fluid leaks. The COS will be installed on the Hubble Space Telescope on space shuttle Atlantis' STS-125 mission. COS will be the most sensitive ultraviolet spectrograph ever flown on Hubble and will probe the "cosmic web" - the large-scale structure of the universe whose form is determined by the gravity of dark matter and is traced by galaxies and intergalactic gas. The COS far-ultraviolet channel has a sensitivity 30 times greater than that of previous spectroscopic instruments for the detection of extremely low light levels. Launch of Atlantis on the STS-125 mission is targeted for Oct. 8. Photo credit: NASA/Kim Shiflett

Computer version of astronomical ephemerides.

NASA Astrophysics Data System (ADS)

Choliy, V. Ya.

A computer version of astronomical ephemerides for bodies of the Solar System, stars, and astronomical phenomena was created at the Main Astronomical Observatory of the National Academy of Sciences of Ukraine and the Astronomy and Cosmic Physics Department of the Taras Shevchenko National University. The ephemerides will be distributed via INTERNET or in the file form. This information is accessible via the web servers space.ups.kiev.ua and alfven.ups.kiev.ua or the address choliy@astrophys.ups.kiev.ua.

A giant protogalactic disk linked to the cosmic web

NASA Astrophysics Data System (ADS)

Martin, D. Christopher; Matuszewski, Mateusz; Morrissey, Patrick; Neill, James D.; Moore, Anna; Cantalupo, Sebastiano; Prochaska, J. Xavier; Chang, Daphne

2015-08-01

The specifics of how galaxies form from, and are fuelled by, gas from the intergalactic medium remain uncertain. Hydrodynamic simulations suggest that `cold accretion flows'--relatively cool (temperatures of the order of 104 kelvin), unshocked gas streaming along filaments of the cosmic web into dark-matter halos--are important. These flows are thought to deposit gas and angular momentum into the circumgalactic medium, creating disk- or ring-like structures that eventually coalesce into galaxies that form at filamentary intersections. Recently, a large and luminous filament, consistent with such a cold accretion flow, was discovered near the quasi-stellar object QSO UM287 at redshift 2.279 using narrow-band imaging. Unfortunately, imaging is not sufficient to constrain the physical characteristics of the filament, to determine its kinematics, to explain how it is linked to nearby sources, or to account for its unusual brightness, more than a factor of ten above what is expected for a filament. Here we report a two-dimensional spectroscopic investigation of the emitting structure. We find that the brightest emission region is an extended rotating hydrogen disk with a velocity profile that is characteristic of gas in a dark-matter halo with a mass of 1013 solar masses. This giant protogalactic disk appears to be connected to a quiescent filament that may extend beyond the virial radius of the halo. The geometry is strongly suggestive of a cold accretion flow.

The baryon content of the Cosmic Web

PubMed Central

Eckert, Dominique; Jauzac, Mathilde; Shan, HuanYuan; Kneib, Jean-Paul; Erben, Thomas; Israel, Holger; Jullo, Eric; Klein, Matthias; Massey, Richard; Richard, Johan; Tchernin, Céline

2015-01-01

Big-Bang nucleosynthesis indicates that baryons account for 5% of the Universe’s total energy content[1]. In the local Universe, the census of all observed baryons falls short of this estimate by a factor of two[2,3]. Cosmological simulations indicate that the missing baryons have not yet condensed into virialised halos, but reside throughout the filaments of the cosmic web: a low-density plasma at temperature 105–107 K known as the warm-hot intergalactic medium (WHIM)[3,4,5,6]. There have been previous claims of the detection of warm baryons along the line of sight to distant blazars[7,8,9,10] and hot gas between interacting clusters[11,12,13,14]. These observations were however unable to trace the large-scale filamentary structure, or to estimate the total amount of warm baryons in a representative volume of the Universe. Here we report X-ray observations of filamentary structures of ten-million-degree gas associated with the galaxy cluster Abell 2744. Previous observations of this cluster[15] were unable to resolve and remove coincidental X-ray point sources. After subtracting these, we reveal hot gas structures that are coherent over 8 Mpc scales. The filaments coincide with over-densities of galaxies and dark matter, with 5-10% of their mass in baryonic gas. This gas has been heated up by the cluster's gravitational pull and is now feeding its core. PMID:26632589

A giant protogalactic disk linked to the cosmic web.

PubMed

Martin, D Christopher; Matuszewski, Mateusz; Morrissey, Patrick; Neill, James D; Moore, Anna; Cantalupo, Sebastiano; Prochaska, J Xavier; Chang, Daphne

2015-08-13

The specifics of how galaxies form from, and are fuelled by, gas from the intergalactic medium remain uncertain. Hydrodynamic simulations suggest that 'cold accretion flows'--relatively cool (temperatures of the order of 10(4) kelvin), unshocked gas streaming along filaments of the cosmic web into dark-matter halos--are important. These flows are thought to deposit gas and angular momentum into the circumgalactic medium, creating disk- or ring-like structures that eventually coalesce into galaxies that form at filamentary intersections. Recently, a large and luminous filament, consistent with such a cold accretion flow, was discovered near the quasi-stellar object QSO UM287 at redshift 2.279 using narrow-band imaging. Unfortunately, imaging is not sufficient to constrain the physical characteristics of the filament, to determine its kinematics, to explain how it is linked to nearby sources, or to account for its unusual brightness, more than a factor of ten above what is expected for a filament. Here we report a two-dimensional spectroscopic investigation of the emitting structure. We find that the brightest emission region is an extended rotating hydrogen disk with a velocity profile that is characteristic of gas in a dark-matter halo with a mass of 10(13) solar masses. This giant protogalactic disk appears to be connected to a quiescent filament that may extend beyond the virial radius of the halo. The geometry is strongly suggestive of a cold accretion flow.

Web usage data mining agent

NASA Astrophysics Data System (ADS)

Madiraju, Praveen; Zhang, Yanqing

2002-03-01

When a user logs in to a website, behind the scenes the user leaves his/her impressions, usage patterns and also access patterns in the web servers log file. A web usage mining agent can analyze these web logs to help web developers to improve the organization and presentation of their websites. They can help system administrators in improving the system performance. Web logs provide invaluable help in creating adaptive web sites and also in analyzing the network traffic analysis. This paper presents the design and implementation of a Web usage mining agent for digging in to the web log files.

Fabrication and Test of Large Area Spider-Web Bolometers for CMB Measurements

NASA Astrophysics Data System (ADS)

Biasotti, M.; Ceriale, V.; Corsini, D.; De Gerone, M.; Gatti, F.; Orlando, A.; Pizzigoni, G.

2016-08-01

Detecting the primordial 'B-mode' polarization of the cosmic microwave background is one of the major challenges of modern observational cosmology. Microwave telescopes need sensitive cryogenic bolometers with an overall equivalent noise temperature in the nK range. In this paper, we present the development status of large area (about 1 cm2) spider-web bolometer, which imply additional fabrication challenges. The spider-web is a suspended Si3N4 1 \\upmu m-thick and 8-mm diameter with mesh size of 250 \\upmu m. The thermal sensitive element is a superconducting transition edge sensor (TES) at the center of the bolometer. The first prototype is a Ti-Au TES with transition temperature tuned around 350 mK, new devices will be a Mo-Au bilayer tuned to have a transition temperature of 500 mK. We present the fabrication process with micro-machining techniques from silicon wafer covered with SiO2 - Si3N4 CVD films, 0.3 and 1 \\upmu m- thick, respectively, and preliminary tests.

The energy spectrum of cosmic rays above 1017.2 eV measured by the fluorescence detectors of the Telescope Array experiment in seven years

NASA Astrophysics Data System (ADS)

Abbasi, R. U.; Abe, M.; Abu-Zayyad, T.; Allen, M.; Azuma, R.; Barcikowski, E.; Belz, J. W.; Bergman, D. R.; Blake, S. A.; Cady, R.; Cheon, B. G.; Chiba, J.; Chikawa, M.; Cho, W. R.; Fujii, T.; Fukushima, M.; Goto, T.; Hanlon, W.; Hayashi, Y.; Hayashida, N.; Hibino, K.; Honda, K.; Ikeda, D.; Inoue, N.; Ishii, T.; Ishimori, R.; Ito, H.; Ivanov, D.; Jui, C. C. H.; Kadota, K.; Kakimoto, F.; Kalashev, O.; Kasahara, K.; Kawai, H.; Kawakami, S.; Kawana, S.; Kawata, K.; Kido, E.; Kim, H. B.; Kim, J. H.; Kim, J. H.; Kitamura, S.; Kitamura, Y.; Kuzmin, V.; Kwon, Y. J.; Lan, J.; Lundquist, J. P.; Machida, K.; Martens, K.; Matsuda, T.; Matsuyama, T.; Matthews, J. N.; Minamino, M.; Mukai, Y.; Myers, I.; Nagasawa, K.; Nagataki, S.; Nakamura, T.; Nonaka, T.; Nozato, A.; Ogio, S.; Ogura, J.; Ohnishi, M.; Ohoka, H.; Oki, K.; Okuda, T.; Ono, M.; Oshima, A.; Ozawa, S.; Park, I. H.; Pshirkov, M. S.; Rodriguez, D. C.; Rubtsov, G.; Ryu, D.; Sagawa, H.; Sakurai, N.; Scott, L. M.; Shah, P. D.; Shibata, F.; Shibata, T.; Shimodaira, H.; Shin, B. K.; Shin, H. S.; Smith, J. D.; Sokolsky, P.; Springer, R. W.; Stokes, B. T.; Stratton, S. R.; Stroman, T. A.; Suzawa, T.; Takamura, M.; Takeda, M.; Takeishi, R.; Taketa, A.; Takita, M.; Tameda, Y.; Tanaka, H.; Tanaka, K.; Tanaka, M.; Thomas, S. B.; Thomson, G. B.; Tinyakov, P.; Tkachev, I.; Tokuno, H.; Tomida, T.; Troitsky, S.; Tsunesada, Y.; Tsutsumi, K.; Uchihori, Y.; Udo, S.; Urban, F.; Vasiloff, G.; Wong, T.; Yamane, R.; Yamaoka, H.; Yamazaki, K.; Yang, J.; Yashiro, K.; Yoneda, Y.; Yoshida, S.; Yoshii, H.; Zollinger, R.; Zundel, Z.

2016-07-01

The Telescope Array (TA) experiment is the largest detector to observe ultra-high-energy cosmic rays in the northern hemisphere. The fluorescence detectors at two stations of TA are newly constructed and have now completed seven years of steady operation. One advantage of monocular analysis of the fluorescence detectors is a lower energy threshold for cosmic rays than that of other techniques like stereoscopic observations or coincidences with the surface detector array, allowing the measurement of an energy spectrum covering three orders of magnitude in energy. Analyzing data collected during those seven years, we report the energy spectrum of cosmic rays covering a broad range of energies above 1017.2eV measured by the fluorescence detectors and a comparison with previously published results.

Deriving the solar activity cycle modulation on cosmic ray intensity observed by Nagoya muon detector from October 1970 until December 2012

NASA Astrophysics Data System (ADS)

de Mendonça, Rafael R. S.; Braga, Carlos. R.; Echer, Ezequiel; Dal Lago, Alisson; Rockenbach, Marlos; Schuch, Nelson J.; Munakata, Kazuoki

2017-10-01

It is well known that the cosmic ray intensity observed at the Earth's surface presents an 11 and 22-yr variations associated with the solar activity cycle. However, the observation and analysis of this modulation through ground muon detectors datahave been difficult due to the temperature effect. Furthermore, instrumental changes or temporary problems may difficult the analysis of these variations. In this work, we analyze the cosmic ray intensity observed since October 1970 until December 2012 by the Nagoya muon detector. We show the results obtained after analyzing all discontinuities and gaps present in this data and removing changes not related to natural phenomena. We also show the results found using the mass weighted method for eliminate the influence of atmospheric temperature changes on muon intensity observed at ground. As a preliminary result of our analyses, we show the solar cycle modulation in the muon intensity observed for more than 40 years.

Light ion components of the galactic cosmic rays: Nuclear interactions and transport theory

NASA Technical Reports Server (NTRS)

Cucinotta, F. A.; Townsend, L. W.; Wilson, J. W.; Shinn, J. L.; Badhwar, G. D.; Dubey, R. R.

1996-01-01

Light nuclei are present in the primary galactic cosmic rays (GCR) and are produced in thick targets due to projectile or target fragmentation from both nucleon and heavy induced reactions. In the primary GCR, He-4 is the most abundant nucleus after H-1. However, there are also a substantial fluxes of H-2 and He-3. In this paper we describe theoretical models based on quantum multiple scattering theory for the description of light ion nuclear interactions. The energy dependence of the light ion fragmentation cross section is considered with comparisons of inclusive yields and secondary momentum distributions to experiments described. We also analyze the importance of a fast component of lights ions from proton and neutron induced target fragementation. These theoretical models have been incorporated into the cosmic ray transport code HZETRN and will be used to analyze the role of shielding materials in modulating the production and the energy spectrum of light ions.

Planetary exploration with nanosatellites: a space campus for future technology development

NASA Astrophysics Data System (ADS)

Drossart, P.; Mosser, B.; Segret, B.

2017-09-01

Planetary exploration is at the eve of a revolution through nanosatellites accompanying larger missions, or freely cruising in the solar system, providing a man-made cosmic web for in situ or remote sensing exploration of the Solar System. A first step is to build a specific place dedicated to nanosatellite development. The context of the CCERES PSL space campus presents an environment for nanosatellite testing and integration, a concurrent engineering facility room for project analysis and science environment dedicated to this task.

Origin and transport of high energy particles in the galaxy

NASA Technical Reports Server (NTRS)

Wefel, John P.

1987-01-01

The origin, confinement, and transport of cosmic ray nuclei in the galaxy was studied. The work involves interpretations of the existing cosmic ray physics database derived from both balloon and satellite measurements, combined with an effort directed towards defining the next generation of instruments for the study of cosmic radiation. The shape and the energy dependence of the cosmic ray pathlength distribution in the galaxy was studied, demonstrating that the leaky box model is not a good representation of the detailed particle transport over the energy range covered by the database. Alternative confinement methods were investigated, analyzing the confinement lifetime in these models based upon the available data for radioactive secondary isotopes. The source abundances of several isotopes were studied using compiled nuclear physics data and the detailed transport calculations. The effects of distributed particle acceleration on the secondary to primary ratios were investigated.

Zenith angle distribution of cosmic ray showers measured with the Yakutsk array and its application to the analysis of arrival directions in equatorial coordinates

NASA Astrophysics Data System (ADS)

Ivanov, A. A.

2018-04-01

The Yakutsk array data set in the energy interval (1017,1019) eV is revisited in order to interpret the zenith angle distribution of an extensive air shower event rate of ultra-high-energy cosmic rays. The close relation of the distribution to the attenuation of the main measurable parameter of showers, ρ600, is examined. Measured and expected distributions are used to analyze the arrival directions of cosmic rays on an equatorial map including the energy range below 1018 eV , which was previously avoided due to the reduced trigger efficiency of the array in the range. While the null hypothesis cannot be rejected with data from the Yakutsk array, an upper limit on the fraction of cosmic rays from a separable source in the uniform background is derived as a function of declination and energy.

Is cosmic acceleration slowing down?

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

Shafieloo, Arman; Sahni, Varun; Starobinsky, Alexei A.

2009-11-15

We investigate the course of cosmic expansion in its recent past using the Constitution SN Ia sample, along with baryon acoustic oscillations (BAO) and cosmic microwave background (CMB) data. Allowing the equation of state of dark energy (DE) to vary, we find that a coasting model of the universe (q{sub 0}=0) fits the data about as well as Lambda cold dark matter. This effect, which is most clearly seen using the recently introduced Om diagnostic, corresponds to an increase of Om and q at redshifts z < or approx. 0.3. This suggests that cosmic acceleration may have already peaked andmore » that we are currently witnessing its slowing down. The case for evolving DE strengthens if a subsample of the Constitution set consisting of SNLS+ESSENCE+CfA SN Ia data is analyzed in combination with BAO+CMB data. The effect we observe could correspond to DE decaying into dark matter (or something else)« less

Search for microquasar features in cosmic ray spectra with AMS-01

NASA Astrophysics Data System (ADS)

Monreal, Benjamin

2004-12-01

Accreting x-ray binaries are sometimes observed to emit compact, relativistic jets of cool plasma; these objects are called "microquasars". It is possible that these jets are responsible for a large flux of galactic cosmic ray protons and nuclei. The energy spectrum from these sources will be very different from the featureless power-law expected from ordinary cosmic-ray acceleration in supernova shocks. The AMS-01 instrument measured cosmic ray protons and helium during 10 days on the Space Shuttle Discovery in 1998; we analyze this data searching for spectral distortions due to nearby microquasar activity. We show that the microquasar contribution to the CR proton flux can be no more than ~2% in the range 2-50 GeV. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617-253-5668; Fax 617-253-1690.)

Observation of cosmic-ray anisotropy in the decade below 1 PeV with a pentagon array

NASA Astrophysics Data System (ADS)

Moghaddam, S. Mortazavi; Bahmanabadi, M.

2018-03-01

The study of the anisotropy of the arrival directions is an essential tool to investigate the origin and propagation of cosmic rays primaries. A pentagon array has been designed to collect data around the knee region of cosmic ray spectrum. The experimental results of this array obtained from October 2016 to October 2017. During this period, more than 5.3 ×105 extensive air shower events at energies in the decade below 1 PeV has been accumulated by this array at Sharif University of Technology in Tehran (3 5 ° 4 3'N , 5 1 ° 2 0'E , 1200m a .s .l =890 g cm-2 ). In analyzing the data set, we have used appropriate techniques of analysis and considered environmental effects. We report the analysis of the sidereal anisotropy of Galactic cosmic rays (GCRs). In this analysis, in addition to the Compton- Getting effect due to the motion of the earth in the Galaxy, an anisotropy has been observed which is due to a unidirectional anisotropy of cosmic ray flow along the Galactic arms.

High resolution X- and gamma-ray spectroscopy of cosmic X-ray sources

NASA Technical Reports Server (NTRS)

Lin, R. P.

1983-01-01

A high resolution X-ray spectrometer and large area phoswich detector were designed and co-aligned in a common elevation mounting in order to measure solar and cosmic X-ray and gamma ray emission in the 13 to 600 KeV energy range from a balloon. The instrument is described and results obtained for the Crab Nebula, the supernova remnant Cas A, and the Sun are discussed and analyzed.

Extracting knowledge from the World Wide Web

PubMed Central

Henzinger, Monika; Lawrence, Steve

2004-01-01

The World Wide Web provides a unprecedented opportunity to automatically analyze a large sample of interests and activity in the world. We discuss methods for extracting knowledge from the web by randomly sampling and analyzing hosts and pages, and by analyzing the link structure of the web and how links accumulate over time. A variety of interesting and valuable information can be extracted, such as the distribution of web pages over domains, the distribution of interest in different areas, communities related to different topics, the nature of competition in different categories of sites, and the degree of communication between different communities or countries. PMID:14745041

Could multiple voids explain the cosmic microwave background Cold Spot anomaly?

DOE PAGES

Naidoo, Krishna; Benoit-Levy, Aurelien; Lahav, Ofer

2016-03-20

Understanding the observed Cold Spot (CS) (temperature of ~ -150 mu K at its centre) on the Cosmic Microwave Background (CMB) is an outstanding problem. Explanations vary from assuming it is just a ≳ 3σ primordial Gaussian fluctuation to the imprint of a supervoid via the Integrated Sachs-Wolfe and Rees-Sciama (ISW+RS) effects. Since single spherical supervoids cannot account for the full profile, the ISW+RS of multiple line-of-sight voids is studied here to mimic the structure of the cosmic web. Two structure configurations are considered. The first, through simulations of 20 voids, produces a central mean temperature of ~-50 mu K.more » In this model the central CS temperature lies at ~ 2σ but fails to explain the CS hot ring. An alternative multi-void model (using more pronounced compensated voids) produces much smaller temperature profiles, but contains a prominent hot ring. Arrangements containing closely placed voids at low redshift are found to be particularly well suited to produce CS-like profiles. We then measure the significance of the CS if CS-like profiles (which are fitted to the ISW+RS of multi-void scenarios) are removed. Furthermore, the CS tension with the LCDM model can be reduced dramatically for an array of temperature profiles smaller than the CS itself.« less

Simulations of extragalactic magnetic fields and of their observables

NASA Astrophysics Data System (ADS)

Vazza, F.; Brüggen, M.; Gheller, C.; Hackstein, S.; Wittor, D.; Hinz, P. M.

2017-12-01

The origin of extragalactic magnetic fields is still poorly understood. Based on a dedicated suite of cosmological magneto-hydrodynamical simulations with the ENZO code we have performed a survey of different models that may have caused present-day magnetic fields in galaxies and galaxy clusters. The outcomes of these models differ in cluster outskirts, filaments, sheets and voids and we use these simulations to find observational signatures of magnetogenesis. With these simulations, we predict the signal of extragalactic magnetic fields in radio observations of synchrotron emission from the cosmic web, in Faraday rotation, in the propagation of ultra high energy cosmic rays, in the polarized signal from fast radio bursts at cosmological distance and in spectra of distant blazars. In general, primordial scenarios in which present-day magnetic fields originate from the amplification of weak (⩽nG ) uniform seed fields result in more homogeneous and relatively easier to observe magnetic fields than astrophysical scenarios, in which present-day fields are the product of feedback processes triggered by stars and active galaxies. In the near future the best evidence for the origin of cosmic magnetic fields will most likely come from a combination of synchrotron emission and Faraday rotation observed at the periphery of large-scale structures.

Recent Progress in Laboratory Astrophysics and Astrochemistry Achieved with the COSmIC Facility

NASA Technical Reports Server (NTRS)

Salama, Farid; Sciamma-O'Brien, Ella; Bejaoui, Salma

2017-01-01

We describe the characteristics and the capabilities of the laboratory facility, COSmIC, that was developed at NASA Ames to generate, process and analyze interstellar, circumstellar and planetary analogs in the laboratory. COSmIC stands for "Cosmic Simulation Chamber" and is dedicated to the study of neutral and ionized molecules and nanoparticles under the low temperature and high vacuum conditions that are required to simulate various space environments such as diffuse interstellar clouds, circumstellar outflows and planetary atmospheres. COSmIC integrates a variety of state-of-the-art instruments that allow recreating simulated space conditions to generate, process and monitor cosmic analogs in the laboratory. The COSmIC experimental setup is composed of a Pulsed Discharge Nozzle (PDN) expansion, that generates a plasma in the stream of a free supersonic jet expansion, coupled to high-sensitivity, complementary in situ diagnostics: cavity ring down spectroscopy (CRDS) and laser induced fluorescence (LIF) systems for photonic detection, and Reflectron Time-Of-Flight Mass Spectrometer (ReTOF-MS) for mass detection. Recent results obtained using COSmIC will be highlighted. In particular, the progress that has been achieved in the domain of the diffuse interstellar bands (DIBs) and in monitoring, in the laboratory, the formation of circumstellar dust grains and planetary atmosphere aerosols from their gas-phase molecular precursors. Plans for future laboratory experiments on interstellar and planetary molecules and grains will also be addressed, as well as the implications of the studies underway for astronomical observations and past and future space mission data analysis.

Estimates of galactic cosmic ray shielding requirements during solar minimum

NASA Technical Reports Server (NTRS)

Townsend, Lawrence W.; Nealy, John E.; Wilson, John W.; Simonsen, Lisa C.

1990-01-01

Estimates of radiation risk from galactic cosmic rays are presented for manned interplanetary missions. The calculations use the Naval Research Laboratory cosmic ray spectrum model as input into the Langley Research Center galactic cosmic ray transport code. This transport code, which transports both heavy ions and nucleons, can be used with any number of layers of target material, consisting of up to five different arbitrary constituents per layer. Calculated galactic cosmic ray fluxes, dose and dose equivalents behind various thicknesses of aluminum, water and liquid hydrogen shielding are presented for the solar minimum period. Estimates of risk to the skin and the blood-forming organs (BFO) are made using 0-cm and 5-cm depth dose/dose equivalent values, respectively, for water. These results indicate that at least 3.5 g/sq cm (3.5 cm) of water, or 6.5 g/sq cm (2.4 cm) of aluminum, or 1.0 g/sq cm (14 cm) of liquid hydrogen shielding is required to reduce the annual exposure below the currently recommended BFO limit of 0.5 Sv. Because of large uncertainties in fragmentation parameters and the input cosmic ray spectrum, these exposure estimates may be uncertain by as much as a factor of 2 or more. The effects of these potential exposure uncertainties or shield thickness requirements are analyzed.

VORTICAL MOTIONS OF BARYONIC GAS IN THE COSMIC WEB: GROWTH HISTORY AND SCALING RELATION

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

Zhu, Weishan; Feng, Long-long

The vortical motions of the baryonic gas residing in large-scale structures are investigated by cosmological hydrodynamic simulations. Proceeding in the formation of the cosmic web, the vortical motions of baryonic matter are pumped up by baroclinity in two stages, i.e., the formation of sheets and filaments. The mean curl velocities are about <1, 1–10, 10–150, and 5–50 km s{sup −1} in voids, sheets, filaments, and knots at z = 0, respectively. The scaling of the vortical velocity of gas can be well described by the She–Leveque hierarchical turbulence model in the range of l < 0.65(1.50) h{sup −1} Mpc inmore » a simulation with a box of size 25(100) h{sup −1} Mpc. The fractal Hausdorff dimension of vortical motions, d, revealed by velocity structure functions, is ∼2.1–2.3(∼1.8–2.1). It is slightly larger than the fractal dimension of mass distribution in filaments, D{sup f} ∼ 1.9–2.2, and smaller than the fractal dimension of sheets, D{sup s} ∼ 2.4–2.7. The vortical kinetic energy of baryonic gas is mainly transported by filaments. Both scalings of mass distribution and vortical velocity increments show distinctive transitions at the turning scale of ∼0.65(1.50) h{sup −1} Mpc, which may be closely related to the characteristic radius of density filaments.« less

Pre-inflation from the multiverse: can it solve the quadrupole problem in the cosmic microwave background?

NASA Astrophysics Data System (ADS)

Morais, João; Bouhmadi-López, Mariam; Krämer, Manuel; Robles-Pérez, Salvador

2018-03-01

We analyze a quantized toy model of a universe undergoing eternal inflation using a quantum-field-theoretical formulation of the Wheeler-DeWitt equation. This so-called third quantization method leads to the picture that the eternally inflating universe is converted to a multiverse in which sub-universes are created and exhibit a distinctive phase in their evolution before reaching an asymptotic de Sitter phase. From the perspective of one of these sub-universes, we can thus analyze the pre-inflationary phase that arises naturally. Assuming that our observable universe is represented by one of those sub-universes, we calculate how this pre-inflationary phase influences the power spectrum of the cosmic microwave background (CMB) anisotropies and analyze whether it can explain the observed discrepancy of the power spectrum on large scales, i.e. the quadrupole issue in the CMB. While the answer to this question is negative in the specific model analyzed here, we point out a possible resolution of this issue.

Pre-inflation from the multiverse: can it solve the quadrupole problem in the cosmic microwave background?

PubMed

Morais, João; Bouhmadi-López, Mariam; Krämer, Manuel; Robles-Pérez, Salvador

2018-01-01

We analyze a quantized toy model of a universe undergoing eternal inflation using a quantum-field-theoretical formulation of the Wheeler-DeWitt equation. This so-called third quantization method leads to the picture that the eternally inflating universe is converted to a multiverse in which sub-universes are created and exhibit a distinctive phase in their evolution before reaching an asymptotic de Sitter phase. From the perspective of one of these sub-universes, we can thus analyze the pre-inflationary phase that arises naturally. Assuming that our observable universe is represented by one of those sub-universes, we calculate how this pre-inflationary phase influences the power spectrum of the cosmic microwave background (CMB) anisotropies and analyze whether it can explain the observed discrepancy of the power spectrum on large scales, i.e. the quadrupole issue in the CMB. While the answer to this question is negative in the specific model analyzed here, we point out a possible resolution of this issue.

A SPDS Node to Support the Systematic Interpretation of Cosmic Ray Data

NASA Technical Reports Server (NTRS)

1997-01-01

The purpose of this project was to establish and maintain a Space Physics Data System (SPDS) node that supports the analysis and interpretation of current and future galactic cosmic ray (GCR) measurements by (1) providing on-line databases relevant to GCR propagation studies; (2) providing other on-line services, such as anonymous FTP access, mail list service and pointers to e-mail address books, to support the cosmic ray community; (3) providing a mechanism for those in the community who might wish to submit similar contributions for public access; (4) maintaining the node to assure that the databases remain current; and (5) investigating other possibilities, such as CD-ROM, for public dissemination of the data products. Shortly after the original grant to support these activities was established at Louisiana State University a detailed study of alternate choices for the node hardware was initiated. The chosen hardware was an Apple Workgroup Server 9150/120 consisting of a 120 MHz PowerPC 601 processor, 32 MB of memory, two I GB disks and one 2 GB disk. This hardware was ordered and installed and has been operating reliably ever since. A preliminary version of the database server was available during the first year effort and was used as part of the very successful SPDS demonstration during the Rome, Italy International Cosmic Ray Conference. For this server version we were able to establish the html and anonymous FTP server software, develop a Web page structure which can be easily modified to include new items, provide an on-line database of charge changing total cross sections, include the cross section prediction software of Silberberg & Tsao as well as Webber, Kish and Schrier for download access, and provide an on-line bibliography of the cross section measurement references by the Transport Collaboration. The preliminary version of this SPDS Cosmic Ray node was examined by members of the C&H SPDS committee and returned comments were used to refine the implementation.

Filaments from the galaxy distribution and from the velocity field in the local universe

NASA Astrophysics Data System (ADS)

Libeskind, Noam I.; Tempel, Elmo; Hoffman, Yehuda; Tully, R. Brent; Courtois, Hélène

2015-10-01

The cosmic web that characterizes the large-scale structure of the Universe can be quantified by a variety of methods. For example, large redshift surveys can be used in combination with point process algorithms to extract long curvilinear filaments in the galaxy distribution. Alternatively, given a full 3D reconstruction of the velocity field, kinematic techniques can be used to decompose the web into voids, sheets, filaments and knots. In this Letter, we look at how two such algorithms - the Bisous model and the velocity shear web - compare with each other in the local Universe (within 100 Mpc), finding good agreement. This is both remarkable and comforting, given that the two methods are radically different in ideology and applied to completely independent and different data sets. Unsurprisingly, the methods are in better agreement when applied to unbiased and complete data sets, like cosmological simulations, than when applied to observational samples. We conclude that more observational data is needed to improve on these methods, but that both methods are most likely properly tracing the underlying distribution of matter in the Universe.

KSC-08pd2326

NASA Image and Video Library

2008-08-07

CAPE CANAVERAL, Fla. – In the clean room of the Payload Hazardous Processing Facility at NASA's Kennedy Space Center, workers prepare to attach an overhead crane to the Cosmic Origins Spectrograph, or COS. The COS will be lifted and moved to a protective enclosure on the Orbital Replacement Unit Carrier, part of the payload for the fifth and final Hubble servicing mission, STS-125. Other payloads include the Flight Support System, the Super Lightweight Interchangeable Carrier and the Multi-Use Lightweight Equipment, or MULE, carrier. COS will be the most sensitive ultraviolet spectrograph ever flown on Hubble and will probe the "cosmic web" - the large-scale structure of the universe whose form is determined by the gravity of dark matter and is traced by galaxies and intergalactic gas. The COS far-ultraviolet channel has a sensitivity 30 times greater than that of previous spectroscopic instruments for the detection of extremely low light levels. Launch of Atlantis on the STS-125 mission is targeted for Oct. 8. Photo credit: NASA/Kim Shiflett

KSC-08pd2327

NASA Image and Video Library

2008-08-07

CAPE CANAVERAL, Fla. – In the clean room of the Payload Hazardous Processing Facility at NASA's Kennedy Space Center, workers attach an overhead crane to the Cosmic Origins Spectrograph, or COS. The COS is being lifted and moved to a protective enclosure on the Orbital Replacement Unit Carrier, part of the payload for the fifth and final Hubble servicing mission, STS-125. Other payloads include the Flight Support System, the Super Lightweight Interchangeable Carrier and the Multi-Use Lightweight Equipment, or MULE, carrier. COS will be the most sensitive ultraviolet spectrograph ever flown on Hubble and will probe the "cosmic web" - the large-scale structure of the universe whose form is determined by the gravity of dark matter and is traced by galaxies and intergalactic gas. The COS far-ultraviolet channel has a sensitivity 30 times greater than that of previous spectroscopic instruments for the detection of extremely low light levels. Launch of Atlantis on the STS-125 mission is targeted for Oct. 8. Photo credit: NASA/Kim Shiflett

KSC-08pd2330

NASA Image and Video Library

2008-08-07

CAPE CANAVERAL, Fla. – In the clean room of the Payload Hazardous Processing Facility at NASA's Kennedy Space Center, an overhead crane lifts the Cosmic Origins Spectrograph, or COS. The COS is being lifted and moved to a protective enclosure on the Orbital Replacement Unit Carrier, part of the payload for the fifth and final Hubble servicing mission, STS-125. Other payloads include the Flight Support System, the Super Lightweight Interchangeable Carrier and the Multi-Use Lightweight Equipment, or MULE, carrier. COS will be the most sensitive ultraviolet spectrograph ever flown on Hubble and will probe the "cosmic web" - the large-scale structure of the universe whose form is determined by the gravity of dark matter and is traced by galaxies and intergalactic gas. The COS far-ultraviolet channel has a sensitivity 30 times greater than that of previous spectroscopic instruments for the detection of extremely low light levels. Launch of Atlantis on the STS-125 mission is targeted for Oct. 8. Photo credit: NASA/Kim Shiflett

KSC-08pd2331

NASA Image and Video Library

2008-08-07

CAPE CANAVERAL, Fla. – In the clean room of the Payload Hazardous Processing Facility at NASA's Kennedy Space Center, an overhead crane lifts the Cosmic Origins Spectrograph, or COS. The COS is being lifted and moved to a protective enclosure on the Orbital Replacement Unit Carrier, part of the payload for the fifth and final Hubble servicing mission, STS-125. Other payloads include the Flight Support System, the Super Lightweight Interchangeable Carrier and the Multi-Use Lightweight Equipment, or MULE, carrier. COS will be the most sensitive ultraviolet spectrograph ever flown on Hubble and will probe the "cosmic web" - the large-scale structure of the universe whose form is determined by the gravity of dark matter and is traced by galaxies and intergalactic gas. The COS far-ultraviolet channel has a sensitivity 30 times greater than that of previous spectroscopic instruments for the detection of extremely low light levels. Launch of Atlantis on the STS-125 mission is targeted for Oct. 8. Photo credit: NASA/Kim Shiflett

KSC-08pd2328

NASA Image and Video Library

2008-08-07

CAPE CANAVERAL, Fla. – In the clean room of the Payload Hazardous Processing Facility at NASA's Kennedy Space Center, an overhead crane lifts the Cosmic Origins Spectrograph, or COS. The COS is being lifted and moved to a protective enclosure on the Orbital Replacement Unit Carrier, part of the payload for the fifth and final Hubble servicing mission, STS-125. Other payloads include the Flight Support System, the Super Lightweight Interchangeable Carrier and the Multi-Use Lightweight Equipment, or MULE, carrier. COS will be the most sensitive ultraviolet spectrograph ever flown on Hubble and will probe the "cosmic web" - the large-scale structure of the universe whose form is determined by the gravity of dark matter and is traced by galaxies and intergalactic gas. The COS far-ultraviolet channel has a sensitivity 30 times greater than that of previous spectroscopic instruments for the detection of extremely low light levels. Launch of Atlantis on the STS-125 mission is targeted for Oct. 8. Photo credit: NASA/Kim Shiflett

KSC-08pd2318

NASA Image and Video Library

2008-08-06

CAPE CANAVERAL, Fla. – In the clean room of the Payload Hazardous Processing Facility at NASA's Kennedy Space Center, workers from NASA's Goddard Space Flight Center use black light inspection for a thorough cleaning of the protective carrier for the Cosmic Origins Spectrograph, or COS. Black light inspection uses UVA fluorescence to detect possible particulate microcontamination, minute cracks or fluid leaks. The COS will be installed on the Hubble Space Telescope on space shuttle Atlantis' STS-125 mission. COS will be the most sensitive ultraviolet spectrograph ever flown on Hubble and will probe the "cosmic web" - the large-scale structure of the universe whose form is determined by the gravity of dark matter and is traced by galaxies and intergalactic gas. The COS far-ultraviolet channel has a sensitivity 30 times greater than that of previous spectroscopic instruments for the detection of extremely low light levels. Launch of Atlantis on the STS-125 mission is targeted for Oct. 8. Photo credit: NASA/Kim Shiflett

KSC-08pd2319

NASA Image and Video Library

2008-08-06

CAPE CANAVERAL, Fla. – In the clean room of the Payload Hazardous Processing Facility at NASA's Kennedy Space Center, workers from NASA's Goddard Space Flight Center use black light inspection for a thorough cleaning of the protective carrier for the Cosmic Origins Spectrograph, or COS. Black light inspection uses UVA fluorescence to detect possible particulate microcontamination, minute cracks or fluid leaks. The COS will be installed on the Hubble Space Telescope on space shuttle Atlantis' STS-125 mission. COS will be the most sensitive ultraviolet spectrograph ever flown on Hubble and will probe the "cosmic web" - the large-scale structure of the universe whose form is determined by the gravity of dark matter and is traced by galaxies and intergalactic gas. The COS far-ultraviolet channel has a sensitivity 30 times greater than that of previous spectroscopic instruments for the detection of extremely low light levels. Launch of Atlantis on the STS-125 mission is targeted for Oct. 8. Photo credit: NASA/Kim Shiflett

KSC-08pd2329

NASA Image and Video Library

2008-08-07

CAPE CANAVERAL, Fla. – In the clean room of the Payload Hazardous Processing Facility at NASA's Kennedy Space Center, an overhead crane lifts the Cosmic Origins Spectrograph, or COS. The COS is being lifted and moved to a protective enclosure on the Orbital Replacement Unit Carrier, part of the payload for the fifth and final Hubble servicing mission, STS-125. Other payloads include the Flight Support System, the Super Lightweight Interchangeable Carrier and the Multi-Use Lightweight Equipment, or MULE, carrier. COS will be the most sensitive ultraviolet spectrograph ever flown on Hubble and will probe the "cosmic web" - the large-scale structure of the universe whose form is determined by the gravity of dark matter and is traced by galaxies and intergalactic gas. The COS far-ultraviolet channel has a sensitivity 30 times greater than that of previous spectroscopic instruments for the detection of extremely low light levels. Launch of Atlantis on the STS-125 mission is targeted for Oct. 8. Photo credit: NASA/Kim Shiflett

Analysis of pathology department Web sites and practical recommendations.

