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Sample records for cosmic domain effective

  1. Terrestrial effects of high energy cosmic rays

    NASA Astrophysics Data System (ADS)

    Atri, Dimitra

    On geological timescales, the Earth is likely to be exposed to higher than the usual flux of high energy cosmic rays (HECRs) from astrophysical sources such as nearby supernovae, gamma ray bursts or by galactic shocks. These high-energy particles strike the Earth's atmosphere, initiating an extensive air shower. As the air shower propagates deeper, it ionizes the atmosphere by producing charged secondary particles and photons. Increased ionization leads to changes in atmospheric chemistry, resulting in ozone depletion. This increases the flux of solar UVB radiation at the surface, which is potentially harmful to living organisms. Increased ionization affects the global electrical circuit, which could enhance the low-altitude cloud formation rate. Secondary particles such as muons and thermal neutrons produced as a result of hadronic interactions of the primary cosmic rays with the atmosphere are able to reach the ground, enhancing the biological radiation dose. The muon flux dominates the radiation dose from cosmic rays causing damage to DNA and an increase in mutation rates and cancer, which can have serious biological implications for surface and sub-surface life. Using CORSIKA, we perform massive computer simulations and construct lookup tables for 10 GeV - 1 PeV primaries, which can be used to quantify these effects from enhanced cosmic ray exposure to any astrophysical source. These tables are freely available to the community and can be used for other studies. We use these tables to study the terrestrial implications of galactic shock generated by the infall of our galaxy toward the Virgo cluster. Increased radiation dose from muons could be a possible mechanism explaining the observed periodicity in biodiversity in paleobiology databases.

  2. Plasma effects on extragalactic ultra-high-energy cosmic ray hadron beams in cosmic voids

    SciTech Connect

    Krakau, S.; Schlickeiser, R. E-mail: rsch@tp4.rub.de

    2014-07-01

    The linear instability of an ultrarelativistic hadron beam (Γ {sub b} ≈ 10{sup 6}) in the unmagnetized intergalactic medium (IGM) is investigated with respect to the excitation of collective electrostatic and aperiodic electromagnetic fluctuations. This analysis is important for the propagation of extragalactic ultrarelativistic cosmic rays (E > 10{sup 15} eV) from their distant sources to Earth. We calculate minimum instability growth times that are orders of magnitude shorter than the cosmic ray propagation time in the IGM. Due to nonlinear effects, especially the modulation instability, the cosmic ray beam stabilizes and can propagate with nearly no energy loss through the IGM.

  3. Effect of cosmic ray on global high cloud from MODIS

    NASA Astrophysics Data System (ADS)

    Kim, H.-S.; Choi, Y.-S.

    2012-04-01

    than low and middle clouds. Considering the correlations with dependence on regions, a physical cloud process regarding to cosmic ray may not be universal perhaps due to anonymous factors affecting the cloud amount. However, our synthetic conclusion is that the amount of global high cloud increases with increased cosmic ray. This implies that infrared warming effect due to increased high cloud may be intensified when more cosmic ray comes in.

  4. Effects of solar magnetic field on cosmic rays

    NASA Technical Reports Server (NTRS)

    Goncher, G. A.; Kolomeets, E. V.; Lyakhova, A. K.; Slyunyaeva, N. V.; Stekolnikov, N. V.

    1985-01-01

    Aspects of the problem of galactic cosmic ray propagation, including inversion of the solar total magnetic field and an analysis of data related to the heliomagnetic cycle are discussed. It is noted that the global structure of the solar magnetic field results in an additional flux of galactic cosmic rays generated by curvature and gradient drifts. An analysis of heliomagnetic cycle data shows that the latitudinal gradient results in a N-S asymmetry, with the amplitude of the effect growing with depth in the atmosphere. The inversion of the solar total magnetic field, drift effects, and other space distributions are found to contribute to a 22-year cycle of solar activity.

  5. 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.

  6. The origins of cosmic rays and quantum effects on gravity

    NASA Technical Reports Server (NTRS)

    Tomozawa, Y.

    1985-01-01

    The energy spectrum of primary cosmic rays is explained by particles emitted during a thermal expansion of explosive objects inside and near the galaxy, remnants of which may be supernova and/or active talaxies, or even stars or galaxies that disappeared from our sight after the explosion. A power law energy spectrum for cosmic rays, E to the (-alpha -1, is obtained from an expansion rate T is proportional to R to the alpha. Using the solution of the Einstein equation, we obtain a spectrum which agrees very well with experimental data. The implication of an inflationary early universe on the cosmic ray spectrum is also discussed. It is also suggested that the conflict between this model and the singularity theorem in classical general relativity may be eliminated by quantum effects.

  7. The Ground Temperature Effect on Cosmic-Ray Muons at Mid latitude City

    NASA Astrophysics Data System (ADS)

    Maghrabi, A.; Alotaibi, R.; Almutayri, M.; Garawi, M.; Baig, M.

    2015-08-01

    The investigation of meteorological effects is of a great importance to the analysis of the cosmic ray variations. In this paper, we study the effect of the ground temperature on the cosmic ray recorded by KACST detector. This detector has monitored secondary cosmic ray muon since 2002 at Riyadh, Saudi Arabia; (lat 24 43; long. 46 40; alt. 613 m; Rc ∼14 GV).

  8. Single particle effects, Biostack, and risk evaluation - Studies on the radiation risk from Galactic cosmic rays

    NASA Technical Reports Server (NTRS)

    Curtis, Stanley B.

    1993-01-01

    The possible health risks posed by Galactic cosmic rays, especially the possible heightened cancer risk, are examined. The results of the Biostack studies of the biological effects of high-energy cosmic rays are discussed. The biological mechanisms involved in possible harm due to cosmic rays are considered.

  9. Evaluation of Gnevyshev Gap Effects on Cosmic Ray Modulation

    NASA Astrophysics Data System (ADS)

    Storini, Marisa; Laurenza, M.; Fujii, Z.

    2003-07-01

    Data from three neutron monitors (Climax, Rome, Huancayo/Haleakala) and from the Nagoya multidirectional muon telescope are used to investigate the energy dependence of the Gnevyshev Gap effects on galactic particles during solar activity cycle N. 22. Results suggest that the dual-peak shape of the modulation of galactic cosmic rays should be practically negligible for rigidity particles above 150 ± 20 GV.

  10. Effect of Extra Dimensions on Gravitational Waves from Cosmic Strings

    SciTech Connect

    O'Callaghan, Eimear; Chadburn, Sarah; Geshnizjani, Ghazal; Gregory, Ruth; Zavala, Ivonne

    2010-08-20

    We show how the motion of cosmic superstrings in extra dimensions can modify the gravitational wave signal from cusps. Additional dimensions both round off cusps, as well as reducing the probability of their formation, and thus give a significant dimension dependent damping of the gravitational waves. We look at the implication of this effect for LIGO and LISA, as well as commenting on more general frequency bands.

  11. Cosmic bubble and domain wall instabilities II: fracturing of colliding walls

    SciTech Connect

    Braden, Jonathan; Bond, J. Richard; Mersini-Houghton, Laura

    2015-08-26

    We study collisions between nearly planar domain walls including the effects of small initial nonplanar fluctuations. These perturbations represent the small fluctuations that must exist in a quantum treatment of the problem. In a previous paper, we demonstrated that at the linear level a subset of these fluctuations experience parametric amplification as a result of their coupling to the planar symmetric background. Here we study the full three-dimensional nonlinear dynamics using lattice simulations, including both the early time regime when the fluctuations are well described by linear perturbation theory as well as the subsequent stage of fully nonlinear evolution. We find that the nonplanar fluctuations have a dramatic effect on the overall evolution of the system. Specifically, once these fluctuations begin to interact nonlinearly the split into a planar symmetric part of the field and the nonplanar fluctuations loses its utility. At this point the colliding domain walls dissolve, with the endpoint of this being the creation of a population of oscillons in the collision region. The original (nearly) planar symmetry has been completely destroyed at this point and an accurate study of the system requires the full three-dimensional simulation.

  12. Cosmic bubble and domain wall instabilities II: fracturing of colliding walls

    SciTech Connect

    Braden, Jonathan; Bond, J. Richard; Mersini-Houghton, Laura E-mail: bond@cita.utoronto.ca

    2015-08-01

    We study collisions between nearly planar domain walls including the effects of small initial nonplanar fluctuations. These perturbations represent the small fluctuations that must exist in a quantum treatment of the problem. In a previous paper, we demonstrated that at the linear level a subset of these fluctuations experience parametric amplification as a result of their coupling to the planar symmetric background. Here we study the full three-dimensional nonlinear dynamics using lattice simulations, including both the early time regime when the fluctuations are well described by linear perturbation theory as well as the subsequent stage of fully nonlinear evolution. We find that the nonplanar fluctuations have a dramatic effect on the overall evolution of the system. Specifically, once these fluctuations begin to interact nonlinearly the split into a planar symmetric part of the field and the nonplanar fluctuations loses its utility. At this point the colliding domain walls dissolve, with the endpoint of this being the creation of a population of oscillons in the collision region. The original (nearly) planar symmetry has been completely destroyed at this point and an accurate study of the system requires the full three-dimensional simulation.

  13. Topological Casimir effect in compactified cosmic string spacetime

    NASA Astrophysics Data System (ADS)

    Bezerra de Mello, E. R.; Saharian, A. A.

    2012-02-01

    We investigate the Wightman function, the vacuum expectation values of the field squared and the energy-momentum tensor for a massive scalar field with general curvature coupling in the generalized cosmic string geometry with a compact dimension along its axis. The boundary condition along the compactified dimension is taken in general form with an arbitrary phase. The vacuum expectation values are decomposed into two parts. The first one corresponds to the uncompactified cosmic string geometry and the second one is the correction induced by the compactification. The asymptotic behavior of the vacuum expectation values of the field squared, energy density and stresses is investigated near the string and at large distances. We show that the nontrivial topology due to the cosmic string enhances the vacuum polarization effects induced by the compactness of spatial dimension for both the field squared and the vacuum energy density. A simple formula is given for the part of the integrated topological Casimir energy induced by the planar angle deficit. The results are generalized for a charged scalar field in the presence of a constant gauge field. In this case, the vacuum expectation values are periodic functions of the component of the vector potential along the compact dimension.

  14. Observations of supernova remnants and molecular clouds from the mm to the gamma-ray domain: bridging low and high energy cosmic rays

    NASA Astrophysics Data System (ADS)

    Gabici, Stefano; Montmerle, Thierry

    2015-10-01

    New evidence that cosmic rays (hadronic component) are accelerated by supernova remnant shocks all the way from low energies to high energies, has come from recent works combining gamma-ray observations in the sub-GeV to TeV domain on the one hand, and in the submm-mm domain on the other hand. These observations concern the specific cases of supernova remnants interacting with molecular cloud complexes, that have long been suspected to be ideal laboratories to study in situ cosmic ray acceleration and diffusion. Indeed, enhanced gamma-ray emission from neutral pion decay, as well as enhanced ionization (both by at least one order of magnitude with respect to average galactic values) have been observed in several regions of massive star formation housing supernova remnants interacting with molecular cloud complexes. This paper summarizes the main physical and chemical processes at work, as well as recent observations, that further support the paradigm of cosmic ray acceleration by supernova remnants all the way from the MeV domain up to several tens of TeV, although much work remains to be done to understand cosmic ray penetration and diffusion inside and around molecular clouds, and reveal the actual spectrum of the accelerated cosmic rays.

  15. On the effect of cosmic rays in bolometric cosmic microwave background measurements from the stratosphere

    NASA Astrophysics Data System (ADS)

    Masi, S.; Battistelli, E.; de Bernardis, P.; Lamagna, L.; Nati, F.; Nati, L.; Natoli, P.; Polenta, G.; Schillaci, A.

    2010-09-01

    Context. Precision measurements of the anisotropy of the cosmic microwave background (CMB) are able to detect low-level non-Gaussian features caused by either topological defects or the inflation process. These measurements are becoming feasable with the development of large arrays of ultra-sensitive bolometric detectors and their use in balloon-borne or satellite missions. However, the space environment includes a population of cosmic rays (CRs), which produce spurious spikes in bolometric signals. Aims: We analyze the effect of CRs on the measurement of CMB anisotropy maps and the estimate of cosmological non-Gaussianity and angular power spectra of the CMB. Methods: Using accurate simulations of noise and CR events in bolometric detectors, and de-spiking techniques, we produce simulated measured maps and analyze the Gaussianity and power spectrum of the maps for different levels and rates of CR events. Results: We find that a de-spiking technique based on outlier removal in the detector signals contributing to the same sky pixel is effective in removing CR events larger than the noise. However, low level events hidden in the noise produce a positive shift of the average power signal measured by a bolometer, and increase its variance. If the number of hits per pixel is large enough, the data distribution for each sky pixel is approximately Gaussian, but the skewness and the kurtosis of the temperatures of the pixels indicate the presence of some low-level non-Gaussianity. The standard noise estimation pipeline produces a positive bias in the power spectrum at high multipoles. Conclusions: In the case of a typical balloon-borne survey, the CR-induced non-Gaussianity will be marginally detectable in the membrane bolometer channels, but be negligible in the spider-web bolometer channels. In experiments with detector sensitivity better than 100 μK/√{Hz}, in an environment less favorable than the earth stratosphere, the CR-induced non-Gaussianity is likely to

  16. Modelling Cosmic-Ray Effects in the Protosolar Disk

    NASA Technical Reports Server (NTRS)

    Wilson, Thomas L.

    2010-01-01

    The role that Galactic cosmic rays (GCRs) and solar energetic particles (SEPs) play in the dynamic evolution of protosolar disks and the origin of our Solar System is a fundamental one. The GCRs are an important component of the interstellar medium (ISM), and even play a role in correcting the age determinations of some irons versus CAIs (calcium-aluminum inclusions) in meteoroids . Because CRs also are one of the energy transport mechanisms in a planetary nebula, the question of modelling their effect upon this broad subject is a serious topic for planetary science. The problem is addressed here.

  17. Brane Inflation: From Superstring to Cosmic Strings

    SciTech Connect

    Tye, S.-H. Henry

    2004-12-10

    Brane inflation, where branes move towards each other in the brane world, has been shown to be quite natural in superstring theory. Inflation ends when branes collide and heat the universe, initiating the hot big bang. Cosmic strings (but not domain walls or monopoles) are copiously produced during the brane collision. Using the COBE data on the temperature anisotropy in the cosmic microwave background, the cosmic string tension {mu} is estimated to be around 10 -6 > G{mu} > 10-11, while the present observational bound is 7 x 10 -7 > G{mu}. This implies that the anisotropy that seeds structure formation comes mostly from inflation, but with a small component (< 10%) from cosmic string effects. This cosmic string effect should be testable in the near future via gravitational lensing, the cosmic microwave background radiation, and/or gravitational wave detectors like LIGO II/VIRGO.

  18. The solar wind effect on cosmic rays and solar activity

    NASA Technical Reports Server (NTRS)

    Fujimoto, K.; Kojima, H.; Murakami, K.

    1985-01-01

    The relation of cosmic ray intensity to solar wind velocity is investigated, using neutron monitor data from Kiel and Deep River. The analysis shows that the regression coefficient of the average intensity for a time interval to the corresponding average velocity is negative and that the absolute effect increases monotonously with the interval of averaging, tau, that is, from -0.5% per 100km/s for tau = 1 day to -1.1% per 100km/s for tau = 27 days. For tau 27 days the coefficient becomes almost constant independently of the value of tau. The analysis also shows that this tau-dependence of the regression coefficiently is varying with the solar activity.

  19. Density tomography using cosmic ray muons: feasibility domain and field applications

    NASA Astrophysics Data System (ADS)

    Lesparre, N.; Gibert, D.; Marteau, J.; Déclais, Y.; Carbone, D.; Galichet, E.

    2010-12-01

    Muons are continuously produced when the protons forming the primary cosmic rays decay during their interactions with the molecules of the upper atmosphere. Both their short cross-section and their long life-time make the muons able to cross hectometers and even kilometers of rock before disintegrating. The flux of muons crossing a geological volume strongly depends on the quantity of matter encountered along their trajectories and, depending on both its size and its density, the geological object appears more or less opaque to muons. By measuring the muon flux emerging from the studied object and correcting for its geometry, the density structure can be deduced. The primary information obtained is the density averaged along muons trajectories and, to recover the 3D density distribution. The detector has to be moved around the target to acquire multi-angle images of the density structure. The inverse problem to be solved shares common features with seismic travel-time tomography and X-ray medical scans, but it also has specificities like Poissonian statistics, low signal-to-noise ratio and scattering which are discussed. Muon telescopes have been designed to sustain installations in harsh conditions such as might be encountered on volcanoes. Data acquired in open sky at various latitude and altitude allow to adjust the incoming muon flux model and to observe its temporal variations. The muon interactions with matter and the underground flux are constrained with data sets acquired inside the underground laboratory of the Mont Terri. The data analysis and the telescope model development are detailed. A model of the muon flux across a volcano is confronted to first measurements on La Soufrière de Guadeloupe volcano. The model takes into account a priori informations and solving kernels are computed to deduce the spatial resolution in order to define the elements size of the model heterogeneities. The spatio-temporal resolution of the method is in relation with the

  20. An Educational Study of the Barometric Effect of Cosmic Rays with a Geiger Counter

    ERIC Educational Resources Information Center

    Famoso, Barbara; La Rocca, Paola; Riggi, Francesco

    2005-01-01

    An educational study of the barometric effect of cosmic rays was carried out using an inexpensive experimental set-up that allowed for long-term monitoring of atmospheric pressure and cosmic ray flux as measured in a Geiger counter. The investigation was intended as a pilot study in view of ongoing involvements of high-school teams operating…

  1. Simulation of atmospheric temperature effects on cosmic ray muon flux

    SciTech Connect

    Tognini, Stefano Castro; Gomes, Ricardo Avelino

    2015-05-15

    The collision between a cosmic ray and an atmosphere nucleus produces a set of secondary particles, which will decay or interact with other atmosphere elements. This set of events produced a primary particle is known as an extensive air shower (EAS) and is composed by a muonic, a hadronic and an electromagnetic component. The muonic flux, produced mainly by pions and kaons decays, has a dependency with the atmosphere’s effective temperature: an increase in the effective temperature results in a lower density profile, which decreases the probability of pions and kaons to interact with the atmosphere and, consequently, resulting in a major number of meson decays. Such correlation between the muon flux and the atmosphere’s effective temperature was measured by a set of experiments, such as AMANDA, Borexino, MACRO and MINOS. This phenomena can be investigated by simulating the final muon flux produced by two different parameterizations of the isothermal atmospheric model in CORSIKA, where each parameterization is described by a depth function which can be related to the muon flux in the same way that the muon flux is related to the temperature. This research checks the agreement among different high energy hadronic interactions models and the physical expected behavior of the atmosphere temperature effect by analyzing a set of variables, such as the height of the primary interaction and the difference in the muon flux.

  2. On scale-dependent cosmic shear systematic effects

    NASA Astrophysics Data System (ADS)

    Kitching, T. D.; Taylor, A. N.; Cropper, M.; Hoekstra, H.; Hood, R. K. E.; Massey, R.; Niemi, S.

    2016-01-01

    In this paper, we investigate the impact that realistic scale-dependent systematic effects may have on cosmic shear tomography. We model spatially varying residual galaxy ellipticity and galaxy size variations in weak lensing measurements and propagate these through to predicted changes in the uncertainty and bias of cosmological parameters. We show that the survey strategy - whether it is regular or randomized - is an important factor in determining the impact of a systematic effect: a purely randomized survey strategy produces the smallest biases, at the expense of larger parameter uncertainties, and a very regularized survey strategy produces large biases, but unaffected uncertainties. However, by removing, or modelling, the affected scales (ℓ-modes) in the regular cases the biases are reduced to negligible levels. We find that the integral of the systematic power spectrum is not a good metric for dark energy performance, and we advocate that systematic effects should be modelled accurately in real space, where they enter the measurement process, and their effect subsequently propagated into power spectrum contributions.

  3. Drift Effects on the Galactic Cosmic Ray Modulation

    NASA Astrophysics Data System (ADS)

    Laurenza, M.; Vecchio, A.; Storini, M.; Carbone, V.

    2014-02-01

    Cosmic ray (CR) modulation is driven by both solar activity and drift effects in the heliosphere, although their role is only qualitatively understood as it is difficult to connect the CR variations to their sources. In order to address this problem, the Empirical Mode Decomposition technique has been applied to the CR intensity, recorded by three neutron monitors at different rigidities (Climax, Rome, and Huancayo-Haleakala (HH)), the sunspot area, as a proxy for solar activity, the heliospheric magnetic field magnitude, directly related to CR propagation, and the tilt angle (TA) of the heliospheric current sheet (HCS), which characterizes drift effects on CRs. A prominent periodicity at ~six years is detected in all the analyzed CR data sets and it is found to be highly correlated with changes in the HCS inclination at the same timescale. In addition, this variation is found to be responsible for the main features of the CR modulation during periods of low solar activity, such as the flat (peaked) maximum in even (odd) solar cycles. The contribution of the drift effects to the global Galactic CR modulation has been estimated to be between 30% and 35%, depending on the CR particle energy. Nevertheless, the importance of the drift contribution is generally reduced in periods nearing the sunspot maximum. Finally, threshold values of ~40°, ~45°, and >55° have been derived for the TA, critical for the CR modulation at the Climax, Rome, and HH rigidity thresholds, respectively.

  4. Drift effects on the galactic cosmic ray modulation

    SciTech Connect

    Laurenza, M.; Storini, M.; Carbone, V.

    2014-02-01

    Cosmic ray (CR) modulation is driven by both solar activity and drift effects in the heliosphere, although their role is only qualitatively understood as it is difficult to connect the CR variations to their sources. In order to address this problem, the Empirical Mode Decomposition technique has been applied to the CR intensity, recorded by three neutron monitors at different rigidities (Climax, Rome, and Huancayo-Haleakala (HH)), the sunspot area, as a proxy for solar activity, the heliospheric magnetic field magnitude, directly related to CR propagation, and the tilt angle (TA) of the heliospheric current sheet (HCS), which characterizes drift effects on CRs. A prominent periodicity at ∼six years is detected in all the analyzed CR data sets and it is found to be highly correlated with changes in the HCS inclination at the same timescale. In addition, this variation is found to be responsible for the main features of the CR modulation during periods of low solar activity, such as the flat (peaked) maximum in even (odd) solar cycles. The contribution of the drift effects to the global Galactic CR modulation has been estimated to be between 30% and 35%, depending on the CR particle energy. Nevertheless, the importance of the drift contribution is generally reduced in periods nearing the sunspot maximum. Finally, threshold values of ∼40°, ∼45°, and >55° have been derived for the TA, critical for the CR modulation at the Climax, Rome, and HH rigidity thresholds, respectively.

  5. Domain wall magneto-Seebeck effect

    NASA Astrophysics Data System (ADS)

    Krzysteczko, Patryk; Hu, Xiukun; Liebing, Niklas; Sievers, Sibylle; Schumacher, Hans W.

    2015-10-01

    The interplay between charge, spin, and heat currents in magnetic nanostructures subjected to a temperature gradient has led to a variety of novel effects and promising applications studied in the fast-growing field of spin caloritronics. Here, we explore the magnetothermoelectrical properties of an individual magnetic domain wall in a permalloy nanowire. In thermal gradients of the order of few K /μ m along the long wire axis, we find a clear magneto-Seebeck signature due to the presence of a single domain wall. The observed domain wall magneto-Seebeck effect can be explained by the magnetization-dependent Seebeck coefficient of permalloy in combination with the local spin configuration of the domain wall.

  6. Effect of a cosmic string on spin dynamics

    NASA Astrophysics Data System (ADS)

    Chowdhury, Debashree; Basu, B.

    2014-12-01

    In the present paper, we have investigated the role of the cosmic string on spin current and Hall electric field. Due to the background cosmic string, the modified electric field of the system generates renormalized spin-orbit coupling, which induces a modified non-Abelian gauge field. The defect causes a change in the Aharonov-Bohm and Aharonov-Casher phases appearing due to the modified electromagnetic field. In addition, for a time varying electric field we perform explicit analytic calculations to derive the exact form of spin electric field and spin current, which is defect parameter dependent and of oscillating type. Furthermore, in an asymmetric crystal within the Drude model approach we investigate the dependence of the cosmic string parameters on cosmic string induced Hall electric field.

  7. The bispectrum of cosmic string temperature fluctuations including recombination effects

    SciTech Connect

    Regan, Donough; Hindmarsh, Mark E-mail: m.b.hindmarsh@sussex.ac.uk

    2015-10-01

    We calculate the cosmic microwave background temperature bispectrum from cosmic strings, including the contributions from the last scattering surface, using a well-established Gaussian model for the string energy-momentum correlation functions, and a simplified model for the cosmic fluid. We check our approximation for the integrated Sachs-Wolfe (ISW) contribution against the bispectrum obtained from the full sky map of the cosmic string ISW signal used by the Planck team, obtaining good agreement. We validate our model for the last scattering surface contribution by comparing the predicted temperature power spectrum with that obtained from a full Boltzmann code treatment applied to the Unconnected Segment Model of a string network. We find that including the last scattering contribution has only a small impact on the upper limit on the string tension resulting from the bispectrum at Planck resolutions, and argue that the bispectrum is unlikely to be competitive with the power spectrum at any resolution.

  8. Cosmic-Ray Effects of Propagating Shocks Including the Heliosheath

    NASA Astrophysics Data System (ADS)

    Jokipii, J. R.; Kota, J.

    2001-08-01

    It has been known for a long time (Jokipii, et al, 1993) that the e~@ects of tt he heliosphere on cosmic rays extends beyond the termination shock and into the heliosheath. The inclusion of the region beyond the termination shock into models of modulation is still relatively recent. The previously-published model resultshave all been for a stationary system. We have modi~Aed our two-dimensional heliosperic cosmic-ray simulation code to be time dependent and to include a propagating shock wave which propagates out from the Sun and into the Heliosheath. The code follows the time variation of the intensity of both galacticand anomalous cosmic rays as the shock propagates past the point of observation and beyond. The results from the model simulations will be compared with recent observational results suggesting e~@ects of the heliosheath on galacticc and anomalous cosmic rays.

  9. The effect of cosmic rays on thunderstorm electricity

    NASA Technical Reports Server (NTRS)

    Bragin, Y. A.

    1975-01-01

    The inflow of charges of small ions, formed by cosmic rays, into thunderstorm cells is estimated on the basis of rocket measurements of ionic concentrations below 90 km. Out of the two processes that form the thunderstorm charge (generation and separation of charges), the former is supposed to be caused by cosmic rays, and the nature of separation is assumed to be the same as in other thunderstorm theories.

  10. Solar cosmic ray effects in the lower ionosphere

    NASA Technical Reports Server (NTRS)

    Shirochkov, A. V.

    1989-01-01

    The polar cap absorption (PCA) events are the most remarkable geophysical phenomena in the high latitude ionosphere. Their effects are extended on the whole polar region in both hemispheres. The PCA events are caused by the intense fluxes of the solar cosmic rays (SCR) which are generated by the solar proton flares. Entering into the Earth's magnetosphere and ionosphere the SCR fluxes create excessive anomal ionization at the ionospheric heights of 50 to 100 km which exceeds usual undisturbed level of ionization in several orders of magnitude. The PCA events can be considered as catastrophic in relation to the polar ionosphere because all radio systems using ionospheric radio channels ceased to operate during these events. On the other hand the abnormally high level of ionization in the ionospheric D region during the PCA events create excellent opportunities to conduct fruitful aeronomical research for the lower ionosphere. Obvious scientific and practical importance of the PCA events leads to publishing of special PCA catalogues. The ionospheric effects caused by the SCR fluxes were profoundly described in the classical paper (Bailey, 1964). Nevertheless several aspects of this problem were not studied properly. An attempt is made to clarify these questions.

  11. Effects of Rayleigh scattering on the CMB and cosmic structure

    NASA Astrophysics Data System (ADS)

    Alipour, Elham; Sigurdson, Kris; Hirata, Christopher M.

    2015-04-01

    During and after recombination, in addition to Thomson scattering with free electrons, photons also couple to neutral hydrogen and helium atoms through Rayleigh scattering. This coupling influences both cosmic microwave background (CMB) anisotropies and the distribution of matter in the Universe. The frequency dependence of the Rayleigh cross section breaks the thermal nature of CMB temperature and polarization anisotropies and effectively doubles the number of variables needed to describe CMB intensity and polarization statistics, while the additional atomic coupling changes the matter distribution and the lensing of the CMB. We introduce a new method to capture the effects of Rayleigh scattering on cosmological power spectra. Rayleigh scattering modifies CMB temperature and polarization anisotropies at the ˜1 % level at 35 GHz (scaling ∝ν4 ), and modifies matter correlations by as much as ˜0.3 %. We show the Rayleigh signal, especially the cross-spectra between the thermal (Rayleigh) E -polarization and Rayleigh (thermal) intensity signal, may be detectable with future CMB missions even in the presence of foregrounds, and how this new information might help to better constrain the cosmological parameters.

  12. Alfven wave transport effects in the time evolution of parallel cosmic-ray modified shocks

    NASA Technical Reports Server (NTRS)

    Jones, T. W.

    1993-01-01

    Some of the issues associated with a more complete treatment of Alfven transport in cosmic ray shocks are explored qualitatively. The treatment is simplified in some important respects, but some new issues are examined and for the first time a nonlinear, time dependent study of plane cosmic ray mediated shocks with both the entropy producing effects of wave dissipation and effects due to the Alfven wave advection of the cosmic ray relative to the gas is included. Examination of the direct consequences of including the pressure and energy of the Alfven waves in the formalism began.

  13. Effective action in spherical domains

    NASA Astrophysics Data System (ADS)

    Dowker, J. S.

    1994-05-01

    The effective action on an orbifolded sphere is computed for minimally coupled scalar fields. The results are presented in terms of derivatives of Barnes ζ-functions and it is shown how these may be evaluated. Numerical values are shown. An analytical, heat-kernel derivation of the Cesàro-Fedorov formula for the number of symmetry planes of a regular solid is also presented.

  14. Atmospheric Effects on Cosmic Ray Air Showers Observed with HAWC

    NASA Astrophysics Data System (ADS)

    Young, Steven

    2014-01-01

    The High Altitude Water Cherenkov Gamma Ray detector (HAWC), currently under construction on the Sierra Negra volcano near Puebla, Mexico, can be used to study solar physics with its scaler data acquisition system. Increases in the scaler rates are used to observe GeV cosmic rays from solar flares while decreases in the rates show the heliospheric disturbances associated with coronal mass ejections. However, weather conditions and height-dependent state variables such as pressure and temperature affect the production of extensive particle air showers that can be detected by the scaler system. To see if these atmospheric effects can be removed, we obtained local weather data from the Global Data Assimilation System (GDAS) and the local weather station at HAWC. The scaler pulse rates were then correlated to the pressure and temperature. We present data from a Forbush decrease observed by HAWC following a significant coronal mass ejection in April 2013, and describe our efforts to remove atmospheric variations from the scaler counts. This work was partially supported by the National Science Foundation’s REU program through NSF Award AST-1004881 to the University of Wisconsin-Madison.

  15. A gamma-ray testing technique for spacecraft. [considering cosmic radiation effects

    NASA Technical Reports Server (NTRS)

    Gribov, B. S.; Repin, N. N.; Sakovich, V. A.; Sakharov, V. M.

    1977-01-01

    The simulated cosmic radiation effect on a spacecraft structure is evaluated by gamma ray testing in relation to structural thickness. A drawing of the test set-up is provided and measurement errors are discussed.

  16. Cosmic bubble and domain wall instabilities I: parametric amplification of linear fluctuations

    SciTech Connect

    Braden, Jonathan; Bond, J. Richard; Mersini-Houghton, Laura

    2015-03-03

    This is the first paper in a series where we study collisions of nucleated bubbles taking into account the effects of small initial (quantum) fluctuations in a fully 3+1-dimensional setting. In this paper, we consider the evolution of linear fluctuations around highly symmetric though inhomogeneous backgrounds. In particular, we demonstrate that a large degree of asymmetry develops over time from tiny initial fluctuations superposed upon planar and SO(2,1) symmetric backgrounds. These fluctuations are inevitable consequences of zero-point vacuum oscillations, so excluding them by enforcing a high degree of spatial symmetry is inconsistent in a quantum treatment. To simplify the analysis we consider the limit of two colliding planar walls, with mode functions for the fluctuations characterized by the wavenumber transverse to the collision direction and a longitudinal shape along the collision direction x, which we solve for. In the linear regime, the fluctuations obey a linear wave equation with a time- and space-dependent mass m{sub eff}(x,t). In situations where the walls collide multiple times, m{sub eff} oscillates in time. We use Floquet theory to study the evolution of the fluctuations and generalize the calculations familiar from the preheating literature to the case with many coupled degrees of freedom. The inhomogeneous case has bands of unstable transverse wavenumbers k{sub ⊥} whose corresponding mode functions grow exponentially. By examining the detailed spatial structure of the mode functions in x, we identify both broad and narrow parametric resonance generalizations of the homogeneous m{sub eff}(t) case of preheating. The unstable k{sub ⊥} modes are longitudinally localized, yet can be described as quasiparticles in the Bogoliubov sense. We define an effective occupation number and show they are created in bursts for the case of well-defined collisions in the background. The transverse-longitudinal coupling accompanying nonlinearity radically

  17. IONIZATION IN ATMOSPHERES OF BROWN DWARFS AND EXTRASOLAR PLANETS. IV. THE EFFECT OF COSMIC RAYS

    SciTech Connect

    Rimmer, P. B.; Helling, Ch.

    2013-09-10

    Cosmic rays provide an important source for free electrons in Earth's atmosphere and also in dense interstellar regions where they produce a prevailing background ionization. We utilize a Monte Carlo cosmic ray transport model for particle energies of 10{sup 6} eV cosmic ray transport model for particle energies of 10{sup 9} eV cosmic ray enhancement of free electrons in substellar atmospheres of free-floating objects. The cosmic ray calculations are applied to DRIFT-PHOENIX model atmospheres of an example brown dwarf with effective temperature T{sub eff} = 1500 K, and two example giant gas planets (T{sub eff} = 1000 K, 1500 K). For the model brown dwarf atmosphere, the electron fraction is enhanced significantly by cosmic rays when the pressure p{sub gas} < 10{sup -2} bar. Our example giant gas planet atmosphere suggests that the cosmic ray enhancement extends to 10{sup -4}-10{sup -2} bar, depending on the effective temperature. For the model atmosphere of the example giant gas planet considered here (T{sub eff} = 1000 K), cosmic rays bring the degree of ionization to f{sub e} {approx}> 10{sup -8} when p{sub gas} < 10{sup -8} bar, suggesting that this part of the atmosphere may behave as a weakly ionized plasma. Although cosmic rays enhance the degree of ionization by over three orders of magnitude in the upper atmosphere, the effect is not likely to be significant enough for sustained coupling of the magnetic field to the gas.

  18. Framing Effects: Dynamics and Task Domains

    PubMed

    Wang

    1996-11-01

    The author examines the mechanisms and dynamics of framing effects in risky choices across three distinct task domains (i.e., life-death, public property, and personal money). The choice outcomes of the problems presented in each of the three task domains had a binary structure of a sure thing vs a gamble of equal expected value; the outcomes differed in their framing conditions and the expected values, raging from 6000, 600, 60, to 6, numerically. It was hypothesized that subjects would become more risk seeking, if the sure outcome was below their aspiration level (the minimum requirement). As predicted, more subjects preferred the gamble when facing the life-death choice problems than facing the counterpart problems presented in the other two task domains. Subjects' risk preference varied categorically along the group size dimension in the life-death domain but changed more linearly over the expected value dimension in the monetary domain. Framing effects were observed in 7 of 13 pairs of problems, showing a positive frame-risk aversion and negative frame-risk seeking relationship. In addition, two types of framing effects were theoretically defined and empirically identified. A bidirectional framing effect involves a reversal in risk preference, and occurs when a decision maker's risk preference is ambiguous or weak. Four bidirectional effects were observed; in each case a majority of subjects preferred the sure outcome under a positive frame but the gamble under a negative frame. In contrast, a unidirectional framing effect refers to a preference shift due to the framing of choice outcomes: A majority of subjects preferred one choice outcome (either the sure thing or the gamble) under both framing conditions, with positive frame augmented the preference for the sure thing and negative frame augmented the preference for the gamble. These findings revealed some dynamic regularities of framing effects and posed implications for developing predictive and testable

  19. 1/R multidimensional gravity with form-fields: Stabilization of extra dimensions, cosmic acceleration, and domain walls

    SciTech Connect

    Saidov, Tamerlan; Zhuk, Alexander

    2007-04-15

    We study multidimensional gravitational models with scalar curvature nonlinearity of the type 1/R and with form-fields (fluxes) as a matter source. It is assumed that the higher dimensional space-time undergoes Freund-Rubin-like spontaneous compactification to a warped product manifold. It is shown that for certain parameter regions the model allows for a freezing stabilization of the internal space near the positive minimum of the effective potential which plays the role of the positive cosmological constant. This cosmological constant provides the observable late-time accelerating expansion of the Universe if the parameters of the model are fine tuned. Additionally, the effective potential has the saddle point. It results in domain walls in the Universe. We show that these domain walls do not undergo inflation.

  20. 1/R multidimensional gravity with form-fields: Stabilization of extra dimensions, cosmic acceleration, and domain walls

    NASA Astrophysics Data System (ADS)

    Saidov, Tamerlan; Zhuk, Alexander

    2007-04-01

    We study multidimensional gravitational models with scalar curvature nonlinearity of the type 1/R and with form-fields (fluxes) as a matter source. It is assumed that the higher dimensional space-time undergoes Freund-Rubin-like spontaneous compactification to a warped product manifold. It is shown that for certain parameter regions the model allows for a freezing stabilization of the internal space near the positive minimum of the effective potential which plays the role of the positive cosmological constant. This cosmological constant provides the observable late-time accelerating expansion of the Universe if the parameters of the model are fine tuned. Additionally, the effective potential has the saddle point. It results in domain walls in the Universe. We show that these domain walls do not undergo inflation.

  1. Atmospheric effects of stellar cosmic rays on Earth-like exoplanets orbiting M-dwarfs

    NASA Astrophysics Data System (ADS)

    Tabataba-Vakili, F.; Grenfell, J. L.; Grießmeier, J.-M.; Rauer, H.

    2016-01-01

    M-dwarf stars are generally considered favourable for rocky planet detection. However, such planets may be subject to extreme conditions due to possible high stellar activity. The goal of this work is to determine the potential effect of stellar cosmic rays on key atmospheric species of Earth-like planets orbiting in the habitable zone of M-dwarf stars and show corresponding changes in the planetary spectra. We build upon the cosmic rays model scheme of previous works, who considered cosmic ray induced NOx production, by adding further cosmic ray induced production mechanisms (e.g. for HOx) and introducing primary protons of a wider energy range (16 MeV-0.5 TeV). Previous studies suggested that planets in the habitable zone that are subject to strong flaring conditions have high atmospheric methane concentrations, while their ozone biosignature is completely destroyed. Our current study shows, however, that adding cosmic ray induced HOx production can cause a decrease in atmospheric methane abundance of up to 80%. Furthermore, the cosmic ray induced HOx molecules react with NOx to produce HNO3, which produces strong HNO3 signals in the theoretical spectra and reduces NOx-induced catalytic destruction of ozone so that more than 25% of the ozone column remains. Hence, an ozone signal remains visible in the theoretical spectrum (albeit with a weaker intensity) when incorporating the new cosmic ray induced NOx and HOx schemes, even for a constantly flaring M-star case. We also find that HNO3 levels may be high enough to be potentially detectable. Since ozone concentrations, which act as the key shield against harmful UV radiation, are affected by cosmic rays via NOx-induced catalytic destruction of ozone, the impact of stellar cosmic rays on surface UV fluxes is also studied.

  2. Investigating the Effect of Cosmic Opacity on Standard Candles

    NASA Astrophysics Data System (ADS)

    Hu, J.; Yu, H.; Wang, F. Y.

    2017-02-01

    Standard candles can probe the evolution of dark energy over a large redshift range. But the cosmic opacity can degrade the quality of standard candles. In this paper, we use the latest observations, including Type Ia supernovae (SNe Ia) from the “joint light-curve analysis” sample and Hubble parameters, to probe the opacity of the universe. A joint fitting of the SNe Ia light-curve parameters, cosmological parameters, and opacity is used in order to avoid the cosmological dependence of SNe Ia luminosity distances. The latest gamma-ray bursts are used in order to explore the cosmic opacity at high redshifts. The cosmic reionization process is considered at high redshifts. We find that the sample supports an almost transparent universe for flat ΛCDM and XCDM models. Meanwhile, free electrons deplete photons from standard candles through (inverse) Compton scattering, which is known as an important component of opacity. This Compton dimming may play an important role in future supernova surveys. From analysis, we find that about a few per cent of the cosmic opacity is caused by Compton dimming in the two models, which can be corrected.

  3. Effects of a wavy neutral sheet on cosmic ray anisotropies

    NASA Technical Reports Server (NTRS)

    Kota, J.; Jokipii, J. R.

    1985-01-01

    The first results of a three-dimensional numerical code calculating cosmic ray anisotropies is presented. The code includes diffusion, convection, adiabatic cooling, and drift in an interplanetary magnetic field model containing a wavy neutral sheet. The 3-D model can reproduce all the principal observations for a reasonable set of parameters.

  4. The effect of cosmic ray intensity variations and geomagnetic disturbances on the physiological state of aviators

    NASA Astrophysics Data System (ADS)

    Papailiou, M.; Mavromichalaki, H.; Kudela, K.; Stetiarova, J.; Dimitrova, S.; Giannaropoulou, E.

    2011-09-01

    Over the last few years various researches have reached the conclusion that cosmic ray variations and geomagnetic disturbances are related to the condition of the human physiological state. In this study medical data regarding 4018 Slovak aviators were analyzed in relation to daily variations of cosmic ray and geomagnetic activity. Specifically daily data concerning mean values of heart rate which were registered during the medical examinations of the Slovak aviators, were related to daily variations of cosmic ray intensity, as measured by the Neutron Monitor Station on Lomnicky Stit (http://neutronmonitor.ta3.sk/realtime.php3) and the high resolution neutron monitor database (http://www.nmdb.eu) and daily variations of Dst and Ap geomagnetic indices. All subjects were men in good health of age 18-60 yrs. This particular study refers to the time period from 1 January 1994 till 31 December 2002. Statistical methods were applied to establish a statistical significance of the effect of geomagnetic activity levels and cosmic ray intensity variations on the aforementioned physiological parameters for the whole group. The Pearson r-coefficients were calculated and the Analysis of Variance (ANOVA) method was applied to establish the statistical significance levels (p-values) of the effect of geomagnetic activity and cosmic ray intensity variations on heart rate up to three days before and three days after the respective events. Results show that there is an underlying effect of geomagnetic activity and cosmic ray intensity variations on the cardiovascular functionality.

  5. Effects of Martian dust storms on ionization profiles and surface dose rates from cosmic rays

    NASA Astrophysics Data System (ADS)

    Norman, R. B.; Gronoff, G.; Mertens, C. J.

    2012-12-01

    Global dust storms can engulf Mars and distribute dust throughout the atmosphere. The change in composition and density of the atmosphere due to dust storms affects the ionization rate due to cosmic rays impingent on Mars. To model the effect of dust storms on the Martian ionization profile, the Badhwar-O'Neill cosmic ray spectrum model has been adapted to Mars and used as an input in the NAIRAS model. NAIRAS is a cosmic ray irradiation model adapted for fast computations and has been applied to the Martian atmosphere. Full atmosphere ionization profiles for solar maximum and solar minimum conditions during both dust storms and quiet times are reported. The contribution of heavy ions and secondary particles to the ionization profile are also reported. Dose rates at the surface due to cosmic radiation are shown to not vary significantly due to the dust storms.

  6. Biotropic Effect of Radiation Conditions on Orbital Cosmic Stations

    NASA Astrophysics Data System (ADS)

    Tsetlin, Vladimir; Ushakov, Igor; Gurieva, Tamar; Moisa, Svetlana; Zotin, Alexei; Lobanov, Alexei

    On the orbit of pilot orbital stations the crews undergo to low doses of chronic irradiation of cosmic radiation. The studying of radiobiological effects in different living systems were carried out in the ship’s side (OC “MIR” and ICS) and model surface experiments (power dose 200 mGy/day, density of neutron flow 30 particles/sm2 sec). It was shown that ionized radiation effects on embryonal development of Japanese quail embryo, inducing morphological disturbances in 12% of embryos. Many years ontogenesis (more 15 years of life in OC “MIR”) of microbial association evoked replacement of dominant types of micromycetes and bacterium and increasing of colony-formed units (CFU) in four orders. In laboratory low doses of γ-radiation induced the increasing of flight strain biomass of Aspergillus niger that corresponds to a radiation hormezis and also the increasing of radio-sensitivity. Moreover, under γ-neutron radiation were marked some deviations in morphology of supporting cell and numerous head falls of Aspergillus niger. The irradiation of Protozoa by low doses led to that spontaneous motion activity of spirostoms (Spirostomum ambiguum Ehbg.) accommodated in water processing by mixed γ-neutron radiation decreased twice that testified the fact that the definite factor of γ-neutron radiation effect is the changing of water medium state. In dry seeds of the highest plants wetting in water of preliminary low doses α-and γ-irradiation <10 cGy (increasing natural radiation background in 100-500 times) and accommodating in hypo-magnetic camera (induction of magnetic field in 100-300 times lower than geomagnetic one) the germination of seeds was higher approximately twice under γ-radiation. Low doses of γ-radiation decreased and α-radiation increased a negative influence of hypo-magnetic field on these processes. It was shown that hypomagnetic field occurred, in general, beneficial effect on the development of Planorbarius corneus: the portion of

  7. The Effects of Dark Matter Annihilation on Cosmic Reionization

    NASA Astrophysics Data System (ADS)

    Kaurov, Alexander A.; Hooper, Dan; Gnedin, Nickolay Y.

    2016-12-01

    We revisit the possibility of constraining the properties of dark matter (DM) by studying the epoch of cosmic reionization. Previous studies have shown that DM annihilation was unlikely to have provided a large fraction of the photons which ionized the universe, but instead played a subdominant role relative to stars and quasars. The DM might, however, have begun to efficiently annihilate with the formation of primordial microhalos at z ˜ 100-200, much earlier than the formation of the first stars. Therefore, if DM annihilation ionized the universe at even the percent level over the interval z ˜ 20-100, it could leave a significant imprint on the global optical depth, τ. Moreover, we show that cosmic microwave background polarization data and future 21 cm measurements will enable us to more directly probe the DM contribution to the optical depth. In order to compute the annihilation rate throughout the epoch of reionization, we adopt the latest results from structure formation studies and explore the impact of various free parameters on our results. We show that future measurements could make it possible to place constraints on the DM’s annihilation cross-sections, which are at a level comparable to those obtained from the observations of dwarf galaxies, cosmic-ray measurements, and studies of recombination.

  8. The effects of Dark Matter annihilation on cosmic reionization

    SciTech Connect

    Kaurov, Alexander A.; Hooper, Dan; Gnedin, Nickolay Y.

    2016-12-15

    We revisit the possibility of constraining the properties of dark matter (DM) by studying the epoch of cosmic reionization. Previous studies have shown that DM annihilation was unlikely to have provided a large fraction of the photons that ionized the universe, but instead played a subdominant role relative to stars and quasars. The DM, however, begins to efficiently annihilate with the formation of primordial microhalos at $z\\sim100-200$, much earlier than the formation of the first stars. Therefore, if DM annihilation ionized the universe at even the percent level over the interval $z \\sim 20-100$, it can leave a significant imprint on the global optical depth, $\\tau$. Moreover, we show that cosmic microwave background (CMB) polarization data and future 21 cm measurements will enable us to more directly probe the DM contribution to the optical depth. In order to compute the annihilation rate throughout the epoch of reionization, we adopt the latest results from structure formation studies and explore the impact of various free parameters on our results. Here, we show that future measurements could make it possible to place constraints on the dark matter's annihilation cross section that are at a level comparable to those obtained from the observations of dwarf galaxies, cosmic ray measurements, and studies of recombination.

  9. The effects of Dark Matter annihilation on cosmic reionization

    DOE PAGES

    Kaurov, Alexander A.; Hooper, Dan; Gnedin, Nickolay Y.

    2016-12-15

    We revisit the possibility of constraining the properties of dark matter (DM) by studying the epoch of cosmic reionization. Previous studies have shown that DM annihilation was unlikely to have provided a large fraction of the photons that ionized the universe, but instead played a subdominant role relative to stars and quasars. The DM, however, begins to efficiently annihilate with the formation of primordial microhalos atmore » $$z\\sim100-200$$, much earlier than the formation of the first stars. Therefore, if DM annihilation ionized the universe at even the percent level over the interval $$z \\sim 20-100$$, it can leave a significant imprint on the global optical depth, $$\\tau$$. Moreover, we show that cosmic microwave background (CMB) polarization data and future 21 cm measurements will enable us to more directly probe the DM contribution to the optical depth. In order to compute the annihilation rate throughout the epoch of reionization, we adopt the latest results from structure formation studies and explore the impact of various free parameters on our results. Here, we show that future measurements could make it possible to place constraints on the dark matter's annihilation cross section that are at a level comparable to those obtained from the observations of dwarf galaxies, cosmic ray measurements, and studies of recombination.« less

  10. EFFECT OF FINITE LARMOR RADIUS ON COSMIC-RAY PENETRATION INTO AN INTERPLANETARY MAGNETIC FLUX ROPE

    SciTech Connect

    Kubo, Yuki; Shimazu, Hironori

    2010-09-01

    We discuss a mechanism for cosmic-ray penetration into an interplanetary magnetic flux rope, particularly the effect of the finite Larmor radius and magnetic field irregularities. First, we derive analytical solutions for cosmic-ray behavior inside a magnetic flux rope, on the basis of the Newton-Lorentz equation of a particle, to investigate how cosmic rays penetrate magnetic flux ropes under an assumption of there being no scattering by small-scale magnetic field irregularities. The results show that the behavior of a particle is determined by only one parameter f{sub 0}, that is, the ratio of the Larmor radius at the flux rope axis to the flux rope radius. The analytical solutions show that cosmic rays cannot penetrate into the inner region of a flux rope by only gyration and gradient-curvature drift in the case of small f{sub 0}. Next, we perform a numerical simulation of a cosmic-ray penetration into an interplanetary magnetic flux rope by adding small-scale magnetic field irregularities. The results show that cosmic rays can penetrate into a magnetic flux rope even in the case of small f{sub 0} because of the effect of small-scale magnetic field irregularities. This simulation also shows that a cosmic-ray density distribution is greatly different from that deduced from a guiding center approximation because of the effect of the finite Larmor radius and magnetic field irregularities for the case of a moderate to large Larmor radius compared to the flux rope radius.

  11. Effects of ordinary and superconducting cosmic strings on primordial nucleosynthesis

    NASA Technical Reports Server (NTRS)

    Hodges, Hardy M.; Turner, Michael S.

    1988-01-01

    A precise calculation is done of the primordial nucleosynthesis constraint on the energy per length of ordinary and superconducting cosmic strings. A general formula is provided for the constraint on the string tension for ordinary strings. Using the current values for the various parameters that describe the evolution of loops, the constraint for ordinary strings is G mu less than 2.2 x 10 to the minus 5 power. Our constraint is weaker than previously quoted limits by a factor of approximately 5. For superconducting loops, with currents generated by primordial magnetic fields, the constraint can be less or more stringent than this limit, depending on the strength of the magnetic field. It is also found in this case that there is a negligible amount of entropy production if the electromagnetic radiation from strings thermalizes with the radiation background.

  12. Birth order effects on autism symptom domains.

    PubMed

    Reichenberg, Abraham; Smith, Christopher; Schmeidler, James; Silverman, Jeremy M

    2007-03-30

    Autism is predominantly genetically determined. Evidence supports familiality of the main sets of behavioral characteristics that define the syndrome of autism; however, possible non-genetic effects have also been suggested. The present study compared levels of autism symptom domains, as measured by the Autism Diagnostic Interview, and useful phrase speech scores between 106 pairs of first- and second-born siblings from multiply affected families. In addition, the intercorrelations between the measures were compared between siblings. The overall mean repetitive behavior total score was significantly higher (worse) in first-born than in second-born siblings. In contrast, first-born siblings had significantly lower (better) useful phrase speech than their younger siblings. Autism social and non-verbal communication scores were significantly correlated in first- and in second-born siblings. However, there was a significant difference in the coefficients between first- and second-born siblings. Performance on the non-verbal communication domain was also significantly and positively correlated with useful phrase speech score in both first- and second-born siblings. It is unclear at this time whether these results are of biologic origin. Nevertheless, the findings suggest that genetic studies in autism using specific levels of familial autism traits as phenotypes should take into account their intercorrelations and birth order effects embedded in the instrument.

  13. Evaluation of World Population-Weighted Effective Dose due to Cosmic Ray Exposure

    PubMed Central

    Sato, Tatsuhiko

    2016-01-01

    After the release of the Report of the United Nations Scientific Committee of the Effects of Atomic Radiation in 2000 (UNSCEAR2000), it became commonly accepted that the world population-weighted effective dose due to cosmic-ray exposure is 0.38 mSv, with a range from 0.3 to 2 mSv. However, these values were derived from approximate projections of altitude and geographic dependences of the cosmic-ray dose rates as well as the world population. This study hence re-evaluated the population-weighted annual effective doses and their probability densities for the entire world as well as for 230 individual nations, using a sophisticated cosmic-ray flux calculation model in tandem with detailed grid population and elevation databases. The resulting world population-weighted annual effective dose was determined to be 0.32 mSv, which is smaller than the UNSCEAR’s evaluation by 16%, with a range from 0.23 to 0.70 mSv covering 99% of the world population. These values were noted to vary with the solar modulation condition within a range of approximately 15%. All assessed population-weighted annual effective doses as well as their statistical information for each nation are provided in the supplementary files annexed to this report. These data improve our understanding of cosmic-ray radiation exposures to populations globally. PMID:27650664

  14. Evaluation of World Population-Weighted Effective Dose due to Cosmic Ray Exposure.

    PubMed

    Sato, Tatsuhiko

    2016-09-21

    After the release of the Report of the United Nations Scientific Committee of the Effects of Atomic Radiation in 2000 (UNSCEAR2000), it became commonly accepted that the world population-weighted effective dose due to cosmic-ray exposure is 0.38 mSv, with a range from 0.3 to 2 mSv. However, these values were derived from approximate projections of altitude and geographic dependences of the cosmic-ray dose rates as well as the world population. This study hence re-evaluated the population-weighted annual effective doses and their probability densities for the entire world as well as for 230 individual nations, using a sophisticated cosmic-ray flux calculation model in tandem with detailed grid population and elevation databases. The resulting world population-weighted annual effective dose was determined to be 0.32 mSv, which is smaller than the UNSCEAR's evaluation by 16%, with a range from 0.23 to 0.70 mSv covering 99% of the world population. These values were noted to vary with the solar modulation condition within a range of approximately 15%. All assessed population-weighted annual effective doses as well as their statistical information for each nation are provided in the supplementary files annexed to this report. These data improve our understanding of cosmic-ray radiation exposures to populations globally.

  15. Evaluation of World Population-Weighted Effective Dose due to Cosmic Ray Exposure

    NASA Astrophysics Data System (ADS)

    Sato, Tatsuhiko

    2016-09-01

    After the release of the Report of the United Nations Scientific Committee of the Effects of Atomic Radiation in 2000 (UNSCEAR2000), it became commonly accepted that the world population-weighted effective dose due to cosmic-ray exposure is 0.38 mSv, with a range from 0.3 to 2 mSv. However, these values were derived from approximate projections of altitude and geographic dependences of the cosmic-ray dose rates as well as the world population. This study hence re-evaluated the population-weighted annual effective doses and their probability densities for the entire world as well as for 230 individual nations, using a sophisticated cosmic-ray flux calculation model in tandem with detailed grid population and elevation databases. The resulting world population-weighted annual effective dose was determined to be 0.32 mSv, which is smaller than the UNSCEAR’s evaluation by 16%, with a range from 0.23 to 0.70 mSv covering 99% of the world population. These values were noted to vary with the solar modulation condition within a range of approximately 15%. All assessed population-weighted annual effective doses as well as their statistical information for each nation are provided in the supplementary files annexed to this report. These data improve our understanding of cosmic-ray radiation exposures to populations globally.

  16. Quantification of seasonal biomass effects on cosmic-ray soil water content determination

    NASA Astrophysics Data System (ADS)

    Baatz, R.; Bogena, H. R.; Hendricks Franssen, H.; Huisman, J. A.; Qu, W.; Montzka, C.; Korres, W.; Vereecken, H.

    2013-12-01

    The novel cosmic-ray soil moisture probes (CRPs) measure neutron flux density close to the earth surface. High energy cosmic-rays penetrate the Earth's atmosphere from the cosmos and become moderated by terrestrial nuclei. Hydrogen is the most effective neutron moderator out of all chemical elements. Therefore, neutron flux density measured with a CRP at the earth surface correlates inversely with the hydrogen content in the CRP's footprint. A major contributor to the amount of hydrogen in the sensor's footprint is soil water content. The ability to measure changes in soil water content within the CRP footprint at a larger-than-point scale (~30 ha) and at high temporal resolution (hourly) make these sensors an appealing measurement instrument for hydrologic modeling purposes. Recent developments focus on the identification and quantification of major uncertainties inherent in CRP soil moisture measurements. In this study, a cosmic-ray soil moisture network for the Rur catchment in Western Germany is presented. It is proposed to correct the measured neutron flux density for above ground biomass yielding vegetation corrected soil water content from cosmic-ray measurements. The correction for above ground water equivalents aims to remove biases in soil water content measurements on sites with high seasonal vegetation dynamics such as agricultural fields. Above ground biomass is estimated as function of indices like NDVI and NDWI using regression equations. The regression equations were obtained with help of literature information, ground-based control measurements, a crop growth model and globally available data from the Moderate Resolution Imaging Spectrometer (MODIS). The results show that above ground biomass could be well estimated during the first half of the year. Seasonal changes in vegetation water content yielded biases in soil water content of ~0.05 cm3/cm3 that could be corrected for with the vegetation correction. The vegetation correction has particularly

  17. Evaluation of viscera and other tissues. [cosmic radiation effects

    NASA Technical Reports Server (NTRS)

    Ellis, J. T.; Kraft, L. M.; Lushbaugh, C. C.; Humason, G. L.; Hartroft, W. S.; Porta, E. A.; Bailey, O. T.; Greep, R. O.; Leach, C. S.; Laird, T.

    1975-01-01

    Histopathological findings in the lungs, livers, bone marrows, small intestines, gonads, kidneys, and other tissues of the four pocket mice (Perognathus longimembris) that survived the Apollo XVII flight were evaluated in the light of their immediate environment and as targets of HZE cosmic ray particles. Results of this study failed to disclose changes that could be ascribed to the HZE particle radiation. Decreased numbers of erythropoietic cells in the bone marrow of the flight mice were probably related to the increased oxygen pressure. The small intestine showed no changes. Ovaries and testes appeared normal. Two of the three surviving male flight mice displayed early stages of spermatogenesis, just as ground-based controls did at the same season. Abnormalities were also not found in the thyroid, parathyroids, adrenals, or kidneys. The status of the juxtaglomerular apparatus could not be evaluated. The lungs exhibited nonspecific slight reactions. A variety of incidental lesions were noted in the livers of both the flight mice and their controls. The heart muscle showed nothing that could be regarded as pathological. Sections of skeletal muscle examined were free from significant change.

  18. THE EFFECT OF A COSMIC RAY PRECURSOR IN SN 1006?

    SciTech Connect

    Rakowski, Cara E.; Laming, J. Martin; Hwang, Una; Eriksen, Kristoffer A.; Hughes, John P.; Ghavamian, Parviz

    2011-07-01

    Like many young supernova remnants, SN 1006 exhibits what appear to be clumps of ejecta close to or protruding beyond the main blast wave. In this Letter, we examine three such protrusions along the east rim. They are semi-aligned with ejecta fingers behind the shock-front and exhibit emission lines from O VII and O VIII. We first interpret them in the context of an upstream medium modified by the saturated non-resonant Bell instability which enhances the growth of Rayleigh-Taylor instabilities when advected post-shock. We discuss their apparent periodicity if the spacing is determined by properties of the remnant or by a preferred size scale in the cosmic ray precursor. We also briefly discuss the alternative that these structures have an origin in the ejecta structure of the explosion itself. In this case, the young evolutionary age of SN 1006 would imply density structure within the outermost layers of the explosion with potentially important implications for deflagration and detonation in thermonuclear supernova explosion models.

  19. High-energy cosmic rays and the Greisen-Zatsepin-Kuz'min effect.

    PubMed

    Watson, A A

    2014-03-01

    Although cosmic rays were discovered over 100 years ago their origin remains uncertain. They have an energy spectrum that extends from ∼1 GeV to beyond 10(20) eV, where the rate is less than 1 particle per km(2) per century. Shortly after the discovery of the cosmic microwave background in 1965, it was pointed out that the spectrum of cosmic rays should steepen fairly abruptly above about 4 × 10(19) eV, provided the sources are distributed uniformly throughout the Universe. This prediction, by Greisen and by Zatsepin and Kuz'min, has become known as the GZK effect and in this article I discuss the current position with regard to experimental data on the energy spectrum of the highest cosmic-ray energies that have been accumulated in a search that has lasted nearly 50 years. Although there is now little doubt that a suppression of the spectrum exists near the energy predicted, it is by no means certain that this is a manifestation of the GZK effect as it might be that this energy is also close to the maximum to which sources can accelerate particles, with the highest energy beam containing a large fraction of nuclei heavier than protons. The way forward is briefly mentioned.

  20. Measurement and simulation of cosmic rays effects on neutron multiplicity counting

    NASA Astrophysics Data System (ADS)

    Weinmann-Smith, R.; Swinhoe, M. T.; Hendricks, J.

    2016-04-01

    Neutron coincidence and multiplicity counting is a standard technique used to measure uranium and plutonium masses in unknown samples for nuclear safeguards purposes, but background sources of radiation can obscure the results. In particular, high energy cosmic rays can produce large coincidence count contributions. Since some of the events occur in the sample itself, it is impossible to measure the background separately. This effect greatly increases the limit of detection of some low level neutron coincidence counting applications. The cosmic ray capability of MCNP6 was used to calculate the expected coincidence rates from cosmic rays for different sample configurations and experimental measurements were conducted for comparison. Uranium enriched to 66%, lead bricks, and an empty detector were measured in the mini Epithermal Neutron Multiplicity Counter, and MCNP6 simulations were made of the same measurements. The results show that the capability is adequate for predicting the expected background rates. Additional verification of MCNP6 was given by comparison of particle production rates to other publications, increasing confidence in MCNP6's use as a tool to lower the limit of detection. MCNP6 was then used to find particle and source information that would be difficult to detect experimentally. The coincidence count contribution was broken down by particle type for singles, doubles, and triples rates. The coincidence count contribution was broken down by source, from(a , n) , spontaneous fission, and cosmic rays, for each multiplicity.

  1. Relativistic Anandan quantum phase and the Aharonov-Casher effect under Lorentz symmetry breaking effects in the cosmic string spacetime

    NASA Astrophysics Data System (ADS)

    Bakke, K.; Furtado, C.; Belich, H.

    2016-09-01

    From the modified Maxwell theory coupled to gravity, we establish a possible scenario of the violation of the Lorentz symmetry and write an effective metric for the cosmic string spacetime. Then, we investigate the arising of an analogue of the Anandan quantum phase for a relativistic Dirac neutral particle with a permanent magnetic dipole moment in the cosmic string spacetime under Lorentz symmetry breaking effects. Besides, we analyse the influence of the effects of the Lorentz symmetry violation and the topology of the defect on the Aharonov-Casher geometric quantum phase in the nonrelativistic limit.

  2. THE EFFECT OF A DYNAMIC INNER HELIOSHEATH THICKNESS ON COSMIC-RAY MODULATION

    SciTech Connect

    Manuel, R.; Ferreira, S. E. S.; Potgieter, M. S.

    2015-02-01

    The time-dependent modulation of galactic cosmic rays in the heliosphere is studied over different polarity cycles by computing 2.5 GV proton intensities using a two-dimensional, time-dependent modulation model. By incorporating recent theoretical advances in the relevant transport parameters in the model, we showed in previous work that this approach gave realistic computed intensities over a solar cycle. New in this work is that a time dependence of the solar wind termination shock (TS) position is implemented in our model to study the effect of a dynamic inner heliosheath thickness (the region between the TS and heliopause) on the solar modulation of galactic cosmic rays. The study reveals that changes in the inner heliosheath thickness, arising from a time-dependent shock position, does affect cosmic-ray intensities everywhere in the heliosphere over a solar cycle, with the smallest effect in the innermost heliosphere. A time-dependent TS position causes a phase difference between the solar activity periods and the corresponding intensity periods. The maximum intensities in response to a solar minimum activity period are found to be dependent on the time-dependent TS profile. It is found that changing the width of the inner heliosheath with time over a solar cycle can shift the time of when the maximum or minimum cosmic-ray intensities occur at various distances throughout the heliosphere, but more significantly in the outer heliosphere. The time-dependent extent of the inner heliosheath, as affected by solar activity conditions, is thus an additional time-dependent factor to be considered in the long-term modulation of cosmic rays.

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

    NASA Astrophysics Data System (ADS)

    Terrana, Alexandra; Harris, Mary-Jean; Johnson, Matthew C.

    2017-02-01

    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, and 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.

  4. Ultrahigh energy cosmic ray nuclei from extragalactic pulsars and the effect of their Galactic counterparts

    SciTech Connect

    Fang, Ke; Olinto, Angela V.; Kotera, Kumiko E-mail: kotera@iap.fr

    2013-03-01

    The acceleration of ultrahigh energy nuclei in fast spinning newborn pulsars can explain the observed spectrum of ultrahigh energy cosmic rays and the trend towards heavier nuclei for energies above 10{sup 19} eV as reported by the Auger Observatory. Pulsar acceleration implies a hard injection spectrum ( ∼ E{sup −1}) due to pulsar spin down and a maximum energy E{sub max} ∼ Z 10{sup 19} eV due to the limit on the spin rate of neutron stars. We have previously shown that the escape through the young supernova remnant softens the spectrum, decreases slightly the maximum energy, and generates secondary nuclei. Here we show that the distribution of pulsar birth periods and the effect of propagation in the interstellar and intergalactic media modifies the combined spectrum of all pulsars. By assuming a normal distribution of pulsar birth periods centered at 300 ms, we show that the contribution of extragalactic pulsar births to the ultrahigh energy cosmic ray spectrum naturally gives rise to a contribution to very high energy cosmic rays (VHECRs, between 10{sup 16} and 10{sup 18} eV) by Galactic pulsar births. The required injected composition to fit the observed spectrum depends on the absolute energy scale, which is uncertain, differing between Auger Observatory and Telescope Array. The contribution of Galactic pulsar births can also bridge the gap between predictions for cosmic ray acceleration in supernova remnants and the observed spectrum just below the ankle, depending on the composition of the cosmic rays that escape the supernova remnant and the diffusion behavior of VHECRs in the Galaxy.

  5. Modeling the effects of low-LET cosmic rays on electronic components.

    PubMed

    Keating, A; Goncalves, P; Pimenta, M; Brogueira, P; Zadeh, A; Daly, E

    2012-08-01

    The effects of cosmic radiation in single cells, organic tissues and electronics are a major concern for space exploration and manned missions. Standard heavy ions radiation tests employ ion cocktails with energy of the order of 10 MeV per nucleon and with a linear energy transfer ranging from a few MeV cm(2) mg(-1) to hundreds of MeV cm(2) mg(-1). In space, cosmic rays show significant fluxes at energies up to the order of GeV per nucleon. The present work aims at investigating single event damage due to low-, high- and very-high-energy ions. The European Space Agency reference single event upset monitor data are used to support the discussion. Finally, the effect of ionization induced directly by primary particles and ionization induced by recoils produced in an electronic device is investigated for different types of devices.

  6. Ionospheric effects of the cosmic gamma ray burst of 29 March 2003

    NASA Astrophysics Data System (ADS)

    Maeda, Koitiro; Tomizawa, Ichiro; Shibata, Takashi F.; Tokimasa, Noritaka; Saito, Akinori; Maruyama, Takashi

    2005-09-01

    We present evidence for ionospheric effects caused by the gamma ray burst that originated at a cosmological distance. At the time of the strong cosmic gamma-ray burst of 29 March 2003 (GRB030329) that took place in the nighttime in Japan we observed a transient decrease in the strength of the radio noise coming from extraterrestrial sources (cosmic noise) at 38 MHz. We also observed a sudden field-amplitude decrease of an 8.006 MHz transmission signal recorded at a distance of 690 km from the transmitter. These phenomena are interpreted as a result of an ionospheric absorption enhancement due to transient ionization caused by GRB030329. We also report no appreciable effect on the ionospheric electron column content derived using GPS (Global Positioning System) microwave signals.

  7. Effects of Landau-Lifshitz-Gilbert damping on domain growth.

    PubMed

    Kudo, Kazue

    2016-12-01

    Domain patterns are simulated by the Landau-Lifshitz-Gilbert (LLG) equation with an easy-axis anisotropy. If the Gilbert damping is removed from the LLG equation, it merely describes the precession of magnetization with a ferromagnetic interaction. However, even without the damping, domains that look similar to those of scalar fields are formed, and they grow with time. It is demonstrated that the damping has no significant effects on domain growth laws and large-scale domain structure. In contrast, small-scale domain structure is affected by the damping. The difference in small-scale structure arises from energy dissipation due to the damping.

  8. Determination of coupling coefficients at various zenith angles of the basis of the cosmic ray azimuth effect

    NASA Technical Reports Server (NTRS)

    Belskiy, S. A.; Dmitriev, B. A.; Romanov, A. M.

    1975-01-01

    The value of EW asymmetry and coupling coefficients at different zenith angles were measured by means of a double coincidence crossed telescope which gives an opportunity to measure simultaneously the intensity of the cosmic ray hard component at zenith angles from 0 to 84 deg in opposite azimuths. The advantages of determining the coupling coefficients by the cosmic ray azimuth effect as compared to their measurement by the latitudinal effect are discussed.

  9. Virtual impact: visualizing the potential effects of cosmic impact in human history

    SciTech Connect

    Masse, W Bruce; Janecky, David R; Forte, Maurizio; Barrientos, Gustavo

    2009-01-01

    Current models indicate that catastrophic impacts by asteroids and comets capable of killing more than one quarter of Earth's human population have occurred on average once every million years; smaller impacts, such the 1908 Tunguska impact that leveled more than 2,000 square km of Siberian forest, occur every 200-300 years. Therefore, cosmic impact likely significantly affected hominine evolution and conceivably played a role in Holocene period human culture history. Regrettably, few archaeologists are trained to appreciate the nature and potential effects of cosmic impact. We have developed a conceptual model for an extensible set of educational and research tools based on virtual reality collaborative environments to engage archaeologists and the general public on the topic of the role of cosmic impact in human history. Our initial focus is on two documented asteroid impacts in Argentina during the period of 4000 to 1000 B.C. Campo del Cicio resulted in an energy release of around 2-3 megatons (100-150 times the Hiroshima atomic weapon), and left several craters and a strewn field covering 493 km{sup 2} in northeastern Argentina. Rio Cuarto was likely more than 1000 megatons and may have devastated an area greater than 50,000 km{sup 2} in central Argentina. We are focusing on reconstructions of these events and their potential effects on contemporary hunter and gatherers. Our vinual reality tools also introduce interactive variables (e.g., impactor physical properties, climate, vegetation, topography, and social complexity) to allow researchers and students to better investigate and evaluate the factors that significantly influence cosmic impact effects.

  10. Effects of electrically charged dark matter on cosmic microwave background anisotropies

    NASA Astrophysics Data System (ADS)

    Kamada, Ayuki; Kohri, Kazunori; Takahashi, Tomo; Yoshida, Naoki

    2017-01-01

    We examine the possibility that dark matter consists of charged massive particles (CHAMPs) in view of the cosmic microwave background (CMB) anisotropies. The evolution of cosmological perturbations of CHAMPs with other components is followed in a self-consistent manner, without assuming that CHAMPs and baryons are tightly coupled. We incorporate for the first time the "kinetic recoupling" of the Coulomb scattering, which is characteristic of heavy CHAMPs. By a direct comparison of the predicted CMB temperature/polarization autocorrelations in CHAMP models and the observed spectra in the Planck mission, we show that CHAMPs leave sizable effects on them if it is lighter than 1 011 GeV . Our result can be applicable to any CHAMP as long as its lifetime is much longer than the cosmic time at the recombination (˜4 ×1 05 yr ). An application to millicharged particles is also discussed.

  11. The cross-correlation between 3D cosmic shear and the integrated Sachs-Wolfe effect

    NASA Astrophysics Data System (ADS)

    Zieser, Britta; Merkel, Philipp M.

    2016-06-01

    We present the first calculation of the cross-correlation between 3D cosmic shear and the integrated Sachs-Wolfe (iSW) effect. Both signals are combined in a single formalism, which permits the computation of the full covariance matrix. In order to avoid the uncertainties presented by the non-linear evolution of the matter power spectrum and intrinsic alignments of galaxies, our analysis is restricted to large scales, i.e. multipoles below ℓ = 1000. We demonstrate in a Fisher analysis that this reduction compared to other studies of 3D weak lensing extending to smaller scales is compensated by the information that is gained if the additional iSW signal and in particular its cross-correlation with lensing data are considered. Given the observational standards of upcoming weak-lensing surveys like Euclid, marginal errors on cosmological parameters decrease by 10 per cent compared to a cosmic shear experiment if both types of information are combined without a cosmic wave background (CMB) prior. Once the constraining power of CMB data is added, the improvement becomes marginal.

  12. The effect of the solar field reversal on the modulation of galactic cosmic rays

    NASA Technical Reports Server (NTRS)

    Thomas, B. T.; Goldstein, B. E.

    1983-01-01

    There is now a growing awareness that solar cycle related changes in the large-scale structure of the interplanetary magnetic field (IMF) may play an important role in the modulation of galactic cosmic rays. To date, attention focussed on two aspects of the magnetic field structure: large scale compression regions produced by fast solar wind streams and solar flares, both of which are known to vary in intensity and number over the solar cycle, and the variable warp of the heliospheric current sheet. It is suggested that another feature of the solar cycle is worthy of consideration: the field reversal itself. If the Sun reverses its polarity by simply overturning the heliospheric current sheet (northern fields migrating southward and vice-versa) then there may well be an effect on cosmic ray intensity. However, such a simple picture of solar reversal seems improbable. Observations of the solar corona suggest the existence of not one but several current sheets in the heliosphere at solar maximum. The results of a simple calculation to demonstrate that the variation in cosmic ray intensities that will result can be as large as is actually observed over the solar cycle are given.

  13. Cosmic-ray effects in the Gum nebula

    NASA Technical Reports Server (NTRS)

    Ramaty, R.; Boldt, E. A.

    1971-01-01

    The effects of low energy heavy nuclei from the supernova explosion on nearby interstellar space were investigated. In addition to the ionization and heating of the Gum nebula, these particles may produce detectable fluxes of X-rays and gamma rays, both as continuum radiation and line emission.

  14. Effects of cosmic rays on single event upsets

    NASA Technical Reports Server (NTRS)

    Lowe, Calvin W.; Oladipupo, Adebisi O.; Venable, Demetrius D.

    1988-01-01

    The efforts at establishing a research program in space radiation effects are discussed. The research program has served as the basis for training several graduate students in an area of research that is of importance to NASA. In addition, technical support was provided for the Single Event Facility Group at Brookhaven National Laboratory.

  15. Effects of cosmic rays on single event upsets

    NASA Technical Reports Server (NTRS)

    Venable, D. D.; Zajic, V.; Lowe, C. W.; Olidapupo, A.; Fogarty, T. N.

    1989-01-01

    Assistance was provided to the Brookhaven Single Event Upset (SEU) Test Facility. Computer codes were developed for fragmentation and secondary radiation affecting Very Large Scale Integration (VLSI) in space. A computer controlled CV (HP4192) test was developed for Terman analysis. Also developed were high speed parametric tests which are independent of operator judgment and a charge pumping technique for measurement of D(sub it) (E). The X-ray secondary effects, and parametric degradation as a function of dose rate were simulated. The SPICE simulation of static RAMs with various resistor filters was tested.

  16. Effects of cosmic rays on single event upsets

    NASA Astrophysics Data System (ADS)

    Venable, D. D.; Zajic, V.; Lowe, C. W.; Olidapupo, A.; Fogarty, T. N.

    1989-02-01

    Assistance was provided to the Brookhaven Single Event Upset (SEU) Test Facility. Computer codes were developed for fragmentation and secondary radiation affecting Very Large Scale Integration (VLSI) in space. A computer controlled CV (HP4192) test was developed for Terman analysis. Also developed were high speed parametric tests which are independent of operator judgment and a charge pumping technique for measurement of Dit (E). The X-ray secondary effects, and parametric degradation as a function of dose rate were simulated. The SPICE simulation of static RAMs with various resistor filters was tested.

  17. The effects of domain knowledge on metacomprehension accuracy.

    PubMed

    Griffin, Thomas D; Jee, Benjamin D; Wiley, Jennifer

    2009-10-01

    In the present research, we examined the relationship between readers' domain knowledge and their ability to judge their comprehension of novel domain-related material. Participants with varying degrees of baseball knowledge read five texts on baseball-related topics and five texts on non-baseball-related topics, predicted their performance, and completed tests for each text. Baseball knowledge was positively related to absolute accuracy within the baseball domain but was unrelated to relative accuracy within the baseball domain. Also, the readers showed a general underconfidence bias, but the bias was less extreme for higher knowledge readers. The results challenge common assumptions that experts' metacognitive judgments are less accurate than novices'. Results involving topic familiarity ratings and a no-reading control group suggest that higher knowledge readers are not more likely to ignore text-specific cues in favor of a domain familiarity heuristic, but they do appear to make more effective use of domain familiarity in predicting absolute performance levels.

  18. Effects of nuclear cross sections at different energies on the radiation hazard from galactic cosmic rays.

    PubMed

    Lin, Z W; Adams, J H

    2007-03-01

    The radiation hazard for astronauts from galactic cosmic rays (GCR) is a major obstacle to long-duration human space exploration. Space radiation transport codes have been developed to calculate the radiation environment on missions to the Moon, Mars, and beyond. We have studied how uncertainties in fragmentation cross sections at different energies affect the accuracy of predictions from such radiation transport calculations. We find that, in deep space, cross sections at energies between 0.3 and 0.85 GeV/nucleon have the largest effect in solar maximum GCR environments. At the International Space Station, cross sections at higher energies have the largest effect due to the geomagnetic cutoff.

  19. A wind effect of neutron component of cosmic rays at Antarctic station "Mirny"

    NASA Astrophysics Data System (ADS)

    Kobelev, Pavel; Abunin, Artem; Abunina, Mariya; Preobragenskiy, Maksim; Smirnov, Dmitriy; Lukovnikova, Anna

    2016-03-01

    The barometric effect of cosmic ray neutron component was estimated on the example of Antarctic station "Mirny". We used hourly data of continuous monitoring of neutron component and data of the local weather station for 2007-2014. Wind velocity at the Station "Mirny" reaches 20-40 m/s in winter that corresponds to the dynamic pressure of 5-6 mbar and leads to 5 % error in variations of neutron component because of dynamic effects in the atmosphere. The results are of interest for detectors located in high latitude and high mountain regions where the wind velocity can be significant.

  20. Cosmological Implications of the Effects of X-Ray Clusters on the Cosmic Microwave Background

    NASA Technical Reports Server (NTRS)

    Forman, William R.

    1996-01-01

    We have been carrying forward a program to confront X-ray observations of clusters and their evolution as derived from X-ray observatories with observations of the cosmic microwave background radiation (CMBR). In addition to the material covered in our previous reports (including three published papers), most recently we have explored the effects of a cosmological constant on the predicted Sunyaev-Zel'dovich effect from the ensemble of clusters. In this report we summarize that work from which a paper will be prepared.

  1. Determining the Polar Cosmic Ray Effect on Cloud Microphysics and the Earth's Ozone Layer

    NASA Astrophysics Data System (ADS)

    Beckie, Charlene Radons

    water content and effective radius, or altitude specific studies concerning the stratosphere. Continued results from laboratory studies at the CERN facility may lead to a deeper understanding of cosmic ray, cloud microphysics and ozone relationships in nature.

  2. 21 cm signal from cosmic dawn - II. Imprints of the light-cone effects

    NASA Astrophysics Data System (ADS)

    Ghara, Raghunath; Datta, Kanan K.; Choudhury, T. Roy

    2015-11-01

    Details of various unknown physical processes during the cosmic dawn and the epoch of reionization can be extracted from observations of the redshifted 21 cm signal. These observations, however, will be affected by the evolution of the signal along the line of sight which is known as the `light-cone effect'. We model this effect by post-processing a dark matter N-body simulation with an 1D radiative transfer code. We find that the effect is much stronger and dramatic in presence of inhomogeneous heating and Ly α coupling compared to the case where these processes are not accounted for. One finds increase (decrease) in the spherically averaged power spectrum up to a factor of 3 (0.6) at large scales (k ˜ 0.05 Mpc- 1) when the light-cone effect is included, though these numbers are highly dependent on the source model. The effect is particularly significant near the peak and dip-like features seen in the power spectrum. The peaks and dips are suppressed and thus the power spectrum can be smoothed out to a large extent if the width of the frequency band used in the experiment is large. We argue that it is important to account for the light-cone effect for any 21-cm signal prediction during cosmic dawn.

  3. Effects of turbulence on cosmic ray propagation in protostars and young star/disk systems

    SciTech Connect

    Fatuzzo, Marco; Adams, Fred C. E-mail: fca@umich.edu

    2014-05-20

    The magnetic fields associated with young stellar objects are expected to have an hour-glass geometry, i.e., the magnetic field lines are pinched as they thread the equatorial plane surrounding the forming star but merge smoothly onto a background field at large distances. With this field configuration, incoming cosmic rays experience both a funneling effect that acts to enhance the flux impinging on the circumstellar disk and a magnetic mirroring effect that acts to reduce that flux. To leading order, these effects nearly cancel out for simple underlying magnetic field structures. However, the environments surrounding young stellar objects are expected to be highly turbulent. This paper shows how the presence of magnetic field fluctuations affects the process of magnetic mirroring, and thereby changes the flux of cosmic rays striking circumstellar disks. Turbulence has two principle effects: (1) the (single) location of the magnetic mirror point found in the absence of turbulence is replaced with a wide distribution of values. (2) The median of the mirror point distribution moves outward for sufficiently large fluctuation amplitudes (roughly when δB/B {sub 0} > 0.2 at the location of the turbulence-free mirror point); the distribution becomes significantly non-Gaussian in this regime as well. These results may have significant consequences for the ionization fraction of the disk, which in turn dictates the efficiency with which disk material can accrete onto the central object. A similar reduction in cosmic ray flux can occur during the earlier protostellar stages; the decrease in ionization can help alleviate the magnetic braking problem that inhibits disk formation.

  4. Processing and domain selection: Quantificational variability effects

    PubMed Central

    Harris, Jesse A.; Clifton, Charles; Frazier, Lyn

    2014-01-01

    Three studies investigated how readers interpret sentences with variable quantificational domains, e.g., The army was mostly in the capital, where mostly may quantify over individuals or parts (Most of the army was in the capital) or over times (The army was in the capital most of the time). It is proposed that a general conceptual economy principle, No Extra Times (Majewski 2006, in preparation), discourages the postulation of potentially unnecessary times, and thus favors the interpretation quantifying over parts. Disambiguating an ambiguously quantified sentence to a quantification over times interpretation was rated as less natural than disambiguating it to a quantification over parts interpretation (Experiment 1). In an interpretation questionnaire, sentences with similar quantificational variability were constructed so that both interpretations of the sentence would require postulating multiple times; this resulted in the elimination of the preference for a quantification over parts interpretation, suggesting the parts preference observed in Experiment 1 is not reducible to a lexical bias of the adverb mostly (Experiment 2). An eye movement recording study showed that, in the absence of prior evidence for multiple times, readers exhibit greater difficulty when reading material that forces a quantification over times interpretation than when reading material that allows a quantification over parts interpretation (Experiment 3). These experiments contribute to understanding readers’ default assumptions about the temporal properties of sentences, which is essential for understanding the selection of a domain for adverbial quantifiers and, more generally, for understanding how situational constraints influence sentence processing. PMID:25328262

  5. Stability on time-dependent domains: convective and dilution effects

    NASA Astrophysics Data System (ADS)

    Krechetnikov, R.; Knobloch, E.

    2017-03-01

    We explore near-critical behavior of spatially extended systems on time-dependent spatial domains with convective and dilution effects due to domain flow. As a paradigm, we use the Swift-Hohenberg equation, which is the simplest nonlinear model with a non-zero critical wavenumber, to study dynamic pattern formation on time-dependent domains. A universal amplitude equation governing weakly nonlinear evolution of patterns on time-dependent domains is derived and proves to be a generalization of the standard Ginzburg-Landau equation. Its key solutions identified here demonstrate a substantial variety-spatially periodic states with a time-dependent wavenumber, steady spatially non-periodic states, and pulse-train solutions-in contrast to extended systems on time-fixed domains. The effects of domain flow, such as bifurcation delay due to domain growth and destabilization due to oscillatory domain flow, on the Eckhaus instability responsible for phase slips in spatially periodic states are analyzed with the help of both local and global stability analyses. A nonlinear phase equation describing the approach to a phase-slip event is derived. Detailed analysis of a phase slip using multiple time scale methods demonstrates different mechanisms governing the wavelength changing process at different stages.

  6. Study of cosmic ray effects on Artemia salina eggs during the Apollo 16 and 17 flights.

    PubMed

    Planel, H; Soleilhavoup, J P; Blanquet, Y; Kaiser, R

    1974-01-01

    We have used Artemia salina eggs, embedded in polyvinyl alcohol, to study the biological effects of heavy ions of cosmic rays. Each biological layer was sandwiched between track detectors. Hit eggs by heavy ions show a great inhibition of their developmental ability. A lower inhibition is observed for eggs that were flown but not hit. Simulation experiments are in progress to determine the factors responsible for inhibition of eggs that were not hit and to improve our knowledge of cellular damage induced by heavy ions.

  7. 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.

  8. Thermal effects on transverse domain wall dynamics in magnetic nanowires

    SciTech Connect

    Leliaert, J.; Van de Wiele, B.; Vandermeulen, J.; Coene, A.; Dupré, L.; Vansteenkiste, A.; Waeyenberge, B. Van; Laurson, L.; Durin, G.

    2015-05-18

    Magnetic domain walls are proposed as data carriers in future spintronic devices, whose reliability depends on a complete understanding of the domain wall motion. Applications based on an accurate positioning of domain walls are inevitably influenced by thermal fluctuations. In this letter, we present a micromagnetic study of the thermal effects on this motion. As spin-polarized currents are the most used driving mechanism for domain walls, we have included this in our analysis. Our results show that at finite temperatures, the domain wall velocity has a drift and diffusion component, which are in excellent agreement with the theoretical values obtained from a generalized 1D model. The drift and diffusion component are independent of each other in perfect nanowires, and the mean square displacement scales linearly with time and temperature.

  9. Light from cosmic strings

    SciTech Connect

    Steer, Daniele A.; Vachaspati, Tanmay

    2011-02-15

    The time-dependent metric of a cosmic string leads to an effective interaction between the string and photons--the ''gravitational Aharonov-Bohm'' effect--and causes cosmic strings to emit light. We evaluate the radiation of pairs of photons from cosmic strings and find that the emission from cusps, kinks and kink-kink collisions occurs with a flat spectrum at all frequencies up to the string scale. Further, cusps emit a beam of photons, kinks emit along a curve, and the emission at a kink-kink collision is in all directions. The emission of light from cosmic strings could provide an important new observational signature of cosmic strings that is within reach of current experiments for a range of string tensions.

  10. Comparative Analysis of Ionization Effect during Major Gles Due to Cosmic Rays

    NASA Astrophysics Data System (ADS)

    Mishev, Alexander; Velinov, Peter

    2016-07-01

    Several major ground level enhancements (GLEs) occurred during previous solar cycle 23. During the solar cycle 23, sixteen GLE events were observed with intensities ranging ~ 3 - 269% at the sea level. The first event occurred on 6 November 1997 (GLE 55) and the last event occurred on 13 December 2006 (GLE 70). Here we focus on major GLEs, namely on their ionization effect due to cosmic rays of galactic and solar origin and provide a comparative analysis. The solar energetic particles protons of MeV and greater energies cause an excess of ionization in the atmosphere. The ionization effect in the Earth atmosphere is obtained for various latitudes and altitudes in the atmosphere using solar proton energy spectra derived from ground based measurements with neutron monitors. The ion production is obtained using a numerical model for cosmic ray induced ionization, based on Monte Carlo simulations of atmospheric cascade ion the atmosphere of the Earth. Her we consider the GLE 70 on December of 13, 2006, which is among is among the strongest recorded events during solar cycle 23, even it occurred at quit solar activity conditions. We compare the ionization effect this event with Bastille day event (GLE 59). A quantitative comparison with the sequence of Halloween events (GLE 65-67) and the major event of 20 January 2005 (GLE 69) is carried out. We briefly discussed the results.

  11. The effects of cosmic particle radiation on pocket mice aboard Apollo XVII: VII. Cosmic ray particle dosimetry and trajectory tracing.

    PubMed

    Cruty, M R; Benton, E V; Turnbill, C E; Philpott, D E

    1975-04-01

    Five pocket mice (Perognathus longimembris) were flown on Apollo XVII, each with a solid-state (plastic) nuclear track detector implanted beneath its scalp. The subscalp detectors were sensitive to HZE cosmic ray particles with a LET larger than or equal to 0.15 million electron volts per micrometer (MeV/mjm). A critical aspect of the dosimetry of the experiment involved tracing individual particle trajectories through each mouse head from particle tracks registered in the individual subscalp detectors, thereby establishing a one-to-one correspondence between a trajectory location in the tissue and the presence or absence of a lesion. The other major aspect was the identification of each registered particle. An average of 16 particles with Z larger than or equal to 6 and 2.2 particles with Z larger than or equal to 20 were found per detector. The track density, 29 tracks/cm2, when adjusted for detection volume, was in agreement with the photographic emulsion data from an area dosimeter located next to the flight package.

  12. Cosmic bubble and domain wall instabilities III: the role of oscillons in three-dimensional bubble collisions

    SciTech Connect

    Bond, J. Richard; Braden, Jonathan; Mersini-Houghton, Laura E-mail: j.braden@ucl.ac.uk

    2015-09-01

    We study collisions between pairs of bubbles nucleated in an ambient false vacuum. For the first time, we include the effects of small initial (quantum) fluctuations around the instanton profiles describing the most likely initial bubble profile. Past studies of this problem neglect these fluctuations and work under the assumption that the collisions posess an exact SO(2,1) symmetry. We use three-dimensional lattice simulations to demonstrate that for double-well potentials, small initial perturbations to this symmetry can be amplified as the system evolves. Initially the amplification is well-described by linear perturbation theory around the SO(2,1) background, but the onset of strong nonlinearities amongst the fluctuations quickly leads to a drastic breaking of the original SO(2,1) symmetry and the production of oscillons in the collision region. We explore several single-field models, and we find it is hard to both realize inflation inside of a bubble and produce oscillons in a collision. Finally, we extend our results to a simple two-field model. The additional freedom allowed by the second field allows us to construct viable inflationary models that allow oscillon production in collisions. The breaking of the SO(2,1) symmetry allows for a new class of observational signatures from bubble collisions that do not posess azimuthal symmetry, including the production of gravitational waves which cannot be supported by an SO(2,1) spacetime.

  13. The effects of cosmic microwave background (CMB) temperature uncertainties on cosmological parameter estimation

    SciTech Connect

    Hamann, Jan; Wong, Yvonne Y Y E-mail: ywong@mppmu.mpg.de

    2008-03-15

    We estimate the effect of the experimental uncertainty in the measurement of the temperature of the cosmic microwave background (CMB) on the extraction of cosmological parameters from future CMB surveys. We find that even for an ideal experiment limited only by cosmic variance up to l=2500 for both the temperature and polarization measurements, the projected cosmological parameter errors are remarkably robust against the uncertainty of 1 mK in the firas CMB temperature monopole measurement. The maximum degradation in sensitivity is 20%, for the baryon density estimate, relative to the case in which the monopole is known infinitely well. While this degradation is acceptable, we note that reducing the uncertainty in the current temperature measurement by a factor of five will bring it down to {approx}1%. We also estimate the effect of the uncertainty in the dipole temperature measurement. Assuming the overall calibration of the data to be dominated by the dipole error of 0.2% from firas, the sensitivity degradation is insignificant and does not exceed 10% in any parameter direction.

  14. Effect of Primordial Black Holes on the Cosmic Microwave Background and Cosmological Parameter Estimates

    NASA Astrophysics Data System (ADS)

    Ricotti, Massimo; Ostriker, Jeremiah; Mack, Katherine

    2017-01-01

    We investigate the effect of nonevaporating primordial black holes (PBHs) on the ionization and thermal history of the universe. X-rays emitted by gas accretion onto PBHs modify the cosmic recombination history, producing measurable effects on the spectrum and anisotropies of the cosmic microwave background (CMB). Using the third-year WMAP data and COBE FIRAS data we improve existing upper limits on the abundance of PBHs with masses > 0 . 1 M⊙ by several orders of magnitude, thus ruling out PBHs in this mass range as a significant component of the dark matter. Fitting WMAP/Planck data with cosmological models that do not allow for nonstandard recombination histories, as produced by PBHs or other early energy sources, leads to underestimating the best-fit values of the amplitude of linear density fluctuations (σ8) and the scalar spectral index (ns). We find that a fraction > 0 . 1 % - 1 % of the dark matter in 30 M⊙ PBHs produces CMB spectral distortions at a level detectable by FIRAS. Therefore, even allowing for possible modeling uncertainties, future missions measuring CMB spectral distortions will detect the imprint of dark matter if it's composed of 30 M⊙ PBHs, as suggested to interpret recent LIGO results.

  15. The effect of cosmic web filaments on the properties of groups and their central galaxies

    NASA Astrophysics Data System (ADS)

    Poudel, A.; Heinämäki, P.; Tempel, E.; Einasto, M.; Lietzen, H.; Nurmi, P.

    2017-01-01

    Context. The nature versus nurture scenario in galaxy and group evolution is a long-standing problem not yet fully understood on cosmological scales. Aims: We study the properties of groups and their central galaxies in different large-scale environments defined by the luminosity density field and the cosmic web filaments. Methods: We use the luminosity density field constructed using 8 h-1 Mpc smoothing to characterize the large-scale environments. We use the Bisous model to extract the filamentary structures in different large-scale environments. We study the properties of galaxy groups as a function of their dynamical mass in different large-scale environments. Results: We find differences in the properties of central galaxies and their groups in and outside of filaments at fixed halo and large-scale environments. In high-density environments, the group mass function has higher number densities in filaments compared to that outside of filaments towards the massive end. The relation is the opposite in low-density environments. At fixed group mass and large-scale luminosity density, mass-to-light ratios show that groups in filaments are slightly more luminous than those outside of filaments. At fixed group mass and large-scale luminosity density, central galaxies in filaments have redder colors, higher stellar masses, and lower specific star formation rates than those outside of filaments. However, the differences in central galaxy and group properties in and outside of filaments are not clear in some group mass bins. We show that the differences in central galaxy properties are due to the higher abundances of elliptical galaxies in filaments. Conclusions: Filamentary structures in the cosmic web are not simply visual associations of galaxies, but rather play an important role in shaping the properties of groups and their central galaxies. The differences in central galaxy and group properties in and outside of cosmic web filaments are not simple effects related

  16. The effect of domain growth on spatial correlations

    NASA Astrophysics Data System (ADS)

    Ross, Robert J. H.; Yates, C. A.; Baker, R. E.

    2017-01-01

    Mathematical models describing cell movement and proliferation are important tools in developmental biology research. In this work we present methods to include the effects of domain growth on the evolution of spatial correlations between agent locations in a continuum approximation of a one-dimensional lattice-based model of cell motility and proliferation. This is important as the inclusion of spatial correlations in continuum models of cell motility and proliferation without domain growth has previously been shown to be essential for their accuracy in certain scenarios. We include the effect of spatial correlations by deriving a system of ordinary differential equations that describe the expected evolution of individual and pair density functions for agents on a growing domain. We then demonstrate how to simplify this system of ordinary differential equations by using an appropriate approximation. This simplification allows domain growth to be included in models describing the evolution of spatial correlations between agents in a tractable manner.

  17. Domain-General and Domain-Specific Creative-Thinking Tests: Effects of Gender and Item Content on Test Performance

    ERIC Educational Resources Information Center

    Hong, Eunsook; Peng, Yun; O'Neil, Harold F., Jr.; Wu, Junbin

    2013-01-01

    The study examined the effects of gender and item content of domain-general and domain-specific creative-thinking tests on four subscale scores of creative-thinking (fluency, flexibility, originality, and elaboration). Chinese tenth-grade students (234 males and 244 females) participated in the study. Domain-general creative thinking was measured…

  18. Systematic Effects in Polarizing Fourier Transform Spectrometers for Cosmic Microwave Background Observations

    NASA Astrophysics Data System (ADS)

    Nagler, Peter C.; Fixsen, Dale J.; Kogut, Alan; Tucker, Gregory S.

    2015-11-01

    The detection of the primordial B-mode polarization signal of the cosmic microwave background (CMB) would provide evidence for inflation. Yet as has become increasingly clear, the detection of a such a faint signal requires an instrument with both wide frequency coverage to reject foregrounds and excellent control over instrumental systematic effects. Using a polarizing Fourier transform spectrometer (FTS) for CMB observations meets both of these requirements. In this work, we present an analysis of instrumental systematic effects in polarizing FTSs, using the Primordial Inflation Explorer (PIXIE) as a worked example. We analytically solve for the most important systematic effects inherent to the FTS—emissive optical components, misaligned optical components, sampling and phase errors, and spin synchronous effects—and demonstrate that residual systematic error terms after corrections will all be at the sub-nK level, well below the predicted 100 nK B-mode signal.

  19. Effects of Nuclear Cross Sections at Different Energies on the Radiation Hazard from Galactic Cosmic Rays

    NASA Technical Reports Server (NTRS)

    Lin, Z. W.; Adams, J. H., Jr.

    2006-01-01

    The radiation hazard for astronauts from galactic cosmic rays is a major obstacle in long duration human space explorations. Space radiation transport codes have been developed to calculate radiation environment on missions to the Moon, Mars or beyond. We have studied how uncertainties in fragmentation cross sections at different energies affect the accuracy of predictions from such radiation transport. We find that, in deep space, cross sections between 0.3 and 0.85 GeV/u usually have the largest effect on dose-equivalent behind shielding in solar minimum GCR environments, and cross sections between 0.85 and 1.2 GeV/u have the largest effect in solar maximum GCR environments. At the International Space Station, cross sections at higher energies have the largest effect due to the geomagnetic cutoff.

  20. SYSTEMATIC EFFECTS IN POLARIZING FOURIER TRANSFORM SPECTROMETERS FOR COSMIC MICROWAVE BACKGROUND OBSERVATIONS

    SciTech Connect

    Nagler, Peter C.; Tucker, Gregory S.; Fixsen, Dale J.; Kogut, Alan

    2015-11-15

    The detection of the primordial B-mode polarization signal of the cosmic microwave background (CMB) would provide evidence for inflation. Yet as has become increasingly clear, the detection of a such a faint signal requires an instrument with both wide frequency coverage to reject foregrounds and excellent control over instrumental systematic effects. Using a polarizing Fourier transform spectrometer (FTS) for CMB observations meets both of these requirements. In this work, we present an analysis of instrumental systematic effects in polarizing FTSs, using the Primordial Inflation Explorer (PIXIE) as a worked example. We analytically solve for the most important systematic effects inherent to the FTS—emissive optical components, misaligned optical components, sampling and phase errors, and spin synchronous effects—and demonstrate that residual systematic error terms after corrections will all be at the sub-nK level, well below the predicted 100 nK B-mode signal.

  1. Cytogenetic effects of heavy charged particles of galactic cosmic radiation in experiments aboard Cosmos-1129 biosatellite

    SciTech Connect

    Nevzgodina, L.V.; Maksimova, Y.N.

    1982-08-01

    An experiment was carried out on lettuce (Lactuca sativa) seeds flown in a biocontainer equipped with plastic detectors to record heavy charged particles (HCP). The purpose of the experiment was to determine the yield of aberrant cells as a result of irradiation, and to identify this effect as a function of HCP topography in the seed. The cytogenetic examination of flight seedlings revealed a significant difference between the seeds which were hit with HCP and those that remained intact. This indicates a significant contribution of the heavy component of galactic cosmic radiation into the radiobiological effect. The relationship between the radiobiological effect and the HCP topography in the seed was established: zones of the root and stem meristem proved to be the most sensitive targets.

  2. Effective Domain Partitioning for Multi-Clock Domain IP Core Wrapper Design under Power Constraints

    NASA Astrophysics Data System (ADS)

    Yu, Thomas Edison; Yoneda, Tomokazu; Zhao, Danella; Fujiwara, Hideo

    The rapid advancement of VLSI technology has made it possible for chip designers and manufacturers to embed the components of a whole system onto a single chip, called System-on-Chip or SoC. SoCs make use of pre-designed modules, called IP-cores, which provide faster design time and quicker time-to-market. Furthermore, SoCs that operate at multiple clock domains and very low power requirements are being utilized in the latest communications, networking and signal processing devices. As a result, the testing of SoCs and multi-clock domain embedded cores under power constraints has been rapidly gaining importance. In this research, a novel method for designing power-aware test wrappers for embedded cores with multiple clock domains is presented. By effectively partitioning the various clock domains, we are able to increase the solution space of possible test schedules for the core. Since previous methods were limited to concurrently testing all the clock domains, we effectively remove this limitation by making use of bandwidth conversion, multiple shift frequencies and properly gating the clock signals to control the shift activity of various core logic elements. The combination of the above techniques gains us greater flexibility when determining an optimal test schedule under very tight power constraints. Furthermore, since it is computationally intensive to search the entire expanded solution space for the possible test schedules, we propose a heuristic 3-D bin packing algorithm to determine the optimal wrapper architecture and test schedule while minimizing the test time under power and bandwidth constraints.

  3. Surface effect on domain wall width in ferroelectrics

    SciTech Connect

    Eliseev, Eugene A.; Morozovska, Anna N.; Kalinin, Sergei V.; Li, Yulan; Shen, Jie; Glinchuk, Maya D.; Chen , L.Q.; Gopalan, Venkatraman

    2009-10-15

    We study the effect of the depolarization field on a domain wall structure near the surface of a ferroelectric. Since in real situation bound and screening charges form an electric double layer, the breaking of this layer by the domain wall induces stray depolarization field, which in turn changes the domain wall structure. Power law decay of the stray field results in the power law of polarization saturation near the surface, as compared to exponential saturation in the bulk. Obtained results predict that the surface broadening of ferroelectric domain walls appeared near Curie temperature as well as describe domain wall depth profile in weak ferroelectrics. We qualitatively describe extra-broad domain walls near LiNbO3 and LiTaO3 surfaces observed experimentally at room temperature, which probably originate at high temperatures but did not fully relax their width with temperature decrease allowing for lattice pinning and defect centers. Thus results have broad implication for fundamental issues such as maximal information storage density in ferroelectric data storage, domain wall pinning mechanisms at surfaces and interfaces, and nucleation dynamics.

  4. Initial state effects on the cosmic microwave background and trans-Planckian physics

    NASA Astrophysics Data System (ADS)

    Goldstein, Kevin; Lowe, David A.

    2003-03-01

    There exists a one complex parameter family of de Sitter invariant vacua, known as α vacua. In the context of slow roll inflation, we show that all but the Bunch-Davies vacuum generates unacceptable production of high energy particles at the end of inflation. As a simple model for the effects of trans-Planckian physics, we go on to consider non de Sitter invariant vacua obtained by patching modes in the Bunch-Davies vacuum above some momentum scale Mc, with modes in an α vacuum below Mc. Choosing Mc near the Planck scale MPl, we find acceptable levels of hard particle production, and corrections to the cosmic microwave perturbations at the level of HMPl/M2c, where H is the Hubble parameter during inflation. More general initial states of this type with H≪Mc≪MPl can give corrections to the spectrum of cosmic microwave background perturbations at order 1. The parameter characterizing the α vacuum during inflation is a new cosmological observable.

  5. Probing the physics and history of cosmic reionization with the Sunyaev-Zel'dovich effect

    NASA Astrophysics Data System (ADS)

    Colafrancesco, S.; Marchegiani, P.; Emritte, M. S.

    2016-10-01

    Context. The evolution of the Universe during the dark ages (DA) and the epoch of reonization (EoR) marks an important transition in the history of the Universe but it is not yet fully understood. Aims: We study here an alternative technique to probe the DA and EoR that makes use of the Comptonization of the CMB spectrum modified by physical effects occurring during this epoch related to the emergence of the 21-cm radiation background. Inverse Compton scattering of 21-cm photon background by thermal and non-thermal electrons residing in the atmospheres of cosmic structures like galaxy clusters, radiogalaxy lobes and galaxy halos, produces a specific form of Sunyaev-Zel'dovich effect (SZE) that we refer to as SZE-21 cm. Methods: We derived the SZE-21 cm in a general relativistic approach, which is required to describe the correct spectral features of this astrophysical effect. We calculated the spectral features of the thermal and non-thermal SZE-21 cm in galaxy clusters and in radiogalaxy lobes, and their dependence on the history of physical mechanisms occurring during the DA and EoR. We studied how the spectral shape of the SZE-21 cm can be used to establish the global features in the mean 21-cm spectrum generated during and prior to the EoR, and how it depends on the properties of the (thermal and non-thermal) plasma in cosmic structures. Results: We found that the thermal and non-thermal SZE-21 cm have peculiar spectral shapes that allow to investigate the physics and history of the EoR and DA. Its spectrum depends on the gas temperature (for the thermal SZE-21 cm) and on the electrons minimum momentum (for the non-thermal SZE-21 cm). The global SZE-21 cm signal can be detected (in ~ 1000 h) by SKA1-low in the frequency range ν ≳ 75-90 MHz, for clusters in the temperature range 5 to 20 keV, and the difference between the SZE-21 cm and the standard SZE can be detected by SKA1 or SKA2 at frequencies depending on the background model and the cluster temperature

  6. Galactic cosmic rays - atmosphere clouds effect and bifurcation model of the Earth global climate

    NASA Astrophysics Data System (ADS)

    Glushkov, Alexander

    The possible physical linkage between the cosmic rays, atmosphere cloud and indirect aerosol effects is discussed using analysis of first indirect aerosol effect (Twomey effect) and its experimental representation as the dependence of mean cloud droplet effective radius versus aerosol index defining the column aerosol number. It is shown that the main kinetic equation of Earth climate energy-balance model [1] is described by the bifurcation equation (relative to the Earth surface temperature) in the form of fold catastrophe with two controlling parameters defining the variations of insolation and Earth magnetic field (or cosmic rays intensity in the atmosphere) respectively. The results of comparative analysis on the time-dependent solution (time series of global paleotemperature ) of Earth climate energy-balance model taking into account nontrivial role of galactic cosmic rays and the known experimental data on the palaeotemperature from the EPICA Dome C and Vostok ice core are pre-sented. It is discussed the sin-earth mechanism of arising the abnormal temperature breaks which are observed in the EPICA Dome C and Vostok experiments. It has been found its link with the ‘order-chaos' transitions in evolution of the convection in the Earth liquid core which are responsible for mechanism of arising inversions of the magnetic field of the Earth. It should be noted a stabilization role of the slow nuclear burning [1] georeactor with power 30 TW) on the boundary of the liquid and solid phases of the Earth's core in evolution of convection in the Earth liquid core and magnetic field. In the bifurcation model (i) the possibility of abrupt glacial climate changes analogous to the Dansgaard-Oeschger events due to stochastic resonance is theoretically argued, (ii) the concept of the climatic sensitivity of water (vapour and liquid) in the atmosphere is introduced. This concept reveals the property of temperature instability in a form of so-called hysteresis loop. It is

  7. Domain Wall Motion by the Magnonic Spin Seebeck Effect

    NASA Astrophysics Data System (ADS)

    Hinzke, D.; Nowak, U.

    2011-07-01

    The recently discovered spin Seebeck effect refers to a spin current induced by a temperature gradient in a ferromagnetic material. It combines spin degrees of freedom with caloric properties, opening the door for the invention of new, spin caloritronic devices. Using spin model simulations as well as an innovative, multiscale micromagnetic framework we show that magnonic spin currents caused by temperature gradients lead to spin transfer torque effects, which can drag a domain wall in a ferromagnetic nanostructure towards the hotter part of the wire. This effect opens new perspectives for the control and manipulation of domain structures.

  8. Domain wall motion by the magnonic spin Seebeck effect.

    PubMed

    Hinzke, D; Nowak, U

    2011-07-08

    The recently discovered spin Seebeck effect refers to a spin current induced by a temperature gradient in a ferromagnetic material. It combines spin degrees of freedom with caloric properties, opening the door for the invention of new, spin caloritronic devices. Using spin model simulations as well as an innovative, multiscale micromagnetic framework we show that magnonic spin currents caused by temperature gradients lead to spin transfer torque effects, which can drag a domain wall in a ferromagnetic nanostructure towards the hotter part of the wire. This effect opens new perspectives for the control and manipulation of domain structures.

  9. Cosmic-Ray-Induced Ship-Effect Neutron Measurements and Implications for Cargo Scanning at Borders

    SciTech Connect

    Kouzes, Richard T.; Ely, James H.; Seifert, Allen; Siciliano, Edward R.; Weier, Dennis R.; Windsor, Lindsay K.; Woodring, Mitchell L.; Borgardt, James D.; Buckley, Elise D.; Flumerfelt, Eric L.; Oliveri, Anna F.; Salvitti, Matthew

    2008-03-11

    Neutron measurements are used as part of the interdiction process for illicit nuclear materials at border crossings. Even though the natural neutron background is small, its variation can impact the sensitivity of detection systems. The natural background of neutrons that is observed in monitoring instruments arises almost entirely from cosmic ray induced cascades in the atmosphere and the surrounding environment. One significant source of variation in the observed neutron background is produced by the “ship effect” in large quantities of cargo that transit past detection instruments. This paper reports on results from measurements with typical monitoring equipment of ship effect neutrons in various materials. One new result is the “neutron shadow shielding” effect seen with some low neutron density materials.

  10. Probing the effective number of neutrino species with the cosmic microwave background

    SciTech Connect

    Ichikawa, Kazuhide; Sekiguchi, Toyokazu; Takahashi, Tomo

    2008-10-15

    We discuss how much we can probe the effective number of neutrino species N{sub {nu}} with the cosmic microwave background alone. Using the data of the WMAP, ACBAR, CBI, and BOOMERANG experiments, we obtain a constraint on the effective number of neutrino species as 0.96

  11. Bistability of ferroelectric domain walls: Morphotropic boundary and strain effects

    NASA Astrophysics Data System (ADS)

    Yudin, P. V.; Tagantsev, A. K.; Setter, N.

    2013-07-01

    The internal structure of neutral 180∘ domain walls in perovskite-type ferroelectrics is studied in terms of Landau theory taking into account electromechanical coupling. The study is focused on the wall bistability, a factor of potential interest for information storage. A strong impact of elastic effects on the wall structure is demonstrated. It is shown that the conclusion derived earlier by Houchmandzadeh [J. Phys.: Condens. MatterJCOMEL0953-898410.1088/0953-8984/3/27/009 3, 5163 (1991)], neglecting the electrostictive coupling, that all the domain walls near the boundary between two ordered phases become bistable may not hold due to the elastic effects. Criteria for domain-wall bistability are formulated in terms of the materials thermodynamic properties and the wall orientation. The obtained general results are applied to the analysis of bistability of 180∘ domain walls in Pb(Zrc,Ti1-c)O3 near the tetragonal-rhombohedral morphotropic boundary. It is shown that, on the tetragonal side, the electrostrictive interaction suppresses the wall bistability that was predicted in terms of the theory neglecting the elastic effects. On the rhombohedral side, the domain walls are found bistable or not depending on the anisotropy of the correlation energy, the information on which is not presently available. It is also shown that, in the rhombohedral phase, the anisotropy of the correlation energy results in appearance of additional polarization component in the plane of the wall.

  12. The effects of magnetic field modifications on the solar modulation of cosmic rays with a SDE-based model

    NASA Astrophysics Data System (ADS)

    Raath, J. L.; Potgieter, M. S.; Strauss, R. D.; Kopp, A.

    2016-05-01

    A numerical model for the solar modulation of cosmic rays, based on the solution of a set of stochastic differential equations (SDEs), is used to illustrate the effects of modifying the heliospheric magnetic field, particularly in the polar regions of the heliosphere. SDE-based models are well suited for such studies so that new insights are gained. To this end, the differences in the modulation brought about by each of three choices for the heliospheric magnetic field, i.e. the unmodified Parker field, the Smith-Bieber modified field, and the Jokipii-Kóta modified field, are studied as typical well-known cases. It is illustrated that although both these modifications change the Parker field satisfactorily in the polar regions of the heliosphere, the Smith-Bieber modification is more effective in reducing cosmic ray drift effects in these regions. The features of these two modifications, as well as the effects on the solar modulation of cosmic rays, are illustrated qualitatively and quantitatively. In particular, it is shown how the Smith-Bieber modified field is applied in a cosmic ray modulation model to reproduce observational proton spectra from the PAMELA mission during the solar minimum of 2006-2009. These SDE-based results are compared with those obtained in previous studies of this unusual solar minimum activity period and found to be in good qualitative agreement.

  13. Cosmic superstrings.

    PubMed

    Sakellariadou, Mairi

    2008-08-28

    Cosmic superstrings are expected to be formed at the end of brane inflation, within the context of brane-world cosmological models inspired from string theory. By studying the properties of cosmic superstring networks and comparing their phenomenological consequences against observational data, we aim to pin down the successful and natural inflationary model and get an insight into the stringy description of our Universe.

  14. Geomagnetic modulation of clouds effects in the Southern Hemisphere Magnetic Anomaly through lower atmosphere cosmic ray effects

    NASA Astrophysics Data System (ADS)

    Vieira, Luis Eduardo Antunes; da Silva, Ligia Alves

    2006-07-01

    The study of the physical processes that drive the variability of the Earth's climate system is one of the most fascinating and challenging topics of research today. Perhaps the largest uncertainties in our ability to predict climate change are the cloud formation process and the interaction of clouds with radiation. Here we show that in the southern Pacific Ocean cloud effects on the net radiative flux in the atmosphere are related to the intensity of the Earth's magnetic field through lower atmosphere cosmic ray effects. In the inner region of the Southern Hemisphere Magnetic Anomaly (SHMA) it is observed a cooling effect of approximately 18 W/m2 while in the outer region it is observed a heating effect of approximately 20 W/m2. The variability in the inner region of the SHMA of the net radiative flux is correlated to galactic cosmic rays (GCRs) flux observed in Huancayo, Peru (r = 0.73). It is also observed in the correlation map that the correlation increases in the inner region of the SHMA. The geomagnetic modulation of cloud effects in the net radiative flux in the atmosphere in the SHMA is, therefore, unambiguously due to GCRs and/or highly energetic solar proton particles effects.

  15. Soil water content determination with cosmic-ray neutron sensor: Correcting aboveground hydrogen effects with thermal/fast neutron ratio

    NASA Astrophysics Data System (ADS)

    Tian, Zhengchao; Li, Zizhong; Liu, Gang; Li, Baoguo; Ren, Tusheng

    2016-09-01

    The cosmic-ray neutron sensor (CRNS), which estimates field scale soil water content, bridges the gap between point measurement and remote sensing. The accuracy of CRNS measurements, however, is affected by additional hydrogen pools (e.g., vegetation, snow, and rainfall interception). The objectives of this study are to: (i) evaluate the accuracy of CRNS estimates in a farmland system using depth and horizontal weighted point measurements, (ii) introduce a novel method for estimating the amounts of hydrogen from biomass and snow cover in CRNS data, and (iii) propose a simple approach for correcting the influences of aboveground hydrogen pool (expressed as aboveground water equivalent, AWE) on CRNS measurements. A field experiment was conducted in northeast China to compare soil water content results from CRNS to in-situ data with time domain reflectometry (TDR) and neutron probe (NP) in the 0-40 cm soil layers. The biomass water equivalent (BWE) and snow water equivalent (SWE) were observed to have separate linear relationships with the thermal/fast neutron ratio, and the dynamics of BWE and SWE were estimated correctly in the crop seasons and snow-covered seasons, respectively. A simple approach, which considered the AWE, AWE at calibration, and the effective measurement depth of CRNS, was introduced to correct the errors caused by BWE and SWE. After correction, the correlation coefficients between soil water contents determined by CRNS and TDR were 0.79 and 0.77 during the 2014 and 2015 crop seasons, respectively, and CRNS measurements had RMSEs of 0.028, 0.030, and 0.039 m3 m-3 in the 2014 and 2015 crop seasons and the snow-covered seasons, respectively. The experimental results also indicated that the accuracies of CRNS estimated BWE and SWE were affected by the distributions of aboveground hydrogen pools, which were related to the height of the CRNS device above ground surface.

  16. Viscosity and inertia in cosmic-ray transport - Effects of an average magnetic field

    NASA Technical Reports Server (NTRS)

    Williams, L. L.; Jokipii, J. R.

    1991-01-01

    A generalized transport equation is introduced which describes the transport and propagation of cosmic rays in a magnetized, collisionless medium. The equation is valid if the cosmic-ray distribution function is nearly isotropic in momentum, if the ratio of fluid speed to fluid-flow particle speed is small, and if the ratio of collision time to time for change in the macroscopic flow is small. Five independent cosmic-ray viscosity coefficients are found, and the ralationship of this viscosity to particle orbits in a magnetic field is presented.

  17. Regional and temporal variability of solar activity and galactic cosmic ray effects on the lower atmosphere circulation

    NASA Astrophysics Data System (ADS)

    Veretenenko, S.; Ogurtsov, M.

    2012-02-01

    In this work we studied the spatial and temporal structure of long-term effects of solar activity (SA) and galactic cosmic ray (GCR) variations on the lower atmosphere circulation as well as possible reasons for the peculiarities of this structure. The study revealed a strong latitudinal and regional dependence of SA/GCR effects on pressure variations in the lower troposphere which seems to be determined by specific features of baric systems formed in different regions. The temporal structure of SA/GCR effects on the troposphere circulation at high and middle latitudes is characterized by a roughly 60-year periodicity which is apparently due to the epochs of the large-scale atmospheric circulation. It is suggested that a possible mechanism of long-term effects of solar activity and cosmic ray variations on the troposphere circulation involves changes in the evolution of the polar vortex in the stratosphere of high latitudes, as well as planetary frontal zones.

  18. MAXIMUM LIKELIHOOD FOREGROUND CLEANING FOR COSMIC MICROWAVE BACKGROUND POLARIMETERS IN THE PRESENCE OF SYSTEMATIC EFFECTS

    SciTech Connect

    Bao, C.; Hanany, S.; Baccigalupi, C.; Gold, B.; Jaffe, A.; Stompor, R.

    2016-03-01

    We extend a general maximum likelihood foreground estimation for cosmic microwave background (CMB) polarization data to include estimation of instrumental systematic effects. We focus on two particular effects: frequency band measurement uncertainty and instrumentally induced frequency dependent polarization rotation. We assess the bias induced on the estimation of the B-mode polarization signal by these two systematic effects in the presence of instrumental noise and uncertainties in the polarization and spectral index of Galactic dust. Degeneracies between uncertainties in the band and polarization angle calibration measurements and in the dust spectral index and polarization increase the uncertainty in the extracted CMB B-mode power, and may give rise to a biased estimate. We provide a quantitative assessment of the potential bias and increased uncertainty in an example experimental configuration. For example, we find that with 10% polarized dust, a tensor to scalar ratio of r = 0.05, and the instrumental configuration of the E and B experiment balloon payload, the estimated CMB B-mode power spectrum is recovered without bias when the frequency band measurement has 5% uncertainty or less, and the polarization angle calibration has an uncertainty of up to 4°.

  19. PLASMA EFFECTS ON EXTRAGALACTIC ULTRAHIGH-ENERGY COSMIC-RAY HADRON BEAMS IN COSMIC VOIDS. II. KINETIC INSTABILITY OF PARALLEL ELECTROSTATIC WAVES

    SciTech Connect

    Krakau, S.; Schlickeiser, R. E-mail: rsch@tp4.rub.de

    2016-02-20

    The linear instability of an ultrarelativistic hadron beam in the unmagnetized intergalactic medium (IGM) is investigated with respect to the excitation of parallel electrostatic and electromagnetic fluctuations. This analysis is important for the propagation of extragalactic ultrarelativistic cosmic rays from their distant sources to Earth. As opposed to the previous paper, we calculate the minimum instability growth time for Lorentz-distributed cosmic rays which traverse the hot IGM. The growth times are orders of magnitude higher than the cosmic-ray propagation time in the IGM. Since the backreaction of the generated plasma fluctuations (plateauing) lasts longer than the propagation time, the cosmic-ray hadron beam can propagate to the Earth without losing a significant amount of energy to electrostatic turbulence.

  20. Cosmic strings and galaxy formation

    NASA Technical Reports Server (NTRS)

    Bertschinger, Edmund

    1989-01-01

    The cosmogonical model proposed by Zel'dovich and Vilenkin (1981), in which superconducting cosmic strings act as seeds for the origin of structure in the universe, is discussed, summarizing the results of recent theoretical investigations. Consideration is given to the formation of cosmic strings, the microscopic structure of strings, gravitational effects, cosmic string evolution, and the formation of galaxies and large-scale structure. Simulation results are presented in graphs, and several outstanding issues are listed and briefly characterized.

  1. Effects of Nuclear Cross Sections at Different Energies on Space Radiation Exposure from Galactic Cosmic Rays

    NASA Technical Reports Server (NTRS)

    Li, Zi-Wei; Adams, James H., Jr.

    2007-01-01

    Space radiation from galactic cosmic rays (GCR) is a major hazard to space crews, especially in long duration human space explorations. For this reason, they will be protected by radiation shielding that fragments the GCR heavy ions. Here we investigate how sensitive the crew's radiation exposure is to nuclear fragmentation cross sections at different energies. We find that in deep space cross sections between about 0.2 and 1.2 GeV/u have the strongest effect on dose equivalent behind shielding in solar minimum GCR environments, and cross sections between about 0.6 and 1.7 GeV/u are the most important at solar maximum'. On the other hand, at the location of the International Space Station, cross sections at_higher -energies, between about 0.6 and 1.7 GeV /u at solar minimum and between about 1.7 and 3.4 GeV/u'at,solar maximum, are the most important This is. due-to the average geomagnetic cutoff for the ISS orbit. We also show the effect of uncertainties in the fragmentation cross sections on the elemental energy spectra behind shielding. These results help to focus the studies of fragmentation cross sections on the proper energy range in order to improve our predictions of crew exposures.

  2. The effect of hot gas in early-type galaxies on the cosmic microwave background

    NASA Technical Reports Server (NTRS)

    Trester, Jeffrey J.; Canizares, Claude R.

    1989-01-01

    The effects on the cosmic microwave background which are due to Compton scattering by the hot gas contained in early-type galaxies (the Sunyaev-Zeldovich effect) are computed. Using the known properties of the gas deduced from X-ray observations, it is found that the fractional attenuation DeltaT/T at the center of a gas-rich galaxy is likely to be less than 10 to the -5th, which is just below current limits of detectability. A distribution function is derived for the attenuation which is due to a population of early-type galaxies out to some redshift and the expected rms fluctuations in the background on subarcmin scales are computed. These fluctuations are comparable to those intrinsic to the microwave background in the 'cold dark matter' scenario on these angular scales, but they fall orders of magnitude below the detection limits and below the level of fluctuations expected from nonlinear density perturbations at the epoch of galaxy formation.

  3. The effect of cosmic rays on biological systems - an investigation during GLE events

    NASA Astrophysics Data System (ADS)

    Belisheva, N. K.; Lammer, H.; Biernat, H. K.; Vashenuyk, E. V.

    2012-01-01

    In this study, first direct and circumstantial evidences of the effects of cosmic rays (CR) on biological systems are presented. A direct evidence of biological effects of CR is demonstrated in experiments with three cellular lines growing in culture during three events of Ground Level Enhancement (GLEs) in the neutron count rate detected by ground-based neutron monitor in October 1989. Various phenomena associated with DNA lesion on the cellular level demonstrate coherent dynamics of radiation effects in all cellular lines coincident with the time of arrival of high-energy solar particles to the near-Earth space and with the main peak in GLE. These results were obtained in the course of six separate experiments, with partial overlapping of the time of previous and subsequent experiments, which started and finished in the quiet period of solar activity (SA). A significant difference between the values of multinuclear cells in all cellular lines in the quiet period and during GLE events indicates that the cause of radiation effects in the cell cultures is an exposure of cells to the secondary solar CR near the Earth's surface. The circumstantial evidence was obtained by statistical analysis of cases of congenital malformations (CM) at two sites in the Murmansk region. The number of cases of all classes of CM reveals a significant correlation with the number of GLE events. The number of cases of CM with pronounced chromosomal abnormalities clearly correlates with the GLE events that occurred a year before the birth of a child. We have found a significant correlation between modulations of the water properties and daily background variations of CR intensity. We believe that the effects of CR on biological systems can be also mediated by fluctuations in water properties, considered as one of possible mechanisms controlling the effects of CRs on biological systems.

  4. Cosmic ray snow effect in different multiplicities according to Emilio Segre Observatory NM hourly data

    NASA Astrophysics Data System (ADS)

    Dorman, L. I.; Iucci, N.; Mavromichalaki, H.; Pustilnik, L. A.; Sternlieb, A.; Villoresi, G.; Zukerman, I. G.

    2001-08-01

    On the basis of cosmic ray hourly data obtained by NM of Emilio Segre' Observatory (hight 2025 m above s.l., cut-off rigidity for vertical direction 10.8 GV) we determine the snow effect in CR for total neutron intensity and for multiplicities m?1, m?2, m?3, m?4, m?5, m?6, m?7, and m?8, as well as for m=1, m=2, m=3, m=4, m=5, m=6, and m=7. For comparison and excluding primary CR variations we use also hourly data on neutron multiplicities obtained by NM of University "Roma Tre" (about sea level,cutoff rigidity 6.7 GV) and hourly data of total intensity of NM of the University of Athens (about sea level, cut-off rigidity 8.7 GV). In this paper we will analize effects of snow in periods from 4 January 2000 to 15 April 2000 (with maximal absorption effect about 5%) and from 21 December 2000 up to 31 March 2001 with maximal effect 13% in the total neutron intensity. We use the periods without snow to determine regeression coefficients between primary CR variations observed by NM of Emilio Segre' Observatory, by Rome NM and Athens NM. On the basis of obtained results we develop a method to correct data on snow effect by using several NM hourly data.On the basis of our data we estimate the accuracy with what can be made correction of NM data of stations where the snow effect can be important.