PubMed

Nero, Christopher; Dighe, Anand S

2008-09-01

There are numerous customers for pathology departmental Web sites, including pathology department staff, clinical staff, residency applicants, job seekers, and other individuals outside the department seeking department information. Despite the increasing importance of departmental Web sites as a means of distributing information, no analysis has been done to date of the content and usage of pathology department Web sites. In this study, we analyzed pathology department Web sites to examine the elements present on each site and to evaluate the use of search technology on these sites. Further, we examined the usage patterns of our own departmental Internet and internet Web sites to better understand the users of pathology Web sites. We reviewed selected departmental pathology Web sites and analyzed their content and functionality. Our institution's departmental pathology Web sites were modified to enable detailed information to be stored regarding users and usage patterns, and that information was analyzed. We demonstrate considerable heterogeneity in departmental Web sites with many sites lacking basic content and search features. In addition, we demonstrate that increasing the traffic of a department's informational Web sites may result in reduced phone inquiries to the laboratory. We propose recommendations for pathology department Web sites to maximize promotion of a department's mission. A departmental pathology Web site is an essential communication tool for all pathology departments, and attention to the users and content of the site can have operational impact.

Analyzing Web Server Logs to Improve a Site's Usage. The Systems Librarian

ERIC Educational Resources Information Center

Breeding, Marshall

2005-01-01

This column describes ways to streamline and optimize how a Web site works in order to improve both its usability and its visibility. The author explains how to analyze logs and other system data to measure the effectiveness of the Web site design and search engine.

Predicting space climate change

NASA Astrophysics Data System (ADS)

Balcerak, Ernie

2011-10-01

Galactic cosmic rays and solar energetic particles can be hazardous to humans in space, damage spacecraft and satellites, pose threats to aircraft electronics, and expose aircrew and passengers to radiation. A new study shows that these threats are likely to increase in coming years as the Sun approaches the end of the period of high solar activity known as “grand solar maximum,” which has persisted through the past several decades. High solar activity can help protect the Earth by repelling incoming galactic cosmic rays. Understanding the past record can help scientists predict future conditions. Barnard et al. analyzed a 9300-year record of galactic cosmic ray and solar activity based on cosmogenic isotopes in ice cores as well as on neutron monitor data. They used this to predict future variations in galactic cosmic ray flux, near-Earth interplanetary magnetic field, sunspot number, and probability of large solar energetic particle events. The researchers found that the risk of space weather radiation events will likely increase noticeably over the next century compared with recent decades and that lower solar activity will lead to increased galactic cosmic ray levels. (Geophysical Research Letters, doi:10.1029/2011GL048489, 2011)

Analysis of Geomagnetic Disturbances and Cosmic Ray Intensity Variations in Relation to Medical Data from Rome

NASA Astrophysics Data System (ADS)

Giannaropoulou, E.; Papailiou, M.; Mavromichalaki, H.; Tsipis, A.

2010-07-01

Over the last few years many studies have been conducted concerning the possible influence of geomagnetic and solar activity and cosmic ray activity on human physiological state and in particular on human cardio - health state. As it is shown the human organism is sensitive to environmental changes and reacts to them through a series of variations of its physiological parameters such as heart rate, arterial systolic and diastolic blood pressure, etc. In this paper daily mean values of heart rate, as they were registered for a group of 2.028 volunteers during medical examinations in the Polyclinico Tor Vergata, Rome, Italy are analyzed in relation to daily cosmic ray intensity variations, as measured by the Neutron Monitor of the University of Athens and daily variations of the geomagnetic indices Dst, Ap and Kp. The results from this study show that geomagnetic activity changes and cosmic rays intensity variations may regulate the human homeostasis.

Computing the universe: how large-scale simulations illuminate galaxies and dark energy

NASA Astrophysics Data System (ADS)

O'Shea, Brian

2015-04-01

High-performance and large-scale computing is absolutely to understanding astronomical objects such as stars, galaxies, and the cosmic web. This is because these are structures that operate on physical, temporal, and energy scales that cannot be reasonably approximated in the laboratory, and whose complexity and nonlinearity often defies analytic modeling. In this talk, I show how the growth of computing platforms over time has facilitated our understanding of astrophysical and cosmological phenomena, focusing primarily on galaxies and large-scale structure in the Universe.

SEEDisCs: How Clusters Form and Galaxies Transform in the Cosmic Web

NASA Astrophysics Data System (ADS)

Jablonka, P.

2017-08-01

This presentation introduces a new survey, the Spatial Extended EDisCS Survey (SEEDisCS), which aims at understanding how clusters assemble and the level at which galaxies are preprocessed before falling on the cluster cores. I focus on the changes in galaxy properties in the cluster large scale environments, and how we can get constraints on the timescale of star formation quenching. I also discuss new ALMA CO observations, which trace the fate of the galaxy cold gas content along the infalling paths towards the cluster cores.

Analyzing the cosmic variance limit of remote dipole measurements of the cosmic microwave background using the large-scale kinetic Sunyaev Zel'dovich effect

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

Terrana, Alexandra; Johnson, Matthew C.; Harris, Mary-Jean, E-mail: aterrana@perimeterinstitute.ca, E-mail: mharris8@perimeterinstitute.ca, E-mail: mjohnson@perimeterinstitute.ca

Due to cosmic variance we cannot learn any more about large-scale inhomogeneities from the primary cosmic microwave background (CMB) alone. More information on large scales is essential for resolving large angular scale anomalies in the CMB. Here we consider cross correlating the large-scale kinetic Sunyaev Zel'dovich (kSZ) effect and probes of large-scale structure, a technique known as kSZ tomography. The statistically anisotropic component of the cross correlation encodes the CMB dipole as seen by free electrons throughout the observable Universe, providing information about long wavelength inhomogeneities. We compute the large angular scale power asymmetry, constructing the appropriate transfer functions, andmore » estimate the cosmic variance limited signal to noise for a variety of redshift bin configurations. The signal to noise is significant over a large range of power multipoles and numbers of bins. We present a simple mode counting argument indicating that kSZ tomography can be used to estimate more modes than the primary CMB on comparable scales. A basic forecast indicates that a first detection could be made with next-generation CMB experiments and galaxy surveys. This paper motivates a more systematic investigation of how close to the cosmic variance limit it will be possible to get with future observations.« less

Cosmic Rays and Clouds, 1. Formation of Lead Mesoatoms In Neutron Monitor By Soft Negative Muons and Expected Atmospheric Electric Field Effect In The Cosmic Ray Neutron Component

NASA Astrophysics Data System (ADS)

Dorman, L. I.; Dorman, I. V.

We extend our model (Dorman and Dorman, 1995) of cosmic ray atmospheric electric field effect on the case of neutron monitor. We take into account that about 0.07 of neu- tron monitor counting rate caused by negative soft muons captured by lead nucleons and formed mesoatoms with generation of several MeV energy neutrons from lead. In this case the neutron monitor or neutron supermonitor works as analyzer which de- tects muons of only one, negative sign. It is very important because the atmospheric electric field effect have opposite signs for positive and negative muons that main part of this effect in the muon telescope or in ionization chamber is compensated and we can observe only small part of total effect of one sign muons. On the basis of our gen- eral theory of cosmic ray meteorological effects with taking into account of negative soft muon acceleration and deceleration in the Earth atmosphere (in dependence of di- rection and intensity of electric field) we discuss the possibility of existing this effect in cosmic ray neutron component and made some rough estimations. REFERENCES: Dorman L.I. and Dorman I.V., 1995. "Cosmic-ray atmospheric electric field effects". Canadian J. of Physics, Vol. 73, pp. 440-443.

Using Web Server Logs to Track Users through the Electronic Forest

ERIC Educational Resources Information Center

Coombs, Karen A.

2005-01-01

This article analyzes server logs, providing helpful information in making decisions about Web-based services. The author indicates, as a result of analyzing server logs, several interesting things about the users' behavior were learned. The resulting findings are discussed in this article. Certain pages of the author's Web site, for instance, are…

The NMDB collaboration

NASA Astrophysics Data System (ADS)

Steigies, C. T.

2015-12-01

Since the International Geophysical Year (IGY) in 1957-58 cosmic rays areroutinely measured by many ground-based Neutron Monitors (NM) around theworld. The World Data Center for Cosmic Rays (WDCCR) was established as apart of this activity and is providing a database of cosmic-ray neutronobservations in unified formats. However, that standard data comprises onlyof one hour averages, whereas most NM stations have been enhanced at the endof the 20th century to provide data in one minute resolution or even better.This data was only available on the web-sites of the institutes operatingthe station, and every station invented their own data format for thehigh-resolution measurements. There were some efforts to collect data fromseveral stations, to make this data available on FTP servers, however noneof these efforts could provide real-time data for all stations.The EU FP7 project NMDB (real-time database for high-resolution NeutronMonitor measurements, http://nmdb.eu) was funded by the European Commission,and a new database was set up by several Neutron Monitor stations in Europeand Asia to store high-resolution data and to provide access to the data inreal-time (i.e. less than five minute delay). By storing the measurements ina database, a standard format for the high-resolution measurements isenforced. This database is complementary to the WDCCR, as it does not (yet)provide all historical data, but the creation of this effort has spurred anew collaboration between Neutron Monitor scientists worldwide, (new)stations have gone online (again), new projects are building on the resultsof NMDB, new users outside of the Cosmic Ray community are starting to useNM data for new applications like soil moisture measurements using cosmicrays. These applications are facilitated by the easy access to the data withthe http://nest.nmdb.eu interface that offers access to all NMDB data forall users.

Topology and geometry of the dark matter web: A multi-stream view

NASA Astrophysics Data System (ADS)

Ramachandra, Nesar S.; Shandarin, Sergei F.

2017-05-01

Topological connections in the single-streaming voids and multistreaming filaments and walls reveal a cosmic web structure different from traditional mass density fields. A single void structure not only percolates the multistream field in all the directions, but also occupies over 99 per cent of all the single-streaming regions. Sub-grid analyses on scales smaller than simulation resolution reveal tiny pockets of voids that are isolated by membranes of the structure. For the multistreaming excursion sets, the percolating structure is significantly thinner than the filaments in overdensity excursion approach. Hessian eigenvalues of the multistream field are used as local geometrical indicators of dark matter structures. Single-streaming regions have most of the zero eigenvalues. Parameter-free conditions on the eigenvalues in the multistream region may be used to delineate primitive geometries with concavities corresponding to filaments, walls and haloes.

A Measurement of the Average Longitudinal Development Profile of Cosmic Ray Air Showers from 1017.5eV to 1020eV by HiRes-II

NASA Astrophysics Data System (ADS)

Hughes, G.

Ultra High Energy Cosmic Rays (UHECRs) have an energy many times greater than that of particles accelerated in colliders. The Extended Air Showers (EAS) resulting from their interaction in the atmosphere give us the opportunity to study not only Cosmic Rays but also these extremely energetic cascades. A method to calculate the Average Longitudinal Shower profile has been applied to the High Resolution Fly's Eye Detector (HiRes) data. A complete detector simulation was used to throw CORSIKA (QGSJET) showers which are then analyzed using the same technique. The main features of the average showers are compared to the Monte Carlo as a function of energy. Systematic errors in the reconstruction of the profile are considered.

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

Attallah, R., E-mail: reda.attallah@univ-annaba.dz

High-energy cosmic-ray electrons reveal some remarkable spectral features, the most noteworthy of which is the rise in the positron fraction above 10 GeV. Due to strong energy loss during propagation, these particles can reach Earth only from nearby sources. Yet, the exact nature of these sources, which most likely manifest themselves in the observed anomalies, remains elusive. The many explanations put forward to resolve this case range from standard astrophysics to exotic physics. In this paper, we discuss the possible astrophysical origin of high-energy cosmic-ray electrons through a fully three-dimensional time-dependent Monte Carlo simulation. This approach, which takes advantage ofmore » the intrinsic random nature of cosmic-ray diffusive propagation, provides valuable information on the electron-by-electron fluctuations, making it particularly suitable for analyzing in depth the single-source scenario.« less

Using Web Server Logs in Evaluating Instructional Web Sites.

ERIC Educational Resources Information Center

Ingram, Albert L.

2000-01-01

Web server logs contain a great deal of information about who uses a Web site and how they use it. This article discusses the analysis of Web logs for instructional Web sites; reviews the data stored in most Web server logs; demonstrates what further information can be gleaned from the logs; and discusses analyzing that information for the…

Numerical analysis of beam with sinusoidally corrugated webs

NASA Astrophysics Data System (ADS)

Górecki, Marcin; Pieńko, Michał; Łagoda, GraŻyna

2018-01-01

The paper presents numerical tests results of the steel beam with sinusoidally corrugated web, which were performed in the Autodesk Algor Simulation Professional 2010. The analysis was preceded by laboratory tests including the beam's work under the influence of the four point bending as well as the study of material characteristics. Significant web's thickness and use of tools available in the software allowed to analyze the behavior of the plate girder as beam, and also to observe the occurrence of stresses in the characteristic element - the corrugated web. The stress distribution observed on the both web's surfaces was analyzed.

Oncogenomic portals for the visualization and analysis of genome-wide cancer data

PubMed Central

Klonowska, Katarzyna; Czubak, Karol; Wojciechowska, Marzena; Handschuh, Luiza; Zmienko, Agnieszka; Figlerowicz, Marek; Dams-Kozlowska, Hanna; Kozlowski, Piotr

2016-01-01

Somatically acquired genomic alterations that drive oncogenic cellular processes are of great scientific and clinical interest. Since the initiation of large-scale cancer genomic projects (e.g., the Cancer Genome Project, The Cancer Genome Atlas, and the International Cancer Genome Consortium cancer genome projects), a number of web-based portals have been created to facilitate access to multidimensional oncogenomic data and assist with the interpretation of the data. The portals provide the visualization of small-size mutations, copy number variations, methylation, and gene/protein expression data that can be correlated with the available clinical, epidemiological, and molecular features. Additionally, the portals enable to analyze the gathered data with the use of various user-friendly statistical tools. Herein, we present a highly illustrated review of seven portals, i.e., Tumorscape, UCSC Cancer Genomics Browser, ICGC Data Portal, COSMIC, cBioPortal, IntOGen, and BioProfiling.de. All of the selected portals are user-friendly and can be exploited by scientists from different cancer-associated fields, including those without bioinformatics background. It is expected that the use of the portals will contribute to a better understanding of cancer molecular etiology and will ultimately accelerate the translation of genomic knowledge into clinical practice. PMID:26484415

Oncogenomic portals for the visualization and analysis of genome-wide cancer data.

PubMed

Klonowska, Katarzyna; Czubak, Karol; Wojciechowska, Marzena; Handschuh, Luiza; Zmienko, Agnieszka; Figlerowicz, Marek; Dams-Kozlowska, Hanna; Kozlowski, Piotr

2016-01-05

Somatically acquired genomic alterations that drive oncogenic cellular processes are of great scientific and clinical interest. Since the initiation of large-scale cancer genomic projects (e.g., the Cancer Genome Project, The Cancer Genome Atlas, and the International Cancer Genome Consortium cancer genome projects), a number of web-based portals have been created to facilitate access to multidimensional oncogenomic data and assist with the interpretation of the data. The portals provide the visualization of small-size mutations, copy number variations, methylation, and gene/protein expression data that can be correlated with the available clinical, epidemiological, and molecular features. Additionally, the portals enable to analyze the gathered data with the use of various user-friendly statistical tools. Herein, we present a highly illustrated review of seven portals, i.e., Tumorscape, UCSC Cancer Genomics Browser, ICGC Data Portal, COSMIC, cBioPortal, IntOGen, and BioProfiling.de. All of the selected portals are user-friendly and can be exploited by scientists from different cancer-associated fields, including those without bioinformatics background. It is expected that the use of the portals will contribute to a better understanding of cancer molecular etiology and will ultimately accelerate the translation of genomic knowledge into clinical practice.

The WebQuest: constructing creative learning.

PubMed

Sanford, Julie; Townsend-Rocchiccioli, Judith; Trimm, Donna; Jacobs, Mike

2010-10-01

An exciting expansion of online educational opportunities is occurring in nursing. The use of a WebQuest as an inquiry-based learning activity can offer considerable opportunity for nurses to learn how to analyze and synthesize critical information. A WebQuest, as a constructivist, inquiry-oriented strategy, requires learners to use higher levels of thinking as a means to analyze and apply complex information, providing an exciting online teaching and learning strategy. A WebQuest is an inquiry-oriented lesson format in which most or all of the information learners work with comes from the web. This article provides an overview of the WebQuest as a teaching strategy and provides examples of its use. Copyright 2010, SLACK Incorporated.

The dependence of galaxy clustering on tidal environment in the Sloan Digital Sky Survey

NASA Astrophysics Data System (ADS)

Paranjape, Aseem; Hahn, Oliver; Sheth, Ravi K.

2018-06-01

The influence of the Cosmic Web on galaxy formation and evolution is of great observational and theoretical interest. We investigate whether the Cosmic Web leaves an imprint in the spatial clustering of galaxies in the Sloan Digital Sky Survey (SDSS), using the group catalogue of Yang et al. and tidal field estimates at ˜2 h-1 Mpc scales from the mass-tides-velocity data set of Wang et al. We use the tidal anisotropy α (Paranjape et al.) to characterize the tidal environment of groups, and measure the redshift-space 2-point correlation function (2pcf) of group positions and the luminosity- and colour-dependent clustering of group galaxies using samples segregated by α. We find that all the 2pcf measurements depend strongly on α, with factors of ˜20 between the large-scale 2pcf of objects in the most and least isotropic environments. To test whether these strong trends imply `beyond halo mass' effects for galaxy evolution, we compare our results with corresponding 2pcf measurements in mock catalogues constructed using a halo occupation distribution that uses only halo mass as an input. We find that this prescription qualitatively reproduces all observed trends, and also quantitatively matches many of the observed results. Although there are some statistically significant differences between our `halo mass only' mocks and the data - in the most and least isotropic environments - which deserve further investigation, our results suggest that if the tidal environment induces additional effects on galaxy properties other than those inherited from their host haloes, then these must be weak.

GALAXIES IN FILAMENTS HAVE MORE SATELLITES: THE INFLUENCE OF THE COSMIC WEB ON THE SATELLITE LUMINOSITY FUNCTION IN THE SDSS

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

Guo, Quan; Libeskind, N. I.; Tempel, E., E-mail: qguo@aip.de

We investigate whether the satellite luminosity function (LF) of primary galaxies identified in the Sloan Digital Sky Survey (SDSS) depends on whether the host galaxy is in a filament or not. Isolated primary galaxies are identified in the SDSS spectroscopic sample, and potential satellites (that are up to four magnitudes fainter than their hosts) are searched for in the much deeper photometric sample. Filaments are constructed from the galaxy distribution by the Bisous process. Isolated primary galaxies are divided into two subsamples: those in filaments and those not in filaments. We examine the stacked mean satellite LF of both themore » filament and nonfilament samples and find that, on average, the satellite LF of galaxies in filaments is significantly higher than those of galaxies not in filaments. The filamentary environment can increase the abundance of the brightest satellites (M {sub sat.} < M {sub prim.} + 2.0) by a factor of ∼2 compared with nonfilament isolated galaxies. This result is independent of the primary galaxy magnitude, although the satellite LF of galaxies in the faintest magnitude bin is too noisy to determine if such a dependence exists. Because our filaments are extracted from a spectroscopic flux-limited sample, we consider the possibility that the difference in satellite LF is due to a redshift, color, or environmental bias, finding these to be insufficient to explain our result. The dependence of the satellite LF on the cosmic web suggests that the filamentary environment may have a strong effect on the efficiency of galaxy formation.« less

Galaxies in Filaments have More Satellites: The Influence of the Cosmic Web on the Satellite Luminosity Function in the SDSS

NASA Astrophysics Data System (ADS)

Guo, Quan; Tempel, E.; Libeskind, N. I.

2015-02-01

We investigate whether the satellite luminosity function (LF) of primary galaxies identified in the Sloan Digital Sky Survey (SDSS) depends on whether the host galaxy is in a filament or not. Isolated primary galaxies are identified in the SDSS spectroscopic sample, and potential satellites (that are up to four magnitudes fainter than their hosts) are searched for in the much deeper photometric sample. Filaments are constructed from the galaxy distribution by the Bisous process. Isolated primary galaxies are divided into two subsamples: those in filaments and those not in filaments. We examine the stacked mean satellite LF of both the filament and nonfilament samples and find that, on average, the satellite LF of galaxies in filaments is significantly higher than those of galaxies not in filaments. The filamentary environment can increase the abundance of the brightest satellites (M sat. < M prim. + 2.0) by a factor of ~2 compared with nonfilament isolated galaxies. This result is independent of the primary galaxy magnitude, although the satellite LF of galaxies in the faintest magnitude bin is too noisy to determine if such a dependence exists. Because our filaments are extracted from a spectroscopic flux-limited sample, we consider the possibility that the difference in satellite LF is due to a redshift, color, or environmental bias, finding these to be insufficient to explain our result. The dependence of the satellite LF on the cosmic web suggests that the filamentary environment may have a strong effect on the efficiency of galaxy formation.

Weak-lensing detection of intracluster filaments with ground-based data

NASA Astrophysics Data System (ADS)

Maturi, Matteo; Merten, Julian

2013-11-01

According to the current standard model of cosmology, matter in the Universe arranges itself along a network of filamentary structure. These filaments connect the main nodes of this so-called "cosmic web", which are clusters of galaxies. Although its large-scale distribution is clearly characterized by numerical simulations, constraining the dark-matter content of the cosmic web in reality turns out to be difficult. The natural method of choice is gravitational lensing. However, the direct detection and mapping of the elusive filament signal is challenging and in this work we present two methods that are specifically tailored to achieve this task. A linear matched filter aims at detecting the smooth mass-component of filaments and is optimized to perform a shear decomposition that follows the anisotropic component of the lensing signal. Filaments clearly inherit this property due to their morphology. At the same time, the contamination arising from the central massive cluster is controlled in a natural way. The filament 1σ detection is of about κ ~ 0.01 - 0.005 according to the filter's template width and length, enabling the detection of structures beyond reach with other approaches. The second, complementary method seeks to detect the clumpy component of filaments. The detection is determined by the number density of subclump identifications in an area enclosing the potential filament, as was found within the observed field with the filter approach. We tested both methods against mocked observations based on realistic N-body simulations of filamentary structure and proved the feasibility of detecting filaments with ground-based data.

ZOMG - I. How the cosmic web inhibits halo growth and generates assembly bias

NASA Astrophysics Data System (ADS)

Borzyszkowski, Mikolaj; Porciani, Cristiano; Romano-Díaz, Emilio; Garaldi, Enrico

2017-07-01

The clustering of dark matter haloes with fixed mass depends on their formation history, an effect known as assembly bias. We use zoom N-body simulations to investigate the origin of this phenomenon. For each halo at redshift z = 0, we determine the time in which the physical volume containing its final mass becomes stable. We consider five examples for which this happens at z ˜ 1.5 and two that do not stabilize by z = 0. The zoom simulations show that early-collapsing haloes do not grow in mass at z = 0 while late-forming ones show a net inflow. The reason is that 'accreting' haloes are located at the nodes of a network of thin filaments feeding them. Conversely, each 'stalled' halo lies within a prominent filament that is thicker than the halo size. Infalling material from the surroundings becomes part of the filament while matter within it recedes from the halo. We conclude that assembly bias originates from quenching halo growth due to tidal forces following the formation of non-linear structures in the cosmic web, as previously conjectured in the literature. Also the internal dynamics of the haloes change: the velocity anisotropy profile is biased towards radial (tangential) orbits in accreting (stalled) haloes. Our findings reveal the cause of the yet unexplained dependence of halo clustering on the anisotropy. Finally, we extend the excursion-set theory to account for these effects. A simple criterion based on the ellipticity of the linear tidal field combined with the spherical-collapse model provides excellent predictions for both classes of haloes.

Symmetric Composite Laminate Stress Analysis

NASA Technical Reports Server (NTRS)

Wang, T.; Smolinski, K. F.; Gellin, S.

1985-01-01

It is demonstrated that COSMIC/NASTRAN may be used to analyze plate and shell structures made of symmetric composite laminates. Although general composite laminates cannot be analyzed using NASTRAN, the theoretical development presented herein indicates that the integrated constitutive laws of a symmetric composite laminate resemble those of a homogeneous anisotropic plate, which can be analyzed using NASTRAN. A detailed analysis procedure is presented, as well as an illustrative example.

Search for cosmic ray sources using muons detected by the MACRO experiment

NASA Astrophysics Data System (ADS)

Ambrosio, M.; Antolini, R.; Auriemma, G.; Bakari, D.; Baldini, A.; Barbarino, G. C.; Barish, B. C.; Battistoni, G.; Becherini, Y.; Bellotti, R.; Bemporad, C.; Bernardini, P.; Bilokon, H.; Bloise, C.; Bower, C.; Brigida, M.; Bussino, S.; Cafagna, F.; Calicchio, M.; Campana, D.; Carboni, M.; Caruso, R.; Cecchini, S.; Cei, F.; Chiarella, V.; Choudhary, B. C.; Coutu, S.; Cozzi, M.; de Cataldo, G.; Dekhissi, H.; de Marzo, C.; de Mitri, I.; Derkaoui, J.; de Vincenzi, M.; di Credico, A.; Erriquez, O.; Favuzzi, C.; Forti, C.; Fusco, P.; Giacomelli, G.; Giannini, G.; Giglietto, N.; Giorgini, M.; Grassi, M.; Grillo, A.; Guarino, F.; Gustavino, C.; Habig, A.; Hanson, K.; Heinz, R.; Iarocci, E.; Katsavounidis, E.; Katsavounidis, I.; Kearns, E.; Kim, H.; Kyriazopoulou, S.; Lamanna, E.; Lane, C.; Levin, D. S.; Lipari, P.; Longley, N. P.; Longo, M. J.; Loparco, F.; Maaroufi, F.; Mancarella, G.; Mandrioli, G.; Margiotta, A.; Marini, A.; Martello, D.; Marzari-Chiesa, A.; Mazziotta, M. N.; Michael, D. G.; Monacelli, P.; Montaruli, T.; Monteno, M.; Mufson, S.; Musser, J.; Nicolò, D.; Nolty, R.; Orth, C.; Osteria, G.; Palamara, O.; Patera, V.; Patrizii, L.; Pazzi, R.; Peck, C. W.; Perrone, L.; Petrera, S.; Pistilli, P.; Popa, V.; Rainò, A.; Reynoldson, J.; Ronga, F.; Rrhioua, A.; Satriano, C.; Scapparone, E.; Scholberg, K.; Sciubba, A.; Serra, P.; Sioli, M.; Sirri, G.; Sitta, M.; Spinelli, P.; Spinetti, M.; Spurio, M.; Steinberg, R.; Stone, J. L.; Sulak, L. R.; Surdo, A.; Tarlè, G.; Togo, V.; Vakili, M.; Walter, C. W.; Webb, R.

2003-03-01

The MACRO underground detector at Gran Sasso Laboratory recorded 60 million secondary cosmic ray muons from February 1989 until December 2000. Different techniques were used to analyze this sample in search for density excesses from astrophysical point-like sources. No evidence for DC excesses for any source in an all-sky survey is reported. In addition, searches for muon excess correlated with the known binary periods of Cygnus X-3 and Hercules X-1, and searches for statistically significant bursting episodes from known γ-ray sources are also proved negative.

Broad-band flared horn with low sidelobes. [applicable to cosmic background radiation measurement

NASA Technical Reports Server (NTRS)

Mather, J. C.

1981-01-01

A circular horn antenna flared like a trumpet is analyzed with the geometrical theory of diffraction and then tested experimentally. Sidelobes are found to be extremely low (-75 dB), in agreement with theory. Low sidelobe performance is predicted to be broad-band and to improve at higher frequencies. The full aperture of the tested horn is approximately 50 wavelengths. Suggestions for even better low sidelobe antennas are made. The applicability of this horn to the measurement of cosmic background radiation is noted.

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.

Exploring the potential of the cosmic-ray neutron method to measure interception storage dynamics

NASA Astrophysics Data System (ADS)

Jakobi, Jannis; Bogena, Heye; Huisman, Johan Alexander; Diekkrüger, Bernd; Vereecken, Harry

2017-04-01

Cosmic-ray neutron soil moisture probes are an emerging technology that relies on the negative correlation between near-surface fast neutron counts and soil moisture content. Hydrogen atoms in the soil, which are mainly present as water, moderate the secondary neutrons on the way back to the surface. Any application of this method needs to consider the sensitivity of the neutron counts to additional sources of hydrogen (e.g. above- and below-ground biomass, humidity of the lower atmosphere, lattice water of the soil minerals, organic matter and water in the litter layer, intercepted water in the canopy, and soil organic matter). In this study, we analyzed the effects of canopy-intercepted water on the cosmic-ray neutron counts. For this, an arable field cropped with sugar beet was instrumented with several cosmic-ray neutron probes and a wireless sensor network with more than 140 in-situ soil moisture sensors. Additionally rainfall interception was estimated using a new approach coupling throughfall measurements and leaf wetness sensors. The derived interception storage was used to correct for interception effects on cosmic ray neutrons to enhance soil water content prediction. Furthermore, the potential for a simultaneous prediction of above- and below-ground biomass, soil moisture and interception was tested.

Probing the BSM physics with CMB precision cosmology: an application to supersymmetry

NASA Astrophysics Data System (ADS)

Dalianis, Ioannis; Watanabe, Yuki

2018-02-01

The cosmic history before the BBN is highly determined by the physics that operates beyond the Standard Model (BSM) of particle physics and it is poorly constrained observationally. Ongoing and future precision measurements of the CMB observables can provide us with significant information about the pre-BBN era and hence possibly test the cosmological predictions of different BSM scenarios. Supersymmetry is a particularly motivated BSM theory and it is often the case that different superymmetry breaking schemes require different cosmic histories with specific reheating temperatures or low entropy production in order to be cosmologically viable. In this paper we quantify the effects of the possible alternative cosmic histories on the n s and r CMB observables assuming a generic non-thermal stage after cosmic inflation. We analyze TeV and especially multi-TeV super-symmetry breaking schemes assuming the neutralino and gravitino dark matter scenarios. We complement our analysis considering the Starobinsky R 2 inflation model to exemplify the improved CMB predictions that a unified description of the early universe cosmic evolution yields. Our analysis underlines the importance of the CMB precision measurements that can be viewed, to some extend, as complementary to the laboratory experimental searches for supersymmetry or other BSM theories.

Constraints on cosmic ray propagation in the galaxy

NASA Technical Reports Server (NTRS)

Cordes, James M.

1992-01-01

The goal was to derive a more detailed picture of magnetohydrodynamic turbulence in the interstellar medium and its effects on cosmic ray propagation. To do so, radio astronomical observations (scattering and Faraday rotation) were combined with knowledge of solar system spacecraft observations of MHD turbulence, simulations of wave propagation, and modeling of the galactic distribution to improve the knowledge. A more sophisticated model was developed for the galactic distribution of electron density turbulence. Faraday rotation measure data was analyzed to constrain magnetic field fluctuations in the ISM. VLBI observations were acquired of compact sources behind the supernova remnant CTA1. Simple calculations were made about the energies of the turbulence assuming a direct link between electron density and magnetic field variations. A simulation is outlined of cosmic ray propagation through the galaxy using the above results.

Kneelike Structure in the Spectrum of the Heavy Component of Cosmic Rays Observed with KASCADE-Grande

NASA Astrophysics Data System (ADS)

Apel, W. D.; Arteaga-Velázquez, J. C.; Bekk, K.; Bertaina, M.; Blümer, J.; Bozdog, H.; Brancus, I. M.; Buchholz, P.; Cantoni, E.; Chiavassa, A.; Cossavella, F.; Daumiller, K.; de Souza, V.; di Pierro, F.; Doll, P.; Engel, R.; Engler, J.; Finger, M.; Fuhrmann, D.; Ghia, P. L.; Gils, H. J.; Glasstetter, R.; Grupen, C.; Haungs, A.; Heck, D.; Hörandel, J. R.; Huber, D.; Huege, T.; Isar, P. G.; Kampert, K.-H.; Kang, D.; Klages, H. O.; Link, K.; Łuczak, P.; Ludwig, M.; Mathes, H. J.; Mayer, H. J.; Melissas, M.; Milke, J.; Mitrica, B.; Morello, C.; Navarra, G.; Oehlschläger, J.; Ostapchenko, S.; Over, S.; Palmieri, N.; Petcu, M.; Pierog, T.; Rebel, H.; Roth, M.; Schieler, H.; Schröder, F. G.; Sima, O.; Toma, G.; Trinchero, G. C.; Ulrich, H.; Weindl, A.; Wochele, J.; Wommer, M.; Zabierowski, J.

2011-10-01

We report the observation of a steepening in the cosmic ray energy spectrum of heavy primary particles at about 8×1016eV. This structure is also seen in the all-particle energy spectrum, but is less significant. Whereas the “knee” of the cosmic ray spectrum at 3-5×1015eV was assigned to light primary masses by the KASCADE experiment, the new structure found by the KASCADE-Grande experiment is caused by heavy primaries. The result is obtained by independent measurements of the charged particle and muon components of the secondary particles of extensive air showers in the primary energy range of 1016 to 1018eV. The data are analyzed on a single-event basis taking into account also the correlation of the two observables.

Cosmic censorship in Lovelock theory

NASA Astrophysics Data System (ADS)

Camanho, Xián O.; Edelstein, José D.

2013-11-01

In analyzing maximally symmetric Lovelock black holes with non-planar horizon topologies, many novel features have been observed. The existence of finite radius singularities, a mass gap in the black hole spectrum and solutions displaying multiple horizons are noteworthy examples. Naively, in all these cases, the appearance of naked singularities seems unavoidable, leading to the question of whether these theories are consistent gravity theories. We address this question and show that whenever the cosmic censorship conjecture is threaten, an instability generically shows up driving the system to a new configuration with presumably no naked singularities. Also, the same kind of instability shows up in the process of spherical black holes evaporation in these theories, suggesting a new phase for their decay. We find circumstantial evidence indicating that, contrary to many claims in the literature, the cosmic censorship hypothesis holds in Lovelock theory.

The galactic gamma-ray distribution: Implications for galactic structure and the radial cosmic ray gradient

NASA Technical Reports Server (NTRS)

Harding, A. K.; Stecker, F. W.

1984-01-01

The radial distribution of gamma ray emissivity in the Galaxy was derived from flux longitude profiles, using both the final SAS-2 results and the recently corrected COS-B results and analyzing the northern and southern galactic regions separately. The recent CO surveys of the Southern Hemisphere, were used in conjunction with the Northern Hemisphere data, to derive the radial distribution of cosmic rays on both sides of the galactic plane. In addition to the 5 kpc ring, there is evidence from the radial asymmetry for spiral features which are consistent with those derived from the distribution of bright HII regions. Positive evidence was also found for a strong increase in the cosmic ray flux in the inner Galaxy, particularly in the 5 kpc region in both halves of the plane.

Clinical cosmobiology: distribution of deaths during 180 months and cosmophysical activity. The Lithuanian study, 1990-2004. The role of cosmic rays.

PubMed

Stoupel, Elyiahu; Kalediene, Ramune; Petrauskiene, Jadvyga; Starkuviene, Skirmante; Abramson, Evgeny; Israelevich, Peter; Sulkes, Jaqueline

2007-01-01

The aim of this study is a next step of our previous, initial, publications--to explore the links between monthly death number (total, and for the major death causes and each gender) with levels of monthly cosmophysical activity in a long-term, big cohort observation. Death number during 180 consecutive months from the National Registry of Lithuania for years 1990-2004 were studied. A total of 630,205 deaths were analyzed (333,035 males). For comparison, monthly indices of solar activity, geomagnetic activity, and cosmic ray activity and year and month (1-12) of the study were used. The cosmophysical data were obtained from space research centers in the USA, Russia, and Finland. Statistics. Pearson correlation coefficients (r) and their probabilities (P) between compared parameters were calculated. A multivariate model of prediction was designed. It was a significant correlation between total monthly death number and indices of cosmic ray activity and, inverse, of solar activity; in men stronger than in women. Monthly geomagnetic activity was significantly correlated with traffic accidents, ischemic heart disease/stroke ratio, suicide victim number. Deaths from stroke, noncardiovascular causes, suicide, traffic accidents were related with cosmic ray activity and, inverse, with solar activity. Relationship of ischemic heart disease/stroke ratio to year of observation showed additional evidence for the growing role of stroke in cardiovascular mortality. Monthly death number is linked to cosmic ray activity, and inverse, to solar activity. Central place of stroke-related deaths in cardiovascular mortality is emerging. Geomagnetic activity, in monthly account, plays a relatively minor role. We presume that forces antagonistic to cosmic ray activity, like solar activity and geomagnetic activity, can prevent some negative biologic effects of cosmic ray.