  5. ANALYSIS OF MAGNETOROTATIONAL INSTABILITY WITH THE EFFECT OF COSMIC-RAY DIFFUSION

    SciTech Connect

    Kuwabara, Takuhito; Ko, Chung-Ming E-mail: cmko@astro.ncu.edu.tw

    2015-01-10

    We present the results obtained from the linear stability analysis and 2.5 dimensional magnetohydrodynamic (MHD) simulations of magnetorotational instability (MRI), including the effects of cosmic rays (CRs). We took into account the CR diffusion along the magnetic field but neglected the cross-field-line diffusion. Two models are considered in this paper: the shearing box model and differentially rotating cylinder model. We studied how MRI is affected by the initial CR pressure (i.e., energy) distribution. In the shearing box model, the initial state is uniform distribution. Linear analysis shows that the growth rate of MRI does not depend on the value of the CR diffusion coefficient. In the differentially rotating cylinder model, the initial state is a constant angular momentum polytropic disk threaded by a weak uniform vertical magnetic field. Linear analysis shows that the growth rate of MRI becomes larger if the CR diffusion coefficient is larger. Both results are confirmed by MHD simulations. The MHD simulation results show that the outward movement of matter by the growth of MRI is not impeded by the CR pressure gradient, and the centrifugal force that acts on the concentrated matter becomes larger. Consequently, the growth rate of MRI is increased. On the other hand, if the initial CR pressure is uniform, then the growth rate of the MRI barely depends on the value of the CR diffusion coefficient.

  6. ON THE EFFECT OF THE COSMIC MICROWAVE BACKGROUND IN HIGH-REDSHIFT (SUB-)MILLIMETER OBSERVATIONS

    SciTech Connect

    Da Cunha, Elisabete; Groves, Brent; Walter, Fabian; Decarli, Roberto; Rix, Hans-Walter; Weiss, Axel; Bertoldi, Frank; Carilli, Chris; Daddi, Emanuele; Sargent, Mark; Maiolino, Roberto; Riechers, Dominik; Smail, Ian

    2013-03-20

    Modern (sub-)millimeter interferometers enable the measurement of the cool gas and dust emission of high-redshift galaxies (z > 5). However, at these redshifts the cosmic microwave background (CMB) temperature is higher, approaching, and even exceeding, the temperature of cold dust and molecular gas observed in the local universe. In this paper, we discuss the impact of the warmer CMB on (sub-)millimeter observations of high-redshift galaxies. The CMB affects the observed (sub-)millimeter dust continuum and the line emission (e.g., carbon monoxide, CO) in two ways: (1) it provides an additional source of (both dust and gas) heating and (2) it is a non-negligible background against which the line and continuum emission are measured. We show that these two competing processes affect the way we interpret the dust and gas properties of high-redshift galaxies using spectral energy distribution models. We quantify these effects and provide correction factors to compute what fraction of the intrinsic dust (and line) emission can be detected against the CMB as a function of frequency, redshift, and temperature. We discuss implications on the derived properties of high-redshift galaxies from (sub-)millimeter data. Specifically, the inferred dust and molecular gas masses can be severely underestimated for cold systems if the impact of the CMB is not properly taken into account.

  7. Heliospheric current sheet and effects of its interaction with solar cosmic rays

    NASA Astrophysics Data System (ADS)

    Malova, H. V.; Popov, V. Yu.; Grigorenko, E. E.; Dunko, A. V.; Petrukovich, A. A.

    2016-08-01

    The effects of interaction of solar cosmic rays (SCRs) with the heliospheric current sheet (HCS) in the solar wind are analyzed. A self-consistent kinetic model of the HCS is developed in which ions with quasiadiabatic dynamics can present. The HCS is considered an equilibrium embedded current structure in which two main plasma species with different temperatures (the low-energy background plasma of the solar wind and the higher energy SCR component) contribute to the current. The obtained results are verified by comparing with the results of numerical simulations based on solving equations of motion by the particle tracing method in the given HCS magnetic field with allowance for SCR particles. It is shown that the HCS is a relatively thin multiscale current configuration embedded in a thicker plasma layer. In this case, as a rule, the shear (tangential to the sheet current) component of the magnetic field is present in the HCS. Taking into account high-energy SCR particles in the HCS can lead to a change of its configuration and the formation of a multiscale embedded structure. Parametric family of solutions is considered in which the current balance in the HCS is provided at different SCR temperatures and different densities of the high-energy plasma. The SCR densities are determined at which an appreciable (detectable by satellites) HCS thickening can occur. Possible applications of this modeling to explain experimental observations are discussed.

  8. Effects of Cutoffs on Galactic Cosmic-Ray Interactions in Solar-System Matter

    NASA Technical Reports Server (NTRS)

    Kim, K. J.; Reedy, R. C.; Masarik, J.

    2005-01-01

    The energetic particles in the galactic cosmic rays (GCR) induce many interactions in a variety of solar-system matter. Cosmogenic nuclides are used to study the histories of meteorites and lunar samples. Gamma rays and neutrons are used to map the compositions of planetary surfaces, such as Mars, the Moon, and asteroids. In almost all of these cases, the spectra of incident GCR particles are fairly similar, with only some modulation by the Sun over an 11-year cycle. Strong magnetic fields can seriously affect the energy spectrum of GCR particles hitting the surface of objects inside the magnetic fields. The Earth s geomagnetic field is strong enough that only GCR particles with magnetic rigidities above approx. 17 GV (a proton energy of approx. 17 GeV) reach the atmosphere over certain regions near the equator. This effect of removing lower-energy GCR particles is called a cutoff. The jovian magnetic fields are so strong that the fluxes of GCR particles hitting the 4 large Galilean satellites are similarly affected. The cutoff at Europa is estimated to be similar to or a little higher than at the Earth s equator.

  9. Modeling and Experimental Study of Forbush Effects of Galactic Cosmic Rays

    NASA Astrophysics Data System (ADS)

    Alania, Michael V.; Szabelski, J.; Wawrzynczak, A.

    2003-07-01

    temporal changes of the rigidity spectrum of the sporadic and recurrent Forbush effects of galactic cosmic rays (GCR) have been studied using neutron monitors data. An attempt to find a relationship between the rigidity spectrum exponent γ of the Forbush effects (δD/D(R) ∝ R-γ , where R is the rigidity of GCR particles) and an exponent ν of the power spectral density (PSD) of the fluctuations of the strength of the interplanetary magnetic field (IMF) (PSD ∝ f-ν , where f is the frequency) has been made. EXPERIMENTAL DATA AND METHOD OF INVESTIGATION. An attempt to find a relationship between the rigidity spectrum exponent γ of the Forbush effects [1] (δ D/D(R) ∝ R-γ , where R is the rigidity of GCR particles) and an exponent ν of the PSD of the fluctuations of the strength of the IMF has been made. Data of neutron super monitors and the IMF's Bx , By , and Bz components have been used to study peculiarities of two great sporadic Forbush effects (9-23 July 1982 and 9-29 July 2000) and one recurrent Forbush effect of the 1-16 September 1996 (figures 1ab c). It is well known that one of the ma jor parameters for the characterizing of the Forbush effects of GCR is the rigidity spectrum of the GCR intensity variations, hereafter called the rigidity spectrum of Forbush effect (δ D(R)/D(R ) = A R-γ , where R is the rigidity of GCR particles and A is the power). The rigidity spectrum of the Forbush effects has been calculated using the data of neutron super monitors and the method presented, e.g. in [2,3]. There was assumed: δ D(R)/D(R) = A R-γ for R≤Rmax . And δ D(R)/D(R) = 0 for R>Rmax. Here Rmax is the upper limiting rigidity beyond which the Forbush effect of GCR intensity vanishes. Results of calculations of γ based on daily means of data for the sporadic Forbush effects, 9-23 July 1982 (14 stations), 9-29 July 2000 (11 stations) and for the recurrent Forbush effect of 1-16 September 1996 (7 stations) are presented in the figures 1def. RESULTS

  10. Magnetic domains and surface effects in hollow maghemite nanoparticles

    SciTech Connect

    Cabot, Andreu; Alivisatos, A. Paul; Puntes, Victor; Balcells, Lluis; Iglesias, Oscar; Labarta, Amilcar

    2008-09-30

    In the present work, we investigate the magnetic properties of ferrimagnetic and non-interacting maghemite hollow nanoparticles obtained by the Kirkendall effect. From the experimental characterization of their magnetic behavior, we find that polycrystalline hollow maghemite nanoparticles exhibit low blocked-to-superparamagnetic transition temperatures, small magnetic moments, significant coercivities and irreversibility fields, and no magnetic saturation on external magnetic fields up to 5 T. These results are interpreted in terms of the microstructural parameters characterizing the maghemite shells by means of atomistic Monte Carlo simulations of an individual spherical shell. The model comprises strongly interacting crystallographic domains arranged in a spherical shell with random orientations and anisotropy axis. The Monte Carlo simulation allows discernment between the influence of the polycrystalline structure and its hollow geometry, while revealing the magnetic domain arranggement in the different temperataure regimes.

  11. COSMIC-RAY CURRENT-DRIVEN TURBULENCE AND MEAN-FIELD DYNAMO EFFECT

    SciTech Connect

    Rogachevskii, Igor; Kleeorin, Nathan; Brandenburg, Axel; Eichler, David

    2012-07-01

    We show that an {alpha} effect is driven by the cosmic-ray (CR) Bell instability exciting left-right asymmetric turbulence. Alfven waves of a preferred polarization have maximally helical motion, because the transverse motion of each mode is parallel to its curl. We show how large-scale Alfven modes, when rendered unstable by CR streaming, can create new net flux over any finite region, in the direction of the original large-scale field. We perform direct numerical simulations (DNSs) of a magnetohydrodynamic fluid with a forced CR current and use the test-field method to determine the {alpha} effect and the turbulent magnetic diffusivity. As follows from DNS, the dynamics of the instability has the following stages: (1) in the early stage, the small-scale Bell instability that results in the production of small-scale turbulence is excited; (2) in the intermediate stage, there is formation of larger-scale magnetic structures; (3) finally, quasi-stationary large-scale turbulence is formed at a growth rate that is comparable to that expected from the dynamo instability, but its amplitude over much longer timescales remains unclear. The results of DNS are in good agreement with the theoretical estimates. It is suggested that this dynamo is what gives weakly magnetized relativistic shocks such as those from gamma-ray bursts (GRBs) a macroscopic correlation length. It may also be important for large-scale magnetic field amplification associated with CR production and diffusive shock acceleration in supernova remnants (SNRs) and blast waves from GRBs. Magnetic field amplification by Bell turbulence in SNRs is found to be significant, but it is limited owing to the finite time available to the super-Alfvenicly expanding remnant. The effectiveness of the mechanisms is shown to be dependent on the shock velocity. Limits on magnetic field growth in longer-lived systems, such as the Galaxy and unconfined intergalactic CRs, are also discussed.

  12. Identification of galaxy clusters in cosmic microwave background maps using the Sunyaev-Zel'dovich effect

    NASA Astrophysics Data System (ADS)

    Novaes, C. P.; Wuensche, C. A.

    2012-09-01

    Context. The Planck satellite was launched in 2009 by the European Space Agency to study the properties of the cosmic microwave background (CMB). An expected result of the Planck data analysis is the distinction of the various contaminants of the CMB signal. Among these contaminants is the Sunyaev-Zel'dovich (SZ) effect, which is caused by the inverse Compton scattering of CMB photons by high energy electrons in the intracluster medium of galaxy clusters. Aims: We modify a public version of the JADE (Joint Approximate Diagonalization of Eigenmatrices) algorithm, to deal with noisy data, and then use this algorithm as a tool to search for SZ clusters in two simulated datasets. Methods: The first dataset is composed of simple "homemade" simulations and the second of full sky simulations of high angular resolution, available at the LAMBDA (Legacy Archive for Microwave Background Data Analysis) website. The process of component separation can be summarized in four main steps: (1) pre-processing based on wavelet analysis, which performs an initial cleaning (denoising) of data to minimize the noise level; (2) the separation of the components (emissions) by JADE; (3) the calibration of the recovered SZ map; and (4) the identification of the positions and intensities of the clusters using the SExtractor software. Results: The results show that our JADE-based algorithm is effective in identifying the position and intensity of the SZ clusters, with the purities being higher then 90% for the extracted "catalogues". This value changes slightly according to the characteristics of noise and the number of components included in the input maps. Conclusions: The main highlight of our developed work is the effective recovery rate of SZ sources from noisy data, with no a priori assumptions. This powerful algorithm can be easily implemented and become an interesting complementary option to the "matched filter" algorithm (hereafter MF) widely used in SZ data analysis.

  13. Effect of a chameleon scalar field on the cosmic microwave background

    SciTech Connect

    Davis, Anne-Christine; Schelpe, Camilla A. O.; Shaw, Douglas J.

    2009-09-15

    We show that a direct coupling between a chameleonlike scalar field and photons can give rise to a modified Sunyaev-Zel'dovich (SZ) effect in the cosmic microwave background (CMB). The coupling induces a mixing between chameleon particles and the CMB photons when they pass through the magnetic field of a galaxy cluster. Both the intensity and the polarization of the radiation are modified. The degree of modification depends strongly on the properties of the galaxy cluster such as magnetic field strength and electron number density. Existing SZ measurements of the Coma cluster enable us to place constraints on the photon-chameleon coupling. The constrained conversion probability in the cluster is P{sub Coma}(204 GHz)<6.2x10{sup -5} at 95% confidence, corresponding to an upper bound on the coupling strength of g{sub eff}{sup (cell)}<2.2x10{sup -8} GeV{sup -1} or g{sub eff}{sup (Kolmo)}<(7.2-32.5)x10{sup -10} GeV{sup -1}, depending on the model that is assumed for the cluster magnetic field structure. We predict the radial profile of the chameleonic CMB intensity decrement. We find that the chameleon effect extends farther toward the edges of the cluster than the thermal SZ effect. Thus we might see a discrepancy between the x-ray emission data and the observed SZ intensity decrement. We further predict the expected change to the CMB polarization arising from the existence of a chameleonlike scalar field. These predictions could be verified or constrained by future CMB experiments.

  14. The Emergence of Cosmic Education. Spotlight: Cosmic Education.

    ERIC Educational Resources Information Center

    Trudeau, Sr. Christina Marie

    2002-01-01

    Discusses the influence of Hindu, Moslem, and Buddhist metaphysics on Maria Montessori's own pedagogical philosophy of Cosmic Education, which she regarded as the core of all learning experiences, after her visit to India. Considers the relationship between Montessori's ideas of child development and Cosmic Education, and the effect of Indian…

  15. Frequency-domain optical mammography: edge effect corrections.

    PubMed

    Fantini, S; Franceschini, M A; Gaida, G; Gratton, E; Jess, H; Mantulin, W W; Moesta, K T; Schlag, P M; Kaschke, M

    1996-01-01

    We have investigated the problem of edge effects in laser-beam transillumination scanning of the human breast. Edge effects arise from tissue thickness variability along the scanned area, and from lateral photon losses through the sides of the breast. Edge effects can be effectively corrected in frequency-domain measurements by employing a two-step procedure: (1) use of the phase information to calculate an effective tissue thickness for each pixel location; (2) application of the knowledge of tissue thickness to calculate an edge-corrected optical image from the ac signal image. The measurements were conducted with a light mammography apparatus (LIMA) designed for feasibility tests in the clinical environment. Operating in the frequency-domain (110 MHz), this instrument performs a transillumination optical scan at two wavelengths (685 and 825 nm). We applied the proposed two-step procedure to data from breast phantoms and from human breasts. The processed images provide higher contrast and detectability in optical mammography with respect to raw data breast images.

  16. Cosmic strings

    NASA Technical Reports Server (NTRS)

    Bennett, David P.

    1988-01-01

    Cosmic strings are linear topological defects which are predicted by some grand unified theories to form during a spontaneous symmetry breaking phase transition in the early universe. They are the basis for the only theories of galaxy formation aside from quantum fluctuations from inflation based on fundamental physics. In contrast to inflation, they can also be observed directly through gravitational lensing and their characterisitc microwave background anisotropy. It was recently discovered that details of cosmic string evolution are very differnt from the so-called standard model that was assumed in most of the string-induced galaxy formation calculations. Therefore, the details of galaxy formation in the cosmic string models are currently very uncertain.

  17. Effects of cosmic rays on atmospheric chlorofluorocarbon dissociation and ozone depletion.

    PubMed

    Lu, Q B; Sanche, L

    2001-08-13

    Data from satellite, balloon, and ground-station measurements show that ozone loss is strongly correlated with cosmic-ray ionization-rate variations with altitude, latitude, and time. Moreover, our laboratory data indicate that the dissociation induced by cosmic rays for CF(2)Cl(2) and CFCl(3) on ice surfaces in the polar stratosphere at an altitude of approximately 15 km is quite efficient, with estimated rates of 4.3 x 10(-5) and 3.6 x 10(-4) s(-1), respectively. These findings suggest that dissociation of chlorofluorocarbons by capture of electrons produced by cosmic rays and localized in polar stratospheric cloud ice may play a significant role in causing the ozone hole.

  18. Effects of Cosmic Rays on Atmospheric Chlorofluorocarbon Dissociation and Ozone Depletion

    SciTech Connect

    Lu, Q.-B.; Sanche, L.

    2001-08-13

    Data from satellite, balloon, and ground-station measurements show that ozone loss is strongly correlated with cosmic-ray ionization-rate variations with altitude, latitude, and time. Moreover, our laboratory data indicate that the dissociation induced by cosmic rays for CF{sub 2}Cl {sub 2} and CFCl{sub 3} on ice surfaces in the polar stratosphere at an altitude of {approx}15 km is quite efficient, with estimated rates of 4.3 x 10{sup -5} and 3.6 x 10{sup -4} s{sup -1}, respectively. These findings suggest that dissociation of chlorofluorocarbons by capture of electrons produced by cosmic rays and localized in polar stratospheric cloud ice may play a significant role in causing the ozone hole.

  19. Hall effect in charged conducting ferroelectric domain walls.

    PubMed

    Campbell, M P; McConville, J P V; McQuaid, R G P; Prabhakaran, D; Kumar, A; Gregg, J M

    2016-12-12

    Enhanced conductivity at specific domain walls in ferroelectrics is now an established phenomenon. Surprisingly, however, little is known about the most fundamental aspects of conduction. Carrier types, densities and mobilities have not been determined and transport mechanisms are still a matter of guesswork. Here we demonstrate that intermittent-contact atomic force microscopy (AFM) can detect the Hall effect in conducting domain walls. Studying YbMnO3 single crystals, we have confirmed that p-type conduction occurs in tail-to-tail charged domain walls. By calibration of the AFM signal, an upper estimate of ∼1 × 10(16) cm(-3) is calculated for the mobile carrier density in the wall, around four orders of magnitude below that required for complete screening of the polar discontinuity. A carrier mobility of∼50 cm(2)V(-1)s(-1) is calculated, about an order of magnitude below equivalent carrier mobilities in p-type silicon, but sufficiently high to preclude carrier-lattice coupling associated with small polarons.

  20. Hall effect in charged conducting ferroelectric domain walls

    PubMed Central

    Campbell, M. P.; McConville, J.P.V.; McQuaid, R.G.P.; Prabhakaran, D.; Kumar, A.; Gregg, J. M.

    2016-01-01

    Enhanced conductivity at specific domain walls in ferroelectrics is now an established phenomenon. Surprisingly, however, little is known about the most fundamental aspects of conduction. Carrier types, densities and mobilities have not been determined and transport mechanisms are still a matter of guesswork. Here we demonstrate that intermittent-contact atomic force microscopy (AFM) can detect the Hall effect in conducting domain walls. Studying YbMnO3 single crystals, we have confirmed that p-type conduction occurs in tail-to-tail charged domain walls. By calibration of the AFM signal, an upper estimate of ∼1 × 1016 cm−3 is calculated for the mobile carrier density in the wall, around four orders of magnitude below that required for complete screening of the polar discontinuity. A carrier mobility of∼50 cm2V−1s−1 is calculated, about an order of magnitude below equivalent carrier mobilities in p-type silicon, but sufficiently high to preclude carrier-lattice coupling associated with small polarons. PMID:27941794

  1. Study of heliospheric effects on galactic cosmic ray fluxes near Earth using low energy modes of the Pierre Auger Observatory

    NASA Astrophysics Data System (ADS)

    Saleh, Ahmed; Pierre Auger Collaboration

    2016-04-01

    Surface detector array (SD) of the Pierre Auger Observatory has the capability to observe variations in the flux of low energy secondary cosmic ray particles. Flux rates of low energy particles can be obtained either from particle count rates (scaler mode) or from charge distribution of the pulses (histogram mode), detected by individual water Cherenkov detectors (WCD). In scaler mode, SD is sensitive to particles that deposit energy between ~15 MeV and ~100 MeV in a WCD, while in histogram mode the deposited energy range can be extended up to ~1 GeV. These two low energy detection modes are excellent tools for monitoring modulations of the galactic cosmic ray flux, related to solar activity, such as Forbush decreases (with typical duration of several hours to weeks) and Solar cycle (with a duration of several years), as they provide fluxes of cosmic rays with different energies at the same detector. In this contribution we present an analysis of the effects of space weather and space climate on low energy mode data collected by the Pierre Auger Observatory in the period between 2006 and 2013. In particular, we focus on the long term trend of the cosmic ray flux. In addition to the standard corrections for atmospheric effects such as pressure, the analysis takes into account also the corrections for the long term evolution of the response of the surface detectors. Results show good correlation of the corrected low energy mode Auger data with neutron flux measurements by the global neutron monitoring network (NMDB).

  2. Effect of cosmic-ray shielding on the ultraweak bioluminescence emitted by cultures of Escherichia coli

    SciTech Connect

    Tilbury, R.N.; Quickenden, T.I.

    1987-11-01

    Neither the growth of Escherichia coli nor its associated luminescence was significantly affected when cultures were shielded from the soft component of cosmic rays. The study included experiments in which the cultures were shielded intermittently during their two periods of luminescence emission and experiments in which the cultures were continuously shielded throughout their entire growth cycle. These results do not support previous suggestions that the ultraweak bioluminescences from living organisms might be cosmic-ray-excited fluorescences induced in certain biological molecules synthesized during the various stages of growth.

  3. Planck 2015 results. XXIII. The thermal Sunyaev-Zeldovich effect-cosmic infrared background correlation

    NASA Astrophysics Data System (ADS)

    Planck Collaboration; Ade, P. A. R.; Aghanim, N.; Arnaud, M.; Aumont, J.; Baccigalupi, C.; Banday, A. J.; Barreiro, R. B.; Bartlett, J. G.; Bartolo, N.; Battaner, E.; Benabed, K.; Benoit-Lévy, A.; Bernard, J.-P.; Bersanelli, M.; Bielewicz, P.; Bock, J. J.; Bonaldi, A.; Bonavera, L.; Bond, J. R.; Borrill, J.; Bouchet, F. R.; Burigana, C.; Butler, R. C.; Calabrese, E.; Catalano, A.; Chamballu, A.; Chiang, H. C.; Christensen, P. R.; Churazov, E.; Clements, D. L.; Colombo, L. P. L.; Combet, C.; Comis, B.; Couchot, F.; Coulais, A.; Crill, B. P.; Curto, A.; Cuttaia, F.; Danese, L.; Davies, R. D.; Davis, R. J.; de Bernardis, P.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Dickinson, C.; Diego, J. M.; Dole, H.; Donzelli, S.; Doré, O.; Douspis, M.; Ducout, A.; Dupac, X.; Efstathiou, G.; Elsner, F.; Enßlin, T. A.; Eriksen, H. K.; Finelli, F.; Flores-Cacho, I.; Forni, O.; Frailis, M.; Fraisse, A. A.; Franceschi, E.; Galeotta, S.; Galli, S.; Ganga, K.; Génova-Santos, R. T.; Giard, M.; Giraud-Héraud, Y.; Gjerløw, E.; González-Nuevo, J.; Górski, K. M.; Gregorio, A.; Gruppuso, A.; Gudmundsson, J. E.; Hansen, F. K.; Harrison, D. L.; Helou, G.; Hernández-Monteagudo, C.; Herranz, D.; Hildebrandt, S. R.; Hivon, E.; Hobson, M.; Hornstrup, A.; Hovest, W.; Huffenberger, K. M.; Hurier, G.; Jaffe, A. H.; Jaffe, T. R.; Jones, W. C.; Keihänen, E.; Keskitalo, R.; Kisner, T. S.; Kneissl, R.; Knoche, J.; Kunz, M.; Kurki-Suonio, H.; Lagache, G.; Lamarre, J.-M.; Langer, M.; Lasenby, A.; Lattanzi, M.; Lawrence, C. R.; Leonardi, R.; Levrier, F.; Lilje, P. B.; Linden-Vørnle, M.; López-Caniego, M.; Lubin, P. M.; Macías-Pérez, J. F.; Maffei, B.; Maggio, G.; Maino, D.; Mak, D. S. Y.; Mandolesi, N.; Mangilli, A.; Maris, M.; Martin, P. G.; Martínez-González, E.; Masi, S.; Matarrese, S.; Melchiorri, A.; Mennella, A.; Migliaccio, M.; Mitra, S.; Miville-Deschênes, M.-A.; Moneti, A.; Montier, L.; Morgante, G.; Mortlock, D.; Munshi, D.; Murphy, J. A.; Nati, F.; Natoli, P.; Noviello, F.; Novikov, D.; Novikov, I.; Oxborrow, C. A.; Paci, F.; Pagano, L.; Pajot, F.; Paoletti, D.; Partridge, B.; Pasian, F.; Pearson, T. J.; Perdereau, O.; Perotto, L.; Pettorino, V.; Piacentini, F.; Piat, M.; Pierpaoli, E.; Plaszczynski, S.; Pointecouteau, E.; Polenta, G.; Ponthieu, N.; Pratt, G. W.; Prunet, S.; Puget, J.-L.; Rachen, J. P.; Reinecke, M.; Remazeilles, M.; Renault, C.; Renzi, A.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Rossetti, M.; Roudier, G.; Rubiño-Martín, J. A.; Rusholme, B.; Sandri, M.; Santos, D.; Savelainen, M.; Savini, G.; Scott, D.; Spencer, L. D.; Stolyarov, V.; Stompor, R.; Sunyaev, R.; Sutton, D.; Suur-Uski, A.-S.; Sygnet, J.-F.; Tauber, J. A.; Terenzi, L.; Toffolatti, L.; Tomasi, M.; Tristram, M.; Tucci, M.; Umana, G.; Valenziano, L.; Valiviita, J.; Van Tent, B.; Vielva, P.; Villa, F.; Wade, L. A.; Wandelt, B. D.; Wehus, I. K.; Welikala, N.; Yvon, D.; Zacchei, A.; Zonca, A.

    2016-09-01

    We use Planck data to detect the cross-correlation between the thermal Sunyaev-Zeldovich (tSZ) effect and the infrared emission from the galaxies that make up the the cosmic infrared background (CIB). We first perform a stacking analysis towards Planck-confirmed galaxy clusters. We detect infrared emission produced by dusty galaxies inside these clusters and demonstrate that the infrared emission is about 50% more extended than the tSZ effect. Modelling the emission with a Navarro-Frenk-White profile, we find that the radial profile concentration parameter is c500 = 1.00+0.18-0.15 . This indicates that infrared galaxies in the outskirts of clusters have higher infrared flux than cluster-core galaxies. We also study the cross-correlation between tSZ and CIB anisotropies, following three alternative approaches based on power spectrum analyses: (i) using a catalogue of confirmed clusters detected in Planck data; (ii) using an all-sky tSZ map built from Planck frequency maps; and (iii) using cross-spectra between Planck frequency maps. With the three different methods, we detect the tSZ-CIB cross-power spectrum at significance levels of (i) 6σ; (ii) 3σ; and (iii) 4σ. We model the tSZ-CIB cross-correlation signature and compare predictions with the measurements. The amplitude of the cross-correlation relative to the fiducial model is AtSZ-CIB = 1.2 ± 0.3. This result is consistent with predictions for the tSZ-CIB cross-correlation assuming the best-fit cosmological model from Planck 2015 results along with the tSZ and CIB scaling relations.

  4. Simplicity and Specificity in Language: Domain-General Biases Have Domain-Specific Effects

    PubMed Central

    Culbertson, Jennifer; Kirby, Simon

    2016-01-01

    The extent to which the linguistic system—its architecture, the representations it operates on, the constraints it is subject to—is specific to language has broad implications for cognitive science and its relation to evolutionary biology. Importantly, a given property of the linguistic system can be “specific” to the domain of language in several ways. For example, if the property evolved by natural selection under the pressure of the linguistic function it serves then the property is domain-specific in the sense that its design is tailored for language. Equally though, if that property evolved to serve a different function or if that property is domain-general, it may nevertheless interact with the linguistic system in a way that is unique. This gives a second sense in which a property can be thought of as specific to language. An evolutionary approach to the language faculty might at first blush appear to favor domain-specificity in the first sense, with individual properties of the language faculty being specifically linguistic adaptations. However, we argue that interactions between learning, culture, and biological evolution mean any domain-specific adaptations that evolve will take the form of weak biases rather than hard constraints. Turning to the latter sense of domain-specificity, we highlight a very general bias, simplicity, which operates widely in cognition and yet interacts with linguistic representations in domain-specific ways. PMID:26793132

  5. Effect of copper and aluminium on the event rate of cosmic ray muons at ground level in Bangi, Malaysia

    NASA Astrophysics Data System (ADS)

    Altameemi, Rasha N. I.; Gopir, G.

    2016-11-01

    In this study we determine the effect of aluminium (Al) and copper (Cu) shielding on the event rate of cosmic ray muons at ground level. The experiment was performed at Bangi in Malaysia with coordinates of 101.78° E, 2.92° N and elevation 30 m above sea level. Measurements were made along the vertical direction using muon telescopes (MTs) of parallel Geiger-Muller (GM) tubes with metal sheets above the MTs of up to 2.4 cm for Al and 2.7 cm for Cu. For these ranges of metal thicknesses, we find that the muon count rates increase linearly with the increase in metal thicknesses. The observed increase rate values are (0.18 ± 0.10) cm-1 and (0.26 ± 0.10)cm-1 for Al and Cu, respectively, with the larger value for Cu as expected from its higher atomic number and density. This indicates that for this thickness range, only the lower region of the Rossi curve is observed, with incoming cosmic ray muons producing charged particles in the metal layers, resulting in shower events or electromagnetic cascade. Thus, for this range of layer thickness, both aluminium and copper are not suitable to be used as shielding materials for ground level cosmic ray muons.

  6. Quantifying Airborne Induced Polarization effects in helicopter time domain electromagnetics

    NASA Astrophysics Data System (ADS)

    Macnae, James

    2016-12-01

    This paper derives the Airborne Induced Polarization (AIP) response of an airborne electromagnetic (AEM) system to a horizontal, thin sheet conductor. A vertical component double-dipole approximates helicopter systems with towed concentric horizontal transmitter and receiver loops in frequency- or time-domain. In time domain, the AIP effect typically shows up as late-time negative data with amplitude 4 to 5 orders of magnitude smaller than the early-time peak of the positive AEM responses. Because of limited bandwidth from the short sample time after the decay of inductive responses, accurate extraction of intrinsic AIP parameters other than a minimum chargeability is almost impossible. Modelling further suggests that AIP effects in double-dipole AEM systems can only be reliably detected from polarizable material in the top few tens of metres. A titanium mineral exploration case history from the Lac Brûlé area, Quebec, Canada illustrates strong spatial coherence of AIP minimum chargeability estimates and their independence from other effects such as conductivity and magnetic susceptibility.

  7. Multi-Scale Model of Galactic Cosmic Ray Effects on the Hippocampus

    NASA Astrophysics Data System (ADS)

    Cucinotta, Francis

    An important concern for risk assessment from galactic cosmic ray (GCR) exposures is impacts to the central nervous systems including changes in cognition, and associations with increased risk of Alzheimer’s disease (AD). AD, which affects about 50 percent of the population above age 80-yr, is a degenerative disease that worsens with time after initial onset leading to death, and has no known cure. AD is difficult to detect at early stages, and the small number of epidemiology studies that have considered the possibility have not identified an association with low dose radiation. However, experimental studies in transgenic mice suggest the possibility exits. We discuss modeling approaches to consider mechanisms whereby GCR would accelerate the occurrence of AD to earlier ages. Biomarkers of AD include Amyloid beta plaques, and neurofibrillary tangles (NFT) made up of aggregates of the hyper-phosphorylated form of the micro-tubule associated, tau protein. Related markers include synaptic degeneration, dendritic spine loss, and neuronal cell loss through apoptosis. GCR may affect these processes by causing oxidative stress, aberrant signaling following DNA damage, and chronic neuro-inflammation. Cell types considered in multi-scale models are neurons, astrocytes, and microglia. We developed biochemical and cell kinetics models of DNA damage signaling related to glycogen synthase kinase-3 beta and neuro-inflammation, and considered approaches to develop computer simulations of GCR induced cell interactions and their relationships to Amyloid beta plaques and NFTs. Comparison of model results to experimental data for the age specific development of plaques in transgenic mice and predictions of space radiation effects will be discussed.

  8. Non-linear diffusion of cosmic rays escaping from supernova remnants - I. The effect of neutrals

    NASA Astrophysics Data System (ADS)

    Nava, L.; Gabici, S.; Marcowith, A.; Morlino, G.; Ptuskin, V. S.

    2016-10-01

    Supernova remnants are believed to be the main sources of galactic cosmic rays (CR). Within this framework, particles are accelerated at supernova remnant shocks and then released in the interstellar medium. The mechanism through which CRs are released and the way in which they propagate still remain open issues. The main difficulty is the high non-linearity of the problem: CRs themselves excite the magnetic turbulence that confines them close to their sources. We solve numerically the coupled differential equations describing the evolution in space and time of the escaping particles and of the waves generated through the CR streaming instability. The warm ionized and warm neutral phases of the interstellar medium are considered. These phases occupy the largest fraction of the disc volume, where most supernovae explode, and are characterized by the significant presence of neutral particles. The friction between those neutrals and ions results in a very effective wave damping mechanism. It is found that streaming instability affects the propagation of CRs even in the presence of ion-neutral friction. The diffusion coefficient can be suppressed by more than a factor of ˜2 over a region of few tens of pc around the remnant. The suppression increases for smaller distances. The propagation of ≈10 GeV particles is affected for several tens of kiloyears after escape, while ≈1 TeV particles are affected for few kiloyears. This might have a great impact on the interpretation of gamma-ray observations of molecular clouds located in the vicinity of supernova remnants.

  9. Cosmic Balloons

    ERIC Educational Resources Information Center

    El Abed, Mohamed

    2014-01-01

    A team of French high-school students sent a weather balloon into the upper atmosphere to recreate Viktor Hess's historical experiment that demonstrated the existence of ionizing radiation from the sky--later called cosmic radiation. This discovery earned him the Nobel Prize for Physics in 1936.

  10. Cosmic Ray Neutron Flux Measurements

    NASA Astrophysics Data System (ADS)

    Dayananda, Mathes

    2009-11-01

    Cosmic rays are high-energetic particles originating from outer space that bombard the upper atmosphere of the Earth. Almost 90% of cosmic ray particles consist of protons, electrons and heavy ions. When these particles hit the Earth's atmosphere, cascade of secondary particles are formed. The most abundant particles reach to the surface of the Earth are muons, electrons and neutrons. In recent years many research groups are looking into potential applications of the effects of cosmic ray radiation at the surface of the Earth [1, 2]. At Georgia State University we are working on a long-term measurement of cosmic ray flux distribution. This study includes the simultaneous measurement of cosmic ray muons, neutrons and gamma particles at the Earth surface in downtown Atlanta. The initial effort is focusing on the correlation studies of the cosmic ray particle flux distribution and the atmospheric weather conditions. In this presentation, I will talk about the development of a cosmic ray detector using liquid scintillator and the preliminary results. [4pt] [1] K.Borozdin, G.Hogan, C.Morris, W.Priedhorsky, A.Saunders, L.Shultz, M.Teasdale, ``Radiographic imaging with cosmic-ray muons'', Nature, Vol.422, p.277, Mar.2003[0pt] [2] Svensmark Henrik, Physical Review 81, 3, (1998)

  11. Interplanetary charged particle models (1974). [and the effects of cosmic exposure upon spacecraft and spacecraft components

    NASA Technical Reports Server (NTRS)

    Divine, N.

    1975-01-01

    The design of space vehicles for operation in interplanetary space is given, based on descriptions of solar wind, solar particle events, and galactic cosmic rays. A state-of-the-art review is presented and design criteria are developed from experiment findings aboard interplanetary and high-altitude earth-orbiting spacecraft. Solar cells were found to be particularly sensitive. Solar protons may also impact the reliability of electric propulsion systems and spacecraft surfaces, as well as causing interference, detector saturation, and spurious signals. Galactic cosmic-ray impact can lead to similar electronic failure and interference and may register in photographic films and other emulsions. It was concluded that solar wind electron measurements might result from differential charging when shadowed portions of the spacecraft acquired a negative charge from electron impact.

  12. Cosmic jets

    NASA Technical Reports Server (NTRS)

    Rees, M. J.

    1986-01-01

    The evidence that active galactic nuclei produce collimated plasma jets is summarised. The strongest radio galaxies are probably energised by relativistic plasma jets generated by spinning black holes interacting with magnetic fields attached to infalling matter. Such objects can produce e(+)-e(-) plasma, and may be relevant to the acceleration of the highest-energy cosmic ray primaries. Small-scale counterparts of the jet phenomenon within our own galaxy are briefly reviewed.

  13. The effects of cosmic particle radiation on pocket mice aboard Apollo XVII: I. Project BIOCORE (M212), a biological cosmic ray experiment: procedures, summary, and conclusions.

    PubMed

    Haymaker, W; Look, B C; Winter, D L; Benton, E V; Cruty, M R

    1975-04-01

    The primary objective of the experiment was to determine whether a specific portion of the high Z-high energy (HZE)* galactic cosmic ray particle spectrum, especially particles with Z greater than or equal to 6, can produce microscopically visible injury of brain and eye tissues. Pocket mice (Perognathus longimembris), obtained from the California desert, were selected as the biological target. Five of these mice were flown on Apollo XVII. Not only the brain and eyes but also many other tissues of these animals were studied for evidence of cosmic ray particle damage. The lack of prior experimental evidence as to the character of the potential injury induced by HZE particles required reliance on the physical characteristics of particle radiation in ascertaining the probable nature of the injruy. These characteristics and the key aspects of the experiment are summarized in this paper. Subsequent articles in this special supplement give details of the biological, engineering, and dosimetric aspects of BIOCORE together with the results.

  14. Cosmic Interactions

    NASA Astrophysics Data System (ADS)

    2008-01-01

    An image based on data taken with ESO's Very Large Telescope reveals a triplet of galaxies intertwined in a cosmic dance. ESO PR Photo 02/08 ESO PR Photo 02/08 NGC 7173, 7174, and 7176 The three galaxies, catalogued as NGC 7173 (top), 7174 (bottom right) and 7176 (bottom left), are located 106 million light-years away towards the constellation of Piscis Austrinus (the 'Southern Fish'). NGC 7173 and 7176 are elliptical galaxies, while NGC 7174 is a spiral galaxy with quite disturbed dust lanes and a long, twisted tail. This seems to indicate that the two bottom galaxies - whose combined shape bears some resemblance to that of a sleeping baby - are currently interacting, with NGC 7176 providing fresh material to NGC 7174. Matter present in great quantity around the triplet's members also points to the fact that NGC 7176 and NGC 7173 have interacted in the past. Astronomers have suggested that the three galaxies will finally merge into a giant 'island universe', tens to hundreds of times as massive as our own Milky Way. ESO PR Photo 02/08 ESO PR Photo 02b/08 NGC 7173, 7174, and 7176 The triplet is part of a so-called 'Compact Group', as compiled by Canadian astronomer Paul Hickson in the early 1980s. The group, which is the 90th entry in the catalogue and is therefore known as HCG 90, actually contains four major members. One of them - NGC 7192 - lies above the trio, outside of this image, and is another peculiar spiral galaxy. Compact groups are small, relatively isolated, systems of typically four to ten galaxies in close proximity to one another. Another striking example is Robert's Quartet. Compact groups are excellent laboratories for the study of galaxy interactions and their effects, in particular the formation of stars. As the striking image reveals, there are many other galaxies in the field. Some are distant ones, while others seem to be part of the family. Studies made with other telescopes have indeed revealed that the HCG 90 group contains 16 members

  15. Cosmic impacts, cosmic catastrophes. II

    NASA Technical Reports Server (NTRS)

    Chapman, Clark R.; Morrison, David

    1990-01-01

    The role of extraterrestrial impacts in shaping the earth's history is discussed, arguing that cosmic impacts represent just one example of a general shift in thinking that has made the idea of catastrophes respectable in science. The origins of this view are presented and current catastrophic theory is discussed in the context of modern debate on the geological formation of the earth. Various conflicting theories are reviewed and prominent participants in the ongoing scientific controversy concerning catastrophism are introduced.

  16. Effective pinning energy landscape perturbations for propagating magnetic domain walls

    NASA Astrophysics Data System (ADS)

    Burn, D. M.; Atkinson, D.

    2016-10-01

    The interaction between a magnetic domain wall and a pinning site is explored in a planar nanowire using micromagnetics to reveal perturbations of the pinning energetics for propagating domain walls. Numerical simulations in the high damping ’quasi-static’ and low damping ’dynamic’ regimes are compared and show clear differences in de-pinning fields, indicating that dynamical micromagnetic models, which incorporate precessionally limited magnetization processes, are needed to understand domain wall pinning. Differences in the micromagnetic domain wall structure strongly influence the pinning and show periodic behaviour with increasing applied field associated with Walker breakdown. In the propagating regime pinning is complicated.

  17. Effective pinning energy landscape perturbations for propagating magnetic domain walls

    PubMed Central

    Burn, D. M.; Atkinson, D.

    2016-01-01

    The interaction between a magnetic domain wall and a pinning site is explored in a planar nanowire using micromagnetics to reveal perturbations of the pinning energetics for propagating domain walls. Numerical simulations in the high damping ’quasi-static’ and low damping ’dynamic’ regimes are compared and show clear differences in de-pinning fields, indicating that dynamical micromagnetic models, which incorporate precessionally limited magnetization processes, are needed to understand domain wall pinning. Differences in the micromagnetic domain wall structure strongly influence the pinning and show periodic behaviour with increasing applied field associated with Walker breakdown. In the propagating regime pinning is complicated. PMID:27694953

  18. Effective pinning energy landscape perturbations for propagating magnetic domain walls.

    PubMed

    Burn, D M; Atkinson, D

    2016-10-03

    The interaction between a magnetic domain wall and a pinning site is explored in a planar nanowire using micromagnetics to reveal perturbations of the pinning energetics for propagating domain walls. Numerical simulations in the high damping 'quasi-static' and low damping 'dynamic' regimes are compared and show clear differences in de-pinning fields, indicating that dynamical micromagnetic models, which incorporate precessionally limited magnetization processes, are needed to understand domain wall pinning. Differences in the micromagnetic domain wall structure strongly influence the pinning and show periodic behaviour with increasing applied field associated with Walker breakdown. In the propagating regime pinning is complicated.

  19. The relationship between plasma effects and cosmic radiation with TriTel-LMP common measurement in the ESEO mission

    NASA Astrophysics Data System (ADS)

    Zabori, Balazs; Hirn, Attila; Bencze, Pal

    The development of the European Student Earth Orbiter (ESEO) was announced by the Eu-ropean Space Agency for young students interested in the space exploration. The Budapest University of Technology and Economics (BUTE) joined this international cooperation with a technological innovation (Electrical Power System) and two scientific experiments, called TriTel and Langmuir Probe (LMP). The development of the TriTel 3D silicon detector telescope began in the KFKI Atomic Energy Research Institute several years ago in order to determine the av-erage radiation quality factor of the cosmic radiation for dosimetric purposes. The design of the LMP got under way at BUTE some years ago to determine the electron temperature, electron density, and electric potential of plasma. The common use of the TriTel and LMP instruments enables the simultaneous study of effects of interplanetary and magnetospheric phenomena (Tri-Tel), as well as observation of variations in the topside ionosphere (LMP). The paper presents those effects and characteristics of the magnetosphere and ionosphere that might be studied with these two instrument originally developed for different measurement goals. From the results of the experiments we expect to identify the relationship between plasma effects and cosmic radiation especially in polar regions and the South Atlantic Anomaly (SAA).

  20. Thunderstorms' atmospheric electric field effects in the intensity of cosmic ray muons and in neutron monitor data

    NASA Astrophysics Data System (ADS)

    Dorman, L. I.; Dorman, I. V.; Iucci, N.; Parisi, M.; Ne'Eman, Y.; Pustil'Nik, L. A.; Signoretti, F.; Sternlieb, A.; Villoresi, G.; Zukerman, I. G.

    2003-05-01

    Theoretical and experimental results on the influence of thunderstorms' atmospheric electric field on cosmic ray secondary components are presented. On the basis of the approach proposed by [1987], theoretical models for a correct numerical evaluation of these effects on hard muon, soft muon, and neutron monitor component are developed. For hard and soft muons the validity of the models are checked by their comparison with experimental results of the Baksan muon detector. For the first time, the effect of thunderstorms' atmospheric electric field on cosmic rays is investigated by simultaneous measurements of one-minute neutron monitor intensity and of atmospheric electric field at the Emilio Segre' Observatory on Mt. Hermon (Israel). A series of large thunderstorms during February 2000 is investigated; for each thunderstorm the maximum atmospheric electric field intensity was ranging from 10 to about 100 kV/m. Clear correlation between field intensity and neutron monitor intensity variations is presented for total intensity and for different detected multiplicity channels. This correlation is quantitatively in agreement with the developed model which takes into account the formation of short-living meso-atoms by the capture of slow negative muons in the lead of the monitor. The effect is relevant only for neutron events with detected multiplicity m = 1 and evident for multiplicity m = 2; the other multiplicity channels are not influenced by neutrons from meso-atoms.

  1. On the Rotating Effects and the Landau-Aharonov-Casher System Subject to a Hard-Wall Confining Potential in the Cosmic String Spacetime

    NASA Astrophysics Data System (ADS)

    Bakke, K.

    2015-07-01

    The behaviour of the Landau-Aharonov-Casher system is discussed by showing a case where the external electric field cannot yield the Landau-Aharonov-Casher quantization under the influence of rotating effects in the cosmic string spacetime, but it can yield bound states solutions to the Schrödinger-Pauli equation analogous to having the Landau-Aharonov-Casher system confined to a hard-wall confining potential under the influence of rotating effects and the topology of the cosmic string spacetime (by assuming ω ρ≪1 and neglecting the effects of a gravitational self-force on the particle).

  2. The effects of magnetic field modifications on the solar modulation of cosmic rays with a SDE-based model

    NASA Astrophysics Data System (ADS)

    Raath, Jan-Louis; Toit Strauss, Du; Kopp, Andreas; Potgieter, Marius

    2016-07-01

    The effects of modifying the heliospheric magnetic field, particularly in the polar regions of the heliosphere, are illustrated by utilizing a numerical model based on the solution of a set of stochastic differential equations (SDEs). Because SDE-based models are especially well suited for such studies, we are able to gain new insights into this subject. The differences in the modulation brought about by each of three choices for the heliospheric magnetic field are studied as typical well-known cases; they are the unmodified Parker field, and the Smith-Bieber and Jokipii-Kóta modified fields. It is illustrated that both these modifications change the Parker field satisfactorily in the heliospheric polar regions, but that the modification of Smith and Bieber affects a larger reduction in cosmic ray drift effects in these regions. The general features of these two modifications are illustrated and the Smith-Bieber modified field is applied in a cosmic ray modulation model to reproduce observational proton spectra from the PAMELA mission during the solar minimum of 2006 - 2009. These SDE-based results are compared to the results from other studies and found to be in good qualitative agreement.

  3. Effect of curvature on domain wall motion in elliptical nanorings

    NASA Astrophysics Data System (ADS)

    Kaya, Fikriye Idil; Bickel, Jessica; Aidala, Katherine

    2014-03-01

    Understanding domain wall (DW) motion in ferromagnetic nanostructures is important to realize proposed magnetic data storage and logic devices. We investigate the effect of curvature on DW pinning and motion by studying elliptical rings using micromagnetic simulations. Elliptical rings with constant width have varying curvature, with the lowest curvature at the minor axis, and the greatest curvature at the major axis. DWs can be created at any angular position within the ellipse by the application of an appropriate uniform magnetic field. However, only some of these positions are stable when the field is removed. We study the stability and depinning of the DWs by applying a slowly increasing elliptical magnetic field to determine the magnitude of the field at which the DWs begin to move. By varying the major to minor axis ratio, we examine the effect of curvature on DW pinning. A larger field is required to move DWs in regions of higher curvature (near the major axis) than lower curvature (near the minor axis). Overall, we see that increasing the major to minor axis ratio of elliptical nanorings requires increasing field strength to depin the DWs along the major axis. Work supported in part by NSF DMR-1207924 and NSF CMMI-1025020. Simulations performed at the CNS computational facilities at Harvard University, a member of the NNIN supported by NSF Award No. ECS-0335765.

  4. Interfacial Effects In Fragmented Domains: An Example from Breakthrough Curves

    NASA Astrophysics Data System (ADS)

    Appuhamillage, T.; Bokil, V. A.; Thomann, E.; Waymire, E. C.; Wood, B. D.

    2010-12-01

    The presence of sharp interfaces in spatially fragmented domains has an effect on dispersion that are of broad interest in geophysical, ecological and environmental applications. Specific examples include edge effects on dispersal of living organisms (C. Schultz and E. Crone, Edge-mediated dispersal behavior in a prairie butterfly, Ecology 82(7), 2001) and asymmetries in breakthrough curves in heterogeneous porous media when there is mass transport across an interface. For more examples of ecological and environmental applications see R.S. Cantrell and C. Cosner (Spatial ecology via reaction-diffusion equations, Wiley, 2003). In this poster the role of the interface condition is elucidated for the case of a conserved solute in a porous media. Using Ficks laws of advection-dispersion with continuity of the concentration and the flux across the interface, we explain recently observed asymmetries reported in the recent paper by B. Berkowitz, A. Cortis, I. Dror and H. Scher (WRR 2009). Surprisingly, in general the behavior of the breakthrough curve depends critically on the assumed interface condition and can be quite distinct in the absence of a suitable conservation law. This is based on joint work with Vrushali Bokil, Enrique Thomann, Ed Waymire and Brian Wood (WRR doi:10.1029/2009WR008258).

  5. Cosmic Catastrophes

    NASA Astrophysics Data System (ADS)

    Wheeler, J. Craig

    2000-07-01

    In this tour de force of the ultimate and extreme in astrophysics, renowned astrophysicist and author J. Craig Wheeler takes us on a breathtaking journey to supernovae, black holes, gamma-ray bursts and adventures in hyperspace. This is no far-fetched science fiction tale, but an enthusiastic exploration of ideas at the cutting edge of current astrophysics. Wheeler follows the tortuous life of a star from birth to evolution and death, and goes on to consider the complete collapse of a star into a black hole, worm-hole time machines, the possible birth of baby bubble universes, and the prospect of a revolutionary view of space and time in a ten-dimensional string theory. Along the way he offers evidence that suggests the Universe is accelerating and describes recent developments in understanding gamma-ray bursts--perhaps the most catastrophic cosmic events of all. With the use of lucid analogies, simple language and crystal-clear cartoons, Cosmic Catastrophes makes accessible some of the most exciting and mind-bending objects and ideas in the Universe. J. Craig Wheeler is currently Samuel T. and Fern Yanagisawa Regents Professor of Astronomy at the University of Texas at Austin and Vice President of the American Astronomical Society as of 1999.

  6. EFFECTS OF BIASES IN VIRIAL MASS ESTIMATION ON COSMIC SYNCHRONIZATION OF QUASAR ACCRETION

    SciTech Connect

    Steinhardt, Charles L.

    2011-09-01

    Recent work using virial mass estimates and the quasar mass-luminosity plane has yielded several new puzzles regarding quasar accretion, including a sub-Eddington boundary (SEB) on most quasar accretion, near-independence of the accretion rate from properties of the host galaxy, and a cosmic synchronization of accretion among black holes of a common mass. We consider how these puzzles might change if virial mass estimation turns out to have a systematic bias. As examples, we consider two recent claims of mass-dependent biases in Mg II masses. Under any such correction, the surprising cosmic synchronization of quasar accretion rates and independence from the host galaxy remain. The slope and location of the SEB are very sensitive to biases in virial mass estimation, and various mass calibrations appear to favor different possible physical explanations for feedback between the central black hole and its environment. The alternative mass estimators considered do not simply remove puzzling quasar behavior, but rather replace it with new puzzles that may be more difficult to solve than those using current virial mass estimators and the Shen et al. catalog.

  7. Precise Measurements of the Cosmic Ray Antiproton Spectrum with BESS Including the Effects of Solar Modulation

    NASA Technical Reports Server (NTRS)

    Mitchell, J. W.; Abe, K.; Anraku, K.; Asaoka, Y.; Fujikawa, M.; Fuke, H.; Haino, S.; Hams, T.; Ikeda, N.; Imori, M.

    2002-01-01

    The Balloon Borne Experiment with a Superconducting Spectrometer (BESS) has measured the energy spectrum of cosmic-ray antiprotons between 0.18 and 4.20 GeV in eight flights between 1993 and 2002. Above about 1 GeV, models in which antiprotons are secondary products of the interactions of primary cosmic rays with the interstellar gas agree with the BESS antiproton spectrum. Below 1 GeV, the data show a possible excess antiproton flux compared to secondary model predictions, suggesting the presence of an additional source of antiprotons. The antiproton/proton ratios measured between 1993 and 1999, during the Sun's positive-polarity phase, are consistent with simple models of solar modulation. However, results from the 2000 flight, following the solar magnetic field reversal, show a sudden increase in the antiproton/proton ratio and tend to favor a charge-sign-dependent drift model. To extend BESS measurements to lower energies, an evolutionary instrument, BESS-Polar, is under construction for polar flight in 2004.

  8. [Cytogenetic effects in experimental exposure to the heavy charged particles of galactic cosmic radiation on the Kosmos-1129 biosatellite].

    PubMed

    Nevzgodina, L V; Maksimova, E N

    1982-01-01

    The experiment was carried out on lattice (Lactuca sativa) seeds flown in a biocontainer equipped with plastic detectors to record heavy charged particles (HCP). The purpose of the experiment was to determine the yield of aberrant cells as a result of irradiation, and to identify this effect as a function of HCP topography in the seed. The cytogenetic examination of flight seedlings revealed a significant difference between the seeds which were hit with HCP and those that remained intact. This indicates a significant contribution of the heavy component of galactic cosmic rediation into the radiobiological effect. The relationship between the radiobiological effect and the HCP topography in the seed was established: zones of the root and stem meristema proved to be most sensitive targets.

  9. Cosmic strings and superconducting cosmic strings

    NASA Technical Reports Server (NTRS)

    Copeland, Edmund

    1988-01-01

    The possible consequences of forming cosmic strings and superconducting cosmic strings in the early universe are discussed. Lecture 1 describes the group theoretic reasons for and the field theoretic reasons why cosmic strings can form in spontaneously broken gauge theories. Lecture 2 discusses the accretion of matter onto string loops, emphasizing the scenario with a cold dark matter dominated universe. In lecture 3 superconducting cosmic strings are discussed, as is a mechanism which leads to the formation of structure from such strings.

  10. Influence of the superposition approximation on calculated effective dose rates from galactic cosmic rays at aerospace-related altitudes

    NASA Astrophysics Data System (ADS)

    Copeland, Kyle

    2015-07-01

    The superposition approximation was commonly employed in atmospheric nuclear transport modeling until recent years and is incorporated into flight dose calculation codes such as CARI-6 and EPCARD. The useful altitude range for this approximation is investigated using Monte Carlo transport techniques. CARI-7A simulates atmospheric radiation transport of elements H-Fe using a database of precalculated galactic cosmic radiation showers calculated with MCNPX 2.7.0 and is employed here to investigate the influence of the superposition approximation on effective dose rates, relative to full nuclear transport of galactic cosmic ray primary ions. Superposition is found to produce results less than 10% different from nuclear transport at current commercial and business aviation altitudes while underestimating dose rates at higher altitudes. The underestimate sometimes exceeds 20% at approximately 23 km and exceeds 40% at 50 km. Thus, programs employing this approximation should not be used to estimate doses or dose rates for high-altitude portions of the commercial space and near-space manned flights that are expected to begin soon.

  11. On magnetodynamic effects initiated by a high-speed impact of a large cosmic body upon the Earth's surface

    NASA Technical Reports Server (NTRS)

    Nemchinov, I. V.; Alexandrov, P. E.; Artemiev, V. I.; Bergelson, V. I.; Rybakov, V. A.

    1993-01-01

    The impact of a large cosmic body with typical size R approximately = 1 km (mass M approximately = 4-10 Gt for a stony or icy body) moving with velocity V approximately = 50-70 km/s (kinetic energy of the order of 10 exp 21 J or 10 exp 6 Mt of TMT) on the Earth's surface leads to a full vaporization of a body and of a significant part of substance of the upper layers of the Earth and even to the ionization of this vapor cloud. As a result, a hypersonic jet of air and erosion plasma is formed. The kinetic energy E sub J is far above the total energy of the geomagnetic field of the Earth (approximately equivalent to the energy of 100 Mt) and the total mass of a fast-moving part of the jet M sub j approximately = 10 exp 12 kg is far above the mass of atmosphere in the jet expansion cone. Thus, the jet will propagate practically inertially with the constant mean velocity U approximately = 10-20 km/s and even higher. The interaction of this plasma jet with the Earth's magnetic field causes magnetodynamic effects similar to those which are produced by cosmic nuclear explosions but of a larger scale. The preliminary results of experimental and numerical modeling of the plasma jet-magnetosphere interaction are presented.

  12. Cosmic Ray Removal in Fiber Spectroscopic Image

    NASA Astrophysics Data System (ADS)

    Bai, Zhongrui; Zhang, Haotong; Yuan, Hailong; Carlin, Jeffrey L.; Li, Guangwei; Lei, Yajuan; Dong, Yiqiao; Yang, Huiqin; Zhao, Yongheng; Cao, Zihuang

    2017-02-01

    Single-exposure spectra in large spectral surveys are valuable for time domain studies such as stellar variability, but there is no available method to eliminate cosmic rays for single-exposure, multi-fiber spectral images. In this paper, we describe a new method to detect and remove cosmic rays in multi-fiber spectroscopic single exposures. Through the use of two-dimensional profile fitting and a noise model that considers the position-dependent errors, we successfully detect as many as 80% of the cosmic rays and correct the cosmic ray polluted pixels to an average accuracy of 97.8%. Multiple tests and comparisons with both simulated data and real LAMOST data show that the method works properly in detection rate, false detection rate, and validity of cosmic ray correction.

  13. Effect of spin current on uniform ferromagnetism: domain nucleation.

    PubMed

    Shibata, Junya; Tatara, Gen; Kohno, Hiroshi

    2005-02-25

    A large spin current applied to a uniform ferromagnet leads to a spin-wave instability as pointed out recently. In this Letter, it is shown that such spin-wave instability is absent in a state containing a domain wall, which indicates that nucleation of magnetic domains occurs above a certain critical spin current. This scenario is supported also by an explicit energy comparison of the two states under spin current.

  14. Cosmic rays modulation of the cloud effects on the radiative flux in the Southern Hemisphere Magnetic Anomaly region

    NASA Astrophysics Data System (ADS)

    Vieira, L. E.; Silva, L.

    Aerosols are thought to cool the planet s surface through increase scattering and cloud cover and re-radiation of solar energy to space Clouds play an important role in the Earth s radiation budget through trapping outgoing radiation and reflecting incoming radiation Climate models have some representation of direct aerosol effects in them but none have yet fully included the indirect effects A correlation between a global average of low cloud cover and the flux of Galactic Cosmic Rays GCRs incident in the atmosphere has been observed recently The ionizing potential of Earth bound cosmic ray is modulated by the state of the heliosphere which depends on the solar activity 5 Here we show that in the southern Pacific Ocean the cloud effects on the net radiative flux in the atmosphere depends on the intensity of the Earth s magnetic field In the inner region of the Southern Hemisphere Magnetic Anomaly SHMA it is observed a cooling effect of approximately 18 W m 2 while in the outer region it is observed a heating effect of approximately 20 W m 2 The variability in the inner region of SHMA of the net radiative flux is correlated to GCRs flux observed in Huancayo Peru r 0 73 It is observed that correlation decrease as the intensity of the Earth s magnetic field intensity increase The observations are in agreement with the robust mechanism proposed by Brian Tinsley to explain the cloud formation due to GCRs atmospheric ionization The representation of GCRs induced cloud formation process in Coupled Atmosphere-Ocean General

  15. Cosmic strings - A problem or a solution?

    NASA Technical Reports Server (NTRS)

    Bennett, David P.; Bouchet, Francois R.

    1988-01-01

    The most fundamental issue in the theory of cosmic strings is addressed by means of Numerical Simulations: the existence of a scaling solution. The resolution of this question will determine whether cosmic strings can form the basis of an attractive theory of galaxy formation or prove to be a cosmological disaster like magnetic monopoles or domain walls. After a brief discussion of our numerical technique, results are presented which, though still preliminary, offer the best support to date of this scaling hypothesis.

  16. Beyond the Damping Tail: Cross-Correlating the Kinetic Sunyaev-Zel'dovich Effect with Cosmic Shear

    NASA Astrophysics Data System (ADS)

    Doré, Olivier; Hennawi, Joseph F.; Spergel, David N.

    2004-05-01

    Secondary anisotropies of the cosmic microwave background (CMB) have the potential to reveal intricate details about the history of our universe between the present and recombination epochs. However, because the CMB we observe is the projected sum of a multitude of effects, the interpretation of small-scale anisotropies by future high-resolution experiments will be marred by uncertainty and speculation without the handles provided by other observations. The recent controversy over the excess small-scale anisotropy detected by CBI and the BIMA array is a foretaste of potential challenges that will be faced when interpreting future experiments. In this paper we show that cross-correlating the CMB with an overlapping weak-lensing survey will isolate the elusive kinetic Sunyaev-Zel'dovich (kSZ) effect from secondary anisotropies generated at higher redshifts. We show that if upcoming high angular resolution CMB experiments, like Planck/ACT/SPT, cover the same area of sky as current and future weak-lensing surveys, like CFTHLS/SNAP/LSST, the cross-correlation of cosmic shear with the kSZ effect will be detected with high signal-to-noise ratio, increasing the potential science accessible to both sets of surveys. For example, if ACT and a CFHTLS-like survey were to overlap, this cross-correlation would be detected with a total signal-to-noise ratio greater than 220, reaching 1.8 per individual multipole around l~5000. Furthermore, this cross-correlation probes the three-point coupling between the underlying dark matter and the momentum of the ionized baryons in the densest regions of the universe at intermediate redshifts. Similar to the thermal Sunyaev-Zel'dovich (tSZ) power spectrum, its strength is extremely sensitive to the power spectrum normalization parameter, σ8, scaling roughly as σ78. It provides an effective mechanism to isolate any component of anisotropy due to patchy reionization and rule out primordial small-scale anisotropy.

  17. Cosmic plasma

    NASA Technical Reports Server (NTRS)

    Alfven, H.

    1981-01-01

    Attention is given to experimental and theoretical approaches to plasma physics, plasma phenomena in laboratory and space, field and particle aspects of plasmas, the present state of the classical theory, boundary conditions and circuit dependence, and cosmology. Electric currents in space plasmas are considered, taking into account dualism in physics, particle-related phenomena in plasma physics, magnetic field lines, filaments, local plasma properties and the circuit, electric double layers, field-aligned currents as 'cables', an expanding circuit, different types of plasma regions, the cellular structure of space, and the fine structure of active plasma regions. Other topics discussed are related to circuits, the theory of cosmic plasmas, the origin of the solar system, the coexistence of matter and antimatter, annihilation as a source of energy, the Hubble expansion in a Euclidean space, and a model for the evolution of the Metagalaxy.

  18. Effects of cosmic string velocities and the origin of globular clusters

    SciTech Connect

    Lin, Ling; Yamanouchi, Shoma; Brandenberger, Robert E-mail: shoma.yamanouchi@mail.mcgill.ca

    2015-12-01

    With the hypothesis that cosmic string loops act as seeds for globular clusters in mind, we study the role that velocities of these strings will play in determining the mass distribution of globular clusters. Loops with high enough velocities will not form compact and roughly spherical objects and can hence not be the seeds for globular clusters. We compute the expected number density and mass function of globular clusters as a function of both the string tension and the peak loop velocity, and compare the results with the observational data on the mass distribution of globular clusters in our Milky Way. We determine the critical peak string loop velocity above which the agreement between the string loop model for the origin of globular clusters (neglecting loop velocities) and observational data is lost.

  19. Nucleation of (He-3)-B from the A phase - A cosmic-ray effect?

    NASA Technical Reports Server (NTRS)

    Leggett, A. J.

    1984-01-01

    When He-3 is liquified and subsequently cooled, it undergoes, at a temperature of approximately 2.0-2.5 mK, a second-order transition into the so-called A phase. On further cooling, a first-order transition occurs, and the liquid passes into the B phase. Supercooling occurs with respect to the second transition, and the problem of nucleation arises. In connection with the experimental interest in studying metastable (He-3)-A down to the lowest temperatures in weak magnetic fields, the understanding of the mechanism of this transition and the feasibility of its inhibition is of some importance. The present investigation is concerned with the possibility that the transition is nucleated by the passage of a cosmic ray through the sample cell.

  20. Effect of time variation in the Higgs vacuum expectation value on the cosmic microwave background

    NASA Astrophysics Data System (ADS)

    Kujat, Jens; Scherrer, Robert J.

    2000-07-01

    A time variation in the Higgs vacuum expectation value alters the electron mass and thereby changes the ionization history of the universe. This change produces a measurable imprint on the pattern of cosmic microwave background (CMB) fluctuations. The nuclear masses and nuclear binding energies, as well as the Fermi coupling constant, are also altered, with negligible impact on the CMB. We calculate the changes in the spectrum of the CMB fluctuations as a function of the change in the electron mass me. We find that future CMB experiments could be sensitive to \\|Δme/me\\|~\\|ΔGF/GF\\|~10-2-10-3. However, we also show that a change in me is nearly, but not exactly, degenerate with a change in the fine-structure constant α. If both me and α are time varying, the corresponding CMB limits are much weaker, particularly for l<1000.

  1. Discrepancies between CFHTLenS cosmic shear and Planck: new physics or systematic effects?

    NASA Astrophysics Data System (ADS)

    Kitching, Thomas D.; Verde, Licia; Heavens, Alan F.; Jimenez, Raul

    2016-06-01

    There is currently a discrepancy in the measured value of the amplitude of matter clustering, parametrized using σ8, inferred from galaxy weak lensing, and cosmic microwave background (CMB) data, which could be an indication of new physics, such as massive neutrinos or a modification to the gravity law, or baryon feedback. In this paper we make the assumption that the cosmological parameters are well determined by Planck, and use weak lensing data to investigate the implications for baryon feedback and massive neutrinos, as well as possible contributions from intrinsic alignments and biases in photometric redshifts. We apply a non-parametric approach to model the baryonic feedback on the dark matter clustering, which is flexible enough to reproduce the OWLS (OverWhelmingly Large Simulations) and Illustris simulation results. The statistic we use, 3D cosmic shear, is a method that extracts cosmological information from weak lensing data using a spherical-Bessel function power spectrum approach. We analyse the CFHTLenS weak lensing data and, assuming best-fitting cosmological parameters from the Planck CMB experiment, find that there is no evidence for baryonic feedback on the dark matter power spectrum, but there is evidence for a bias in the photometric redshifts in the CFHTLenS data, consistent with a completely independent analysis by Choi et al., based on spectroscopic redshifts, and that these conclusions are robust to assumptions about the intrinsic alignment systematic. We also find an upper limit, of <0.28 eV (1σ), to the sum of neutrino masses conditional on other Λ-cold-dark-matter parameters being fixed.

  2. Chemical and physical effects induced by heavy cosmic ray analogues on frozen methanol and water ice mixtures

    NASA Astrophysics Data System (ADS)

    de Barros, A. L. F.; da Silveira, E. F.; Rothard, H.; Langlinay, T.; Boduch, P.

    2014-09-01

    The chemical and physical effects induced by fast heavy-ion irradiation on a frozen mixture of methanol (CH3OH) and water (H2O) at 15 K are analysed. The laboratory experiment described here simulates the energy transfer processes that occur when cosmic rays bombard this particular ice mixture and helps to elucidate the understanding of the radiolysis of ices occurring in interstellar medium grains, at the surfaces of comets, and on icy Solar system bodies. Infrared spectroscopy (FTIR) was used before and during irradiation with a 40 MeV 58Ni11+ ion beam to determine the variation of the main absorption bands of methanol, water and products. In particular, the radiolysis of CH3OH:H2O (1:1) mixture leads to the formation of H2CO, CH4, CO, CO2, HCO and HCOOCH3. Their formation and dissociation cross-sections are determined. H2CO, CH4 and HCOOCH3 molecules have relatively high destruction cross-sections of around 9 × 10-13 cm2. Furthermore, atomic carbon, oxygen and hydrogen budgets are determined and used to verify the stoichiometry of the most abundant molecular species formed. Temperature effects are compared with irradiation effects, and the spectra of samples warmed-up to different temperatures are compared with those of the irradiated CH3OH:H2O mixtures. As an astrophysical application, the CH3OH:H2O dissociation cross-sections due to other ion beam projectiles and energies are predicted assuming validity of the Se3/2 power law; calculation of the integrated dissociation rates confirms the importance of nickel and some other heavy-ion constituents of cosmic rays in astrochemistry.

  3. Dislocation Effects on the Diffraction Line Profiles from Nanocrystalline Domains

    NASA Astrophysics Data System (ADS)

    Leonardi, Alberto; Scardi, Paolo

    2016-12-01

    A Pd nano-polycrystalline microstructure was simulated by molecular dynamics, including edge or screw dislocations in one of the 50 grains, so as to produce a realistic model of nanocrystalline domain with line defect. The same crystalline domain was also studied, with or without line defects, as a free-standing, isolated nanocrystal. Atomic coordinates of the selected domain were used to generate powder patterns by means of the Debye scattering equation, and these patterns were used as "experimental" data to test existing methods of line profile analysis in controlled condition, i.e., with known type and density of defects. Results show that the Krivolgaz-Wilkens theory of dislocation line broadening qualitatively agrees with the MD model, but errors can be larger than 50 pct. A critical issue arises from the instability of the Krivolgaz-Wilkens model when all line profile parameters are simultaneously refined: reasonable results can be obtained by fixing or restricting some parameters.

  4. Effects of sub-domain structure on initial magnetization curve and domain size distribution of stacked media

    NASA Astrophysics Data System (ADS)

    Sato, S.; Kumagai, S.; Sugita, R.

    2015-03-01

    In this paper, in order to confirm the sub-domain structure in stacked media demagnetized with in-plane field, initial magnetization curves and magnetic domain size distribution were investigated. Both experimental and simulation results showed that an initial magnetization curve for the medium demagnetized with in-plane field (MDI) initially rose faster than that for the medium demagnetized with perpendicular field (MDP). It is inferred that this is because the MDI has a larger number of domain walls than the MDP due to the existence of the sub-domains, resulting in an increase in the probability of domain wall motion. Dispersion of domain size for the MDI was larger than that for the MDP. This is because sub-domains are formed not only inside the domain but also at the domain boundary region, and they change the position of the domain boundary to affect the domain size.

  5. Essential Knowledge Domains Underlying Effective Rehabilitation Counseling Practice

    ERIC Educational Resources Information Center

    Leahy, Michael J.; Muenzen, Patricia; Saunders, Jodi L.; Strauser, David

    2009-01-01

    The purpose of this study was to identify and examine the major knowledge domains required for rehabilitation counseling practice across settings in today's rapidly changing practice environment. Data obtained and analyzed from a recent national study by the Commission on Rehabilitation Counselor Certification (CRCC) is reported and reviewed in…

  6. Photochemistry of PAHs in cosmic water ice. The effect of concentration on UV-VIS spectroscopy and ionization efficiency

    NASA Astrophysics Data System (ADS)

    Cuylle, Steven H.; Allamandola, Louis J.; Linnartz, Harold

    2014-02-01

    Context. Observations and models show that polycyclic aromatic hydrocarbons (PAHs) are ubiquitous in the interstellar medium. Like other molecules in dense clouds, PAHs accrete onto interstellar dust grains, where they are embedded in an ice matrix dominated by water. In the laboratory, mixed molecular ices (not containing PAHs) have been extensively studied using Fourier transform infrared absorption spectroscopy. Experiments including PAHs in ices have started, however, the concentrations used are typically much higher than the concentrations expected for interstellar ices. Optical spectroscopy offers a sensitive alternative. Aims: We report an experimental study of the effect PAH concentration has on the electronic spectra and the vacuum UV (VUV) driven processes of PAHs in water-rich ices. The goal is to apply the outcome to cosmic ices. Methods: Optical spectroscopic studies allow us to obtain in-situ and quasi real-time electronic solid state spectra of two prototypical PAHs (pyrene and coronene) embedded in water ice under VUV photoprocessing. The study is carried out on PAH:H2O concentrations in the range of 1:30 000 to pure PAH, covering the temperature range from 12 to 125 K. Results: PAH concentration strongly influences the efficiency of PAH cation formation. At low concentrations, ionization efficiencies are over 60% dropping to about 15% at 1:1000. Increasing the PAH concentration reveals spectral broadening in neutral and cation PAH spectra attributed to PAH clustering inside the ice. At the PAH concentrations expected for interstellar ices, some 10 to 20% may be present as cations. The presence of PAHs in neutral and ion form will add distinctive absorption bands to cosmic ice optical spectra and this may serve as a tool to determine PAH concentrations.

  7. Superposed epoch study of ICME sub-structures near Earth and their effects on Galactic cosmic rays

    NASA Astrophysics Data System (ADS)

    Masías-Meza, J. J.; Dasso, S.; Démoulin, P.; Rodriguez, L.; Janvier, M.

    2016-08-01

    Context. Interplanetary coronal mass ejections (ICMEs) are the interplanetary manifestations of solar eruptions. The overtaken solar wind forms a sheath of compressed plasma at the front of ICMEs. Magnetic clouds (MCs) are a subset of ICMEs with specific properties (e.g. the presence of a flux rope). When ICMEs pass near Earth, ground observations indicate that the flux of Galactic cosmic rays (GCRs) decreases. Aims: The main aims of this paper are to find common plasma and magnetic properties of different ICME sub-structures and which ICME properties affect the flux of GCRs near Earth. Methods: We used a superposed epoch method applied to a large set of ICMEs observed in situ by the spacecraft ACE, between 1998 and 2006. We also applied a superposed epoch analysis on GCRs time series observed with the McMurdo neutron monitors. Results: We find that slow MCs at 1 AU have on average more massive sheaths. We conclude that this is because they are more effectively slowed down by drag during their travel from the Sun. Slow MCs also have a more symmetric magnetic field and sheaths expanding similarly as their following MC, while in contrast, fast MCs have an asymmetric magnetic profile and a sheath in compression. In all types of MCs, we find that the proton density and the temperature and the magnetic fluctuations can diffuse within the front of the MC due to 3D reconnection. Finally, we derive a quantitative model that describes the decrease in cosmic rays as a function of the amount of magnetic fluctuations and field strength. Conclusions: The obtained typical profiles of sheath, MC and GCR properties corresponding to slow, middle, and fast ICMEs, can be used for forecasting or modelling these events, and to better understand the transport of energetic particles in ICMEs. They are also useful for improving future operative space weather activities.

  8. Lunar radiation environment and space weathering from the Cosmic Ray Telescope for the Effects of Radiation (CRaTER)

    NASA Astrophysics Data System (ADS)

    Schwadron, N. A.; Baker, T.; Blake, B.; Case, A. W.; Cooper, J. F.; Golightly, M.; Jordan, A.; Joyce, C.; Kasper, J.; Kozarev, K.; Mislinski, J.; Mazur, J.; Posner, A.; Rother, O.; Smith, S.; Spence, H. E.; Townsend, L. W.; Wilson, J.; Zeitlin, C.

    2012-03-01

    The Cosmic Ray Telescope for the Effects of Radiation (CRaTER) measures linear energy transfer by Galactic Cosmic Rays (GCRs) and Solar Energetic Particles (SEPs) on the Lunar Reconnaissance Orbiter (LRO) Mission in a circular, polar lunar orbit. GCR fluxes remain at the highest levels ever observed during the space age. One of the largest SEP events observed by CRaTER during the LRO mission occurred on June 7, 2011. We compare model predictions by the Earth-Moon-Mars Radiation Environment Module (EMMREM) for both dose rates from GCRs and SEPs during this event with results from CRaTER. We find agreement between these models and the CRaTER dose rates, which together demonstrate the accuracy of EMMREM, and its suitability for a real-time space weather system. We utilize CRaTER to test forecasts made by the Relativistic Electron Alert System for Exploration (REleASE), which successfully predicts the June 7th event. At the maximum CRaTER-observed GCR dose rate (˜11.7 cGy/yr where Gy is a unit indicating energy deposition per unit mass, 1 Gy = 1 J/kg), GCRs deposit ˜88 eV/molecule in water over 4 billion years, causing significant change in molecular composition and physical structure (e.g., density, color, crystallinity) of water ice, loss of molecular hydrogen, and production of more complex molecules linking carbon and other elements in the irradiated ice. This shows that space weathering by GCRs may be extremely important for chemical evolution of ice on the Moon. Thus, we show comprehensive observations from the CRaTER instrument on the Lunar Reconnaissance Orbiter that characterizes the radiation environment and space weathering on the Moon.

  9. Cosmic Rays and Dynamical Meteorology, 2. Snow Effect In Different Multiplicities According To Neutron Monitor Data of Emilio Segre' Observatory

    NASA Astrophysics Data System (ADS)

    Dorman, L. I.; Iucci, N.; Pustil'Nik, L. A.; Sternlieb, A.; Villoresi, G.; Zukerman, I. G.

    On the basis of cosmic ray hourly data obtained by NM of Emilio Segre' Observatory (hight 2025 m above s.l., cut-off rigidity for vertical direction 10.8 GV) we determine the snow effect in CR for total neutron intensity and for multiplicities m=1, m=2, m=3, m=4, m=5, m=6, and m=7. For comparison and excluding primary CR variations we use also hourly data on neutron multiplicities obtained by Rome NM (about sea level, cut-off rigidity 6.7 GV). In this paper we will analize effects of snow in periods from 4 January 2000 to 15 April 2000 with maximal absorption effect about 5%, and from 21 December 2000 up to 31 March 2001 with maximal effect 13% in the total neu- tron intensity. We use the periods without snow to determine regeression coefficients between primary CR variations observed by NM of Emilio Segre' Observatory, and by Rome NM. On the basis of obtained results we develop a method to correct data on snow effect by using several NM hourly data. On the basis of our data we estimate the accuracy with what can be made correction of NM data of stations where the snow effect can be important.

  10. Electrical effects of spin density wave quantization and magnetic domain walls in chromium.

    PubMed

    Kummamuru, Ravi K; Soh, Yeong-Ah

    2008-04-17

    The role of magnetic domains (and the walls between domains) in determining the electrical properties of ferromagnetic materials has been investigated in great detail for many years, not least because control over domains offers a means of manipulating electron spin to control charge transport in 'spintronic' devices. In contrast, much less attention has been paid to the effects of domains and domain walls on the electrical properties of antiferromagnets: antiferromagnetic domains show no net external magnetic moment, and so are difficult to manipulate or probe. Here we describe electrical measurements on chromium--a simple metal and quintessential spin density wave antiferromagnet--that show behaviour directly related to spin density wave formation and the presence of antiferromagnetic domains. Two types of thermal hysteresis are seen in both longitudinal and Hall resistivity: the first can be explained by the quantization of spin density waves due to the finite film thickness (confirmed by X-ray diffraction measurements) and the second by domain-wall scattering of electrons. We also observe the striking influence of the electrical lead configuration (a mesoscopic effect) on the resistivity of macroscopic samples in the spin density wave state. Our results are potentially of practical importance, in that they reveal tunable electrical effects of film thickness and domain walls that are as large as the highest seen for ferromagnets.

  11. Efficacy of Cosmic Ray Shields

    NASA Astrophysics Data System (ADS)

    Rhodes, Nicholas

    2015-10-01

    This research involved testing various types of shielding with a self-constructed Berkeley style cosmic ray detector, in order to evaluate the materials of each type of shielding's effectiveness at blocking cosmic rays and the cost- and size-efficiency of the shields as well. The detector was constructed, then tested for functionality and reliability. Following confirmation, the detector was then used at three different locations to observe it altitude or atmospheric conditions had any effect on the effectiveness of certain shields. Multiple types of shielding were tested with the detector, including combinations of several shields, primarily aluminum, high-iron steel, polyethylene plastic, water, lead, and a lead-alternative radiation shield utilized in radiology. These tests regarding both the base effectiveness and the overall efficiency of shields is designed to support future space exploratory missions where the risk of exposure to possibly lethal amounts of cosmic rays for crew and the damage caused to unshielded electronics are of serious concern.

  12. THE INTERACTION OF COSMIC RAYS WITH DIFFUSE CLOUDS

    SciTech Connect

    Everett, John E.; Zweibel, Ellen G.

    2011-10-01

    We study the change in cosmic-ray pressure, the change in cosmic-ray density, and the level of cosmic-ray-induced heating via Alfven-wave damping when cosmic rays move from a hot ionized plasma to a cool cloud embedded in that plasma. The general analysis method outlined here can apply to diffuse clouds in either the ionized interstellar medium or in galactic winds. We introduce a general-purpose model of cosmic-ray diffusion building upon the hydrodynamic approximation for cosmic rays (from McKenzie and Voelk and Breitschwerdt and collaborators). Our improved method self-consistently derives the cosmic-ray flux and diffusivity under the assumption that the streaming instability is the dominant mechanism for setting the cosmic-ray flux and diffusion. We find that, as expected, cosmic rays do not couple to gas within cool clouds (cosmic rays exert no forces inside of cool clouds), that the cosmic-ray density does not increase within clouds (it may decrease slightly in general, and decrease by an order of magnitude in some cases), and that cosmic-ray heating (via Alfven-wave damping and not collisional effects as for {approx}10 MeV cosmic rays) is only important under the conditions of relatively strong (10 {mu}G) magnetic fields or high cosmic-ray pressure ({approx}10{sup -11} erg cm{sup -3}).

  13. Kinetics of CO binding to the haem domain of murine inducible nitric oxide synthase: differential effects of haem domain ligands.

    PubMed Central

    Stevenson, T H; Gutierrez, A F; Alderton, W K; Lian , L; Scrutton, N S

    2001-01-01

    The binding of CO to the murine inducible nitric oxide synthase (iNOS) oxygenase domain has been studied by laser flash photolysis. The effect of the (6R)-5,6,7,8-tetrahydro-L-biopterin (BH(4)) cofactor L-arginine and several Type I L-arginine analogues/ligands on the rates of CO rebinding has been evaluated. The presence of BH(4) in the iNOS active site has little effect on the rebinding of protein-caged haem-CO pairs (geminate recombination), but decreases the bimolecular association rates 2-fold. Addition of L-arginine to the BH(4)-bound complex completely abolishes geminate recombination and results in a further 80-fold decrease in the overall rate of bimolecular association. Three of the Type I ligands, S-ethylisothiourea, L-canavanine and 2,5-lutidine, displaced the CO from the haem iron upon addition to the iNOS oxygenase domain. The Type I ligands significantly decreased the rate of bimolecular binding of CO to the haem iron after photolysis. Most of these ligands also completely abolished geminate recombination. These results are consistent with a relatively open distal pocket that allows CO to bind unhindered in the active site of murine iNOS in the absence of L-arginine or BH(4). In the presence of BH(4) and L-arginine, however, the enzyme adopts a more closed structure that can greatly reduce ligand access to the haem iron. These observations are discussed in terms of the known structure of iNOS haem domain and solution studies of ligand binding in iNOS and neuronal NOS isoenzymes. PMID:11485568

  14. The Effects of Domain Knowledge and Instructional Manipulation on Creative Idea Generation

    ERIC Educational Resources Information Center

    Hao, Ning

    2010-01-01

    The experiment was designed to explore the effects of domain knowledge, instructional manipulation, and the interaction between them on creative idea generation. Three groups of participants who respectively possessed the domain knowledge of biology, sports, or neither were asked to finish two tasks: imagining an extraterrestrial animal and…

  15. 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.

  16. High energy electron irradiation of interstellar carbonaceous dust analogs: Cosmic ray effects on the carriers of the 3.4 µm absorption band.

    PubMed

    Maté, Belén; Molpeceres, Germán; Jiménez-Redondo, Miguel; Tanarro, Isabel; Herrero, Víctor J

    2016-11-01

    The effects of cosmic rays on the carriers of the interstellar 3.4 μm absorption band have been investigated in the laboratory. This band is attributed to stretching vibrations of CH3 and CH2 in carbonaceous dust. It is widely observed in the diffuse interstellar medium (ISM), but disappears in dense clouds. Destruction of CH3 and CH2 by cosmic rays could become relevant in dense clouds, shielded from the external ultraviolet field. For the simulations, samples of hydrogenated amorphous carbon (a-C:H) have been irradiated with 5 keV electrons. The decay of the band intensity vs electron fluence reflects a-C:H dehydrogenation, which is well described by a model assuming that H2 molecules, formed by the recombination of H atoms liberated through CH bond breaking, diffuse out of the sample. The CH bond destruction rates derived from the present experiments are in good accordance with those from previous ion irradiation experiments of HAC. The experimental simplicity of electron bombardment has allowed the use of higher energy doses than in the ion experiments. The effects of cosmic rays on the aliphatic components of cosmic dust are found to be small. The estimated cosmic ray destruction times for the 3.4 μm band carriers lie in the 10(8) yr range and cannot account for the disappearance of this band in dense clouds, which have characteristic lifetimes of 3 × 10(7) yr. The results invite a more detailed investigation of the mechanisms of CH bond formation and breaking in the intermediate region between diffuse and dense clouds.

  17. High energy electron irradiation of interstellar carbonaceous dust analogs: Cosmic ray effects on the carriers of the 3.4 µm absorption band

    PubMed Central

    Maté, Belén; Molpeceres, Germán; Jiménez-Redondo, Miguel; Tanarro, Isabel; Herrero, Víctor J.

    2017-01-01

    The effects of cosmic rays on the carriers of the interstellar 3.4 μm absorption band have been investigated in the laboratory. This band is attributed to stretching vibrations of CH3 and CH2 in carbonaceous dust. It is widely observed in the diffuse interstellar medium (ISM), but disappears in dense clouds. Destruction of CH3 and CH2 by cosmic rays could become relevant in dense clouds, shielded from the external ultraviolet field. For the simulations, samples of hydrogenated amorphous carbon (a-C:H) have been irradiated with 5 keV electrons. The decay of the band intensity vs electron fluence reflects a-C:H dehydrogenation, which is well described by a model assuming that H2 molecules, formed by the recombination of H atoms liberated through CH bond breaking, diffuse out of the sample. The CH bond destruction rates derived from the present experiments are in good accordance with those from previous ion irradiation experiments of HAC. The experimental simplicity of electron bombardment has allowed the use of higher energy doses than in the ion experiments. The effects of cosmic rays on the aliphatic components of cosmic dust are found to be small. The estimated cosmic ray destruction times for the 3.4 μm band carriers lie in the 108 yr range and cannot account for the disappearance of this band in dense clouds, which have characteristic lifetimes of 3 × 107 yr. The results invite a more detailed investigation of the mechanisms of CH bond formation and breaking in the intermediate region between diffuse and dense clouds. PMID:28133388

  18. High-energy Electron Irradiation of Interstellar Carbonaceous Dust Analogs: Cosmic-ray Effects on the Carriers of the 3.4 μm Absorption Band

    NASA Astrophysics Data System (ADS)

    Maté, Belén; Molpeceres, Germán; Jiménez-Redondo, Miguel; Tanarro, Isabel; Herrero, Víctor J.

    2016-11-01

    The effects of cosmic rays on the carriers of the interstellar 3.4 μm absorption band have been investigated in the laboratory. This band is attributed to stretching vibrations of CH3 and CH2 in carbonaceous dust. It is widely observed in the diffuse interstellar medium, but disappears in dense clouds. Destruction of CH3 and CH2 by cosmic rays could become relevant in dense clouds, shielded from the external ultraviolet field. For the simulations, samples of hydrogenated amorphous carbon (a-C:H) have been irradiated with 5 keV electrons. The decay of the band intensity versus electron fluence reflects a-C:H dehydrogenation, which is well described by a model assuming that H2 molecules, formed by the recombination of H atoms liberated through CH bond breaking, diffuse out of the sample. The CH bond destruction rates derived from the present experiments are in good accordance with those from previous ion irradiation experiments of HAC. The experimental simplicity of electron bombardment has allowed the use of higher-energy doses than in the ion experiments. The effects of cosmic rays on the aliphatic components of cosmic dust are found to be small. The estimated cosmic-ray destruction times for the 3.4 μm band carriers lie in the 108 yr range and cannot account for the disappearance of this band in dense clouds, which have characteristic lifetimes of 3 × 107 yr. The results invite a more detailed investigation of the mechanisms of CH bond formation and breaking in the intermediate region between diffuse and dense clouds.

  19. Mass and radius of cosmic balloons

    NASA Technical Reports Server (NTRS)

    Wang, Yun

    1994-01-01

    Cosmic balloons are spherical domain walls with relativistic particles trapped inside. We derive the exact mass and radius relations for a static cosmic balloon using Gauss-Codazzi equations. The cosmic balloon mass as a function of its radius, M(R), is found to have a functional form similar to that of fermion soliton stars, with a fixed point at 2GM(R)/R approximately or equal to 0.486 which corresponds to the limit of infinite central density. We derive a simple analytical approximation for the mass density of a spherically symmetric relativistic gas star. When applied to the computation of the mass and radius of a cosmic balloon, the analytical approximation yields fairly good agreement with the exact numerical solutions.

  20. On the domain size effect of thermal conductivities from equilibrium and nonequilibrium molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Wang, Zuyuan; Ruan, Xiulin

    2017-01-01

    Equilibrium molecular dynamics (EMD) simulations with the Green-Kubo formula and nonequilibrium molecular dynamics (NEMD) simulations with the Fourier's Law are two widely used methods for calculating thermal conductivities of materials. It is well known that both methods suffer from domain size effects, especially for NEMD. But the underlying mechanisms and their comparison have not been much quantitatively studied before. In this paper, we investigate their domain size effects by using crystalline silicon at 1000 K, graphene at 300 K, and silicene at 300 K as model material systems. The thermal conductivity of silicon from EMD simulations increases normally with the increasing domain size and converges at a size of around 4 ×4 ×4 nm3 . The converging trend agrees well with the wavelength-accumulated thermal conductivity. The thermal conductivities of graphene and silicene from EMD simulations decrease abnormally with the increasing domain size and converge at a size of around 10 ×10 nm2 . We ascribe the anomalous size effect to the fact that as the domain size increases, the effect of more phonon scattering processes (particularly the flexural phonons) dominates over the effect of more phonon modes contributing to the thermal conductivity. The thermal conductivities of the three material systems from NEMD simulations all show normal domain size effects, although their dependences on the domain size differ. The converging trends agree with the mean free path accumulation of thermal conductivity. This study provides new insights that other than some exceptions, the domain size effects of EMD and NEMD are generally associated with wavelength and mean free path accumulations of thermal conductivity, respectively. Since phonon wavelength spans over a much narrower range than mean free path, EMD usually has less significant domain size effect than NEMD.

  1. Mechanistic investigation of domain specific unfolding of human serum albumin and the effect of sucrose.

    PubMed

    Yadav, Rajeev; Sen, Pratik

    2013-11-01

    This study is devoted to understand the unfolding mechanism of a multidomain protein, human serum albumin (HSA), in absence and presence of the sucrose by steady-state and time-resolved fluorescence spectroscopy with domain specific marker molecules and is further being substantiated by molecular dynamics (MD) simulation. In water, the domain III of HSA found to unfold first followed by domains I and II as the concentration of GnHCl is increased in the medium. The sequential unfolding behavior of different domains of HSA remains same in presence of sucrose; however, a higher GnHCl concentration is required for unfolding, suggesting stabilizing effect of sucrose on HSA. Domain I is found to be most stabilized by sucrose. The stabilization of domain II is somewhat similar to domain I, but the effect of sucrose on domain III is found to be very small. MD simulation also predicted a similar behavior of sucrose on HSA. The stabilizing effect of sucrose is explained in terms of the entrapment of water molecules in between HSA surface and sucrose layer as well as direct interaction between HSA and sucrose.

  2. Mechanistic investigation of domain specific unfolding of human serum albumin and the effect of sucrose

    PubMed Central

    Yadav, Rajeev; Sen, Pratik

    2013-01-01

    This study is devoted to understand the unfolding mechanism of a multidomain protein, human serum albumin (HSA), in absence and presence of the sucrose by steady-state and time-resolved fluorescence spectroscopy with domain specific marker molecules and is further being substantiated by molecular dynamics (MD) simulation. In water, the domain III of HSA found to unfold first followed by domains I and II as the concentration of GnHCl is increased in the medium. The sequential unfolding behavior of different domains of HSA remains same in presence of sucrose; however, a higher GnHCl concentration is required for unfolding, suggesting stabilizing effect of sucrose on HSA. Domain I is found to be most stabilized by sucrose. The stabilization of domain II is somewhat similar to domain I, but the effect of sucrose on domain III is found to be very small. MD simulation also predicted a similar behavior of sucrose on HSA. The stabilizing effect of sucrose is explained in terms of the entrapment of water molecules in between HSA surface and sucrose layer as well as direct interaction between HSA and sucrose. PMID:24038622

  3. Ion irradiation of carbonaceous interstellar analogues. Effects of cosmic rays on the 3.4 μm interstellar absorption band

    NASA Astrophysics Data System (ADS)

    Godard, M.; Féraud, G.; Chabot, M.; Carpentier, Y.; Pino, T.; Brunetto, R.; Duprat, J.; Engrand, C.; Bréchignac, P.; D'Hendecourt, L.; Dartois, E.

    2011-05-01

    Context. A 3.4 μm absorption band (around 2900 cm-1), assigned to aliphatic C-H stretching modes of hydrogenated amorphous carbons (a-C:H), is widely observed in the diffuse interstellar medium, but disappears or is modified in dense clouds. This spectral difference between different phases of the interstellar medium reflects the processing of dust in different environments. Cosmic ray bombardment is one of the interstellar processes that make carbonaceous dust evolve. Aims: We investigate the effects of cosmic rays on the interstellar 3.4 μm absorption band carriers. Methods: Samples of carbonaceous interstellar analogues (a-C:H and soot) were irradiated at room temperature by swift ions with energy in the MeV range (from 0.2 to 160 MeV). The dehydrogenation and chemical bonding modifications that occurred during irradiation were studied with IR spectroscopy. Results: For all samples and all ions/energies used, we observed a decrease of the aliphatic C-H absorption bands intensity with the ion fluence. This evolution agrees with a model that describes the hydrogen loss as caused by the molecular recombination of two free H atoms created by the breaking of C-H bonds by the impinging ions. The corresponding destruction cross section and asymptotic hydrogen content are obtained for each experiment and their behaviour over a large range of ion stopping powers are inferred. Using elemental abundances and energy distributions of galactic cosmic rays, we investigated the implications of these results in different astrophysical environments. The results are compared to the processing by UV photons and H atoms in different regions of the interstellar medium. Conclusions: The destruction of aliphatic C-H bonds by cosmic rays occurs in characteristic times of a few 108 years, and it appears that even at longer time scales, cosmic rays alone cannot explain the observed disappearance of this spectral signature in dense regions. In diffuse interstellar medium, the formation

  4. Is cosmic acceleration slowing down?

    SciTech Connect

    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 and 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)

  5. RED SUPERGIANT STARS AS COSMIC ABUNDANCE PROBES: NLTE EFFECTS IN J-BAND IRON AND TITANIUM LINES

    SciTech Connect

    Bergemann, Maria; Kudritzki, Rolf-Peter; Lind, Karin; Plez, Bertrand; Davies, Ben; Gazak, Zach E-mail: klind@mpa-garching.mpg.de E-mail: zgazak@ifa.hawaii.edu E-mail: bdavies@ast.cam.ac.uk

    2012-06-01

    Detailed non-LTE (NLTE) calculations for red supergiant (RSG) stars are presented to investigate the influence of NLTE on the formation of atomic iron and titanium lines in the J band. With their enormous brightness at J band RSG stars are ideal probes of cosmic abundances. Recent LTE studies have found that metallicities accurate to 0.15 dex can be determined from medium-resolution spectroscopy of individual RSGs in galaxies as distant as 10 Mpc. The NLTE results obtained in this investigation support these findings. NLTE abundance corrections for iron are smaller than 0.05 dex for effective temperatures between 3400 K and 4200 K and 0.1 dex at 4400 K. For titanium the NLTE abundance corrections vary smoothly between -0.4 dex and +0.2 dex as a function of effective temperature. For both elements, the corrections also depend on stellar gravity and metallicity. The physical reasons behind the NLTE corrections and the consequences for extragalactic J-band abundance studies are discussed.

  6. Stress Domain Effects in French Phonology and Phonological Development*

    PubMed Central

    Rose, Yvan; dos Santos, Christophe

    2016-01-01

    In this paper, we discuss two distinct data sets. The first relates to the so-called allophonic process of closed-syllable laxing in Québec French, which targets final (stressed) vowels even though these vowels are arguably syllabified in open syllables in lexical representations. The second is found in the forms produced by a first language learner of European French, who displays an asymmetry in her production of CVC versus CVCV target (adult) forms. The former display full preservation (with concomitant manner harmony) of both consonants. The latter undergoes deletion of the initial syllable if the consonants are not manner-harmonic in the input. We argue that both patterns can be explained through a phonological process of prosodic strengthening targeting the head of the prosodic domain which, in the contexts described above, yields the incorporation of final consonants into the coda of the stressed syllable. PMID:27227170

  7. 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.

  8. Domain wall motion and Barkhausen effect in magnetic nanoparticles for EOR applications

    NASA Astrophysics Data System (ADS)

    Baig, Mirza Khurram; Soleimani, Hassan; Yahya, Noorhana

    2016-11-01

    The domain wall motion in magnetic nanoparticles is a useful parameter of study. The subject of this research is to study of the phenomenon of discontinuous domain wall motion, or the Barkhausen Effect in magnetic nanoparticles. In this work hematite (Fe2O3) nanoparticles have been synthesized using sol-gel auto-combustion and characterized using X-ray diffraction, Field emission scanning electron microscopy (FESEM), Transmission electron microscope (TEM) and Vibrating sample magnetometer (VSM) for crystal structure, morphology, shape, size and magnetic properties respectively. The FESEM and TEM results show that the particles are spherical in nature and average size is 60nm that is suitable for domain walls and barkhuasen effect. The VSM results show high coercivity 175 Oe and low saturation magnetization due to domain wall pinning and barkhausen effect. The size and magnetic properties reveals the existence of domain walls in the synthesized sample. The magnetic properties confirm the energy losses due to domain wall pinning, discontinuous domain rotation or barkhausen effect during magnetization which is useful for oil-water interfacial tension reduction and viscosity of oil. The high surface charge of magnetic nanoparticles and adsorption at the rock surface is useful for wettability alteration of rocks.

  9. Cosmic rays: Space Weather Perspective

    NASA Astrophysics Data System (ADS)

    Agarwal Mishra, Rekha; Mishra, Rajesh Kumar

    The concept of Space Weather was launched before a decade to describe the short-term variations in the different form of solar ac-tivity and their effect in the near Earth environ-ment. Space weather affects the Earth's atmos-phere in many ways and through various phe-nomena. Among them, geomagnetic storms and the variability of the galactic cosmic ray flux be-long to the most important ones as for the lower atmosphere. We have performed superposed ep-och analysis using hourly neutron monitor data for three different neutron-monitoring stations of different cut off rigidity as a measure of cosmic ray intensity. In the present study for superposed epoch analysis the time of occurrence of CMEs are defined as key time (zero or epoch hour/day). It is noteworthy that the use of cosmic ray data in space weather research plays a key role for its prediction. We have studied the cosmic ray, geo-magnetic and interplanetary plasma/field data to understand the physical mechanism responsible for Forbush decrease and geomagnetic storm that can be used as a signature to forecast space weather. Keywords: Space weather, cosmic ray, geomag-netic storm, forbush decrease

  10. The effect of the geomagnetic field on cosmic ray energy estimates and large scale anisotropy searches on data from the Pierre Auger Observatory

    NASA Astrophysics Data System (ADS)

    Pierre Auger Collaboration; Abreu, P.; Aglietta, M.; Ahn, E. J.; Albuquerque, I. F. M.; Allard, D.; Allekotte, I.; Allen, J.; Allison, P.; Alvarez Castillo, J.; Alvarez-Muñiz, J.; Ambrosio, M.; Aminaei, A.; Anchordoqui, L.; Andringa, S.; Antičić, T.; Anzalone, A.; Aramo, C.; Arganda, E.; Arqueros, F.; Asorey, H.; Assis, P.; Aublin, J.; Ave, M.; Avenier, M.; Avila, G.; Bäcker, T.; Balzer, M.; Barber, K. B.; Barbosa, A. F.; Bardenet, R.; Barroso, S. L. C.; Baughman, B.; Bäuml, J.; Beatty, J. J.; Becker, B. R.; Becker, K. H.; Bellétoile, A.; Bellido, J. A.; BenZvi, S.; Berat, C.; Bertou, X.; Biermann, P. L.; Billoir, P.; Blanco, F.; Blanco, M.; Bleve, C.; Blümer, H.; Boháčová, M.; Boncioli, D.; Bonifazi, C.; Bonino, R.; Borodai, N.; Brack, J.; Brogueira, P.; Brown, W. C.; Bruijn, R.; Buchholz, P.; Bueno, A.; Burton, R. E.; Caballero-Mora, K. S.; Caramete, L.; Caruso, R.; Castellina, A.; Catalano, O.; Cataldi, G.; Cazon, L.; Cester, R.; Chauvin, J.; Cheng, S. H.; Chiavassa, A.; Chinellato, J. A.; Chou, A.; Chudoba, J.; Clay, R. W.; Coluccia, M. R.; Conceição, R.; Contreras, F.; Cook, H.; Cooper, M. J.; Coppens, J.; Cordier, A.; Coutu, S.; Covault, C. E.; Creusot, A.; Criss, A.; Cronin, J.; Curutiu, A.; Dagoret-Campagne, S.; Dallier, R.; Dasso, S.; Daumiller, K.; Dawson, B. R.; de Almeida, R. M.; De Domenico, M.; De Donato, C.; de Jong, S. J.; De La Vega, G.; de Mello Junior, W. J. M.; de Mello Neto, J. R. T.; De Mitri, I.; de Souza, V.; de Vries, K. D.; Decerprit, G.; del Peral, L.; del Río, M.; Deligny, O.; Dembinski, H.; Dhital, N.; Di Giulio, C.; Diaz, J. C.; Díaz Castro, M. L.; Diep, P. N.; Dobrigkeit, C.; Docters, W.; D'Olivo, J. C.; Dong, P. N.; Dorofeev, A.; dos Anjos, J. C.; Dova, M. T.; D'Urso, D.; Dutan, I.; Ebr, J.; Engel, R.; Erdmann, M.; Escobar, C. O.; Espadanal, J.; Etchegoyen, A.; Facal San Luis, P.; Fajardo Tapia, I.; Falcke, H.; Farrar, G.; Fauth, A. C.; Fazzini, N.; Ferguson, A. P.; Ferrero, A.; Fick, B.; Filevich, A.; Filipčič, A.; Fliescher, S.; Fracchiolla, C. E.; Fraenkel, E. D.; Fröhlich, U.; Fuchs, B.; Gaior, R.; Gamarra, R. F.; Gambetta, S.; García, B.; García Gámez, D.; Garcia-Pinto, D.; Gascon, A.; Gemmeke, H.; Gesterling, K.; Ghia, P. L.; Giaccari, U.; Giller, M.; Glass, H.; Gold, M. S.; Golup, G.; Gomez Albarracin, F.; Gómez Berisso, M.; Gonçalves, P.; Gonzalez, D.; Gonzalez, J. G.; Gookin, B.; Góra, D.; Gorgi, A.; Gouffon, P.; Gozzini, S. R.; Grashorn, E.; Grebe, S.; Griffith, N.; Grigat, M.; Grillo, A. F.; Guardincerri, Y.; Guarino, F.; Guedes, G. P.; Guzman, A.; Hague, J. D.; Hansen, P.; Harari, D.; Harmsma, S.; Harrison, T. A.; Harton, J. L.; Haungs, A.; Hebbeker, T.; Heck, D.; Herve, A. E.; Hojvat, C.; Hollon, N.; Holmes, V. C.; Homola, P.; Hörandel, J. R.; Horneffer, A.; Horvath, P.; Hrabovský, M.; Huege, T.; Insolia, A.; Ionita, F.; Italiano, A.; Jarne, C.; Jiraskova, S.; Josebachuili, M.; Kadija, K.; Kampert, K. H.; Karhan, P.; Kasper, P.; Kégl, B.; Keilhauer, B.; Keivani, A.; Kelley, J. L.; Kemp, E.; Kieckhafer, R. M.; Klages, H. O.; Kleifges, M.; Kleinfeller, J.; Knapp, J.; Koang, D.-H.; Kotera, K.; Krohm, N.; Krömer, O.; Kruppke-Hansen, D.; Kuehn, F.; Kuempel, D.; Kulbartz, J. K.; Kunka, N.; La Rosa, G.; Lachaud, C.; Lautridou, P.; Leão, M. S. A. B.; Lebrun, D.; Lebrun, P.; Leigui de Oliveira, M. A.; Lemiere, A.; Letessier-Selvon, A.; Lhenry-Yvon, I.; Link, K.; López, R.; Lopez Agüera, A.; Louedec, K.; Lozano Bahilo, J.; Lu, L.; Lucero, A.; Ludwig, M.; Lyberis, H.; Maccarone, M. C.; Macolino, C.; Maldera, S.; Mandat, D.; Mantsch, P.; Mariazzi, A. G.; Marin, J.; Marin, V.; Maris, I. C.; Marquez Falcon, H. R.; Marsella, G.; Martello, D.; Martin, L.; Martinez, H.; Martínez Bravo, O.; Mathes, H. J.; Matthews, J.; Matthews, J. A. J.; Matthiae, G.; Maurizio, D.; Mazur, P. O.; Medina-Tanco, G.; Melissas, M.; Melo, D.; Menichetti, E.; Menshikov, A.; Mertsch, P.; Meurer, C.; Mićanović, S.; Micheletti, M. I.; Miller, W.; Miramonti, L.; Molina-Bueno, L.; Mollerach, S.; Monasor, M.; Monnier Ragaigne, D.; Montanet, F.; Morales, B.; Morello, C.; Moreno, E.; Moreno, J. C.; Morris, C.; Mostafá, M.; Moura, C. A.; Mueller, S.; Muller, M. A.; Müller, G.; Münchmeyer, M.; Mussa, R.; Navarra, G.; Navarro, J. L.; Navas, S.; Necesal, P.; Nellen, L.; Nelles, A.; Neuser, J.; Nhung, P. T.; Niemietz, L.; Nierstenhoefer, N.; Nitz, D.; Nosek, D.; Nožka, L.; Nyklicek, M.; Oehlschläger, J.; Olinto, A.; Oliva, P.; Olmos-Gilbaja, V. M.; Ortiz, M.; Pacheco, N.; Pakk Selmi-Dei, D.; Palatka, M.; Pallotta, J.; Palmieri, N.; Parente, G.; Parizot, E.; Parra, A.; Parsons, R. D.; Pastor, S.; Paul, T.; Pech, M.; Pękala, J.; Pelayo, R.; Pepe, I. M.; Perrone, L.; Pesce, R.; Petermann, E.; Petrera, S.; Petrinca, P.; Petrolini, A.; Petrov, Y.; Petrovic, J.; Pfendner, C.; Phan, N.; Piegaia, R.; Pierog, T.; Pieroni, P.; Pimenta, M.; Pirronello, V.; Platino, M.; Ponce, V. H.; Pontz, M.; Privitera, P.; Prouza, M.; Quel, E. J.; Querchfeld, S.; Rautenberg, J.; Ravel, O.; Ravignani, D.; Revenu, B.; Ridky, J.; Riggi, S.; Risse, M.; Ristori, P.; Rivera, H.; Rizi, V.; Roberts, J.; Robledo, C.; Rodrigues de Carvalho, W.; Rodriguez, G.; Rodriguez Martino, J.; Rodriguez Rojo, J.; Rodriguez-Cabo, I.; Rodríguez-Frías, M. D.; Ros, G.; Rosado, J.; Rossler, T.; Roth, M.; Rouillé-d'Orfeuil, B.; Roulet, E.; Rovero, A. C.; Rühle, C.; Salamida, F.; Salazar, H.; Salesa Greus, F.; Salina, G.; Sánchez, F.; Santo, C. E.; Santos, E.; Santos, E. M.; Sarazin, F.; Sarkar, B.; Sarkar, S.; Sato, R.; Scharf, N.; Scherini, V.; Schieler, H.; Schiffer, P.; Schmidt, A.; Schmidt, F.; Scholten, O.; Schoorlemmer, H.; Schovancova, J.; Schovánek, P.; Schröder, F.; Schulte, S.; Schuster, D.; Sciutto, S. J.; Scuderi, M.; Segreto, A.; Settimo, M.; Shadkam, A.; Shellard, R. C.; Sidelnik, I.; Sigl, G.; Silva Lopez, H. H.; Śacute; Smiałkowski, A.; Šmída, R.; Snow, G. R.; Sommers, P.; Sorokin, J.; Spinka, H.; Squartini, R.; Stanic, S.; Stapleton, J.; Stasielak, J.; Stephan, M.; Strazzeri, E.; Stutz, A.; Suarez, F.; Suomijärvi, T.; Supanitsky, A. D.; Šuša, T.; Sutherland, M. S.; Swain, J.; Szadkowski, Z.; Szuba, M.; Tamashiro, A.; Tapia, A.; Tartare, M.; Taşąu, O.; Tavera Ruiz, C. G.; Tcaciuc, R.; Tegolo, D.; Thao, N. T.; Thomas, D.; Tiffenberg, J.; Timmermans, C.; Tiwari, D. K.; Tkaczyk, W.; Todero Peixoto, C. J.; Tomé, B.; Tonachini, A.; Travnicek, P.; Tridapalli, D. B.; Tristram, G.; Trovato, E.; Tueros, M.; Ulrich, R.; Unger, M.; Urban, M.; Valdés Galicia, J. F.; Valiño, I.; Valore, L.; van den Berg, A. M.; Varela, E.; Vargas Cárdenas, B.; Vázquez, J. R.; Vázquez, R. A.; Veberič, D.; Verzi, V.; Vicha, J.; Videla, M.; Villaseñor, L.; Wahlberg, H.; Wahrlich, P.; Wainberg, O.; Walz, D.; Warner, D.; Watson, A. A.; Weber, M.; Weidenhaupt, K.; Weindl, A.; Westerhoff, S.; Whelan, B. J.; Wieczorek, G.; Wiencke, L.; Wilczyńska, B.; Wilczyński, H.; Will, M.; Williams, C.; Winchen, T.; Winnick, M. G.; Wommer, M.; Wundheiler, B.; Yamamoto, T.; Yapici, T.; Younk, P.; Yuan, G.; Yushkov, A.; Zamorano, B.; Zas, E.; Zavrtanik, D.; Zavrtanik, M.; Zaw, I.; Zepeda, A.; Zimbres Silva, M.; Ziolkowski, M.

    2011-11-01

    We present a comprehensive study of the influence of the geomagnetic field on the energy estimation of extensive air showers with a zenith angle smaller than 60°, detected at the Pierre Auger Observatory. The geomagnetic field induces an azimuthal modulation of the estimated energy of cosmic rays up to the ~ 2% level at large zenith angles. We present a method to account for this modulation of the reconstructed energy. We analyse the effect of the modulation on large scale anisotropy searches in the arrival direction distributions of cosmic rays. At a given energy, the geomagnetic effect is shown to induce a pseudo-dipolar pattern at the percent level in the declination distribution that needs to be accounted for.

  11. Effect of grain size on the domain structures and electromechanical responses of ferroelectric polycrystal

    NASA Astrophysics Data System (ADS)

    Li, Xinkai; Wang, Jie

    2017-01-01

    The effect of grain size on the domain structures and electromechanical responses of ferroelectric polycrystals is investigated by a phase field model. The phase field simulations show that the different types of domains in different size of grains play an important role in the size-dependent properties of ferroelectric polycrystals. It is found that the remnant polarization, coercive field and dielectric coefficient increase monotonously with the increase of grain size. However, the piezoelectric coefficient increases first and then decreases as the grain size increases. The decrease of vortex domains is responsible for the increase of piezoelectric coefficient in the range of small grain size, the decrease of 90° domain walls results in the decrease of piezoelectric coefficient in the range of large grain size. In addition, different domain structures in different size of grains have also great influence on the mechanical depolarization of the ferroelectric polycrystals subjected to a compressive stress.

  12. Cosmic electrons. [literature review

    NASA Technical Reports Server (NTRS)

    Ramaty, R.

    1974-01-01

    The published literature on cosmic electrons is summarized. The primary and secondary sources of cosmic electrons are discussed, and the propagation of the electrons in the interstellar medium is studied with respect to energy loss mechanisms, age distributions, and spectral modifications during flight. Various portions of the electron and positron spectra are then considered in relation to problems of astrophysics. New information is presented on such topics as the origin of low-energy positrons, the decay kinematics of the pi-mu-e process, the application of age distributions for nuclear cosmic rays to cosmic electrons, and the possibility of nonidentical sources for cosmic electrons and protons.

  13. Stratospheric Sudden Warming Effects on the Ionospheric Migrating Tides during 2008-2010 observed by FORMOSAT-3/COSMIC

    NASA Astrophysics Data System (ADS)

    Lin, J.; Lin, C.; Chang, L. C.; Liu, H.; Chen, W.; Chen, C.; Liu, J. G.

    2013-12-01

    In this paper, ionospheric electron densities obtained from radio occultation soundings of FORMOSAT-3/COSMIC are decomposed into their various constituent tidal components for studying the stratospheric sudden warming (SSW) effects on the ionosphere during 2008-2010. The tidal analysis indicates that the amplitudes of the zonal mean and major migrating tidal components (DW1, SW2 and TW3) decrease around the time of the SSW, with phase/time shifts in the daily time of maximum around EIA and middle latitudes. Meanwhile consistent enhancements of the SW2 and nonmigrating SW1 tides are seen after the stratospheric temperature increase. In addition to the amplitude changes of the tidal components, well matched phase shifts of the ionospheric migrating tides and the stratospheric temperatures are found for the three SSW events, suggesting a good indicator of the ionospheric response. Although the conditions of the planetary waves and the mean winds in the middle atmosphere region during the 2008-2010 SSW events may be different, similar variations of the ionospheric tidal components and their associated phase shifts are found. Futher, these ionospheric responses will be compared with realistic simulations of Thermosphere-Ionosphere-Mesophere-Electrodynamics General Circulation Model (TIME-GCM) by nudging Modern-Era Retrospective analysis for Research and Applications (MERRA) data.

  14. Cosmic Infrared Background From Population III Stars and Its Effect on Spectra of High-z Gamma-Ray Bursts

    NASA Technical Reports Server (NTRS)

    Kashlinsky, A.

    2005-01-01

    We discuss the contribution of Population III stars to the near-IR (NIR) cosmic infrared background (CIB) and its effect on spectra of high-z, high-energy gamma-ray bursts (GRBs) and other sources. It is shown that if Population III is composed of massive stars, the claimed NIR CIB excess will be reproduced if only approx. 4% plus or minus 2% of all baryons went through these stars. Regardless of the precise amount of the NIR CIB due to them, they likely left enough photons to provide a large optical depth for high-energy photons from distant GRBs. Observations of such GRBs are expected following the planned launch of NASA's GLAST mission. Detecting such damping in the spectra of high-z GRBs will then provide important information on the emissions from the Population III epoch, and the location of this cutoff may serve as an indicator of the GRBs' redshifts. We also point out the difficulty of unambiguously detecting the CIB part originating from Population III in spectra of low-z blazars.

  15. Accounting for baryonic effects in cosmic shear tomography: determining a minimal set of nuisance parameters using PCA

    NASA Astrophysics Data System (ADS)

    Eifler, Tim; Krause, Elisabeth; Dodelson, Scott; Zentner, Andrew R.; Hearin, Andrew P.; Gnedin, Nickolay Y.

    2015-12-01

    Systematic uncertainties that have been subdominant in past large-scale structure (LSS) surveys are likely to exceed statistical uncertainties of current and future LSS data sets, potentially limiting the extraction of cosmological information. Here we present a general framework (Principal Component Analysis - PCA - marginalization) to consistently incorporate systematic effects into a likelihood analysis. This technique naturally accounts for degeneracies between nuisance parameters and can substantially reduce the dimension of the parameter space that needs to be sampled. As a practical application, we apply PCA marginalization to account for baryonic physics as an uncertainty in cosmic shear tomography. Specifically, we use COSMOLIKE to run simulated likelihood analyses on three independent sets of numerical simulations, each covering a wide range of baryonic scenarios differing in cooling, star formation, and feedback mechanisms. We simulate a Stage III (Dark Energy Survey) and Stage IV (Large Synoptic Survey Telescope/Euclid) survey and find a substantial bias in cosmological constraints if baryonic physics is not accounted for. We then show that PCA marginalization (employing at most three to four nuisance parameters) removes this bias. Our study demonstrates that it is possible to obtain robust, precise constraints on the dark energy equation of state even in the presence of large levels of systematic uncertainty in astrophysical processes. We conclude that the PCA marginalization technique is a powerful, general tool for addressing many of the challenges facing the precision cosmology programme.

  16. Accounting for baryonic effects in cosmic shear tomography: Determining a minimal set of nuisance parameters using PCA

    SciTech Connect

    Eifler, Tim; Krause, Elisabeth; Dodelson, Scott; Zentner, Andrew; Hearin, Andrew; Gnedin, Nickolay

    2014-05-28

    Systematic uncertainties that have been subdominant in past large-scale structure (LSS) surveys are likely to exceed statistical uncertainties of current and future LSS data sets, potentially limiting the extraction of cosmological information. Here we present a general framework (PCA marginalization) to consistently incorporate systematic effects into a likelihood analysis. This technique naturally accounts for degeneracies between nuisance parameters and can substantially reduce the dimension of the parameter space that needs to be sampled. As a practical application, we apply PCA marginalization to account for baryonic physics as an uncertainty in cosmic shear tomography. Specifically, we use CosmoLike to run simulated likelihood analyses on three independent sets of numerical simulations, each covering a wide range of baryonic scenarios differing in cooling, star formation, and feedback mechanisms. We simulate a Stage III (Dark Energy Survey) and Stage IV (Large Synoptic Survey Telescope/Euclid) survey and find a substantial bias in cosmological constraints if baryonic physics is not accounted for. We then show that PCA marginalization (employing at most 3 to 4 nuisance parameters) removes this bias. Our study demonstrates that it is possible to obtain robust, precise constraints on the dark energy equation of state even in the presence of large levels of systematic uncertainty in astrophysical processes. We conclude that the PCA marginalization technique is a powerful, general tool for addressing many of the challenges facing the precision cosmology program.

  17. Thermoelectric effect across the metal-insulator domain walls in VO2 microbeams.

    PubMed

    Cao, J; Fan, W; Zheng, H; Wu, J

    2009-12-01

    We report on measurements of Seebeck effect in single-crystal VO(2) microbeams across their metal-insulator phase transition. One-dimensionally aligned metal-insulator domain walls were reversibly created and eliminated along single VO(2) beams by varying temperature, which allows for accurate extraction of the net contribution to the Seebeck effect from these domain walls. We observed significantly lower Seebeck coefficient in the metal-insulator coexisting regime than predicted by a linear combination of contributions from the insulator and metal domains. This indicates that the net contribution of the domain walls has an opposite sign from that of the insulator and metal phases separately. Possible origins that may be responsible for this unexpected effect were discussed in the context of complications in this correlated electron material.

  18. Barometric effect of the neutron component of cosmic rays with consideration for wind effect at the Antarctic station Mirny and station Mt. Hermon in Israel

    NASA Astrophysics Data System (ADS)

    Lev, Dorman

    2016-07-01

    Estimation of barometric coefficient for neutron component of cosmic rays was performed for Antarctic station Mirny and Mt. Hermon in Israel taking into account effect of dynamic pressure caused by wind in the atmosphere. Hourly data of continue monitoring of neutron component and data of the local meteo-station have been used for the period 2007-2014. Wind velocity at the observatory Mirny reaches 20-40 m/s in winter that corresponds to dynamic pressure of 5-6 mb and leads to the error of 5% in variations of neutron component because of dynamic effect in the atmosphere. The results are important for high latitude and high mountain detectors, where effect Bernoulli may be significant.

  19. Cosmic Complexity

    NASA Technical Reports Server (NTRS)

    Mather, John C.

    2012-01-01

    neutrons, liberating a little energy and creating complexity. Then, the expanding universe cooled some more, and neutrons and protons, no longer kept apart by immense temperatures, found themselves unstable and formed helium nuclei. Then, a little more cooling, and atomic nuclei and electrons were no longer kept apart, and the universe became transparent. Then a little more cooling, and the next instability began: gravitation pulled matter together across cosmic distances to form stars and galaxies. This instability is described as a "negative heat capadty" in which extracting energy from a gravitating system makes it hotter -- clearly the 2nd law of thermodynamics does not apply here! (This is the physicist's part of the answer to e e cummings' question: what is the wonder that's keeping the stars apart?) Then, the next instability is that hydrogen and helium nuclei can fuse together to release energy and make stars burn for billions of years. And then at the end of the fuel source, stars become unstable and explode and liberate the chemical elements back into space. And because of that, on planets like Earth, sustained energy flows support the development of additional instabilities and all kinds of complex patterns. Gravitational instability pulls the densest materials into the core of the Earth, leaving a thin skin of water and air, and makes the interior churn incessantly as heat flows outwards. And the heat from the sun, received mostly near the equator and flowing towards the poles, supports the complex atmospheric and oceanic circulations. And because or that, the physical Earth is full of natural chemical laboratories, concentrating elements here, mixing them there, raising and lowering temperatures, ceaselessly experimenting with uncountable events where new instabilities can arise. At least one of them was the new experiment called life. Now that we know that there are at least as many planets as there are stars, it is hard to imagine that nature's ceasess

  20. Cosmic Complexity

    NASA Technical Reports Server (NTRS)

    Mather, John C.

    2012-01-01

    neutrons, liberating a little energy and creating complexity. Then, the expanding universe cooled some more, and neutrons and protons, no longer kept apart by immense temperatures, found themselves unstable and formed helium nuclei. Then, a little more cooling, and atomic nuclei and electrons were no longer kept apart, and the universe became transparent. Then a little more cooling, and the next instability began: gravitation pulled matter together across cosmic distances to form stars and galaxies. This instability is described as a "negative heat capadty" in which extracting energy from a gravitating system makes it hotter -- clearly the 2nd law of thermodynamics does not apply here! (This is the physicist's part of the answer to e e cummings' question: what is the wonder that's keeping the stars apart?) Then, the next instability is that hydrogen and helium nuclei can fuse together to release energy and make stars burn for billions of years. And then at the end of the fuel source, stars become unstable and explode and liberate the chemical elements back into space. And because of that, on planets like Earth, sustained energy flows support the development of additional instabilities and all kinds of complex patterns. Gravitational instability pulls the densest materials into the core of the Earth, leaving a thin skin of water and air, and makes the interior churn incessantly as heat flows outwards. And the heat from the sun, received mostly near the equator and flowing towards the poles, supports the complex atmospheric and oceanic circulations. And because or that, the physical Earth is full of natural chemical laboratories, concentrating elements here, mixing them there, raising and lowering temperatures, ceaselessly experimenting with uncountable events where new instabilities can arise. At least one of them was the new experiment called life. Now that we know that there are at least as many planets as there are stars, it is hard to imagine that nature's ceasess

  1. The effect of the geomagnetic field on cosmic ray energy estimates and large scale anisotropy searches on data from the Pierre Auger Observatory

    SciTech Connect

    Abreu, P.; Aglietta, M.; Ahn, E.J.; Albuquerque, I.F.M.; Allard, D.; Allekotte, I.; Allen, J.; Allison, P.; Alvarez Castillo, J.; Alvarez-Muniz, J.; Ambrosio, M.; /Naples U. /INFN, Naples /Nijmegen U., IMAPP

    2011-11-01

    We present a comprehensive study of the influence of the geomagnetic field on the energy estimation of extensive air showers with a zenith angle smaller than 60{sup o}, detected at the Pierre Auger Observatory. The geomagnetic field induces an azimuthal modulation of the estimated energy of cosmic rays up to the {approx} 2% level at large zenith angles. We present a method to account for this modulation of the reconstructed energy. We analyse the effect of the modulation on large scale anisotropy searches in the arrival direction distributions of cosmic rays. At a given energy, the geomagnetic effect is shown to induce a pseudo-dipolar pattern at the percent level in the declination distribution that needs to be accounted for. In this work, we have identified and quantified a systematic uncertainty affecting the energy determination of cosmic rays detected by the surface detector array of the Pierre Auger Observatory. This systematic uncertainty, induced by the influence of the geomagnetic field on the shower development, has a strength which depends on both the zenith and the azimuthal angles. Consequently, we have shown that it induces distortions of the estimated cosmic ray event rate at a given energy at the percent level in both the azimuthal and the declination distributions, the latter of which mimics an almost dipolar pattern. We have also shown that the induced distortions are already at the level of the statistical uncertainties for a number of events N {approx_equal} 32 000 (we note that the full Auger surface detector array collects about 6500 events per year with energies above 3 EeV). Accounting for these effects is thus essential with regard to the correct interpretation of large scale anisotropy measurements taking explicitly profit from the declination distribution.

  2. Biological Effects of Nuclear Explosions (BENE) Domain Guide

    DTIC Science & Technology

    2012-09-01

    irradiated soil), and the effectiveness of radiation on biological warfare agents. Operation SANDSTONE (Table 1.2) assessed the effects of ionizing...radiation on a variety of seeds, insects , and bacteria. Operation GREENHOUSE (Table 1.3) assessed the effects of nuclear radiation on mice, pigs... irradiated animals as well as dosimeters. Operation IVY (Table 1.4) did surveys of plant and animal specimens before and after Test Mike to determine

  3. Effects of Atomistic Domain Size on Hybrid Lattice Boltzmann-Molecular Dynamics Simulations of Dense Fluids

    NASA Astrophysics Data System (ADS)

    Dupuis, A.; Koumoutsakos, P.

    We present a convergence study for a hybrid Lattice Boltzmann-Molecular Dynamics model for the simulation of dense liquids. Time and length scales are decoupled by using an iterative Schwarz domain decomposition algorithm. The velocity field from the atomistic domain is introduced as forcing terms to the Lattice Boltzmann model of the continuum while the mean field of the continuum imposes mean field conditions for the atomistic domain. In the present paper we investigate the effect of varying the size of the atomistic subdomain in simulations of two dimensional flows of liquid argon past carbon nanotubes and assess the efficiency of the method.

  4. Footprint Characteristics of Cosmic-Ray Neutron Sensors for Soil Moisture Monitoring

    NASA Astrophysics Data System (ADS)

    Schrön, Martin; Köhli, Markus; Zreda, Marek; Dietrich, Peter; Zacharias, Steffen

    2015-04-01

    Cosmic-ray neutron sensing is a unique and an increasingly accepted method to monitor the effective soil water content at the field scale. The technology is famous for its low maintenance, non-invasiveness, continuous measurement, and most importantly, for its large footprint. Being more representative than point data and finer resolved than remote-sensing products, cosmic-ray neutron derived soil moisture products provide unrivaled advantage for mesoscale hydrologic and land surface models. The method takes advantage of neutrons induced by cosmic radiation which are extraordinarily sensitive to hydrogen and behave like a hot gas. Information about nearby water sources are quickly mixed in a domain of tens of hectares in air. Since experimental determination of the actual spatial extent is hardly possible, scientists have applied numerical models to address the footprint characteristics. We have revisited previous neutron transport simulations and present a modified conceptual design and refined physical assumptions. Our revised study reveals new insights into probing distance and water sensitivity of detected neutrons under various environmental conditions. These results sharpen the range of interpretation concerning the spatial extent of integral soil moisture products derived from cosmic-ray neutron counts. Our findings will have important impact on calibration strategies, on scales for data assimilation and on the interpolation of soil moisture data derived from mobile cosmic-ray neutron surveys.