Developing a Webcam-Based Data Logger to Analyze Cosmic Rays in a Cloud Chamber

NASA Astrophysics Data System (ADS)

Nealon, Kelly; Bellis, Matt

2015-04-01

Muons from secondary cosmic rays provide students with an opportunity to interact with a natural phenomenon that relies both on special relativity and fairly sophisticated particle physics knowledge. In many physics departments, undergraduate students set up a pair of scintillators in coincidence to measure the rate of these muons and in some cases, measure their angular dependence, but this requires specialized and potentially expensive equipment. We have spent the past year formalizing a design of a cloud chamber that relies not on dry ice, but Peltier thermoelectric coolers, that can be built for about one hundred dollars worth of equipment. With this design we can see the tracks left by cosmic rays, however to turn it into a useful undergraduate physics lab requires some sort of data logger. This poster details our efforts to use an off-the-shelf webcam to trigger on the change in image when a cosmic ray track appears in the chamber. We use this to estimate the rate and angular dependence and compare our results to other measurements. The successes and limitations of this approach will be discussed.

Discovering Authorities and Hubs in Different Topological Web Graph Structures.

ERIC Educational Resources Information Center

Meghabghab, George

2002-01-01

Discussion of citation analysis on the Web considers Web hyperlinks as a source to analyze citations. Topics include basic graph theory applied to Web pages, including matrices, linear algebra, and Web topology; and hubs and authorities, including a search technique called HITS (Hyperlink Induced Topic Search). (Author/LRW)

Dynamic Web Pages: Performance Impact on Web Servers.

ERIC Educational Resources Information Center

Kothari, Bhupesh; Claypool, Mark

2001-01-01

Discussion of Web servers and requests for dynamic pages focuses on experimentally measuring and analyzing the performance of the three dynamic Web page generation technologies: CGI, FastCGI, and Servlets. Develops a multivariate linear regression model and predicts Web server performance under some typical dynamic requests. (Author/LRW)

XII Multifrequency Behaviour of High Energy Cosmic Sources Workshop

NASA Astrophysics Data System (ADS)

2017-06-01

This is the twelfth edition of the series of Frascati Workshops on "Multifrequency Behaviour of High Energy Cosmic Sources" which is undoubtedly a largely accepted biennial meeting in which an updated experimental and theoretical panorama will be depicted. This edition comes at the 33rd anniversary of the first historical "multifrequency" workshop about "Multifrequency Behaviour of GalacticAccreting Sources", held in Vulcano in September 1984. This surely renders the Frascati Workshop Series the oldest among the many devoted to "Multifrequency Studies of Cosmic Sources". The study of the physics governing the cosmic sources will be the main goal of the workshop. A session devoted to the ongoing and next generation ground- and space-based experiments will give the actual prospects for the first decades of this millennium. The following items will be reviewed: Cosmology: Cosmic Background, Clusters of Galaxies Extragalactic Sources: Active Galaxies, Normal Galaxies Gamma-Rays Burst: Experiments versus Theories Galactic Sources: Pre-Main-Sequence and Main-Sequence Stars, Cataclysmic Variables and Novae, Supernovae and SNRs, X-Ray Binary Systems, Pulsars, Black Holes, Gamma-Ray Sources,Nucleosynthesis. The Astrophysics with the Ongoing and Future Experiments: Space-Based Experiments,Ground-Based Experiments. The workshop will include few 30-minute general review talks to introduce the current problems, and typically 20-minute talks discussing new experimental and theoretical results. A series of 20-minute talks will discuss the ongoing and planned ground- and space- based experiments. The cadence of the workshop is biennial. The participation will be only by invitation. All participants are kindly invited to attend the whole workshop. However, to keep alive the workshop it was decided that all presentations should be compulsorily given to the LOC, so that they can be inserted into the web page of the workshop. These presentations will form the basis for writing the papers to be published in the proceedings of the Frascati Workshop 2017 in electronic form by the Proceedings of Science (PoS-SISSA), after a peer referee process, and they will be freely available at once in the NASA- ADS. The editor of the proceedings will be Franco Giovannelli and Lola Sabau-Graziati.

CRIMEtoYHU: a new web tool to develop yeast-based functional assays for characterizing cancer-associated missense variants.

PubMed

Mercatanti, Alberto; Lodovichi, Samuele; Cervelli, Tiziana; Galli, Alvaro

2017-12-01

Evaluation of the functional impact of cancer-associated missense variants is more difficult than for protein-truncating mutations and consequently standard guidelines for the interpretation of sequence variants have been recently proposed. A number of algorithms and software products were developed to predict the impact of cancer-associated missense mutations on protein structure and function. Importantly, direct assessment of the variants using high-throughput functional assays using simple genetic systems can help in speeding up the functional evaluation of newly identified cancer-associated variants. We developed the web tool CRIMEtoYHU (CTY) to help geneticists in the evaluation of the functional impact of cancer-associated missense variants. Humans and the yeast Saccharomyces cerevisiae share thousands of protein-coding genes although they have diverged for a billion years. Therefore, yeast humanization can be helpful in deciphering the functional consequences of human genetic variants found in cancer and give information on the pathogenicity of missense variants. To humanize specific positions within yeast genes, human and yeast genes have to share functional homology. If a mutation in a specific residue is associated with a particular phenotype in humans, a similar substitution in the yeast counterpart may reveal its effect at the organism level. CTY simultaneously finds yeast homologous genes, identifies the corresponding variants and determines the transferability of human variants to yeast counterparts by assigning a reliability score (RS) that may be predictive for the validity of a functional assay. CTY analyzes newly identified mutations or retrieves mutations reported in the COSMIC database, provides information about the functional conservation between yeast and human and shows the mutation distribution in human genes. CTY analyzes also newly found mutations and aborts when no yeast homologue is found. Then, on the basis of the protein domain localization and functional conservation between yeast and human, the selected variants are ranked by the RS. The RS is assigned by an algorithm that computes functional data, type of mutation, chemistry of amino acid substitution and the degree of mutation transferability between human and yeast protein. Mutations giving a positive RS are highly transferable to yeast and, therefore, yeast functional assays will be more predictable. To validate the web application, we have analyzed 8078 cancer-associated variants located in 31 genes that have a yeast homologue. More than 50% of variants are transferable to yeast. Incidentally, 88% of all transferable mutations have a reliability score >0. Moreover, we analyzed by CTY 72 functionally validated missense variants located in yeast genes at positions corresponding to the human cancer-associated variants. All these variants gave a positive RS. To further validate CTY, we analyzed 3949 protein variants (with positive RS) by the predictive algorithm PROVEAN. This analysis shows that yeast-based functional assays will be more predictable for the variants with positive RS. We believe that CTY could be an important resource for the cancer research community by providing information concerning the functional impact of specific mutations, as well as for the design of functional assays useful for decision support in precision medicine. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Using a Web GIS Plate Tectonics Simulation to Promote Geospatial Thinking

ERIC Educational Resources Information Center

Bodzin, Alec M.; Anastasio, David; Sharif, Rajhida; Rutzmoser, Scott

2016-01-01

Learning with Web-based geographic information system (Web GIS) can promote geospatial thinking and analysis of georeferenced data. Web GIS can enable learners to analyze rich data sets to understand spatial relationships that are managed in georeferenced data visualizations. We developed a Web GIS plate tectonics simulation as a capstone learning…

Infrared complex refractive index of astrophysical ices exposed to cosmic rays simulated in the laboratory

NASA Astrophysics Data System (ADS)

Rocha, W. R. M.; Pilling, S.; de Barros, A. L. F.; Andrade, D. P. P.; Rothard, H.; Boduch, P.

2017-01-01

In the dense and cold regions of the interstellar medium, molecules can be adsorbed on to dust grains to form ice mantles. Once formed, these can be processed by ionizing radiation coming from the stellar or interstellar medium, leading to the formation of several new molecules in the ice. Among the different types of ionizing radiation, cosmic rays play an important role in solid-phase chemistry because of the large amount of energy deposited in the ices. The physicochemical changes induced by the energetic processing of astrophysical ices are recorded in a intrinsic parameter of the matter called the complex refractive index. In this paper, for the first time, we present a catalogue containing 39 complex refractive indices (n, k) in the infrared from 5000 to 600 cm-1 (2.0-16.6 μm) for 13 different water-containing ices processed in the laboratory by cosmic ray analogues. The calculation was performed using the NKABS - an acronym of the determination of N and K from absorbance data - code,which employs the Lambert-Beer and Kramers-Kronig equations to calculate the values of n and k. The results are also available at the following web site: http://www1.univap.br/gaa/nkabs-database/data.htm. As a test case, H2O:NH3:CO2:CH4 ice was employed in a radiative transfer simulation of a protoplanetary disc to show that these data are indispensable to reproduce the spectrum of ices containing young stellar objects.

Framing medical tourism: an examination of appeal, risk, convalescence, accreditation, and interactivity in medical tourism web sites.

PubMed

Mason, Alicia; Wright, Kevin B

2011-02-01

This exploratory study analyzed the content of medical tourism Web sites in an attempt to examine how they convey information about benefits and risks of medical procedures, how they frame credibility, and the degree to which these Web sites include interactive features for consumers. Drawing upon framing theory, the researchers content analyzed a sample of 66 medical tourism Web sites throughout the world. The results indicated that medical tourism Web sites largely promote the benefits of medical procedures while downplaying the risks, and relatively little information regarding the credibility of these services appears. In addition, the presentation of benefits/risks, credibility, and Web site interactivity were found to differ by region and type of facility. The authors discuss the implications of these findings concerning the framing of medical tourism Web site content, future directions for research, and limitations.

Real-Time Penetrating Particle Analyzer (PAN)

NASA Astrophysics Data System (ADS)

Wu, X.; Ambrosi, G.; Bertucci, B.

2018-02-01

The PAN can measure penetrating particles with great precision to study energetic particles, solar activities, and the origin and propagation of cosmic rays. The real-time monitoring of penetrating particles is crucial for deep space human travel.

Implementing a Cost Effectiveness Analyzer for Web-Supported Academic Instruction: A Campus Wide Analysis

ERIC Educational Resources Information Center

Cohen, Anat; Nachmias, Rafi

2009-01-01

This paper describes the implementation of a quantitative cost effectiveness analyzer for Web-supported academic instruction that was developed in Tel Aviv University during a long term study. The paper presents the cost effectiveness analysis of Tel Aviv University campus. Cost and benefit of 3,453 courses were analyzed, exemplifying campus-wide…

Solar tri-diurnal variation of cosmic rays in a wide range of rigidity

NASA Technical Reports Server (NTRS)

Mori, S.; Ueno, H.; Fujii, Z.; Morishita, I.; Nagashima, K.

1985-01-01

Solar tri-diurnal variations of cosmic rays have been analyzed in a wide range of rigidity, using data from neutron monitors, and the surface and underground muon telescopes for the period 1978-1983. The rigidity spectrum of the anisotropy in space is assumed to be of power-exponential type as (P/gamma P sub o) to the gamma exp (gamma-P/P sub o). By means of the best-fit method between the observed and the expected variations, it is obtained that the spectrum has a peak at P (=gamma P sub o) approx = 90 GV, where gamma=approx 3.0 and P sub o approx. 30 GV. The phase in space of the tri-diurnal variation is also obtained as 7.0 hr (15 hr and 23 hr LT), which is quite different from that of approx. 1 hr. arising from the axisymmetric distribution of cosmic rays with respect to the IMF.

Correlation of individual cosmic ray nuclei with the observation of light flashes by Apollo astronauts. [nuclear emulsion detector design and operation

NASA Technical Reports Server (NTRS)

Pinsky, L. S.; Osborne, W. Z.; Bailey, J. V.

1975-01-01

A nuclear emulsion detector known as the Apollo Light Flash Moving Emulsion Detector (ALFMED) was designed: (1) to record tracks of primary cosmic rays; (2) to provide time-of-passage information via a relative plate translation technique; (3) to provide particle trajectory information; and (4) to fit into a masklike device that could be located about the head and eyes of an astronaut. An ALFMED device was worn by an astronaut observing light flashes for 60 minutes on each of the last two Apollo missions. During the Apollo 17 experiment seventeen separate flashes were reported by the observer. With one-third of the total plate area completely analyzed, two definite correlations have been found between Z greater than 8 cosmic ray nuclei traversing an eye and the reports of visual sensations.

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

Vieira, H.S., E-mail: horacio.santana.vieira@hotmail.com; Centro de Ciências, Tecnologia e Saúde, Universidade Estadual da Paraíba, CEP 58233-000, Araruna, PB; Bezerra, V.B., E-mail: valdir@fisica.ufpb.br

Charged massive scalar fields are considered in the gravitational and electromagnetic field produced by a dyonic black hole with a cosmic string along its axis of symmetry. Exact solutions of both angular and radial parts of the covariant Klein–Gordon equation in this background are obtained, and are given in terms of the confluent Heun functions. The role of the presence of the cosmic string in these solutions is showed up. From the radial solution, we obtain the exact wave solutions near the exterior horizon of the black hole, and discuss the Hawking radiation spectrum and the energy flux. -- Highlights:more » •A cosmic string is introduced along the axis of symmetry of the dyonic black hole. •The covariant Klein–Gordon equation for a charged massive scalar field in this background is analyzed. •Both angular and radial parts are transformed to a confluent Heun equation. •The resulting Hawking radiation spectrum and the energy flux are obtained.« less

Search for Cross-Correlations of Ultrahigh-Energy Cosmic Rays with BL Lacertae Objects

NASA Astrophysics Data System (ADS)

Abbasi, R. U.; Abu-Zayyad, T.; Amann, J. F.; Archbold, G.; Belov, K.; Belz, J. W.; BenZvi, S.; Bergman, D. R.; Blake, S. A.; Boyer, J. H.; Burt, G. W.; Cao, Z.; Connolly, B. M.; Deng, W.; Fedorova, Y.; Findlay, J.; Finley, C. B.; Hanlon, W. F.; Hoffman, C. M.; Holzscheiter, M. H.; Hughes, G. A.; Hüntemeyer, P.; Jui, C. C. H.; Kim, K.; Kirn, M. A.; Knapp, B. C.; Loh, E. C.; Maestas, M. M.; Manago, N.; Mannel, E. J.; Marek, L. J.; Martens, K.; Matthews, J. A. J.; Matthews, J. N.; O'Neill, A.; Painter, C. A.; Perera, L.; Reil, K.; Riehle, R.; Roberts, M. D.; Rodriguez, D.; Sasaki, M.; Schnetzer, S. R.; Seman, M.; Sinnis, G.; Smith, J. D.; Snow, R.; Sokolsky, P.; Springer, R. W.; Stokes, B. T.; Thomas, J. R.; Thomas, S. B.; Thomson, G. B.; Tupa, D.; Westerhoff, S.; Wiencke, L. R.; Zech, A.; HIRES Collaboration

2006-01-01

Data taken in stereo mode by the High Resolution Fly's Eye (HiRes) air fluorescence experiment are analyzed to search for correlations between the arrival directions of ultrahigh-energy cosmic rays with the positions of BL Lacertae objects. Several previous claims of significant correlations between BL Lac objects and cosmic rays observed by other experiments are tested. These claims are not supported by the HiRes data. However, we verify a recent analysis of correlations between HiRes events and a subset of confirmed BL Lac objects from the 10th Veron Catalog, and we study this correlation in detail. Due to the a posteriori nature of the search, the significance level cannot be reliably estimated and the correlation must be tested independently before any claim can be made. We identify the precise hypotheses that will be tested with statistically independent data.

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.

Testing a Prototype for a New Cosmic Ray Particle Detector at the South Pole

NASA Astrophysics Data System (ADS)

Howell, R.; Rimsa, E.; Tharp, T.; Andeen, K.

2017-01-01

Cosmic ray research has grown rapidly in the past century, often using vacuum photomultiplier tubes (PMTs) to analyze the light produced by high-energy particles passing through scintillating material. Silicon photomultipliers (SiPMs) are now being recognized as a more efficient alternative to PMTs. Different types of photon events have been characterized using a SensL brand SiPM in combination with a QuarkNet Data Acquisition board. The goal of this study is to test the viability of the SiPM for a new generation surface detector at the South Pole.

A Compact Cosmic Ray Telescope using Silicon Photomultipliers for use in High Schools

NASA Astrophysics Data System (ADS)

Castro, Luis; Elizondo, Leonardo; Shelor, Mark; Cervantes, Omar; Fan, Sewan; Ritt, Stefan

2016-03-01

Over the years, the QuarkNet and the LBL Cosmic Ray Project have helped trained thousands of high school students and teachers to explore cosmic ray physics. To get high school students in the Salinas, CA area also excited about cosmic rays, we constructed a cosmic ray telescope as a physics outreach apparatus. Our apparatus includes a pair of plastic scintillators coupled to silicon photomultipliers (SiPM) and a coincidence circuit board. We designed and constructed custom circuit boards for mounting the SiPM detectors, the high voltage power supplies and coincidence AND circuit. The AND logic signals can be used for triggering data acquisition devices including an oscilloscope, a waveform digitizer or an Arduino microcontroller. To properly route the circuit wire traces, the circuit boards were layout in Eagle and fabricated in-house using a circuit board maker from LPKF LASER, model Protomat E33. We used a Raspberry Pi computer to control a fast waveform sampler, the DRS4 to digitize the SiPM signal waveforms. The CERN PAW software package was used to analyze the amplitude and time distributions of SiPM detector signals. At this conference, we present our SiPM experimental setup, circuit board fabrication procedures and the data analysis work flow. AIP Megger's Award, Dept. of Ed. Title V Grant PO31S090007.

Percolation analysis for cosmic web with discrete points

NASA Astrophysics Data System (ADS)

Zhang, Jiajun; Cheng, Dalong; Chu, Ming-Chung

2018-01-01

Percolation analysis has long been used to quantify the connectivity of the cosmic web. Most of the previous work is based on density fields on grids. By smoothing into fields, we lose information about galaxy properties like shape or luminosity. The lack of mathematical modeling also limits our understanding for the percolation analysis. To overcome these difficulties, we have studied percolation analysis based on discrete points. Using a friends-of-friends (FoF) algorithm, we generate the S -b b relation, between the fractional mass of the largest connected group (S ) and the FoF linking length (b b ). We propose a new model, the probability cloud cluster expansion theory to relate the S -b b relation with correlation functions. We show that the S -b b relation reflects a combination of all orders of correlation functions. Using N-body simulation, we find that the S -b b relation is robust against redshift distortion and incompleteness in observation. From the Bolshoi simulation, with halo abundance matching (HAM), we have generated a mock galaxy catalog. Good matching of the projected two-point correlation function with observation is confirmed. However, comparing the mock catalog with the latest galaxy catalog from Sloan Digital Sky Survey (SDSS) Data Release (DR)12, we have found significant differences in their S -b b relations. This indicates that the mock galaxy catalog cannot accurately retain higher-order correlation functions than the two-point correlation function, which reveals the limit of the HAM method. As a new measurement, the S -b b relation is applicable to a wide range of data types, fast to compute, and robust against redshift distortion and incompleteness and contains information of all orders of correlation functions.

The Cosmic Web around the Brightest Galaxies during the Epoch of Reionization

NASA Astrophysics Data System (ADS)

Ren, Keven; Trenti, Michele; Mutch, Simon J.

2018-03-01

The most luminous galaxies at high redshift are generally considered to be hosted in massive dark-matter halos of comparable number density, hence residing at the center of over-densities/protoclusters. We assess the validity of this assumption by investigating the clustering around the brightest galaxies populating the cosmic web at redshift z ∼ 8–9 through a combination of semi-analytic modeling and Monte Carlo simulations of mock Hubble Space Telescope WFC3 observations. The innovative aspect of our approach is the inclusion of a log-normal scatter parameter Σ in the galaxy luminosity versus halo mass relation, extending the conditional luminosity function framework extensively used at low redshift to high z. Our analysis shows that the larger the value of Σ, the less likely it is that the brightest source in a given volume is hosted in the most massive halo, and hence the weaker the overdensity of neighbors. We derive a minimum value of Σ as a function of redshift by considering stochasticity in the halo assembly times, which affects galaxy ages and star formation rates in our modeling. We show that Σmin(z) ∼ 0.15–0.3, with Σmin increasing with redshift as a consequence of shorter halo assembly periods at higher redshifts. Current observations (m AB ∼ 27) of the environment of spectroscopically confirmed bright sources at z > 7.5 do not show strong evidence of clustering and are consistent with our modeling predictions for Σ ≥ Σmin. Deeper future observations reaching m AB ∼ 28.2–29 would have the opportunity to clearly quantify the clustering strength and hence to constrain Σ, investigating the physical processes that drive star formation in the early universe.

Dust analysis on board the Destiny+ mission to 3200 Phaethon

NASA Astrophysics Data System (ADS)

Krüger, H.; Kobayashi, M.; Arai, T.; Srama, R.; Sarli, B. V.; Kimura, H.; Moragas-Klostermeyer, G.; Soja, R.; Altobelli, N.; Grün, E.

2017-09-01

The Japanese Destiny+ spacecraft will be launched to the active asteroid 3200 Phaethon in 2022. Among the proposed core payload is an in-situ dust instrument based on the Cassini Cosmic Dust Analyzer. We use the ESA Interplanetary Meteoroid Engineering Model (IMEM), to study detection conditions and fluences of interplanetary and interstellar dust with a dust analyzer on board Destiny+.

Unusual interactions above 100 TeV: A review of cosmic ray experiments with emulsion chambers

NASA Technical Reports Server (NTRS)

Yodh, D. B.

1977-01-01

A method is given for analyzing the space correlated collection of jets (gamma ray families) with energies greater than 100 TeV in Pb or Fe absorber sampled by photosensitive layers in an emulsion chamber. Events analyzed indicate large multiplicities of particles in the primary hadron-air interaction, and a marked absence of neutral pions.

Comparison of distributed acceleration and standard models of cosmic-ray transport

NASA Technical Reports Server (NTRS)

Letaw, J. R.; Silberberg, R.; Tsao, C. H.

1995-01-01

Recent cosmic-ray abundance measurements for elements in the range 3 less than or equal to Z less than or equal to 28 and energies 10 MeV/n less than or equal to E less than or equal to 1 TeV/n have been analyzed with computer transport modeling. About 500 elemental and isotopic measurements have been explored in this analysis. The transport code includes the effects of ionization losses, nuclear spallation reactions (including those of secondaries), all nuclear decay modes, stripping and attachment of electrons, escape from the Galaxy, weak reacceleration and solar modulation. Four models of reacceleration (with several submodels of various reacceleration strengths) were explored. A chi (exp 2) analysis show that the reacceleration models yield at least equally good fits to the data as the standard propagation model. However, with reacceleration, the ad hoc assumptions of the standard model regarding discontinuities in the energy dependence of the mean path length traversed by cosmic rays, and in the momentum spectrum of the cosmic-ray source spectrum are eliminated. Futhermore, the difficulty between rigidity dependent leakage and energy independent anisotropy below energies of 10(exp 14) eV is alleviated.

Cosmic Origins: A Traveling Science Exhibit and Education Program

NASA Astrophysics Data System (ADS)

Dusenbery, P. B.; Morrow, C. A.; Harold, J.

2003-12-01

The Space Science Institute of Boulder, Colorado, is developing a 3,000 square-foot traveling exhibition, called Cosmic Origins, which will bring origins-related research and discoveries to students and the American public. Cosmic Origins will have three interrelated exhibit areas: Star Formation, Planet Quest, and Search for Life. Exhibit visitors will explore the awesome events surrounding the birth of stars and planets; they will join scientists in the hunt for planets outside our solar system including those that may be in "habitable zones" around other stars; and finally they will be able to learn about the wide range of conditions for life on Earth and how scientists are looking for signs of life beyond Earth. Visitors will also learn about the tools scientists' use, such as space-based and ground-based telescopes, to improve our understanding of the cosmos. Exhibit content will address age-old questions that form the basis of NASA's Origins and Astrobiology programs: Where did we come from? Are we alone? In addition to the exhibit, our project will include workshops for educators and docents at host sites, as well as a public Web site that will use a virtual rendering of exhibit content. The exhibit's size will permit it to visit medium sized museums in underserved regions of the country. It will begin its 3-year tour to 9 host museums and science centers in early 2005. A second 3-year tour is also planned for 2008. The Association of Science-Technology Centers (ASTC) will manage the exhibit's national tour. Current partners in the Cosmic Origins project include ASTC, the Denver Museum of Nature and Science, Lawrence Hall of Science, NASA Astrobiology Institute, NASA missions (e.g. PlanetQuest, SIRTF, and Kepler), New York Hall of Science, the SETI Institute, and the Space Telescope Science Institute. The exhibition is supported by grants from NSF and NASA. This report will focus on the Planet Quest part of the exhibition.

Food and beverage brands that market to children and adolescents on the internet: a content analysis of branded web sites.

PubMed

Henry, Anna E; Story, Mary

2009-01-01

To identify food and beverage brand Web sites featuring designated children's areas, assess marketing techniques present on those industry Web sites, and determine nutritional quality of branded food items marketed to children. Systematic content analysis of food and beverage brand Web sites and nutrient analysis of food and beverages advertised on these Web sites. The World Wide Web. One-hundred thirty Internet Web sites of food and beverage brands with top media expenditures based on the America's Top 2000 Brands section of Brandweek magazine's annual "Superbrands" report. A standardized content analysis rating form to determine marketing techniques used on the food and beverage brand Web sites. Nutritional analysis of food brands was conducted. Of 130 Web sites analyzed, 48% featured designated children's areas. These Web sites featured a variety of Internet marketing techniques, including advergaming on 85% of the Web sites and interactive programs on 92% of the Web sites. Branded spokescharacters and tie-ins to other products were featured on the majority of the Web sites, as well. Few food brands (13%) with Web sites that market to children met the nutrition criteria set by the National Alliance for Nutrition and Activity. Nearly half of branded Web sites analyzed used designated children's areas to market food and beverages to children, 87% of which were of low nutritional quality. Nutrition professionals should advocate the use of advertising techniques to encourage healthful food choices for children.

Clusters of Galaxies and the Cosmic Web with Square Kilometre Array

NASA Astrophysics Data System (ADS)

Kale, Ruta; Dwarakanath, K. S.; Vir Lal, Dharam; Bagchi, Joydeep; Paul, Surajit; Malu, Siddharth; Datta, Abhirup; Parekh, Viral; Sharma, Prateek; Pandey-Pommier, Mamta

2016-12-01

The intra-cluster and inter-galactic media that pervade the large scale structure of the Universe are known to be magnetized at sub-micro Gauss to micro Gauss levels and to contain cosmic rays. The acceleration of cosmic rays and their evolution along with that of magnetic fields in these media is still not well understood. Diffuse radio sources of synchrotron origin associated with the Intra-Cluster Medium (ICM) such as radio halos, relics and mini-halos are direct probes of the underlying mechanisms of cosmic ray acceleration. Observations with radio telescopes such as the Giant Metrewave Radio Telescope, the Very Large Array and the Westerbork Synthesis Radio Telescope have led to the discoveries of about 80 such sources and allowed detailed studies in the frequency range 0.15-1.4 GHz of a few. These studies have revealed scaling relations between the thermal and non-thermal properties of clusters and favour the role of shocks in the formation of radio relics and of turbulent re-acceleration in the formation of radio halos and mini-halos. The radio halos are known to occur in merging clusters and mini-halos are detected in about half of the cool-core clusters. Due to the limitations of current radio telescopes, low mass galaxy clusters and galaxy groups remain unexplored as they are expected to contain much weaker radio sources. Distinguishing between the primary and the secondary models of cosmic ray acceleration mechanisms requires spectral measurements over a wide range of radio frequencies and with high sensitivity. Simulations have also predicted weak diffuse radio sources associated with filaments connecting galaxy clusters. The Square Kilometre Array (SKA) is a next generation radio telescope that will operate in the frequency range of 0.05-20 GHz with unprecedented sensitivities and resolutions. The expected detection limits of SKA will reveal a few hundred to thousand new radio halos, relics and mini-halos providing the first large and comprehensive samples for their study. The wide frequency coverage along with sensitivity to extended structures will be able to constrain the cosmic ray acceleration mechanisms. The higher frequency (>5 GHz) observations will be able to use the Sunyaev-Zel'dovich effect to probe the ICM pressure in addition to tracers such as lobes of head-tail radio sources. The SKA also opens prospects to detect the `off-state' or the lowest level of radio emission from the ICM predicted by the hadronic models and the turbulent re-acceleration models.

A WebGIS-based system for analyzing and visualizing air quality data for Shanghai Municipality

NASA Astrophysics Data System (ADS)

Wang, Manyi; Liu, Chaoshun; Gao, Wei

2014-10-01

An online visual analytical system based on Java Web and WebGIS for air quality data for Shanghai Municipality was designed and implemented to quantitatively analyze and qualitatively visualize air quality data. By analyzing the architecture of WebGIS and Java Web, we firstly designed the overall scheme for system architecture, then put forward the software and hardware environment and also determined the main function modules for the system. The visual system was ultimately established with the DIV + CSS layout method combined with JSP, JavaScript, and some other computer programming languages based on the Java programming environment. Moreover, Struts, Spring, and Hibernate frameworks (SSH) were integrated in the system for the purpose of easy maintenance and expansion. To provide mapping service and spatial analysis functions, we selected ArcGIS for Server as the GIS server. We also used Oracle database and ESRI file geodatabase to store spatial data and non-spatial data in order to ensure the data security. In addition, the response data from the Web server are resampled to implement rapid visualization through the browser. The experimental successes indicate that this system can quickly respond to user's requests, and efficiently return the accurate processing results.

Space weather influence on the agriculture technology and wheat prices in the medieval England (1259-1703) through cosmic ray/solar activity cycle variations

NASA Astrophysics Data System (ADS)

Dorman, L. I.; Pustil'Nik, L. A.; Yom Din, G.

2003-04-01

The database of Professor Rogers (1887), which includes wheat prices in England in the Middle Ages (1249-1703) was used to search for possible manifestations of solar activity and cosmic ray intensity variations. The main object of our statistical analysis is investigation of bursts of prices. Our study shows that bursts and troughs of wheat prices take place at extreme states (maximums or minimums) of solar activity cycles. We present a conceptual model of possible modes for sensitivity of wheat prices to weather conditions, caused by cosmic ray intensity solar cycle variations, and compare the expected price fluctuations with wheat price variations recorded in the Medieval England. We compared statistical properties of the intervals between price bursts with statistical properties of the intervals between extremes (minimums) of solar cycles during the years 1700-2000. The medians of both samples have the values of 11.00 and 10.7 years; standard deviations are 1.44 and 1.53 years for prices and for solar activity, respectively. The hypothesis that the frequency distributions are the same for both of the samples have significance level >95%. In the next step we analyzed direct links between wheat prices and cosmic ray cycle variations in the 17th Century, for which both wheat prices and cosmic ray intensity (derived from Be-10 isotope data) are available. We show that for all seven solar activity minimums (cosmic ray intensity maximums) the observed prices were higher than prices for the seven intervals of maximal solar activity (100% sign correlation). This result, combined with the conclusion of similarity of statistical properties of the price and solar activity extremes can be considered as direct evidence of a causal connection between wheat prices bursts and solar activity/cosmic ray intensity extremes.

Recent Progresses in Laboratory Astrophysics with Ames’ COSmIC Facility

NASA Astrophysics Data System (ADS)

Salama, Farid; Contreras, Cesar; Sciamma-O'Brien, Ella; Bejaoui, Salma

2016-06-01

We present and discuss the characteristics and the capabilities of the laboratory facility, COSmIC, that was developed at NASA Ames to generate, process and analyze interstellar, circumstellar and planetary analogs in the laboratory [1]. COSmIC stands for “Cosmic Simulation Chamber” and is dedicated to the study of neutral and ionized molecules and nano particles under the low temperature and high vacuum conditions that are required to simulate space environments. COSmIC integrates a variety of state-of-the-art instruments that allow forming, processing and monitoring simulated space conditions for planetary, circumstellar and interstellar materials in the laboratory. COSmIC is composed of a Pulsed Discharge Nozzle (PDN) expansion that generates a plasma in free supersonic jet expansion coupled to two high-sensitivity, complementary in situ diagnostics: a Cavity Ring Down Spectroscopy (CRDS) and laser induced fluorescence (LIF) systems for photonic detection and a Reflectron Time-Of-Flight Mass Spectrometer (ReTOF-MS) for mass detection [2].Recent laboratory results that were obtained using COSmIC will be presented, in particular the progress that has been achieved in the domain of the diffuse interstellar bands (DIBs) [3] and in monitoring, in the laboratory, the formation of dust grains and aerosols from their gas-phase molecular precursors in environments as varied as stellar/circumstellar outflows [4] and planetary atmospheres [5]. Plans for future, next generation, laboratory experiments on cosmic molecules and grains in the growing field of laboratory astrophysics will also be addressed as well as the implications of the current studies for astronomy.References: [1] Salama F., In Organic Matter in Space, IAU Symposium 251, Kwok & Sandford Eds.Cambridge University Press, Vol. 4, S251, p. 357 (2008) and references therein.[2] Ricketts C., Contreras C., Walker, R., Salama F., Int. J. Mass Spec, 300, 26 (2011)[3] Salama F., Galazutdinov G., Krelowski J., Biennier L., Beletsky Y., In-Ok Song, The Astrophys. J., 728, 154 (2011)[4] Cesar Contreras and Farid Salama, The Astrophys. J. Suppl. Ser., 208, 6 (2013)[5] Sciamma-O'Brien E., Ricketts C., and Salama F. Icarus, 243, 325 (2014)Acknowledgements: The authors acknowledge the support of NASA SMD.

Dusty Starbursts within a z=3 Large Scale Structure revealed by ALMA

NASA Astrophysics Data System (ADS)

Umehata, Hideki

The role of the large-scale structure is one of the most important theme in studying galaxy formation and evolution. However, it has been still mystery especially at z>2. On the basis of our ALMA 1.1 mm observations in a z ~ 3 protocluster field, it is suggested that submillimeter galaxies (SMGs) preferentially reside in the densest environment at z ~ 3. Furthermore we find a rich cluster of AGN-host SMGs at the core of the protocluster, combining with Chandra X-ray data. Our results indicate the vigorous star-formation and accelerated super massive black hole (SMBH) growth in the node of the cosmic web.

Advances in instrumentation at the W. M. Keck Observatory

NASA Astrophysics Data System (ADS)

Adkins, Sean M.; Armandroff, Taft; Lewis, Hilton; Martin, Chris; McLean, Ian S.; Rockosi, Constance; Wizinowich, Peter

2010-07-01

In this paper we describe both recently completed instrumentation projects and our current development efforts in the context of the Observatory's science driven strategic plan which seeks to address key questions in observational astronomy for extra-galactic, Galactic, and planetary science with both seeing limited capabilities and high angular resolution adaptive optics capabilities. This paper will review recently completed projects as well as new instruments in development including MOSFIRE, a near IR multi-object spectrograph nearing completion, a new seeing limited integral field spectrograph for the visible wavelength range called the Keck Cosmic Web Imager, and the Keck Next Generation Adaptive Optics facility and its first light science instrument DAVINCI.

Navigating the Web with a Typology of Corporate Uses.

ERIC Educational Resources Information Center

Hoger, Elizabeth A.; Cappel, James J.; Myerscough, Mark A.

1998-01-01

Describes a typology of business uses of the World Wide Web for electronic commerce. Gives examples of each type. Offers a sample assignment to show how the typology can be used in directing Web exploration, integrating the typology into an analytical assignment that analyzes a Web site using business communication concepts, and presenting the…

Recommendations for Benchmarking Web Site Usage among Academic Libraries.

ERIC Educational Resources Information Center

Hightower, Christy; Sih, Julie; Tilghman, Adam

1998-01-01

To help library directors and Web developers create a benchmarking program to compare statistics of academic Web sites, the authors analyzed the Web server log files of 14 university science and engineering libraries. Recommends a centralized voluntary reporting structure coordinated by the Association of Research Libraries (ARL) and a method for…

Graph Structure in Three National Academic Webs: Power Laws with Anomalies.

ERIC Educational Resources Information Center

Thelwall, Mike; Wilkinson, David

2003-01-01

Explains how the Web can be modeled as a mathematical graph and analyzes the graph structures of three national university publicly indexable Web sites from Australia, New Zealand, and the United Kingdom. Topics include commercial search engines and academic Web link research; method-analysis environment and data sets; and power laws. (LRW)

Observation of the large scale cosmic-ray anisotropy at TeV energies with the Milagro detector

NASA Astrophysics Data System (ADS)

Kolterman, Brian E.

Cosmic-rays with energies in the range of 1-100 TeV are nearly isotropic in their arrival directions due to interactions with randomly scattered inhomogeneities in the Galactic magnetic field. Observation of the large scale anisotropy in the arrival direction of these cosmic-rays is therefore a useful tool in constraining theoretical models of cosmic-ray propagation, probing the magnetic field structure in our interstellar neighborhood, as well as providing information about the distribution of sources. In this work results are presented of a harmonic analysis of the large scale cosmic-ray anisotropy as observed by the Milagro observatory. A two- dimensional display of the anisotropy projections in right ascension is generated by the fitting of three harmonics to 18 separate declination bands. Milagro is a water Cherenkov detector located at an elevation of 2630m in the Jemez mountains outside of Los Alamos, NM. With a live time > 90 and a large field-of-view (~2 sr), Milagro is an excellent instrument for measuring this anisotropy with high sensitivity at TeV energies. The analysis is conducted using a seven year data sample consisting of more than 95 billion events. A sidereal anisotropy is observed with a magnitude around 0.1% for cosmic-rays with a median energy of 6 TeV. The dominant feature in this data set is a deficit region of depth (-2.85±0.06 stat. ±0.08 syst.)×10 -3 in the direction of the Galactic North Pole with a range in declination of - 10 to 45 degrees and 150 to 225 degrees in right ascension. The anisotropy also shows evidence of a time dependence, with a steady increase in the magnitude of the signal in this region over the course of seven years. An analysis of the energy dependence of the anisotropy in this region is also presented showing possible deviation of the spectral index of the anisotropy signal from that of the nominal cosmic-ray background. The anisotropy of cosmic-rays in universal time is analyzed showing a dipole structure at the level of 3×10 -4 , consistent with the Compton-Getting effect expected due to the Earth's motion around the Sun through the cosmic-ray ether.

Multipolar anisotropy of E{sub 0} Greater-Than-Or-Slanted-Equal-To 10{sup 17} eV cosmic rays according to data of the Yakutsk array for studying extensive air showers

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

Glushkov, A. V., E-mail: a.v.glushkov@ikfia.ysn.ru

The results obtained by analyzing arrival directions for primary cosmic particles characterized by energies in the region E{sub 0} Greater-Than-Or-Slanted-Equal-To 10{sup 17} eV and zenith angles in the range {theta} Less-Than-Or-Slanted-Equal-To 60 Degree-Sign and detected at the Yakutsk array for studying extensive air showers (EASs) over the period spanning 1974 and 2009 are presented. It is shown that these events exhibit different anisotropies in different energy intervals.

On the Additional Absorption of Radio Emission from Discrete Cosmic Sources Under HF Modification of the Lower Ionosphere

NASA Astrophysics Data System (ADS)

Bezrodny, V. G.; Charkina, O. V.; Yampolski, Yu. M.

2015-12-01

The possibilities of modification of a weakly ionized plasma are investigated theoretically and experimentally within different electron density behavior models. The dependence of the additional absorption of radiation of discreet cosmic sources Cassiopeia A and Cygnus A in the artificially disturbed ionospheric D-region on the amplitude of heating signal during the special measuring campaigns of February and October 2008 has been analyzed. The ionosphere has been modified with using the world most powerful HAARP heater, Alaska, USA. The 64 beam riometer located in the immediate vicinity of the heater was used as the recording system.

Measurement of Neutron and Muon Fluxes 100~m Underground with the SciBath Detector

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

Garrison, Lance

2014-01-01

The SciBath detector is an 80 liter liquid scintillator detector read out by a three dimensional grid of 768 wavelength-shifting fibers. Initially conceived as a fine-grained charged particle detector for neutrino studies that could image charged particle tracks in all directions, it is also sensitive to fast neutrons (15-200 MeV). In fall of 2011 the apparatus performed a three month run to measure cosmic-induced muons and neutrons 100~meters underground in the FNAL MINOS near-detector area. Data from this run has been analyzed and resulted in measurements of the cosmic muon flux as \

Difference method to search for the anisotropy of primary cosmic radiation

NASA Astrophysics Data System (ADS)

Pavlyuchenko, V. P.; Martirosov, R. M.; Nikolskaya, N. M.; Erlykin, A. D.

2018-01-01

The original difference method used in the search for an anisotropy of primary cosmic radiation at the knee region of its energy spectrum is considered. Its methodical features and properties are analyzed. It is shown that this method, in which properties of particle fluxes (rather than an intensity) are investigated, is stable against random experimental errors and allows one to separate anomalies connected with the laboratory coordinate system from anomalies in the celestial coordinate system. The method uses the multiple scattering of charged particles in the magnetic fields of the Galaxy to study the whole celestial sphere, including the regions outside the line of sight of the installation.

Cosmic dust in the atmosphere and in the interplanetary space at 1 AU today and in the early solar system

NASA Technical Reports Server (NTRS)

Fechtig, H.

1973-01-01

A description of techniques used in recent experiments to detect and analyze cosmic dust and micrometeorites is given and the results both from the study of lunar crater statistics and from in situ measurements are reviewed. The results from lunar crater statistics show an agreement with the results obtained from in situ measurements in interplanetary space and derived from zodiacal light measurements. The near earth results show an enhancement in the flux numbers. This can be caused either by secondary lunar debris or by disintegration of low density fireballs in the outer atmosphere.

3D Tomography of a Mesa Using Cosmic Ray Muons Detected in an Underground Tunnel

NASA Astrophysics Data System (ADS)

Guardincerri, E.; Rowe, C. A.

2016-12-01

The LANL Mini Muon Tracker (MMT) is a muon tracking detector made of sealed aluminum drift tubes. The MMT was operated at four locations inside a tunnel under the Los Alamos town site mesa between November 2015 and February 2016 and it collected cosmic ray muons attenuated by the tunnel overburden. The data were analyzed and used to obtain a 3D tomographic image of the mesa and will be later combined with gravity data collected around the same location. We describe here the muon data taking and their analysis, and we show the resulting 3D image.

Multiply charged particles of the primary cosmic rays with energies greater than about 2 TeV

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

Ivanenko, I.P.; Grigorov, N.L.; Shestoperov, V.IA.

1986-08-01

Data on the energy spectra and charge composition of primary cosmic ray particles with energies greater than about 2 TeV are analyzed. The equipment on the Kosmos 1543 satellite used to obtain the data is described. Protons and alpha particles are detected, and the nuclei are separated into H, M, VH, and alpha groups. It is determined that the charge compositions of the primary nuclei with z greater than about 2 at energies greater than about 2 TeV compare well with data obtained at energies greater than about 1-10 GeV/nucleon. 8 references.

Acquiring geographical data with web harvesting

NASA Astrophysics Data System (ADS)

Dramowicz, K.

2016-04-01

Many websites contain very attractive and up to date geographical information. This information can be extracted, stored, analyzed and mapped using web harvesting techniques. Poorly organized data from websites are transformed with web harvesting into a more structured format, which can be stored in a database and analyzed. Almost 25% of web traffic is related to web harvesting, mostly while using search engines. This paper presents how to harvest geographic information from web documents using the free tool called the Beautiful Soup, one of the most commonly used Python libraries for pulling data from HTML and XML files. It is a relatively easy task to process one static HTML table. The more challenging task is to extract and save information from tables located in multiple and poorly organized websites. Legal and ethical aspects of web harvesting are discussed as well. The paper demonstrates two case studies. The first one shows how to extract various types of information about the Good Country Index from the multiple web pages, load it into one attribute table and map the results. The second case study shows how script tools and GIS can be used to extract information from one hundred thirty six websites about Nova Scotia wines. In a little more than three minutes a database containing one hundred and six liquor stores selling these wines is created. Then the availability and spatial distribution of various types of wines (by grape types, by wineries, and by liquor stores) are mapped and analyzed.

On the Inference of the Cosmic-ray Ionization Rate ζ from the HCO+-to-DCO+ Abundance Ratio: The Effect of Nuclear Spin

NASA Astrophysics Data System (ADS)

Shingledecker, Christopher N.; Bergner, Jennifer B.; Le Gal, Romane; Öberg, Karin I.; Hincelin, Ugo; Herbst, Eric

2016-10-01

The chemistry of dense interstellar regions was analyzed using a time-dependent gas-grain astrochemical simulation and a new chemical network that incorporates deuterated chemistry, taking into account nuclear spin states for the hydrogen chemistry and its deuterated isotopologues. With this new network, the utility of the [HCO+]/[DCO+] abundance ratio as a probe of the cosmic-ray ionization rate has been re-examined, with special attention paid to the effect of the initial value of the ortho-to-para ratio (OPR) of molecular hydrogen. After discussing the use of the probe for cold cores, we compare our results with previous theoretical and observational results for a molecular cloud close to the supernova remnant W51C, which is thought to have an enhanced cosmic-ray ionization rate ζ caused by the nearby γ-ray source. In addition, we attempt to use our approach to estimate the cosmic-ray ionization rate for L1174, a dense core with an embedded star. Beyond the previously known sensitivity of [HCO+]/[DCO+] to ζ, we demonstrate its additional dependence on the initial OPR and, secondarily, on the age of the source, its temperature, and its density. We conclude that the usefulness of the [HCO+]/[DCO+] abundance ratio in constraining the cosmic-ray ionization rate in dense regions increases with the age of the source and the ionization rate as the ratio becomes far less sensitive to the initial value of the OPR.

Hard X-ray irradiation of cosmic silicate analogs: structural evolution and astrophysical implications

NASA Astrophysics Data System (ADS)

Gavilan, L.; Jäger, C.; Simionovici, A.; Lemaire, J. L.; Sabri, T.; Foy, E.; Yagoubi, S.; Henning, T.; Salomon, D.; Martinez-Criado, G.

2016-03-01

Context. Protoplanetary disks, interstellar clouds, and active galactic nuclei contain X-ray-dominated regions. X-rays interact with the dust and gas present in such environments. While a few laboratory X-ray irradiation experiments have been performed on ices, X-ray irradiation experiments on bare cosmic dust analogs have been scarce up to now. Aims: Our goal is to study the effects of hard X-rays on cosmic dust analogs via in situ X-ray diffraction. By using a hard X-ray synchrotron nanobeam, we seek to simulate cumulative X-ray exposure on dust grains during their lifetime in these astrophysical environments and provide an upper limit on the effect of hard X-rays on dust grain structure. Methods: We prepared enstatite (MgSiO3) nanograins, which are analogs to cosmic silicates, via the melting-quenching technique. These amorphous grains were then annealed to obtain polycrystalline grains. These were characterized via scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) before irradiation. Powder samples were prepared in X-ray transparent substrates and were irradiated with hard X-rays nanobeams (29.4 keV) provided by beamline ID16B of the European Synchrotron Radiation Facility (Grenoble). X-ray diffraction images were recorded in transmission mode, and the ensuing diffractograms were analyzed as a function of the total X-ray exposure time. Results: We detected the amorphization of polycrystalline silicates embedded in an organic matrix after an accumulated X-ray exposure of 6.4 × 1027 eV cm-2. Pure crystalline silicate grains (without resin) do not exhibit amorphization. None of the amorphous silicate samples (pure and embedded in resin) underwent crystallization. We analyze the evolution of the polycrystalline sample embedded in an organic matrix as a function of X-ray exposure. Conclusions: Loss of diffraction peak intensity, peak broadening, and the disappearance of discrete spots and arcs reveal the amorphization of the resin embedded (originally polycrystalline) silicate sample. We explore the astrophysical implications of this laboratory result as an upper limit to the effect of X-rays on the structure of cosmic silicates.

Beyond Google: The Invisible Web in the Academic Library

ERIC Educational Resources Information Center

Devine, Jane; Egger-Sider, Francine

2004-01-01

This article analyzes the concept of the Invisible Web and its implication for academic librarianship. It offers a guide to tools that can be used to mine the Invisible Web and discusses the benefits of using the Invisible Web to promote interest in library services. In addition, the article includes an expanded definition, a literature review,…

The charged particle accelerators subsystems modeling

NASA Astrophysics Data System (ADS)

Averyanov, G. P.; Kobylyatskiy, A. V.

2017-01-01

Presented web-based resource for information support the engineering, science and education in Electrophysics, containing web-based tools for simulation subsystems charged particle accelerators. Formulated the development motivation of Web-Environment for Virtual Electrophysical Laboratories. Analyzes the trends of designs the dynamic web-environments for supporting of scientific research and E-learning, within the framework of Open Education concept.

Cosmological surveys with multi-object spectrographs

NASA Astrophysics Data System (ADS)

Colless, Matthew

2016-08-01

Multi-object spectroscopy has been a key technique contributing to the current era of `precision cosmology.' From the first exploratory surveys of the large-scale structure and evolution of the universe to the current generation of superbly detailed maps spanning a wide range of redshifts, multi-object spectroscopy has been a fundamentally important tool for mapping the rich structure of the cosmic web and extracting cosmological information of increasing variety and precision. This will continue to be true for the foreseeable future, as we seek to map the evolving geometry and structure of the universe over the full extent of cosmic history in order to obtain the most precise and comprehensive measurements of cosmological parameters. Here I briefly summarize the contributions that multi-object spectroscopy has made to cosmology so far, then review the major surveys and instruments currently in play and their prospects for pushing back the cosmological frontier. Finally, I examine some of the next generation of instruments and surveys to explore how the field will develop in coming years, with a particular focus on specialised multi-object spectrographs for cosmology and the capabilities of multi-object spectrographs on the new generation of extremely large telescopes.

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.

Nonstationary phenomena in cosmic rays with E 0 ≤ 1018 eV according to the data of the Yakutsk EAS array

NASA Astrophysics Data System (ADS)

Glushkov, A. V.; Pravdin, M. I.

2012-07-01

The energy spectrum of cosmic rays and the fraction of muons with the threshold 1.0secθ GeV in the total number of charged particles in extensive air showers with energy E 0 ≥ 1017 eV according to Yakutsk array data collected during 35 years of its continuous operation in 1978-2012 have been analyzed. It has been shown that these characteristics are noticeably different in different time periods. Before 1996, the integral intensity of the spectrum at E 0 = 1017 eV varied near one stable position and then began to increase. It increased by (45 ± 5)% in seven years and, then, began to decrease. This phenomenon was accompanied a similar change in the fraction of muons and was caused by a significant increase in the average weight of the chemical composition of cosmic rays after 1996 as compared to preceding years.

Cosmic ray spectrum and composition from three years of IceTop and IceCube

NASA Astrophysics Data System (ADS)

Rawlins, K.; IceCube Collaboration

2016-05-01

IceTop is the surface component of the IceCube Observatory, composed of frozen water tanks at the top of IceCube’s strings. Data from this detector can be analyzed in different ways with the goal of measuring cosmic ray spectrum and composition. The shower size S125 from IceTop alone can be used as a proxy for primary energy, and unfolded into an all-particle spectrum. In addition, S125 from the surface can be combined with high-energy muon energy loss information from the deep IceCube detector for those air showers which pass through both. Using these coincident events in a complementary analysis, both the spectrum and mass composition of primary cosmic rays can be extracted in parallel using a neural network. Both of these analyses have been performed on three years of IceTop and IceCube data. Both all-particle spectra as well as individual spectra for elemental groups are presented.

Search for space charge effects in the ICARUS T600 LAr-TPC

NASA Astrophysics Data System (ADS)

Torti, Marta

2016-11-01

Space charge in Liquid Argon Time Projection Chamber is due to the accumu- lation of positive ions, produced by ionizing tracks crossing the detector, which slowly flow toward the cathode. As a consequence, electric field distortions may arise, thus hindering the possibility to produce faithful 3D images of the ionizing events. The presence of space charge becomes relevant for large TPCs operating at surface or at shallow depths, where cosmic ray flux is high. These effects could interest the next phase of the ICARUS T600 detector, which will be deployed at shallow depths as a Far Detector for Short Baseline Neutrino experiment at FNAL dedicated to sterile neutrino searches. In 2001, the first ICARUS T600 module (T300) operated at surface in Pavia (Italy), recording cosmic ray data. In this work, a sample of cosmic muon tracks from the 2001 run was analyzed and results on space charge effects in LAr-TPCs are shown.

Vacuum Polarization by a Magnetic Flux Tube at Finite Temperature in the Cosmic String Space-Time

NASA Astrophysics Data System (ADS)

Spinelly, J.; Bezerra de Mello, E. R.

In this paper, we analyze the effect produced by the temperature in the vacuum polarization associated with a charged massless scalar field in the presence of a magnetic flux tube in the cosmic string space-time. Three different configurations of magnetic fields are taken into account: (i) a homogeneous field inside the tube, (ii) a field proportional to 1/r, and (iii) a cylindrical shell with δ-function. In these three cases, the axis of the infinitely long tube of radius R coincides with the cosmic string. Because of the complexity of this analysis in the region inside the tube, we consider the thermal effect in the region outside. In order to develop this analysis, we construct the thermal Green function associated with this system for the three above-mentioned situations considering points in the region outside the tube. We explicitly calculate, in the high-temperature limit, the thermal average of the field square and the energy-momentum tensor.

COSMIC monthly progress report

NASA Technical Reports Server (NTRS)

1994-01-01

Activities of the Computer Software Management and Information Center (COSMIC) are summarized for the month of May 1994. Tables showing the current inventory of programs available from COSMIC are presented and program processing and evaluation activities are summarized. Nine articles were prepared for publication in the NASA Tech Brief Journal. These articles (included in this report) describe the following software items: (1) WFI - Windowing System for Test and Simulation; (2) HZETRN - A Free Space Radiation Transport and Shielding Program; (3) COMGEN-BEM - Composite Model Generation-Boundary Element Method; (4) IDDS - Interactive Data Display System; (5) CET93/PC - Chemical Equilibrium with Transport Properties, 1993; (6) SDVIC - Sub-pixel Digital Video Image Correlation; (7) TRASYS - Thermal Radiation Analyzer System (HP9000 Series 700/800 Version without NASADIG); (8) NASADIG - NASA Device Independent Graphics Library, Version 6.0 (VAX VMS Version); and (9) NASADIG - NASA Device Independent Graphics Library, Version 6.0 (UNIX Version). Activities in the areas of marketing, customer service, benefits identification, maintenance and support, and dissemination are also described along with a budget summary.

Study of the Geoeffectiveness and Galactic Cosmic-Ray Response of VarSITI-ISEST Campaign Events in Solar Cycle 24

NASA Astrophysics Data System (ADS)

Aslam, O. P. M.; Badruddin

2017-09-01

We analyze and compare the geomagnetic and galactic cosmic-ray (GCR) response of selected solar events, particularly the campaign events of the group International Study of Earth-affecting Solar Transients (ISEST) of the program Variability of the Sun and Its Terrestrial Impact (VarSITI). These selected events correspond to Solar Cycle 24, and we identified various of their features during their near-Earth passage. We evaluated the hourly data of geomagnetic indices and ground-based neutron monitors and the concurrent data of interplanetary plasma and field parameters. We recognized distinct features of these events and solar wind parameters when the geomagnetic disturbance was at its peak and when the cosmic-ray intensity was most affected. We also discuss the similarities and differences in the geoeffectiveness and GCR response of the solar and interplanetary structures in the light of plasma and field variations and physical mechanism(s), which play a crucial role in influencing the geomagnetic activity and GCR intensity.

Cosmic Deuterium and Social Networking Software

NASA Astrophysics Data System (ADS)

Pasachoff, J. M.; Suer, T.-A.; Lubowich, D. A.; Glaisyer, T.

2006-08-01

For the education of newcomers to a scientific field and for the convenience of students and workers in the field, it is helpful to have all the basic scientific papers gathered. For the study of deuterium in the Universe, in 2004-5 we set up http://www.cosmicdeuterium.info with clickable links to all the historic and basic papers in the field and to many of the current papers. Cosmic deuterium is especially important because all deuterium in the Universe was formed in the epoch of nucleosynthesis in the first 1000 seconds after the Big Bang, so study of its relative abundance (D:H~1:100,000) gives us information about those first minutes of the Universe's life. Thus the understanding of cosmic deuterium is one of the pillars of modern cosmology, joining the cosmic expansion, the 3 degree cosmic background radiation, and the ripples in that background radiation. Studies of deuterium are also important for understanding Galactic chemical evolution, astrochemistry, interstellar processes, and planetary formation. Some papers had to be scanned while others are available at the Astrophysical Data System, adswww.harvard.edu, or to publishers' Websites. By 2006, social networking software (http:tinyurl.com/ zx5hk) had advanced with popular sites like facebook.com and MySpace.com; the Astrophysical Data System had even set up MyADS. Social tagging software sites like http://del.icio.us have made it easy to share sets of links to papers already available online. We have set up http://del.icio.us/deuterium to provide links to many of the papers on cosmicdeuterium.info, furthering previous del.icio.us work on /eclipses and /plutocharon. It is easy for the site owner to add links to a del.icio.us site; it takes merely clicking on a button on the browser screen once the site is opened and the desired link is viewed in a browser. Categorizing different topics by keywords allows subsets to be easily displayed. The opportunity to expose knowledge and build an ecosystem of web pages that use the functionality of a facebook-type application to capture knowledge collaboratively is considerable. Setting up such a system would marry one of the youngest isotopes with the latest software technologies.

Science on the Web: Secondary School Students' Navigation Patterns and Preferred Pages' Characteristics

NASA Astrophysics Data System (ADS)

Dimopoulos, Kostas; Asimakopoulos, Apostolos

2010-06-01

This study aims to explore navigation patterns and preferred pages' characteristics of ten secondary school students' searching the web for information about cloning. The students navigated the Web for as long as they wished in a context of minimum support of teaching staff. Their navigation patterns were analyzed using audit trail data software. The characteristics of their preferred Web pages were also analyzed using a scheme of analysis largely based on socio-linguistics and socio-semiotics approaches. Two distinct groups of students could be discerned. The first consisted of more competent students, who during their navigation visited fewer relevant pages, however of higher credibility and more specialized content. The second group consists of weaker students, who visited more pages, mainly of lower credibility and rather popularized content. Implications for designing educational web pages and teaching are discussed.

Analysis of microsize particulates

NASA Technical Reports Server (NTRS)

Blanchard, M. B.; Farlow, N. H.; Ferry, G. V.

1972-01-01

Unique methods for analyzing individual particles ranging in size from 0.01 to 1000 micrometers have been developed for investigation of nature of cosmic dust. Methods are applicable to particulate aerosols and contaminants characteristically encountered in studies of air pollution and in experiments designed to abate pollution.

Nuclear radiation analysis

NASA Technical Reports Server (NTRS)

Knies, R. J.; Byrn, N. R.; Smith, H. T.

1972-01-01

A study program of radiation shielding against the deleterious effects of nuclear radiation on man and equipment is reported. The methods used to analyze the radiation environment from bremsstrahlung photons are discussed along with the methods employed by transport code users. The theory and numerical methods used to solve transport of neutrons and gammas are described, and the neutron and cosmic fluxes that would be present on the gamma-ray telescope were analyzed.

Cosmic acceleration in non-flat f( T) cosmology

NASA Astrophysics Data System (ADS)

Capozziello, Salvatore; Luongo, Orlando; Pincak, Richard; Ravanpak, Arvin

2018-05-01

We study f( T) cosmological models inserting a non-vanishing spatial curvature and discuss its consequences on cosmological dynamics. To figure this out, a polynomial f( T) model and a double torsion model are considered. We first analyze those models with cosmic data, employing the recent surveys of Union 2.1, baryonic acoustic oscillation and cosmic microwave background measurements. We then emphasize that the two popular f( T) models enable the crossing of the phantom divide line due to dark torsion. Afterwards, we compute numerical bounds up to 3-σ confidence level, emphasizing the fact that Ω _{k0} turns out to be non-compatible with zero at least at 1σ . Moreover, we underline that, even increasing the accuracy, one cannot remove the degeneracy between our models and the Λ CDM paradigm. So that, we show that our treatments contain the concordance paradigm and we analyze the equation of state behaviors at different redshift domains. We also take into account gamma ray bursts and we describe the evolution of both the f( T) models with high redshift data. We calibrate the gamma ray burst measurements through small redshift surveys of data and we thus compare the main differences between non-flat and flat f( T) cosmology at different redshift ranges. We finally match the corresponding outcomes with small redshift bounds provided by cosmography. To do so, we analyze the deceleration parameters and their variations, proportional to the jerk term. Even though the two models well fit late-time data, we notice that the polynomial f( T) approach provides an effective de-Sitter phase, whereas the second f( T) framework shows analogous results compared with the Λ CDM predictions.

Utility of Web search query data in testing theoretical assumptions about mephedrone.

PubMed

Kapitány-Fövény, Máté; Demetrovics, Zsolt

2017-05-01

With growing access to the Internet, people who use drugs and traffickers started to obtain information about novel psychoactive substances (NPS) via online platforms. This paper aims to analyze whether a decreasing Web interest in formerly banned substances-cocaine, heroin, and MDMA-and the legislative status of mephedrone predict Web interest about this NPS. Google Trends was used to measure changes of Web interest on cocaine, heroin, MDMA, and mephedrone. Google search results for mephedrone within the same time frame were analyzed and categorized. Web interest about classic drugs found to be more persistent. Regarding geographical distribution, location of Web searches for heroin and cocaine was less centralized. Illicit status of mephedrone was a negative predictor of its Web search query rates. The connection between mephedrone-related Web search rates and legislative status of this substance was significantly mediated by ecstasy-related Web search queries, the number of documentaries, and forum/blog entries about mephedrone. The results might provide support for the hypothesis that mephedrone's popularity was highly correlated with its legal status as well as it functioned as a potential substitute for MDMA. Google Trends was found to be a useful tool for testing theoretical assumptions about NPS. Copyright © 2017 John Wiley & Sons, Ltd.

Four-dimensional characterization of a sheet-forming web

DOEpatents

Sari-Sarraf, Hamed; Goddard, James S.

2003-04-22

A method and apparatus are provided by which a sheet-forming web may be characterized in four dimensions. Light images of the web are recorded at a point adjacent the initial stage of the web, for example, near the headbox in a paperforming operation. The images are digitized, and the resulting data is processed by novel algorithms to provide a four-dimensional measurement of the web. The measurements include two-dimensional spatial information, the intensity profile of the web, and the depth profile of the web. These measurements can be used to characterize the web, predict its properties and monitor production events, and to analyze and quantify headbox flow dynamics.

Web data mining

NASA Astrophysics Data System (ADS)

Wibonele, Kasanda J.; Zhang, Yanqing

2002-03-01

A web data mining system using granular computing and ASP programming is proposed. This is a web based application, which allows web users to submit survey data for many different companies. This survey is a collection of questions that will help these companies develop and improve their business and customer service with their clients by analyzing survey data. This web application allows users to submit data anywhere. All the survey data is collected into a database for further analysis. An administrator of this web application can login to the system and view all the data submitted. This web application resides on a web server, and the database resides on the MS SQL server.

Analyses of cosmic ray induced-neutron based on spectrometers operated simultaneously at mid-latitude and Antarctica high-altitude stations during quiet solar activity

NASA Astrophysics Data System (ADS)

Hubert, G.

2016-10-01

In this paper are described a new neutron spectrometer which operate in the Concordia station (Antarctica, Dome C) since December 2015. This instrument complements a network including neutron spectrometers operating in the Pic-du-Midi and the Pico dos Dias. Thus, this work present an analysis of cosmic ray induced-neutron based on spectrometers operated simultaneously in the Pic-du-Midi and the Concordia stations during a quiet solar activity. The both high station platforms allow for investigating the long period dynamics to analyze the spectral variation and effects of local and seasonal changes, but also the short term dynamics during solar flare events. A first part is devoted to analyze the count rates, the spectrum and the neutron fluxes, implying cross-comparisons between data obtained in the both stations. In a second part, measurements analyses were reinforced by modeling based on simulations of atmospheric cascades according to primary spectra which only depend on the solar modulation potential.

The Implementation of a Cost Effectiveness Analyzer for Web-Supported Academic Instruction: An Example from Life Science

ERIC Educational Resources Information Center

Cohen, Anat; Nachmias, Rafi

2012-01-01

This paper describes implementation of a quantitative cost effectiveness analyzer for Web-supported academic instruction that was developed in our University. The paper presents the cost effectiveness analysis of one academic exemplary course in Life Science department and its introducing to the course lecturer for evaluation. The benefits and…

A Content Analysis of Themes That Emerge from School Principals' Web2.0 Conversations

ERIC Educational Resources Information Center

Manning, Rory

2011-01-01

The purpose of this qualitative study was to analyze the self initiated conversations held by school principals on web2.o platforms, such as blogs, through the lens of current leadership standards. The online writings of thirteen school principals were analyzed using grounded theory techniques (Strauss and Corbin, 1998) to elucidate emerging…

EasyFRAP-web: a web-based tool for the analysis of fluorescence recovery after photobleaching data.

PubMed

Koulouras, Grigorios; Panagopoulos, Andreas; Rapsomaniki, Maria A; Giakoumakis, Nickolaos N; Taraviras, Stavros; Lygerou, Zoi

2018-06-13

Understanding protein dynamics is crucial in order to elucidate protein function and interactions. Advances in modern microscopy facilitate the exploration of the mobility of fluorescently tagged proteins within living cells. Fluorescence recovery after photobleaching (FRAP) is an increasingly popular functional live-cell imaging technique which enables the study of the dynamic properties of proteins at a single-cell level. As an increasing number of labs generate FRAP datasets, there is a need for fast, interactive and user-friendly applications that analyze the resulting data. Here we present easyFRAP-web, a web application that simplifies the qualitative and quantitative analysis of FRAP datasets. EasyFRAP-web permits quick analysis of FRAP datasets through an intuitive web interface with interconnected analysis steps (experimental data assessment, different types of normalization and estimation of curve-derived quantitative parameters). In addition, easyFRAP-web provides dynamic and interactive data visualization and data and figure export for further analysis after every step. We test easyFRAP-web by analyzing FRAP datasets capturing the mobility of the cell cycle regulator Cdt2 in the presence and absence of DNA damage in cultured cells. We show that easyFRAP-web yields results consistent with previous studies and highlights cell-to-cell heterogeneity in the estimated kinetic parameters. EasyFRAP-web is platform-independent and is freely accessible at: https://easyfrap.vmnet.upatras.gr/.

Measurement of Cosmic Ray and Trapped Proton LET Spectra on the STS-95 HOST Mission

NASA Technical Reports Server (NTRS)

Stassinopoulos, E. G.; Barth, J. L.; Stauffer, C. A.

2017-01-01

This paper reports on in situ measurements of the Linear-Energy-Transfer (LET) spectra of galactic cosmic rays and their progeny and of trapped Van Allen belt protons as recorded by a Pulse Height Analyzer (PHA) radiation spectrometer which flew on the STS-95 DISCOVERY mission on the Hubble Orbital Systems Test (HOST) cradle. The Shuttle was launched on 29 October 1998 and had a mission duration of 8.5 days during the minimum phase of the solar activity cycle. The orbit of the STS-95 was about 550 km altitude and 28.5deg inclination. A close correlation was seen between radiation environment model predictions and the measurements of the PHA.

Effects of radiobiological uncertainty on shield design for a 60-day lunar mission

NASA Technical Reports Server (NTRS)

Wilson, John W.; Nealy, John E.; Schimmerling, Walter

1993-01-01

Some consequences of uncertainties in radiobiological risk due to galactic cosmic ray exposure are analyzed to determine their effect on engineering designs for a first lunar outpost - a 60-day mission. Quantitative estimates of shield mass requirements as a function of a radiobiological uncertainty factor are given for a simplified vehicle structure. The additional shield mass required for compensation is calculated as a function of the uncertainty in galactic cosmic ray exposure, and this mass is found to be as large as a factor of 3 for a lunar transfer vehicle. The additional cost resulting from this mass is also calculated. These cost estimates are then used to exemplify the cost-effectiveness of research.

Induced vacuum energy-momentum tensor in the background of a cosmic string

NASA Astrophysics Data System (ADS)

Sitenko, Yu A.; Vlasii, N. D.

2012-05-01

A massive scalar field is quantized in the background of a cosmic string which is generalized to a static flux-carrying codimension-2 brane in the locally flat multidimensional spacetime. We find that the finite energy-momentum tensor is induced in the vacuum. The dependence of the tensor components on the brane flux and tension, as well as on the coupling to the spacetime curvature scalar, is comprehensively analyzed. The tensor components are holomorphic functions of space dimension, decreasing exponentially with the distance from the brane. The case of the massless quantized scalar field is also considered, and the relevance of Bernoulli’s polynomials of even order for this case is discussed.

Cosmic ray sidereal diurnal variation of galactic origin observed by neutron monitors

NASA Technical Reports Server (NTRS)

Ishida, Y.; Nagashima, K.; Mori, S.; Morishita, I.

1985-01-01

Cosmic ray sidereal diurnal variations observed by neutron monitors are analyzed for the period 1961 to 1978, by adding 134 station years data to the previous paper (Nagashima, et al., 1983). Also the dependence of the sidereal variations on Sun's polar magnetic field polarity is examined for two periods; the period of negative polarity in the northern region, 1961 to 1969 and the period of positive polarity, 1970 to 1978. It is obtained that for the former period, the amplitude A=0.0203 + or 0.0020% and the phase phi=6.1 + or - 0.4 h LST and for the latter period, 0.0020% and phi=8.6 + or - 4 h LST, respectively.

Using Publishers' Web Sites for Reference Collection Development.

ERIC Educational Resources Information Center

Holmberg, Melissa

2000-01-01

Analyzes the ways publishers' Web sites can be used by librarians to locate additional science and technology reference materials which fall within budget constraints while meeting the needs of the patrons. Reviews specific publishers' Web sites to compare features and show how they differ. (Author/LRW)

THE MEASUREMENT OF RADIATION EXPOSURE OF ASTRONAUTS BY RADIOCHEMICAL TECHNIQUES October 6,1969 Through January 4, 1970

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

Brodzinski, R. L.; Rancitelli, L. A.; Haller, W. A.

1970-01-15

The urine and feces specimens from the Apollo 11 mission were analyzed for their radionuclide content. Estimates of cosmic radiation dose received by the astronauts were difficult to determine due to decay of the short-lived radionuclides during quarantine. The concentrations of {sup 7}Be, {sup 22}Na, {sup 40}K, {sup 59}Fe, {sup 60}Co, and {sup 137}Cs were determined. No {sup 147}Pm was observed in any of the samples. The concentrations of 16 major, minor, and trace elements were determined in fecal samples from Apollos 8 and 10. Large discrepancies between the excretion rates and normal dietary intakes were noted for cobalt, iron,more » tin , and potassium. An interpretation of the hazards these deviations may produce requires the determination of the elemental concentrations of the foodstuffs used during these missions. The fecal samples from the Apollo 11 mission were analyzed for glass fiber content. One anomalous sample was observed having a glass fiber content twofold greater than any previously measured specimen. A piece of the outer thermal coating of the Apollo 12 spacecraft was analyzed for cosmic-ray-induced radioactivity. Beryllium-7 was observed .« less

Impact of muon detection thresholds on the separability of primary cosmic rays

NASA Astrophysics Data System (ADS)

Müller, S.; Engel, R.; Pierog, T.; Roth, M.

2018-01-01

Knowledge of the mass composition of cosmic rays in the transition region of galactic to extragalactic cosmic rays is needed to discriminate different astrophysical models on their origin, acceleration, and propagation. An important observable to separate different mass groups of cosmic rays is the number of muons in extensive air showers. We performed a CORSIKA simulation study to analyze the impact of the detection threshold of muons on the separation quality of different primary cosmic rays in the energy region of the ankle. Using only the number of muons as the composition-sensitive observable, we find a clear dependence of the separation power on the detection threshold for ideal measurements. Although the number of detected muons increases when lowering the threshold, the discrimination power is reduced. If statistical fluctuations for muon detectors of limited size are taken into account, the threshold dependence remains qualitatively the same for small distances to the shower core but is reduced for large core distances. We interpret the impact of the detection threshold of muons on the composition sensitivity in terms of a change of the correlation of the number of muons nμ with the shower maximum Xmax as function of the muon energy as a result of the underlying hadronic interactions and the shower geometry. We further investigate the role of muons produced in a shower by photon-air interactions and conclude that, in addition to the effect of the nμ -Xmax correlation, the separability of primaries is reduced as a consequence of the presence of more muons from photonuclear reactions in proton than in iron showers.

ON THE INFERENCE OF THE COSMIC-RAY IONIZATION RATE ζ FROM THE HCO{sup +}-to-DCO{sup +} ABUNDANCE RATIO: THE EFFECT OF NUCLEAR SPIN

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

Shingledecker, Christopher N.; Le Gal, Romane; Hincelin, Ugo

2016-10-20

The chemistry of dense interstellar regions was analyzed using a time-dependent gas–grain astrochemical simulation and a new chemical network that incorporates deuterated chemistry, taking into account nuclear spin states for the hydrogen chemistry and its deuterated isotopologues. With this new network, the utility of the [HCO{sup +}]/[DCO{sup +}] abundance ratio as a probe of the cosmic-ray ionization rate has been re-examined, with special attention paid to the effect of the initial value of the ortho-to-para ratio (OPR) of molecular hydrogen. After discussing the use of the probe for cold cores, we compare our results with previous theoretical and observational resultsmore » for a molecular cloud close to the supernova remnant W51C, which is thought to have an enhanced cosmic-ray ionization rate ζ caused by the nearby γ -ray source. In addition, we attempt to use our approach to estimate the cosmic-ray ionization rate for L1174, a dense core with an embedded star. Beyond the previously known sensitivity of [HCO{sup +}]/[DCO{sup +}] to ζ , we demonstrate its additional dependence on the initial OPR and, secondarily, on the age of the source, its temperature, and its density. We conclude that the usefulness of the [HCO{sup +}]/[DCO{sup +}] abundance ratio in constraining the cosmic-ray ionization rate in dense regions increases with the age of the source and the ionization rate as the ratio becomes far less sensitive to the initial value of the OPR.« less

Space Weather Studies Using Ground-based Experimental Complex in Kazakhstan

NASA Astrophysics Data System (ADS)

Kryakunova, O.; Yakovets, A.; Monstein, C.; Nikolayevskiy, N.; Zhumabayev, B.; Gordienko, G.; Andreyev, A.; Malimbayev, A.; Levin, Yu.; Salikhov, N.; Sokolova, O.; Tsepakina, I.