  5. Footprint Characteristics of Cosmic-Ray Neutron Sensing for Soil Moisture Monitoring

    NASA Astrophysics Data System (ADS)

    Schrön, M.; Köhli, M.; Zreda, M. G.; Dietrich, P.; Zacharias, S.

    2014-12-01

    Cosmic-ray neutron sensing has become an increasingly accepted and unique method to monitor the effective soil water content at the field scale. The technology is famous for its low maintenance, non-invasiveness, continuous measurement, and most importantly, for its large footprint. Being more representative than point data and finer resolved than remote-sensing products, cosmic-ray neutron derived soil moisture products provide unrivaled advantage for mesoscale hydrologic and land surface models. The method takes advantage of neutrons induced by cosmic radiation which are extraordinarily sensitive to hydrogen and behave like a hot gas. Information about nearby water sources quickly mixes a domain of tens of hectares in air. Since experimental determination of the actual spatial extent is hardly possible, scientists have applied numerical models to address the footprint characteristics. We have revisited previous neutron transport simulations and present a modified conceptual design and refined physical assumptions. Our revised study reveals new insights to energy spectra, probing distance and water sensitivity of detected neutrons under various environmental conditions. These results sharpen the range of interpretation concerning the spatial extent of integral soil moisture products derived from cosmic-ray neutron counts. Our findings will have important impact calibration strategies, on scales for data assimilation and on the interpolation of soil moisture data derived from mobile cosmic-ray neutron surveys.

  6. Effective theory of dark matter decay into monochromatic photons and its implications: Constraints from associated cosmic-ray emission

    NASA Astrophysics Data System (ADS)

    Gustafsson, Michael; Hambye, Thomas; Scarnà, Tiziana

    2013-07-01

    We show that there exists only a quite limited number of higher dimensional operators which can naturally lead to a slow decay of dark matter particles into monochromatic photons. As each of these operators inevitably induces decays into particles other than photons, we show that the γ-lines it induces are always accompanied by a continuum flux of cosmic rays. Hence constraints on cosmic-ray fluxes imply constraints on the intensity of γ-lines and vice versa. A comparison with up to date observational bounds shows the possibilities to observe or exclude cosmic rays associated to γ-line emission, so that one could better determine the properties of the DM particle, possibly discriminating between some of the operators.

  7. Investigation of Reacceleration on Cosmic Ray

    NASA Astrophysics Data System (ADS)

    Lu, Yuxi; Picot-Clemente, Nicolas; Seo, Eun-Suk

    2016-03-01

    Cosmic rays are high energy charged particles, originating from outer space, that travel at nearly the speed of light and strike the Earth from all directions. One century after the discovery of cosmic rays, their origin and propagation processes remain obscure. GALPROP is a numerical code for calculating the propagation of relativistic charged particles and the diffuse emissions produced during their propagation in the Galaxy. I performed a preliminary study using two different propagation models with the GALPROP code in order to reproduce latest cosmic-ray nuclei measurements. I analyzed multiple propagation parameters for each model, studied their effect on cosmic-ray spectra, optimized and tried a preliminary modification of the code to fit cosmic-ray data such as BESS-Polar, AMS, CREAM, etc.

  8. Cosmic rays: a review for astrobiologists.

    PubMed

    Ferrari, Franco; Szuszkiewicz, Ewa

    2009-05-01

    Cosmic rays represent one of the most fascinating research themes in modern astronomy and physics. Significant progress is being made toward an understanding of the astrophysics of the sources of cosmic rays and the physics of interactions in the ultrahigh-energy range. This is possible because several new experiments in these areas have been initiated. Cosmic rays may hold answers to a great number of fundamental questions, but they also shape our natural habitat and influence the radiation environment of our planet Earth. The importance of the study of cosmic rays has been acknowledged in many fields, including space weather science and astrobiology. Here, we concentrate on the astrobiological aspects of cosmic rays with regard to the enormous amount of new data available, some of which may, in fact, improve our knowledge about the radiation of cosmic origin on Earth. We focus on fluxes arriving at Earth and doses received, and will guide the reader through the wealth of scientific literature on cosmic rays. We have prepared a concise and self-contained source of data and recipes useful for performing interdisciplinary research in cosmic rays and their effects on life on Earth.

  9. Zipping and unzipping of cosmic string loops in collision

    SciTech Connect

    Firouzjahi, H.; Karouby, J.; Khosravi, S.; Brandenberger, R.

    2009-10-15

    In this paper the collision of two cosmic string loops is studied. After collision junctions are formed and the loops are entangled. We show that after their formation the junctions start to unzip and the loops disentangle. This analysis provides a theoretical understanding of the unzipping effect observed in numerical simulations of a network of cosmic strings with more than one type of cosmic strings. The unzipping phenomena have important effects in the evolution of cosmic string networks when junctions are formed upon collision, such as in a network of cosmic superstrings.

  10. Cosmic ray antiprotons from nearby cosmic accelerators

    NASA Astrophysics Data System (ADS)

    Joshi, Jagdish C.; Gupta, Nayantara

    2015-05-01

    The antiproton flux measured by PAMELA experiment might have originated from Galactic sources of cosmic rays. These antiprotons are expected to be produced in the interactions of cosmic ray protons and nuclei with cold protons. Gamma rays are also produced in similar interactions inside some of the cosmic accelerators. We consider a few nearby supernova remnants observed by Fermi LAT. Many of them are associated with molecular clouds. Gamma rays have been detected from these sources which most likely originate in decay of neutral pions produced in hadronic interactions. The observed gamma ray fluxes from these SNRs are used to find out their contributions to the observed diffuse cosmic ray antiproton flux near the earth.

  11. Individual domains of Tensin2 exhibit distinct subcellular localisations and migratory effects.

    PubMed

    Hafizi, Sassan; Sernstad, Emma; Swinny, Jerome D; Gomez, Maria F; Dahlbäck, Björn

    2010-01-01

    Tensins are large intracellular proteins believed to link the extracellular matrix to the cytoskeleton via integrins. Tensins are multidomain proteins consisting of homologous C1, PTPase, C2, SH2 and PTB domains. Full-length Tensin proteins can undergo cleavage inside cells, thus yielding domains in isolation that may have discrete subcellular localisations and downstream effects. We expressed different isoforms of Tensin2 and their individual domains as recombinant green fluorescent protein (GFP)-fusion constructs in DU145 human prostate cancer cells. Under fluorescence confocal microscopy, the isolated domains of Tensin2 all displayed discrete distributions throughout the cytoplasm and the nucleus. In particular, partial constructs containing the C1 domain localised preferentially to the nucleus, including the isolated C1 domain and the PTPase domain. In contrast, all three full-length isoforms of Tensin2 were present exclusively in discrete punctate bodies throughout the cytoplasm. This punctate staining showed colocalisation with the tumour suppressor protein DLC-1 as well as with actin (phalloidin). Furthermore, DU145 cells transiently expressing partial Tensin2 constructs containing the PTB domain showed an increased haptotactic migration. In addition, stimulation of renal carcinoma cells stably expressing Tensin2 by the survival factor Gas6 caused phosphorylation of its receptor Axl, but no effect on Tensin2, which was already maximally phosphorylated at time 0. In conclusion, our results indicate that differential proteolytic cleavage of Tensin2 can liberate domains with discrete localisations and functions, which has implications for the role of Tensins in cancer cell survival and motility.

  12. The effects of cosmic particle radiation on pocket mice aboard Apollo XVII: III. Dosimeter design, construction, and implantation.

    PubMed

    Winter, D L; Suri, K; D'Urso, J A; Cota, F L; Ashley, W W; Binnard, R M; Haymaker, W; Benton, E V; Cruty, M R; Zeman, W

    1975-04-01

    To detect the passage of cosmic ray particles through the heads of the pocket mice during the Apollo XVII flight, a "monitor" (dosimeter) composed of plastics was prepared and implanted under the scalp. The monitor was mounted on a platform, the undersurface of which fitted the contour of the skull. Numerous tests were run to assure that the presence of the monitor assembly beneath the scalp would be compatible with the well-being of the mice and that the capacity of the monitor to detect the traversal of cosmic ray particles would be preserved over the several weeks during which it would remain under the scalp.

  13. Effects of interplanetary magnetic clouds, interaction regions, and high-speed streams on the transient modulation of galactic cosmic rays

    NASA Astrophysics Data System (ADS)

    Singh, Y. P.; Badruddin

    2007-02-01

    Interplanetary manifestations of coronal mass ejections (CMEs) with specific plasma and field properties, called ``interplanetary magnetic clouds,'' have been observed in the heliosphere since the mid-1960s. Depending on their associated features, a set of observed magnetic clouds identified at 1 AU were grouped in four different classes using data over 4 decades: (1) interplanetary magnetic clouds moving with the ambient solar wind (MC structure), (2) magnetic clouds moving faster than the ambient solar wind and forming a shock/sheath structure of compressed plasma and field ahead of it (SMC structure), (3) magnetic clouds ``pushed'' by the high-speed streams from behind, forming an interaction region between the two (MIH structure), and (4) shock-associated magnetic clouds followed by high-speed streams (SMH structure). This classification into different groups led us to study the role, effect, and the relative importance of (1) closed field magnetic cloud structure with low field variance, (2) interplanetary shock and magnetically turbulent sheath region, (3) interaction region with large field variance, and (4) the high-speed solar wind stream coming from the open field regions, in modulating the galactic cosmic rays (GCRs). MC structures are responsible for transient decrease with fast recovery. SMC structures are responsible for fast decrease and slow recovery, MIH structures produce depression with slow decrease and slow recovery, and SMH structures are responsible for fast decrease with very slow recovery. Simultaneous variations of GCR intensity, solar plasma velocity, interplanetary magnetic field strength, and its variance led us to study the relative effectiveness of different structures as well as interplanetary plasma/field parameters. Possible role of the magnetic field, its topology, field turbulence, and the high-speed streams in influencing the amplitude and time profile of resulting decreases in GCR intensity have also been discussed.

  14. How Does Processing Affect Storage in Working Memory Tasks? Evidence for Both Domain-General and Domain-Specific Effects

    ERIC Educational Resources Information Center

    Jarrold, Christopher; Tam, Helen; Baddeley, Alan D.; Harvey, Caroline E.

    2011-01-01

    Two studies that examine whether the forgetting caused by the processing demands of working memory tasks is domain-general or domain-specific are presented. In each, separate groups of adult participants were asked to carry out either verbal or nonverbal operations on exactly the same processing materials while maintaining verbal storage items.…

  15. CREME: The 2011 Revision of the Cosmic Ray Effects on Micro-Electronics Code

    NASA Technical Reports Server (NTRS)

    Adams, James H., Jr.; Barghouty, Abdulnasser F.; Reed, Robert A.; Sierawski, Brian D.; Watts, John W., Jr.

    2012-01-01

    We describe a tool suite, CREME, which combines existing capabilities of CREME96 and CREME86 with new radiation environment models and new Monte Carlo computational capabilities for single event effects and total ionizing dose.

  16. RED SUPERGIANT STARS AS COSMIC ABUNDANCE PROBES. II. NLTE EFFECTS IN J-BAND SILICON LINES

    SciTech Connect

    Bergemann, Maria; Kudritzki, Rolf-Peter; Wuerl, Matthias; Plez, Bertrand; Davies, Ben; Gazak, Zach E-mail: Matthias.Wuerl@physik.uni-muenchen.de E-mail: zgazak@ifa.hawaii.edu E-mail: bdavies@ast.cam.ac.uk

    2013-02-20

    Medium-resolution J-band spectroscopy of individual red supergiant stars is a promising tool to investigate the chemical composition of the young stellar population in star-forming galaxies. As a continuation of recent work on iron and titanium, detailed non-LTE (NLTE) calculations are presented to investigate the influence of NLTE on the formation of silicon lines in the J-band spectra of red supergiants. Substantial effects are found resulting in significantly stronger absorption lines of neutral silicon in NLTE. As a consequence, silicon abundances determined in NLTE are significantly smaller than in local thermodynamic equilibrium (LTE) with the NLTE abundance corrections varying smoothly between -0.4 dex and -0.1 dex for effective temperatures between 3400 K and 4400 K. The effects are largest at low metallicity. The physical reasons behind the NLTE effects and the consequences for extragalactic J-band abundance studies are discussed.

  17. Effects of Working Memory Capacity and Domain Knowledge on Recall for Grocery Prices.

    PubMed

    Bermingham, Douglas; Gardner, Michael K; Woltz, Dan J

    2016-01-01

    Hambrick and Engle (2002) proposed 3 models of how domain knowledge and working memory capacity may work together to influence episodic memory: a "rich-get-richer" model, a "building blocks" model, and a "compensatory" model. Their results supported the rich-get-richer model, although later work by Hambrick and Oswald (2005) found support for a building blocks model. We investigated the effects of domain knowledge and working memory on recall of studied grocery prices. Working memory was measured with 3 simple span tasks. A contrast of realistic versus fictitious foods in the episodic memory task served as our manipulation of domain knowledge, because participants could not have domain knowledge of fictitious food prices. There was a strong effect for domain knowledge (realistic food-price pairs were easier to remember) and a moderate effect for working memory capacity (higher working memory capacity produced better recall). Furthermore, the interaction between domain knowledge and working memory produced a small but significant interaction in 1 measure of price recall. This supported the compensatory model and stands in contrast to previous research.

  18. Dual Beneficial Effect of Interloop Disulfide Bond for Single Domain Antibody Fragments*

    PubMed Central

    Govaert, Jochen; Pellis, Mireille; Deschacht, Nick; Vincke, Cécile; Conrath, Katja; Muyldermans, Serge; Saerens, Dirk

    2012-01-01

    The antigen-binding fragment of functional heavy chain antibodies (HCAbs) in camelids comprises a single domain, named the variable domain of heavy chain of HCAbs (VHH). The VHH harbors remarkable amino acid substitutions in the framework region-2 to generate an antigen-binding domain that functions in the absence of a light chain partner. The substitutions provide a more hydrophilic, hence more soluble, character to the VHH but decrease the intrinsic stability of the domain. Here we investigate the functional role of an additional hallmark of dromedary VHHs, i.e. the extra disulfide bond between the first and third antigen-binding loops. After substituting the cysteines forming this interloop cystine by all 20 amino acids, we selected and characterized several VHHs that retain antigen binding capacity. Although VHH domains can function in the absence of an interloop disulfide bond, we demonstrate that its presence constitutes a net advantage. First, the disulfide bond stabilizes the domain and counteracts the destabilization by the framework region-2 hallmark amino acids. Second, the disulfide bond rigidifies the long third antigen-binding loop, leading to a stronger antigen interaction. This dual beneficial effect explains the in vivo antibody maturation process favoring VHH domains with an interloop disulfide bond. PMID:22128183

  19. RED SUPERGIANT STARS AS COSMIC ABUNDANCE PROBES. III. NLTE EFFECTS IN J-BAND MAGNESIUM LINES

    SciTech Connect

    Bergemann, Maria; Kudritzki, Rolf-Peter; Gazak, Zach; Davies, Ben; Plez, Bertrand E-mail: kud@ifa.hawaii.edu E-mail: bdavies@ast.cam.ac.uk

    2015-05-10

    Non-local thermodynamic equilibrium (NLTE) calculations for Mg i in red supergiant stellar atmospheres are presented to investigate the importance of NLTE for the formation of Mg i lines in the NIR J-band. Recent work using medium resolution spectroscopy of atomic lines in the J-band of individual red supergiant stars has demonstrated this technique is a very promising tool for investigating the chemical composition of the young stellar population in star forming galaxies. As in previous work, where NLTE effects were studied for iron, titanium, and silicon, substantial effects are found resulting in significantly stronger Mg i absorption lines. For the quantitative spectral analysis the NLTE effects lead to magnesium abundances significantly smaller than in local thermodynamic equilibrium with the NLTE abundance corrections varying smoothly between −0.4 dex and −0.1 dex for effective temperatures between 3400 and 4400 K. We discuss the physical reasons of the NLTE effects and the consequences for extragalactic J-band abundance studies using individual red supergiants in the young massive galactic double cluster h and χ Persei.

  20. Cosmic strings: A problem or a solution

    SciTech Connect

    Bennett, D.P.; Bouchet, F.R.

    1987-10-01

    The most fundamental issue in the theory of cosmic strings is addressed by means of Numerical Simulations: the existence of a scaling solution. The resolution of this question will determine whether cosmic strings can form the basis of an attractive theory of galaxy formation or prove to be a cosmological disaster like magnetic monopoles or domain walls. After a brief discussion of our numerical technique, results are presented which, though still preliminary, offer the best support to date of this scaling hypothesis. 6 refs., 2 figs.

  1. Effect of interdomain linker length on an antagonistic folding-unfolding equilibrium between two protein domains.

    PubMed

    Cutler, Thomas A; Mills, Brandon M; Lubin, David J; Chong, Lillian T; Loh, Stewart N

    2009-02-27

    Fusion of one protein domain with another is a common event in both evolution and protein engineering experiments. When insertion is at an internal site (e.g., a surface loop or turn), as opposed to one of the termini, conformational strain can be introduced into both domains. Strain is manifested by an antagonistic folding-unfolding equilibrium between the two domains, which we previously showed can be parameterized by a coupling free-energy term (DeltaG(X)). The extent of strain is predicted to depend primarily on the ratio of the N-to-C distance of the guest protein to the distance between ends of the surface loop in the host protein. Here, we test that hypothesis by inserting ubiquitin (Ub) into the bacterial ribonuclease barnase (Bn), using peptide linkers from zero to 10 amino acids each. DeltaG(X) values are determined by measuring the extent to which Co(2+) binding to an engineered site on the Ub domain destabilizes the Bn domain. All-atom, unforced Langevin dynamics simulations are employed to gain structural insight into the mechanism of mechanically induced unfolding. Experimental and computational results find that the two domains are structurally and energetically uncoupled when linkers are long and that DeltaG(X) increases with decreasing linker length. When the linkers are fewer than two amino acids, strain is so great that one domain unfolds the other. However, the protein is able to refold as dimers and higher-order oligomers. The likely mechanism is a three-dimensional domain swap of the Bn domain, which relieves conformational strain. The simulations suggest that an effective route to mechanical unfolding begins with disruption of the hydrophobic core of Bn near the Ub insertion site.

  2. Effect of Fiber Laser Treating on Magnetic Domains in the Grain-Oriented Silicon Steel: Imaging Domains by Bitter, MFM and Kerr Microscopy

    NASA Astrophysics Data System (ADS)

    Puchý, V.; Kováč, F.; Hvizdoš, P.; Petryshynets, I.; Sopko, M.

    2016-08-01

    A magnetic domain laser scribing technique of grain-oriented 3.2% silicon steel has been investigated for the direct influencing on the magnetic domain wall. The magneto-optical Kerr effect was employed to obtain a visible contrast between antiparallel domains. The effects of laser treating on domain wall were observed. The Bitter, MFM and Kerr microscope pictures showed that domain-wall positions did not repeat precisely from cycle to cycle, particularly at high inductions, and that the average domain-wall spacing decreased with increasing density of laser scribing lines. Two phenomena have been discovered that are difficult to explain (1) that the hardness decreases with increasing laser energy and (2) that the coercivity decreases with decreasing laser energy. A semi-quantitative relationship has been found between the domain patterns and used fiber laser treating method. The behavior of patterns in an applied magnetic field is shown, and based on that a two-dimensional laser lines configuration is proposed for one of the less complicated surface patterns.

  3. The Vanderbilt Expertise Test reveals domain-general and domain-specific sex effects in object recognition.

    PubMed

    McGugin, Rankin W; Richler, Jennifer J; Herzmann, Grit; Speegle, Magen; Gauthier, Isabel

    2012-09-15

    Individual differences in face recognition are often contrasted with differences in object recognition using a single object category. Likewise, individual differences in perceptual expertise for a given object domain have typically been measured relative to only a single category baseline. In Experiment 1, we present a new test of object recognition, the Vanderbilt Expertise Test (VET), which is comparable in methods to the Cambridge Face Memory Task (CFMT) but uses eight different object categories. Principal component analysis reveals that the underlying structure of the VET can be largely explained by two independent factors, which demonstrate good reliability and capture interesting sex differences inherent in the VET structure. In Experiment 2, we show how the VET can be used to separate domain-specific from domain-general contributions to a standard measure of perceptual expertise. While domain-specific contributions are found for car matching for both men and women and for plane matching in men, women in this sample appear to use more domain-general strategies to match planes. In Experiment 3, we use the VET to demonstrate that holistic processing of faces predicts face recognition independently of general object recognition ability, which has a sex-specific contribution to face recognition. Overall, the results suggest that the VET is a reliable and valid measure of object recognition abilities and can measure both domain-general skills and domain-specific expertise, which were both found to depend on the sex of observers.

  4. A selection effect boosting the contribution from rapidly spinning black holes to the cosmic X-ray background

    NASA Astrophysics Data System (ADS)

    Vasudevan, R. V.; Fabian, A. C.; Reynolds, C. S.; Aird, J.; Dauser, T.; Gallo, L. C.

    2016-05-01

    The cosmic X-ray background (CXB) is the total emission from past accretion activity on to supermassive black holes in active galactic nuclei (AGN) and peaks in the hard X-ray band (30 keV). In this paper, we identify a significant selection effect operating on the CXB and flux-limited AGN surveys, and outline how they must depend heavily on the spin distribution of black holes. We show that, due to the higher radiative efficiency of rapidly spinning black holes, they will be over-represented in the X-ray background, and therefore could be a dominant contributor to the CXB. Using a simple bimodal spin distribution, we demonstrate that only 15 per cent maximally spinning AGN can produce 50 per cent of the CXB. We also illustrate that invoking a small population of maximally spinning black holes in CXB synthesis models can reproduce the CXB peak without requiring large numbers of Compton-thick AGN. The spin bias is even more pronounced for flux-limited surveys: 7 per cent of sources with maximally spinning black holes can produce half of the source counts. The detectability for maximum spin black holes can be further boosted in hard (>10 keV) X-rays by up to ˜60 per cent due to pronounced ionized reflection, reducing the percentage of maximally spinning black holes required to produce half of the CXB or survey number counts further. A host of observations are consistent with an over-representation of high-spin black holes. Future NuSTAR and ASTRO-H hard X-ray surveys will provide the best constraints on the role of spin within the AGN population.

  5. Magneto-optical Kerr effect susceptometer for the analysis of magnetic domain wall dynamics.

    PubMed

    Kataja, Mikko; van Dijken, Sebastiaan

    2011-10-01

    Domain wall dynamics in thin magnetic films with perpendicular and in-plane anisotropy is studied using a novel magneto-optical Kerr effect susceptometery method. The method allows for measurements of domain wall motion under ac field excitation and the analysis of dynamic modes as a function of driving frequency and magnetic field amplitude. Domain wall dynamics in the perpendicular anisotropy system, a Co/Pt multilayer, is characterized by thermally activated creep motion. For this dynamic mode, a polydispersivity exponent of β = 0.50 ± 0.03 is derived at small excitation energy, which is in excellent agreement with theoretical models. The dynamics of the other system, a Co wire with transverse uniaxial anisotropy, is dominated by viscous slide motion in a regular magnetic stripe pattern. Analytical expressions are derived for this magnetic configuration and by using these expressions, accurate values for the depinning field and the domain wall mobility are extracted from the susceptibility measurements.

  6. Non-Linear Effects of Self Generated Alfven Waves in Oblique Shocks and Cosmic Ray Acceleration Efficiency

    NASA Astrophysics Data System (ADS)

    Medina-Tanco, G. A.; Opher, R.

    1990-11-01

    RESUMEN. Se presentan resultados numericos para un modelo hidrodinamico de cuatro componentes (plasma de fondo, particulas energeticas, ondas de Alfven autogeneradas y campo magnetico) para choques oblicuos. ABSTRACT. Numerical results of a four component hydrodynamic model (background plasma, energetic particles, self-generated Alfven waves and magnetic field) for oblique shocks are presented. Keq wo't : COSMIC RAY-GENERAL - PLASMAS - SHOCK WAVES

  7. The Cosmic Background Explorer.

    ERIC Educational Resources Information Center

    Gulkis, Samuel; And Others

    1990-01-01

    Outlines the Cosmic Background Explorer (COBE) mission to measure celestial radiation. Describes the instruments used and experiments involving differential microwave radiometers, and a far infrared absolute spectrophotometer. (YP)

  8. The cosmic neutrino background

    NASA Technical Reports Server (NTRS)

    Dar, Arnon

    1991-01-01

    The cosmic neutrino background is expected to consist of relic neutrinos from the big bang, of neutrinos produced during nuclear burning in stars, of neutrinos released by gravitational stellar collapse, and of neutrinos produced by cosmic ray interactions with matter and radiation in the interstellar and intergalactic medium. Formation of baryonic dark matter in the early universe, matter-antimatter annihilation in a baryonic symmetric universe, and dark matter annihilation could have also contributed significantly to the cosmic neutrino background. The purpose of this paper is to review the properties of these cosmic neutrino backgrounds, the indirect evidence for their existence, and the prospects for their detection.

  9. Cosmic rays and other space weather effects influenced on satellite operation, technologies, biosphere and people health

    NASA Astrophysics Data System (ADS)

    Lev, Dorman

    2016-07-01

    Satellite anomalies (or malfunctions), including total distortion of electronics and loose of some satellites cost for Insurance Companies billions dollars per year. During especially active periods the probability of big satellite anomalies and their loosing increased very much. Now, when a great number of civil and military satellites are continuously worked for our practice life, the problem of satellite anomalies became very important. Many years ago about half of satellite anomalies were caused by technical reasons (for example, for Russian satellites Kosmos), but with time with increasing of production quality, this part became smaller and smaller. The other part, which now is dominated, caused by different space weather effects (energetic particles of CR and generated/trapped in the magnetosphere, and so on). We consider only satellite anomalies not caused by technical reasons: the total number of such anomalies about 6000 events, and separately for high and low altitude orbit satellites (5000 and about 800 events, correspondingly for high and low altitude satellites). No relation was found between low and high altitude satellite anomalies. Daily numbers of satellite anomalies, averaged by a superposed epoch method around sudden storm commencements and solar proton event onsets for high (>1500 km) and low (<1500 km) altitude orbits revealed a big difference in a behavior. Satellites were divided on several groups according to the orbital characteristics (altitude and inclination). The relation of satellite anomalies to the environmental parameters was found to be different for various orbits that should be taken into account under developing of the anomaly frequency models and forecasting. We consider also influence of CR on frequency of gene mutations and evolution of biosphere (we show that if it will be no CR, the Earth's civilization will be start only after milliards years later, what will be too late), CR role in thunderstorm phenomena and discharges

  10. Effective field theory of cosmic acceleration: Constraining dark energy with CMB data

    NASA Astrophysics Data System (ADS)

    Raveri, Marco; Hu, Bin; Frusciante, Noemi; Silvestri, Alessandra

    2014-08-01

    We introduce EFTCAMB/EFTCosmoMC as publicly available patches to the commonly used camb/CosmoMC codes. We briefly describe the structure of the codes, their applicability and main features. To illustrate the use of these patches, we obtain constraints on parametrized pure effective field theory and designer f(R) models, both on ΛCDM and wCDM background expansion histories, using data from Planck temperature and lensing potential spectra, WMAP low-ℓ polarization spectra (WP), and baryon acoustic oscillations (BAO). Upon inspecting the theoretical stability of the models on the given background, we find nontrivial parameter spaces that we translate into viability priors. We use different combinations of data sets to show their individual effects on cosmological and model parameters. Our data analysis results show that, depending on the adopted data sets, in the wCDM background case these viability priors could dominate the marginalized posterior distributions. Interestingly, with Planck +WP+BAO+lensing data, in f(R) gravity models, we get very strong constraints on the constant dark energy equation of state, w0∈(-1,-0.9997) (95% C.L.).

  11. Cosmic life

    NASA Astrophysics Data System (ADS)

    Friedman, H.

    1980-01-01

    The existence and detection of extraterrestrial life are discussed. The evolution of life on earth is not considered possible if earth were 5% closer (runaway greenhouse effect) or 1% farther (runaway glaciation) from the sun, or if the sun were slightly more or less massive or hot. The Space Telescope and a possible interferometer search at infrared wavelengths, which offers a 100,000 times advantage over the visible in the ratio of planetary to stellar power, are proposed to help detect planetary systems about stars such as Barnard's star. The proposed NASA-Ames Project Cyclops, consisting of a 10 km phased array of 1026 dishes (perhaps on the back side of the moon), as well as a Soviet proposal to assemble 2 similar telescopes at the orbit of Saturn, would search in the radio frequency range for planets 100 light years or more distant.

  12. On finite density effects on cosmic reheating and moduli decay and implications for Dark Matter production

    SciTech Connect

    Drewes, Marco

    2014-11-01

    We study the damping of an oscillating scalar field in a Friedmann-Robertson-Walker spacetime by perturbative processes, taking into account the back-reaction of the plasma of decay products on the damping rate. The scalar field may be identified with the inflaton, in which case this process resembles the reheating of the universe after inflation. It can also model a modulus that dominates the energy density of the universe at later times. We find that the finite density corrections to the damping rate can have a drastic effect on the thermal history and considerably increase both, the maximal temperature in the early universe and the reheating temperature at the onset of the radiation dominated era. As a result the abundance of some Dark Matter candidates may be considerably larger than previously estimated. We give improved analytic estimates for the maximal and the reheating temperatures and confirm them numerically in a simple model.

  13. Simulations of weak gravitational lensing - II. Including finite support effects in cosmic shear covariance matrices

    NASA Astrophysics Data System (ADS)

    Harnois-Déraps, Joachim; van Waerbeke, Ludovic

    2015-07-01

    Numerical N-body simulations play a central role in the assessment of weak gravitational lensing statistics, residual systematics and error analysis. In this paper, we investigate and quantify the impact of finite simulation volume on weak lensing two- and four-point statistics. These finite support (FS) effects are modelled for several estimators, simulation box sizes and source redshifts, and validated against a new large suite of 500 N-body simulations. The comparison reveals that our theoretical model is accurate to better than 5 per cent for the shear correlation function ξ+(θ) and its error. We find that the most important quantities for FS modelling are the ratio between the measured angle θ and the angular size of the simulation box at the source redshift, θbox(zs), or the multipole equivalent ℓ/ℓbox(zs). When this ratio reaches 0.1, independently of the source redshift, the shear correlation function ξ+ is suppressed by 5, 10, 20 and 25 per cent for Lbox = 1000, 500, 250 and 147 h-1 Mpc, respectively. The same effect is observed in ξ-(θ), but at much larger angles. This has important consequences for cosmological analyses using N-body simulations and should not be overlooked. We propose simple semi-analytic correction strategies that account for shape noise and survey masks, generalizable to any weak lensing estimator. From the same simulation suite, we revisit the existing non-Gaussian covariance matrix calibration of the shear correlation function, and propose a new one based on the 9-year Wilkinson Microwave Anisotropy Probe)+baryon acoustic oscillations+supernova cosmology. Our calibration matrix is accurate at 20 per cent down to the arcminute scale, for source redshifts in the range 0 < z < 3, even for the far off-diagonal elements. We propose, for the first time, a parametrization for the full ξ- covariance matrix, also 20 per cent accurate for most elements.

  14. Pulsed Laser System to Simulate Effects of Cosmic Rays in Semiconductor Devices

    NASA Technical Reports Server (NTRS)

    Aveline, David C.; Adell, Philippe C.; Allen, Gregory R.; Guertin, Steven M.; McClure, Steven S.

    2011-01-01

    Spaceflight system electronic devices must survive a wide range of radiation environments with various particle types including energetic protons, electrons, gamma rays, x-rays, and heavy ions. High-energy charged particles such as heavy ions can pass straight through a semiconductor material and interact with a charge-sensitive region, generating a significant amount of charge (electron-hole pairs) along their tracks. These excess charges can damage the device, and the response can range from temporary perturbations to permanent changes in the state or performance. These phenomena are called single event effects (SEE). Before application in flight systems, electronic parts need to be qualified and tested for performance and radiation sensitivity. Typically, their susceptibility to SEE is tested by exposure to an ion beam from a particle accelerator. At such facilities, the device under test (DUT) is irradiated with large beams so there is no fine resolution to investigate particular regions of sensitivity on the parts. While it is the most reliable approach for radiation qualification, these evaluations are time consuming and costly. There is always a need for new cost-efficient strategies to complement accelerator testing: pulsed lasers provide such a solution. Pulsed laser light can be utilized to simulate heavy ion effects with the advantage of being able to localize the sensitive region of an integrated circuit. Generally, a focused laser beam of approximately picosecond pulse duration is used to generate carrier density in the semiconductor device. During irradiation, the laser pulse is absorbed by the electronic medium with a wavelength selected accordingly by the user, and the laser energy can ionize and simulate SEE as would occur in space. With a tightly focused near infrared (NIR) laser beam, the beam waist of about a micrometer can be achieved, and additional scanning techniques are able to yield submicron resolution. This feature allows mapping of all

  15. Maria Montessori's Cosmic Vision, Cosmic Plan, and Cosmic Education

    ERIC Educational Resources Information Center

    Grazzini, Camillo

    2013-01-01

    This classic position of the breadth of Cosmic Education begins with a way of seeing the human's interaction with the world, continues on to the grandeur in scale of time and space of that vision, then brings the interdependency of life where each growing human becomes a participating adult. Mr. Grazzini confronts the laws of human nature in…

  16. Solar Effects on Global Climate Due to Cosmic Rays and Solar Energetic Particles

    NASA Technical Reports Server (NTRS)

    Turco, R. P.; Raeder, J.; DAuria, R.

    2005-01-01

    Although the work reported here does not directly connect solar variability with global climate change, this research establishes a plausible quantitative causative link between observed solar activity and apparently correlated variations in terrestrial climate parameters. Specifically, we have demonstrated that ion-mediated nucleation of atmospheric particles is a likely, and likely widespread, phenomenon that relates solar variability to changes in the microphysical properties of clouds. To investigate this relationship, we have constructed and applied a new model describing the formation and evolution of ionic clusters under a range of atmospheric conditions throughout the lower atmosphere. The activation of large ionic clusters into cloud nuclei is predicted to be favorable in the upper troposphere and mesosphere, and possibly in the lower stratosphere. The model developed under this grant needs to be extended to include additional cluster families, and should be incorporated into microphysical models to further test the cause-and-effect linkages that may ultimately explain key aspects of the connections between solar variability and climate.

  17. Dose Effect of Cosmic Rays in Aircraft at SPE in Fall of 2003

    NASA Astrophysics Data System (ADS)

    Fujitaka, K.; Uchihori, Y.; Kitamura, H.; Nojima, K.; Takada, M.; Yasuda, N.; Okano, M.

    A large solar flare occurred in October 28, 2003, which caused a sensation around the world. Our group decided to measure the aviation dose promptly and started the survey within two days. Measurements have been conducted in Oct.30-Oct.30, Oct.30*-Nov.11*, Oct. 31-Oct.31, Oct.31*-Nov.3*, Nov.3-Nov.3, Nov.5-Nov.5, Nov.5*-Nov.7*, and Nov.6-Nov.6. Here, days with asterisks represent Tokyo to JFK (and vice versa) airport, while others represent Tokyo from/to Sapporo. Unfortunately, the measurement met the flare only once (Nov.3), but the dose was suppressed considerably in the nearby date, and a typical Forbush decrease is seen (Oct.31). While the dose measured in the Tokyo/JFK flight (Oct.31) varied largely, we cannot infer the net dose contribution from the flare. That is because any small variation of the dose tends to be masked by other large one. In short, we do not have to worry about effect of solar activity on board airplane in the present case.

  18. Cosmic Microwave Background Fluctuations from the Kinetic Sunyaev-Zeldovich Effect as a Cosmological Probe

    NASA Astrophysics Data System (ADS)

    Park, Hyunbae; Shapiro, P.; Komatsu, E.

    2012-01-01

    We present a calculation of the kinetic Sunyaev-Zel'dovich (kSZ) effect on of the Comic Microwave Background fluctuation. We focus on the scale at the multipole moment of l = 3000 10000 that is currently being probed by the South Pole Telescope (SPT) and the Atacama Cosmology Telescope. For the post-reionization contribution of the total signal, we use the 3rd order perturbation theory (3PT) to model non-linearity of post-reionization epoch. We evaluate a non-linear expression for momentum powerspectrum in Ma and Fry (2002) with the 3PT density and velocity powerspectrum. And, we use the 3PT momentum powerspectrum to calculate the kSZ signal. We show that the 3PT is a reasonable approximation by comparing our result with previous work by Zhang, Pen and Trac (2004). For reionization contribution, we use our N-body radiative transfer simulations to take patchiness of ionization of intergalactic medium in reionization epoch into account. Using ionized fraction field in the simulation, we calculate the momentum field of the ionized gas. And, we correct for the missing power in finite size boxes of simulations. Finally, we show the kSZ calculation for different simulations with reionization scenarios. With contributions from each epoch, we predict total kSZ signal for different reionization history and put constraint on reionization scenario using an upper bound of the signal from recent SPT measurement.

  19. Delayed recombination and cosmic parameters

    SciTech Connect

    Galli, Silvia; Melchiorri, Alessandro; Bean, Rachel; Silk, Joseph

    2008-09-15

    Current cosmological constraints from cosmic microwave background anisotropies are typically derived assuming a standard recombination scheme, however additional resonance and ionizing radiation sources can delay recombination, altering the cosmic ionization history and the cosmological inferences drawn from the cosmic microwave background data. We show that for recent observations of the cosmic microwave background anisotropy, from the Wilkinson microwave anisotropy probe satellite mission (WMAP) 5-year survey and from the arcminute cosmology bolometer array receiver experiment, additional resonance radiation is nearly degenerate with variations in the spectral index, n{sub s}, and has a marked effect on uncertainties in constraints on the Hubble constant, age of the universe, curvature and the upper bound on the neutrino mass. When a modified recombination scheme is considered, the redshift of recombination is constrained to z{sub *}=1078{+-}11, with uncertainties in the measurement weaker by 1 order of magnitude than those obtained under the assumption of standard recombination while constraints on the shift parameter are shifted by 1{sigma} to R=1.734{+-}0.028. From the WMAP5 data we obtain the following constraints on the resonance and ionization sources parameters: {epsilon}{sub {alpha}}<0.39 and {epsilon}{sub i}<0.058 at 95% c.l.. Although delayed recombination limits the precision of parameter estimation from the WMAP satellite, we demonstrate that this should not be the case for future, smaller angular scales measurements, such as those by the Planck satellite mission.

  20. Cosmic secrets

    NASA Astrophysics Data System (ADS)

    Schommers, W.

    1. The absolute truth. 1.1. Final truth. 1.2. Two important questions. 1.3. Why does the cosmos exist? 1.4. Are the laws of nature independent of the observer's own nature? 1.5. Self0indulgence was dominant. 1.6. Newton's mechanics and its overestimation. 1.7. Scientific realism. 1.8. An important principle: as little outside world as possible. 1.9. Inside world and outside world. 1.10. Principal questions. 1.11. How does science progress? 1.12. Final remarks -- 2. The projection principle. 2.1. The elements of space and time. 2.2. Relationship between matter and space-time. 2.3. Two relevant features. 2.4. Two kinds of "objects". 2.5. Perception processes. 2.6. Inside world and outside world. 2.7. The influence of evolution. 2.8. Information in the picture versus information in basic reality (outside reality). 2.9. Other biological systems. 2.10. How many (geometrical) objects can be in space-time? 2.11. Two types of space-time? 2.12. Summary -- 3. Fictitious realities. 3.1. Conventional quantum theory: critical remarks. 3.2. The projection principle in connection with fictitious realities. 3.3. Distribution of information. 3.4. Basic transformation effects. 3.5. Pictures within projection theory. 3.6. Auxiliary construction. 3.7. Basic laws. 3.8. Extension of conventional quantum theory. 3.9. Only processes are relevant! 3.10. Interactions. 3.11. Distance-independent interactions. 3.12. Arbitrary jumps within (r, t)-space. 3.13.Mach's principle: preliminary remarks. 3.14. Can a lone, elementary object exist in the cosmos? 3.15. The meaning of the potential functions. 3.16. Time. 3.17. Time travel in physics. 3.18. Summary -- 4. Basic reality and levels of reality. 4.1. Hard objects. 4.2. General physical laws. 4.3. States of mind. 4.4. Outside world and basic reality. 4.5. Objective processes. 4.6. Observations. 4.7. No interactions within (r, t)-space. 4.8. The general cannot be deduced from the particular. 4.9. Remarks on the notion "world equation". 4.10. On

  1. Cosmic Rays Variations and Human Physiological State

    NASA Astrophysics Data System (ADS)

    Dimitrova, S.

    2009-12-01

    It was obtained in our previous investigations that geomagnetic activity as an indirect indicator of solar activity correlates with some human physiological and psycho-physiological parameters. A lot of studies indicate that other parameters of space weather like cosmic rays Forbush decreases affect myocardial infarction, brain stroke, car accidents, etc. The purpose of that work was to study the effect of cosmic rays variations on human physiological status. It was established that the decrease in cosmic rays intensity was related to an increase in systolic and diastolic blood pressure and reported subjective psycho-physiological complaints in healthy volunteers.

  2. Cosmic ray isotopes

    NASA Technical Reports Server (NTRS)

    Stone, E. C.

    1973-01-01

    The isotopic composition of cosmic rays is studied in order to develop the relationship between cosmic rays and stellar processes. Cross section and model calculations are reported on isotopes of H, He, Be, Al and Fe. Satellite instrument measuring techniques separate only the isotopes of the lighter elements.

  3. Interactions of cosmic superstrings

    SciTech Connect

    Jackson, Mark G.; /Fermilab

    2007-06-01

    We develop methods by which cosmic superstring interactions can be studied in detail. These include the reconnection probability and emission of radiation such as gravitons or small string loops. Loop corrections to these are discussed, as well as relationships to (p; q)-strings. These tools should allow a phenomenological study of string models in anticipation of upcoming experiments sensitive to cosmic string radiation.

  4. Deepening Cosmic Education

    ERIC Educational Resources Information Center

    Leonard, Gerard

    2013-01-01

    This article is a special blend of research, theory, and practice, with clear insight into the origins of Cosmic Education and cosmic task, while recalling memories of student explorations in botany, in particular, episodes from Mr. Leonard's teaching. Mr. Leonard speaks of a storytelling curriculum that eloquently puts perspective into dimensions…

  5. Unveiling the Origin of Cosmic Rays

    NASA Astrophysics Data System (ADS)

    Olinto, Angela V.

    2015-04-01

    The origin of cosmic rays, relativistic particles that range from below GeVs to hundreds of EeVs, is a century old mystery. Extremely energetic phenomena occurring over a wide range of scales, from the Solar System to distant galaxies, are needed to explain the non-thermal particle spectrum that covers over 12 orders of magnitude. Space Missions are the most effective platforms to study the origin and history of these cosmic particles. Current missions probe particle acceleration and propagation in the Solar System and in our Galaxy. This year ISS-CREAM and CALET join AMS in establishing the International Space Station as the most active site for studying the origin of Galactic cosmic rays. These missions will study astrophysical cosmic ray accelerators as well as other possible sources of energetic particles such as dark matter annihilation or decay. In the future, the ISS may also be the site for studying extremely high-energy extragalactic cosmic rays with JEM-EUSO. We review recent results in the quest for unveiling the sources of energetic particles with balloons and space payloads and report on activities of the Cosmic ray Science Interest Group (CosmicSIG) under the Physics of the Cosmos Program Analysis Group (PhysPAG).

  6. The Cosmic DUNE dust astronomy mission

    NASA Astrophysics Data System (ADS)

    Grun, E.; Srama, R.; Cosmic Dune Team

    A dust astronomy mission aims at the simultaneous measurement of the origin and the chemical composition of individual dust grains in space. Interstellar dust traversing the solar system constitutes the galactic solid phase of matter from which stars and planetary systems form. Interplanetary dust, from comets and asteroids, represents remnant material from bodies at different stages of early solar system evolution. Thus, studies of interstellar and interplanetary dust with Cosmic DUNE (Cosmic Dust Near Earth) will provide a comparison between the composition of the interstellar medium and primitive planetary objects. Cosmic DUNE will prepare the way for effective collection in near-Earth space of interstellar and interplanetary dust for subsequent return to Earth and analysis in laboratories. Cosmic DUNE establishes the next logical step beyond NASA's Stardust mission, with four major advancements in cosmic dust research: (1) Analysis of the elemental and isotopic composition of individual cosmic dust grains, (2) determination of the size distribution of interstellar dust, (3) characterization of the interstellar dust flow through the planetary system, and (4) analysis of interplanetary dust of cometary and asteroidal origin. This mission goal will be reached with novel dust instrumentation. A dust telescope trajectory sensor has been developed which is capable of obtaining precision trajectories of sub-micron sized particles in space. A new high mass resolution dust analyzer of 0.1m2 impact area can cope with the low fluxes expected in interplanetary space. Cosmic DUNE will be proposed to ESA in response to its upcoming call for mission ideas.

  7. Quantitative estimates of the effects of cross section uncertainties on the derivation of GCR source composition. [Galactic Cosmic Rays

    NASA Technical Reports Server (NTRS)

    Hinshaw, G. F.; Wiedenbeck, M. E.

    1983-01-01

    Cosmic-ray source abundance uncertainties, resulting from the cross-section uncertainties, are calculated for the elements carbon through nickel. A significant dominance of cross-section errors in the source abundance uncertainties is found for most of the elements considered, even with uncorrelated partial cross-section errors; much larger uncertainties than those reported previously are found for Ca, N, Na, Al, and S. Propagation errors are noted to preclude a significant determination of source abundances for F, Cl, and Mn. A need for an assessment of the existing cosmic-ray propagation models - especially the propagation cross-sections which they employ - is expressed, motivated by recent improvements in the resolution and statistical accuracy of observations.

  8. Effects of Cosmic Infrared Background on High Energy Delayed Gamma-Rays From Gamma-Ray Bursts

    SciTech Connect

    Murase, Kohta; Asano, Katsuaki; Nagataki, Shigehiro; /Kyoto U., Yukawa Inst., Kyoto /KIPAC, Menlo Park

    2007-04-06

    Regenerated high energy emissions from gamma-ray bursts (GRBs) are studied in detail. If the primary emission spectrum extends to TeV range, these very high energy photons will be absorbed by the cosmic infrared background (CIB). The created high energy electron-positron pairs up-scatter not only cosmic microwave background (CMB) photons but also CIB photons, and secondary photons are generated in the GeV-TeV range. These secondary delayed photons may be observed in the near future, and useful for a consistency check for the primary spectra and GRB physical parameters. The up-scattered CIB photons cannot be neglected for low redshift bursts and/or GRBs with a relatively low maximum photon energy. The secondary gamma-rays also give us additional information on the CIB, which is uncertain in observations so far.

  9. The effects of cosmic particle radiation on pocket mice aboard Apollo XVII: XI. Results of eye examination.

    PubMed

    Philpott, D E; Corbett, R L; Takahashi, A; Benton, E V; Cruty, M R

    1975-04-01

    Five pocket mice (Perognathus longimembris) were flown on Apollo XVII, and four survived. All the eyes, except one eye from the dead flight mouse, were examined histologically. In the four surviving mice, a total of five cosmic ray particles which had registered in the subscalp particle detectors had trajectories that intersected the eyes. Four of them (Z equal to 6-9 for three of the particles and Z larger than or equal to 10 for the fourth) most likely went through the head before reaching the particle detector, while the thindown direction of the fifth (Z larger than or equal to 10) was not determinable. The retinas of the flight animals were found free from histological alterations such as might have been expected from encounters with cosmic ray particles.

  10. Cosmic Rays and Clouds, 2. Atmospheric Electric Field Effect In Different Neutron Multiplicities According To Emilio Segre' Observatory One Minute Data

    NASA Astrophysics Data System (ADS)

    Dorman, L. I.; Dorman, I. V.; Iucci, N.; Ne'Eman, Yu.; Pustil'Nik, L. A.; Sternlieb, A.; Villoresi, G.; Zukerman, I. G.

    On the basis of cosmic ray and atmospheric electric field one minute data obtained by NM and EFS of Emilio Segre' Observatory (hight 2025 m above s.l., cut-off rigidity for vertical direction 10.8 GV) we determine the atmospheric electric field effect in CR for total neutron intensity and for multiplicities m=1, m=2, m=3, m=4, m=5, m=6, and m=7. For comparison and excluding primary CR variations we use also one minute data on neutron multiplicities obtained by NM of University "Roma Tre" (about sea level, cut-off rigidity 6.7 GV). In February 2000 were observed 14 periods of thun- derstorms with different durations (up to about 1000 min), the maximum strength of electric field was 110 kV/m. Thunderstorms were observed also in March 2000 (6 pe- riods with maximal field 112 kV/m), in April 2000 (9; 70 kV/m), in May 2000 (4; 10 kV/m), in October 2000 (10; 70 kV/m), in November 2000 (5; 50 kV/m), in De- cember 2000 (7; 88 kV/m), in January 2001 (12; 62 kV/m), in February 2001 (10; 88 kV/m). According to the theoretical calculations of Dorman and Dorman (1995) the electric field effect in the NM counting rate must be caused mainly by captchuring of slow negative muons by lead nucleus with escaping few neutrons. As it was shown in Dorman et al. (1999), the biggest electric field effect is expected in the multiplicity m=1, much smaller in m=2 and negligible effect is expected in higher multiplicities. We will control this conclusion on the basis of our experimental data. Obtained results give a possibility to estimate total acceleration and deceleration of CR particles by the atmospheric electric field. REFERENCES: Dorman L.I. and Dorman I.V., 1995. "Cosmic-ray atmospheric electric field effects". Canadian J. of Physics, Vol. 73, pp. 440-443. L.I. Dorman, I.V. Dorman, N. Iucci, M. Parisi, G. Villoresi, and I.G. Zuk- erman, 1999. "Emilio Segre' Observatory and Expected Time-Variations of Neutron Monitor Total and Multiplicities Counting Rates Caused by Cosmic Ray Particle

  11. Domain wall contribution to the nonlinear dielectric response: effective potential model

    NASA Astrophysics Data System (ADS)

    Placeres-Jiménez, R.; Rino, J. P.; Gonçalves, A. M.; Eiras, J. A.

    2015-11-01

    Domain wall displacement has an important contribution to the different nonlinear dielectric responses observed in ferroelectrics. For a moderated alternating electric field, domain walls perform a small displacement around their equilibrium positions. Such motion of the domain walls can be modelled as a body moving in a viscous medium under the action of an effective potential W(l). From this model the dispersion relationships are derived. The exact expression for the effective potential is found assuming that the dielectric permittivity depends on the electric field strength as \\varepsilon \\propto 1/(α +β {{E}2}) . The effect of multidomain structure and polarization hysteresis are introduced through the effective field approximation {{E}\\text{eff}}\\equiv E+κ P(E) . An important merit of the model is that it allows the simulation of transient polarization processes for the arbitrary input signal, predicting a power law for the polarization and depolarization currents. An analytic expression is found for the dependence of the permittivity on the electric field strength that correctly reproduces its hysteretic behaviour. The polarization loop and nonlinear dielectric response for subswitching the alternating electric field are simulated and compared with experimental data obtained from PZT thin films. It was observed that the simulated dielectric loss was lower than the experimental one, which can be explained as a result of the interaction of domain walls with defects. Point defects are introduced into the model as a perturbation of the effective potential, showing the dependence of the dielectric loss on the concentration of the defects.

  12. Our Cosmic Insignificance

    PubMed Central

    Kahane, Guy

    2014-01-01

    The universe that surrounds us is vast, and we are so very small. When we reflect on the vastness of the universe, our humdrum cosmic location, and the inevitable future demise of humanity, our lives can seem utterly insignificant. Many philosophers assume that such worries about our significance reflect a banal metaethical confusion. They dismiss the very idea of cosmic significance. This, I argue, is a mistake. Worries about cosmic insignificance do not express metaethical worries about objectivity or nihilism, and we can make good sense of the idea of cosmic significance and its absence. It is also possible to explain why the vastness of the universe can make us feel insignificant. This impression does turn out to be mistaken, but not for the reasons typically assumed. In fact, we might be of immense cosmic significance—though we cannot, at this point, tell whether this is the case. PMID:25729095

  13. Alpha-amylase starch binding domains: cooperative effects of binding to starch granules of multiple tandemly arranged domains.

    PubMed

    Guillén, D; Santiago, M; Linares, L; Pérez, R; Morlon, J; Ruiz, B; Sánchez, S; Rodríguez-Sanoja, R

    2007-06-01

    The Lactobacillus amylovorus alpha-amylase starch binding domain (SBD) is a functional domain responsible for binding to insoluble starch. Structurally, this domain is dissimilar from other reported SBDs because it is composed of five identical tandem modules of 91 amino acids each. To understand adsorption phenomena specific to this SBD, the importance of their modular arrangement in relationship to binding ability was investigated. Peptides corresponding to one, two, three, four, or five modules were expressed as His-tagged proteins. Protein binding assays showed an increased capacity of adsorption as a function of the number of modules, suggesting that each unit of the SBD may act in an additive or synergic way to optimize binding to raw starch.

  14. Direct Observation of Cosmic Strings Via Their Strong Gravitational Lensing Effect. 1. Predictions for High Resolution Imaging Surveys

    SciTech Connect

    Gasparini, Maria Alice; Marshall, Phil; Treu, Tommaso; Morganson, Eric; Dubath, Florian; /Santa Barbara, KITP

    2007-11-14

    We use current theoretical estimates for the density of long cosmic strings to predict the number of strong gravitational lensing events in astronomical imaging surveys as a function of angular resolution and survey area. We show that angular resolution is the single most important factor, and that interesting limits on the dimensionless string tension G{mu}/c{sup 2} can be obtained by existing and planned surveys. At the resolution of the Hubble Space Telescope (0'.14), it is sufficient to survey of order a square degree -- well within reach of the current HST archive -- to probe the regime G{mu}/c{sup 2} {approx} 10{sup -8}. If lensing by cosmic strings is not detected, such a survey would improve the limit on the string tension by an order of magnitude on that available from the cosmic microwave background. At the resolution (0'.028) attainable with the next generation of large ground based instruments, both in the radio and the infra-red with adaptive optics, surveying a sky area of order ten square degrees will allow us to probe the G{mu}/c{sup 2} {approx} 10{sup -9} regime. These limits will not be improved significantly by increasing the solid angle of the survey.

  15. The effect of the changing polarity and neutral sheet of the IMF on the cosmic ray diurnal anisotropy at neutron monitor energies

    NASA Technical Reports Server (NTRS)

    Van Staden, M. L.; Potgieter, M. S.

    1991-01-01

    A drift with a simulated wavy neutral sheet have been used to study the effects of the reversal of the solar magnetic field every 11 years and the changes in the waviness of the heliospheric neutral sheet, corresponding to changes in solar activity, on the diurnal anisotropy at an energy of 20 GeV. The results indicate that the long-term behavior of the diurnal anisotropy, especially the phase shift from one solar minimum period to another, which seems to depend on the polarity of the IMF, has a theoretical explanation in the drift picture of the modulation of cosmic rays in the heliosphere.

  16. Cosmic Microwave Background Data Analysis

    NASA Astrophysics Data System (ADS)

    Paykari, Paniez; Starck, Jean-Luc Starck

    2012-03-01

    gravitational lensing of the CMB and the integrated Sachs Wolfe (ISW) effect [82]; (4) observing bright extragalactic radio and infrared sources; (5) observing the local interstellar medium, distributed synchrotron emission, and the galactic magnetic field; (6) studying the local Solar System (planets, asteroids, comets, and the zodiacal light). Planck is expected to yield data on a number of astronomical issues by 2012. It is thought that Planck measurements will mostly be limited by the efficiency of foreground removal, rather than the detector performance or duration of the mission - this is particularly important for the polarization measurements. Technological developments over the last two decades have accelerated the progress in observational cosmology. The interplay between the new theoretical ideas and new observational data has taken cosmology from a purely theoretical domain into a field of rigorous experimental science andwe are nowin what is called the precision cosmology era. The CMB measurements have made the inflationary Big Bang theory the standard model of the early Universe. This theory predicts a roughly Gaussian distribution for the initial conditions of the Universe. The power spectrum of these fluctuations agrees well with the observations, although certain observables, such as the overall amplitude of the fluctuations, remain as free parameters of the cosmic inflation model.

  17. Single Molecule Effects of Osteogenesis Imperfecta Mutations in Tropocollagen Protein Domains

    DTIC Science & Technology

    2008-12-02

    associated symptoms, including short stature, loose joints, blue sclearae, dentinogenesis imperfecta , hearing loss , and neurological and pulmo- nary...Single molecule effects of osteogenesis imperfecta mutations in tropocollagen protein domains Alfonso Gautieri,1,2 Simone Vesentini,2 Alberto...2008 proteinscience.org Abstract: Osteogenesis imperfecta (OI) is a genetic disease characterized by fragile bones, skeletal deformities and, in severe

  18. The Dynamics of Effective Performance Evaluation Systems in Education: Conceptual, Human Relations, and Technical Domains.

    ERIC Educational Resources Information Center

    Stronge, James H.

    1991-01-01

    A triad of conceptual, human relations, and technical domains is proposed as a basis for effective performance evaluation systems in education. Systems incorporating the relevant issues in this triad address a fundamental rule of performance evaluation: if it is worth doing, it is worth doing well. (SLD)

  19. When Should I Trust My Gut? Linking Domain Expertise to Intuitive Decision-Making Effectiveness

    ERIC Educational Resources Information Center

    Dane, Erik; Rockmann, Kevin W.; Pratt, Michael G.

    2012-01-01

    Despite a growing body of scholarship on the concept of intuition, there is a scarcity of empirical research spotlighting the circumstances in which intuitive decision making is effective relative to analytical decision making. Seeking to address this deficiency, we conducted two laboratory studies assessing the link between domain expertise (low…

  20. The Effect of School Counselors' Domain Specialization on Seniors' Milestone Completion and College Access Planning

    ERIC Educational Resources Information Center

    Bond, Nancy J.

    2013-01-01

    The purpose of this study was to determine the effect of senior high school counselors' domain specializations--academic, advanced education, career, and personal/social--from two urban high schools, on alphabetically assigned graduating seniors' with low, mid-range, and high Grade Point Averages documented college and career readiness milestone…

  1. Differential Effects of Language Attrition in the Domains of Verb Placement and Object Expression

    ERIC Educational Resources Information Center

    Flores, Cristina

    2012-01-01

    This study investigates the differential effects of language attrition in two diverse linguistic domains: verb placement and object expression. Linguistic phenomena at the syntax--discourse interface, such as object expression, have been shown to be more vulnerable to attrition than narrow syntax properties, such as verb placement. This study aims…

  2. Effect of Teachers' Stereotyping on Students' Stereotyping of Mathematics as a Male Domain.

    ERIC Educational Resources Information Center

    Keller, Carmen

    2001-01-01

    Examines the effects of teachers' stereotypes towards mathematics, based upon the beliefs of their students in grades six to eight in Switzerland. Reports that mathematics was stereotyped as a male domain by teachers and students; while teachers' beliefs affected their students after controlling for achievement, interest, and self-confidence in…

  3. Temperature dependence of the spin torque effect in current-induced domain wall motion.

    PubMed

    Laufenberg, M; Bührer, W; Bedau, D; Melchy, P-E; Kläui, M; Vila, L; Faini, G; Vaz, C A F; Bland, J A C; Rüdiger, U

    2006-07-28

    We present an experimental study of domain wall motion induced by current pulses as well as by conventional magnetic fields at temperatures between 2 and 300 K in a 110 nm wide and 34 nm thick Ni80Fe20 ring. We observe that, in contrast with field-induced domain wall motion, which is a thermally activated process, the critical current density for current-induced domain wall motion increases with increasing temperature, which implies a reduction of the spin torque efficiency. The effect of Joule heating due to the current pulses is measured and taken into account to obtain critical fields and current densities at constant sample temperatures. This allows for a comparison of our results with theory.

  4. Domain identification moderates the effect of positive stereotypes on Chinese American women's math performance.

    PubMed

    Saad, Carmel S; Meyer, Oanh L; Dhindsa, Manveen; Zane, Nolan

    2015-01-01

    We examined whether an individual difference factor, math domain identification, moderated performance following positive stereotype activation. We hypothesized that positive stereotype activation would improve performance for those more math identified (compared to a control condition), but would hinder performance for those less math identified. We examined 116 Chinese American women (mean age = 19 years). Participants were assigned to the positive stereotype activation condition or to the control condition before completing a math test. Positive stereotype activation led more math identified participants to perform significantly better than the control condition, whereas it led less math identified participants to perform significantly worse than the control condition. Domain identification moderates the effect of positive stereotype activation. Educators should consider how testing situations are constructed, especially when test takers do not identify highly with the domain.

  5. The Effect of Top-Level Domains and Advertisements on Health Web Site Credibility

    PubMed Central

    Wang, Zuoming; Loh, Tracy

    2004-01-01

    Background Concerns over health information on the Internet have generated efforts to enhance credibility markers; yet how users actually assess the credibility of online health information is largely unknown. Objective This study set out to (1) establish a parsimonious and valid questionnaire instrument to measure credibility of Internet health information by drawing on various previous measures of source, news, and other credibility scales; and (2) to identify the effects of Web-site domains and advertising on credibility perceptions. Methods Respondents (N = 156) examined one of 12 Web-site mock-ups and completed credibility scales in a 3 x 2 x 2 between-subjects experimental design. Factor analysis and validity checks were used for item reduction, and analysis of variance was employed for hypothesis testing of Web-site features' effects. Results In an attempt to construct a credibility instrument, three dimensions of credibility (safety, trustworthiness, and dynamism) were retained, reflecting traditional credibility sub-themes, but composed of items from disparate sources. When testing the effect of the presence or absence of advertising on a Web site on credibility, we found that this depends on the site's domain, with a trend for advertisements having deleterious effects on the credibility of sites with .org domain, but positive effects on sites with .com or .edu domains. Conclusions Health-information Web-site providers should select domains purposefully when they can, especially if they must accept on-site advertising. Credibility perceptions may not be invariant or stable, but rather are sensitive to topic and context. Future research may employ these findings in order to compare other forms of health-information delivery to optimal Web-site features. PMID:15471750

  6. Research in cosmic and gamma ray astrophysics: Cosmic physics portion

    NASA Technical Reports Server (NTRS)

    Stone, Edward C.; Mewaldt, Richard A.; Schindler, Stephen

    1993-01-01

    Research in particle astrophysics at the Space Radiation Laboratory (SRL) of the California Institute of Technology is supported under NASA Grant NAGW-1919. A three-year proposal for continuation of support was submitted a year ago and put into effect 1 October 1992. This report is the combined progress report and continuation application called for under the Federal Demonstration Project. Gamma-ray Astrophysics at SRL is separately supported under NAGW-1919 and will be separately summarized and proposed. This report will document progress and plans for our particle spectroscopy activities and for related data analysis, calibration, and community service activities. A bibliography and a budget will be attached as appendices. The Caltech SRL research program includes a heavy emphasis on elemental and isotopic spectroscopy of energetic particles in the cosmic radiation; in solar, interplanetary, and anomalous 'cosmic' radiation; and in planetary magnetospheres as discussed.