2015-12-01

Kazakhstan ground-based experimental complex for space weather study is situated near Almaty. Results of space environment monitoring are accessible via Internet on the web-site of the Institute of Ionosphere (http://www.ionos.kz/?q=en/node/21) in real time. There is a complex database with hourly data of cosmic ray intensity, geomagnetic field intensity, and solar radio flux at 10.7 cm and 27.8 cm wavelengths. Several studies using those data are reported. They are an estimation of speed of a coronal mass ejection, a study of large scale traveling distrubances, an analysis of geomagnetically induced currents using the geomagnetic field data, and a solar energetic proton event on 27 January 2012.

Bolometers for millimeter-wave Cosmology

NASA Astrophysics Data System (ADS)

Bock, James J.

2002-05-01

Bolometers offer high sensitivity for observations of the cosmic microwave background, Sunyaev-Zel'Dovich effect in clusters, and far-infrared galaxies. Near background-limited performance may be realized even under the low background conditions available from a space-borne platform. We discuss the achieved performance of silicon nitride micromesh (`spider web') bolometers readout by NTD Ge thermistors. We are developing arrays of such bolometers coupled to single-mode feedhorns. CMB polarization may be studies using a new absorber geometry allowing simultaneous detection of both linear polarizations in a single feedhorn with two individual detectors. Finally we discuss a new bolometer architecture consisting of an array of slot antennae coupled to filters and bolometers via superconducting microstrip. .

The Majorana Parts Tracking Database

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

Abgrall, N.; Aguayo, E.; Avignone, F. T.

2015-04-01

The MAJORANA DEMONSTRATOR is an ultra-low background physics experiment searching for the neutrinoless double beta decay of 76Ge. The MAJORANA Parts Tracking Database is used to record the history of components used in the construction of the DEMONSTRATOR. Transportation, storage, and processes undergone by parts such as machining or cleaning are linked to part records. Tracking parts provides a great logistics benefit and an important quality assurance reference during construction. In addition, the location history of parts provides an estimate of their exposure to cosmic radiation. A web application for data entry and a radiation exposure calculator have been developedmore » as tools for achieving the extreme radiopurity required for this rare decay search.« less

Galaxy Transformations In The Cosmic Web

NASA Astrophysics Data System (ADS)

Jablonka, Pascale

2017-06-01

In this talk, I present a new survey, the Spatial Extended EDisCS Survey (SEEDisCS), that aims at understanding how clusters assemble and the level at which galaxies are preprocessed before falling on the cluster cores. SEEDisCS therefore focusses on the changes in galaxy properties along the large scale structures surrounding a couple of z 0.5 medium mass clusters, I first describe how spiral disc stellar populations are affected by the environment,and how we can get constraints on the timescale of star formation quenching. I then present new NOEMA and ALMA CO observations that trace the fate of the galaxy cold gas content along the infalling paths towards the cluster cores.

The World Wide Web and Technology Transfer at NASA Langley Research Center

NASA Technical Reports Server (NTRS)

Nelson, Michael L.; Bianco, David J.

1994-01-01

NASA Langley Research Center (LaRC) began using the World Wide Web (WWW) in the summer of 1993, becoming the first NASA installation to provide a Center-wide home page. This coincided with a reorganization of LaRC to provide a more concentrated focus on technology transfer to both aerospace and non-aerospace industry. Use of the WWW and NCSA Mosaic not only provides automated information dissemination, but also allows for the implementation, evolution and integration of many technology transfer applications. This paper describes several of these innovative applications, including the on-line presentation of the entire Technology Opportunities Showcase (TOPS), an industrial partnering showcase that exists on the Web long after the actual 3-day event ended. During its first year on the Web, LaRC also developed several WWW-based information repositories. The Langley Technical Report Server (LTRS), a technical paper delivery system with integrated searching and retrieval, has proved to be quite popular. The NASA Technical Report Server (NTRS), an outgrowth of LTRS, provides uniform access to many logically similar, yet physically distributed NASA report servers. WWW is also the foundation of the Langley Software Server (LSS), an experimental software distribution system which will distribute LaRC-developed software with the possible phase-out of NASA's COSMIC program. In addition to the more formal technology distribution projects, WWW has been successful in connecting people with technologies and people with other people. With the completion of the LaRC reorganization, the Technology Applications Group, charged with interfacing with non-aerospace companies, opened for business with a popular home page.

Cloud services for the Fermilab scientific stakeholders

DOE PAGES

Timm, S.; Garzoglio, G.; Mhashilkar, P.; ...

2015-12-23

As part of the Fermilab/KISTI cooperative research project, Fermilab has successfully run an experimental simulation workflow at scale on a federation of Amazon Web Services (AWS), FermiCloud, and local FermiGrid resources. We used the CernVM-FS (CVMFS) file system to deliver the application software. We established Squid caching servers in AWS as well, using the Shoal system to let each individual virtual machine find the closest squid server. We also developed an automatic virtual machine conversion system so that we could transition virtual machines made on FermiCloud to Amazon Web Services. We used this system to successfully run a cosmic raymore » simulation of the NOvA detector at Fermilab, making use of both AWS spot pricing and network bandwidth discounts to minimize the cost. On FermiCloud we also were able to run the workflow at the scale of 1000 virtual machines, using a private network routable inside of Fermilab. As a result, we present in detail the technological improvements that were used to make this work a reality.« less

Cloud services for the Fermilab scientific stakeholders

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

Timm, S.; Garzoglio, G.; Mhashilkar, P.

As part of the Fermilab/KISTI cooperative research project, Fermilab has successfully run an experimental simulation workflow at scale on a federation of Amazon Web Services (AWS), FermiCloud, and local FermiGrid resources. We used the CernVM-FS (CVMFS) file system to deliver the application software. We established Squid caching servers in AWS as well, using the Shoal system to let each individual virtual machine find the closest squid server. We also developed an automatic virtual machine conversion system so that we could transition virtual machines made on FermiCloud to Amazon Web Services. We used this system to successfully run a cosmic raymore » simulation of the NOvA detector at Fermilab, making use of both AWS spot pricing and network bandwidth discounts to minimize the cost. On FermiCloud we also were able to run the workflow at the scale of 1000 virtual machines, using a private network routable inside of Fermilab. As a result, we present in detail the technological improvements that were used to make this work a reality.« less

A SOAP Web Services Interface to ACE Data

NASA Astrophysics Data System (ADS)

Davis, A. J.; Hamell, G. R.

2005-05-01

Since early in 1998, NASA's Advanced Composition Explorer (ACE) spacecraft has provided continuous measurements of solar wind and energetic particle activity from L1, located approximately 0.01 AU sunward of Earth. ACE data from nine instruments are being used to measure and compare the elemental and isotopic composition of the solar corona, the nearby interstellar medium, and the Galaxy, and to study particle acceleration processes that occur in a wide range of environments. The spacecraft has enough fuel to stay in orbit about L1 until at least 2020. The ACE Science Center (ASC) provides access to ACE data, and performs level 1 and browse data processing for the science instruments. Available on-line are solar wind, solar energetic particle, and galactic cosmic ray intensity and composition data, as well as solar wind and magnetic field parameters on a variety of time scales. We describe our recent efforts to provide enhanced access to ACE data via a SOAP Web Services interface. The interface utilizes the Space Physics Archive Search and Extract (SPASE) dictionary, and will be compatible with emerging virtual observatories.

Topology and geometry of the dark matter web

NASA Astrophysics Data System (ADS)

Ramachandra, Nesar; Shandarin, Sergei

2017-01-01

Topological connections in the single-streaming voids and multi-streaming filaments and walls reveal a cosmic web structure different from traditional mass density fields. A single void structure not only percolates the multi-stream field in all the directions, but also occupies over 99 per cent of all the single-streaming regions. Sub-grid analyses on scales smaller than simulation resolution reveal tiny pockets of voids that are isolated by membranes of the structure. For the multi-streaming excursion sets, the percolating structure is much thinner than the filaments in over-density excursion approach. We also introduce, for the first time, a framework to detect dark matter haloes in multi-stream fields. Closed compact regions hosting local maxima of the multi-stream field are detected using local geometrical conditions and properties of the Lagrangian sub-manifold. All the halo particles are guaranteed to be completely outside void regions of the Universe. Majority of the halo candidates are embedded in the largest structure that percolates the entire volume. The University of Kansas FY 2017 Competition General Research Fund, GRF Award 2301155.

Surveying the Commons: Current Implementation of Information Commons Web sites

ERIC Educational Resources Information Center

Leeder, Christopher

2009-01-01

This study assessed the content of 72 academic library Information Commons (IC) Web sites using content analysis, quantitative assessment and qualitative surveys of site administrators to analyze current implementation by the academic library community. Results show that IC Web sites vary widely in content, design and functionality, with few…

The Web's Unelected Government.

ERIC Educational Resources Information Center

Garfinkel, Simson L.

1998-01-01

The World Wide Web Consortium--an organization based at the Massachusetts Institute of Technology (MIT) that has 275 corporate members and holds closed meetings--is the closest thing the Web has to a central authority; however, almost nobody outside the telecommunications industry understands what the consortium is. Analyzes the role this body may…

An Analysis of Academic Library Web Pages for Faculty

ERIC Educational Resources Information Center

Gardner, Susan J.; Juricek, John Eric; Xu, F. Grace

2008-01-01

Web sites are increasingly used by academic libraries to promote key services and collections to teaching faculty. This study analyzes the content, location, language, and technological features of fifty-four academic library Web pages designed especially for faculty to expose patterns in the development of these pages.

Academic Departments and Student Attitudes toward Different Dimensions of Web-based Education.

ERIC Educational Resources Information Center

Federico, Pat-Anthony

2001-01-01

Describes research at the Naval Postgraduate School that investigated student attitudes toward various aspects of Web-based instruction. Results of a survey, which were analyzed using a variety of multivariate and univariate statistical techniques, showed significantly different attitudes toward different dimensions of Web-based education…

Archetype-based conversion of EHR content models: pilot experience with a regional EHR system.

PubMed

Chen, Rong; Klein, Gunnar O; Sundvall, Erik; Karlsson, Daniel; Ahlfeldt, Hans

2009-07-01

Exchange of Electronic Health Record (EHR) data between systems from different suppliers is a major challenge. EHR communication based on archetype methodology has been developed by openEHR and CEN/ISO. The experience of using archetypes in deployed EHR systems is quite limited today. Currently deployed EHR systems with large user bases have their own proprietary way of representing clinical content using various models. This study was designed to investigate the feasibility of representing EHR content models from a regional EHR system as openEHR archetypes and inversely to convert archetypes to the proprietary format. The openEHR EHR Reference Model (RM) and Archetype Model (AM) specifications were used. The template model of the Cambio COSMIC, a regional EHR product from Sweden, was analyzed and compared to the openEHR RM and AM. This study was focused on the convertibility of the EHR semantic models. A semantic mapping between the openEHR RM/AM and the COSMIC template model was produced and used as the basis for developing prototype software that performs automated bi-directional conversion between openEHR archetypes and COSMIC templates. Automated bi-directional conversion between openEHR archetype format and COSMIC template format has been achieved. Several archetypes from the openEHR Clinical Knowledge Repository have been imported into COSMIC, preserving most of the structural and terminology related constraints. COSMIC templates from a large regional installation were successfully converted into the openEHR archetype format. The conversion from the COSMIC templates into archetype format preserves nearly all structural and semantic definitions of the original content models. A strategy of gradually adding archetype support to legacy EHR systems was formulated in order to allow sharing of clinical content models defined using different formats. The openEHR RM and AM are expressive enough to represent the existing clinical content models from the template based EHR system tested and legacy content models can automatically be converted to archetype format for sharing of knowledge. With some limitations, internationally available archetypes could be converted to the legacy EHR models. Archetype support can be added to legacy EHR systems in an incremental way allowing a migration path to interoperability based on standards.

Sexual information seeking on web search engines.

PubMed

Spink, Amanda; Koricich, Andrew; Jansen, B J; Cole, Charles

2004-02-01

Sexual information seeking is an important element within human information behavior. Seeking sexually related information on the Internet takes many forms and channels, including chat rooms discussions, accessing Websites or searching Web search engines for sexual materials. The study of sexual Web queries provides insight into sexually-related information-seeking behavior, of value to Web users and providers alike. We qualitatively analyzed queries from logs of 1,025,910 Alta Vista and AlltheWeb.com Web user queries from 2001. We compared the differences in sexually-related Web searching between Alta Vista and AlltheWeb.com users. Differences were found in session duration, query outcomes, and search term choices. Implications of the findings for sexual information seeking are discussed.

PATIKAweb: a Web interface for analyzing biological pathways through advanced querying and visualization.

PubMed

Dogrusoz, U; Erson, E Z; Giral, E; Demir, E; Babur, O; Cetintas, A; Colak, R

2006-02-01

Patikaweb provides a Web interface for retrieving and analyzing biological pathways in the Patika database, which contains data integrated from various prominent public pathway databases. It features a user-friendly interface, dynamic visualization and automated layout, advanced graph-theoretic queries for extracting biologically important phenomena, local persistence capability and exporting facilities to various pathway exchange formats.

Analyzing depression tendency of web posts using an event-driven depression tendency warning model.

PubMed

Tung, Chiaming; Lu, Wenhsiang

2016-01-01

The Internet has become a platform to express individual moods/feelings of daily life, where authors share their thoughts in web blogs, micro-blogs, forums, bulletin board systems or other media. In this work, we investigate text-mining technology to analyze and predict the depression tendency of web posts. In this paper, we defined depression factors, which include negative events, negative emotions, symptoms, and negative thoughts from web posts. We proposed an enhanced event extraction (E3) method to automatically extract negative event terms. In addition, we also proposed an event-driven depression tendency warning (EDDTW) model to predict the depression tendency of web bloggers or post authors by analyzing their posted articles. We compare the performance among the proposed EDDTW model, negative emotion evaluation (NEE) model, and the diagnostic and statistical manual of mental disorders-based depression tendency evaluation method. The EDDTW model obtains the best recall rate and F-measure at 0.668 and 0.624, respectively, while the diagnostic and statistical manual of mental disorders-based method achieves the best precision rate of 0.666. The main reason is that our enhanced event extraction method can increase recall rate by enlarging the negative event lexicon at the expense of precision. Our EDDTW model can also be used to track the change or trend of depression tendency for each post author. The depression tendency trend can help doctors to diagnose and even track depression of web post authors more efficiently. This paper presents an E3 method to automatically extract negative event terms in web posts. We also proposed a new EDDTW model to predict the depression tendency of web posts and possibly help bloggers or post authors to early detect major depressive disorder. Copyright © 2015 Elsevier B.V. All rights reserved.

The phase-space structure of nearby dark matter as constrained by the SDSS

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

Leclercq, Florent; Percival, Will; Jasche, Jens

Previous studies using numerical simulations have demonstrated that the shape of the cosmic web can be described by studying the Lagrangian displacement field. We extend these analyses, showing that it is now possible to perform a Lagrangian description of cosmic structure in the nearby Universe based on large-scale structure observations. Building upon recent Bayesian large-scale inference of initial conditions, we present a cosmographic analysis of the dark matter distribution and its evolution, referred to as the dark matter phase-space sheet, in the nearby universe as probed by the Sloan Digital Sky Survey main galaxy sample. We consider its stretchings andmore » foldings using a tetrahedral tessellation of the Lagrangian lattice. The method provides extremely accurate estimates of nearby density and velocity fields, even in regions of low galaxy density. It also measures the number of matter streams, and the deformation and parity reversals of fluid elements, which were previously thought inaccessible using observations. We illustrate the approach by showing the phase-space structure of known objects of the nearby Universe such as the Sloan Great Wall, the Coma cluster and the Boötes void. We dissect cosmic structures into four distinct components (voids, sheets, filaments, and clusters), using the Lagrangian classifiers DIVA, ORIGAMI, and a new scheme which we introduce and call LICH. Because these classifiers use information other than the sheer local density, identified structures explicitly carry physical information about their formation history. Accessing the phase-space structure of dark matter in galaxy surveys opens the way for new confrontations of observational data and theoretical models. We have made our data products publicly available.« less

The phase-space structure of nearby dark matter as constrained by the SDSS

NASA Astrophysics Data System (ADS)

Leclercq, Florent; Jasche, Jens; Lavaux, Guilhem; Wandelt, Benjamin; Percival, Will

2017-06-01

Previous studies using numerical simulations have demonstrated that the shape of the cosmic web can be described by studying the Lagrangian displacement field. We extend these analyses, showing that it is now possible to perform a Lagrangian description of cosmic structure in the nearby Universe based on large-scale structure observations. Building upon recent Bayesian large-scale inference of initial conditions, we present a cosmographic analysis of the dark matter distribution and its evolution, referred to as the dark matter phase-space sheet, in the nearby universe as probed by the Sloan Digital Sky Survey main galaxy sample. We consider its stretchings and foldings using a tetrahedral tessellation of the Lagrangian lattice. The method provides extremely accurate estimates of nearby density and velocity fields, even in regions of low galaxy density. It also measures the number of matter streams, and the deformation and parity reversals of fluid elements, which were previously thought inaccessible using observations. We illustrate the approach by showing the phase-space structure of known objects of the nearby Universe such as the Sloan Great Wall, the Coma cluster and the Boötes void. We dissect cosmic structures into four distinct components (voids, sheets, filaments, and clusters), using the Lagrangian classifiers DIVA, ORIGAMI, and a new scheme which we introduce and call LICH. Because these classifiers use information other than the sheer local density, identified structures explicitly carry physical information about their formation history. Accessing the phase-space structure of dark matter in galaxy surveys opens the way for new confrontations of observational data and theoretical models. We have made our data products publicly available.

The MARIACHI Project: Mixed Apparatus for Radio Investigation of Atmospheric Cosmic Rays of High Ionization

NASA Astrophysics Data System (ADS)

Inglis, M. D.; Takai, H.; Warasia, R.; Sundermier, J.

2005-12-01

Extreme Energy Cosmic Rays are nuclei that have been accelerated to kinetic energies in excess of 1020 eV. Where do they come from? How are they produced? Are they survivors of the early universe? Are they remnants of supernovas? MARIACHI, a unique collaboration between scientists, physics teachers and students, is an innovative technique that allows us to detect and study them. The Experiment MARIACHI is a unique research experiment that seeks the detection of extreme energy cosmic rays (EECRs), with E >1020 eV. It is an exciting project with many aspects: Research: It investigates an unconventional way of detecting EECRs based upon a method successfully used to detect meteors entering the upper atmosphere. The method was developed by planetary astronomers listening to radio signals reflected off the ionization trail. MARIACHI seeks to listen to TV signals reflected off the ionization trail of an EECR. The unique experiment topology will also permit the study of meteors, exotic forms of lightning, and atmospheric science. Computing and Technology: It uses radio detection stations, along with mini shower arrays hooked up to GPS clocks. Teachers and students build the arrays. It implements the Internet and the GRID as means of communication, data transfer, data processing, and for hosting a public educational outreach web site. Outreach and Education: It is an open research project with the active participation of a wide audience of astronomers, physicists, college professors, high school teachers and students. Groups representing high schools, community colleges and universities all collaborate in the project. The excitement of a real experiment motivates the science and technology classroom, and incorporates several high school physical science topics along with material from other disciplines such as astronomy, electronics, radio, optics.

Differential cosmic expansion and the Hubble flow anisotropy

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

Bolejko, Krzysztof; Nazer, M. Ahsan; Wiltshire, David L., E-mail: bolejko@physics.usyd.edu.au, E-mail: ahsan.nazer@canterbury.ac.nz, E-mail: david.wiltshire@canterbury.ac.nz

2016-06-01

The Universe on scales 10–100 h {sup −1}Mpc is dominated by a cosmic web of voids, filaments, sheets and knots of galaxy clusters. These structures participate differently in the global expansion of the Universe: from non-expanding clusters to the above average expansion rate of voids. In this paper we characterize Hubble expansion anisotropies in the COMPOSITE sample of 4534 galaxies and clusters. We concentrate on the dipole and quadrupole in the rest frame of the Local Group. These both have statistically significant amplitudes. These anisotropies, and their redshift dependence, cannot be explained solely by a boost of the Local Groupmore » in the Friedmann-Lemaitre-Robertson-Walker (FLRW) model which expands isotropically in the rest frame of the cosmic microwave background (CMB) radiation. We simulate the local expansion of the Universe with inhomogeneous Szekeres solutions, which match the standard FLRW model on ∼> 100 h {sup −1}Mpc scales but exhibit nonkinematic relativistic differential expansion on small scales. We restrict models to be consistent with observed CMB temperature anisotropies, while simultaneously fitting the redshift variation of the Hubble expansion dipole. We include features to account for both the Local Void and the 'Great Attractor'. While this naturally accounts for the Hubble expansion and CMB dipoles, the simulated quadrupoles are smaller than observed. Further refinement to incorporate additional structures may improve this. This would enable a test of the hypothesis that some large angle CMB anomalies result from failing to treat the relativistic differential expansion of the background geometry; a natural feature of solutions to Einstein's equations not included in the current standard model of cosmology.« less

Association of time of occurrence of electrical heart storms with environmental physical activity.

PubMed

Stoupel, Eliiyahu; Kusniec, Jairo; Golovchiner, Gregory; Abramson, Evgeny; Kadmon, Udi; Strasberg, Boris

2014-08-01

Many publications in recent decades have reported a temporal link between medical events and environmental physical activity. The aim of this study was to analyze the time of occurrence of electrical heart storms against levels of cosmological parameters. The sample included 82 patients (71 male) with ischemic cardiomyopathy treated with an implantable cardioverter defibrillator at a tertiary medical center in 1999-2012 (5,114 days). The time of occurrence of all electrical heart storms, defined as three or more events of ventricular tachycardia or ventricular fibrillation daily, was recorded from the defibrillator devices. Findings were analyzed against data on solar, geomagnetic, and cosmic ray (neutron) activity for the same time period obtained from space institutions in the United States and Russia. Electrical storms occurred in all months of the year, with a slight decrease in July, August, and September. Most events took place on days with lower-than-average levels of solar and geomagnetic activity and higher-than-average levels of cosmic ray (neutron) activity. There was a significant difference in mean daily cosmic ray activity between the whole observation period and the days of electrical storm activity (P = 0.0001). These data extend earlier findings on the association of the timing of cardiac events and space weather parameters to the most dangerous form of cardiac arrhythmia-electric storms. Further studies are needed to delineate the pathogenetic mechanism underlying this association. ©2014 Wiley Periodicals, Inc.

A Pilot Study of the Interface Design of Cross-Cultural Web Sites through Usability Testing of Multilanguage Web Sites and Determining the Preferences of Taiwanese and American Users

ERIC Educational Resources Information Center

Ku, David Tawei; Chang, Chia-Chi

2014-01-01

By conducting usability testing on a multilanguage Web site, this study analyzed the cultural differences between Taiwanese and American users in the performance of assigned tasks. To provide feasible insight into cross-cultural Web site design, Microsoft Office Online (MOO) that supports both traditional Chinese and English and contains an almost…

Illuminating the Background: Topics in Cosmic Microwave Background Polarization Research

NASA Astrophysics Data System (ADS)

Miller, Nathan J.

The cosmic microwave background provides a wealth of information about the origin and history of the universe. The statistics of the anisotropy and the polarization of the cosmic microwave background, among other things, can tell us about the distribution of matter, the redshift of reionization, and the nature of the primordial uctuations. From the lensing of cosmic microwave background due to intervening matter, we can extract information about neutrinos and the equation of state of dark energy. A measurement of the large angular scale B-mode polarization has been called the "smoking gun" of in ation, a theory that describes a possible early rapid expansion of the universe. The focus of current experiments is to measure this B-mode polarization, while several experiments, such as POLARBEAR, are also looking to measure the lensing of the cosmic microwave background. This dissertation will discuss several different topics in cosmic microwave background polarization research. I will make predictions for future experiments and I will also show analysis for two current experiments, POLARBEAR and BICEP. I will show how beam systematics affect the measurement of cosmological parameters and how well we must limit these systematics in order to get unbiased constraints on cosmological parameters for future experiments. I will discuss a novel way of using the temperature-polarization cross correlation to constrain the amount of inflationary gravitational waves. Through Markov Chain Monte Carlo methods, I will determine how well future experiments will be able to constrain the neutrino masses and their degeneracy parameters. I will show results from current data analysis and calibration being done on the Cedar Flat deployment for the POLARBEAR experiment which is currently being constructed in the Atacama desert in Chile. Finally, I will analyze the claim of detection of cosmological birefringence in the BICEP data and show that there is reason to believe it is due to systematic effects in the data.

The quality of mental health information commonly searched for on the Internet.

PubMed

Grohol, John M; Slimowicz, Joseph; Granda, Rebecca

2014-04-01

Previous research has reviewed the quality of online information related to specific mental disorders. Yet, no comprehensive study has been conducted on the overall quality of mental health information searched for online. This study examined the first 20 search results of two popular search engines-Google and Bing-for 11 common mental health terms. They were analyzed using the DISCERN instrument, an adaptation of the Depression Website Content Checklist (ADWCC), Flesch Reading Ease and Flesch-Kincaid Grade Level readability measures, HONCode badge display, and commercial status, resulting in an analysis of 440 web pages. Quality of Web site results varied based on type of disorder examined, with higher quality Web sites found for schizophrenia, bipolar disorder, and dysthymia, and lower quality ratings for phobia, anxiety, and panic disorder Web sites. Of the total Web sites analyzed, 67.5% had good or better quality content. Nearly one-third of the search results produced Web sites from three entities: WebMD, Wikipedia, and the Mayo Clinic. The mean Flesch Reading Ease score was 41.21, and the mean Flesch-Kincaid Grade Level score was 11.68. The presence of the HONCode badge and noncommercial status was found to have a small correlation with Web site quality, and Web sites displaying the HONCode badge and commercial sites had lower readability scores. Popular search engines appear to offer generally reliable results pointing to mostly good or better quality mental health Web sites. However, additional work is needed to make these sites more readable.

Analysis of equi-intensity curves and NU distribution of EAS

NASA Technical Reports Server (NTRS)

Tanahashi, G.

1985-01-01

The distribution of the number of muons in extensive air showers (EAS) and the equi-intensity curves of EAS are analyzed on the basis of Monte Carlo simulation of various cosmic ray composition and the interaction models. Problems in the two best combined models are discussed.

European Teachers' Technological Pedagogical Content Knowledge (TPCK) and Educational Use of Web Technologies

ERIC Educational Resources Information Center

Baris, Mehmet Fatih

2015-01-01

Several studies have been conducted on technological, pedagogical content knowledge and web-based education. In this study, the Technological Pedagogical Content Knowledge and Educational Use of Web Technologies (TPCK-W) were analyzed in addition to the self-efficacy and attitudes of 33 teachers from eight different branches carrying out their…

A Study of Multimedia Annotation of Web-Based Materials

ERIC Educational Resources Information Center

Hwang, Wu-Yuin; Wang, Chin-Yu; Sharples, Mike

2007-01-01

Web-based learning has become an important way to enhance learning and teaching, offering many learning opportunities. A limitation of current Web-based learning is the restricted ability of students to personalize and annotate the learning materials. Providing personalized tools and analyzing some types of learning behavior, such as students'…

A Semiotic Analysis of Icons on the World Wide Web.

ERIC Educational Resources Information Center

Ma, Yan

The World Wide Web allows users to interact with a graphic interface to search information in a hypermedia and multimedia environment. Graphics serve as reference points on the World Wide Web for searching and retrieving information. This study analyzed the culturally constructed syntax patterns, or codes, embedded in the icons of library…

Using the World Wide Web as a Teaching Tool: Analyzing Images of Aging and the Visual Needs of an Aging Society.

ERIC Educational Resources Information Center

Jakobi, Patricia

1999-01-01

Analysis of Web site images of aging to identify positive and negative representations can help teach students about social perceptions of older adults. Another learning experience involves consideration of the needs of older adults in Web site design. (SK)

Knowledge Management of Web Financial Reporting in Human-Computer Interactive Perspective

ERIC Educational Resources Information Center

Wang, Dong; Chen, Yujing; Xu, Jing

2017-01-01

Handling and analyzing to web financial data is becoming a challenge issue in knowledge management and education to accounting practitioners. eXtensible Business Reporting Language (XBRL), which is a type of web financial reporting, describes and recognizes financial items by tagging metadata. The goal is to make it possible for financial reports…

A Web platform for the interactive visualization and analysis of the 3D fractal dimension of MRI data.

PubMed

Jiménez, J; López, A M; Cruz, J; Esteban, F J; Navas, J; Villoslada, P; Ruiz de Miras, J

2014-10-01

This study presents a Web platform (http://3dfd.ujaen.es) for computing and analyzing the 3D fractal dimension (3DFD) from volumetric data in an efficient, visual and interactive way. The Web platform is specially designed for working with magnetic resonance images (MRIs) of the brain. The program estimates the 3DFD by calculating the 3D box-counting of the entire volume of the brain, and also of its 3D skeleton. All of this is done in a graphical, fast and optimized way by using novel technologies like CUDA and WebGL. The usefulness of the Web platform presented is demonstrated by its application in a case study where an analysis and characterization of groups of 3D MR images is performed for three neurodegenerative diseases: Multiple Sclerosis, Intrauterine Growth Restriction and Alzheimer's disease. To the best of our knowledge, this is the first Web platform that allows the users to calculate, visualize, analyze and compare the 3DFD from MRI images in the cloud. Copyright © 2014 Elsevier Inc. All rights reserved.

webPIPSA: a web server for the comparison of protein interaction properties

PubMed Central

Richter, Stefan; Wenzel, Anne; Stein, Matthias; Gabdoulline, Razif R.; Wade, Rebecca C.

2008-01-01

Protein molecular interaction fields are key determinants of protein functionality. PIPSA (Protein Interaction Property Similarity Analysis) is a procedure to compare and analyze protein molecular interaction fields, such as the electrostatic potential. PIPSA may assist in protein functional assignment, classification of proteins, the comparison of binding properties and the estimation of enzyme kinetic parameters. webPIPSA is a web server that enables the use of PIPSA to compare and analyze protein electrostatic potentials. While PIPSA can be run with downloadable software (see http://projects.eml.org/mcm/software/pipsa), webPIPSA extends and simplifies a PIPSA run. This allows non-expert users to perform PIPSA for their protein datasets. With input protein coordinates, the superposition of protein structures, as well as the computation and analysis of electrostatic potentials, is automated. The results are provided as electrostatic similarity matrices from an all-pairwise comparison of the proteins which can be subjected to clustering and visualized as epograms (tree-like diagrams showing electrostatic potential differences) or heat maps. webPIPSA is freely available at: http://pipsa.eml.org. PMID:18420653

Cosmic ray knee and new physics at the TeV scale

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

Barceló, Roberto; Masip, Manuel; Mastromatteo, Iacopo, E-mail: rbarcelo@ugr.es, E-mail: masip@ugr.es, E-mail: mastroma@sissa.it

2009-06-01

We analyze the possibility that the cosmic ray knee appears at an energy threshold where the proton-dark matter cross section becomes large due to new TeV physics. It has been shown that such interactions could break the proton and produce a diffuse gamma ray flux consistent with MILAGRO observations. We argue that this hypothesis implies knees that scale with the atomic mass for the different nuclei, as KASKADE data seem to indicate. We find that to explain the change in the spectral index in the flux from E{sup −2.7} to E{sup −3.1} the cross section must grow like E{sup 0.4+β}more » above the knee, where β = 0.3–0.6 parametrizes the energy dependence of the age (τ∝E{sup −β}) of the cosmic rays reaching the Earth. The hypothesis also requires mbarn cross sections (that could be modelled with TeV gravity) and large densities of dark matter (that could be clumped around the sources of cosmic rays). We argue that neutrinos would also exhibit a threshold at E = (m{sub χ}/m{sub p}) E{sub knee} ≈ 10{sup 8} GeV where their interaction with a nucleon becomes strong. Therefore, the observation at ICECUBE or ANITA of standard neutrino events above this threshold would disprove the scenario.« less

Observation of the thunderstorm-related ground cosmic ray flux variations by ARGO-YBJ

NASA Astrophysics Data System (ADS)

Bartoli, B.; Bernardini, P.; Bi, X. J.; Cao, Z.; Catalanotti, S.; Chen, S. Z.; Chen, T. L.; Cui, S. W.; Dai, B. Z.; D'Amone, A.; Danzengluobu; De Mitri, I.; D'Ettorre Piazzoli, B.; Di Girolamo, T.; Di Sciascio, G.; Feng, C. F.; Feng, Zhaoyang; Feng, Zhenyong; Gao, W.; Gou, Q. B.; Guo, Y. Q.; He, H. H.; Hu, Haibing; Hu, Hongbo; Iacovacci, M.; Iuppa, R.; Jia, H. Y.; Labaciren; Li, H. J.; Liu, C.; Liu, J.; Liu, M. Y.; Lu, H.; Ma, L. L.; Ma, X. H.; Mancarella, G.; Mari, S. M.; Marsella, G.; Mastroianni, S.; Montini, P.; Ning, C. C.; Perrone, L.; Pistilli, P.; Salvini, P.; Santonico, R.; Shen, P. R.; Sheng, X. D.; Shi, F.; Surdo, A.; Tan, Y. H.; Vallania, P.; Vernetto, S.; Vigorito, C.; Wang, H.; Wu, C. Y.; Wu, H. R.; Xue, L.; Yang, Q. Y.; Yang, X. C.; Yao, Z. G.; Yuan, A. F.; Zha, M.; Zhang, H. M.; Zhang, L.; Zhang, X. Y.; Zhang, Y.; Zhao, J.; Zhaxiciren; Zhaxisangzhu; Zhou, X. X.; Zhu, F. R.; Zhu, Q. Q.; D'Alessandro, F.; ARGO-YBJ Collaboration

2018-02-01

A correlation between the secondary cosmic ray flux and the near-earth electric field intensity, measured during thunderstorms, has been found by analyzing the data of the ARGO-YBJ experiment, a full coverage air shower array located at the Yangbajing Cosmic Ray Laboratory (4300 m a. s. l., Tibet, China). The counting rates of showers with different particle multiplicities (m =1 , 2, 3, and ≥4 ) have been found to be strongly dependent upon the intensity and polarity of the electric field measured during the course of 15 thunderstorms. In negative electric fields (i.e., accelerating negative charges downwards), the counting rates increase with increasing electric field strength. In positive fields, the rates decrease with field intensity until a certain value of the field EFmin (whose value depends on the event multiplicity), above which the rates begin increasing. By using Monte Carlo simulations, we found that this peculiar behavior can be well described by the presence of an electric field in a layer of thickness of a few hundred meters in the atmosphere above the detector, which accelerates/decelerates the secondary shower particles of opposite charge, modifying the number of particles with energy exceeding the detector threshold. These results, for the first time to our knowledge, give a consistent explanation for the origin of the variation of the electron/positron flux observed for decades by high altitude cosmic ray detectors during thunderstorms.

Interstellar and Planetary Analogs in the Laboratory

NASA Technical Reports Server (NTRS)

Salama, Farid

2013-01-01

We present and discuss the unique capabilities of the laboratory facility, COSmIC, that was developed at NASA Ames to investigate the interaction of ionizing radiation (UV, charged particles) with molecular species (neutral molecules, radicals and ions) and carbonaceous grains in the Solar System and in the Interstellar Medium (ISM). COSmIC stands for Cosmic Simulation Chamber, a laboratory chamber where interstellar and planetary analogs are generated, processed and analyzed. It is composed of a pulsed discharge nozzle (PDN) expansion that generates a free jet supersonic expansion in a plasma cavity coupled to two ultrahigh-sensitivity, complementary in situ diagnostics: a cavity ring down spectroscopy (CRDS) system for photonic detection and a Reflectron time-of-flight mass spectrometer (ReTOF-MS) for mass detection. This setup allows the study of molecules, ions and solids under the low temperature and high vacuum conditions that are required to simulate some interstellar, circumstellar and planetary physical environments providing new fundamental insights on the molecular level into the processes that are critical to the chemistry in the ISM, circumstellar and planet forming regions, and on icy objects in the Solar System. Recent laboratory results that were obtained using COSmIC will be discussed, in particular the progress that have been achieved in monitoring in the laboratory the formation of solid particles from their gas-phase molecular precursors in environments as varied as circumstellar outflow and planetary atmospheres.

The persistent cosmic web and its filamentary structure - I. Theory and implementation

NASA Astrophysics Data System (ADS)

Sousbie, T.

2011-06-01

We present DisPerSE, a novel approach to the coherent multiscale identification of all types of astrophysical structures, in particular the filaments, in the large-scale distribution of the matter in the Universe. This method and the corresponding piece of software allows for a genuinely scale-free and parameter-free identification of the voids, walls, filaments, clusters and their configuration within the cosmic web, directly from the discrete distribution of particles in N-body simulations or galaxies in sparse observational catalogues. To achieve that goal, the method works directly over the Delaunay tessellation of the discrete sample and uses the Delaunay tessellation field estimator density computed at each tracer particle; no further sampling, smoothing or processing of the density field is required. The idea is based on recent advances in distinct subdomains of the computational topology, namely the discrete Morse theory which allows for a rigorous application of topological principles to astrophysical data sets, and the theory of persistence, which allows us to consistently account for the intrinsic uncertainty and Poisson noise within data sets. Practically, the user can define a given persistence level in terms of robustness with respect to noise (defined as a 'number of σ') and the algorithm returns the structures with the corresponding significance as sets of critical points, lines, surfaces and volumes corresponding to the clusters, filaments, walls and voids - filaments, connected at cluster nodes, crawling along the edges of walls bounding the voids. From a geometrical point of view, the method is also interesting as it allows for a robust quantification of the topological properties of a discrete distribution in terms of Betti numbers or Euler characteristics, without having to resort to smoothing or having to define a particular scale. In this paper, we introduce the necessary mathematical background and describe the method and implementation, while we address the application to 3D simulated and observed data sets in the companion paper (Sousbie, Pichon & Kawahara, Paper II).

Sloan Great Wall as a complex of superclusters with collapsing cores

NASA Astrophysics Data System (ADS)

Einasto, Maret; Lietzen, Heidi; Gramann, Mirt; Tempel, Elmo; Saar, Enn; Liivamägi, Lauri Juhan; Heinämäki, Pekka; Nurmi, Pasi; Einasto, Jaan

2016-10-01

Context. The formation and evolution of the cosmic web is governed by the gravitational attraction of dark matter and antigravity of dark energy (cosmological constant). In the cosmic web, galaxy superclusters or their high-density cores are the largest objects that may collapse at present or during the future evolution. Aims: We study the dynamical state and possible future evolution of galaxy superclusters from the Sloan Great Wall (SGW), the richest galaxy system in the nearby Universe. Methods: We calculated supercluster masses using dynamical masses of galaxy groups and stellar masses of galaxies. We employed normal mixture modelling to study the structure of rich SGW superclusters and search for components (cores) in superclusters. We analysed the radial mass distribution in the high-density cores of superclusters centred approximately at rich clusters and used the spherical collapse model to study their dynamical state. Results: The lower limit of the total mass of the SGW is approximately M = 2.5 × 1016 h-1 M⊙. Different mass estimators of superclusters agree well, the main uncertainties in masses of superclusters come from missing groups and clusters. We detected three high-density cores in the richest SGW supercluster (SCl 027) and two in the second richest supercluster (SCl 019). They have masses of 1.2 - 5.9 × 1015 h-1 M⊙ and sizes of up to ≈60 h-1 Mpc. The high-density cores of superclusters are very elongated, flattened perpendicularly to the line of sight. The comparison of the radial mass distribution in the high-density cores with the predictions of spherical collapse model suggests that their central regions with radii smaller than 8 h-1 Mpc and masses of up to M = 2 × 1015 h-1 M⊙ may be collapsing. Conclusions: The rich SGW superclusters with their high-density cores represent dynamically evolving environments for studies of the properties of galaxies and galaxy systems.

The RESOLVE Survey Atomic Gas Census and Environmental Influences on Galaxy Gas Reservoirs

NASA Astrophysics Data System (ADS)

Stark, David V.; Kannappan, Sheila J.; Eckert, Kathleen D.; Florez, Jonathan; Hall, Kirsten R.; Watson, Linda C.; Hoversten, Erik A.; Burchett, Joseph N.; Guynn, David T.; Baker, Ashley D.; Moffett, Amanda J.; Berlind, Andreas A.; Norris, Mark A.; Haynes, Martha P.; Giovanelli, Riccardo; Leroy, Adam K.; Pisano, D. J.; Wei, Lisa H.; Gonzalez, Roberto E.; Calderon, Victor F.

2016-12-01

We present the H I mass inventory for the REsolved Spectroscopy Of a Local VolumE (RESOLVE) survey, a volume-limited, multi-wavelength census of >1500 z = 0 galaxies spanning diverse environments and complete in baryonic mass down to dwarfs of ∼109 {M}ȯ . This first 21 cm data release provides robust detections or strong upper limits (1.4M H I < 5%–10% of stellar mass M *) for ∼94% of RESOLVE. We examine global atomic gas-to-stellar mass ratios (G/S) in relation to galaxy environment using several metrics: group dark matter halo mass M h, central/satellite designation, relative mass density of the cosmic web, and distance to the nearest massive group. We find that at fixed M *, satellites have decreasing G/S with increasing M h starting clearly at M h ∼ 1012 {M}ȯ , suggesting the presence of starvation and/or stripping mechanisms associated with halo gas heating in intermediate-mass groups. The analogous relationship for centrals is uncertain because halo abundance matching builds in relationships between central G/S, stellar mass, and halo mass, which depend on the integrated group property used as a proxy for halo mass (stellar or baryonic mass). On larger scales G/S trends are less sensitive to the abundance matching method. At fixed M h ≤ 1012 {M}ȯ , the fraction of gas-poor centrals increases with large-scale structure density. In overdense regions, we identify a rare population of gas-poor centrals in low-mass (M h < 1011.4 {M}ȯ ) halos primarily located within ∼1.5× the virial radius of more massive (M h > 1012 {M}ȯ ) halos, suggesting that gas stripping and/or starvation may be induced by interactions with larger halos or the surrounding cosmic web. We find that the detailed relationship between G/S and environment varies when we examine different subvolumes of RESOLVE independently, which we suggest may be a signature of assembly bias.

How Teachers Use and Manage Their Blogs? A Cluster Analysis of Teachers' Blogs in Taiwan

ERIC Educational Resources Information Center

Liu, Eric Zhi-Feng; Hou, Huei-Tse

2013-01-01

The development of Web 2.0 has ushered in a new set of web-based tools, including blogs. This study focused on how teachers use and manage their blogs. A sample of 165 teachers' blogs in Taiwan was analyzed by factor analysis, cluster analysis and qualitative content analysis. First, the teachers' blogs were analyzed according to six criteria…

The stationary non-equilibrium plasma of cosmic-ray electrons and positrons

NASA Astrophysics Data System (ADS)

Tomaschitz, Roman

2016-06-01

The statistical properties of the two-component plasma of cosmic-ray electrons and positrons measured by the AMS-02 experiment on the International Space Station and the HESS array of imaging atmospheric Cherenkov telescopes are analyzed. Stationary non-equilibrium distributions defining the relativistic electron-positron plasma are derived semi-empirically by performing spectral fits to the flux data and reconstructing the spectral number densities of the electronic and positronic components in phase space. These distributions are relativistic power-law densities with exponential cutoff, admitting an extensive entropy variable and converging to the Maxwell-Boltzmann or Fermi-Dirac distributions in the non-relativistic limit. Cosmic-ray electrons and positrons constitute a classical (low-density high-temperature) plasma due to the low fugacity in the quantized partition function. The positron fraction is assembled from the flux densities inferred from least-squares fits to the electron and positron spectra and is subjected to test by comparing with the AMS-02 flux ratio measured in the GeV interval. The calculated positron fraction extends to TeV energies, predicting a broad spectral peak at about 1 TeV followed by exponential decay.

A balloon measurement of the isotopic composition of galactic cosmic ray boron, carbon and nitrogen. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Zumberge, J. F.

1981-01-01

The isotopic compositions of galactic cosmic ray boron, carbon, and nitrogen were measured at energies near 300 MeV amu, using a balloon-borne instrument at an atmospheric depth of approximately 5 g/sq cm. The calibrations of the detectors comprising the instrument are described. The saturation properties of the cesium iodide scintillators used for measurement of particle energy are studied in the context of analyzing the data for mass. The achieved rms mass resolution varies from approximately 0.3 amu at boron to approximately 0.5 amu at nitrogen, consistent with a theoretical analysis of the contributing factors. Corrected for detector interactions and the effects of the residual atmosphere the results are B-10/B=0.33 (+0.17, -0.11), C-13/C=0.06 (+0.13, -0.11), and N-15/N=0.42 (+0.19, -0.17). A model of galactic propagation and solar modulation is described. Assuming a cosmic ray source composition of solar-like isotopic abundances, the model predicts abundances near Earth consistent with the measurements.

Swift heavy ion irradiation of interstellar dust analogues. Small carbonaceous species released by cosmic rays

NASA Astrophysics Data System (ADS)

Dartois, E.; Chabot, M.; Pino, T.; Béroff, K.; Godard, M.; Severin, D.; Bender, M.; Trautmann, C.

2017-03-01

Context. Interstellar dust grain particles are immersed in vacuum ultraviolet (VUV) and cosmic ray radiation environments influencing their physicochemical composition. Owing to the energetic ionizing interactions, carbonaceous dust particles release fragments that have direct impact on the gas phase chemistry. Aims: The exposure of carbonaceous dust analogues to cosmic rays is simulated in the laboratory by irradiating films of hydrogenated amorphous carbon interstellar analogues with energetic ions. New species formed and released into the gas phase are explored. Methods: Thin carbonaceous interstellar dust analogues were irradiated with gold (950 MeV), xenon (630 MeV), and carbon (43 MeV) ions at the GSI UNILAC accelerator. The evolution of the dust analogues is monitored in situ as a function of fluence at 40, 100, and 300 K. Effects on the solid phase are studied by means of infrared spectroscopy complemented by simultaneously recording mass spectrometry of species released into the gas phase. Results: Specific species produced and released under the ion beam are analyzed. Cross sections derived from ion-solid interaction processes are implemented in an astrophysical context.

Web Analytics

EPA Pesticide Factsheets

EPA’s Web Analytics Program collects, analyzes, and provides reports on traffic, quality assurance, and customer satisfaction metrics for EPA’s website. The program uses a variety of analytics tools, including Google Analytics and CrazyEgg.

A Comparative Study of the Relationship between Social Dimension of Web 2.0 Technologies and E-Learning: Students' View in Germany and Taiwan

ERIC Educational Resources Information Center

Ahrens, Andreas; Wen, Melody Ling-Yu; Huang, Ya-Hui; Zascerinska, Jelena; Bassus, Olaf

2010-01-01

The social dimension of Web 2.0 penetrates our society more thoroughly with the availability of broadband services. Aim of the following paper is to analyze the students' view on the relationship between social dimension of Web 2.0 technologies and e-learning within education. The meaning of the key concept of social dimension of Web 2.0 is…

The Web as an Information Resource in K-12 Education: Strategies for Supporting Students in Searching and Processing Information

ERIC Educational Resources Information Center

Kuiper, Els; Volman, Monique; Terwel, Jan

2005-01-01

The use of the Web in K-12 education has increased substantially in recent years. The Web, however, does not support the learning processes of students as a matter of course. In this review, the authors analyze what research says about the demands that the use of the Web as an information resource in education makes on the support and supervision…

Remote sensing of tropospheric turbulence using GPS radio occultation

NASA Astrophysics Data System (ADS)

Shume, Esayas; Ao, Chi

2016-07-01

Radio occultation (RO) measurements are sensitive to the small-scale irregularities in the atmosphere. In this study, we present a new technique to estimate tropospheric turbulence strength (namely, scintillation index) by analyzing RO amplitude fluctuations in impact parameter domain. GPS RO observations from the COSMIC (Constellation Observing System for Meteorology, Ionosphere, and Climate) satellites enabled us to calculate global maps of scintillation measures, revealing the seasonal, latitudinal, and longitudinal characteristics of the turbulent troposphere. Such information are both difficult and expensive to obtain especially over the oceans. To verify our approach, simulation experiments using the multiple phase screen (MPS) method were conducted. The results show that scintillation indices inferred from the MPS simulations are in good agreement with scintillation measures estimated from COSMIC observations.

Radio Astronomy Explorer (RAE) 1 observations of terrestrial radio noise

NASA Technical Reports Server (NTRS)

Herman, J. R.; Caruso, J. A.

1971-01-01

Radio Astonomy Explorer (RAE) 1 data are analyzed to establish characteristics of HF terrestrial radio noise at an altitude of about 6000 km. Time and frequency variations in amplitude of the observed noise well above cosmic noise background are explained on the basis of temporal and spatial variations in ionospheric critical frequency coupled with those in noise source distributions. It is shown that terrestrial noise regularly breaks through the ionosphere and reaches RAE with magnitudes 15 or more db higher than cosmic noise background. Maximum terrestrial noise is observed when RAE is over the dark side of the Earth in the neighborhood of equatorial continental land masses where thunderstorms occur most frequently. The observed noise level is 30-40 db lower with RAE over oceans.

ON TEMPORAL VARIATIONS OF THE MULTI-TeV COSMIC RAY ANISOTROPY USING THE TIBET III AIR SHOWER ARRAY

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

Amenomori, M.; Bi, X. J.; Ding, L. K.

2010-03-01

We analyze the large-scale two-dimensional sidereal anisotropy of multi-TeV cosmic rays (CRs) by the Tibet Air Shower Array, with the data taken from 1999 November to 2008 December. To explore temporal variations of the anisotropy, the data set is divided into nine intervals, each with a time span of about one year. The sidereal anisotropy of magnitude, about 0.1%, appears fairly stable from year to year over the entire observation period of nine years. This indicates that the anisotropy of TeV Galactic CRs remains insensitive to solar activities since the observation period covers more than half of the 23rd solarmore » cycle.« less

The Voyager Cosmic Ray Experiment

NASA Technical Reports Server (NTRS)

Stilwell, D. E.; Davis, W. D.; Joyce, R. M.; Mcdonald, F. B.; Trainor, J. H.; Althouse, W. E.; Cummings, A. C.; Garrard, T. L.; Stone, E. C.; Vogt, R. E.

1979-01-01

The Voyager Cosmic Ray Experiment includes seven dE/dx-E telescopes to measure the energy and charge of particles with atomic numbers from 1 to 26 in the energy range 1-500 MeV/nucleon and to measure electron energy in the range from 3 to 110 MeV. Isotopic composition of hydrogen through sulfur in the range up to 75 Mev/nucleon can also be resolved. The electronic systems include a dual-gain, charge sensitive preamplifier, 4096-channel pulse height analyzers for three parameter analysis of selected events, and an event type readout polling scheme to maximize the use of available telemetry space and to enhance the occurrence of rare events in the data. Details of the detector, electronic and mechanical design are presented.

Chemical characterization of seven Large Area Collector particles by SXRF. [cosmic dust composition

NASA Technical Reports Server (NTRS)

Flynn, G. J.; Sutton, S. R.

1991-01-01

Optical microscopy and synchrotron X-ray fluorescence (SXRF) are used to analyze the chemical composition of seven dark-appearing cosmic-dust particles obtained in the stratosphere during NASA Johnson Large Area Collector flights. The experimental setup and procedures are outlined, and the results are presented in extensive tables. Three of the particles had abundances similar to those of chondrites (except for low Ca values in one particle); two had a metallic appearance and spectra dominated by Fe and Zn; one contained Cu and Cr plus small amounts of Fe and Zn; and one had igneous-type abundances of minor and trace elements while containing all of the elements seen in chondritic particles, suggesting it may be of extraterrestrial origin.

Ion implantation effects in 'cosmic' dust grains

NASA Technical Reports Server (NTRS)

Bibring, J. P.; Langevin, Y.; Maurette, M.; Meunier, R.; Jouffrey, B.; Jouret, C.

1974-01-01

Cosmic dust grains, whatever their origin may be, have probably suffered a complex sequence of events including exposure to high doses of low-energy nuclear particles and cycles of turbulent motions. High-voltage electron microscope observations of micron-sized grains either naturally exposed to space environmental parameters on the lunar surface or artificially subjected to space simulated conditions strongly suggest that such events could drastically modify the mineralogical composition of the grains and considerably ease their aggregation during collisions at low speeds. Furthermore, combined mass spectrometer and ionic analyzer studies show that small carbon compounds can be both synthesized during the implantation of a mixture of low-energy D, C, N ions in various solids and released in space by ion sputtering.

Gas Accretion and Star Formation Rates

NASA Astrophysics Data System (ADS)

Sánchez Almeida, Jorge

Cosmological numerical simulations of galaxy evolution show that accretion of metal-poor gas from the cosmic web drives the star formation in galaxy disks. Unfortunately, the observational support for this theoretical prediction is still indirect, and modeling and analysis are required to identify hints as actual signs of star formation feeding from metal-poor gas accretion. Thus, a meticulous interpretation of the observations is crucial, and this observational review begins with a simple theoretical description of the physical process and the key ingredients it involves, including the properties of the accreted gas and of the star formation that it induces. A number of observations pointing out the connection between metal-poor gas accretion and star formation are analyzed, specifically, the short gas-consumption time-scale compared to the age of the stellar populations, the fundamental metallicity relationship, the relationship between disk morphology and gas metallicity, the existence of metallicity drops in starbursts of star-forming galaxies, the so-called G dwarf problem, the existence of a minimum metallicity for the star-forming gas in the local universe, the origin of the α-enhanced gas forming stars in the local universe, the metallicity of the quiescent BCDs, and the direct measurements of gas accretion onto galaxies. A final section discusses intrinsic difficulties to obtain direct observational evidence, and points out alternative observational pathways to further consolidate the current ideas.

A hot X-ray filament associated with A3017 galaxy cluster

NASA Astrophysics Data System (ADS)

Parekh, V.; Durret, F.; Padmanabh, P.; Pandge, M. B.

2017-09-01

Recent simulations and observations have shown large-scale filaments in the cosmic web connecting nodes, with accreting materials (baryonic and dark matter) flowing through them. Current high-sensitivity observations also show that the propagation of shocks through filaments can heat them up and make filaments visible between two or more galaxy clusters or around massive clusters, based on optical and/or X-ray observations. We are reporting here the special case of the cluster A3017 associated with a hot filament. The temperature of the filament is 3.4^{-0.77}_{+1.30} keV and its length is ∼1 Mpc. We have analysed its archival Chandra data and report various properties. We also analysed GMRT 235/610 MHz radio data. Radio observations have revealed symmetric two-sided lobes that fill cavities in the A3017 cluster core region, associated with central active galactic nucleus. In the radio map, we also noticed a peculiar linear vertical radio structure in the X-ray filament region which might be associated with a cosmic filament shock. This radio structure could be a radio phoenix or old plasma where an old relativistic population is re-accelerated by shock propagation. Finally, we put an upper limit on the radio luminosity of the filament region.

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

Naidoo, Krishna; Benoit-Levy, Aurelien; Lahav, Ofer

Understanding the observed Cold Spot (CS) (temperature of ~ -150 mu K at its centre) on the Cosmic Microwave Background (CMB) is an outstanding problem. Explanations vary from assuming it is just a ≳ 3σ primordial Gaussian fluctuation to the imprint of a supervoid via the Integrated Sachs-Wolfe and Rees-Sciama (ISW+RS) effects. Since single spherical supervoids cannot account for the full profile, the ISW+RS of multiple line-of-sight voids is studied here to mimic the structure of the cosmic web. Two structure configurations are considered. The first, through simulations of 20 voids, produces a central mean temperature of ~-50 mu K.more » In this model the central CS temperature lies at ~ 2σ but fails to explain the CS hot ring. An alternative multi-void model (using more pronounced compensated voids) produces much smaller temperature profiles, but contains a prominent hot ring. Arrangements containing closely placed voids at low redshift are found to be particularly well suited to produce CS-like profiles. We then measure the significance of the CS if CS-like profiles (which are fitted to the ISW+RS of multi-void scenarios) are removed. Furthermore, the CS tension with the LCDM model can be reduced dramatically for an array of temperature profiles smaller than the CS itself.« less

Speaking the Same Language: Information College Seekers Look for on a College Web Site

ERIC Educational Resources Information Center

Tucciarone, Krista M.

2009-01-01

The purpose of this qualitative study is to analyze and understand what information students seek from a college's Web site during their college search. Often, college Web sites fail either to offer students an interactive dialogue or to involve them in the communicative process, negatively affecting students' college search. Undergraduate…

Science on the Web: Secondary School Students' Navigation Patterns and Preferred Pages' Characteristics

ERIC Educational Resources Information Center

Dimopoulos, Kostas; Asimakopoulos, Apostolos

2010-01-01

This study aims to explore navigation patterns and preferred pages' characteristics of ten secondary school students searching the web for information about cloning. The students navigated the Web for as long as they wished in a context of minimum support of teaching staff. Their navigation patterns were analyzed using audit trail data software.…

Web Log Analysis: A Study of Instructor Evaluations Done Online

ERIC Educational Resources Information Center

Klassen, Kenneth J.; Smith, Wayne

2004-01-01

This paper focuses on developing a relatively simple method for analyzing web-logs. It also explores the challenges and benefits of web-log analysis. The study of student behavior on this site provides insights into website design and the effectiveness of this site in particular. Another benefit realized from the paper is the ease with which these…

Users' Perceptions of the Web As Revealed by Transaction Log Analysis.

ERIC Educational Resources Information Center

Moukdad, Haidar; Large, Andrew

2001-01-01

Describes the results of a transaction log analysis of a Web search engine, WebCrawler, to analyze user's queries for information retrieval. Results suggest most users do not employ advanced search features, and the linguistic structure often resembles a human-human communication model that is not always successful in human-computer communication.…

Web-Based Learning Programs: Use by Learners with Various Cognitive Styles

ERIC Educational Resources Information Center

Chen, Ling-Hsiu

2010-01-01

To consider how Web-based learning program is utilized by learners with different cognitive styles, this study presents a Web-based learning system (WBLS) and analyzes learners' browsing data recorded in the log file to identify how learners' cognitive styles and learning behavior are related. In order to develop an adapted WBLS, this study also…

A Web 2.0 Interface to Ion Stopping Power and Other Physics Routines for High Energy Density Physics Applications

NASA Astrophysics Data System (ADS)

Stoltz, Peter; Veitzer, Seth

2008-04-01

We present a new Web 2.0-based interface to physics routines for High Energy Density Physics applications. These routines include models for ion stopping power, sputtering, secondary electron yields and energies, impact ionization cross sections, and atomic radiated power. The Web 2.0 interface allows users to easily explore the results of the models before using the routines within other codes or to analyze experimental results. We discuss how we used various Web 2.0 tools, including the Python 2.5, Django, and the Yahoo User Interface library. Finally, we demonstrate the interface by showing as an example the stopping power algorithms researchers are currently using within the Hydra code to analyze warm, dense matter experiments underway at the Neutralized Drift Compression Experiment facility at Lawrence Berkeley National Laboratory.

Cosmic Rays: "A Thin Rain of Charged Particles."

ERIC Educational Resources Information Center

Friedlander, Michael

1990-01-01

Discussed are balloons and electroscopes, understanding cosmic rays, cosmic ray paths, isotopes and cosmic-ray travel, sources of cosmic rays, and accelerating cosmic rays. Some of the history of the discovery and study of cosmic rays is presented. (CW)

Study on online community user motif using web usage mining

NASA Astrophysics Data System (ADS)

Alphy, Meera; Sharma, Ajay

2016-04-01

The Web usage mining is the application of data mining, which is used to extract useful information from the online community. The World Wide Web contains at least 4.73 billion pages according to Indexed Web and it contains at least 228.52 million pages according Dutch Indexed web on 6th august 2015, Thursday. It’s difficult to get needed data from these billions of web pages in World Wide Web. Here is the importance of web usage mining. Personalizing the search engine helps the web user to identify the most used data in an easy way. It reduces the time consumption; automatic site search and automatic restore the useful sites. This study represents the old techniques to latest techniques used in pattern discovery and analysis in web usage mining from 1996 to 2015. Analyzing user motif helps in the improvement of business, e-commerce, personalisation and improvement of websites.

Communicable Disease Research

NASA Technical Reports Server (NTRS)

1982-01-01

The COSMIC program FITLOS is used regularly by the Centers for Disease Control (CDC), for analyzing data from radioimmunoassays, which involve testing human body substances to provide information on how deficits or excesses of those substances affect a body's ability to ward off disease. A liquid scintillation counter's data is analyzed by the FITLOS program. FITLOS data, then aids in establishing reference methods for hospitals and other health laboratories in their radioimmunoassays. CDC's use of this program enabled them to avoid the cost of designing and developing a new program.

Development of a data reduction expert assistant

NASA Technical Reports Server (NTRS)

Miller, Glenn E.

1994-01-01

This report documents the development and deployment of the Data Reduction Expert Assistant (DRACO). The system was successfully applied to two astronomical research projects. The first was the removal of cosmic ray artifacts from Hubble Space Telescope (HST) Wide Field Planetary Camera data. The second was the reduction and calibration of low-dispersion CCD spectra taken from a ground-based telescope. This has validated our basic approach and demonstrated the applicability of this technology. This work has been made available to the scientific community in two ways. First, we have published the work in the scientific literature and presented papers at relevant conferences. Secondly, we have made the entire system (including documentation and source code) available to the community via the World Wide Web.

Antimatter in the universe

NASA Technical Reports Server (NTRS)

Stigman, G.

1973-01-01

The means of detecting the presence of antimatter in the universe are discussed. Both direct, annihilation processes, and indirect, cosmic ray particles, were analyzed. All results were negative and it was concluded that no antimatter exists, if the universe is in fact symmetric. If the universe is not symmetric then matter and antimatter are well separated from each other.

Web site development: applying aesthetics to promote breast health education and awareness.

PubMed

Thomas, Barbara; Goldsmith, Susan B; Forrest, Anne; Marshall, Renée

2002-01-01

This article describes the process of establishing a Web site as part of a collaborative project using visual art to promote breast health education. The need for a more "user-friendly" comprehensive breast health Web site that is aesthetically rewarding was identified after an analysis of current Web sites available through the World Wide Web. Two predetermined sets of criteria, accountability and aesthetics, were used to analyze these sites and to generate ideas for creating a breast health education Web site using visual art. Results of the analyses conducted are included as well as the factors to consider for incorporating into a Web site. The process specified is thorough and can be applied to establish a Web site that is aesthetically rewarding and informative for a variety of educational purposes.

Readability and comprehensibility of patient education material in hand-related web sites.

PubMed

Wang, Steve W; Capo, John T; Orillaza, Nathaniel

2009-09-01

As patients are more frequently referring to the Internet for information on their musculoskeletal problems, the readability and comprehensibility of these educational materials becomes increasingly more important to most of the lay public. In this study, we investigated the readability of the currently available web sites of the American Society for Surgery of the Hand (ASSH) and the American Academy of Orthopaedic Surgeons (AAOS) that pertain to hand and wrist problems, to assess their usefulness as a source for patient information. We analyzed all articles available in 2008 from the AAOS web site within the Patient Education Library under the heading, "Hand & Wrist" and from the ASSH web site under the heading, "Hand Conditions." A total of 83 articles were identified for hand conditions. Each article was analyzed by the Flesch-Kincaid program available in Microsoft Office Word software and the Dale-Chall grade-level assessor. These program models analyze all words in the specified text and return a grade level that corresponds to the difficulty level of the text. The AAOS web sites contained 34 articles with a mean Flesch-Kincaid grade level of 8.5 and a mean Dale-Chall grade level of 8.8. The ASSH web site contained 49 articles showing a mean Flesch-Kincaid grade level of 10.4 and a mean Dale-Chall grade level of 10.8. Our results suggest that the patient education materials found on the AAOS and ASSH web sites have readability scores that are higher than the recommended reading levels and thus may be too difficult to be understood by a substantial portion of the U.S. population.

Evaluation of a metal shear web selectively reinforced with filamentary composites for space shuttle application

NASA Technical Reports Server (NTRS)

Laakso, J. H.; Straayer, J. W.

1974-01-01

A final program summary is reported for test and evaluation activities that were conducted for space shuttle web selection. Large scale advanced composite shear web components were tested and analyzed to evaluate application of advanced composite shear web construction to a space shuttle orbiter thrust structure. The shear web design concept consisted of a titanium-clad + or - 45 deg boron/epoxy web laminate stiffened with vertical boron-epoxy reinforced aluminum stiffeners and logitudinal aluminum stiffening. The design concept was evaluated to be efficient and practical for the application that was studied. Because of the effects of buckling deflections, a requirement is identified for shear buckling resistant design to maximize the efficiency of highly-loaded advanced composite shear webs.

ConfChem Conference on Select 2016 BCCE Presentations: Tracking Student Use of Web-Based Resources for Chemical Education

ERIC Educational Resources Information Center

Bodily, Robert; Wood, Steven

2017-01-01

This paper presents the technical infrastructure required to track student use of web-based resources in an introductory chemistry course, the design of a student dashboard, and the results from analyzing student web-based resource use. Students were tracked as they interacted with online homework problems and high quality course content videos.…

Assessment of Web-Based Authentication Methods in the U.S.: Comparing E-Learning Systems to Internet Healthcare Information Systems

ERIC Educational Resources Information Center

Mattord, Herbert J.

2012-01-01

Organizations continue to rely on password-based authentication methods to control access to many Web-based systems. This research study developed a benchmarking instrument intended to assess authentication methods used in Web-based information systems (IS). It developed an Authentication Method System Index (AMSI) to analyze collected data from…

Student Characteristics, Sense of Community, and Cognitive Achievement in Web-Based and Lab-Based Learning Environments

ERIC Educational Resources Information Center

Overbaugh, Richard C.; Lin, ShinYi

2006-01-01

This study investigated differential effects of learning styles and learning orientation on sense of community and cognitive achievement in Web-based and lab-based university course formats. Students in the Web-based sections achieved higher scores at the "remember" and "understand" levels, but not at the "apply" or "analyze" levels. In terms of…

Web Apollo: a web-based genomic annotation editing platform.

PubMed

Lee, Eduardo; Helt, Gregg A; Reese, Justin T; Munoz-Torres, Monica C; Childers, Chris P; Buels, Robert M; Stein, Lincoln; Holmes, Ian H; Elsik, Christine G; Lewis, Suzanna E

2013-08-30

Web Apollo is the first instantaneous, collaborative genomic annotation editor available on the web. One of the natural consequences following from current advances in sequencing technology is that there are more and more researchers sequencing new genomes. These researchers require tools to describe the functional features of their newly sequenced genomes. With Web Apollo researchers can use any of the common browsers (for example, Chrome or Firefox) to jointly analyze and precisely describe the features of a genome in real time, whether they are in the same room or working from opposite sides of the world.

Web Apollo: a web-based genomic annotation editing platform

PubMed Central

2013-01-01

Web Apollo is the first instantaneous, collaborative genomic annotation editor available on the web. One of the natural consequences following from current advances in sequencing technology is that there are more and more researchers sequencing new genomes. These researchers require tools to describe the functional features of their newly sequenced genomes. With Web Apollo researchers can use any of the common browsers (for example, Chrome or Firefox) to jointly analyze and precisely describe the features of a genome in real time, whether they are in the same room or working from opposite sides of the world. PMID:24000942

The Case of Web-Based Course on Taxation: Current Status, Problems and Future Improvement

NASA Astrophysics Data System (ADS)

Qin, Zhigang

This paper mainly introduces the case of the web-based course on taxation developed by Xiamen University. We analyze the current status, problems and future improvement of the web-based course. The web-based course has the basic contents and modules, but it has several problems including unclear object, lacking interaction, lacking examination module, lacking study management module, and the learning materials and the navigation are too simple. According to its problems, we put forward the measures to improve it.

Archetype-based conversion of EHR content models: pilot experience with a regional EHR system

PubMed Central

2009-01-01

Background Exchange of Electronic Health Record (EHR) data between systems from different suppliers is a major challenge. EHR communication based on archetype methodology has been developed by openEHR and CEN/ISO. The experience of using archetypes in deployed EHR systems is quite limited today. Currently deployed EHR systems with large user bases have their own proprietary way of representing clinical content using various models. This study was designed to investigate the feasibility of representing EHR content models from a regional EHR system as openEHR archetypes and inversely to convert archetypes to the proprietary format. Methods The openEHR EHR Reference Model (RM) and Archetype Model (AM) specifications were used. The template model of the Cambio COSMIC, a regional EHR product from Sweden, was analyzed and compared to the openEHR RM and AM. This study was focused on the convertibility of the EHR semantic models. A semantic mapping between the openEHR RM/AM and the COSMIC template model was produced and used as the basis for developing prototype software that performs automated bi-directional conversion between openEHR archetypes and COSMIC templates. Results Automated bi-directional conversion between openEHR archetype format and COSMIC template format has been achieved. Several archetypes from the openEHR Clinical Knowledge Repository have been imported into COSMIC, preserving most of the structural and terminology related constraints. COSMIC templates from a large regional installation were successfully converted into the openEHR archetype format. The conversion from the COSMIC templates into archetype format preserves nearly all structural and semantic definitions of the original content models. A strategy of gradually adding archetype support to legacy EHR systems was formulated in order to allow sharing of clinical content models defined using different formats. Conclusion The openEHR RM and AM are expressive enough to represent the existing clinical content models from the template based EHR system tested and legacy content models can automatically be converted to archetype format for sharing of knowledge. With some limitations, internationally available archetypes could be converted to the legacy EHR models. Archetype support can be added to legacy EHR systems in an incremental way allowing a migration path to interoperability based on standards. PMID:19570196

Web N.0, the New Development Trend of Internet

NASA Astrophysics Data System (ADS)

Sun, Zhiguo; Wang, Wensheng

This article analyzes the Internet basic theory, the network foundation environment and the user behavior change and so on, Which analyzes the development tendency of existing partial Internet products in the future Internet environment. The article also hot on the concept of cloud computing, Demonstrates the relation between Cloud Computing and Web 2.0 from the angle of Cloud-based end-user applications, The possibly killing application in the future was discussed.

Demographic-Based Content Analysis of Web-Based Health-Related Social Media

PubMed Central

Shahbazi, Moloud; Wiley, Matthew T; Hristidis, Vagelis

2016-01-01

Background An increasing number of patients from diverse demographic groups share and search for health-related information on Web-based social media. However, little is known about the content of the posted information with respect to the users’ demographics. Objective The aims of this study were to analyze the content of Web-based health-related social media based on users’ demographics to identify which health topics are discussed in which social media by which demographic groups and to help guide educational and research activities. Methods We analyze 3 different types of health-related social media: (1) general Web-based social networks Twitter and Google+; (2) drug review websites; and (3) health Web forums, with a total of about 6 million users and 20 million posts. We analyzed the content of these posts based on the demographic group of their authors, in terms of sentiment and emotion, top distinctive terms, and top medical concepts. Results The results of this study are: (1) Pregnancy is the dominant topic for female users in drug review websites and health Web forums, whereas for male users, it is cardiac problems, HIV, and back pain, but this is not the case for Twitter; (2) younger users (0-17 years) mainly talk about attention-deficit hyperactivity disorder (ADHD) and depression-related drugs, users aged 35-44 years discuss about multiple sclerosis (MS) drugs, and middle-aged users (45-64 years) talk about alcohol and smoking; (3) users from the Northeast United States talk about physical disorders, whereas users from the West United States talk about mental disorders and addictive behaviors; (4) Users with higher writing level express less anger in their posts. Conclusion We studied the popular topics and the sentiment based on users' demographics in Web-based health-related social media. Our results provide valuable information, which can help create targeted and effective educational campaigns and guide experts to reach the right users on Web-based social chatter. PMID:27296242

Demographic-Based Content Analysis of Web-Based Health-Related Social Media.

PubMed

Sadah, Shouq A; Shahbazi, Moloud; Wiley, Matthew T; Hristidis, Vagelis

2016-06-13

An increasing number of patients from diverse demographic groups share and search for health-related information on Web-based social media. However, little is known about the content of the posted information with respect to the users' demographics. The aims of this study were to analyze the content of Web-based health-related social media based on users' demographics to identify which health topics are discussed in which social media by which demographic groups and to help guide educational and research activities. We analyze 3 different types of health-related social media: (1) general Web-based social networks Twitter and Google+; (2) drug review websites; and (3) health Web forums, with a total of about 6 million users and 20 million posts. We analyzed the content of these posts based on the demographic group of their authors, in terms of sentiment and emotion, top distinctive terms, and top medical concepts. The results of this study are: (1) Pregnancy is the dominant topic for female users in drug review websites and health Web forums, whereas for male users, it is cardiac problems, HIV, and back pain, but this is not the case for Twitter; (2) younger users (0-17 years) mainly talk about attention-deficit hyperactivity disorder (ADHD) and depression-related drugs, users aged 35-44 years discuss about multiple sclerosis (MS) drugs, and middle-aged users (45-64 years) talk about alcohol and smoking; (3) users from the Northeast United States talk about physical disorders, whereas users from the West United States talk about mental disorders and addictive behaviors; (4) Users with higher writing level express less anger in their posts. We studied the popular topics and the sentiment based on users' demographics in Web-based health-related social media. Our results provide valuable information, which can help create targeted and effective educational campaigns and guide experts to reach the right users on Web-based social chatter.

The Silicon Matrix as a Charge Detector in the ATIC Experiment

NASA Technical Reports Server (NTRS)

Zatsepin, V. I.; Adams, J. H.; Ahn, H. S.; Bashindzhagyan, G. L.; Batkov, K. E.; Chang, J.; Christl, M.; Fazely, A. R.; Ganel, O.; Gunasingha, R. M.

2004-01-01

The Advanced Thin Ionization Calorimeter (ATIC) was built for series of long- duration balloon flights in Antarctica. Its main goal is to measure energy spectra of cosmic ray nuclei from protons up to iron nuclei over a wide energy range from 30 GeV up to 100 TeV. The ATIC balloon experiment had its first, test flight that lasted for 16 days from 28 Dec 2000 to 13 Jan 2OO1 around the continent. The ATIC spectrometer consists of a fully active BGO calorimeter, scintillator hodoscopes and a silicon matrix. The silicon matrix, consisting of 4480 pixels, was used as a charge detector in the experiment. About 25 million cosmic ray events were detected during the flight. In the paper, the charge spectrum obtained with the silicon matrix is analyzed.

The University of Chicago cosmic ray electrons and nuclei experiment on the H spacecraft

NASA Technical Reports Server (NTRS)

Meyer, P.; Evenson, P.

1978-01-01

The University of Chicago instrument on the Heliocentric spacecraft (MEH experiment) will measure the energy spectrum of cosmic electrons in the range 5-400 MeV. In addition, the energy spectra and relative abundances of nuclei from protons to the iron group, with energies ranging from 30 MeV/n to 15 GeV/n, will be determined. Primary scientific objectives involve the study of the long and short term variability of these components as a probe of the structure of the heliosphere. Particles are identified by multiparameter analysis using the pulse height analyzed signals from eight active detectors - silicon solid state, plastic and crystal scintillators are solid and gas Cerenkov counters. Data return is optimized by a three level priority logic scheme.