  7. Passive microrheology in the effective time domain: analyzing time dependent colloidal dispersions.

    PubMed

    Vyas, Bhavna M; Orpe, Ashish V; Kaushal, Manish; Joshi, Yogesh M

    2016-10-21

    We studied the aging dynamics of an aqueous suspension of LAPONITE®, a model time dependent soft glassy material, using a passive microrheology technique. This system is known to undergo physical aging during which its microstructure evolves progressively to explore lower free energy states. Optical microscopy is used to monitor the motion of micron-sized tracer probes embedded in a sample kept between two glass plates. The mean square displacements (MSD) obtained from the motion of the tracer particles show a systematic change from a purely diffusive behavior at short aging times to a subdiffusive behavior as the material ages. Interestingly, the MSDs at all the aging times as well as different LAPONITE® concentrations superpose remarkably to show a time-aging time master curve when the system is transformed from the real time domain to the effective time domain, which is obtained by rescaling the material clock to account for the age dependent relaxation time. The transformation of the master curve from the effective time domain to the real time domain leads to the prediction of the MSD in real time over a span of 5 decades when the measured data at individual aging times are only over 2 decades. Since the MSD obtained from microrheology is proportional to the creep compliance of a material, by using the Boltzmann superposition principle along with the convolution relation in the effective time domain, we predict the stress relaxation behavior of the system in real time. This work shows that the effective time approach applied to microrheology facilitates the prediction of long time creep and relaxation dynamics of a time dependent soft material by carrying out short time experiments at different aging times.

  8. Scaling of domain size during spinodal decomposition : dislocation discreteness and mobility effects.

    SciTech Connect

    Provatas, Nikolas; Leonard, Francois Leonard; Mahon, Jennifer; Haataja, Mikko

    2005-06-01

    In this letter, we examine the effects of discrete mobile dislocations on spinodal decomposition kinetics in lattice mismatched binary alloys. By employing a novel continuum model, we demonstrate that the effects of dislocation mobility on domain coarsening kinetics can be expressed in a unified manner through a scaling function, describing a crossover from t{sup 1/2} to t{sup 1/3} behavior.

  9. Development of the cosmic ray techniques

    NASA Technical Reports Server (NTRS)

    Rossi, B.

    1982-01-01

    It has been found that most advances of cosmic-ray physics have been directly related to the development of observational techniques. The history of observational techniques is discussed, taking into account ionization chambers, refinements applied to ionization chambers to make them suitable for an effective use in the study of cosmic radiation, the Wulf-type electrometer, the electrometer designed by Millikan and Neher, the Geiger-Mueller counter, the experiment of Bothe and Kolhoerster, the coincidence circuit, and a cosmic-ray 'telescope'. Attention is given to a magnetic lens for cosmic rays, a triangular arrangement of Geiger-Mueller counters used to demonstrate the production of a secondary radiation, a stereoscopic cloud-chamber photograph of showers, the cloud-chamber picture which provided the first evidence of the positive electron, and arrangements for studying photon components, mu-mesons, and air showers.

  10. Development of the cosmic ray techniques

    NASA Astrophysics Data System (ADS)

    Rossi, B.

    1982-12-01

    It has been found that most advances of cosmic-ray physics have been directly related to the development of observational techniques. The history of observational techniques is discussed, taking into account ionization chambers, refinements applied to ionization chambers to make them suitable for an effective use in the study of cosmic radiation, the Wulf-type electrometer, the electrometer designed by Millikan and Neher, the Geiger-Mueller counter, the experiment of Bothe and Kolhoerster, the coincidence circuit, and a cosmic-ray 'telescope'. Attention is given to a magnetic lens for cosmic rays, a triangular arrangement of Geiger-Mueller counters used to demonstrate the production of a secondary radiation, a stereoscopic cloud-chamber photograph of showers, the cloud-chamber picture which provided the first evidence of the positive electron, and arrangements for studying photon components, mu-mesons, and air showers.

  11. Supermassive cosmic string compactifications

    SciTech Connect

    Blanco-Pillado, Jose J.; Reina, Borja; Sousa, Kepa; Urrestilla, Jon E-mail: borja.reina@ehu.es E-mail: jon.urrestilla@ehu.es

    2014-06-01

    The space-time dimensions transverse to a static straight cosmic string with a sufficiently large tension (supermassive cosmic strings) are compact and typically have a singularity at a finite distance form the core. In this paper, we discuss how the presence of multiple supermassive cosmic strings in the 4d Abelian-Higgs model can induce the spontaneous compactification of the transverse space and explicitly construct solutions where the gravitational background becomes regular everywhere. We discuss the embedding of this model in N = 1 supergravity and show that some of these solutions are half-BPS, in the sense that they leave unbroken half of the supersymmetries of the model.

  12. Cosmic-ray astrochemistry.

    PubMed

    Indriolo, Nick; McCall, Benjamin J

    2013-10-07

    Gas-phase chemistry in the interstellar medium is driven by fast ion-molecule reactions. This, of course, demands a mechanism for ionization, and cosmic rays are the ideal candidate as they can operate throughout the majority of both diffuse and dense interstellar clouds. Aside from driving interstellar chemistry via ionization, cosmic rays also interact with the interstellar medium in ways that heat the ambient gas, produce gamma rays, and produce light element isotopes. In this paper we review the observables generated by cosmic-ray interactions with the interstellar medium, focusing primarily on the relevance to astrochemistry.

  13. Effect of the structure of lipids favoring disordered domain formation on the stability of cholesterol-containing ordered domains (lipid rafts): identification of multiple raft-stabilization mechanisms.

    PubMed

    Bakht, Omar; Pathak, Priyadarshini; London, Erwin

    2007-12-15

    Despite the importance of lipid rafts, commonly defined as liquid-ordered domains rich in cholesterol and in lipids with high gel-to-fluid melting temperatures (T(m)), the rules for raft formation in membranes are not completely understood. Here, a fluorescence-quenching strategy was used to define how lipids with low T(m), which tend to form disordered fluid domains at physiological temperatures, can stabilize ordered domain formation by cholesterol and high-T(m) lipids (either sphingomyelin or dipalmitoylphosphatidylcholine). In bilayers containing mixtures of low-T(m) phosphatidylcholines, cholesterol, and high-T(m) lipid, the thermal stability of ordered domains decreased with the acyl-chain structure of low-T(m) lipids in the following order: diarachadonyl > diphytanoyl > 1-palmitoyl 2-docosahexenoyl = 1,2 dioleoyl = dimyristoleoyl = 1-palmitoyl, 2-oleoyl (PO). This shows that low-T(m) lipids with two acyl chains having very poor tight-packing propensities can stabilize ordered domain formation by high-T(m) lipids and cholesterol. The effect of headgroup structure was also studied. We found that even in the absence of high-T(m) lipids, mixtures of cholesterol with PO phosphatidylethanolamine (POPE) and PO phosphatidylserine (POPS) or with brain PE and brain PS showed a (borderline) tendency to form ordered domains. Because these lipids are abundant in the inner (cytofacial) leaflet of mammalian membranes, this raises the possibility that PE and PS could participate in inner-leaflet raft formation or stabilization. In bilayers containing ternary mixtures of PO lipids, cholesterol, and high-T(m) lipids, the thermal stability of ordered domains decreased with the polar headgroup structure of PO lipids in the order PE > PS > phosphatidylcholine (PC). Analogous experiments using diphytanoyl acyl chain lipids in place of PO acyl chain lipids showed that the stabilization of ordered lipid domains by acyl chain and headgroup structure was not additive. This implies

  14. The effects of exposure to violence and victimization across life domains on adolescent substance use.

    PubMed

    Wright, Emily M; Fagan, Abigail A; Pinchevsky, Gillian M

    2013-11-01

    This study uses longitudinal data from the Project on Human Development in Chicago Neighborhoods (PHDCN) to examine the effects of exposure to school violence, community violence, child abuse, and parental intimate partner violence (IPV) on youths' subsequent alcohol and marijuana use. We also examine the cumulative effects of being exposed to violence across these domains. Longitudinal data were obtained from 1,655 adolescents and their primary caregivers participating in the PHDCN. The effects of adolescents' exposure to various forms of violence across different life domains were examined relative to adolescents' frequency of alcohol and marijuana use three years later. Multivariate statistical models were employed to control for a range of child, parent, and family risk factors. Exposure to violence in a one-year period increased the frequency of substance use three years later, though the specific relationships between victimization and use varied for alcohol and marijuana use. Community violence and child abuse, but not school violence or exposure to IPV, were predictive of future marijuana use. None of the independent measures of exposure to violence significantly predicted future alcohol use. Finally, the accumulation of exposure to violence across life domains was detrimental to both future alcohol and marijuana use. The findings support prior research indicating that exposure to multiple forms of violence, across multiple domains of life, negatively impacts adolescent outcomes, including substance use. The findings also suggest that the context in which exposure to violence occurs should be considered in future research, since the more domains in which youth are exposed to violence, the fewer "safe havens" they have available. Finally, a better understanding of the types of violence youth encounter and the contexts in which these experiences occur can help inform intervention efforts aimed at reducing victimization and its negative consequences.

  15. The effects of cosmic particle radiation on pocket mice aboard Apollo XVIII: VII: results of scalp examination.

    PubMed

    Vogel, F S; Lloyd, B; Cruty, M R; Benton, E V

    1975-04-01

    The scalps of the four pocket mice that were recovered alive from the Apollo XVII flight contained acute focal lesions in the epidermis and an inflammatory reaction in the subjacent dermis and subcutaneous tissue. Hair follicles were focally damaged in three of the four mice. There were 13 scalp lesions singled out in the four flight mice because of histological features that distinguished them from changes observed in the scalps of the control mice. There was only one possible coincidence between a lesion and the trajectory of a cosmic ray particle registered in a subscalp dosimeter. There is, however, a possibility that at least some lesions were produced by unregistered particles.

  16. Cosmic physics data analysis program

    NASA Technical Reports Server (NTRS)

    Wilkes, R. Jeffrey

    1993-01-01

    A data analysis program was carried out to investigate the intensity, propagation, and origin of primary Cosmic Ray Galactic electrons. Scanning was carried out on two new balloon flight experiments as well as the border area of previous experiments. The identification and evaluation of the energies of the primary electrons were carried out. A new analysis of these data were incorporated into an overall evaluation of the roll of electrons in the problem of the origin of cosmic rays. Recent measurements indicate that the earth may be within the expanding Geminga supernova shock wave which is expected to have a major effect upon the propagation and the energy spectrum of galactic electrons. Calculations with the Geminga model indicate that the cut-off energy may be very close to the observed highest energy electrons in our analysis.

  17. Cosmic x ray physics

    NASA Technical Reports Server (NTRS)

    Mccammon, Dan; Cox, D. P.; Kraushaar, W. L.; Sanders, W. T.

    1990-01-01

    The annual progress report on Cosmic X Ray Physics is presented. Topics studied include: the soft x ray background, proportional counter and filter calibrations, the new sounding rocket payload: X Ray Calorimeter, and theoretical studies.

  18. Cosmic x ray physics

    NASA Technical Reports Server (NTRS)

    Mccammon, Dan; Cox, D. P.; Kraushaar, W. L.; Sanders, W. T.

    1991-01-01

    The annual progress report on Cosmic X Ray Physics for the period 1 Jan. to 31 Dec. 1990 is presented. Topics studied include: soft x ray background, new sounding rocket payload: x ray calorimeter, and theoretical studies.

  19. Astrophysics: Cosmic jet engines

    NASA Astrophysics Data System (ADS)

    Young, Andy

    2010-02-01

    In some galaxies, matter falling onto a supermassive black hole is ejected in narrow jets moving at close to the speed of light. New observations provide insight into the workings of these cosmic accelerators.

  20. Cosmic Ray Astronomy

    NASA Technical Reports Server (NTRS)

    Wu, S. T.

    2000-01-01

    The cosmic ray division participation in the cooperative agreement was activated in the second year. The scientific goals will be analysis of cosmic ray data from the Japanese-American Cooperative Emulsion Experiments (JACEE). Measurements of primary cosmic rays in the JACEE emulsion chambers will be made to derive for each detected particle the deposited energy in the chamber and the primary charge (atomic number). The data will be corrected to the primary flux above the atmosphere, and the composition and energy spectra will be derived. The spectra of the individual elements will be interpreted in context with the supernova shock and other models of cosmic ray acceleration. Additional information is contained in the original extended abstract.

  1. 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 January 1994. Tables showing the current inventory of programs available from COSMIC are presented and program processing and evaluation activities are discussed. Marketing and customer service activities in this period are presented as is the progress report of NASTRAN maintenance and support. Tables of disseminations and budget summary conclude the report.

  2. The Cosmic Labyrinth

    NASA Astrophysics Data System (ADS)

    Atkinson, M.

    2011-06-01

    This paper discusses the intertwined relationship between the terrestrial and celestial using the labyrinth as a metaphor referencing sources from art, gardens and Australian Indigenous culture. Including the Morning Star with the labyrinthine mortuary ritual in Arnhem Land, the cosmic plan garden at Auschwitz and Marea Atkinson's art project undertaken at the Villa Garzoni garden in Italy to create The Cosmic Labyrinth installation exhibited at Palazzo Franchetti, Venice, during the sixth conference on the Inspiration of Astronomical Phenomena.

  3. Memory and comprehension for health information among older adults: distinguishing the effects of domain-general and domain-specific knowledge.

    PubMed

    Chin, Jessie; Payne, Brennan; Gao, Xuefei; Conner-Garcia, Thembi; Graumlich, James F; Murray, Michael D; Morrow, Daniel G; Stine-Morrow, Elizabeth A L

    2015-01-01

    While there is evidence that knowledge influences understanding of health information, less is known about the processing mechanisms underlying this effect and its impact on memory. We used the moving window paradigm to examine how older adults varying in domain-general crystallised ability (verbal ability) and health knowledge allocate attention to understand health and domain-general texts. Participants (n = 107, age: 60-88 years) read and recalled single sentences about hypertension and about non-health topics. Mixed-effects modelling of word-by-word reading times suggested that domain-general crystallised ability increased conceptual integration regardless of text domain, while health knowledge selectively increased resource allocation to conceptual integration at clause boundaries in health texts. These patterns of attentional allocation were related to subsequent recall performance. Although older adults with lower levels of crystallised ability were less likely to engage in integrative processing, when they did, this strategy had a compensatory effect in improving recall. These findings suggest that semantic integration during reading is an important comprehension process that supports the construction of the memory representation and is engendered by knowledge. Implications of the findings for theories of text processing and memory as well as for designing patient education materials are discussed.

  4. Effect of methionine80 heme coordination on domain swapping of cytochrome c.

    PubMed

    Hirota, Shun; Yamashiro, Nobuhiro; Wang, Zhonghua; Nagao, Satoshi

    2017-02-28

    Cytochrome c (cyt c) forms oligomers by domain swapping. It exchanges the C-terminal α-helical region between protomers, and the Met80‒heme iron bond is perturbed significantly in domain-swapped oligomers. The peroxidase activity of cyt c increases by Met80 dissociation from the heme iron, which may trigger apoptosis. This study elucidates the effect of the Met80 heme coordination on cyt c domain swapping by obtaining oligomers for both wild-type (WT) and M80A human cyt c by an addition of ethanol to their monomers, followed by lyophilization and dissolution to buffer, and investigating their dimer properties. The absorption and circular dichroism spectra of WT and M80A cyt c exhibited similar changes upon dimerization, indicating that Met80 does not affect the oligomerization process significantly. According to differential scanning calorimetric measurements, Met80 coordination to the heme iron had an effect on the stabilization of the monomer (ΔH = 16 kcal/mol), whereas no large difference was observed between the dimer-to-monomer dissociation temperatures of WT and M80A cyt c (61.0 °C). The activation enthalpy values were similar and relatively large for the dissociation of both WT and M80A cyt c dimers (WT, 120 ± 10 kcal/mol; M80A, 110 ± 10 kcal/mol), indicating that the dimers suffered large structural changes upon dissociation to monomers independent of the Met80 coordination to the heme iron. These results indicate that cyt c domain swapping may occur regardless of the Met80 coordination, whereas the monomer is stabilized by Met80 but the domain-swapped dimer structure and stability are less affected by the Met80 coordination.

  5. Effect of near-earth thunderstorms electric field on the intensity of ground cosmic ray positrons/electrons in Tibet

    NASA Astrophysics Data System (ADS)

    Zhou, X. X.; Wang, X. J.; Huang, D. H.; Jia, H. Y.

    2016-11-01

    Monte Carlo simulations are performed to study the correlation between the ground cosmic ray intensity and near-earth thunderstorms electric field at YBJ (located at YangBaJing, Tibet, China, 4300 m a. s. l.). The variations of the secondary cosmic ray intensity are found to be highly dependent on the strength and polarity of the electric field. In negative fields and in positive fields greater than 600 V/cm, the total number of ground comic ray positrons and electrons increases with increasing electric field strength. And these values increase more obviously when involving a shower with lower primary energy or a higher zenith angle. While in positive fields ranging from 0 to 600 V/cm, the total number of ground comic ray positrons and electrons declines and the amplitude is up to 3.1% for vertical showers. A decrease of intensity occurs in inclined showers within the range of 0-500 V/cm, which is accompanied by smaller amplitudes. In this paper, the intensity changes are analyzed, especially concerning those decreasing phenomena in positive electric fields. Our simulation results could be helpful in understanding the decreases observed in some ground-based experiments (such as the Carpet air shower array and ARGO-YBJ), and also be useful in understanding the acceleration mechanisms of secondary charged particles caused by an atmospheric electric field.

  6. Comparison of CREME (cosmic-ray effects on microelectronics) model LET (linear energy transfer) spaceflight dosimetry data

    SciTech Connect

    Letaw, J.R.; Adams, J.H.

    1986-07-15

    The galactic cosmic radiation (GCR) component of space radiation is the dominant cause of single-event phenomena in microelectronic circuits when Earth's magnetic shielding is low. Spaceflights outside the magnetosphere and in high inclination orbits are examples of such circumstances. In high-inclination orbits, low-energy (high LET) particles are transmitted through the field only at extreme latitudes, but can dominate the orbit-averaged dose. GCR is an important part of the radiation dose to astronauts under the same conditions. As a test of the CREME environmental model and particle transport codes used to estimate single event upsets, we have compiled existing measurements of HZE doses were compiled where GCR is expected to be important: Apollo 16 and 17, Skylab, Apollo Soyuz Test Project, and Kosmos 782. The LET spectra, due to direct ionization from GCR, for each of these missions has been estimated. The resulting comparisons with data validate the CREME model predictions of high-LET galactic cosmic-ray fluxes to within a factor of two. Some systematic differences between the model and data are identified.

  7. Strong Cosmic Censorship

    NASA Astrophysics Data System (ADS)

    Isenberg, James

    2017-01-01

    The Hawking-Penrose theorems tell us that solutions of Einstein's equations are generally singular, in the sense of the incompleteness of causal geodesics (the paths of physical observers). These singularities might be marked by the blowup of curvature and therefore crushing tidal forces, or by the breakdown of physical determinism. Penrose has conjectured (in his `Strong Cosmic Censorship Conjecture`) that it is generically unbounded curvature that causes singularities, rather than causal breakdown. The verification that ``AVTD behavior'' (marked by the domination of time derivatives over space derivatives) is generically present in a family of solutions has proven to be a useful tool for studying model versions of Strong Cosmic Censorship in that family. I discuss some of the history of Strong Cosmic Censorship, and then discuss what is known about AVTD behavior and Strong Cosmic Censorship in families of solutions defined by varying degrees of isometry, and discuss recent results which we believe will extend this knowledge and provide new support for Strong Cosmic Censorship. I also comment on some of the recent work on ``Weak Null Singularities'', and how this relates to Strong Cosmic Censorship.

  8. Strain-Specific Battery of Tests for Domains of Mania: Effects of Valproate, Lithium and Imipramine

    PubMed Central

    Flaisher-Grinberg, Shlomit; Einat, Haim

    2010-01-01

    The lack of efficient animal models for bipolar disorder (BPD), especially for the manic pole, is a major factor hindering the research of its pathophysiology and the development of improved drug treatments. The present study was designed to identify an appropriate mouse strain for modeling some behavioral domains of mania and to evaluate the effects of drugs using this strain. The study compared the behavior of four strains: Black Swiss, C57Bl/6, CBA/J and A/J mice in a battery of tests that included spontaneous activity; sweet solution preference; light/dark box; resident-intruder; forced-swim and amphetamine-induced hyperactivity. Based on the ‘manic-like’ behavior demonstrated by the Black Swiss strain, the study evaluated the effects of the mood stabilizers valproate and lithium and of the antidepressant imipramine in the same tests using this strain. Results indicated that lithium and valproate attenuate the ‘manic-like’ behavior of Black Swiss mice whereas imipramine had no effects. These findings suggest that Black Swiss mice might be a good choice for modeling several domains of mania and distinguishing the effects of drugs on these specific domains. However, the relevance of the behavioral phenotype of Black Swiss mice to the biology of BPD is unknown at this time and future studies will investigate molecular differences between Black Swiss mice and other strains and asess the interaction between strain and mood stabilizing treatment. PMID:21423422

  9. The effect of domain-general inhibition-related training on language switching: An ERP study.

    PubMed

    Liu, Huanhuan; Liang, Lijuan; Dunlap, Susan; Fan, Ning; Chen, Baoguo

    2016-01-01

    Previous studies have demonstrated that inhibitory control ability could be improved by training, and the Inhibitory Control (IC) Model implies that enhanced domain-general inhibition may elicit certain changes in language switch costs. In the present study, we aimed to examine the effects of domain-general inhibition training on performance in a language switching task, including which phase of domain-general inhibitory control benefits from training during an overt picture naming task in L1 and L2, using the event-related brain potentials (ERPs). Results showed that the language switch costs of bilinguals with high inhibitory control (high-IC) were symmetrical in both pretest and posttest, and those of bilinguals with low inhibitory control (low-IC) were asymmetrical in the pretest, but symmetrical in the posttest. Moreover, the high-IC group showed a larger LPC (late positive component) for L2 switch trials than for L1 trials in both pretest and posttest. In contrast, the low-IC group only exhibited a similar pattern of LPC in the posttest, but not in the pretest. These results indicate that inhibition training could increase the efficiency of language switching, and inhibitory control may play a key role during the lexical selection response phase. Overall, the present study is the first one to provide electrophysiological evidence for individual differences in the domain-general inhibition impact on language switching performance in low-proficient bilinguals.

  10. JUPITER AS A GIANT COSMIC RAY DETECTOR

    SciTech Connect

    Rimmer, P. B.; Stark, C. R.; Helling, Ch.

    2014-06-01

    We explore the feasibility of using the atmosphere of Jupiter to detect ultra-high-energy cosmic rays (UHECRs). The large surface area of Jupiter allows us to probe cosmic rays of higher energies than previously accessible. Cosmic ray extensive air showers in Jupiter's atmosphere could in principle be detected by the Large Area Telescope (LAT) on the Fermi observatory. In order to be observed, these air showers would need to be oriented toward the Earth, and would need to occur sufficiently high in the atmosphere that the gamma rays can penetrate. We demonstrate that, under these assumptions, Jupiter provides an effective cosmic ray ''detector'' area of 3.3 × 10{sup 7} km{sup 2}. We predict that Fermi-LAT should be able to detect events of energy >10{sup 21} eV with fluence 10{sup –7} erg cm{sup –2} at a rate of about one per month. The observed number of air showers may provide an indirect measure of the flux of cosmic rays ≳ 10{sup 20} eV. Extensive air showers also produce a synchrotron signature that may be measurable by Atacama Large Millimeter/submillimeter Array (ALMA). Simultaneous observations of Jupiter with ALMA and Fermi-LAT could be used to provide broad constraints on the energies of the initiating cosmic rays.

  11. Reminiscences of cosmic ray research in Mexico

    NASA Astrophysics Data System (ADS)

    Pérez-Peraza, Jorge

    2009-11-01

    Cosmic ray research in Mexico dates from the early 1930s with the work of the pioneering physicist, Manuel Sandoval Vallarta and his students from Mexico. Several experiments of international significance were carried out during that period in Mexico: they dealt with the geomagnetic latitude effect, the north-south and west-east asymmetry of cosmic ray intensity, and the sign of the charge of cosmic rays. The international cosmic ray community has met twice in Mexico for the International Cosmic Ray Conferences (ICRC): the fourth was held in Guanajuato in 1955, and the 30th took place in Mérida, in 2007. In addition, an international meeting on the Pierre Auger Collaboration was held in Morelia in 1999, and the International Workshop on Observing UHE Cosmic Rays took place in Metepec in 2000. A wide range of research topics has been developed, from low-energy Solar Energetic Particles (SEP) to the UHE. Instrumentation has evolved since the early 1950s, from a Simpson type neutron monitor installed in Mexico City (2300 m asl) to a solar neutron telescope and an EAS Cherenkov array, (within the framework of the Auger International Collaboration), both at present operating on Mt. Sierra La Negra in the state of Puebla (4580 m asl). Research collaboration has been undertaken with many countries; in particular, the long-term collaboration with Russian scientists has been very fruitful.

  12. Evaluation of shielding effectiveness of composite wall with a time domain discontinuous Galerkin method

    NASA Astrophysics Data System (ADS)

    Kameni Ntichi, Abelin; Modave, Axel; Boubekeur, Mohamed; Preault, Valentin; Pichon, Lionel; Geuzaine, Christophe

    2013-11-01

    This article presents a time domain discontinuous Galerkin method applied for solving the con-servative form of Maxwells' equations and computing the radiated fields in electromagnetic compatibility problems. The results obtained in homogeneous media for the transverse magnetic waves are validated in two cases. We compare our solution to an analytical solution of Maxwells' equations based on characteristic method. Our results on shielding effectiveness of a conducting wall are same as those obtained from analytical expression in frequency domain. The propagation in heterogeneous medium is explored. The shielding effectiveness of a composite wall partially filled by circular conductives inclusions is computed. The proposed results are in conformity with the classical predictive homogenization rules. Contribution to the Topical Issue "Numelec 2012", Edited by Adel Razek.

  13. Explaining TeV cosmic-ray anisotropies with non-diffusive cosmic-ray propagation

    DOE PAGES

    Harding, James Patrick; Fryer, Chris Lee; Mendel, Susan Marie

    2016-05-11

    Constraining the behavior of cosmic ray data observed at Earth requires a precise understanding of how the cosmic rays propagate in the interstellar medium. The interstellar medium is not homogeneous; although turbulent magnetic fields dominate over large scales, small coherent regions of magnetic field exist on scales relevant to particle propagation in the nearby Galaxy. Guided propagation through a coherent field is significantly different from random particle diffusion and could be the explanation of spatial anisotropies in the observed cosmic rays. We present a Monte Carlo code to propagate cosmic particle through realistic magnetic field structures. We discuss the detailsmore » of the model as well as some preliminary studies which indicate that coherent magnetic structures are important effects in local cosmic-ray propagation, increasing the flux of cosmic rays by over two orders of magnitude at anisotropic locations on the sky. Furthermore, the features induced by coherent magnetic structure could be the cause of the observed TeV cosmic-ray anisotropy.« less

  14. Explaining TeV cosmic-ray anisotropies with non-diffusive cosmic-ray propagation

    SciTech Connect

    Harding, James Patrick; Fryer, Chris Lee; Mendel, Susan Marie

    2016-05-11

    Constraining the behavior of cosmic ray data observed at Earth requires a precise understanding of how the cosmic rays propagate in the interstellar medium. The interstellar medium is not homogeneous; although turbulent magnetic fields dominate over large scales, small coherent regions of magnetic field exist on scales relevant to particle propagation in the nearby Galaxy. Guided propagation through a coherent field is significantly different from random particle diffusion and could be the explanation of spatial anisotropies in the observed cosmic rays. We present a Monte Carlo code to propagate cosmic particle through realistic magnetic field structures. We discuss the details of the model as well as some preliminary studies which indicate that coherent magnetic structures are important effects in local cosmic-ray propagation, increasing the flux of cosmic rays by over two orders of magnitude at anisotropic locations on the sky. Furthermore, the features induced by coherent magnetic structure could be the cause of the observed TeV cosmic-ray anisotropy.

  15. Level crossing analysis of cosmic microwave background radiation: a method for detecting cosmic strings

    SciTech Connect

    Movahed, M. Sadegh; Khosravi, Shahram E-mail: khosravi@ipm.ir

    2011-03-01

    In this paper we study the footprint of cosmic string as the topological defects in the very early universe on the cosmic microwave background radiation. We develop the method of level crossing analysis in the context of the well-known Kaiser-Stebbins phenomenon for exploring the signature of cosmic strings. We simulate a Gaussian map by using the best fit parameter given by WMAP-7 and then superimpose cosmic strings effects on it as an incoherent and active fluctuations. In order to investigate the capability of our method to detect the cosmic strings for the various values of tension, Gμ, a simulated pure Gaussian map is compared with that of including cosmic strings. Based on the level crossing analysis, the superimposed cosmic string with Gμ∼>4 × 10{sup −9} in the simulated map without instrumental noise and the resolution R = 1' could be detected. In the presence of anticipated instrumental noise the lower bound increases just up to Gμ∼>5.8 × 10{sup −9}.

  16. Biomarker response to galactic cosmic ray-induced NOx and the methane greenhouse effect in the atmosphere of an Earth-like planet orbiting an M dwarf star.

    PubMed

    Grenfell, John Lee; Griessmeier, Jean-Mathias; Patzer, Beate; Rauer, Heike; Segura, Antigona; Stadelmann, Anja; Stracke, Barbara; Titz, Ruth; Von Paris, Philip

    2007-02-01

    Planets orbiting in the habitable zone of M dwarf stars are subject to high levels of galactic cosmic rays (GCRs), which produce nitrogen oxides (NOx) in Earth-like atmospheres. We investigate to what extent these NO(Mx) species may modify biomarker compounds such as ozone (O3) and nitrous oxide (N2O), as well as related compounds such as water (H2O) (essential for life) and methane (CH4) (which has both abiotic and biotic sources). Our model results suggest that such signals are robust, changing in the M star world atmospheric column due to GCR NOx effects by up to 20% compared to an M star run without GCR effects, and can therefore survive at least the effects of GCRs. We have not, however, investigated stellar cosmic rays here. CH4 levels are about 10 times higher on M star worlds than on Earth because of a lowering in hydroxyl (OH) in response to changes in the ultraviolet. The higher levels of CH4 are less than reported in previous studies. This difference arose partly because we used different biogenic input. For example, we employed 23% lower CH4 fluxes compared to those studies. Unlike on Earth, relatively modest changes in these fluxes can lead to larger changes in the concentrations of biomarker and related species on the M star world. We calculate a CH4 greenhouse heating effect of up to 4K. O3 photochemistry in terms of the smog mechanism and the catalytic loss cycles on the M star world differs considerably compared with that of Earth.

  17. Nonthermal cosmic neutrino background

    NASA Astrophysics Data System (ADS)

    Chen, Mu-Chun; Ratz, Michael; Trautner, Andreas

    2015-12-01

    We point out that, for Dirac neutrinos, in addition to the standard thermal cosmic neutrino background (C ν B ), there could also exist a nonthermal neutrino background with comparable number density. As the right-handed components are essentially decoupled from the thermal bath of standard model particles, relic neutrinos with a nonthermal distribution may exist until today. The relic density of the nonthermal (nt) background can be constrained by the usual observational bounds on the effective number of massless degrees of freedom Neff and can be as large as nν nt≲0.5 nγ. In particular, Neff can be larger than 3.046 in the absence of any exotic states. Nonthermal relic neutrinos constitute an irreducible contribution to the detection of the C ν B and, hence, may be discovered by future experiments such as PTOLEMY. We also present a scenario of chaotic inflation in which a nonthermal background can naturally be generated by inflationary preheating. The nonthermal relic neutrinos, thus, may constitute a novel window into the very early Universe.

  18. Giant photovoltaic effect of ferroelectric domain walls in perovskite single crystals

    PubMed Central

    Inoue, Ryotaro; Ishikawa, Shotaro; Imura, Ryota; Kitanaka, Yuuki; Oguchi, Takeshi; Noguchi, Yuji; Miyayama, Masaru

    2015-01-01

    The photovoltaic (PV) effect in polar materials offers great potential for light-energy conversion that generates a voltage beyond the bandgap limit of present semiconductor-based solar cells. Ferroelectrics have received renewed attention because of the ability to deliver a high voltage in the presence of ferroelastic domain walls (DWs). In recent years, there has been considerable debate over the impact of the DWs on the PV effects, owing to lack of information on the bulk PV tensor of host ferroelectrics. In this article, we provide the first direct evidence of an unusually large PV response induced by ferroelastic DWs—termed ‘DW’-PV effect. The precise estimation of the bulk PV tensor in single crystals of barium titanate enables us to quantify the giant PV effect driven by 90° DWs. We show that the DW-PV effect arises from an effective electric field consisting of a potential step and a local PV component in the 90° DW region. This work offers a starting point for further investigation into the DW-PV effect of alternative systems and opens a reliable route for enhancing the PV properties in ferroelectrics based on the engineering of domain structures in either bulk or thin-film form. PMID:26443381

  19. tDCS polarity effects in motor and cognitive domains: a meta-analytical review.

    PubMed

    Jacobson, Liron; Koslowsky, Meni; Lavidor, Michal

    2012-01-01

    In vivo effects of transcranial direct current stimulation (tDCS) have attracted much attention nowadays as this area of research spreads to both the motor and cognitive domains. The common assumption is that the anode electrode causes an enhancement of cortical excitability during stimulation, which then lasts for a few minutes thereafter, while the cathode electrode generates the opposite effect, i.e., anodal-excitation and cathodal-inhibition effects (AeCi). Yet, this dual-polarity effect has not been observed in all tDCS studies. Here, we conducted a meta-analytical review aimed to investigate the homogeneity/heterogeneity of the effect sizes of the AeCi dichotomy in both motor and cognitive functions. The AeCi effect was found to occur quite commonly with motor investigations and rarely in cognitive studies. When the anode electrode is applied over a non-motor area, in most cases, it will cause an excitation as measured by a relevant cognitive or perceptual task; however, the cathode electrode rarely causes an inhibition. We found homogeneity in motor studies and heterogeneity in cognitive studies with the electrode's polarity serving as a moderator that can explain the source of heterogeneity in cognitive studies. The lack of inhibitory cathodal effects might reflect compensation processes as cognitive functions are typically supported by rich brain networks. Further insights as to the polarity and domain interaction are offered, including subdivision to different classes of cognitive functions according to their likelihood of being affected by stimulation.

  20. Distinct domains of the limbic system-associated membrane protein (LAMP) mediate discrete effects on neurite outgrowth.

    PubMed

    Eagleson, Kathie L; Pimenta, Aurea F; Burns, Mary M; Fairfull, Liane D; Cornuet, Pamela K; Zhang, Li; Levitt, Pat

    2003-11-01

    The limbic system-associated membrane protein (LAMP) is a glycosylphosphatidylinositol-anchored glycoprotein with three immunoglobulin (Ig) domains that can either enhance or inhibit neurite outgrowth depending upon the neuronal population examined. In the present study, we investigate the domains responsible for these activities. Domain deletion revealed that the N-terminal IgI domain is necessary and sufficient for the neurite-promoting activity observed in hippocampal neurons. In contrast, inhibition of neurite outgrowth in SCG neurons, which is mediated by heterophilic interactions, requires full-length LAMP, although selective inhibition of the second Ig domain, but not the first or third domains, prevented the inhibitory effect. This indicates that the IgII domain of LAMP harbors the neurite-inhibiting activity, but only in the context of the full-length configuration. Covasphere-binding analyses demonstrate IgI/IgI interactions, but no interaction between IgII and any other domain, consistent with the biological activities that each domain mediates. The data suggest that LAMP may serve as a bifunctional guidance molecule, with distinct structural domains contributing to the promotion and inhibition of neurite outgrowth.

  1. The effects of cosmic particle radiation on pocket mice aboard Apollo XVII: IX Results of examination of the nasal mucosa.

    PubMed

    Kraft, L M; Vogel, F S; Lloyd, B; Benton, E V; Cruty, M R; Haymaker, W; Leon, A; Billingham, J; Turnbill, C E; Teas, V; Look, B C; Suri, K; Miquel, J; Ashley, W W; Behnke, A R; Samorajski, T; Bailey, O T; Zeman, W

    1975-04-01

    The olfactory epithelium, but not the nasal respiratory epithelium, of the four pocket mice (Perognathus longimembris) that survived their flight on Apollo XVII showed both diffuse alterations and numerous disseminated focal lesions. The olfactory mucosa of the mouse that died during flight was also affected, but to a minor degree insofar as could be determined. All this was in contrast to the normal appearance of the olfactory mucosa of the numerous control animals. A number of possible causes were considered: systemic or regional infection; inhaled particulate material (seed dust); by-products from the KO2 bed in aerosol or particulate form; gas contaminants originating in the flight package; volatile substances from the dead mouse; weightlessness; and cosmic ray particle radiation. Where feasible, studies were conducted in an effort to rule in or rule out some of these potentially causative factors. No definitive conclusions were reached as to the cause of the lesions in the flight mice.

  2. Predator hunting mode and habitat domain alter nonconsumptive effects in predator-prey interactions.

    PubMed

    Preisser, Evan L; Orrock, John L; Schmitz, Oswald J

    2007-11-01

    Predators can affect prey populations through changes in traits that reduce predation risk. These trait changes (nonconsumptive effects, NCEs) can be energetically costly and cause reduced prey activity, growth, fecundity, and survival. The strength of nonconsumptive effects may vary with two functional characteristics of predators: hunting mode (actively hunting, sit-and-pursue, sit-and-wait) and habitat domain (the ability to pursue prey via relocation in space; can be narrow or broad). Specifically, cues from fairly stationary sit-and-wait and sit-and-pursue predators should be more indicative of imminent predation risk, and thereby evoke stronger NCEs, compared to cues from widely ranging actively hunting predators. Using a meta-analysis of 193 published papers, we found that cues from sit-and-pursue predators evoked stronger NCEs than cues from actively hunting predators. Predator habitat domain was less indicative of NCE strength, perhaps because habitat domain provides less reliable information regarding imminent risk to prey than does predator hunting mode. Given the importance of NCEs in determining the dynamics of prey communities, our findings suggest that predator characteristics may be used to predict how changing predator communities translate into changes in prey. Such knowledge may prove particularly useful given rates of local predator change due to habitat fragmentation and the introduction of novel predators.

  3. Are therapists uniformly effective across patient outcome domains? A study on therapist effectiveness in two different treatment contexts.

    PubMed

    Nissen-Lie, Helene A; Goldberg, Simon B; Hoyt, William T; Falkenström, Fredrik; Holmqvist, Rolf; Nielsen, Stevan Lars; Wampold, Bruce E

    2016-07-01

    As established in several studies, therapists differ in effectiveness. A vital research task now is to understand what characterizes more or less effective therapists, and investigate whether this differential effectiveness systematically depends on client factors, such as the type of mental health problem. The purpose of the current study was to examine whether therapists are universally effective across patient outcome domains reflecting different areas of mental health functioning. Data were obtained from 2 sites: the Research Consortium of Counseling and Psychological Services in Higher Education (N = 5,828) in the United States and from primary and secondary care units (N = 616) in Sweden. Outcome domains were assessed via the Outcome Questionnaire-45 (Lambert et al., 2004) and the CORE-OM (Evans et al., 2002). Multilevel models with observations nested within patients were used to derive a reliable estimate for each patient's change (which we call a multilevel growth d) based on all reported assessment points. Next, 2 multilevel confirmatory factor analytic models were fit in which these effect sizes (multilevel ds) for the 3 subscales of the OQ-45 (Study 1) and 6 subscales of CORE-OM (Study 2) were indicators of 1 common latent factor at the therapist level. In both data sets, such a model, reflecting a global therapist effectiveness factor, yielded large factor loadings and excellent model fit. Results suggest that therapists effective (or ineffective) within one outcome domain are also effective within another outcome domain. Tentatively, therapist effectiveness can thus be conceived of as a global construct. (PsycINFO Database Record

  4. Extending the effective imaging depth in spectral domain optical coherence tomography by dual spatial frequency encoding

    NASA Astrophysics Data System (ADS)

    Wu, Tong; Wang, Qingqing; Liu, Youwen; Wang, Jiming

    2016-03-01

    We present a spatial frequency domain multiplexing method for extending the imaging depth range of a SDOCT system without any expensive device. This method uses two reference arms with different round-trip optical delay to probe different depth regions within the sample. Two galvo scanners with different pivot-offset distances in the reference arms are used for spatial frequency modulation and multiplexing. While simultaneously driving the galvo scanners in the reference arms and the sample arm, the spatial spectrum of the acquired two-dimensional OCT spectral interferogram corresponding to the shallow and deep depth of the sample will be shifted to the different frequency bands in the spatial frequency domain. After data filtering, image reconstruction and fusion the spatial frequency multiplexing SDOCT system can provide an approximately 1.9 fold increase in the effective ranging depth compared with that of a conventional single-reference-arm full-range SDOCT system.

  5. Kondo effect from a Lorentz-violating domain wall description of superconductivity

    NASA Astrophysics Data System (ADS)

    Bazeia, D.; Brito, F. A.; Mota-Silva, J. C.

    2016-11-01

    We extend recent results on domain wall description of superconductivity in an Abelian Higgs model by introducing a particular Lorentz-violating term. The temperature of the system is interpreted through the fact that the soliton following accelerating orbits is a Rindler observer experiencing a thermal bath. We show that this term can be associated with the Kondo effect, that is, the Lorentz-violating parameter is closely related to the concentration of magnetic impurities living on a superconducting domain wall. We also found that the critical temperature decreasing with the impurity concentration as a non-single-valued function, for the case TK

  6. Cosmic questions: an introduction.

    PubMed

    Primack, J R; Abrams, N E

    2001-12-01

    This introductory talk at the Cosmic Questions conference sponsored by the AAAS summarizes some earlier pictures of the universe and some pictures based on modern physics and cosmology. The uroboros (snake swallowing its tail) is an example of a traditional picture. The Biblical flat-earth picture was very different from the Greek spherical earth-centered picture, which was the standard view until the end of the Middle Ages. Many people incorrectly assume that the Newtonian picture of stars scattered through otherwise empty space is still the prevailing view. Seeing Earth from space shows the power of a new picture. The Hubble Space Telescope can see all the bright galaxies, all the way to the cosmic Dark Ages. We are at the center of cosmic spheres of time: looking outward is looking backward in time. All the matter and energy in the universe can be represented as a cosmic density pyramid. The laws of physics only allow the material objects in the universe to occupy a wedge-shaped region on a diagram of mass versus size. All sizes--from the smallest size scale, the Planck scale, to the entire visible universe--can be represented on the Cosmic Uroboros. There are interesting connections across this diagram, and the human scale lies in the middle.

  7. Polycyclic aromatic hydrocarbon processing by cosmic rays

    NASA Astrophysics Data System (ADS)

    Micelotta, E. R.; Jones, A. P.; Tielens, A. G. G. M.

    2011-02-01

    Context. Cosmic rays are present in almost all phases of the ISM. Polycyclic aromatic hydrocarbons (PAHs) and cosmic rays represent an abundant and ubiquitous component of the interstellar medium. However, the interaction between them has never before been fully investigated. Aims: To study the effects of cosmic ray ion (H, He, CNO and Fe-Co-Ni) and electron bombardment of PAHs in galactic and extragalactic environments. Methods: We calculate the nuclear and electronic interactions for collisions between PAHs and cosmic ray ions and electrons with energies between 5 MeV/nucleon and 10 GeV, above the threshold for carbon atom loss, in normal galaxies, starburst galaxies and cooling flow galaxy clusters. Results: The timescale for PAH destruction by cosmic ray ions depends on the electronic excitation energy E0 and on the amount of energy available for dissociation. Small PAHs are destroyed faster, with He and the CNO group being the more effective projectiles. For electron collisions, the lifetime is independent of the PAH size and varies with the threshold energy T0. Conclusions: Cosmic rays process the PAHs in diffuse clouds, where the destruction due to interstellar shocks is less efficient. In the hot gas filling galactic halos, outflows of starburst galaxies and intra-cluster medium, PAH destruction is dominated by collisions with thermal ions and electrons, but this mechanism is ineffective if the molecules are in denser cloudlets and isolated from the hot gas. Cosmic rays can access the denser clouds and together with X-rays will set the lifetime of those protected PAHs. This limits the use of PAHs as a "dye" for tracing the presence of cold entrained material.

  8. Degeneracy between primordial tensor modes and cosmic strings in future CMB data from the Planck satellite

    SciTech Connect

    Urrestilla, Jon; Mukherjee, Pia; Liddle, Andrew R.; Hindmarsh, Mark; Kunz, Martin; Bevis, Neil

    2008-06-15

    While observations indicate that the predominant source of cosmic inhomogeneities are adiabatic perturbations, there are a variety of candidates to provide auxiliary trace effects, including inflation-generated primordial tensors and cosmic defects which both produce B-mode cosmic microwave background polarization. We investigate whether future experiments may suffer confusion as to the true origin of such effects, focusing on the ability of Planck to distinguish tensors from cosmic strings, and show that there is no significant degeneracy.

  9. Investigations of the effects of cosmic rays on Artemia cysts and tobacco seeds; results of Exobloc II experiment, flown aboard Biocosmos 1887.

    PubMed

    Gaubin, Y; Delpoux, M; Pianezzi, B; Gasset, G; Heilmann, C; Planel, H

    1990-01-01

    Artemia (Brine shrimp) cysts and tobacco seeds, dormant biological material devoid of metabolic activity, were flown aboard the Soviet Biocosmos 1887 in order to investigate the effects of cosmic rays. Artemia cysts and tobacco seeds were used in bulk or in monolayers sandwiched with track detectors. Biological and physical units were located outside and inside the spacecraft. Stacks included lead shielding in order to expose the objects to different doses of radiation. Total dosimetry was performed using thermoluminescent detectors. In spite of low levels of doses, the space flight resulted in a decrease in developmental capacity of Artemia cysts, and in a higher mutation rate in tobacco seeds. The more obvious responses occurred, in both cases, in biological objects exposed to the highest doses. These results are compared to those of previous space experiments.

  10. The TRIPLE LUX-A Experiment for BIOLAB/ISS- Combined Effects of Microgravity and Cosmic Radiation on the Oxidative Burst of Mammalian Macrophageal Cells

    NASA Astrophysics Data System (ADS)

    Huber, K.; Sromicki, J.; Hock, B.; Ullrich, O.

    2008-06-01

    Phagocytes, the prominent cells of innate immunity, are responsible for the removal of foreign invaders, apoptotic as well as cancer cells. In a flight experiment in the BIOLAB facility on the ISS we will investigate the combined effects of microgravity and cosmic radiation on the oxidative burst, the production of reactive oxygen species (ROS), of the macrophageal cell line NR8383. A chemiluminescence assay (luminol) is used to determine the amount of ROS during phagocytosis of zymosan in a kinetic approach. Ground control experiments for the TRIPLE LUX-A flight experiment on a fast rotating 2D clinostat showed that the selected cell line responds to simulated weightlessness by an increase of ROS production.

  11. The effects of cosmic particle radiation on pocket mice aboard Apollo XVII: appendix II. Evaluation of oral, dental, and skeletal tissues.

    PubMed

    Person, P; Eversole, L R; Shklar, G; Johnson, L C; Moss, M L

    1975-04-01

    A sparse neutrophilic leukocytic infiltrate was found in the gingival sulcus, both in the flight and the control animals, while no changes were observed in the palate. Mitoses in gingival and palatal tissues were in approximately equal numbers in all animal groups. The tongues of flight mice and controls contained areas characterized by vascular dilatation, separation of muscle bundles, and regressive and degenerative changes in muscle fibers. Mucous glands in the posterior part of the tongue of flight and control animals exhibited acinar distension. Also examined were the vertebral column; femur, knee joint, tibia and fibula of the right hindlimb; and the tracheal cartilages. No evidence of cosmic ray particle effects was found in any of these tissues.

  12. Mapping the Cosmic Dawn

    NASA Astrophysics Data System (ADS)

    Furlanetto, Steven

    The following sections are included: * A Brief History of Our Universe: From Soup to Galaxies * The Hidden Cosmic Dawn * The Solution: Flipping Spins * The Spin-Flip Transition as an Astronomical Tool * Foiled!: Early Cosmology with the Spin-Flip Transition * Spin-Flip Radiation Holds the Key to Observing the Cosmic Dawn * The Spin-Flip Background: The First Stars * The Spin-Flip Background: The First Black Holes * The Spin-Flip Background: The Epoch of Reionization * FM Radio Antennae as Cosmic Observatories * Piles and Tiles of Antennae: Mapping the Spin-Flip Background * Mountains to Scale: Challenges to Observing the Spin-Flip Background * Sound and Fury, Signifying Statistics * An Explosion of Telescopes * Dreams for the Future * An Unfinished Story

  13. Cosmic radiation in commercial aviation.

    PubMed

    Bagshaw, Michael

    2008-05-01

    This paper reviews the current knowledge of cosmic radiation and its applicability to commercial aviation. Galactic cosmic radiation emanates from outside the solar system, while occasionally a disturbance in the suns' atmosphere leads to a surge in radiation particles. Protection is provided by the suns' magnetic field, the earths' magnetic field, and the earths' atmosphere. Dose rates are dependent on the altitude, the geomagnetic latitude and the solar cycle. For occupational exposure to ionising radiation, which includes aircrew, the International Commission on Radiological Protection recommends maximum mean body effective dose limits of 20mSv/yr (averaged over 5 years, with a maximum in any 1 year of 50mSv). Radiation doses can be measured during flight or may be calculated using a computer-modelling program such as CARI, EPCARD, SIEVERT or PCAIRE. Mean ambient equivalent dose rates are consistently reported in the region of 4-5microSv/h for long-haul pilots and 1-3microSv/h for short-haul, giving an annual mean effective exposure of the order 2-3mSv for long-haul and 1-2mSv for short-haul pilots. Epidemiological studies of flight crew have not shown conclusive evidence for any increase in cancer mortality or cancer incidence directly attributable to ionising radiation exposure. Whilst there is no level of radiation exposure below which effects do not occur, current evidence indicates that the probability of airline crew or passengers suffering adverse health effects as a result of exposure to cosmic radiation is very low.

  14. Acoustic instability driven by cosmic-ray streaming

    NASA Astrophysics Data System (ADS)

    Begelman, Mitchell C.; Zweibel, Ellen G.

    1994-08-01

    We study the linear stability of compressional waves in a medium through which cosmic rays stream at the Alfven speed due to strong coupling with Alfven waves. Acoustic waves can be driven unstable by the cosmic-ray drift, provided that the streaming speed is sufficiently large compared to the thermal sound speed. Two effects can cause instability: (1) the heating of the thermal gas due to the damping of Alfven waves driven unstable by cosmic-ray streaming; and (2) phase shifts in the cosmic-ray pressure perturbation caused by the combination of cosmic-ray streaming and diffusion. The instability does not depend on the magnitude of the background cosmic-ray pressure gradient, and occurs whether or not cosmic-ray diffusion is important relative to streaming. When the cosmic-ray pressure is small compared to the gas pressure, or cosmic-ray diffusion is strong, the instability manifests itself as a weak overstability of slow magnetosonic waves. Larger cosmic-ray pressure gives rise to new hybrid modes, which can be strongly unstable in the limits of both weak and strong cosmic-ray diffusion and in the presence of thermal conduction. Parts of our analysis parallel earlier work by McKenzie & Webb (which were brought to our attention after this paper was accepted for publication), but our treatment of diffusive effects, thermal conduction, and nonlinearities represent significant extensions. Although the linear growth rate of instability is independent of the background cosmic-ray pressure gradient, the onset of nonlinear eff ects does depend on absolute value of DEL (vector differential operator) Pc. At the onset of nonlinearity the fractional amplitude of cosmic-ray pressure perturbations is delta PC/PC approximately (kL) -1 much less than 1, where k is the wavenumber and L is the pressure scale height of the unperturbed cosmic rays. We speculate that the instability may lead to a mode of cosmic-ray transport in which plateaus of uniform cosmic-ray pressure are

  15. Acoustic instability driven by cosmic-ray streaming

    NASA Technical Reports Server (NTRS)

    Begelman, Mitchell C.; Zweibel, Ellen G.

    1994-01-01

    We study the linear stability of compressional waves in a medium through which cosmic rays stream at the Alfven speed due to strong coupling with Alfven waves. Acoustic waves can be driven unstable by the cosmic-ray drift, provided that the streaming speed is sufficiently large compared to the thermal sound speed. Two effects can cause instability: (1) the heating of the thermal gas due to the damping of Alfven waves driven unstable by cosmic-ray streaming; and (2) phase shifts in the cosmic-ray pressure perturbation caused by the combination of cosmic-ray streaming and diffusion. The instability does not depend on the magnitude of the background cosmic-ray pressure gradient, and occurs whether or not cosmic-ray diffusion is important relative to streaming. When the cosmic-ray pressure is small compared to the gas pressure, or cosmic-ray diffusion is strong, the instability manifests itself as a weak overstability of slow magnetosonic waves. Larger cosmic-ray pressure gives rise to new hybrid modes, which can be strongly unstable in the limits of both weak and strong cosmic-ray diffusion and in the presence of thermal conduction. Parts of our analysis parallel earlier work by McKenzie & Webb (which were brought to our attention after this paper was accepted for publication), but our treatment of diffusive effects, thermal conduction, and nonlinearities represent significant extensions. Although the linear growth rate of instability is independent of the background cosmic-ray pressure gradient, the onset of nonlinear eff ects does depend on absolute value of DEL (vector differential operator) P(sub c). At the onset of nonlinearity the fractional amplitude of cosmic-ray pressure perturbations is delta P(sub C)/P(sub C) approximately (kL) (exp -1) much less than 1, where k is the wavenumber and L is the pressure scale height of the unperturbed cosmic rays. We speculate that the instability may lead to a mode of cosmic-ray transport in which plateaus of uniform cosmic

  16. Structural Stability of Human Protein Tyrosine Phosphatase ρ Catalytic Domain: Effect of Point Mutations

    PubMed Central

    Knapp, Stefan; Alfano, Ivan; Ardini, Matteo; Stefanini, Simonetta; Chiaraluce, Roberta

    2012-01-01

    Protein tyrosine phosphatase ρ (PTPρ) belongs to the classical receptor type IIB family of protein tyrosine phosphatase, the most frequently mutated tyrosine phosphatase in human cancer. There are evidences to suggest that PTPρ may act as a tumor suppressor gene and dysregulation of Tyr phosphorylation can be observed in diverse diseases, such as diabetes, immune deficiencies and cancer. PTPρ variants in the catalytic domain have been identified in cancer tissues. These natural variants are nonsynonymous single nucleotide polymorphisms, variations of a single nucleotide occurring in the coding region and leading to amino acid substitutions. In this study we investigated the effect of amino acid substitution on the structural stability and on the activity of the membrane-proximal catalytic domain of PTPρ. We expressed and purified as soluble recombinant proteins some of the mutants of the membrane-proximal catalytic domain of PTPρ identified in colorectal cancer and in the single nucleotide polymorphisms database. The mutants show a decreased thermal and thermodynamic stability and decreased activation energy relative to phosphatase activity, when compared to wild- type. All the variants show three-state equilibrium unfolding transitions similar to that of the wild- type, with the accumulation of a folding intermediate populated at ∼4.0 M urea. PMID:22389709

  17. A study of the membrane association and regulatory effect of the phospholemman cytoplasmic domain.

    PubMed

    Hughes, Eleri; Whittaker, Christopher A P; Barsukov, Igor L; Esmann, Mikael; Middleton, David A

    2011-04-01

    Phospholemman (PLM) is a single-span transmembrane protein belonging to the FXYD family of proteins. PLM (or FXYD1) regulates the Na,K-ATPase (NKA) ion pump by altering its affinity for K(+) and Na(+) and by reducing its hydrolytic activity. Structural studies of PLM in anionic detergent micelles have suggested that the cytoplasmic domain, which alone can regulate NKA, forms a partial helix which is stabilized by interactions with the charged membrane surface. This work examines the membrane affinity and regulatory function of a 35-amino acid peptide (PLM(38-72)) representing the PLM cytoplasmic domain. Isothermal titration calorimetry and solid-state NMR measurements confirm that PLM(38-72) associates strongly with highly anionic phospholipid membranes, but the association is weakened substantially when the negative surface charge is reduced to a more physiologically relevant environment. Membrane interactions are also weakened when the peptide is phosphorylated at S68, one of the substrate sites for protein kinases. PLM(38-72) also lowers the maximal velocity of ATP hydrolysis (V(max)) by NKA, and phosphorylation of the peptide at S68 gives rise to a partial recovery of V(max). These results suggest that the PLM cytoplasmic domain populates NKA-associated and membrane-associated states in dynamic equilibrium and that phosphorylation may alter the position of the equilibrium. Interestingly, peptides representing the cytoplasmic domains of two other FXYD proteins, Mat-8 (FXYD3) and CHIF (FXYD4), have little or no interaction with highly anionic phospholipid membranes and have no effect on NKA function. This suggests that the functional and physical properties of PLM are not conserved across the entire FXYD family.

  18. Supernova and cosmic rays

    NASA Technical Reports Server (NTRS)

    Wefel, J. P.

    1981-01-01

    A general overview of supernova astronomy is presented, followed by a discussion of the relationship between SN and galactic cosmic rays. Pre-supernova evolution is traced to core collapse, explosion, and mass ejection. The two types of SN light curves are discussed in terms of their causes, and the different nucleosynthetic processes inside SNs are reviewed. Physical events in SN remnants are discussed. The three main connections between cosmic rays and SNs, the energy requirement, the acceleration mechanism, and the detailed composition of CR, are detailed.

  19. Cosmic strings: Gravitation without local curvature

    SciTech Connect

    Helliwell, T.M.; Konkowski, D.A.

    1987-05-01

    Cosmic strings are very long, thin structures which might stretch over vast reaches of the universe. If they exist, they would have been formed during phase transitions in the very early universe. The space-time surrounding a straight cosmic string is flat but nontrivial: A two-dimensional spatial section is a cone rather than a plane. This feature leads to unique gravitational effects. The flatness of the cone means that many of the gravitational effects can be understood with no mathematics beyond trigonometry. This includes the observational predictions of the double imaging of quasars and the truncation of the images of galaxies.

  20. Nineteenth International Cosmic Ray Conference. SH Sessions, Volume 5

    NASA Technical Reports Server (NTRS)

    Jones, F. C. (Compiler)

    1985-01-01

    Papers submitted for presentation at the 19th International Cosmic Ray Conference are compiled. This volume contains papers addressing cosmic ray gradients in the heliosphere; siderial, diurnal, and long term modulations; geomagnetic and atmospheric effects; cosmogenic nuclides; solar neutrinos; and detection techniques.

  1. Cosmic Needles versus Cosmic Microwave Background Radiation

    NASA Astrophysics Data System (ADS)

    Li, Aigen

    2003-02-01

    It has been suggested by a number of authors that the 2.7 K cosmic microwave background (CMB) radiation might have arisen from the radiation of ``Population III'' objects thermalized by conducting cosmic graphite/iron needle-shaped dust. Due to a lack of an accurate solution to the absorption properties of exceedingly elongated grains, in existing literature which studies the CMB thermalizing process they are generally modeled as (1) needle-like spheroids in terms of the Rayleigh approximation, (2) infinite cylinders, and (3) antennae. We show here that the Rayleigh approximation is not valid since the Rayleigh criterion is not satisfied for highly conducting needles. We also show that the available intergalactic iron dust, if modeled as infinite cylinders, is not sufficient to supply the required opacity at long wavelengths to obtain the observed isotropy and Planckian nature of the CMB. If appealing to the antenna theory, conducting iron needles with exceedingly large elongations ( >104) appear able to provide sufficient opacity to thermalize the CMB within the iron density limit. But the applicability of the antenna theory to exceedingly thin needles of nanometer/micrometer thickness has not yet been verified.

  2. Weak cosmic censorship: as strong as ever.

    PubMed

    Hod, Shahar

    2008-03-28

    Spacetime singularities that arise in gravitational collapse are always hidden inside of black holes. This is the essence of the weak cosmic censorship conjecture. The hypothesis, put forward by Penrose 40 years ago, is still one of the most important open questions in general relativity. In this Letter, we reanalyze extreme situations which have been considered as counterexamples to the weak cosmic censorship conjecture. In particular, we consider the absorption of scalar particles with large angular momentum by a black hole. Ignoring back reaction effects may lead one to conclude that the incident wave may overspin the black hole, thereby exposing its inner singularity to distant observers. However, we show that when back reaction effects are properly taken into account, the stability of the black-hole event horizon is irrefutable. We therefore conclude that cosmic censorship is actually respected in this type of gedanken experiments.

  3. Galactic cosmic rays and nucleosynthesis

    SciTech Connect

    Kiener, Juergen

    2010-03-01

    The nucleosynthesis of the light elements Li, Be and B by galactic cosmic rays is presented. Observations of cosmic rays and the nuclear reactions responsible for Li, Be and B nucleosynthesis are described, followed by some words on propagation. At the end, some open questions concerning galactic cosmic rays are discussed.

  4. THE KINETIC SUNYAEV-ZEL'DOVICH EFFECT AS A PROBE OF THE PHYSICS OF COSMIC REIONIZATION: THE EFFECT OF SELF-REGULATED REIONIZATION

    SciTech Connect

    Park, Hyunbae; Shapiro, Paul R.; Komatsu, Eiichiro; Iliev, Ilian T.; Ahn, Kyungjin; Mellema, Garrelt

    2013-06-01

    We calculate the angular power spectrum of the cosmic microwave background temperature fluctuations induced by the kinetic Sunyaev-Zel'dovich (kSZ) effect from the epoch of reionization (EOR). We use detailed N-body+radiative-transfer simulations to follow inhomogeneous reionization of the intergalactic medium. For the first time, we take into account the ''self-regulation'' of reionization: star formation in low-mass dwarf galaxies (10{sup 8} M{sub Sun} {approx}< M {approx}< 10{sup 9} M{sub Sun }) or minihalos (10{sup 5} M{sub Sun} {approx}< M {approx}< 10{sup 8} M{sub Sun }) is suppressed if these halos form in the regions that were already ionized or Lyman-Werner dissociated. Some previous work suggested that the amplitude of the kSZ power spectrum from the EOR can be described by a two-parameter family: the epoch of half-ionization and the duration of reionization. However, we argue that this picture applies only to simple forms of the reionization history which are roughly symmetric about the half-ionization epoch. In self-regulated reionization, the universe begins to be ionized early, maintains a low level of ionization for an extended period, and then finishes reionization as soon as high-mass atomically cooling halos dominate. While inclusion of self-regulation affects the amplitude of the kSZ power spectrum only modestly ({approx}10%), it can change the duration of reionization by a factor of more than two. We conclude that the simple two-parameter family does not capture the effect of a physical, yet complex, reionization history caused by self-regulation. When added to the post-reionization kSZ contribution, our prediction for the total kSZ power spectrum is below the current upper bound from the South Pole Telescope. Therefore, the current upper bound on the kSZ effect from the EOR is consistent with our understanding of the physics of reionization.

  5. The effects of cosmic particle radiation on pocket mice aboard Apollo XVII: X. Results of ear examination.

    PubMed

    Haymaker, W; Leon, H A; Barrows, W F; Suri, K; Kraft, L M; Turnbill, C E; Webster, D B; Ashley, W W; Look, B C; Simmonds, R C; Cooper, W; Platt, W T; Behnke, A R; Erway, L C; Cruty, M R; Benton, E V; Ellis, J T; Bailey, O T; Vogel, F S; Lloyd, B; Zeman, W; Billingham, J; Samorajski, T

    1975-04-01

    In the five pocket mice flown on Apollo XVII, no evidence was found that the inner ear had been damaged, though poor fixation precluded detailed study. On the other hand, the middle ear cavity was involved in all the mice, hemorrhage having occurrred in response to excursions in pressure within the canister that housed the mice during their flight. The same occurred in flight control mice which had been subjected to pressure excursions of much the same magnitude. A greater degree of exudation into air cells and greater leukotaxis were noted in the flight animals than in the control animals. There was no increase in leukocyte population along the paths of the 23 cosmic ray particles registered in the subscalp dosimeters that traversed the middle ear cavities of the flight mice. The increased exudation and the greater response by leukocytes in the flight mice may have been causally related to the lesions found in their olfactory mucosa but there were no data in support of this possibility.

  6. The effects of cosmic particle radiation on pocket mice aboard Apollo XVII: appendix III. evaluation of viscera and other tissues.