Measurement of Cosmic Ray and Trapped Proton LET Spectra on the STS-95 HOST Mission

NASA Astrophysics Data System (ADS)

Stassinopoulos, E. G.; Barth, J. L.; Stauffer, C. A.

2017-08-01

This paper reports on in situ measurements of the linear energy transfer spectra of galactic cosmic rays and their progeny and of trapped Van Allen belt protons as recorded by a pulse height analyzer (PHA) radiation spectrometer which flew on the STS-95 DISCOVERY mission on the Hubble Orbital Systems Test cradle. The shuttle was launched on October 29, 1998 and had a mission duration of 8.5 days during the minimum phase of the solar activity cycle. The orbit of the STS-95 was about 550 km altitude and 28.5° inclination. Close agreement was seen between radiation environment model predictions and the measurements of the PHA. Agreement is obtained by considering the directionality of the radiation interacting with the shuttle structure.

Searches for cosmic-ray electron anisotropies with the Fermi Large Area Telescope

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

Ackermann, M.; Ajello, M.; Bechtol, K.

The Large Area Telescope on board the Fermi satellite (Fermi LAT) detected more than 1.6x10{sup 6} cosmic-ray electrons/positrons with energies above 60 GeV during its first year of operation. The arrival directions of these events were searched for anisotropies of angular scale extending from {approx}10 deg. up to 90 deg., and of minimum energy extending from 60 GeV up to 480 GeV. Two independent techniques were used to search for anisotropies, both resulting in null results. Upper limits on the degree of the anisotropy were set that depended on the analyzed energy range and on the anisotropy's angular scale. Themore » upper limits for a dipole anisotropy ranged from {approx}0.5% to {approx}10%.« less

Searches for cosmic-ray electron anisotropies with the Fermi Large Area Telescope

DOE PAGES

Ackermann, M.

2010-11-01

The Large Area Telescope on board the Fermi satellite (Fermi LAT) detected more than 1.6 × 10 6 cosmic-ray electrons/positrons with energies above 60 GeV during its first year of operation. The arrival directions of these events were searched for anisotropies of angular scale extending from ~ 10 ° up to 90°, and of minimum energy extending from 60 GeV up to 480 GeV. Two independent techniques were used to search for anisotropies, both resulting in null results. Upper limits on the degree of the anisotropy were set that depended on the analyzed energy range and on the anisotropy’s angularmore » scale. The upper limits for a dipole anisotropy ranged from ~ 0.5 % to ~ 10 % .« less

Electric currents in cosmic plasmas

NASA Technical Reports Server (NTRS)

Alfven, H.

1977-01-01

It is suggested that dualism is essential for the physics of cosmic plasmas, that is, that some phenomena should be described by a magnetic field formalism, and others by an electric current formalism. While in earlier work the magnetic field aspect has dominated, at present there is a systematic exploration of the particle (or current) aspect. A number of phenomena which can be understood only from the particle aspect are surveyed. Topics include the formation of electric double layers, the origin of 'explosive' events like magnetic substorms and solar flares, and the transfer of energy from one region to another. A method for exploring many of these phenomena is to draw the electric circuit in which the current flows and then study its properties. A number of simple circuits are analyzed in this way.

IIaO ultraviolet and nuclear emulsion films responses to orbital flights on STS-3, STS-7, STS-8, and STS-40

NASA Technical Reports Server (NTRS)

Hammond, E. C., Jr.; Peters, K. A.; Blake, S. M.; Bailey, Y.; Johnson, D.; Robancho, S.; Stober, A.

1992-01-01

Two types of film were flown on STS-40 space shuttle mission in June 1991. The IIaO special purpose ultraviolet film showed continued desensitization because of various thermal and cosmic ray interactions. The films were exposed to the space orbital environment for 9 days. There were several built-in launch pad delays of the shuttle mission. However, there was adequate monitoring of the temperature variations on board the shuttle that allowed for adequate knowledge of the thermal film history. This IIaO film was flown on the ASTRO I mission and is currently slated for use with the ASTRO II mission. A 50 micron thick IIIford Nuclear emulsion film was also placed on a 175 micron polyester base. The exposure to space produced several cosmic ray interactions that were analyzed and measured using Digital Image Processing techniques. This same nuclear emulsion film was flown on STS-8 and produced a similar number of cosmic ray and thermal interactions. From previous experiments of film using various laboratory electromagnetic radiation sources (e.g., alpha, beta, and neutron particles), we have been able to infer the possible oribtal interactions of both IIaO and nuclear emulsion films. The characteristic responses of IIaO on STS-40 compared favorably to the results obtained from previous STS-7 and STS-8 gas can experiments. The results indicate sufficient evidence correlating increased density on the film with possible cosmic ray, thermal and shuttle out gassing interactions.

Analyzing the User Behavior toward Electronic Commerce Stimuli.

PubMed

Lorenzo-Romero, Carlota; Alarcón-Del-Amo, María-Del-Carmen; Gómez-Borja, Miguel-Ángel

2016-01-01

Based on the Stimulus-Organism-Response paradigm this research analyzes the main differences between the effects of two types of web technologies: Verbal web technology (i.e., navigational structure as utilitarian stimulus) versus non-verbal web technology (music and presentation of products as hedonic stimuli). Specific webmosphere stimuli have not been examined yet as separate variables and their impact on internal and behavioral responses seems unknown. Therefore, the objective of this research consists in analyzing the impact of these web technologies -which constitute the web atmosphere or webmosphere of a website- on shopping human behavior (i.e., users' internal states -affective, cognitive, and satisfaction- and behavioral responses - approach responses, and real shopping outcomes-) within the retail online store created by computer, taking into account some mediator variables (i.e., involvement, atmospheric responsiveness, and perceived risk). A 2 ("free" versus "hierarchical" navigational structure) × 2 ("on" versus "off" music) × 2 ("moving" versus "static" images) between-subjects computer experimental design is used to test empirically this research. In addition, an integrated methodology was developed allowing the simulation, tracking and recording of virtual user behavior within an online shopping environment. As main conclusion, this study suggests that the positive responses of online consumers might increase when they are allowed to freely navigate the online stores and their experience is enriched by animate gifts and music background. The effect caused by mediator variables modifies relatively the final shopping human behavior.

A primer on theory-driven web scraping: Automatic extraction of big data from the Internet for use in psychological research.

PubMed

Landers, Richard N; Brusso, Robert C; Cavanaugh, Katelyn J; Collmus, Andrew B

2016-12-01

The term big data encompasses a wide range of approaches of collecting and analyzing data in ways that were not possible before the era of modern personal computing. One approach to big data of great potential to psychologists is web scraping, which involves the automated collection of information from webpages. Although web scraping can create massive big datasets with tens of thousands of variables, it can also be used to create modestly sized, more manageable datasets with tens of variables but hundreds of thousands of cases, well within the skillset of most psychologists to analyze, in a matter of hours. In this article, we demystify web scraping methods as currently used to examine research questions of interest to psychologists. First, we introduce an approach called theory-driven web scraping in which the choice to use web-based big data must follow substantive theory. Second, we introduce data source theories , a term used to describe the assumptions a researcher must make about a prospective big data source in order to meaningfully scrape data from it. Critically, researchers must derive specific hypotheses to be tested based upon their data source theory, and if these hypotheses are not empirically supported, plans to use that data source should be changed or eliminated. Third, we provide a case study and sample code in Python demonstrating how web scraping can be conducted to collect big data along with links to a web tutorial designed for psychologists. Fourth, we describe a 4-step process to be followed in web scraping projects. Fifth and finally, we discuss legal, practical and ethical concerns faced when conducting web scraping projects. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

The WebCam vs. the Particle Beam: A CRaTER Visualization of the Effects of Radiation

NASA Astrophysics Data System (ADS)

Case, A. W.; Gross, N. A.; Spence, H. E.

2008-12-01

The term "radiation" can cause significant anxiety to a general audience in part because of the associated health risks, but also because of lack of a conceptual framework about the nature of radiation. A visual depiction of radiation may go a long way towards providing just such a framework. The CRaTER Team had an opportunity to create just such a video. The Cosmic Ray Telescope for the Effects of Radiation (CRaTER) is a radiation instrument that will fly on the Lunar Reconnaissance Orbiter (LRO) and is designed to determine the effects of energetic particles on living tissue. In order to calibrate CRaTER and characterize its reaction to various radiation environments, the CRaTER team has used particle beam facilities include the Proton Radiation Therapy Facility at Massachusetts General Hospital (MGH). During one of the sessions at MGH, the team placed an off the shelf web camera into the beam and recorded the visual effects. This video recording was used as the basis for an edited video describing what was done and the results. The hope is that this video will provide a general audience with a visual framework for the nature and effects of radiation

The case for electron re-acceleration at galaxy cluster shocks

NASA Astrophysics Data System (ADS)

van Weeren, Reinout J.; Andrade-Santos, Felipe; Dawson, William A.; Golovich, Nathan; Lal, Dharam V.; Kang, Hyesung; Ryu, Dongsu; Brìggen, Marcus; Ogrean, Georgiana A.; Forman, William R.; Jones, Christine; Placco, Vinicius M.; Santucci, Rafael M.; Wittman, David; Jee, M. James; Kraft, Ralph P.; Sobral, David; Stroe, Andra; Fogarty, Kevin

2017-01-01

On the largest scales, the Universe consists of voids and filaments making up the cosmic web. Galaxy clusters are located at the knots in this web, at the intersection of filaments. Clusters grow through accretion from these large-scale filaments and by mergers with other clusters and groups. In a growing number of galaxy clusters, elongated Mpc-sized radio sources have been found1,2 . Also known as radio relics, these regions of diffuse radio emission are thought to trace relativistic electrons in the intracluster plasma accelerated by low-Mach-number shocks generated by cluster-cluster merger events 3 . A long-standing problem is how low-Mach-number shocks can accelerate electrons so efficiently to explain the observed radio relics. Here, we report the discovery of a direct connection between a radio relic and a radio galaxy in the merging galaxy cluster Abell 3411-3412 by combining radio, X-ray and optical observations. This discovery indicates that fossil relativistic electrons from active galactic nuclei are re-accelerated at cluster shocks. It also implies that radio galaxies play an important role in governing the non-thermal component of the intracluster medium in merging clusters.

The case for electron re-acceleration at galaxy cluster shocks

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

van Weeren, Reinout J.; Andrade-Santos, Felipe; Dawson, William A.

On the largest scales, the Universe consists of voids and filaments making up the cosmic web. Galaxy clusters are located at the knots in this web, at the intersection of filaments. Clusters grow through accretion from these large-scale filaments and by mergers with other clusters and groups. In a growing number of galaxy clusters, elongated Mpc-sized radio sources have been found. Also known as radio relics, these regions of diffuse radio emission are thought to trace relativistic electrons in the intracluster plasma accelerated by low-Mach-number shocks generated by cluster–cluster merger events. A long-standing problem is how low-Mach-number shocks can acceleratemore » electrons so efficiently to explain the observed radio relics. Here, we report the discovery of a direct connection between a radio relic and a radio galaxy in the merging galaxy cluster Abell 3411–3412 by combining radio, X-ray and optical observations. This discovery indicates that fossil relativistic electrons from active galactic nuclei are re-accelerated at cluster shocks. Lastly, it also implies that radio galaxies play an important role in governing the non-thermal component of the intracluster medium in merging clusters.« less

The case for electron re-acceleration at galaxy cluster shocks

DOE PAGES

van Weeren, Reinout J.; Andrade-Santos, Felipe; Dawson, William A.; ...

2017-01-04

On the largest scales, the Universe consists of voids and filaments making up the cosmic web. Galaxy clusters are located at the knots in this web, at the intersection of filaments. Clusters grow through accretion from these large-scale filaments and by mergers with other clusters and groups. In a growing number of galaxy clusters, elongated Mpc-sized radio sources have been found. Also known as radio relics, these regions of diffuse radio emission are thought to trace relativistic electrons in the intracluster plasma accelerated by low-Mach-number shocks generated by cluster–cluster merger events. A long-standing problem is how low-Mach-number shocks can acceleratemore » electrons so efficiently to explain the observed radio relics. Here, we report the discovery of a direct connection between a radio relic and a radio galaxy in the merging galaxy cluster Abell 3411–3412 by combining radio, X-ray and optical observations. This discovery indicates that fossil relativistic electrons from active galactic nuclei are re-accelerated at cluster shocks. Lastly, it also implies that radio galaxies play an important role in governing the non-thermal component of the intracluster medium in merging clusters.« less

c-Mantic: A Cytoscape plugin for Semantic Web

EPA Science Inventory

Semantic Web tools can streamline the process of storing, analyzing and sharing biological information. Visualization is important for communicating such complex biological relationships. Here we use the flexibility and speed of the Cytoscape platform to interactively visualize s...

Academic Job Placements in Library and Information Science Field: A Case Study Performed on ALISE Web-Based Postings

ERIC Educational Resources Information Center

Abouserie, Hossam Eldin Mohamed Refaat

2010-01-01

The study investigated and analyzed the state of academic web-based job announcements in Library and Information Science Field. The purpose of study was to get in depth understanding about main characteristics and trends of academic job market in Library and Information science field. The study focused on web-based version announcement as it was…

Using Web Maps to Analyze the Construction of Global Scale Cognitive Maps

ERIC Educational Resources Information Center

Pingel, Thomas J.

2018-01-01

Game-based Web sites and applications are changing the ways in which students learn the world map. In this study, a Web map-based digital learning tool was used as a study aid for a university-level geography course in order to examine the way in which global scale cognitive maps are constructed. A network analysis revealed that clicks were…

Evaluation of a new website design for iwantthekit for chlamydia, gonorrhea, and trichomonas screening.

PubMed

Kuder, Margaret; Goheen, Mary Jett; Dize, Laura; Barnes, Mathilda; Gaydos, Charlotte A

2015-05-01

The www.iwantthekit.org provides Internet-based, at-home sexually transmitted infection screening. The Web site implemented an automated test result access system. To evaluate potential deleterious effects of the new system, we analyzed demographics, Web site usage, and treatment. The post-Web site design captured more participant information and no decrease in requests, kit return, or treatment adherence.

Pioneer 10 and 11 Data Analysis

NASA Technical Reports Server (NTRS)

Fillius, Walker

1997-01-01

This report finishes the work of NASA Grant NAS2-153, which supported data analysis for the UCSD instruments on Pioneers 10 and 11. The data analyzed under this grant span 22 years of interplanetary measurements in the inner and outer heliosphere. The UCSD instruments made their mark in cosmic ray research based upon their high energy thresholds, directional responses, and reliable data streams. one of their primary scientific objectives concerns the size, configuration, and time behavior of the heliosphere. The size scale is inferred from the radial intensity gradient, which is measured between the two spacecraft and extrapolated to interstellar intensity levels at the cosmic ray modulation boundary. This boundary still eludes us, and its position, motion, and the best method of extrapolation are ongoing problems. Current projections place the boundary beyond 100 AU, which may be beyond the termination shock, and raises the question of possible modulation in the heliosheath. Probably our only hope of seeing this region in the immediate future rides on the possibility that the boundary will move inward. Our instruments have recorded many Forbush, or transient, decreases in the outer heliosphere. These observations led us to a model that attributes many of the decreases to solar wind stream-stream interactions, and relates the cosmic ray variations to the locally observed magnetic field magnitude. As the cosmic ray variations in this model result only from topological changes in the modulation integral, the model is a tool for studying the possibility that the 11 year cosmic ray modulation cycle can be accounted for by a superposition of Forbush decreases. The cosmic ray angular distribution function is measurable, given a good telemetry rate, by the UCSD Cerenkov detector which counts particles of energy greater than 500 MeV/n. We obtained statistically significant samples from 1 to 9 AU, at 13 AU, and at 34 AU. The anisotropy tends to be a few tenths of a per cent at all radial distances. A quasiperiodic variation in the east-west anisotropy with period of about 50 days remains unexplained.

ProstateAnalyzer: Web-based medical application for the management of prostate cancer using multiparametric MR imaging.

PubMed

Mata, Christian; Walker, Paul M; Oliver, Arnau; Brunotte, François; Martí, Joan; Lalande, Alain

2016-01-01

In this paper, we present ProstateAnalyzer, a new web-based medical tool for prostate cancer diagnosis. ProstateAnalyzer allows the visualization and analysis of magnetic resonance images (MRI) in a single framework. ProstateAnalyzer recovers the data from a PACS server and displays all the associated MRI images in the same framework, usually consisting of 3D T2-weighted imaging for anatomy, dynamic contrast-enhanced MRI for perfusion, diffusion-weighted imaging in the form of an apparent diffusion coefficient (ADC) map and MR Spectroscopy. ProstateAnalyzer allows annotating regions of interest in a sequence and propagates them to the others. From a representative case, the results using the four visualization platforms are fully detailed, showing the interaction among them. The tool has been implemented as a Java-based applet application to facilitate the portability of the tool to the different computer architectures and software and allowing the possibility to work remotely via the web. ProstateAnalyzer enables experts to manage prostate cancer patient data set more efficiently. The tool allows delineating annotations by experts and displays all the required information for use in diagnosis. According to the current European Society of Urogenital Radiology guidelines, it also includes the PI-RADS structured reporting scheme.

Location-based Web Search

NASA Astrophysics Data System (ADS)

Ahlers, Dirk; Boll, Susanne

In recent years, the relation of Web information to a physical location has gained much attention. However, Web content today often carries only an implicit relation to a location. In this chapter, we present a novel location-based search engine that automatically derives spatial context from unstructured Web resources and allows for location-based search: our focused crawler applies heuristics to crawl and analyze Web pages that have a high probability of carrying a spatial relation to a certain region or place; the location extractor identifies the actual location information from the pages; our indexer assigns a geo-context to the pages and makes them available for a later spatial Web search. We illustrate the usage of our spatial Web search for location-based applications that provide information not only right-in-time but also right-on-the-spot.

Analysis of castellated steel beam with oval openings

NASA Astrophysics Data System (ADS)

Tudjono, S.; Sunarto; Han, A. L.

2017-11-01

A castellated steel beam is per definition a wide flange (WF) or I shaped steel profile with openings, to reduce self-weight and improve the effectiveness in terms of material use. Recently, extensive study on these castellated steel beams has been conducted, involving different shapes in web openings. The main goal of these research works was to evaluate and analyze its optimum opening sizes and shapes configuration. More in-depth research work to the behavior and the influence of holes to WF beams need to be conducted. In this paper, an oval shaped web opening is chosen as alternate. The study involves a modification in the variation of oval web openings both in the horizontally and vertically direction. An experimental and numerical study based on the finite element method conducted with the Abaqus/CAE 6.12 software is used to analyze the buckling behavior of the web. The obtained results from the experimental test specimens are in good agreement with the obtained results from the finite element analysis. Furthermore, the numerical model can be expanded to be used as analyzing tool in evaluating and studying the effect and influencing factors of a variation in opening’s parameters.

Development of Web Interfaces for Analysis Codes

NASA Astrophysics Data System (ADS)

Emoto, M.; Watanabe, T.; Funaba, H.; Murakami, S.; Nagayama, Y.; Kawahata, K.

Several codes have been developed to analyze plasma physics. However, most of them are developed to run on supercomputers. Therefore, users who typically use personal computers (PCs) find it difficult to use these codes. In order to facilitate the widespread use of these codes, a user-friendly interface is required. The authors propose Web interfaces for these codes. To demonstrate the usefulness of this approach, the authors developed Web interfaces for two analysis codes. One of them is for FIT developed by Murakami. This code is used to analyze the NBI heat deposition, etc. Because it requires electron density profiles, electron temperatures, and ion temperatures as polynomial expressions, those unfamiliar with the experiments find it difficult to use this code, especially visitors from other institutes. The second one is for visualizing the lines of force in the LHD (large helical device) developed by Watanabe. This code is used to analyze the interference caused by the lines of force resulting from the various structures installed in the vacuum vessel of the LHD. This code runs on PCs; however, it requires that the necessary parameters be edited manually. Using these Web interfaces, users can execute these codes interactively.

Computer Technology for Industry

NASA Technical Reports Server (NTRS)

1982-01-01

Shell Oil Company used a COSMIC program, called VISCEL to insure the accuracy of the company's new computer code for analyzing polymers, and chemical compounds. Shell reported that there were no other programs available that could provide the necessary calculations. Shell produces chemicals for plastic products used in the manufacture of automobiles, housewares, appliances, film, textiles, electronic equipment and furniture.

Evaluation of a web-based family medicine case library for self-directed learning in a third-year clerkship.

PubMed

Morrow, Jay B; Sepdham, Dan; Snell, Laura; Lindeman, Carolyn; Dobbie, Alison

2010-01-01

Web-based cases are well accepted by medical students and enable faculty to deliver equivalent educational experiences to all students. A 2009 literature search revealed no study investigating student use patterns of Web-based case libraries for self-directed learning. We investigated third-year students' use of a Web-based case program for self-directed learning in a family medicine clerkship. We analyzed Design A Case usage patterns of 210 medical students during academic year 2008--2009. We compared board score differences between these students and those from the previous 5 years who did not use Design A Case. We analyzed data from a 13-item survey, administered to a subgroup of 85 students, about the strengths, weaknesses, and acceptability of the program. Students completed, on average, four cases, which was beyond the requirement of three. They reported that the content was highly relevant to cases they saw in clinic. Almost 75% preferred the self-directed Web-based learning over didactics, and most (64%) felt they learned more electronically. Use of the cases was associated with equivalent Board scores versus didactic lectures. In our setting, self-directed learning using a Web-based case program was highly acceptable to students. Web-based cases may provide an option for family medicine educators who wish to deliver equivalent educational experiences across sites.

Accelerating dark energy cosmological model in two fluids with hybrid scale factor

NASA Astrophysics Data System (ADS)

Mishra, B.; Sahoo, P. K.; Ray, Pratik P.

In this paper, we have investigated the anisotropic behavior of the accelerating universe in Bianchi V spacetime in the framework of General Relativity (GR). The matter field we have considered is of two non-interacting fluids, i.e. the usual string fluid and dark energy (DE) fluid. In order to represent the pressure anisotropy, the skewness parameters are introduced along three different spatial directions. To achieve a physically realistic solutions to the field equations, we have considered a scale factor, known as hybrid scale factor, which is generated by a time-varying deceleration parameter. This simulates a cosmic transition from early deceleration to late time acceleration. It is observed that the string fluid dominates the universe at early deceleration phase but does not affect nature of cosmic dynamics substantially at late phase, whereas the DE fluid dominates the universe in present time, which is in accordance with the observations results. Hence, we analyzed here the role of two fluids in the transitional phases of universe with respect to time which depicts the reason behind the cosmic expansion and DE. The role of DE with variable equation of state parameter (EoS) and skewness parameters, is also discussed along with physical and geometrical properties.

Cosmological applications of singular hypersurfaces in general relativity

NASA Astrophysics Data System (ADS)

Laguna-Castillo, Pablo

Three applications to cosmology of surface layers, based on Israel's formalism of singular hypersurfaces and thin shells in general relativity, are presented. Einstein's field equations are analyzed in the presence of a bubble nucleated in vacuum phase transitions within the context of the old inflationary universe scenario. The evolution of a bubble with vanishing surface energy density is studied. It is found that such bubbles lead to a worm-hole matching. Next, the observable four-dimensional universe is considered as a singular hypersurface of discontinuity embedded in a five-dimensional Kaluza-Klein cosmology. It is possible to rewrite the projected five-dimensional Einstein equations on the surface layer in a similar way to the four-dimensional Robertson-Walker cosmology equations. Next, a model is described for an infinite-length, straight U(1) cosmic string as a cylindrical, singular shell enclosing a region of false vacuum. A set of equations is introduced which are required to develop a three-dimensional computer code whose purpose is to study the process of intercommuting cosmic strings with the inclusion of gravitational effects. The outcome is evolution and constraint equations for the gravitational, scalar and gauge field of two initially separated, perpendicular, cosmic strings.

Thin and thick cloud top height retrieval algorithm with the Infrared Camera and LIDAR of the JEM-EUSO Space Mission

NASA Astrophysics Data System (ADS)

Sáez-Cano, G.; Morales de los Ríos, J. A.; del Peral, L.; Neronov, A.; Wada, S.; Rodríguez Frías, M. D.

2015-03-01

The origin of cosmic rays have remained a mistery for more than a century. JEM-EUSO is a pioneer space-based telescope that will be located at the International Space Station (ISS) and its aim is to detect Ultra High Energy Cosmic Rays (UHECR) and Extremely High Energy Cosmic Rays (EHECR) by observing the atmosphere. Unlike ground-based telescopes, JEM-EUSO will observe from upwards, and therefore, for a properly UHECR reconstruction under cloudy conditions, a key element of JEM-EUSO is an Atmospheric Monitoring System (AMS). This AMS consists of a space qualified bi-spectral Infrared Camera, that will provide the cloud coverage and cloud top height in the JEM-EUSO Field of View (FoV) and a LIDAR, that will measure the atmospheric optical depth in the direction it has been shot. In this paper we will explain the effects of clouds for the determination of the UHECR arrival direction. Moreover, since the cloud top height retrieval is crucial to analyze the UHECR and EHECR events under cloudy conditions, the retrieval algorithm that fulfills the technical requierements of the Infrared Camera of JEM-EUSO to reconstruct the cloud top height is presently reported.

Cosmic Ray Tests of Gas Electron Multipliers

NASA Astrophysics Data System (ADS)

Harris, Letrell; Kohl, Michael; Super Bigbite Spectrometer Collaboration; MUSE Collaboration; Hampton University Collaboration; DarkLight Collaboration

2017-09-01

The Super Bigbite Spectrometer (SBS) collaboration at Jefferson Laboratory (Jlab) is conducting an experimental program to measure the elastic form factors of nucleons. In association with Jlab, SBS Gas Electron Multipliers (GEMs) have been constructed by the University of Virginia (back trackers) and INFN in Italy (front trackers). The SBS GEMs measuring 40 × 150 cm2 (front trackers) and 60 × 200 cm2 (back trackers) in surface area are in the process of being conditioned and analyzed for tracking efficiency using cosmic rays in a clean room test lab before further assembly in the fall. These GEMs will be used to track the path of particles scattered off nuclear targets. Scintillators are placed both above and below GEM stacks to trigger a readout. In addition, Hampton University has also constructed a set of 10 × 10 cm2 GEMs originally for the OLYMPUS experiment at DESY in Germany, which are now being used for both the MUSE experiment at Paul Scherrer Institute (PSI) in Switzerland and the DarkLight experiment at Jlab's Low Energy Recirculatory Facility (LERF), where they are in the process of being characterized with cosmic rays. Jefferson Laboratory. This work has been supported by Jefferson Laboratory.

Noble gas isotopic composition, cosmic ray exposure history, and terrestrial age of the meteorite Allan Hills A81005 from the moon

NASA Astrophysics Data System (ADS)

Eugster, O.; Geiss, J.; Kraehenbuehl, U.; Niedermann, S.

1986-06-01

A comprehensive study of the elemental and isotopic abundances of the noble gases He, Ne, Ar, Kr, and Xe in the meteorite Allan Hills A81005 from the moon is presented. In addition to a bulk sample, five grain-size fractions were analyzed. Chemical abundances relevant to the interpretation of the cosmic-ray-produced noble gases were determined and indicate that the grain size fractions are chemically uniform. Except for the fact that the trapped noble gas concentrations appear to be grain size correlated, the isotopic and elemental pattern of the trapped solar wind noble gases in A81005 are very similar to those observed in lunar soils and breccias. The A81005 material resided during (580 + or - 180) Myr in the nuclear active zone of the lunar regolith at an average shielding depth of about 40 g/sq cm. From literature data, it is concluded that the moon-earth transit time lasted less than a few million years. Finally, A81005 was captured by the earth more than 140,000 years ago, as indicated by the abundance of cosmic-ray-produced Kr-81.

CosmicSIG science and plans

NASA Astrophysics Data System (ADS)

Olinto, Angela V.

2014-03-01

Recent activities of the Cosmic Ray Science Interest Group (CosmicSIG) of the Physics of the Cosmos PAG will be reviewed. CosmicSIG was formed to provide an assessment to NASA HQ and the PCOS program office of the status of current and future missions in the area of cosmic-ray astrophysics. CosmicSIG also strives to act as a focal point and forum for the cosmic ray community.

Development of deterministic transport methods for low energy neutrons for shielding in space

NASA Technical Reports Server (NTRS)

Ganapol, Barry

1993-01-01

Transport of low energy neutrons associated with the galactic cosmic ray cascade is analyzed in this dissertation. A benchmark quality analytical algorithm is demonstrated for use with BRYNTRN, a computer program written by the High Energy Physics Division of NASA Langley Research Center, which is used to design and analyze shielding against the radiation created by the cascade. BRYNTRN uses numerical methods to solve the integral transport equations for baryons with the straight-ahead approximation, and numerical and empirical methods to generate the interaction probabilities. The straight-ahead approximation is adequate for charged particles, but not for neutrons. As NASA Langley improves BRYNTRN to include low energy neutrons, a benchmark quality solution is needed for comparison. The neutron transport algorithm demonstrated in this dissertation uses the closed-form Green's function solution to the galactic cosmic ray cascade transport equations to generate a source of neutrons. A basis function expansion for finite heterogeneous and semi-infinite homogeneous slabs with multiple energy groups and isotropic scattering is used to generate neutron fluxes resulting from the cascade. This method, called the FN method, is used to solve the neutral particle linear Boltzmann transport equation. As a demonstration of the algorithm coded in the programs MGSLAB and MGSEMI, neutron and ion fluxes are shown for a beam of fluorine ions at 1000 MeV per nucleon incident on semi-infinite and finite aluminum slabs. Also, to demonstrate that the shielding effectiveness against the radiation from the galactic cosmic ray cascade is not directly proportional to shield thickness, a graph of transmitted total neutron scalar flux versus slab thickness is shown. A simple model based on the nuclear liquid drop assumption is used to generate cross sections for the galactic cosmic ray cascade. The ENDF/B V database is used to generate the total and scattering cross sections for neutrons in aluminum. As an external verification, the results from MGSLAB and MGSEMI were compared to ANISN/PC, a routinely used neutron transport code, showing excellent agreement. In an application to an aluminum shield, the FN method seems to generate reasonable results.

Use and abuse of mixing models (MixSIAR)

EPA Science Inventory

Background/Question/MethodsCharacterizing trophic links in food webs is a fundamental ecological question. In our efforts to quantify energy flow through food webs, ecologists have increasingly used mixing models to analyze biological tracer data, often from stable isotopes. Whil...

The use of the World Wide Web by medical journals in 2003 and 2005: an observational study.

PubMed

Schriger, David L; Ouk, Sripha; Altman, Douglas G

2007-01-01

The 2- to 6-page print journal article has been the standard for 200 years, yet this format severely limits the amount of detailed information that can be conveyed. The World Wide Web provides a low-cost option for posting extended text and supplementary information. It also can enhance the experience of journal editors, reviewers, readers, and authors through added functionality (eg, online submission and peer review, postpublication critique, and e-mail notification of table of contents.) Our aim was to characterize ways that journals were using the World Wide Web in 2005 and note changes since 2003. We analyzed the Web sites of 138 high-impact print journals in 3 ways. First, we compared the print and Web versions of March 2003 and 2005 issues of 28 journals (20 of which were randomly selected from the 138) to determine how often articles were published Web only and how often print articles were augmented by Web-only supplements. Second, we examined what functions were offered by each journal Web site. Third, for journals that offered Web pages for reader commentary about each article, we analyzed the number of comments and characterized these comments. Fifty-six articles (7%) in 5 journals were Web only. Thirteen of the 28 journals had no supplementary online content. By 2005, several journals were including Web-only supplements in >20% of their papers. Supplementary methods, tables, and figures predominated. The use of supplementary material increased by 5% from 2% to 7% in the 20-journal random sample from 2003 to 2005. Web sites had similar functionality with an emphasis on linking each article to related material and e-mailing readers about activity related to each article. There was little evidence of journals using the Web to provide readers an interactive experience with the data or with each other. Seventeen of the 138 journals offered rapid-response pages. Only 18% of eligible articles had any comments after 5 months. Journal Web sites offer similar functionality. The use of online-only articles and online-only supplements is increasing.

Bad on the net, or bipolars' lives on the web: analyzing discussion web pages for individuals with bipolar affective disorder.

PubMed

Latalova, Klara; Prasko, Jan; Kamaradova, Dana; Ivanova, Katerina; Jurickova, Lubica

2014-01-01

The main therapeutic approach in the treatment of bipolar affective disorder is the administration of drugs. The effectiveness of this approach can be increased by specific psychotherapeutic interventions. There is not much knowledge about self-help initiatives in this field. Anonymous internet communication may be beneficial, regardless of the fact that it is non-professional. It offers a chance to confide and share symptoms with other patients, to open up for persons with feelings of shame, and to obtain relevant information without having a direct contact with an expert. Qualitative analysis of web discussions used by patients with bipolar disorder in Czech language was performed. Using key words "diskuze" (discussion), "maniodeprese" (manic depression) and "bipolární porucha" (bipolar disorder), 8 discussions were found, but only 3 of them were anonymous and non-professional. Individual discussion entries were analyzed for basic categories or subcategories, and these were subsequently assessed so that their relationships could be better understood. A total of 436 entries from 3 discussion web pages were analyzed. Subsequently, six categories were identified (participant, diagnosis, relationships, communication, topic and treatment), each having 5-12 subcategories. These were analyzed in terms of relationships and patterns. Czech discussion web pages for people suffering from bipolar disorder are a lively community of users supporting each other, that may be characterized as a compact body open to newcomers. They seem to fulfill patients' needs that are not fully met by health care services. It also has a "self-cleaning" ability, effectively dealing with posts that are inappropriate, provocative, criticizing, aggressive or meaningless.

Specification Patent Management for Web Application Platform Ecosystem

NASA Astrophysics Data System (ADS)

Fukami, Yoshiaki; Isshiki, Masao; Takeda, Hideaki; Ohmukai, Ikki; Kokuryo, Jiro

Diversified usage of web applications has encouraged disintegration of web platform into management of identification and applications. Users make use of various kinds of data linked to their identity with multiple applications on certain social web platforms such as Facebook or MySpace. There has emerged competition among web application platforms. Platformers can design relationship with developers by controlling patent of their own specification and adopt open technologies developed external organizations. Platformers choose a way to open according to feature of the specification and their position. Patent management of specification come to be a key success factor to build competitive web application platforms. Each way to attract external developers such as standardization, open source has not discussed and analyzed all together.

Usability Evaluation of Public Web Mapping Sites

NASA Astrophysics Data System (ADS)

Wang, C.

2014-04-01

Web mapping sites are interactive maps that are accessed via Webpages. With the rapid development of Internet and Geographic Information System (GIS) field, public web mapping sites are not foreign to people. Nowadays, people use these web mapping sites for various reasons, in that increasing maps and related map services of web mapping sites are freely available for end users. Thus, increased users of web mapping sites led to more usability studies. Usability Engineering (UE), for instance, is an approach for analyzing and improving the usability of websites through examining and evaluating an interface. In this research, UE method was employed to explore usability problems of four public web mapping sites, analyze the problems quantitatively and provide guidelines for future design based on the test results. Firstly, the development progress for usability studies were described, and simultaneously several usability evaluation methods such as Usability Engineering (UE), User-Centered Design (UCD) and Human-Computer Interaction (HCI) were generally introduced. Then the method and procedure of experiments for the usability test were presented in detail. In this usability evaluation experiment, four public web mapping sites (Google Maps, Bing maps, Mapquest, Yahoo Maps) were chosen as the testing websites. And 42 people, who having different GIS skills (test users or experts), gender (male or female), age and nationality, participated in this test to complete the several test tasks in different teams. The test comprised three parts: a pretest background information questionnaire, several test tasks for quantitative statistics and progress analysis, and a posttest questionnaire. The pretest and posttest questionnaires focused on gaining the verbal explanation of their actions qualitatively. And the design for test tasks targeted at gathering quantitative data for the errors and problems of the websites. Then, the results mainly from the test part were analyzed. The success rate from different public web mapping sites was calculated and compared, and displayed by the means of diagram. And the answers from questionnaires were also classified and organized in this part. Moreover, based on the analysis, this paper expands the discussion about the layout, map visualization, map tools, search logic and etc. Finally, this paper closed with some valuable guidelines and suggestions for the design of public web mapping sites. Also, limitations for this research stated in the end.

Calculation of Cosmic Ray Induced Single Event Upsets: Program CRUP, Cosmic Ray Upset Program

DTIC Science & Technology

1983-09-14

1.., 0 .j ~ u M ~ t R A’- ~~ ’ .~ ; I .: ’ 1 J., ) ’- CALCULATION OF COSMIC RAY INDUCED SINGLE EVEI’o"T UPSETS: PROGRAM CRUP , COSMIC RAY UPSET...neceuety end Identity by blo..;k number) 0Thls report documents PROGR.Al\\1 CRUP , COSMIC RAY UPSET PROGRAM. The computer program calculates cosmic...34. » » •-, " 1 » V »1T"~ Calculation of Cosmic Ray Induced Single Event Upsets: PROGRAM CRUP , COSMIC RAY UPSET PROGRAM I. INTRODUCTION Since the

Web Accessibility of the Higher Education Institute Websites Based on the World Wide Web Consortium and Section 508 of the Rehabilitation Act

ERIC Educational Resources Information Center

Alam, Najma H.