    PubMed

    Ellis, J T; Kraft, L M; Lushbaugh, C C; Humason, G L; Hartroft, W S; Porta, E A; Bailey, O T; Greep, R O; Leach, C S; Laird, T; Simmonds, R C; Vogel, F S; Dennis, R L; Brashear, H R; Talmage, R V; Harrison, G A; Corbett, R L; Klein, G; Tilbury, T; Suri, K; Haymaker, W

    1975-04-01

    Histopathological findings in the lungs, livers, bone marrows, small intestines, gonads, kidneys, and other tissues of the four pocket mice (Perognathus longimembris) that survived the Apollo XVII flight were evaluated in the light of their immediate environment and as targest of HZE cosmic ray particles. Results of this study failed to disclose changes that could be ascribed to the HZE particle radiation. Decreased numbers of erythropoietic cells in the bone marrow of the flight mice were probably related to the increased oxygen pressure. The small intestine showed no changes. Ovaries and tests appeared normal. Two of the three surviving male flight mice displayed early stages of spermatogenesis, just as ground-based controls did at the same season. Abnormalities were also not found in the thyroid, parathyroids, adrenals, or kidneys. The status of the juxtaglomerular apparatus could not be evaluated. The lungs exhibited nonspecific slight rections. A variety of incidental lesions were noted in the livers of both the flight mice and their controls. The heart muscle showed nothing that could be regarded as pathological. Sections of skeletal muscle examined were free from significant change.

  7. Stages and Conformations of the Tau Repeat Domain during Aggregation and Its Effect on Neuronal Toxicity*

    PubMed Central

    Kumar, Satish; Tepper, Katharina; Kaniyappan, Senthilvelrajan; Biernat, Jacek; Wegmann, Susanne; Mandelkow, Eva-Maria; Müller, Daniel J.; Mandelkow, Eckhard

    2014-01-01

    Several neurodegenerative diseases are characterized by the aggregation and posttranslational modifications of Tau protein. Its “repeat domain” (TauRD) is mainly responsible for the aggregation properties, and oligomeric forms are thought to dominate the toxic effects of Tau. Here we investigated the conformational transitions of this domain during oligomerization and aggregation in different states of β-propensity and pseudo-phosphorylation, using several complementary imaging and spectroscopic methods. Although the repeat domain generally aggregates more readily than full-length Tau, its aggregation was greatly slowed down by phosphorylation or pseudo-phosphorylation at the KXGS motifs, concomitant with an extended phase of oligomerization. Analogous effects were observed with pro-aggregant variants of TauRD. Oligomers became most evident in the case of the pro-aggregant mutant TauRDΔK280, as monitored by atomic force microscopy, and the fluorescence lifetime of Alexa-labeled Tau (time-correlated single photon counting (TCSPC)), consistent with its pronounced toxicity in mouse models. In cell models or primary neurons, neither oligomers nor fibrils of TauRD or TauRDΔK280 had a toxic effect, as seen by assays with lactate dehydrogenase and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, respectively. However, oligomers of pro-aggregant TauRDΔK280 specifically caused a loss of spine density in differentiated neurons, indicating a locally restricted impairment of function. PMID:24825901

  8. The effects of acute aerobic activity on cognition and cross-domain transfer to eating behavior.

    PubMed

    Lowe, Cassandra J; Hall, Peter A; Vincent, Corita M; Luu, Kimberley

    2014-01-01

    Prior studies have demonstrated that a single session of aerobic exercise can enhance cognitive functioning; specifically, the inhibition facet of executive function (EF). Additionally, previous research has demonstrated that inhibitory abilities are essential for effective dietary self-control. However, it is currently unknown whether exercise induced enhancements in EF also facilitate self-control in the dietary domain. The present study sought to determine whether a single session of aerobic exercise enhances EF, and whether there is a transfer effect to dietary self-control. Thirty four undergraduate students were randomly assigned to one of three exercise conditions: (1) minimal exercise; (2) moderate intensity exercise (30% heart rate reserve); (3) vigorous intensity exercise (50% heart rate reserve). After the exercise bout, participants completed three standardized EF tasks followed by a bogus taste test for three appetitive snack foods (milk chocolate and potato chips) and two control foods (dark chocolate and crackers). The amount of food consumed during the taste test was covertly measured. The results revealed a significant main effect of treatment condition on the Stroop task performance, but not Go-NoGo (GNG) and Stop Signal task performance. Findings with respect to food consumption revealed that EF moderated the treatment effect, such that those with larger exercise effects on Stroop performance in the moderate intensity exercise condition consumed more control foods (but not less appetitive foods). These findings support the contention that a single bout of aerobic exercise enhances EF, and may have transfer effects to the dietary domain, but that such effects may be indirect in nature.

  9. Our Cosmic Connection

    ERIC Educational Resources Information Center

    Young, Donna L.

    2005-01-01

    To help students understand the connection that Earth and the solar system have with the cosmic cycles of stellar evolution, and to give students an appreciation of the beauty and elegance of celestial phenomena, the Chandra X-Ray Center (CXC) educational website contains a stellar evolution module that is available free to teachers. In this…

  10. Dominant-negative effect on adhesion by myelin Po protein truncated in its cytoplasmic domain

    PubMed Central

    1996-01-01

    The myelin Po protein is believed to hold myelin together via interactions of both its extracellular and cytoplasmic domains. We have already shown that the extracellular domains of Po can interact in a homophilic manner (Filbin, M.T., F.S. Walsh, B.D. Trapp, J.A. Pizzey, and G.I. Tennekoon. 1990. Nature (Lond.). 344:871-872). In addition, we have shown that for this homophilic adhesion to take place, the cytoplasmic domain of Po must be intact and most likely interacting with the cytoskeleton; Po proteins truncated in their cytoplasmic domains are not adhesive (Wong, M.H., and M.T. Filbin, 1994. J. Cell Biol. 126:1089-1097). To determine if the presence of these truncated forms of Po could have an effect on the functioning of the full-length Po, we coexpressed both molecules in CHO cells. The adhesiveness of CHO cells expressing both full-length Po and truncated Po was then compared to cells expressing only full-length Po. In these coexpressors, both the full-length and the truncated Po proteins were glycosylated. They reached the surface of the cell in approximately equal amounts as shown by an ELISA and surface labeling, followed by immunoprecipitation. Furthermore, the amount of full-length Po at the cell surface was equivalent to other cell lines expressing only full-length Po that we had already shown to be adhesive. Therefore, there should be sufficient levels of full-length Po at the surface of these coexpressors to measure adhesion of Po. However, as assessed by an aggregation assay, the coexpressors were not adhesive. By 60 min they had not formed large aggregates and were indistinguishable from the control transfected cells not expressing Po. In contrast, in the same time, the cells expressing only the full-length Po had formed large aggregates. This indicates that the truncated forms of Po have a dominant-negative effect on the adhesiveness of the full-length Po. Furthermore, from cross-linking studies, full-length Po, when expressed alone but not when

  11. Effect of Multimerization on Membrane Association of Rous Sarcoma Virus and HIV-1 Matrix Domain Proteins

    PubMed Central

    Dick, Robert A.; Kamynina, Elena

    2013-01-01

    In most retroviruses, plasma membrane (PM) association of the Gag structural protein is a critical step in viral assembly, relying in part on interaction between the highly basic Gag MA domain and the negatively charged inner leaflet of the PM. Assembly is thought to begin with Gag dimerization followed by multimerization, resulting in a hexameric lattice. To directly address the role of multimerization in membrane binding, we fused the MA domains of Rous sarcoma virus (RSV) and HIV-1 to the chemically inducible dimerization domain FK506-binding protein (FKBP) or to the hexameric protein CcmK4 from cyanobacteria. The cellular localization of the resulting green fluorescent protein (GFP)-tagged chimeric proteins was examined by fluorescence imaging, and the association of the proteins with liposomes was quantified by flotation in sucrose gradients, following synthesis in a reticulocyte extract or as purified proteins. Four lipid compositions were tested, representative of liposomes commonly reported in flotation experiments. By themselves, GFP-tagged RSV and HIV-1 MA proteins were largely cytoplasmic, but both hexamerized proteins were highly concentrated at the PM. Dimerization led to partial PM localization for HIV-1 MA. These in vivo effects of multimerization were reproduced in vitro. In flotation analyses, the intact RSV and HIV-1 Gag proteins were more similar to multimerized MA than to monomeric MA. RNA is reported to compete with acidic liposomes for HIV-1 Gag binding, and thus we also examined the effects of RNase treatment or tRNA addition on flotation. tRNA competed with liposomes in the case of some but not all lipid compositions and ionic strengths. Taken together, our results further underpin the model that multimerization is critical for PM association of retroviral Gag proteins. In addition, they suggest that the modulation of membrane binding by RNA, as previously reported for HIV-1, may not hold for RSV. PMID:24109216

  12. Cosmic Rays at Earth

    NASA Astrophysics Data System (ADS)

    Grieder, P. K. F.

    In 1912 Victor Franz Hess made the revolutionary discovery that ionizing radiation is incident upon the Earth from outer space. He showed with ground-based and balloon-borne detectors that the intensity of the radiation did not change significantly between day and night. Consequently, the sun could not be regarded as the sources of this radiation and the question of its origin remained unanswered. Today, almost one hundred years later the question of the origin of the cosmic radiation still remains a mystery. Hess' discovery has given an enormous impetus to large areas of science, in particular to physics, and has played a major role in the formation of our current understanding of universal evolution. For example, the development of new fields of research such as elementary particle physics, modern astrophysics and cosmology are direct consequences of this discovery. Over the years the field of cosmic ray research has evolved in various directions: Firstly, the field of particle physics that was initiated by the discovery of many so-called elementary particles in the cosmic radiation. There is a strong trend from the accelerator physics community to reenter the field of cosmic ray physics, now under the name of astroparticle physics. Secondly, an important branch of cosmic ray physics that has rapidly evolved in conjunction with space exploration concerns the low energy portion of the cosmic ray spectrum. Thirdly, the branch of research that is concerned with the origin, acceleration and propagation of the cosmic radiation represents a great challenge for astrophysics, astronomy and cosmology. Presently very popular fields of research have rapidly evolved, such as high-energy gamma ray and neutrino astronomy. In addition, high-energy neutrino astronomy may soon initiate as a likely spin-off neutrino tomography of the Earth and thus open a unique new branch of geophysical research of the interior of the Earth. Finally, of considerable interest are the biological

  13. Electrical detection of magnetic domain walls by inverse and direct spin Hall effect

    NASA Astrophysics Data System (ADS)

    Pham, V. T.; Zahnd, G.; Marty, A.; Savero Torres, W.; Jamet, M.; Noël, P.; Vila, L.; Attané, J. P.

    2016-11-01

    Domain wall (DW) detection is a prerequisite to perform current-induced DW motion. In this letter, we demonstrate a detection method, based on the ability for a ferromagnetic nanowire, in which a DW is pinned, to inject or detect a pure spin current. The device consists of such a ferromagnetic nanowire in contact with an orthogonal spin Hall effect (SHE) nanowire. When a current flows along the ferromagnetic nanowire, and provided a DW is pinned, the pure spin current is transformed into a transverse voltage by inverse spin Hall effect (ISHE). In the reciprocal configuration, the pure spin current created by the direct SHE, generates a transverse voltage along the ferromagnetic wire. Finite element method (FEM) simulations allow estimating the Pt spin Hall angle (SHA) (7.5 ± 0.5%). This technique provides an electrical way to study the DW motion, a device akin to the ferromagnetic/spin Hall effect bilayers typically used for spin-orbit torques experiments.

  14. The effect of surface tethering on the folding of the src-SH3 protein domain

    NASA Astrophysics Data System (ADS)

    Zhuang, Zhuoyun; Jewett, Andrew I.; Soto, Patricia; Shea, Joan-Emma

    2009-03-01

    The effect of surface tethering on the folding mechanism of the src-SH3 protein domain was investigated using a coarse-grained Gō-type protein model. The protein was tethered at various locations along the protein chain and the thermodynamics and kinetics of folding were studied using replica exchange and constant temperature Langevin dynamics. Our simulations reveal that tethering in a structured part of the transition state can dramatically alter the folding mechanism, while tethering in an unstructured part leaves the folding mechanism unaltered as compared to bulk folding. Interestingly, there is only modest correlation between the tethering effect on the folding mechanism and its effect on thermodynamic stability and folding rates. We suggest locations on the protein at which tethering could be performed in single-molecule experiments so as to leave the folding mechanism unaltered from the bulk.

  15. IP effects on electromagnetic data of deep-sea hydrothermal deposits in time domain

    NASA Astrophysics Data System (ADS)

    KIM, H. J.; Jang, H.; Ha, W.

    2015-12-01

    A transient electromagnetic (TEM) system using a small loop source is advantageous to the development of compact, autonomous instruments which are well suited to submersible-based surveys. Since electrical conductivity of subseafloor materials can be frequency dependent, these induced polarization (IP) effects may affect the reliability of TEM data interpretation. In this study, we investigate IP effects on TEM responses of deep-sea hydrothermal mineral deposits with a thin sediment cover. Time-domain target signals are larger and appear earlier in horizontal magnetic fields than in vertical ones. IP effects cause transient magnetic fields to enhance initially, to decay rapidly and then to reverse the polarity. The DC conductivity and IP chargeability in Cole-Cole parameters influence the time of sign reversal and the enhancement of the target response, simultaneously. The reversal time is almost invariant with the time constant while the target signal is almost invariant with the frequency exponent.

  16. Effect of bird maneuver on frequency-domain helicopter EM response

    USGS Publications Warehouse

    Fitterman, D.V.; Yin, C.

    2004-01-01

    Bird maneuver, the rotation of the coil-carrying instrument pod used for frequency-domain helicopter electromagnetic surveys, changes the nominal geometric relationship between the bird-coil system and the ground. These changes affect electromagnetic coupling and can introduce errors in helicopter electromagnetic, (HEM) data. We analyze these effects for a layered half-space for three coil configurations: vertical coaxial, vertical coplanar, and horizontal coplanar. Maneuver effect is shown to have two components: one that is purely geometric and another that is inductive in nature. The geometric component is significantly larger. A correction procedure is developed using an iterative approach that uses standard HEM inversion routines. The maneuver effect correction reduces inversion misfit error and produces laterally smoother cross sections than obtained from uncorrected data. ?? 2004 Society of Exploration Geophysicists. All rights reserved.

  17. 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)

  18. Effects of grain size and disorder on domain wall propagation in CoFeB thin films

    NASA Astrophysics Data System (ADS)

    Voto, Michele; Lopez-Diaz, Luis; Torres, Luis

    2016-05-01

    Micromagnetic simulations are used to investigate the effect of disorder on field-driven domain wall motion in perpendicularly magnetized CoFeB thin films. It is found that some degree of inhomogeneity in the form of an irregular grain structure needs to be introduced in the model in order to account for the domain wall velocities measured experimentally, even for applied fields much larger than the finite propagation field induced by weak disorder in the film. Moreover, the details of this grain structure have a large impact on domain wall motion in this flow regime. In particular, it is found that, for a fixed applied field, domain wall velocity rapidly increases with grain size up to a diameter of 40 nm, above which it slowly decreases. This is explained showing that the grain structure of the material introduces a new form of dissipation of energy via spin wave emission during domain wall propagation. We focus on the relation between grain size and domain wall velocity, finding that the frequency of emission of spin waves packets during domain wall motion depends on the grain size and affects directly the domain wall velocity of propagation.

  19. Neutron irradiation effects on domain wall mobility and reversibility in lead zirconate titanate thin films

    SciTech Connect

    Graham, Joseph T.; Brennecka, Geoff L.; Ihlefeld, Jon F.; Ferreira, Paulo; Small, Leo; Duquette, David; Apblett, Christopher; Landsberger, Sheldon

    2013-03-28

    The effects of neutron-induced damage on the ferroelectric properties of thin film lead zirconate titanate (PZT) were investigated. Two sets of PbZr{sub 0.52}Ti{sub 0.48}O{sub 3} films of varying initial quality were irradiated in a research nuclear reactor up to a maximum 1 MeV equivalent neutron fluence of (5.16 {+-} 0.03) Multiplication-Sign 10{sup 15} cm{sup -2}. Changes in domain wall mobility and reversibility were characterized by polarization-electric field measurements, Rayleigh analysis, and analysis of first order reversal curves (FORC). With increasing fluence, extrinsic contributions to the small-signal permittivity diminished. Additionally, redistribution of irreversible hysterons towards higher coercive fields was observed accompanied by the formation of a secondary hysteron peak following exposure to high fluence levels. The changes are attributed to the radiation-induced formation of defect dipoles and other charged defects, which serve as effective domain wall pinning sites. Differences in damage accumulation rates with initial film quality were observed between the film sets suggesting a dominance of pre-irradiation microstructure on changes in macroscopic switching behavior.

  20. Effect of microwaves on domain wall motion in thin Ni wires

    NASA Astrophysics Data System (ADS)

    Hong, Kimin; Giordano, N.

    1996-03-01

    We report new results on domain wall motion in thin (width and thickness ~ 300 ÅNi wires. The magnetoresistance exhibits discontinuities which we believe are associated with pinning and de-pinning of walls from structural defects, such as variations in the width of the sample. Upon repeated measurement, the de-pinning is found to occur over a narrow range of fields. The distribution of de-pinning fields, P(H), varies with temperature in a manner which suggests that de-pinning occurs via thermal activation at high temperatures, and quantum tunneling at low temperatures, with crossover between these two regimes at T ~ 2 - 6 K. We have also investigated the effect of a 30 GHz microwave field on P(H). In the thermal activation regime, microwaves have no effect on P(H), except through Joule heating. However, in the tunneling regime microwaves cause P(H) to split into several separate peaks. This behavior cannot be explained in terms of Joule heating, but suggests that the energy levels of a domain wall in a pinning well are quantized.

  1. Cosmic Microwave Background Bispectrum from Recombination

    NASA Astrophysics Data System (ADS)

    Huang, Zhiqi; Vernizzi, Filippo

    2013-03-01

    We compute the cosmic microwave background temperature bispectrum generated by nonlinearities at recombination on all scales. We use CosmoLib2nd, a numerical Boltzmann code at second order to compute cosmic microwave background bispectra on the full sky. We consistently include all effects except gravitational lensing, which can be added to our result using standard methods. The bispectrum is peaked on squeezed triangles and agrees with the analytic approximation in the squeezed limit at the few percent level for all the scales where this is applicable. On smaller scales, we recover previous results on perturbed recombination. For cosmic-variance limited data to lmax⁡=2000, its signal-to-noise ratio is S/N=0.47, corresponding to fNLeff=-2.79, and will bias a local signal by fNLloc≃0.82.

  2. Measuring anisotropies in the cosmic neutrino background

    NASA Astrophysics Data System (ADS)

    Lisanti, Mariangela; Safdi, Benjamin R.; Tully, Christopher G.

    2014-10-01

    Neutrino capture on tritium has emerged as a promising method for detecting the cosmic neutrino background (C ν B ). We show that relic neutrinos are captured most readily when their spin vectors are antialigned with the polarization axis of the tritium nuclei and when they approach along the direction of polarization. As a result, C ν B observatories may measure anisotropies in the cosmic neutrino velocity and spin distributions by polarizing the tritium targets. A small dipole anisotropy in the C ν B is expected due to the peculiar velocity of the lab frame with respect to the cosmic frame and due to late-time gravitational effects. The PTOLEMY experiment, a tritium observatory currently under construction, should observe a nearly isotropic background. This would serve as a strong test of the cosmological origin of a potential signal. The polarized-target measurements may also constrain nonstandard neutrino interactions that would induce larger anisotropies and help discriminate between Majorana versus Dirac neutrinos.

  3. THE COSMIC-RAY INTENSITY NEAR THE ARCHEAN EARTH

    SciTech Connect

    Cohen, O.; Drake, J. J.; Kota, J.

    2012-11-20

    We employ three-dimensional state-of-the-art magnetohydrodynamic models of the early solar wind and heliosphere and a two-dimensional model for cosmic-ray transport to investigate the cosmic-ray spectrum and flux near the Archean Earth. We assess how sensitive the cosmic-ray spectrum is to changes in the sunspot placement and magnetic field strength, the large-scale dipole magnetic field strength, the wind ram pressure, and the Sun's rotation period. Overall, our results confirm earlier work that suggested the Archean Earth would have experienced a greatly reduced cosmic-ray flux than is the case today. The cosmic-ray reduction for the early Sun is mainly due to the shorter solar rotation period and tighter winding of the Parker spiral, and to the different surface distribution of the more active solar magnetic field. These effects lead to a global reduction of the cosmic-ray flux at 1 AU by up to two orders of magnitude or more. Variations in the sunspot magnetic field have more effect on the flux than variations in the dipole field component. The wind ram pressure affects the cosmic-ray flux through its influence on the size of the heliosphere via the pressure balance with the ambient interstellar medium. Variations in the interstellar medium pressure experienced by the solar system in orbit through the Galaxy could lead to order of magnitude changes in the cosmic-ray flux at Earth on timescales of a few million years.

  4. Cosmic Coincidences: Investigations for Neutron Background Suppression

    PubMed Central

    Heimbach, Craig R.

    2007-01-01

    Two experimental investigations were made in order to reduce background counts in neutron detectors. Each investigation relied upon the fact that neutron background is largely due to cosmic ray interactions with the air and ground. The first attempt was to look at neutron arrival times. Neutron events close in time were taken to have been of a common origin due to cosmic rays. The second investigation was similar, but based on coincident neutron/muon events. The investigations showed only a small effect, not practical for the suppression of neutron background. PMID:27110457

  5. Cosmic Coincidences: Investigations for Neutron Background Suppression.

    PubMed

    Heimbach, Craig R

    2007-01-01

    Two experimental investigations were made in order to reduce background counts in neutron detectors. Each investigation relied upon the fact that neutron background is largely due to cosmic ray interactions with the air and ground. The first attempt was to look at neutron arrival times. Neutron events close in time were taken to have been of a common origin due to cosmic rays. The second investigation was similar, but based on coincident neutron/muon events. The investigations showed only a small effect, not practical for the suppression of neutron background.

  6. Heliosphere Dimension and Cosmic Ray Modulation

    NASA Astrophysics Data System (ADS)

    Bobik, P.; Boschini, M. J.; Consolandi, C.; Della Torre, S.; Gervasi, M.; Grandi, D.; Kudela, K.; Noventa, F.; Pensotti, S.; Rancoita, P. G.; Rozza, D.

    2012-08-01

    The differential intensities of Cosmic Rays at Earth were calculated using a 2D stochastic Montecarlo diffusion code and compared with observation data. We evaluated the effect of stretched and compressed heliospheres on the Cosmic Ray intensities at the Earth. This was studied introducing a dependence of the diffusion parameter on the heliospherical size. Then, we found that the optimum value of the heliospherical radius better accounting for experimental data. We also found that the obtained values depends on solar activity. Our results are compatible with Voyager observations and with models of heliospherical size modulation.

  7. The biological effectiveness of HZE-particles of cosmic radiation studied in the Apollo 16 and 17 Biostack experiments.

    PubMed

    Bucker, H; Horneck, G

    1975-01-01

    The Biostack experiments I and II were flown on board the Apollo 16 and 17 command modules in order to obtain information on the biological damage produced by the bombardment of heavy high-energy (HZE) particles of cosmic radiation during spaceflight. Such data are required for estimating radiation hazards in manned spaceflight. Seven biological systems in resting state (Bacillus subtilis spores, Colpoda cucullus cysts, Arabidopsis thaliana seeds, and eggs of Artemia salina, Tribolium castaneum and of Carausius morosus) were accommodated in the two Biostacks. By using a special sandwich construction of visual track detectors and layers of biological objects, identification of each hit biological object was achieved and the possible biological damage correlated with the physical features of the responsible HZE-particle. In the different systems the degree of damage depended on whether the hit cell was replaceable or not. A high sensitivity to HZE-particle bombardment was observed on Artemia salina eggs; 90% of the embryos, which were induced to develop from hit eggs, died at different developmental stages. Malformations of the abdomen or the extremities of the nauplius were frequently induced. In contrast, the growth of hit Vicia faba radiculae and the germination of hit Arabidopsis thaliana seeds and hit Bacillus subtilis spores were not influenced remarkably. But there was an increase in multicaulous plants and a reduction in the outgrowth of the bacterial spores. In addition, information was obtained on the fluence of the HZE-particles, on their spectrum of charge and energy loss, and on the absorption by the Apollo spacecraft and the Biostack material itself. This will help to improve knowledge concerning radiation conditions inside of spacecrafts, necessary to secure a maximum possible protection to the astronauts.

  8. Understanding the large-scale structure from the cosmic microwave background: shear calibration with CMB lensing; gas physics from the kinematic Sunyaev-Zel'dovich effect

    NASA Astrophysics Data System (ADS)

    Schaan, Emmanuel

    2017-01-01

    I will present two promising ways in which the cosmic microwave background (CMB) sheds light on critical uncertain physics and systematics of the large-scale structure. Shear calibration with CMB lensing: Realizing the full potential of upcoming weak lensing surveys requires an exquisite understanding of the errors in galaxy shape estimation. In particular, such errors lead to a multiplicative bias in the shear, degenerate with the matter density parameter and the amplitude of fluctuations. Its redshift-evolution can hide the true evolution of the growth of structure, which probes dark energy and possible modifications to general relativity. I will show that CMB lensing from a stage 4 experiment (CMB S4) can self-calibrate the shear for an LSST-like optical lensing survey. This holds in the presence of photo-z errors and intrinsic alignment. Evidence for the kinematic Sunyaev-Zel'dovich (kSZ) effect; cluster energetics: Through the kSZ effect, the baryon momentum field is imprinted on the CMB. I will report significant evidence for the kSZ effect from ACTPol and peculiar velocities reconstructed from BOSS. I will present the prospects for constraining cluster gas profiles and energetics from the kSZ effect with SPT-3G, AdvACT and CMB S4. This will provide constraints on galaxy formation and feedback models.

  9. Hot Spot Cosmic Accelerators

    NASA Astrophysics Data System (ADS)

    2002-11-01

    length of more than 3 million light-years, or no less than one-and-a-half times the distance from the Milky Way to the Andromeda galaxy, this structure is indeed gigantic. The region where the jets collide with the intergalactic medium are known as " hot spots ". Superposing the intensity contours of the radio emission from the southern "hot spot" on a near-infrared J-band (wavelength 1.25 µm) VLT ISAAC image ("b") shows three distinct emitting areas; they are even better visible on the I-band (0.9 µm) FORS1 image ("c"). This emission is obviously associated with the shock front visible on the radio image. This is one of the first times it has been possible to obtain an optical/near-IR image of synchrotron emission from such an intergalactic shock and, thanks to the sensitivity and image sharpness of the VLT, the most detailed view of its kind so far . The central area (with the strongest emission) is where the plasma jet from the galaxy centre hits the intergalactic medium. The light from the two other "knots", some 10 - 15,000 light-years away from the central "hot spot", is also interpreted as synchrotron emission. However, in view of the large distance, the astronomers are convinced that it must be caused by electrons accelerated in secondary processes at those sites . The new images thus confirm that electrons are being continuously accelerated in these "knots" - hence called "cosmic accelerators" - far from the galaxy and the main jets, and in nearly empty space. The exact physical circumstances of this effect are not well known and will be the subject of further investigations. The present VLT-images of the "hot spots" near 3C 445 may not have the same public appeal as some of those beautiful images that have been produced by the same instruments during the past years. But they are not less valuable - their unusual importance is of a different kind, as they now herald the advent of fundamentally new insights into the mysteries of this class of remote and active

  10. Investigation of the Effect of Bilayer Composition on PKCα-C2 Domain Docking Using Molecular Dynamics Simulations.

    PubMed

    Alwarawrah, Mohammad; Wereszczynski, Jeff

    2017-01-12

    The protein kinase Cα (PKCα) enzyme is a member of a broad family of serine/threonine kinases, which are involved in varied cellular signaling pathways. The initial step of PKCα activation involves the C2 subunit docking with the cell membrane, which is followed by interactions of the C1 domains with diacylglycerol (DAG) in the membrane. Notably, the molecular mechanisms of these interactions remain poorly understood, especially what effects, if any, DAG may have on the initial C2 docking. To further understand this process, we have performed a series of conventional molecular dynamics simulations to systematically investigate the interaction between PKCα-C2 domains and lipid bilayers with different compositions to examine the effects of POPS, PIP2, and 1-palmitoyl-2-oleoyl-sn-glycerol (POG) on domain docking. Our results show that the PKCα-C2 domain does not interact with the bilayer surface in the absence of POPS and PIP2. In contrast, the inclusion of POPS and PIP2 to the bilayer resulted in strong domain docking in both perpendicular and parallel orientations, whereas the further inclusion of POG resulted in only parallel domain docking. In addition, lysine residues in the C2 domain formed hydrogen bonds with PIP2 molecule bilayers containing POG. These effects were further explored with umbrella sampling calculations to estimate the free energy of domain docking to the lipid bilayer in the presence of one or two PIP2 molecules. The results show that the binding of one or two PIP2 molecules is thermodynamically favorable, although stronger in bilayers lacking POG. However, in POG-containing bilayers, the binding mode of the C2 domain appears to be more flexible, which may have implications for activation of full-length PKCα. Together, our results shed new insights into the process of C2 bilayer binding and suggest new mechanisms for the roles of different phospholipids in the activation process of PKCα.

  11. Modeling and analysis of polarization effects in Fourier domain mode-locked lasers.

    PubMed

    Jirauschek, Christian; Huber, Robert

    2015-05-15

    We develop a theoretical model for Fourier domain mode-locked (FDML) lasers in a non-polarization-maintaining configuration, which is the most widely used type of FDML source. This theoretical approach is applied to analyze a widely wavelength-swept FDML setup, as used for picosecond pulse generation by temporal compression of the sweeps. We demonstrate that good agreement between simulation and experiment can only be obtained by including polarization effects due to fiber bending birefringence, polarization mode dispersion, and cross-phase modulation into the theoretical model. Notably, the polarization dynamics are shown to have a beneficial effect on the instantaneous linewidth, resulting in improved coherence and thus compressibility of the wavelength-swept FDML output.

  12. Domain Knowledge and Individual Interest: The Effects of Academic Level and Specialization in Statistics and Psychology

    ERIC Educational Resources Information Center

    Lawless, Kimberly A.; Kulikowich, Jonna M.

    2006-01-01

    Numerous research studies have highlighted the significant impact of domain knowledge and individual interest on learning. However, much of this prior research has neglected several important issues regarding the dynamic interplay of domain knowledge and individual interest both within and between domains as well as across developmental stages of…

  13. Effects of domain-specific exercise load on speed and accuracy of a domain-specific perceptual-cognitive task.

    PubMed

    Schapschröer, M; Baker, J; Schorer, J

    2016-08-01

    In the context of perceptual-cognitive expertise it is important to know whether physiological loads influence perceptual-cognitive performance. This study examined whether a handball specific physical exercise load influenced participants' speed and accuracy in a flicker task. At rest and during a specific interval exercise of 86.5-90% HRmax, 35 participants (experts: n=8, advanced: n=13, novices, n=14) performed a handball specific flicker task with two types of patterns (structured and unstructured). For reaction time, results revealed moderate effect sizes for group, with experts reacting faster than advanced and advanced reacting faster than novices, and for structure, with structured videos being performed faster than unstructured ones. A significant interaction for structure×group was also found, with experts and advanced players faster for structured videos, and novices faster for unstructured videos. For accuracy, significant main effects were found for structure with structured videos solved more accurately. A significant interaction for structure×group was revealed, with experts and advanced more accurate for structured scenes and novices more accurate for unstructured scenes. A significant interaction was also found for condition×structure; at rest, unstructured and structured scenes were performed with the same accuracy while under physical exercise, structured scenes were solved more accurately. No other interactions were found. These results were somewhat surprising given previous work in this area, although the impact of a specific physical exercise on a specific perceptual-cognitive task may be different from those tested generally.

  14. Size effect on quantum magnetic and thermo-magnetic oscillations in the non-spin domain phase

    NASA Astrophysics Data System (ADS)

    Bakaleinikov, L. A.; Gordon, A.

    2016-12-01

    Magnetic and thermo-magnetic (magneto-caloric) oscillations are studied in quantizing magnetic fields in slabs under conditions of the existence of non-spin (Condon) domains. Size effects on the magnetization oscillations in thin samples are calculated in the domain phase. Computations are carried out in the center of the period of the magnetization and temperature oscillations, taking into account the sample size. Phase diagrams, describing diamagnetic phase transitions and formation of Condon domains, are presented in finite size silver and quasi-two-dimensional organic conductors (2D) samples.

  15. Goldstone bosons as fractional cosmic neutrinos.

    PubMed

    Weinberg, Steven

    2013-06-14

    It is suggested that Goldstone bosons may be masquerading as fractional cosmic neutrinos, contributing about 0.39 to what is reported as the effective number of neutrino types in the era before recombination. The broken symmetry associated with these Goldstone bosons is further speculated to be the conservation of the particles of dark matter.

  16. The Cosmic Shoreline

    NASA Technical Reports Server (NTRS)

    Zahnle, Kevin J.; Catling, D. C.

    2013-01-01

    Volatile escape is the classic existential problem of planetary atmospheres. The problem has gained new currency now that we can study the cumulative effects of escape from extrasolar planets. Escape itself is likely to be a rapid process, relatively unlikely to be caught in the act, but the cumulative effects of escape in particular, the distinction between planets with and without atmospheres should show up in the statistics of the new planets. The new planets make a moving target. It can be difficult to keep up, and every day the paper boy brings more. Of course most of these will be giant planets loosely resembling Saturn or Neptune albeit hotter and nearer their stars, as big hot fast-orbiting exoplanets are the least exceedingly difficult to discover. But they are still planets, all in all, and although twenty years ago experts could prove on general principles that they did not exist, we have come round rather quickly, and they should be welcome now at LPSC. Here we will discuss the empirical division between planets with and without atmospheres. For most exoplanets the question of whether a planet has or has not an atmosphere is a fuzzy inference based on the planet's bulk density. A probably safe presumption is that a low density planet is one with abundant volatiles, in the general mold of Saturn or Neptune. On the other hand a high density low mass planet could be volatile-poor, in the general mold of Earth or Mercury. We will focus on planets, mostly seen in transit, for which both radius and mass are measured, as these are the planets with measured densities. More could be said: a lot of subtle recent work has been devoted to determining the composition of planets from equations of state or directly observing atmospheres in transit, but we will not go there. What interests us here is that, from the first, the transiting extrasolar planets appear to have fit into a pattern already seen in our own Solar System, as shown in Fig. 1. We first noticed this

  17. Expertise in ill-defined problem-solving domains as effective strategy use.

    PubMed

    Schunn, Christian D; McGregor, Mark U; Saner, Lelyn D

    2005-12-01

    Expertise consists of many different cognitive structures. Lemaire and Siegler (1995) have proposed a four-layered account of expertise from a strategies perspective: Experts have better strategies, tend to use strategies that are better overall more often, are better able to select the circumstances to which a strategy best applies, and are better able to execute a given strategy. Originally, this account came from work in simple, well-defined domains. We explored this account in the complex, ill-defined domain of platoon leadership. In Experiment 1A, we elicited free-text responses to leadership scenarios from novices, intermediates, and experts, finding expertise effects for strategy base rates and choice, but not for strategy existence or the number of strategies used. In Experiment 1B, we used a new group of experts to gather ratings of the execution accuracy of the responses in Experiment 1A and found expertise differences in the ability to execute the same strategies. We propose several elaborations to the original four-layered strategies account of expertise on the basis of these results.

  18. A Unified Frequency Domain Model to Study the Effect of Demyelination on Axonal Conduction

    PubMed Central

    Chaubey, Saurabh; Goodwin, Shikha J.

    2016-01-01

    Multiple sclerosis is a disease caused by demyelination of nerve fibers. In order to determine the loss of signal with the percentage of demyelination, we need to develop models that can simulate this effect. Existing time-based models does not provide a method to determine the influences of demyelination based on simulation results. Our goal is to develop a system identification approach to generate a transfer function in the frequency domain. The idea is to create a unified modeling approach for neural action potential propagation along the length of an axon containing number of Nodes of Ranvier (N). A system identification approach has been used to identify a transfer function of the classical Hodgkin–Huxley equations for membrane voltage potential. Using this approach, we model cable properties and signal propagation along the length of the axon with N node myelination. MATLAB/Simulink platform is used to analyze an N node-myelinated neuronal axon. The ability to transfer function in the frequency domain will help reduce effort and will give a much more realistic feel when compared to the classical time-based approach. Once a transfer function is identified, the conduction as a cascade of each linear time invariant system-based transfer function can be modeled. Using this approach, future studies can model the loss of myelin in various parts of nervous system. PMID:27103847

  19. A Unified Frequency Domain Model to Study the Effect of Demyelination on Axonal Conduction.

    PubMed

    Chaubey, Saurabh; Goodwin, Shikha J

    2016-01-01

    Multiple sclerosis is a disease caused by demyelination of nerve fibers. In order to determine the loss of signal with the percentage of demyelination, we need to develop models that can simulate this effect. Existing time-based models does not provide a method to determine the influences of demyelination based on simulation results. Our goal is to develop a system identification approach to generate a transfer function in the frequency domain. The idea is to create a unified modeling approach for neural action potential propagation along the length of an axon containing number of Nodes of Ranvier (N). A system identification approach has been used to identify a transfer function of the classical Hodgkin-Huxley equations for membrane voltage potential. Using this approach, we model cable properties and signal propagation along the length of the axon with N node myelination. MATLAB/Simulink platform is used to analyze an N node-myelinated neuronal axon. The ability to transfer function in the frequency domain will help reduce effort and will give a much more realistic feel when compared to the classical time-based approach. Once a transfer function is identified, the conduction as a cascade of each linear time invariant system-based transfer function can be modeled. Using this approach, future studies can model the loss of myelin in various parts of nervous system.

  20. Cosmic (Super)String Constraints from 21 cm Radiation

    SciTech Connect

    Khatri, Rishi; Wandelt, Benjamin D.

    2008-03-07

    We calculate the contribution of cosmic strings arising from a phase transition in the early Universe, or cosmic superstrings arising from brane inflation, to the cosmic 21 cm power spectrum at redshifts z{>=}30. Future experiments can exploit this effect to constrain the cosmic string tension G{mu} and probe virtually the entire brane inflation model space allowed by current observations. Although current experiments with a collecting area of {approx}1 km{sup 2} will not provide any useful constraints, future experiments with a collecting area of 10{sup 4}-10{sup 6} km{sup 2} covering the cleanest 10% of the sky can, in principle, constrain cosmic strings with tension G{mu} > or approx. 10{sup -10}-10{sup -12} (superstring/phase transition mass scale >10{sup 13} GeV)

  1. Effects of amino acid mutations in the pore-forming domain of the hemolytic lectin CEL-III.

    PubMed

    Nagao, Tomonao; Masaki, Risa; Unno, Hideaki; Goda, Shuichiro; Hatakeyama, Tomomitsu

    2016-10-01

    The hemolytic lectin CEL-III forms transmembrane pores in the membranes of target cells. A study on the effect of site-directed mutation at Lys405 in domain 3 of CEL-III indicated that replacements of this residue by relatively smaller residues lead to a marked increase in hemolytic activity, suggesting that moderately destabilizing domain 3 facilitates formation of transmembrane pores through conformational changes.

  2. Very similar spacing-effect patterns in very different learning/practice domains.

    PubMed

    Kornmeier, Jürgen; Spitzer, Manfred; Sosic-Vasic, Zrinka

    2014-01-01

    Temporally distributed ("spaced") learning can be twice as efficient as massed learning. This "spacing effect" occurs with a broad spectrum of learning materials, with humans of different ages, with non-human vertebrates and also invertebrates. This indicates, that very basic learning mechanisms are at work ("generality"). Although most studies so far focused on very narrow spacing interval ranges, there is some evidence for a non-monotonic behavior of this "spacing effect" ("nonlinearity") with optimal spacing intervals at different time scales. In the current study we focused both the nonlinearity aspect by using a broad range of spacing intervals and the generality aspect by using very different learning/practice domains: Participants learned German-Japanese word pairs and performed visual acuity tests. For each of six groups we used a different spacing interval between learning/practice units from 7 min to 24 h in logarithmic steps. Memory retention was studied in three consecutive final tests, one, seven and 28 days after the final learning unit. For both the vocabulary learning and visual acuity performance we found a highly significant effect of the factor spacing interval on the final test performance. In the 12 h-spacing-group about 85% of the learned words stayed in memory and nearly all of the visual acuity gain was preserved. In the 24 h-spacing-group, in contrast, only about 33% of the learned words were retained and the visual acuity gain dropped to zero. The very similar patterns of results from the two very different learning/practice domains point to similar underlying mechanisms. Further, our results indicate spacing in the range of 12 hours as optimal. A second peak may be around a spacing interval of 20 min but here the data are less clear. We discuss relations between our results and basic learning at the neuronal level.

  3. Cosmic structure formation

    NASA Technical Reports Server (NTRS)

    Bertschinger, Edumund

    1994-01-01

    This article reviews the prevailing paradigm for how galaxies and larger structures formed in the universe: gravitational instability. Basic observational facts are summarized to motivate the standard cosmological framework underlying most detailed investigations of structure formation. The observed univers approaches spatial uniformity on scales larger than about 10(exp 26) cm. On these scales gravitational dynamics is almost linear and therefore relatively easy to relate to observations of large-scale structure. On smaller scales cosmic structure is complicated not only by nonlinear gravitational clustering but also by nonlinear nongravitational gas dynamical processes. The complexity of these phenomena makes galaxy formation one of the grand challenge problems of the physical sciences. No fully satisfactory theory can presently account in detail for the observed cosmic structure. However, as this article summarizes, significant progress has been made during the last few years.

  4. 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 April 1994. Tables showing the current inventory of programs available from COSMIC are presented and program processing and evaluation activities are summarized. Five articles were prepared for publication in the NASA Tech Brief Journal. These articles (included in this report) describe the following software items: GAP 1.0 - Groove Analysis Program, Version 1.0; SUBTRANS - Subband/Transform MATLAB Functions for Image Processing; CSDM - COLD-SAT Dynamic Model; CASRE - Computer Aided Software Reliability Estimation; and XOPPS - OEL Project Planner/Scheduler Tool. Activities in the areas of marketing, customer service, benefits identification, maintenance and support, and disseminations are also described along with a budget summary.

  5. Cosmic Origin of Quantization

    NASA Astrophysics Data System (ADS)

    Calogero, Francesco

    An estimate is presented of the angular momentum associated with the stochastic cosmic tremor, which has been hypothesized to be caused by universal gravitation and by the granularity of matter, and to be itself the cause of quantization ("cosmic origin of quantization"). If that universal tremor has the spatial coherence which is instrumental in order that the estimated action associated with it have the order of magnitude of Planck's constant h, then the estimated order of magnitude of the angular momentum associated with it also has the same value. We moreover indicate how these findings (originally based on a simplified model of the Universe, as being made up only of particles having the nucleon mass) are affected (in fact, essentially unaffected) by the possible presence in the mass of the Universe of a large component made up of particles much lighter than nucleons ("dark", or "missing", mass).

  6. Note on cosmic censorship

    NASA Astrophysics Data System (ADS)

    Tipler, F. J.

    1985-05-01

    A number of recent theorems by Krolak (1983) and Newman (1983) purport to prove cosmic censorship by showing that strong-curvature singularities must be hidden behind horizons. It is shown that the 'null strong-curvature' condition which Newman imposes on certain classes of null geodesics to restrict curvature growth in the space-time does not hold in many physically realistic space-times: it is not satisfied by any null geodesic in the relevant class in any open Friedmann cosmological model, nor does it hold for any null geodesic in the relevant class in maximal Schwarzschild space. More generally it is argued that the singularity predicted by the Penrose singularity theorem is unlikely to be of the type eliminated by Newman. Thus the Newman theorems are probably without physical significance. The Krolak theorems, although based on a physically significant definition of strong curvature singularity, are mathematically invalid, and this approach cannot be used to obtain a cosmic-censorship theorem.

  7. Shielding against galactic cosmic rays

    NASA Technical Reports Server (NTRS)

    Schimmerling, W.; Wilson, J. W.; Nealy, J. E.; Thibeault, S. A.; Cucinotta, F. A.; Shinn, J. L.; Kim, M.; Kiefer, R.

    1996-01-01

    Ions of galactic origin are modified but not attenuated by the presence of shielding materials. Indeed, the number of particles and the absorbed energy behind most shield materials increases as a function of shield thickness. The modification of the galactic cosmic ray composition upon interaction with shielding is the only effective means of providing astronaut protection. This modification is intimately conntected with the shield transport porperties and is a strong function of shield composition. The systematic behavior of the shield properites in terms of microscopic energy absorption events will be discussed. The shield effectiveness is examined with respect to convectional protection practice and in terms of a biological endpoint: the efficiency for reduction of the probability of transformation of shielded C3H1OT1/2 mouse cells. The relative advantage of developing new shielding technologies is discussed in terms of a shield performance as related to biological effect and the resulting uncertainty in estimating astronaut risk.

  8. Galactic cosmic ray composition

    NASA Technical Reports Server (NTRS)

    Meyer, J. P.

    1986-01-01

    An assessment is given of the galactic cosmic ray source (GCRS) elemental composition and its correlation with first ionization potential. The isotopic composition of heavy nuclei; spallation cross sections; energy spectra of primary nuclei; electrons; positrons; local galactic reference abundances; comparison of solar energetic particles and solar coronal compositions; the hydrogen; lead; nitrogen; helium; and germanium deficiency problems; and the excess of elements are among the topics covered.

  9. Web life: Cosmic Diary

    NASA Astrophysics Data System (ADS)

    2009-03-01

    What is it? Cosmic Diary brings together a smorgasbord of blogging astronomers from around the world, with more than 50 contributors commenting on new discoveries and long-standing questions in astronomy - as well as offering insights into their ordinary working lives and outside interests. The site is sponsored by the International Astronomical Union and UNESCO, and it is one of 11 "cornerstone projects" of the International Year of Astronomy 2009 (IYA2009).

  10. Carl Sagan's Cosmic Connection

    NASA Astrophysics Data System (ADS)

    Sagan, Carl; Agel, Jerome

    2000-08-01

    Foreword Freeman Dyson; Personal reflections Ann Druyan; Preface; Part I. Cosmic Perspective: 1. A transitional animal; 2. The Unicorn of Cetus; 3. A message from earth; 4. A message to earth; 5. Experiments in utopias; 6. Chauvinism; 7. Space exploration as a human enterprise I. The scientific interest; 8. Space exploration as a human enterprise II. The public interest; 9. Space exploration as a human enterprise III. The historical interest; Part II. The Solar System: 10. On teaching the first grade; 11. 'The ancient and legendary Gods of old'; 12. The Venus detective story; 13. Venus is hell; 14. Science and 'intelligence'; 15. The moons of Barsoom; 16. The mountains of Mars I. Observations from earth; 17. The mountains of Mars II. Observations from space; 18. The canals of Mars; 19. The lost pictures of Mars; 20. The Ice Age and the cauldron; 21. Beginnings and ends of the Earth; 22. Terraforming the plants; 23. The exploration and utlization of the solar system; Part III. Beyond the Solar System: 24. Some of my best friends are dolphins; 25. 'Hello, central casting? Send me twenty extraterrestrials'; 26. The cosmic connection; 27. Extraterrestrial life: an idea whose time has come; 28. Has the Earth been visited?; 29. A search strategy for detecting extraterrestrial intelligence; 30. If we succeed 31. Cables, drums, and seashells; 32. The night freight to the stars; 33. Astroengineering; 34. Twenty questions: a classification of cosmic civilisations; 35. Galactic cultural exchanges; 36. A passage to elsewhere; 37. Starfolk I. A Fable; 38. Starfolk II. A future; 39. Starfolk III. The cosmic Cheshire cats; Epilog David Morrison; Index.

  11. Cosmic Rays in Thunderstorms

    NASA Astrophysics Data System (ADS)

    Buitink, Stijn; Scholten, Olaf; van den Berg, Ad; Ebert, Ute

    2013-04-01

    Cosmic Rays in Thunderstorms Cosmic rays are protons and heavier nuclei that constantly bombard the Earth's atmosphere with energies spanning a vast range from 109 to 1021 eV. At typical altitudes up to 10-20 km they initiate large particle cascades, called extensive air showers, that contain millions to billions of secondary particles depending on their initial energy. These particles include electrons, positrons, hadrons and muons, and are concentrated in a compact particle front that propagates at relativistic speed. In addition, the shower leaves behind a trail of lower energy electrons from ionization of air molecules. Under thunderstorm conditions these electrons contribute to the electrical and ionization processes in the cloud. When the local electric field is strong enough the secondary electrons can create relativistic electron run-away avalanches [1] or even non-relativistic avalanches. Cosmic rays could even trigger lightning inception. Conversely, strong electric fields also influence the development of the air shower [2]. Extensive air showers emit a short (tens of nanoseconds) radio pulse due to deflection of the shower particles in the Earth's magnetic field [3]. Antenna arrays, such as AERA, LOFAR and LOPES detect these pulses in a frequency window of roughly 10-100 MHz. These systems are also sensitive to the radiation from discharges associated to thunderstorms, and provide a means to study the interaction of cosmic ray air showers and the electrical processes in thunderstorms [4]. In this presentation we discuss the involved radiation mechanisms and present analyses of thunderstorm data from air shower arrays [1] A. Gurevich et al., Phys. Lett. A 165, 463 (1992) [2] S. Buitink et al., Astropart. Phys. 33, 1 (2010) [3] H. Falcke et al., Nature 435, 313 (2005) [4] S. Buitink et al., Astron. & Astrophys. 467, 385 (2007)

  12. A Warped Cosmic String

    SciTech Connect

    Slagter, R. J.

    2010-06-23

    We present a cosmic string solution in Einstein-Yang-Mills Gauss-Bonnet theory on a warped 5 dimensional space-time conform the Randall-Sundrum-2 theory. In a simplipied model, we find an exact solutions with exponential decreasing or periodic warp function. In a more general setting, where the metric- and Yang-Mills components depend on both scales and one of the YM components resides in the bulk, we find a time dependent numerical solution.

  13. Effect of treatment temperature on the microstructure of asphalt binders: insights on the development of dispersed domains.

    PubMed

    Menapace, I; Masad, E; Bhasin, A

    2016-04-01

    This paper offers important insights on the development of the microstructure in asphalt binders as a function of the treatment temperature. Different treatment temperatures are useful to understand how dispersed domains form when different driving energies for the mobility of molecular species are provided. Small and flat dispersed domains, with average diameter between 0.02 and 0.70 μm, were detected on the surface of two binders at room temperature, and these domains were observed to grow with an increase in treatment temperature (up to over 2 μm). Bee-like structures started to appear after treatment at or above 100°C. Moreover, the effect of the binder thickness on its microstructure at room temperature and at higher treatment temperatures was investigated and is discussed in this paper. At room temperature, the average size of the dispersed domains increased as the binder thickness decreased. A hypothesis that conciliates current theories on the origin and development of dispersed domains is proposed. Small dispersed domains (average diameter around 0.02 μm) are present in the bulk of the binder, whereas larger domains and bee-like structures develop on the surface, following heat treatment or mechanical disturbance that reduces the film thickness. Molecular mobility and association are the key factors in the development of binder microstructure.

  14. The cosmic background explorer

    SciTech Connect

    Gulkis, G. ); Lubin, P.M. ); Meyer, S.S. ); Silverberg, R.F.

    1990-01-01

    Late last year the National Aeronautics and Space Administration launched its first satellite dedicated to the study of phenomena related to the origins of the universe. The satellite, called the Cosmic Background Explorer (COBE), carries three complementary detectors that will make fundamental measurements of the celestial radiation. Part of that radiation is believed to have originated in processes that occurred at the very dawn of the universe. By measuring the remnant radiation at wavelengths from one micrometer to one centimeter across the entire sky, scientists hope to be able to solve many mysteries regarding the origin and evolution of the early universe. Unfortunately, these radiative relics of the early universe are weak and veiled by local astrophysical and terrestrial sources of radiation. The wavelengths of the various cosmic components may also overlap, thereby making the understanding of the diffuse celestial radiation a challenge. Nevertheless, the COBE instruments, with their full-sky coverage, high sensitivity to a wide range of wavelengths and freedom from interference from the earth's atmosphere, will constitute for astrophysicists an observatory of unprecedented sensitivity and scope. The interesting cosmic signals will then be separated from one another and from noncosmic radiation sources by a comprehensive analysis of the data.

  15. The effects of cholesterol concentration in lipid packing and domain registration in ternary mixture lipid multilayer

    NASA Astrophysics Data System (ADS)

    Ma, Yicong; Ghosh, Sajal; Connelly, Laura; Lal, Ratneshwar; Sinha, Sunil

    2013-03-01

    The effects of cholesterol in membrane rafts formation remain a mystery even until today. In our study of model membrane multilayer systems consisting of DPPC/DOPC/Cholesterol, we have characterized the morphology changes using AFM and optical microscopy, and the bilayer electron density profile using X-ray reflectivity, as a function of cholesterol concentration. In this presentation, we shall discuss how the cholesterol concentration affects the lipid packing within the bilayer, as well as the interlayer coupling of phase separated domains. X-ray scattering, AFM and optical microscopy which look at different length scales would constitute a complete picture. Our results may shed new light on the understanding of the role of cholesterol in raft formation in biological membranes. This work is supported by a grant from the Biomolecular Materials Program, Division of Materials Science and Engineering, Basic Energy Sciences, US Department of Energy under Award no. DE-FG02-04ER46173.

  16. Mutual effects of disorder and order in fusion proteins between intrinsically disordered domains and fluorescent proteins.

    PubMed

    Lotti, Marina; Longhi, Sonia

    2012-01-01

    Intrinsically disordered proteins are being paid an increasing amount of interest due to the understanding of the crucial role that flexible regions play in molecular recognition and in signaling. Accordingly, reports focusing on the structural and functional characterization of intrinsically disordered proteins or regions are growing exponentially. Relatively few studies have however been reported on the mutual effects of ordered and disordered moieties in artificial fusion proteins. In this review, we focus on the few available experimental data based on the use of chimeras in which fluorescent proteins were fused to disordered domains of different lengths, compactness and propensity to form secondary structures. The impact of the artificial fusion on the conformational and functional properties of the resulting proteins is discussed.

  17. Effect of substrate rotation on domain structure and magnetic relaxation in magnetic antidot lattice arrays

    SciTech Connect

    Mallick, Sougata; Mallik, Srijani; Bedanta, Subhankar

    2015-08-28

    Microdimensional triangular magnetic antidot lattice arrays were prepared by varying the speed of substrate rotation. The pre-deposition patterning has been performed using photolithography technique followed by a post-deposition lift-off. Surface morphology taken by atomic force microscopy depicted that the growth mechanism of the grains changes from chain like formation to island structures due to the substrate rotation. Study of magnetization reversal via magneto optic Kerr effect based microscopy revealed reduction of uniaxial anisotropy and increase in domain size with substrate rotation. The relaxation measured under constant magnetic field becomes faster with rotation of the substrate during deposition. The nature of relaxation for the non-rotating sample can be described by a double exponential decay. However, the relaxation for the sample with substrate rotation is well described either by a double exponential or a Fatuzzo-Labrune like single exponential decay, which increases in applied field.

  18. Optical imaging through dynamic turbid media using the Fourier-domain shower-curtain effect.

    PubMed

    Edrei, Eitan; Scarcelli, Giuliano

    2016-01-20

    Several phenomena have been recently exploited to circumvent scattering and have succeeded in imaging or focusing light through turbid layers. However, the requirement for the turbid medium to be steady during the imaging process remains a fundamental limitation of these methods. Here we introduce an optical imaging modality that overcomes this challenge by taking advantage of the so-called shower-curtain effect, adapted to the spatial-frequency domain via speckle correlography. We present high resolution imaging of objects hidden behind millimeter-thick tissue or dense lens cataracts. We demonstrate our imaging technique to be insensitive to rapid medium movements (> 5 m/s) beyond any biologically-relevant motion. Furthermore, we show this method can be extended to several contrast mechanisms and imaging configurations.

  19. Optical imaging through dynamic turbid media using the Fourier-domain shower-curtain effect

    PubMed Central

    Edrei, Eitan; Scarcelli, Giuliano

    2016-01-01

    Several phenomena have been recently exploited to circumvent scattering and have succeeded in imaging or focusing light through turbid layers. However, the requirement for the turbid medium to be steady during the imaging process remains a fundamental limitation of these methods. Here we introduce an optical imaging modality that overcomes this challenge by taking advantage of the so-called shower-curtain effect, adapted to the spatial-frequency domain via speckle correlography. We present high resolution imaging of objects hidden behind millimeter-thick tissue or dense lens cataracts. We demonstrate our imaging technique to be insensitive to rapid medium movements (> 5 m/s) beyond any biologically-relevant motion. Furthermore, we show this method can be extended to several contrast mechanisms and imaging configurations. PMID:27347498

  20. Effect of noise on modulation amplitude and phase in frequency-domain diffusive imaging

    PubMed Central

    Kupinski, Matthew A.

    2012-01-01

    Abstract. We theoretically investigate the effect of noise on frequency-domain heterodyne and/or homodyne measurements of intensity-modulated beams propagating through diffusive media, such as a photon density wave. We assumed that the attenuated amplitude and delayed phase are estimated by taking the Fourier transform of the noisy, modulated output data. We show that the estimated amplitude and phase are biased when the number of output photons is small. We also show that the use of image intensifiers for photon amplification in heterodyne or homodyne measurements increases the amount of biases. Especially, it turns out that the biased estimation is independent of AC-dependent noise in sinusoidal heterodyne or homodyne outputs. Finally, the developed theory indicates that the previously known variance model of modulation amplitude and phase is not valid in low light situations. Monte-Carlo simulations with varied numbers of input photons verify our theoretical trends of the bias. PMID:22352660

  1. Cosmic rays and space weather

    NASA Astrophysics Data System (ADS)

    Dorman, L. I.

    2003-04-01

    It is well known that in periods of great FEP (Flare Energetic Particle), fluxes can be so big that memory of computers and other electronics in space may be destroyed, satellites and spacecrafts became dead (each year insurance companies paid more than 500,000,000 dollars for these failures). In these periods is necessary to switch off some part of electronics for short time to protect computer memories. These periods are also dangerous for astronauts on space-ships, and passengers and crew in commercial jets (especially during S5 radiation storms according to classification of NOAA). The problem is how to forecast exactly these dangerous phenomena. We show that exact forecast can be made by using high-energy particles (about 5-10 GeV/nucleon and higher) which transportation from the Sun is characterized by much bigger diffusion coefficient than for small and middle energy particles. Therefore high energy particles came from the Sun much more early (8-20 minutes after acceleration and escaping into solar wind) than main part of smaller energy particles caused dangerous situation for electronics and people health (about 30-60 minutes later). We describe here principles and experience of automatically working programs "FEP-Search-1 min", "FEP-Search-2 min","FEP-Search-5 min", developed and checked in the Emilio Segre' Observatory of Israel Cosmic Ray Center (2025 m above sea level, cut-off rigidity 10.8 GV). The second step is automatically determination of flare energetic particle spectrum, and then automatically determination of diffusion coefficient in the interplanetary space, time of ejection and energy spectrum of FEP in source; forecasting of expected FEP flux and radiation hazard for space-probes in space, satellites in the magnetosphere, jets and various objects in the atmosphere and on the ground. We will describe also the theory and experience of high energy cosmic ray using for forecasting of major geomagnetic storms accompanied by Forbush-effects (what

  2. SMALL-SCALE ANISOTROPIES OF COSMIC RAYS FROM RELATIVE DIFFUSION

    SciTech Connect

    Ahlers, Markus; Mertsch, Philipp

    2015-12-10

    The arrival directions of multi-TeV cosmic rays show significant anisotropies at small angular scales. It has been argued that this small-scale structure can naturally arise from cosmic ray scattering in local turbulent magnetic fields that distort a global dipole anisotropy set by diffusion. We study this effect in terms of the power spectrum of cosmic ray arrival directions and show that the strength of small-scale anisotropies is related to properties of relative diffusion. We provide a formalism for how these power spectra can be inferred from simulations and motivate a simple analytic extension of the ensemble-averaged diffusion equation that can account for the effect.

  3. A meta-analysis of the effectiveness of crew resource management training in acute care domains.

    PubMed

    O'Dea, Angela; O'Connor, Paul; Keogh, Ivan

    2014-12-01

    The healthcare industry has seen an increase in the adoption of team training, such as crew resource management (CRM), to improve teamwork and coordination within acute care medical teams. A meta-analysis was carried out in order to quantify the effects of CRM training on reactions, learning, behaviour and clinical care outcomes. Biases in the research evidence are identified and recommendations for training development and evaluation are presented. PUBMED, EMBASE and PsychInfo were systematically searched for all relevant papers. Peer reviewed papers published in English between January 1985 and September 2013, which present empirically based studies focusing on interventions to improve team effectiveness in acute health care domains, were included. A total of 20 CRM-type team training evaluation studies were found to fulfil the a priori criteria for inclusion in the meta-analysis. Overall, CRM trained participants responded positively to CRM (mean score 4.25 out of a maximum of 5), the training had large effects on participants' knowledge (d=1.05), a small effect on attitudes (d=0.22) and a large effect on behaviours (d=1.25). There was insufficient evidence to support an effect on clinical care outcomes or long term impacts. The findings support the premise that CRM training can positively impact teamwork in healthcare and provide estimates of the expected effects of training. However, there is a need for greater precision in outcome assessment, improved standardisation of methods and measures, and more robust research design. Stronger evidence of effectiveness will require multi-level, multicentre, multispecialty and longitudinal studies.

  4. The Antitumor Effect of Single-domain Antibodies Directed Towards Membrane-associated Catalase and Superoxide Dismutase.

    PubMed

    Bauer, Georg; Motz, Manfred

    2016-11-01

    Neutralizing single-domain antibodies directed towards catalase or superoxide dismutase (SOD) caused efficient reactivation of intercellular reactive oxygen species/reactive nitrogen species (ROS/RNS)-dependent apoptosis-inducing signaling specifically in human tumor cells. Single-domain antibodies targeted tumor cell-specific membrane-associated SOD and catalase, but not the corresponding intracellular enzymes. They were shown to be about 200-fold more effective than corresponding classical recombinant antigen-binding fragments and more than four log steps more efficient than monoclonal antibodies. Combined addition of single-domain antibodies against catalase and SOD caused a remarkable synergistic effect. Proof-of-concept experiments in immunocompromised mice using human tumor xenografts and single-domain antibodies directed towards SOD showed an inhibition of tumor growth. Neutralizing single-domain antibodies directed to catalase and SOD also caused a very strong synergistic effect with the established chemotherapeutic agent taxol, indicating an overlap of signaling pathways. This effect might also be useful in order to avoid unwanted side-effects and to drastically lower the costs for taxol-based therapy.

  5. Non-local effects in dual-probe-sideband Brillouin optical time domain analysis.

    PubMed

    Dominguez-Lopez, Alejandro; Angulo-Vinuesa, Xabier; Lopez-Gil, Alexia; Martin-Lopez, Sonia; Gonzalez-Herraez, Miguel

    2015-04-20

    According to recent models, non-local effects in dual-probe-sideband Brillouin Optical Time Domain Analysis (BOTDA) systems should be essentially negligible whenever the probe power is below the Stimulated Brillouin Scattering (SBS) threshold. This paper shows that actually there appear non-local effects in this type of systems before the SBS threshold. To explain these effects it is necessary to take into account a full spectral description of the SBS process. The pump pulse experiences a frequency-dependent spectral deformation that affects the readout process differently in the gain and loss configurations. This paper provides a simple analytical model of this phenomenon, which is validated against compelling experimental data, showing good agreement. The main conclusion of our study is that the measurements in gain configuration are more robust to this non-local effect than the loss configuration. Experimental and theoretical results show that, for a total probe wave power of ~1 mW (500 μW on each sideband), there is an up-shifting of ~1 MHz in the Brillouin Frequency Shift (BFS) retrieved from the Brillouin Loss Spectrum, whereas the BFS extracted from the measured Brillouin Gain Spectrum is up-shifted only ~0.6 MHz. These results are of particular interest for manufacturers of long-range BOTDA systems.

  6. Differential effects of amino-terminal distal and proximal domains in the regulation of human erg K(+) channel gating.