2014-01-01

The problem observed in this study is the low level of compliance of higher education website accessibility with Section 508 of the Rehabilitation Act of 1973. The literature supports the non-compliance of websites with the federal policy in general. Studies were performed to analyze the accessibility of fifty-four sample web pages using automated…

Do infertile women and government staff differ in the evaluation of infertility-related Web sites?

PubMed

Takabayashi, Chikako; Shimada, Keiko

2011-01-01

To investigate the evaluation of local government Web sites carrying information on infertility by infertile women and by government staff. In particular, the study investigated whether the women and staff differed with respect to the information they rate as important and their self-reported satisfaction with the Web sites. Cross-sectional descriptive study. Sixty-two local government staff members, of whom 46 were public health nurses managing subsidy programs for infertility treatment in the Hokuriku region of Japan, and 84 infertile women attending local clinics. We measured the level of satisfaction with the local government Web sites and perceptions about the importance of each type of content. Data were descriptively analyzed, as well as by factor analysis and multiple regression analysis. Local government Web sites were analyzed with respect to information about the treatment, details of the subsidy program, psychological support, and procedures for making a subsidy application. The women rated information on the treatment and details of the subsidy programs as important. There was no difference of satisfaction with the Web sites between the infertile women and the staff. Local government staff need to provide reliable data for women who are seeking information on infertility treatment. © 2011 Wiley Periodicals, Inc.

Impact of Cosmic-Ray Transport on Galactic Winds

NASA Astrophysics Data System (ADS)

Farber, R.; Ruszkowski, M.; Yang, H.-Y. K.; Zweibel, E. G.

2018-04-01

The role of cosmic rays generated by supernovae and young stars has very recently begun to receive significant attention in studies of galaxy formation and evolution due to the realization that cosmic rays can efficiently accelerate galactic winds. Microscopic cosmic-ray transport processes are fundamental for determining the efficiency of cosmic-ray wind driving. Previous studies modeled cosmic-ray transport either via a constant diffusion coefficient or via streaming proportional to the Alfvén speed. However, in predominantly cold, neutral gas, cosmic rays can propagate faster than in the ionized medium, and the effective transport can be substantially larger; i.e., cosmic rays can decouple from the gas. We perform three-dimensional magnetohydrodynamical simulations of patches of galactic disks including the effects of cosmic rays. Our simulations include the decoupling of cosmic rays in the cold, neutral interstellar medium. We find that, compared to the ordinary diffusive cosmic-ray transport case, accounting for the decoupling leads to significantly different wind properties, such as the gas density and temperature, significantly broader spatial distribution of cosmic rays, and higher wind speed. These results have implications for X-ray, γ-ray, and radio emission, and for the magnetization and pollution of the circumgalactic medium by cosmic rays.

The MAJORANA Parts Tracking Database

NASA Astrophysics Data System (ADS)

Abgrall, N.; Aguayo, E.; Avignone, F. T.; Barabash, A. S.; Bertrand, F. E.; Brudanin, V.; Busch, M.; Byram, D.; Caldwell, A. S.; Chan, Y.-D.; Christofferson, C. D.; Combs, D. C.; Cuesta, C.; Detwiler, J. A.; Doe, P. J.; Efremenko, Yu.; Egorov, V.; Ejiri, H.; Elliott, S. R.; 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. Diaz; Leviner, L. E.; Loach, J. C.; MacMullin, J.; Martin, R. D.; Meijer, S. J.; Mertens, S.; Miller, M. L.; Mizouni, L.; Nomachi, M.; Orrell, J. L.; O`Shaughnessy, C.; Overman, N. R.; Petersburg, R.; Phillips, D. G.; Poon, A. W. P.; Pushkin, K.; Radford, D. C.; Rager, J.; Rielage, K.; Robertson, R. G. H.; Romero-Romero, E.; Ronquest, M. C.; Shanks, B.; Shima, T.; Shirchenko, M.; Snavely, K. J.; Snyder, N.; Soin, A.; Suriano, A. M.; Tedeschi, D.; Thompson, J.; Timkin, V.; Tornow, W.; Trimble, J. E.; Varner, R. L.; Vasilyev, S.; Vetter, K.; Vorren, K.; White, B. R.; Wilkerson, J. F.; Wiseman, C.; Xu, W.; Yakushev, E.; Young, A. R.; Yu, C.-H.; Yumatov, V.; Zhitnikov, I.

2015-04-01

The MAJORANA DEMONSTRATOR is an ultra-low background physics experiment searching for the neutrinoless double beta decay of 76Ge. The MAJORANA Parts Tracking Database is used to record the history of components used in the construction of the DEMONSTRATOR. The tracking implementation takes a novel approach based on the schema-free database technology CouchDB. Transportation, storage, and processes undergone by parts such as machining or cleaning are linked to part records. Tracking parts provide a great logistics benefit and an important quality assurance reference during construction. In addition, the location history of parts provides an estimate of their exposure to cosmic radiation. A web application for data entry and a radiation exposure calculator have been developed as tools for achieving the extreme radio-purity required for this rare decay search.

Extreme Mergers from the Massive Cluster Survey

NASA Astrophysics Data System (ADS)

Morris, Roger

2010-09-01

We propose to observe two extraordinary, high-redshift galaxy clusters from the Massive Cluster Survey. Both targets are very rare, triple merger systems (one a nearly co-linear merger), and likely lie at the deepest nodes of the cosmic web. Both targets show multiple strong gravitational lensing arcs in the cluster cores. These targets only possess very short (10ks) Chandra observations, and are unobserved by XMM-Newton. The X-ray data will be used to probe the mass distribution of hot, baryonic gas, and to reveal the details of the merger physics and the process of cluster assembly. We will also search for hints of X-ray emission from filaments between the merging clumps. Subaru and Hubble Space Telescope imaging data are in hand; we request additional HST coverage for one object.

Preparing Colorful Astronomical Images III: Cosmetic Cleaning

NASA Astrophysics Data System (ADS)

Frattare, L. M.; Levay, Z. G.

2003-12-01

We present cosmetic cleaning techniques for use with mainstream graphics software (Adobe Photoshop) to produce presentation-quality images and illustrations from astronomical data. These techniques have been used on numerous images from the Hubble Space Telescope when producing photographic, print and web-based products for news, education and public presentation as well as illustrations for technical publication. We expand on a previous paper to discuss the treatment of various detector-attributed artifacts such as cosmic rays, chip seams, gaps, optical ghosts, diffraction spikes and the like. While Photoshop is not intended for quantitative analysis of full dynamic range data (as are IRAF or IDL, for example), we have had much success applying Photoshop's numerous, versatile tools to final presentation images. Other pixel-to-pixel applications such as filter smoothing and global noise reduction will be discussed.

FAST Mapping of Diffuse HI Gas in the Local Universe

NASA Astrophysics Data System (ADS)

Zhu, M.; Pisano, D. J.; Ai, M.; Jiao, Q.

2016-02-01

We propose to use the Five hundred meter Aperture Spherical radio Telescope (FAST) to map the diffuse intergalactic HI gas in the local universe at column densities of NHI=1018 cm-2 and below. The major science goal is to study gas accretion during galaxy evolution, and trace cosmic web features in the local universe. We disuss the technical feasibilty of such a deep survey, and have conducted test observations with the Arecibo 305 m telescope. Our preliminary results shows that, with about a few thousand hours of observing time, FAST will be able to map several hundred square degree regions at 1 σ of NHI=2×1017 cm-2 level out to a distance of 5-10 Mpc, and with a volume 1000 larger than that of the Local Group.

Searching for intermediate-mass black holes in extremely-metal poor galaxies

NASA Astrophysics Data System (ADS)

Mezcua, Mar

2016-09-01

Extremely metal-poor dwarf galaxies (XMPs) are star-forming, low-mass galaxies with metallicites highly sub-solar. Their regions of star formation could be triggered by the accretion of pristine gas from the cosmic web and harbour Population III stars. XMPs are thus ideal laboratories for searching for the seed black holes or intermediate-mass black holes (IMBHs) that populated the early Universe. The combination of X-ray, radio and optical observations offer the best tool for detecting such IMBHs in the local Universe. We propose Chandra observations of a sample of XMPs whose optical spectra indicate the possible presence of an active black hole of 1e4 - 1e6 Msun. The Chandra data could confirm this and yield the first detection of an IMBH in these type of galaxies.

Advances in instrumentation at the W. M. Keck Observatory

NASA Astrophysics Data System (ADS)

Adkins, Sean M.; Armandroff, Taft E.; Johnson, James; Lewis, Hilton A.; Martin, Christopher; McLean, Ian S.; Wizinowich, Peter

2012-09-01

In this paper we describe both recently completed instrumentation projects and our current development efforts in terms of their role in the strategic plan, the key science areas they address, and their performance as measured or predicted. Projects reaching completion in 2012 include MOSFIRE, a near IR multi-object spectrograph, a laser guide star adaptive optics facility on the Keck I telescope, and an upgrade to the guide camera for the HIRES instrument on Keck I. Projects in development include a new seeing limited integral field spectrograph for the visible wavelength range called the Keck Cosmic Web Imager (KCWI), an upgrade to the telescope control systems on both Keck telescopes, a near-IR tip/tilt sensor for the Keck I adaptive optics system, and a new grating for the OSIRIS integral field spectrograph.

The role of penetrating gas streams in setting the dynamical state of galaxy clusters

NASA Astrophysics Data System (ADS)

Zinger, E.; Dekel, A.; Birnboim, Y.; Kravtsov, A.; Nagai, D.

2016-09-01

We utilize cosmological simulations of 16 galaxy clusters at redshifts z = 0 and z = 0.6 to study the effect of inflowing streams on the properties of the X-ray emitting intracluster medium. We find that the mass accretion occurs predominantly along streams that originate from the cosmic web and consist of heated gas. Clusters that are unrelaxed in terms of their X-ray morphology are characterized by higher mass inflow rates and deeper penetration of the streams, typically into the inner third of the virial radius. The penetrating streams generate elevated random motions, bulk flows and cold fronts. The degree of penetration of the streams may change over time such that clusters can switch from being unrelaxed to relaxed over a time-scale of several giga years.

Mass, light and colour of the cosmic web in the supercluster SCL2243-0935 (z = 0.447)

NASA Astrophysics Data System (ADS)

Schirmer, M.; Hildebrandt, H.; Kuijken, K.; Erben, T.

2011-08-01

Aims: In archival 2.2 m MPG-ESO/WFI data we discovered several mass peaks through weak gravitational lensing, forming a possible supercluster at redshift 0.45. Through wide-field imaging and spectroscopy we aim to identify the supercluster centre, confirm individual member clusters, and detect possible connecting filaments. Methods: Through multi-colour imaging with CFHT/Megaprime and INT/WFC we identify a population of early-type galaxies and use it to trace the supercluster network. EMMI/NTT multi-object spectroscopy is used to verify the initial shear-selected cluster candidates. We use weak gravitational lensing to obtain mass estimates for the supercluster centre and the filaments. Results: We identified the centre of the SCL2243-0935 supercluster, MACS J2243-0935, which was found independently by Ebeling et al. (2001, 2010). We found 13 more clusters or overdensities embedded in a large filamentary network. Spectroscopic confirmation for about half of them is still pending. Three (5{-15) h70-1} Mpc filaments are detected, and we estimate the global size of SCL2243 to be 45×15×50 h70-1 Mpc, making it one of the largest superclusters known at intermediate redshifts. Weak lensing yields r200=(2.06±0.13) h_{70-1} Mpc and M200 = (1.54 ± 0.29) × 1015 M⊙ for MACS J2243 with M/L = 428 ± 82, very similar to results from size-richness cluster scaling relations. Integrating the weak lensing surface mass density over the supercluster network (defined by increased i-band luminosity or g - i colours), we find (1.53 ± 1.01) × 1015 M⊙ and M/L = 305 ± 201 for the three main filaments, consistant with theoretical predictions. The filaments' projected dimensionless surface mass density κ varies between 0.007 - 0.012, corresponding to ρ/ρcrit = 10 - 100 depending on location and de-projection. The greatly varying density of the cosmic web is also reflected in the mean colour of galaxies, e.g. ⟨ g - i ⟩ = 2.27 mag for the supercluster centre and 1.80 mag for the filaments. Conclusions: SCL2243 is significantly larger and much more richly structured than other known superclusters such as A901/902 or MS0302 studied with weak lensing before. It is a text-book supercluster with little contamination along the line of sight, making it a perfect sandbox for testing new techniques probing the cosmic web. This work is based on observations obtained with MegaPrime/MegaCam, a joint project of CFHT and CEA/DAPNIA, at the Canada-France-Hawaii Telescope (CFHT) which is operated by the National Research Council (NRC) of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the University of Hawaii (programme ID: 2008BO01); based on observations made with ESO Telescopes at the La Silla and Paranal Observatories, Chile (ESO Programmes 165.S-0187 and 079.A-0063); based on observations made with the 2.5 m Isaac Newton Telescope operated on the island of La Palma by the Isaac Newton Group in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias (programme ID 2008B/C11 and 2009B/C1).Appendices are available in electronic form at http://www.aanda.org

Towards early software reliability prediction for computer forensic tools (case study).

PubMed

Abu Talib, Manar

2016-01-01

Versatility, flexibility and robustness are essential requirements for software forensic tools. Researchers and practitioners need to put more effort into assessing this type of tool. A Markov model is a robust means for analyzing and anticipating the functioning of an advanced component based system. It is used, for instance, to analyze the reliability of the state machines of real time reactive systems. This research extends the architecture-based software reliability prediction model for computer forensic tools, which is based on Markov chains and COSMIC-FFP. Basically, every part of the computer forensic tool is linked to a discrete time Markov chain. If this can be done, then a probabilistic analysis by Markov chains can be performed to analyze the reliability of the components and of the whole tool. The purposes of the proposed reliability assessment method are to evaluate the tool's reliability in the early phases of its development, to improve the reliability assessment process for large computer forensic tools over time, and to compare alternative tool designs. The reliability analysis can assist designers in choosing the most reliable topology for the components, which can maximize the reliability of the tool and meet the expected reliability level specified by the end-user. The approach of assessing component-based tool reliability in the COSMIC-FFP context is illustrated with the Forensic Toolkit Imager case study.

Self-shielding of hydrogen in the IGM during the epoch of reionization

NASA Astrophysics Data System (ADS)

Chardin, Jonathan; Kulkarni, Girish; Haehnelt, Martin G.

2018-04-01

We investigate self-shielding of intergalactic hydrogen against ionizing radiation in radiative transfer simulations of cosmic reionization carefully calibrated with Lyα forest data. While self-shielded regions manifest as Lyman-limit systems in the post-reionization Universe, here we focus on their evolution during reionization (redshifts z = 6-10). At these redshifts, the spatial distribution of hydrogen-ionizing radiation is highly inhomogeneous, and some regions of the Universe are still neutral. After masking the neutral regions and ionizing sources in the simulation, we find that the hydrogen photoionization rate depends on the local hydrogen density in a manner very similar to that in the post-reionization Universe. The characteristic physical hydrogen density above which self-shielding becomes important at these redshifts is about nH ˜ 3 × 10-3 cm-3, or ˜20 times the mean hydrogen density, reflecting the fact that during reionization photoionization rates are typically low enough that the filaments in the cosmic web are often self-shielded. The value of the typical self-shielding density decreases by a factor of 3 between redshifts z = 3 and 10, and follows the evolution of the average photoionization rate in ionized regions in a simple fashion. We provide a simple parameterization of the photoionization rate as a function of density in self-shielded regions during the epoch of reionization.

Self-shielding of hydrogen in the IGM during the epoch of reionization

NASA Astrophysics Data System (ADS)

Chardin, Jonathan; Kulkarni, Girish; Haehnelt, Martin G.

2018-07-01

We investigate self-shielding of intergalactic hydrogen against ionizing radiation in radiative transfer simulations of cosmic reionization carefully calibrated with Lyα forest data. While self-shielded regions manifest as Lyman limit systems in the post-reionization Universe, here we focus on their evolution during reionization (redshifts z = 6-10). At these redshifts, the spatial distribution of hydrogen-ionizing radiation is highly inhomogeneous, and some regions of the Universe are still neutral. After masking the neutral regions and ionizing sources in the simulation, we find that the hydrogen photoionization rate depends on the local hydrogen density in a manner very similar to that in the post-reionization Universe. The characteristic physical hydrogen density above which self-shielding becomes important at these redshifts is about nH ˜ 3 × 10-3 cm-3, or ˜20 times the mean hydrogen density, reflecting the fact that during reionization photoionization rates are typically low enough that the filaments in the cosmic web are often self-shielded. The value of the typical self-shielding density decreases by a factor of 3 between redshifts z = 3 and 10, and follows the evolution of the average photoionization rate in ionized regions in a simple fashion. We provide a simple parametrization of the photoionization rate as a function of density in self-shielded regions during the epoch of reionization.

Variations of cosmic large-scale structure covariance matrices across parameter space

NASA Astrophysics Data System (ADS)

Reischke, Robert; Kiessling, Alina; Schäfer, Björn Malte

2017-03-01

The likelihood function for cosmological parameters, given by e.g. weak lensing shear measurements, depends on contributions to the covariance induced by the non-linear evolution of the cosmic web. As highly non-linear clustering to date has only been described by numerical N-body simulations in a reliable and sufficiently precise way, the necessary computational costs for estimating those covariances at different points in parameter space are tremendous. In this work, we describe the change of the matter covariance and the weak lensing covariance matrix as a function of cosmological parameters by constructing a suitable basis, where we model the contribution to the covariance from non-linear structure formation using Eulerian perturbation theory at third order. We show that our formalism is capable of dealing with large matrices and reproduces expected degeneracies and scaling with cosmological parameters in a reliable way. Comparing our analytical results to numerical simulations, we find that the method describes the variation of the covariance matrix found in the SUNGLASS weak lensing simulation pipeline within the errors at one-loop and tree-level for the spectrum and the trispectrum, respectively, for multipoles up to ℓ ≤ 1300. We show that it is possible to optimize the sampling of parameter space where numerical simulations should be carried out by minimizing interpolation errors and propose a corresponding method to distribute points in parameter space in an economical way.

Experience of Application of Silicon Matrix as a Charge Detector in the ATIC Experiment

NASA Technical Reports Server (NTRS)

Zatsepin, V. I.; Adams, J. H.; Christl, M. J.

2003-01-01

The Advanced Thin Ionization Calorimeter (ATIC) was built for series of long-duration balloon flights in Antarctica. Its main goal is to measure energy spectra of cosmic ray nuclei from protons up to iron nuclei in the wide range of their energy from 30 GeV up to 100 TeV. The ATIC balloon experiment had its first, test flight that lasted for 16 days from 28 Dec 2000 to 13 Jan 2001 around the South Pole. The ATIC spectrometer consists of a fully active BGO calorimeter, scintillator hodoscopes and a silicon matrix. The silicon matrix consisted of 4480 pixels was used as a charge detector in the experiment. About 25 million cosmic ray events were detected during the flight. In the paper, the charge spectrum obtained with the silicon matrix is analyzed.

Comparison of distributed reacceleration and leaky-box models of cosmic-ray abundances (Z = 3-28)

NASA Technical Reports Server (NTRS)

Letaw, John R.; Silberberg, Rein; Tsao, C. H.

1993-01-01

A large collection of elemental and isotopic cosmic-ray data has been analyzed using the leaky-box transport model with and without reacceleration in the interstellar medium. Abundances of isotopes and elements with charges Z = 3-28 and energies E = 10 MeV/nucleon-1 TeV/nucleon were explored. Our results demonstrate that reacceleration models make detailed and accurate predictions with the same number of parameters or fewer as standard leaky-box models. Ad hoc fitting parameters in the standard model are replaced by astrophysically significant reacceleration parameters. Distributed reacceleration models explain the peak in secondary-to-primary ratios around 1 GeV/nucleon. They diminish the discrepancy between rigidity-dependent leakage and energy-independent anisotropy. They also offer the possibility of understanding isotopic anomalies at low energy.

Studying Solar Wind Properties Around CIRs and Their Effects on GCR Modulation

NASA Astrophysics Data System (ADS)

Ghanbari, K.; Florinski, V. A.

2017-12-01

Corotating interaction region (CIR) events occur when a fast solar wind stream overtakes slow solar wind, forming a compression region ahead and a rarefaction region behind in the fast solar wind. Usually this phenomena occurs along with a crossing of heliospheric current sheet which is the surface separating solar magnetic fields of opposing polarities. In this work, the solar plasma data provided by the ACE science center are utilized to do a superposed epoch analysis on solar parameters including proton density, proton temperature, solar wind speed and solar magnetic field in order to study how the variations of these parameters affect the modulation of galactic cosmic rays. Magnetic fluctuation variances in different parts a of CIR are computed and analyzed using similar techniques in order to understand the cosmic-ray diffusive transport in these regions.

Limits of Gaussian fluctuations in the cosmic microwave background at 19.2 GHz

NASA Technical Reports Server (NTRS)

Boughn, S. P.; Cheng, E. S.; Cottingham, D. A.; Fixsen, D. J.

1992-01-01

The Northern Hemisphere data from the 19.2 GHz full sky survey are analyzed to place limits on the magnitude of Gaussian fluctuations in the cosmic microwave background implied by a variety of correlation functions. Included among the models tested are the monochromatic and Gaussian-shaped families, and those with power-law spectra for n values between -2 and 1. An upper bound is placed on the quadrupole anisotropy of Delta T/T less than 3.2 x 10 exp -5 rms, and an upper bound on scale-invariant (n = 1) fluctuations of a2 less than 4.5 x 10 exp -5 (95 percent confidence level). There is significant contamination of these data from Galactic emission, and improvement of the modeling of the Galaxy could yield a significant reduction of these upper bounds.

Limits on Gaussian fluctuations in the cosmic microwave background at 19.2 GHz

NASA Technical Reports Server (NTRS)

Boughn, S. P.; Cheng, E. S.; Cottingham, D. A.; Fixsen, D. J.

1991-01-01

The Northern Hemisphere data from the 19.2 GHz full sky survey are analyzed to place limits on the magnitude of Gaussian fluctuations in the cosmic microwave background implied by a variety of correlation functions. Included among the models tested are the monochromatic and Gaussian-shaped families, and those with power law spectra for n from -2 to 1. We place an upper bound on the quadrupole anisotropy of DeltaT/T less than 3.2 x 10 exp -5 rms, and an upper bound on scale-invariant (n = 1) fluctuations of a2 less than 4.5 x 10 exp -5 (95 percent confidence level). There is significant contamination of these data from Galactic emission, and improvement of our modeling of the Galaxy could yield a significant reduction of these upper bounds.

Chemical abundances of cosmic rays greater than 4.5 GV measured with a large area proportional counter-scintillation counter stack

NASA Technical Reports Server (NTRS)

Lheureux, J.; Fan, C. Y.; Mainardi, R.; Gloeckler, G.

1974-01-01

A 6500 sq cm-ster cosmic-ray detector consisting of 12 gas counter trays sandwiched between two large-area circular scintillation counters was flown from Palestine, Texas in November 1972 to study the composition of primary particles greater than 1.5 GeV/nucleon in the charge range from 3 to 30. For each analyzed event, the particle trajectory was recorded, using four 20-wire proportional counter trays. Also recorded were the energy loss in each of the solid counters and the dE/dx losses in each of the 12 gas counters. The large dynamic range of the detector is established by operating six of the gas counters in the ionization mode. A description of the instrument and some preliminary results are given.

Chemical abundances of cosmic rays greater than 4.5 GV measured with a large area proportional counter-scintillation counter stack

NASA Technical Reports Server (NTRS)

Lheureux, J.; Fan, C. Y.; Gloeckler, G.; Mainardi, R.

1973-01-01

A 6500 sq cm-ster cosmic ray detector consisting of twelve gas counter trays sandwiched between two large area circular scintillation counters was flown from Palestine, Texas in November of 1972 to study the composition of primary particles 1.5 GeV/nucleon in the charge range 3 to 30. For each analyzed event, a recording was made of (1) the particle trajectory using four 20 wire proportional counter trays, (2) the energy loss in each of the solid counters, and (3) the dE/dx losses in each of the twelve gas counters. The large dynamic range of the detector is established by operating six of the gas counters in the ionization mode. A description of the instrument and some preliminary results are given.

Analyzing the User Behavior toward Electronic Commerce Stimuli

PubMed Central

Lorenzo-Romero, Carlota; Alarcón-del-Amo, María-del-Carmen; Gómez-Borja, Miguel-Ángel

2016-01-01

Based on the Stimulus-Organism-Response paradigm this research analyzes the main differences between the effects of two types of web technologies: Verbal web technology (i.e., navigational structure as utilitarian stimulus) versus non-verbal web technology (music and presentation of products as hedonic stimuli). Specific webmosphere stimuli have not been examined yet as separate variables and their impact on internal and behavioral responses seems unknown. Therefore, the objective of this research consists in analyzing the impact of these web technologies –which constitute the web atmosphere or webmosphere of a website– on shopping human behavior (i.e., users’ internal states -affective, cognitive, and satisfaction- and behavioral responses – approach responses, and real shopping outcomes-) within the retail online store created by computer, taking into account some mediator variables (i.e., involvement, atmospheric responsiveness, and perceived risk). A 2 (“free” versus “hierarchical” navigational structure) × 2 (“on” versus “off” music) × 2 (“moving” versus “static” images) between-subjects computer experimental design is used to test empirically this research. In addition, an integrated methodology was developed allowing the simulation, tracking and recording of virtual user behavior within an online shopping environment. As main conclusion, this study suggests that the positive responses of online consumers might increase when they are allowed to freely navigate the online stores and their experience is enriched by animate gifts and music background. The effect caused by mediator variables modifies relatively the final shopping human behavior. PMID:27965549

Should indications for WEB aneurysm treatment be enlarged? Report of a series of 20 patients with aneurysms in "atypical" locations for WEB treatment.

PubMed

Pierot, L; Biondi, A; Narata, A-P; Mihalea, C; Januel, A-C; Metaxas, G; Bibi, R; Caroff, J; Soize, S; Cognard, C; Spelle, L; Herbreteau, D

2017-06-01

Flow disruption with the WEB device is an innovative technique for the endovascular treatment of wide neck bifurcation aneurysms. Good clinical practice trials have shown high safety of this treatment with good efficacy. Technical developments (single layer devices and smaller microcatheters) facilitate the treatment, potentially leading to enlargement of indications. This series is collecting aneurysms in "atypical" locations for WEB treatment and analyzing safety and efficacy of this treatment. In each participating center, patients with aneurysms treated with WEB were prospectively included in a local database. Patients treated for aneurysms in "atypical" locations were extracted. Patient and aneurysm characteristics, intraoperative complications, and anatomical results at the end of the procedure and at last follow-up were collected and analyzed. Five French neurointerventional centers included 20 patients with 20 aneurysms in "atypical" locations for WEB treatment treated with WEB. Aneurysm locations were ICA carotid-ophthalmic in 9 aneurysms (45.0%), ICA posterior communicating in 4 (20.0%), Pericallosal artery in 5 (25.0%), and basilar artery between P1 and superior cerebellar artery in 2 (10.0%). There were no complications (thromboembolic or intraoperative rupture) in this series. At follow-up (mean: 7.4 months), adequate occlusion was obtained in 100.0% of aneurysms. This series confirms that it is possible to enlarge indications of WEB treatment to "atypical" locations with good safety and efficacy. These data have to be confirmed in large prospective series. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Constraints on the gamma-ray emission from the cluster-scale AGN outburst in the Hydra A galaxy cluster

NASA Astrophysics Data System (ADS)

HESS Collaboration; Abramowski, A.; Acero, F.; Aharonian, F.; Akhperjanian, A. G.; Anton, G.; Balenderan, S.; Balzer, A.; Barnacka, A.; Becherini, Y.; Becker, J.; Bernlöhr, K.; Birsin, E.; Biteau, J.; Bochow, A.; Boisson, C.; Bolmont, J.; Bordas, P.; Brucker, J.; Brun, F.; Brun, P.; Bulik, T.; Büsching, I.; Carrigan, S.; Casanova, S.; Cerruti, M.; Chadwick, P. M.; Charbonnier, A.; Chaves, R. C. G.; Cheesebrough, A.; Cologna, G.; Conrad, J.; Couturier, C.; Daniel, M. K.; Davids, I. D.; Degrange, B.; Deil, C.; Dickinson, H. J.; Djannati-Ataï, A.; Domainko, W.; O'C. Drury, L.; Dubus, G.; Dutson, K.; Dyks, J.; Dyrda, M.; Egberts, K.; Eger, P.; Espigat, P.; Fallon, L.; Fegan, S.; Feinstein, F.; Fernandes, M. V.; Fiasson, A.; Fontaine, G.; Förster, A.; Füßling, M.; Gajdus, M.; Gallant, Y. A.; Garrigoux, T.; Gast, H.; Gérard, L.; Giebels, B.; Glicenstein, J. F.; Glück, B.; Göring, D.; Grondin, M.-H.; Häffner, S.; Hague, J. D.; Hahn, J.; Hampf, D.; Harris, J.; Hauser, M.; Heinz, S.; Heinzelmann, G.; Henri, G.; Hermann, G.; Hillert, A.; Hinton, J. A.; Hofmann, W.; Hofverberg, P.; Holler, M.; Horns, D.; Jacholkowska, A.; Jahn, C.; Jamrozy, M.; Jung, I.; Kastendieck, M. A.; Katarzyński, K.; Katz, U.; Kaufmann, S.; Khélifi, B.; Klochkov, D.; Kluźniak, W.; Kneiske, T.; Komin, Nu.; Kosack, K.; Kossakowski, R.; Krayzel, F.; Laffon, H.; Lamanna, G.; Lenain, J.-P.; Lennarz, D.; Lohse, T.; Lopatin, A.; Lu, C.-C.; Marandon, V.; Marcowith, A.; Masbou, J.; Maurin, G.; Maxted, N.; Mayer, M.; McComb, T. J. L.; Medina, M. C.; Méhault, J.; Moderski, R.; Mohamed, M.; Moulin, E.; Naumann, C. L.; Naumann-Godo, M.; de Naurois, M.; Nedbal, D.; Nekrassov, D.; Nguyen, N.; Nicholas, B.; Niemiec, J.; Nolan, S. J.; Ohm, S.; de Oña Wilhelmi, E.; Opitz, B.; Ostrowski, M.; Oya, I.; Panter, M.; Paz Arribas, M.; Pekeur, N. W.; Pelletier, G.; Perez, J.; Petrucci, P.-O.; Peyaud, B.; Pita, S.; Pühlhofer, G.; Punch, M.; Quirrenbach, A.; Raue, M.; Reimer, A.; Reimer, O.; Renaud, M.; de los Reyes, R.; Rieger, F.; Ripken, J.; Rob, L.; Rosier-Lees, S.; Rowell, G.; Rudak, B.; Rulten, C. B.; Sahakian, V.; Sanchez, D. A.; Santangelo, A.; Schlickeiser, R.; Schulz, A.; Schwanke, U.; Schwarzburg, S.; Schwemmer, S.; Sheidaei, F.; Skilton, J. L.; Sol, H.; Spengler, G.; Stawarz, Ł.; Steenkamp, R.; Stegmann, C.; Stinzing, F.; Stycz, K.; Sushch, I.; Szostek, A.; Tavernet, J.-P.; Terrier, R.; Tluczykont, M.; Valerius, K.; van Eldik, C.; Vasileiadis, G.; Venter, C.; Viana, A.; Vincent, P.; Völk, H. J.; Volpe, F.; Vorobiov, S.; Vorster, M.; Wagner, S. J.; Ward, M.; White, R.; Wierzcholska, A.; Zacharias, M.; Zajczyk, A.; Zdziarski, A. A.; Zech, A.; Zechlin, H.-S.; Ali, M. O.

2012-09-01

Context. In some galaxy clusters, powerful active galactic nuclei (AGN) have blown bubbles with cluster scale extent into the ambient medium. The main pressure support of these bubbles is not known to date, but cosmic rays are a viable possibility. For such a scenario copious gamma-ray emission is expected as a tracer of cosmic rays from these systems. Aims: Hydra A, the closest galaxy cluster hosting a cluster scale AGN outburst, located at a redshift of 0.0538, is investigated for being a gamma-ray emitter with the High Energy Stereoscopic System (H.E.S.S.) array and the Fermi Large Area Telescope (Fermi-LAT). Methods: Data obtained in 20.2 h of dedicated H.E.S.S. observations and 38 months of Fermi-LAT data, gathered by its usual all-sky scanning mode, have been analyzed to search for a gamma-ray signal. Results: No signal has been found in either data set. Upper limits on the gamma-ray flux are derived and are compared to models. These are the first limits on gamma-ray emission ever presented for galaxy clusters hosting cluster scale AGN outbursts. Conclusions: The non-detection of Hydra A in gamma-rays has important implications on the particle populations and physical conditions inside the bubbles in this system. For the case of bubbles mainly supported by hadronic cosmic rays, the most favorable scenario, which involves full mixing between cosmic rays and embedding medium, can be excluded. However, hadronic cosmic rays still remain a viable pressure support agent to sustain the bubbles against the thermal pressure of the ambient medium. The largest population of highly-energetic electrons, which are relevant for inverse-Compton gamma-ray production is found in the youngest inner lobes of Hydra A. The limit on the inverse-Compton gamma-ray flux excludes a magnetic field below half of the equipartition value of 16 μG in the inner lobes.

Breaking and Fixing Origin-Based Access Control in Hybrid Web/Mobile Application Frameworks.

PubMed

Georgiev, Martin; Jana, Suman; Shmatikov, Vitaly

2014-02-01

Hybrid mobile applications (apps) combine the features of Web applications and "native" mobile apps. Like Web applications, they are implemented in portable, platform-independent languages such as HTML and JavaScript. Like native apps, they have direct access to local device resources-file system, location, camera, contacts, etc. Hybrid apps are typically developed using hybrid application frameworks such as PhoneGap. The purpose of the framework is twofold. First, it provides an embedded Web browser (for example, WebView on Android) that executes the app's Web code. Second, it supplies "bridges" that allow Web code to escape the browser and access local resources on the device. We analyze the software stack created by hybrid frameworks and demonstrate that it does not properly compose the access-control policies governing Web code and local code, respectively. Web code is governed by the same origin policy, whereas local code is governed by the access-control policy of the operating system (for example, user-granted permissions in Android). The bridges added by the framework to the browser have the same local access rights as the entire application, but are not correctly protected by the same origin policy. This opens the door to fracking attacks, which allow foreign-origin Web content included into a hybrid app (e.g., ads confined in iframes) to drill through the layers and directly access device resources. Fracking vulnerabilities are generic: they affect all hybrid frameworks, all embedded Web browsers, all bridge mechanisms, and all platforms on which these frameworks are deployed. We study the prevalence of fracking vulnerabilities in free Android apps based on the PhoneGap framework. Each vulnerability exposes sensitive local resources-the ability to read and write contacts list, local files, etc.-to dozens of potentially malicious Web domains. We also analyze the defenses deployed by hybrid frameworks to prevent resource access by foreign-origin Web content and explain why they are ineffectual. We then present NoFrak, a capability-based defense against fracking attacks. NoFrak is platform-independent, compatible with any framework and embedded browser, requires no changes to the code of the existing hybrid apps, and does not break their advertising-supported business model.

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

IsoWeb: A Bayesian Isotope Mixing Model for Diet Analysis of the Whole Food Web

PubMed Central

Kadoya, Taku; Osada, Yutaka; Takimoto, Gaku

2012-01-01

Quantitative description of food webs provides fundamental information for the understanding of population, community, and ecosystem dynamics. Recently, stable isotope mixing models have been widely used to quantify dietary proportions of different food resources to a focal consumer. Here we propose a novel mixing model (IsoWeb) that estimates diet proportions of all consumers in a food web based on stable isotope information. IsoWeb requires a topological description of a food web, and stable isotope signatures of all consumers and resources in the web. A merit of IsoWeb is that it takes into account variation in trophic enrichment factors among different consumer-resource links. Sensitivity analysis using realistic hypothetical food webs suggests that IsoWeb is applicable to a wide variety of food webs differing in the number of species, connectance, sample size, and data variability. Sensitivity analysis based on real topological webs showed that IsoWeb can allow for a certain level of topological uncertainty in target food webs, including erroneously assuming false links, omission of existent links and species, and trophic aggregation into trophospecies. Moreover, using an illustrative application to a real food web, we demonstrated that IsoWeb can compare the plausibility of different candidate topologies for a focal web. These results suggest that IsoWeb provides a powerful tool to analyze food-web structure from stable isotope data. We provide R and BUGS codes to aid efficient applications of IsoWeb. PMID:22848427

Calculation of cosmic ray induced single event upsets: Program CRUP (Cosmic Ray Upset Program)

NASA Astrophysics Data System (ADS)

Shapiro, P.

1983-09-01

This report documents PROGRAM CRUP, COSMIC RAY UPSET PROGRAM. The computer program calculates cosmic ray induced single-event error rates in microelectronic circuits exposed to several representative cosmic-ray environments.

Analysis of powerful heliospheric non-geoeffective event of the 28 April, 2015 in muon flux

NASA Astrophysics Data System (ADS)

Astapov, I. I.; Barbashina, N. S.; Veselovsky, I. S.; Osetrova, N. V.; Petrukhin, A. A.; Shutenko, V. V.

2016-02-01

The coronal mass ejection (CME) that occurred on April 28, 2015 is analyzed. The passage of the ejection did not cause geoeffective disturbances in the near-Earth space. At the same time, the CME had a significant impact on the flux of cosmic rays registered on the Earth's surface by the muon hodoscope URAGAN.