    PubMed Central

    Viloria, C G; Barros, F; Giráldez, T; Gómez-Varela, D; de la Peña, P

    2000-01-01

    The participation of amino-terminal domains in human ether-a-go-go (eag)-related gene (HERG) K(+) channel gating was studied using deleted channel variants expressed in Xenopus oocytes. Selective deletion of the HERG-specific sequence (HERG Delta138-373) located between the conserved initial amino terminus (the eag or PAS domain) and the first transmembrane helix accelerates channel activation and shifts its voltage dependence to hyperpolarized values. However, deactivation time constants from fully activated states and channel inactivation remain almost unaltered after the deletion. The deletion effects are equally manifested in channel variants lacking inactivation. The characteristics of constructs lacking only about half of the HERG-specific domain (Delta223-373) or a short stretch of 19 residues (Delta355-373) suggest that the role of this domain is not related exclusively to its length, but also to the presence of specific sequences near the channel core. Deletion-induced effects are partially reversed by the additional elimination of the eag domain. Thus the particular combination of HERG-specific and eag domains determines two important HERG features: the slow activation essential for neuronal spike-frequency adaptation and maintenance of the cardiac action potential plateau, and the slow deactivation contributing to HERG inward rectification. PMID:10866950

  7. Effect of the growth conditions on the anisotropy, domain structures and the relaxation in Co thin films

    NASA Astrophysics Data System (ADS)

    Mallik, Srijani; Mallick, Sougata; Bedanta, Subhankar

    2017-04-01

    We report a systematic study on the anisotropy symmetry, magnetic domains and magnetic relaxation behavior in Co thin films deposited on MgO (001) substrate by varying (i) the pre-annealing condition and (ii) the speed of substrate rotation during deposition. Substrate annealing prior to deposition leads to the formation of textured thin films. On contrary Co films prepared without substrate pre-annealing exhibit polycrystalline nature. Surface topography imaged by atomic force microscopy (AFM) depicts a profound effect of growth condition on grain size and its distribution. Magnetic hysteresis measurement along with simultaneous domain imaging has been performed by magneto optic Kerr effect (MOKE) based microscope by varying the angle (ϕ) between the easy axis and the direction of applied magnetic field. We observed the existence of cubic and uniaxial anisotropy due to the presence of substrate annealing and oblique angular deposition, respectively. Along the easy axis, magnetization reversal is governed by 180° domain wall motion via branched domains. However, for easy axis<ϕdomains appear in addition to branched domains during the reversal process. We observed that the magnetic relaxation behavior under constant magnetic field strongly depends on the size and distribution of the grains.

  8. The Origin of Cosmic Rays

    ScienceCinema

    Blasi, Pasquale [INAF/Arcetri-Italy and Fermilab, Italy

    2016-07-12

    Cosmic Rays reach the Earth from space with energies of up to more than 1020 eV, carrying information on the most powerful particle accelerators that Nature has been able to assemble. Understanding where and how cosmic rays originate has required almost one century of investigations, and, although the last word is not written yet, recent observations and theory seem now to fit together to provide us with a global picture of the origin of cosmic rays of unprecedented clarity. Here we will describe what we learned from recent observations of astrophysical sources (such as supernova remnants and active galaxies) and we will illustrate what these observations tell us about the physics of particle acceleration and transport. We will also discuss the “end” of the Galactic cosmic ray spectrum, which bridges out attention towards the so called ultra high energy cosmic rays (UHECRs). At ~1020 eV the gyration scale of cosmic rays in cosmic magnetic fields becomes large enough to allow us to point back to their sources, thereby allowing us to perform “cosmic ray astronomy”, as confirmed by the recent results obtained with the Pierre Auger Observatory. We will discuss the implications of these observations for the understanding of UHECRs, as well as some questions which will likely remain unanswered and will be the target of the next generation of cosmic ray experiments.

  9. The N-Terminal Domain of the E. coli PriA Helicase Contains Both the DNA- and the Nucleotide-Binding Sites. Energetics of Domain-DNA Interactions and Allosteric Effect of the Nucleotide Cofactors§

    PubMed Central

    Szymanski, Michal R.; Bujalowski, Paul J.; Jezewska, Maria J.; Gmyrek, Aleksandra M.; Bujalowski, Wlodzimierz

    2011-01-01

    Functional interactions of the E. coli PriA helicase 181N-terminal domain with the DNA and nucleotide cofactors have been quantitatively examined. The isolated 181N-terminal domain forms a stable dimer in solution, most probably reflecting the involvement of the domain in specific cooperative interactions of the intact PriA protein - dsDNA complex. Only one monomer of the domain dimer binds the DNA, i.e., the dimer has one effective DNA-binding site. Although the total site-size of the dimer - ssDNA complex is ~13 nucleotides, the DNA-binding subsite engages in direct interactions ~5 nucleotides. A small number of interacting nucleotides indicates that the DNA-binding subsites of the PriA helicase, i.e., the strong subsite on the helicase domain and the weak subsite on the N-terminal domain, are spatially separated in the intact enzyme. Contrary to current views, the subsite has only a slight preference for the 3′-end OH group of the ssDNA and lacks any significant base specificity, although it has a significant dsDNA affinity. Unlike the intact helicase, the DNA-binding subsite of the isolated domain is in an open conformation, indicating the presence of the direct helicase domain - N-terminal domain interactions. The discovery that the 181N-terminal domain possesses a nucleotide-binding site places the allosteric, weak nucleotide-binding site of the intact PriA on the N-terminal domain. The specific ADP effect on the domain DNA-binding subsite indicates that in the intact helicase, the bound ADP not only opens the DNA-binding subsite but also increases its intrinsic DNA affinity. PMID:21888358

  10. A Job with a Future? Delay Discounting, Magnitude Effects, and Domain Independence of Utility for Career Decisions.

    ERIC Educational Resources Information Center

    Schoenfelder, Thomas E.; Hantula, Donald A.

    2003-01-01

    Seniors (n=20) assessed two job offers with differences in domain (salary/tasks), delay (career-long earnings), and magnitude (initial salary offer). Contrary to discounted utility theory, choices reflected nonconstant discount rates for future salary/tasks (delay effect), lower discount rates for salary/preferred tasks (magnitude effect), and a…

  11. Adaptation effects to attractiveness of face photographs and art portraits are domain-specific.

    PubMed

    Hayn-Leichsenring, Gregor U; Kloth, Nadine; Schweinberger, Stefan R; Redies, Christoph

    2013-01-01

    We studied the neural coding of facial attractiveness by investigating effects of adaptation to attractive and unattractive human faces on the perceived attractiveness of veridical human face pictures (Experiment 1) and art portraits (Experiment 2). Experiment 1 revealed a clear pattern of contrastive aftereffects. Relative to a pre-adaptation baseline, the perceived attractiveness of faces was increased after adaptation to unattractive faces, and was decreased after adaptation to attractive faces. Experiment 2 revealed similar aftereffects when art portraits rather than face photographs were used as adaptors and test stimuli, suggesting that effects of adaptation to attractiveness are not restricted to facial photographs. Additionally, we found similar aftereffects in art portraits for beauty, another aesthetic feature that, unlike attractiveness, relates to the properties of the image (rather than to the face displayed). Importantly, Experiment 3 showed that aftereffects were abolished when adaptors were art portraits and face photographs were test stimuli. These results suggest that adaptation to facial attractiveness elicits aftereffects in the perception of subsequently presented faces, for both face photographs and art portraits, and that these effects do not cross image domains.

  12. The Effects of the Ionosphere on Ground-based Detection of the Global 21 cm Signal from the Cosmic Dawn and the Dark Ages

    NASA Astrophysics Data System (ADS)

    Datta, Abhirup; Bradley, Richard; Burns, Jack O.; Harker, Geraint; Komjathy, Attila; Lazio, T. Joseph W.

    2016-11-01

    Detection of the global H i 21 cm signal from the Cosmic Dawn and the Epoch of Reionization is the key science driver for several ongoing ground-based and future ground-/space-based experiments. The crucial spectral features in the global 21 cm signal (turning points) occur at low radio frequencies ≲ 100 {{MHz}}. In addition to the human-generated radio frequency interference, Earth’s ionosphere drastically corrupts low-frequency radio observations from the ground. In this paper, we examine the effects of time-varying ionospheric refraction, absorption, and thermal emission at these low radio frequencies and their combined effect on any ground-based global 21 cm experiment. It should be noted that this is the first study of the effect of a dynamic ionosphere on global 21 cm experiments. The fluctuations in the ionosphere are influenced by solar activity with flicker noise characteristics. The same characteristics are reflected in the ionospheric corruption to any radio signal passing through the ionosphere. As a result, any ground-based observations of the faint global 21 cm signal are corrupted by flicker noise (or 1/f noise, where f is the dynamical frequency) which scales as {ν }-2 (where ν is the frequency of radio observation) in the presence of a bright galactic foreground (\\propto {ν }-s, where s is the radio spectral index). Hence, the calibration of the ionosphere for any such experiment is critical. Any attempt to calibrate the ionospheric effects will be subject to the inaccuracies in the current ionospheric measurements using Global Positioning System (GPS) ionospheric measurements, riometer measurements, ionospheric soundings, etc. Even considering an optimistic improvement in the accuracy of GPS-total electron content measurements, we conclude that Earth’s ionosphere poses a significant challenge in the absolute detection of the global 21 cm signal below 100 MHz.

  13. The Effect Direction Plot: Visual Display of Non-Standardised Effects across Multiple Outcome Domains

    ERIC Educational Resources Information Center

    Thomson, Hilary J.; Thomas, Sian

    2013-01-01

    Visual display of reported impacts is a valuable aid to both reviewers and readers of systematic reviews. Forest plots are routinely prepared to report standardised effect sizes, but where standardised effect sizes are not available for all included studies a forest plot may misrepresent the available evidence. Tabulated data summaries to…

  14. International Cosmic Ray Conference, 13th, University of Denver, Denver, Colo., August 17-30, 1973, Proceedings. Volume 5

    NASA Technical Reports Server (NTRS)

    1974-01-01

    An X-ray observation of the Norma-Lupus region, charge and isotope measurements of heavy cosmic ray nuclei and their role in the determination of cosmic ray age, and the possibility of a contribution to primary cosmic ray spectra from pulsars are among the topics covered in papers concerned with some of the results of recent cosmic ray research. Other topics covered include multiple scattering of charged particles in magnetic fields, absorption of primary cosmic rays in the atmosphere, and phase lag effects on cosmic ray modulation during a recent solar cycle. Individual items are announced in this issue.

  15. Cosmic ray hazards in the solar system.

    NASA Technical Reports Server (NTRS)

    Milford, S. N.

    1965-01-01

    Cosmic ray hazards in solar system considered from measurements of cosmic ray energy and charge spectra near Earth and in interplanetary space near Earth, together with interaction of cosmic rays with Moon surface

  16. On Becoming a Cosmic Educator. Spotlight: Cosmic Education.

    ERIC Educational Resources Information Center

    Maier, Biff

    2002-01-01

    Discusses Maria Montessori's five pedagogical guidelines for her Cosmic Education concept: starting with the larger context; treating planet Earth as a cosmic organism; stressing similarities among seemingly different groups of people, organisms, or objects; showing chains of interdependence among all things; and examining behavior from a cosmic…

  17. Domain wall dynamics and Hall effect in eddy current loop in amorphous ferromagnetic wire with small helical anisotropy

    NASA Astrophysics Data System (ADS)

    Ziman, J.; Onufer, J.; Kladivová, M.

    2011-10-01

    Small helical anisotropy was induced in amorphous ferromagnetic Co 68.2Fe 4.3Si 12.5B 15 wire by current annealing and simultaneous application of tensile stress and torsion. Presence of helical anisotropy was confirmed by measurement and analysis of the circular magnetic flux versus axial magnetic field hysteresis loops. These measurements also showed that a single domain wall between circular domains can be created by placing the wire in a sufficiently high inhomogeneous magnetic field generated by Helmholtz coils with opposite currents. The domain wall velocity versus axial driving field was measured. The results show that the basic dynamic properties (magnitude of the wall mobility, field interval in which linear dependencies between velocity and field are observed, accelerated increase of the velocity for higher fields) are very similar to those obtained for the domain wall between circular domains driven by a constant circular field. The Hall effect was detected in the eddy current loop generated by the moving domain wall.

  18. The influence of the electrical boundary condition on domain structures and electrocaloric effect of PbTiO3 nanostructures

    NASA Astrophysics Data System (ADS)

    Chen, Z. Y.; Su, Y. X.; Zhou, Z. D.; Lei, L. S.; Yang, C. P.

    2016-05-01

    The electrocaloric effect (ECE) induced by the domain switching of PbTiO3 (PTO) nanoparticles under the different electrical boundary conditions is carried out using the phase field model. The toroidal moment of polarization with vortex domain structures decreases to zero taking surface charge compensation into the electrical boundary condition, i.e. intermediate electrical boundary. There exists a critical parameter value 0.25, which decides the single domain and vortex domain structures of ferroelectric nanomaterial at the room temperature. The loops of toroidal moment as a function of the applied curled electric filed are obtained under the different electrical boundary conditions. The various domain structures in ferroelectric nanostructure are discussed in detail. Moreover negative and positive adiabatic temperature changes accompanying with vortex domain structure switching are obtained with the curled electric field under the intermediate electrical boundary. These results indicate that ferroelectric nanostructures can be practical used in field of cooling and heating technology through adjusting the surface electrical boundary.

  19. Cosmic Ray Transport in the Distant Heliosheath

    NASA Technical Reports Server (NTRS)

    Florinski, V.; Adams, James H.; Washimi, H.

    2011-01-01

    The character of energetic particle transport in the distant heliosheath and especially in the vicinity of the heliopause could be quite distinct from the other regions of the heliosphere. The magnetic field structure is dominated by a tightly wrapped oscillating heliospheric current sheet which is transported to higher latitudes by the nonradial heliosheath flows. Both Voyagers have, or are expected to enter a region dominated by the sectored field formed during the preceding solar maximum. As the plasma flow slows down on approach to the heliopause, the distance between the folds of the current sheet decreases to the point where it becomes comparable to the cyclotron radius of an energetic ion, such as a galactic cosmic ray. Then, a charged particle can effectively drift across a stack of magnetic sectors with a speed comparable with the particle s velocity. Cosmic rays should also be able to efficiently diffuse across the mean magnetic field if the distance between sector boundaries varies. The region of the heliopause could thus be much more permeable to cosmic rays than was previously thought. This new transport proposed mechanism could explain the very high intensities (approaching the model interstellar values) of galactic cosmic rays measured by Voyager 1 during 2010-2011.

  20. Computer-forgetfulness, cosmic radiation and an ion-microscope

    NASA Astrophysics Data System (ADS)

    Fischer, B.; Barak, J.; Adler, E.; Metzger, S.

    1998-12-01

    After an introduction to the cosmic ray environment, we show why few-MeV heavy ions are suitable to simulate cosmic radiation effects in integrated circuits, and how the sensitive sites for various radiation effects can be localised using an ion microscope and a specially designed, small hardware circuit. As a tutorial for the potential of the microprobe technique we show a series of results obtained for a 2k × 8 bit static RAM (HM65162).

  1. 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.

  2. Deconvoluting the Effect of the Hydrophobic and Hydrophilic Domains of an Amphiphilic Integral Membrane Protein in Lipid Bicontinuous Cubic Mesophases.

    PubMed

    van 't Hag, Leonie; Shen, Hsin-Hui; Lu, Jingxiong; Hawley, Adrian M; Gras, Sally L; Drummond, Calum J; Conn, Charlotte E

    2015-11-10

    Lipidic bicontinuous cubic mesophases with encapsulated amphiphilic proteins are widely used in a range of biological and biomedical applications, including in meso crystallization, as drug delivery vehicles for therapeutic proteins, and as biosensors and biofuel cells. However, the effect of amphiphilic protein encapsulation on the cubic phase nanostructure is not well-understood. In this study, we illustrate the effect of incorporating the bacterial amphiphilic membrane protein Ag43, and its individual hydrophobic β(43) and hydrophilic α(43) domains, in bicontinuous cubic mesophases. For the monoolein, monoalmitolein, and phytantriol cubic phases with and without 8% w/w cholesterol, the effect of the full length amphiphilic protein Ag43 on the cubic phase nanostructure was more significant than the sum of the individual hydrophobic β(43) and hydrophilic α(43) domains. Several factors were found to potentially influence the impact of the hydrophobic β(43) domain on the cubic phase internal nanostructure. These include the size of the hydrophobic β(43) domain relative to the thickness of the lipid bilayer, as well as its charge and diameter. The size of the hydrophilic α(43) domain relative to the water channel radius of the cubic mesophase was also found to be important. The secondary structure of the Ag43 proteins was affected by the hydrophobic thickness and physicochemical properties of the lipid bilayer and the water channel diameter of the cubic phase. Such structural changes may be small but could potentially affect membrane protein function.

  3. Cosmic Background Radiation

    NASA Astrophysics Data System (ADS)

    Sidharth, B. G.; Valluri, S. R.

    2015-08-01

    It is shown that a collection of photons with nearly the same frequency exhibits a "condensation" type of phenomenon corresponding to a peak intensity. The observed cosmic background radiation can be explained from this standpoint. We have obtained analogous results by extremization of the occupation number for photons with the use of the Lambert W function. Some of the interesting applications of this function are briefly discussed in the context of graphene which exhibits an interesting two dimensional structure with several characteristic properties and diverse practical applications.

  4. Antiprotons in cosmic rays

    NASA Technical Reports Server (NTRS)

    Balasubrahmanyan, V. K.; Ormes, J. F.; Streitmatter, R. E.

    1987-01-01

    Recent experimental observations and results are discussed. It was found that the approximately 50 antiprotons collected in balloon experiments to date have generated considerable theoretical interest. Clearly, confirmatory experiments and measurements over an extended energy range are required before definite conclusions are drawn. Antiproton measurements have a bearing on astrophysical problems ranging from cosmic ray propagation to issues of cosmological import. The next generation of balloon experiments and the Particle Astrophysics Magnet Facility being discussed for operation on NASA's space station should provide data and insights of highest interest.

  5. Wormhole cosmic censorship

    NASA Astrophysics Data System (ADS)

    Matos, Tonatiuh; Ureña-López, L. Arturo; Miranda, Galaxia

    2016-05-01

    We analyze the properties of a Kerr-like wormhole supported by phantom matter, which is an exact solution of the Einstein-phantom field equations. It is shown that the solution has a naked ring singularity which is unreachable to null geodesics falling freely from the outside. Similarly to Roger Penrose's cosmic censorship, that states that all naked singularities in the Universe must be protected by event horizons, here we conjecture from our results that a naked singularity can also be fully protected by the intrinsic properties of a wormhole's throat.

  6. The Cosmic Background Explorer

    NASA Technical Reports Server (NTRS)

    Gulkis, Samuel; Lubin, Philip M.; Meyer, Stephan S.; Silverberg, Robert F.

    1990-01-01

    The Cosmic Background Explorer (CBE), NASA's cosmological satellite which will observe a radiative relic of the big bang, is discussed. The major questions connected to the big bang theory which may be clarified using the CBE are reviewed. The satellite instruments and experiments are described, including the Differential Microwave Radiometer, which measures the difference between microwave radiation emitted from two points on the sky, the Far-Infrared Absolute Spectrophotometer, which compares the spectrum of radiation from the sky at wavelengths from 100 microns to one cm with that from an internal blackbody, and the Diffuse Infrared Background Experiment, which searches for the radiation from the earliest generation of stars.

  7. Domain-size effects in optical diffraction from polymer/composite microparticles

    SciTech Connect

    Ford, J.V.; Sumpter, B.G.; Noid, D.W.; Barnes, M.D.; Hill, S.C.; Hillis, D.B.

    2000-01-27

    Poly(ethylene glycol) [PEG] microparticles were doped with ceramic or latex nanoparticles in order to examine domain-size and refractive index effects of nanometer-sized guest inclusions on two-dimensional diffraction patterns. Composite microparticles were examined for different inclusion sizes and polymer/nanoparticle weight ratios in order to determine the size and number-density threshold of detection for guest nanoparticles within the polymer host as indicated by fringe distortion in 2-D angular scattering. PEG host particles having a 10 {micro}m (nominal) diameter were formed with three different guest nanoparticles (Al{sub 2}O{sub 3}, TiO{sub 2}, and latex nanospheres with respective sizes of 46, 29, and 14 nm). For the ceramic nanoparticle inclusions, distortion was observed at relative guest-host weight fractions of 5--10%. For the 14 nm latex inclusions, no distortion was observed at any weight fraction. A perturbation method was used to simulate the effect of nanometer-size inclusions on 2-D optical diffraction from polymer host microparticles and to suggest how the distortions should vary with inclusion size, refractive index, and number.

  8. Solar modulation of cosmic rays observed by PAMELA

    NASA Astrophysics Data System (ADS)

    Boezio, Mirko

    2016-07-01

    It was the 15th of June of 2006 when the PAMELA satellite-borne experiment was launched from the Baikonur cosmodrome in Kazakstan. Since then, PAMELA has been making high-precision measurements of the charged component of the cosmic radiation opening a new era of precision studies in cosmic rays. In this talk we will present the time dependence of the various components of the cosmic radiations from the unusual 23rd solar minimum through the following period of solar maximum activity. The detailed study of these components clearly shows the effects of solar modulation as well as charge sign dependence of the modulation.

  9. Long distance effect on ligand-gated ion channels extracellular domain may affect interactions with the intracellular machinery.

    PubMed

    Garret, Maurice; Boué-Grabot, Eric; Taly, Antoine

    2014-01-01

    Modulation of receptor trafficking is critical for controlling neurotransmission. A γ2(R43Q) point mutation on GABAA receptor subunit is linked to epilepsy in human. We recently analyzed the effect of this amino-acid substitution on GABAA receptor trafficking and showed that this mutation as well as agonist application, both affecting GABAA receptor extracellular domain, have an effect on receptor endocytosis. By comparing homology models based on ligand gated ion channels in their active and resting states, we reveal that the γ2R43 domain is located in a loop that is affected by motion resulting from receptor activation. Taken together, these results suggest that endocytosis of GABAA receptors is linked to agonist induced conformational changes. We propose that ligand or modulator binding is followed by a whole chain of interconnections, including the intracellular domain, that may influence ligand-gated channel trafficking.

  10. Long distance effect on ligand-gated ion channels extracellular domain may affect interactions with the intracellular machinery

    PubMed Central

    Garret, Maurice; Boué-Grabot, Eric; Taly, Antoine

    2014-01-01

    Modulation of receptor trafficking is critical for controlling neurotransmission. A γ2(R43Q) point mutation on GABAA receptor subunit is linked to epilepsy in human. We recently analyzed the effect of this amino-acid substitution on GABAA receptor trafficking and showed that this mutation as well as agonist application, both affecting GABAA receptor extracellular domain, have an effect on receptor endocytosis. By comparing homology models based on ligand gated ion channels in their active and resting states, we reveal that the γ2R43 domain is located in a loop that is affected by motion resulting from receptor activation. Taken together, these results suggest that endocytosis of GABAA receptors is linked to agonist induced conformational changes. We propose that ligand or modulator binding is followed by a whole chain of interconnections, including the intracellular domain, that may influence ligand-gated channel trafficking. PMID:25254078

  11. A Kind of Expertise Reversal Effect: Personalisation Effect Can Depend on Domain-Specific Prior Knowledge

    ERIC Educational Resources Information Center

    Stiller, Klaus D.; Jedlicka, Rosemarie

    2010-01-01

    In instructional multimedia design, it is often recommended that text accompanying pictures be presented in a personalised style to promote learning. The superiority of personalised over formal text is may be explained using social agency theory (Mayer, 2005b), but it has not been investigated empirically whether such effects are valid in…

  12. Cosmic Rays and Experiment CZELTA

    SciTech Connect

    Smolek, Karel; Nyklicek, Michal

    2007-11-26

    This paper gives a review of the physics of cosmic rays with emphasis on the methods of detection and study. A summary is given of the Czech project CZELTA which is part of a multinational program to study cosmic rays with energies above 10{sup 14} eV.

  13. Superbubbles and Local Cosmic Rays

    NASA Technical Reports Server (NTRS)

    Streitmatter, Robert E.; Jones, Frank C.

    2005-01-01

    We consider the possibility that distinctive features of the local cosmic ray spectra and composition are influenced by the Solar system being embedded within the cavity of an ancient superbubble. Shifts in the measured cosmic ray composition between 10(exp 11) and 10(exp 20) eV as well as the "knee" and "second knee" may be understood in this picture.

  14. Testing Galactic Cosmic Ray Models

    NASA Technical Reports Server (NTRS)

    Adams, James H., Jr.

    2009-01-01

    Models of the Galactic Cosmic Ray Environment are used for designing and planning space missions. The existing models will be reviewed. Spectral representations from these models will be compared with measurements of galactic cosmic ray spectra made on balloon flights and satellite flights over a period of more than 50 years.

  15. Testing Galactic Cosmic Ray Models

    NASA Technical Reports Server (NTRS)

    Adams, James H., Jr.

    2010-01-01

    Models of the Galactic Cosmic Ray Environment are used for designing and planning space missions. The exising models will be reviewed. Spectral representations from these models will be compared with measurements of galactic cosmic ray spectra made on balloon flights and satellite flights over a period of more than 50 years.

  16. Searching for signatures of cosmic superstrings in the CMB

    SciTech Connect

    Danos, Rebecca J.; Brandenberger, Robert H. E-mail: rhb@physics.mcgill.ca

    2010-02-01

    Because cosmic superstrings generically form junctions and gauge theoretic strings typically do not, junctions may provide a signature to distinguish between cosmic superstrings and gauge theoretic cosmic strings. In cosmic microwave background anisotropy maps, cosmic strings lead to distinctive line discontinuities. String junctions lead to junctions in these line discontinuities. In turn, edge detection algorithms such as the Canny algorithm can be used to search for signatures of strings in anisotropy maps. We apply the Canny algorithm to simulated maps which contain the effects of cosmic strings with and without string junctions. The Canny algorithm produces edge maps. To distinguish between edge maps from string simulations with and without junctions, we examine the density distribution of edges and pixels crossed by edges. We find that in string simulations without Gaussian noise (such as produced by the dominant inflationary fluctuations) our analysis of the output data from the Canny algorithm can clearly distinguish between simulations with and without string junctions. In the presence of Gaussian noise at the level expected from the current bounds on the contribution of cosmic strings to the total power spectrum of density fluctuations, the distinction between models with and without junctions is more difficult. However, by carefully analyzing the data the models can still be differentiated.

  17. Enhanced strain effect of aged acceptor-doped BaTiO3 ceramics with clamping domain structures

    NASA Astrophysics Data System (ADS)

    Wang, Lei; Zhou, Zhiyong; Zhao, Xiaobo; Liu, Zhen; Liang, Ruihong; Dong, Xianlin

    2017-03-01

    A clamping domain structure is proposed to improve the amount of non-180° domain switching in BaTiO3 based piezoelectric ceramics. Experimental results show a large unipolar strain of 0.23% at 5 kV/mm in aged 0.5 mol. % Mn doped BaTiO3 ceramics with clamping domain structures, and the normalized strain (d33*= Smax/Emax) reaches 600 pm/V at low electric fields of 2 or 3 kV/mm. In contrast, pure BaTiO3 ceramics with clamping domain structures exhibit no clear polarization constriction or strain enhancement at 3 kV/mm. Electron paramagnetic resonance spectra verify the existence of titanium vacancies, Mn2+ and Mn4+, in 0.5 mol. % Mn doped BaTiO3 ceramics. These results indicate that the enhanced strain effect can be attributed to the combined effect of the clamping domain structure and stabilization of defect dipoles. This method provides a general way to obtain large strain in ferroelectrics.

  18. Lipid domains in zwitterionic-anionic lipid mixtures induced by combined effect of monovalent and divalent ions

    NASA Astrophysics Data System (ADS)

    Xu, Hongcheng; Ganesan, Sai; Matysiak, Silvina

    Lipid domain formation is an important process for many cellular processes. In experiment, the effects of Ba2+, Sr2+, Ca2+ and Mg2+ in inducing lateral phase separation in the binary phosphatidylcholine-phosphatidylserine (PC-PS) bilayer are quite different, of which the molecular mechanism remains to be understood. We have explored the effect of monovalent (MI) and divalent (MII) cationic radii on lipid domain formation in mixed zwitterionic-anionic lipid bilayers. We propose a mechanism for the formation of divalent-cation-induced lipid domains based on MD simulations with our Water-Explicit Polarizable MEMbrane (WEPMEM) coarse-grained model, which uses PC as the model for zwitterionic and PS for anionic lipids. Lipid aggregation only occurs with limited range of monovalent and divalent ion sizes in agreement with experimental observations. More ordering and closer packing of the lipids are noted within the domains, which correlate with bilayer thickness, curvature and lipid asymmetry. The results of the simulations reveal that the lipid domain consists of MII-mediated anionic lipid dimer/trimer complexes bridged by monovalent ions MI and provide a stereochemical insight in understanding the experimentally observed calcium-induced phase separation.

  19. Effect of the centrifugal force on domain chaos in Rayleigh-Bénard convection.

    PubMed

    Becker, Nathan; Scheel, J D; Cross, M C; Ahlers, Guenter

    2006-06-01

    Experiments and simulations from a variety of sample sizes indicated that the centrifugal force significantly affects the domain-chaos state observed in rotating Rayleigh-Bénard convection-patterns. In a large-aspect-ratio sample, we observed a hybrid state consisting of domain chaos close to the sample center, surrounded by an annulus of nearly stationary nearly radial rolls populated by occasional defects reminiscent of undulation chaos. Although the Coriolis force is responsible for domain chaos, by comparing experiment and simulation we show that the centrifugal force is responsible for the radial rolls. Furthermore, simulations of the Boussinesq equations for smaller aspect ratios neglecting the centrifugal force yielded a domain precession-frequency f approximately epsilon(mu) with mu approximately equal to 1 as predicted by the amplitude-equation model for domain chaos, but contradicted by previous experiment. Additionally the simulations gave a domain size that was larger than in the experiment. When the centrifugal force was included in the simulation, mu and the domain size were consistent with experiment.

  20. Genuine cosmic hair

    NASA Astrophysics Data System (ADS)

    Kastor, David; Ray, Sourya; Traschen, Jennie

    2017-02-01

    We show that asymptotically future de Sitter (AFdS) spacetimes carry ‘genuine’ cosmic hair; information that is analogous to the mass and angular momentum of asymptotically flat spacetimes and that characterizes how an AFdS spacetime approaches its asymptotic form. We define new ‘cosmological tension’ charges associated with future asymptotic spatial translation symmetries, which are analytic continuations of the ADM mass and tensions of asymptotically planar AdS spacetimes, and which measure the leading anisotropic corrections to the isotropic, exponential de Sitter expansion rate. A cosmological Smarr relation, holding for AFdS spacetimes having exact spatial translation symmetry, is derived. This formula relates cosmological tension, which is evaluated at future infinity, to properties of the cosmology at early times, together with a ‘cosmological volume’ contribution that is analogous to the thermodynamic volume of AdS black holes. Smarr relations for different spatial directions imply that the difference in expansion rates between two directions at late times is related in a simple way to their difference at early times. Hence information about the very early universe can be inferred from cosmic hair, which is potentially observable in a late time de Sitter phase. Cosmological tension charges and related quantities are evaluated for Kasner–de Sitter spacetimes, which serve as our primary examples.

  1. Cosmic Diffuse Analysis

    NASA Technical Reports Server (NTRS)

    Ryan, James M.

    1999-01-01

    The final analysis of the COMPTEL cosmic diffuse flux analysis is summarized in the accompanying figure. It shows the intensity of the cosmic diffuse flux spectrum measured jointly between the Virgo region and the South Galactic pole. This spectrum represents flux per unit solid angle over the range of 0.8 to 30 MeV. It contains the first positive measurement of the flux above 10 MeV. The spectrum merges smoothly with that measured with the EGRET instrument, starting at 30 MeV. It also merges smoothly with the latest results of the HEAO-1 measurements. However, the spectrum below is softer than the spectrum above the COMPTEL energy band. In the COMPTEL energy band there must exist a change in spectral shape as the source objects or processes change from the lower energy regime to the higher energy regime. The details of the analysis and the implications and meanings of the results are spelled out in the thesis of Dr. Cheenu Kappadath which is enclosed.

  2. 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.

  3. COSMIC monthly progress report

    NASA Technical Reports Server (NTRS)

    1993-01-01

    Activities of the Computer Software Management and Information Center (COSMIC) are summarized for the month of August, 1993. Tables showing the current inventory of programs available from COSMIC are presented and program processing and evaluation activities are discussed. Ten articles were prepared for publication in the NASA Tech Brief Journal. These articles (included in this report) describe the following software items: (1) MOM3D - A Method of Moments Code for Electromagnetic Scattering (UNIX Version); (2) EM-Animate - Computer Program for Displaying and Animating the Steady-State Time-Harmonic Electromagnetic Near Field and Surface-Current Solutions; (3) MOM3D - A Method of Moments Code for Electromagnetic Scattering (IBM PC Version); (4) M414 - MIL-STD-414 Variable Sampling Procedures Computer Program; (5) MEDOF - Minimum Euclidean Distance Optimal Filter; (6) CLIPS 6.0 - C Language Integrated Production System, Version 6.0 (Macintosh Version); (7) CLIPS 6.0 - C Language Integrated Production System, Version 6.0 (IBM PC Version); (8) CLIPS 6.0 - C Language Integrated Production System, Version 6.0 (UNIX Version); (9) CLIPS 6.0 - C Language Integrated Production System, Version 6.0 (DEC VAX VMS Version); and (10) TFSSRA - Thick Frequency Selective Surface with Rectangular Apertures. Activities in the areas of marketing, customer service, benefits identification, maintenance and support, and dissemination are also described along with a budget summary.

  4. Testing Cosmic Inflation

    NASA Technical Reports Server (NTRS)

    Chuss, David

    2010-01-01

    The Cosmic Microwave Background (CMB) has provided a wealth of information about the history and physics of the early Universe. Much progress has been made on uncovering the emerging Standard Model of Cosmology by such experiments as COBE and WMAP, and ESA's Planck Surveyor will likely increase our knowledge even more. Despite the success of this model, mysteries remain. Currently understood physics does not offer a compelling explanation for the homogeneity, flatness, and the origin of structure in the Universe. Cosmic Inflation, a brief epoch of exponential expansion, has been posted to explain these observations. If inflation is a reality, it is expected to produce a background spectrum of gravitational waves that will leave a small polarized imprint on the CMB. Discovery of this signal would give the first direct evidence for inflation and provide a window into physics at scales beyond those accessible to terrestrial particle accelerators. I will briefly review aspects of the Standard Model of Cosmology and discuss our current efforts to design and deploy experiments to measure the polarization of the CMB with the precision required to test inflation.

  5. Cosmic Ray Physics at CERN

    NASA Astrophysics Data System (ADS)

    Fernandéz, A.; Gámez, E.; López, R.; Román, S.; Zepeda, A.

    2003-06-01

    In recent decades, cosmic ray air showers initiated by high-energy proton or nucleus collisions in the atmosphere have been studied with large area experiments on the surface of the Earth or with muon measurements deep underground. In principle, these cosmic ray experiments explore two completely different realms of physics, particle astrophysics and particle interaction physics, which are, however, intimately related by the interpretation of the data. In this paper we briefly review the cosmic ray physics activities developed at CERN in the last years. In particular we present some results from a small underground cosmic ray experiment and we discuss the capabilities of ALICE to detect high multiplicity muon events arising from cosmic ray air showers and some other astroparticle phenomena.

  6. Effects of tau domain-specific antibodies and intravenous immunoglobulin on tau aggregation and aggregate degradation.

    PubMed

    Esteves-Villanueva, Jose O; Trzeciakiewicz, Hanna; Loeffler, David A; Martić, Sanela

    2015-01-20

    Tau pathology, including neurofibrillary tangles, develops in Alzheimer's disease (AD). The aggregation and hyperphosphorylation of tau are potential therapeutic targets for AD. Administration of anti-tau antibodies reduces tau pathology in transgenic "tauopathy" mice; however, the optimal tau epitopes and conformations to target are unclear. Also unknown is whether intravenous immunoglobulin (IVIG) products, currently being evaluated in AD trials, exert effects on pathological tau. This study examined the effects of anti-tau antibodies targeting different tau epitopes and the IVIG Gammagard on tau aggregation and preformed tau aggregates. Tau aggregation was assessed by transmission electron microscopy and fluorescence spectroscopy, and the binding affinity of the anti-tau antibodies for tau was evaluated by enzyme-linked immunosorbent assays. Antibodies used were anti-tau 1-150 ("D-8"), anti-tau 259-266 ("Paired-262"), anti-tau 341-360 ("A-10"), and anti-tau 404-441 ("Tau-46"), which bind to tau's N-terminus, microtubule binding domain (MBD) repeat sequences R1 and R4, and the C-terminus, respectively. The antibodies Paired-262 and A-10, but not D-8 and Tau-46, reduced tau fibrillization and degraded preformed tau aggregates, whereas the IVIG reduced tau aggregation but did not alter preformed aggregates. The binding affinities of the antibodies for the epitope for which they were specific did not appear to be related to their effects on tau aggregation. These results confirm that antibody binding to tau's MBD repeat sequences may inhibit tau aggregation and indicate that such antibodies may also degrade preformed tau aggregates. In the presence of anti-tau antibodies, the resulting tau morphologies were antigen-dependent. The results also suggested the possibility of different pathways regulating antibody-mediated inhibition of tau aggregation and antibody-mediated degradation of preformed tau aggregates.

  7. Effect of duty cycle in different frequency domains on SSVEP based BCI: a preliminary study.

    PubMed

    Huang, Gan; Yao, Lin; Zhang, Dingguo; Zhu, Xiangyang

    2012-01-01

    Compared with the well learned amplitude-frequency characteristic of Steady State Visual Evoked Potential (SSVEP), the effect of duty cycle is still unclear. In this work, the influence of duty cycle on SSVEP response is investigated in differnt frequency domains. The amplitude surface with the change of both frequencies and duty cycles is plotted. To get a stable response, the experiment arranged in 3 days, and each result is an average of 12 repetitions. It is interesting that the results from power spectral density (PSD) and canonical correlation analysis (CCA) method are not consistent. In addition, the relation between the fundamental component and its second harmonic component with the change of duty cycle is quite different at frequency of 7 Hz, 10 Hz and 13 Hz. Based on the amplitude surface, we try to configure the subject-specific SSVEP based BCI. The frequencies and duty cycles of the stimulus are selected corresponding to the higher SSVEP response in the amplitude surface. Cross validation results show a significant improvement in the performance for the adjustment of duty cycle.

  8. Protective effects of genetic inhibition of Discoidin Domain Receptor 1 in experimental renal disease.

    PubMed

    Kerroch, Monique; Alfieri, Carlo; Dorison, Aude; Boffa, Jean-Jacques; Chatziantoniou, Christos; Dussaule, Jean-Claude

    2016-02-16

    Chronic kidney disease is a progressive incurable pathology affecting millions of people. Intensive investigations aim to identify targets for therapy. We have previously demonstrated that abnormal expression of the Discoidin Domain Receptor 1 (DDR1) is a key factor of renal disease by promoting inflammation and fibrosis. The present study investigates whether blocking the expression of DDR1 after the initiation of renal disease can delay or arrest the progression of this pathology. Severe renal disease was induced by either injecting nephrotoxic serum (NTS) or performing unilateral ureteral obstruction in mice, and the expression of DDR1 was inhibited by administering antisense oligodeoxynucleotides either at 4 or 8 days after NTS (corresponding to early or more established phases of disease, respectively), or at day 2 after ligation. DDR1 antisense administration at day 4 stopped the increase of proteinuria and protected animals against the progression of glomeruloneprhitis, as evidenced by functional, structural and cellular indexes. Antisense administration at day 8 delayed progression -but to a smaller degree- of renal disease. Similar beneficial effects on renal structure and inflammation were observed with the antisense administration of DDR1 after ureteral ligation. Thus, targeting DDR1 can be a promising strategy in the treatment of chronic kidney disease.

  9. Effect of Attachment Styles to Parents on Sexual Dysfunction Domains of Married Women

    PubMed Central

    Nia, Anvar Sadat Nayebi; Salari, Parvin; Sharifi, Nasibeh; Nooghani, Hadi Jabbari

    2017-01-01

    Introduction According to Bowbly attachment theory, attachment of a baby and its main care provider, influences on social growth and the baby’s feelings throughout its life. The present study was performed aim to determine the effect of attachment style to parents on domains of sexual dysfunction in married women. Methods This cross-sectional study was carried out on two hundred married women who were fertile, and referred private and governmental gynecology clinics in Mashhad, Iran, in 2014. Data collection tools were three questionnaires; Demographic and marital questionnaire, Female sexual function index questionnaire, and Adult attachment style questionnaire. Data were analyzed by SPSS version 20 (IBM© SPSS© Statistics version 20 using independent-samples t-test and logistic regression. The statistical tests were performed at the 95% confidence interval. Result Mean of safe attachment style to parents in all aspect of sexual dysfunction was significantly lower (p≤0.01), however, mean of distant attachment style to parents in all aspects of sexual dysfunction was significantly higher (p≤0.05). Conclusion Secure and distance attachment style to the mother showed maximum power of prediction for sexual dysfunction, which indicates the importance of attachment to parents and its impact on adult relationships. PMID:28243413

  10. Electrical detection of magnetic domain wall in Fe4N nanostrip by negative anisotropic magnetoresistance effect

    NASA Astrophysics Data System (ADS)

    Gushi, Toshiki; Ito, Keita; Higashikozono, Soma; Takata, Fumiya; Oosato, Hirotaka; Sugimoto, Yoshimasa; Toko, Kaoru; Honda, Syuta; Suemasu, Takashi

    2016-09-01

    The magnetic structure of the domain wall (DW) of a 30-nm-thick Fe4N epitaxial film with a negative spin polarization of the electrical conductivity is observed by magnetic force microscopy and is well explained by micromagnetic simulation. The Fe4N film is grown by molecular beam epitaxy on a SrTiO3(001) substrate and processed into arc-shaped ferromagnetic nanostrips 0.3 μm wide by electron beam lithography and reactive ion etching with Cl2 and BCl3 plasma. Two electrodes mounted approximately 12 μm apart on the nanostrip register an electrical resistance at 8 K. By changing the direction of an external magnetic field (0.2 T), the presence or absence of a DW positioned in the nanostrip between the two electrodes can be controlled. The resistance is increased by approximately 0.5 Ω when the DW is located between the electrodes, which signifies the negative anisotropic magnetoresistance effect of Fe4N. The electrical detection of the resistance change is an important step toward the electrical detection of current-induced DW motion in Fe4N.

  11. Stereoscopic displays in medical domains: a review of perception and performance effects

    NASA Astrophysics Data System (ADS)

    van Beurden, Maurice H. P. H.; van Hoey, Gert; Hatzakis, Haralambos; Ijsselsteijn, Wijnand A.

    2009-02-01

    In this paper we review empirical studies that investigate performance effects of stereoscopic displays for medical applications. We focus on four distinct application areas: diagnosis, pre-operative planning, minimally invasive surgery (MIS) and training/teaching. For diagnosis, stereoscopic displays can augment the understanding of complex spatial structures and increase the detection of abnormalities. Stereoscopic viewing of medical data has proven to increase the detection rate in breast imaging. A stereoscopic presentation of noisy and transparent images in 3D ultrasound results in better visualization of the internal structures, however more empirical studies are needed to confirm the clinical relevance. For MRI and CT, where images are frequently rendered in 3D perspective, the added value of binocular depth has not yet been convincingly demonstrated. For MIS, stereoscopic displays can decrease surgery time and increase accuracy of surgical procedures. Performance of surgical procedures is similar when high resolution 2D displays are compared with lower resolution stereoscopic displays, indicating an image quality improvement for stereoscopic displays. Training and surgical planning already use computer simulations in 2D, however more research is needed to the benefit of stereoscopic displays in those applications. Overall there is a clear need for more empirical evidence that quantifies the added value of stereoscopic displays in medical domains, such that the medical community will have ample basis to invest in stereoscopic displays in all or some of the described medical applications.

  12. Effect of some penetration enhancers on epithelial membrane lipid domains: evidence from fluorescence spectroscopy studies.

    PubMed

    Turunen, T M; Urtti, A; Paronen, P; Audus, K L; Rytting, J H

    1994-02-01

    The effect of the penetration enhancers Azone, oleic acid, 1-dodecanol, dodecyl N,N-dimethylaminoacetate (DDAA), and dodecyl N,N-dimethylaminoisopropionate (DDAIP) on epithelial membrane lipids was examined using human buccal cell membranes as a model for epithelial lipid bilayer. Buccal epithelial cells (BEC) were labeled with 1,6-diphenyl-1,3,5-hexatriene (DPH), 1-(4-(trimethylammonio)phenyl)-6- phenyl-1,3,5-hexatriene (TMA-DPH), and 8-anilino-1-naphthalene sulphonic acid (ANS) fluorophores to characterize enhancer-induced changes in the hydrophobic core, in the superficial polar head region, and on the exterior surface, respectively, with fluorescence anisotropy and fluorescence lifetimes. All the enhancers studied were found to decrease the BEC membrane lipid packing order in a concentration-dependent and time-dependent manner in the deep bilayer region, as shown by a 37-66% decrease in anisotropy. Oleic acid was also found to disrupt membrane lipids strongly in the polar head region, causing at least a 34% decrease in anisotropy values. Azone and DDAA were shown to alter molecular movement on the surface of the bilayers (24 and 19% decrease in anisotropy, respectively). The results suggest that interaction with membrane lipid domains is an important, but not the only, mode of action for the penetration enhancers studied.

  13. Quantifying ionospheric effects on time-domain astrophysics with the Murchison Widefield Array

    NASA Astrophysics Data System (ADS)

    Loi, Shyeh Tjing; Murphy, Tara; Bell, Martin E.; Kaplan, David L.; Lenc, Emil; Offringa, André R.; Hurley-Walker, Natasha; Bernardi, G.; Bowman, J. D.; Briggs, F.; Cappallo, R. J.; Corey, B. E.; Deshpande, A. A.; Emrich, D.; Gaensler, B. M.; Goeke, R.; Greenhill, L. J.; Hazelton, B. J.; Johnston-Hollitt, M.; Kasper, J. C.; Kratzenberg, E.; Lonsdale, C. J.; Lynch, M. J.; McWhirter, S. R.; Mitchell, D. A.; Morales, M. F.; Morgan, E.; Oberoi, D.; Ord, S. M.; Prabu, T.; Rogers, A. E. E.; Roshi, A.; Shankar, N. Udaya; Srivani, K. S.; Subrahmanyan, R.; Tingay, S. J.; Waterson, M.; Wayth, R. B.; Webster, R. L.; Whitney, A. R.; Williams, A.; Williams, C. L.

    2015-11-01

    Refraction and diffraction of incoming radio waves by the ionosphere induce time variability in the angular positions, peak amplitudes and shapes of radio sources, potentially complicating the automated cross-matching and identification of transient and variable radio sources. In this work, we empirically assess the effects of the ionosphere on data taken by the Murchison Widefield Array (MWA) radio telescope. We directly examine 51 h of data observed over 10 nights under quiet geomagnetic conditions (global storm index Kp < 2), analysing the behaviour of short-time-scale angular position and peak flux density variations of around ten thousand unresolved sources. We find that while much of the variation in angular position can be attributed to ionospheric refraction, the characteristic displacements (10-20 arcsec) at 154 MHz are small enough that search radii of 1-2 arcmin should be sufficient for cross-matching under typical conditions. By examining bulk trends in amplitude variability, we place upper limits on the modulation index associated with ionospheric scintillation of 1-3 per cent for the various nights. For sources fainter than ˜1 Jy, this variation is below the image noise at typical MWA sensitivities. Our results demonstrate that the ionosphere is not a significant impediment to the goals of time-domain science with the MWA at 154 MHz.

  14. Testing parity-violating physics from cosmic rotation power reconstruction

    NASA Astrophysics Data System (ADS)

    Namikawa, Toshiya

    2017-02-01

    We study the reconstruction of the cosmic rotation power spectrum produced by parity-violating physics, with an eye to ongoing and near future cosmic microwave background (CMB) experiments such as BICEP Array, CMBS4, LiteBIRD and Simons Observatory. In addition to the inflationary gravitational waves and gravitational lensing, measurements of other various effects on CMB polarization open new window into the early Universe. One of these is anisotropies of the cosmic polarization rotation which probes the Chern-Simons term generally predicted by string theory. The anisotropies of the cosmic rotation are also generated by the primordial magnetism and in the Standard Model extention framework. The cosmic rotation anisotropies can be reconstructed as quadratic in CMB anisotropies. However, the power of the reconstructed cosmic rotation is a CMB four-point correlation and is not directly related to the cosmic-rotation power spectrum. Understanding all contributions in the four-point correlation is required to extract the cosmic rotation signal. Assuming inflationary motivated cosmic-rotation models, we employ simulation to quantify each contribution to the four-point correlation and find that (1) a secondary contraction of the trispectrum increases the total signal-to-noise, (2) a bias from the lensing-induced trispectrum is significant compared to the statistical errors in, e.g., LiteBIRD and CMBS4-like experiments, (3) the use of a realization-dependent estimator decreases the statistical errors by 10%-20%, depending on experimental specifications, and (4) other higher-order contributions are negligible at least for near future experiments.

  15. Production and distribution of melt in domainal migmatite deciphered by micro-mapping the local effective bulk compositions

    NASA Astrophysics Data System (ADS)

    Lanari, Pierre; Riel, Nicolas; Engi, Martin

    2015-04-01

    Migmatites are fantastic targets to study the evolution of melt compositions, because they represent levels in the crust where partial melting has occurred. However, migmatites commonly have a complex history because they are the products of different transformation processes, such as (i) melt producing reactions, (ii) melt migration, and (iii) retrograde reactions. Evidence of such processes is preserved in the minerals and microstructures of rocks that outcrop in deeply exhumed orogens. The complexity of migmatites is due to their chemical and textural heterogeneity visible in different domains with various mineral assemblages. Partial melting of pelites involves reactions that are predictable using thermodynamic models. However, a forward modeling approach based on rock-specific equilibrium phase diagrams (P-T sections) requires the knowledge of local bulk composition for each equilibrium assemblage. This study demonstrates that suitable local effective bulk (LEB) compositions can be derived by means of standardized microprobe X-ray images, using the program XMAPTOOLS. For chemically heterogeneous samples, such as domanial migmatites, these LEB compositions allow the stable mineral assemblages to be modeled for each domain and to obtain reliable P-T estimates. A metapelite sample studied in detail derived from a metasedimentary xenolith in the Marcabeli pluton, El Oro Complex, Ecuador. This sample shows complex mineral patterns due to local melt redistribution (at mm to cm-scale), involving major changes that affected the local chemical composition observed today. Four domains are identified: A residuum domain made of cordierite + biotite + plagioclase + spinel, which is a metamorphic assemblage stable at P-Tmax conditions of 750 ± 50°C and 2 ± 1 kbar. In the leucosome (plagioclase + Kspar + quartz + biotite + orthopyroxene) three sub-domains show different mineral assemblages. Domain-specific equilibrium assemblages in the P-T sections demonstrate that these

  16. Dependence of effective internal field of congruent lithium niobate on its domain configuration and stability

    SciTech Connect

    Das, Ranjit E-mail: souvik2cat@gmail.com Ghosh, Souvik E-mail: souvik2cat@gmail.com Chakraborty, Rajib E-mail: souvik2cat@gmail.com

    2014-06-28

    Congruent lithium niobate is characterized by its internal field, which arises due to defect clusters within the crystal. Here, it is shown experimentally that this internal field is a function of the molecular configuration in a particular domain and also on the stability of that particular configuration. The measurements of internal field are done using interferometric technique, while the variation of domain configuration is brought about by room temperature high voltage electric field poling.

  17. Hubble space telescope/cosmic origins spectrograph observations of the quasar Q0302–003: Probing the He II reionization epoch and QSO proximity effects

    SciTech Connect

    Syphers, David; Shull, J. Michael

    2014-03-20

    Q0302–003 (z = 3.2860 ± 0.0005) was the first quasar discovered that showed a He II Gunn-Peterson trough, a sign of incomplete helium reionization at z ≳ 2.9. We present its Hubble Space Telescope/Cosmic Origins Spectrograph far-UV medium-resolution spectrum, which resolves many spectral features for the first time, allowing study of the quasar itself, the intergalactic medium, and quasar proximity effects. Q0302–003 has a harder intrinsic extreme-UV spectral index than previously claimed, as determined from both a direct fit to the spectrum (yielding α{sub ν} ≈ –0.8) and the helium-to-hydrogen ion ratio in the quasar's line-of-sight proximity zone. Intergalactic absorption along this sightline shows that the helium Gunn-Peterson trough is largely black in the range 2.87 < z < 3.20, apart from ionization due to local sources, indicating that helium reionization has not completed at these redshifts. However, we tentatively report a detection of nonzero flux in the high-redshift trough when looking at low-density regions, but zero flux in higher-density regions. This constrains the He II fraction to be about 1% in the low-density intergalactic medium (IGM) and possibly a factor of a few higher in the IGM as a whole, suggesting helium reionization has progressed substantially by z ∼ 3.1. The Gunn-Peterson trough recovers to a He II Lyα forest at z < 2.87. We confirm a transmission feature due to the ionization zone around a z = 3.05 quasar just off the sightline, and resolve the feature for the first time. We discover a similar such feature possibly caused by a luminous z = 3.23 quasar further from the sightline, which suggests that this quasar has been luminous for >34 Myr.

  18. Comparison of experimental data with predictions of various models for silicon and aluminum fragmentation under the effect of high-energy cosmic rays

    SciTech Connect

    Chechenin, N. G. Chuvilskaya, T. V.; Shirokova, A. A.; Kadmenskii, A. G.

    2011-12-15

    The accuracy attained in theoretically estimating the yields of isotopes and isobars and their energy, charge, and mass distributions in silicon fragmentation that occurs in spacecraft electronics under the effect of cosmic-ray protons is an important factor in forecasting the probability for single-event upsets in the electronics and the reliability of spacecraft operation in general. In previous studies of our group, it was shown that the results of the calculations are highly sensitive to the choice of parameters for opticalmodel potentials. In addition to cross sections for elastic and inelastic proton scattering and charge, mass, and energy distributions of heavy nuclear-reaction products, the results of our calculations for doubledifferential spectra of protons originating from the interaction of highly energetic (30-400 MeV) protons with aluminum and double-differential spectra of other particles (neutrons and alpha particles) arising in competing channels of the p + {sup 27}Al reaction are also described in the present article. The calculations in question were performed on the basis of the EMPIRE-II-19 code by using various optical-model potentials, including the Becchetti-Greenlees potential for the (p, n) channel, the Wilmore-Hodgson potential for the (p, n) channel, the Madland potential for the (p, p) channel, the Koning-Delaroche potential for the (p, p) channel, and the McFadden-Satchler potential for the (p, {alpha}) channel. A comparative analysis of the double-differential spectra obtained for outgoing protons, neutrons, and alpha particles experimentally and in the calculations of various authors was performed.

  19. The rise and fall of stellar across the peak of cosmic star formation history: effects of mergers versus diffuse stellar mass acquisition

    NASA Astrophysics Data System (ADS)

    Welker, C.; Dubois, Y.; Devriendt, J.; Pichon, C.; Kaviraj, S.; Peirani, S.

    2017-02-01

    Building galaxy merger trees from a state-of-the-art cosmological hydrodynamical simulation, Horizon-AGN, we perform a statistical study of how mergers and diffuse stellar mass acquisition processes drive galaxy morphologic properties above z > 1. By diffuse mass acquisition here, we mean both accretion of stars by unresolved mergers (relative stellar mass growth smaller than 4.5 per cent) as well as in situ star formation when no resolved mergers are detected along the main progenitor branch of a galaxy. We investigate how stellar densities, galaxy sizes and galaxy morphologies (defined via shape parameters derived from the inertia tensor of the stellar density) depend on mergers of different mass ratios. We investigate how stellar densities, effective radii and shape parameters derived from the inertia tensor depend on mergers of different mass ratios. We find strong evidence that diffuse stellar accretion and in situ formation tend to flatten small galaxies over cosmic time, leading to the formation of discs. On the other hand, mergers, and not only the major ones, exhibit a propensity to puff up and destroy stellar discs, confirming the origin of elliptical galaxies. We confirm that mergers grow galaxy sizes more efficiently than diffuse processes (r_{0.5}∝ M_s^{0.85} and r_{0.5}∝ M_s^{0.1} on average, respectively) and we also find that elliptical galaxies are more susceptible to grow in size through mergers than disc galaxies with a size-mass evolution r_{0.5}∝ M_s^{1.2} instead of r_{0.5}∝ M_s^{-0.5}-M^{0.5} for discs depending on the merger mass ratio. The gas content drives the size-mass evolution due to merger with a faster size growth for gas-poor galaxies r_{0.5}∝ M_s2 than for gas-rich galaxies r0.5 ∝ Ms.

  20. Low energy cosmic ray studies from a lunar base

    NASA Technical Reports Server (NTRS)

    Wiedenbeck, Mark E.

    1990-01-01

    Studies of cosmic ray nuclei with energies less than about 7 GeV/nucleon in low earth orbit are hampered by the geomagnetic field. Even in high inclination orbits these effects can be significant. The lunar surface (or lunar orbit) provides an attractive site for carrying out low energy cosmic ray studies which require large detectors. The rationale and requirements for this type of experiment are described.

  1. Low energy cosmic ray studies from a lunar base

    SciTech Connect

    Wiedenbeck, M.E. Department of Physics, University of Chicago, Chicago, IL )

    1990-03-15

    Studies of cosmic ray nuclei with energies {approx lt}7 GeV/nucleon in low Earth orbit are hampered by the geomagnetic field. Even in high inclination orbits these effects can be significant. The lunar surface (or lunar orbit) provides an attractive site for carrying out low energy cosmic ray studies which require large detectors. The rationale and requirements for this type of experiment are described.

  2. Shielding Effects of a Building Structure on the Energy Deposit of Cosmic Rays in a Simple Wavelength Shifter-Based Scintillator

    ERIC Educational Resources Information Center

    Aiola, Salvatore; La Rocca, Paola; Riggi, Francesco; Riggi, Simone

    2012-01-01

    An experimental setup, based on a plastic scintillator with an embedded wavelength shifter fibre and photosensors at the two ends, has been used to detect cosmic muons in undergraduate laboratory activities. Time and amplitude information from the two photosensors were measured using the time-over-threshold technique. The distribution of the…

  3. Effect of prolyl hydroxylase domain 2 haplodeficiency on liver progenitor cell characteristics in early mouse hepatocarcinogenesis

    PubMed Central

    Bogaerts, Eliene; Paridaens, Annelies; Verhelst, Xavier; Carmeliet, Peter; Geerts, Anja; Van Vlierberghe, Hans; Devisscher, Lindsey

    2016-01-01

    Activation of the hypoxia-inducible factor (HIF)-pathway in hepatocellular carcinoma (HCC) induces therapy resistant tumours, characterized by increased liver progenitor cell (LPCs) characteristics and poor prognosis. We previously reported corresponding results in mice with HCC in which hypoxia was mimicked by prolyl hydroxylase domain (PHD) inhibition. Here, we aimed at investigating whether induction of LPC characteristics occurs during the onset of hepatocarcinogenesis and if this is associated with activation of Notch signalling. Dietheylnitrosamine (DEN) was used to induce hepatic tumours in PHD2 haplodeficient (PHD2+/-) mice which were euthanized at 5, 10, 15 and 17 weeks following DEN during neoplastic transformation, before tumour formation. Neoplasia and mRNA expression of LPC and Notch markers were evaluated by histology and qPCR on isolated livers. PHD2 haplodeficiency resulted in enhanced expression of HIF target genes after 17 weeks of DEN compared to wild type (WT) littermates but had no effect on the onset of neoplastic transformation. The mRNA expression of Afp and Epcam was increased at all time points following DEN whereas CK19, Prom1 and Notch3 were increased after 17 weeks of DEN, without difference between PHD2+/- and WT mice. MDR1 mRNA expression was increased in all DEN treated mice compared to saline control with increased expression in PHD2+/- compared to WT from 15 weeks. These results indicate that the effects of PHD2 haplodeficiency on the expression of LPC and Notch markers manifest during tumour nodule formation and not early on during neoplastic transformation. PMID:28337100

  4. Distinct Neurobehavioural Effects of Cannabidiol in Transmembrane Domain Neuregulin 1 Mutant Mice

    PubMed Central

    Long, Leonora E.; Chesworth, Rose; Huang, Xu-Feng; Wong, Alexander; Spiro, Adena; McGregor, Iain S.; Arnold, Jonathon C.; Karl, Tim

    2012-01-01

    The cannabis constituent cannabidiol (CBD) possesses anxiolytic and antipsychotic properties. We have previously shown that transmembrane domain neuregulin 1 mutant (Nrg1 TM HET) mice display altered neurobehavioural responses to the main psychoactive constituent of cannabis, Δ9-tetrahydrocannabinol. Here we investigated whether Nrg1 TM HET mice respond differently to CBD and whether CBD reverses schizophrenia-related phenotypes expressed by these mice. Adult male Nrg1 TM HET and wild type-like littermates (WT) received vehicle or CBD (1, 50 or 100 mg/kg i.p.) for 21 days. During treatment and 48 h after withdrawal we measured behaviour, whole blood CBD concentrations and autoradiographic receptor binding. Nrg1 HET mice displayed locomotor hyperactivity, PPI deficits and reduced 5-HT2A receptor binding density in the substantia nigra, but these phenotypes were not reversed by CBD. However, long-term CBD (50 and 100 mg/kg) selectively enhanced social interaction in Nrg1 TM HET mice. Furthermore, acute CBD (100 mg/kg) selectively increased PPI in Nrg1 TM HET mice, although tolerance to this effect was manifest upon repeated CBD administration. Long-term CBD (50 mg/kg) also selectively increased GABAA receptor binding in the granular retrosplenial cortex in Nrg1 TM HET mice and reduced 5-HT2A binding in the substantia nigra in WT mice. Nrg1 appears necessary for CBD-induced anxiolysis since only WT mice developed decreased anxiety-related behaviour with repeated CBD treatment. Altered pharmacokinetics in mutant mice could not explain our findings since no genotype differences existed in CBD blood concentrations. Here we demonstrate that Nrg1 modulates acute and long-term neurobehavioural effects of CBD, which does not reverse the schizophrenia-relevant phenotypes. PMID:22509273

  5. Mediating effects of the ICF domain of function and the gross motor function measure on the ICF domains of activity, and participation in children with cerebral palsy.

    PubMed

    Lee, Byoung-Hee; Kim, Yu-Mi; Jeong, Goo-Churl

    2015-10-01

    [Purpose] This study aimed to evaluate the mediating effect of gross motor function, measured using the Gross Motor Function Measure (GMFM) and of general function, measured using the International Classification of Functioning, Disability and Health-Child and Youth Check List (ICF-CY), on the ICF domains of activity and participation in children with cerebral palsy (CP). [Subjects] Ninety-five children with CP, from Seoul, Korea, participated in the study. [Methods] The GMFM was administered in its entirety to patients without orthoses or mobility aids. The ICF-CY was used to evaluate the degree of disability and health of subjects. [Results] GMFM score and ICF-CY function were negatively correlated to ICF-CY activity and participation. ICF-CY partially mediated the effects of the GMFM on activity and participation. [Conclusion] When establishing a treatment plan for a child with CP, limitations in activity and participation, as described by the ICF-CY, should be considered in addition to the child's physical abilities and development. In addition, the treatment plan should focus on increasing the child's activity and participation level, as well as his/her physical level.

  6. Effect of lithographically-induced strain relaxation on the magnetic domain configuration in microfabricated epitaxially grown Fe81Ga19.

    PubMed

    Beardsley, R P; Parkes, D E; Zemen, J; Bowe, S; Edmonds, K W; Reardon, C; Maccherozzi, F; Isakov, I; Warburton, P A; Campion, R P; Gallagher, B L; Cavill, S A; Rushforth, A W

    2017-02-10

    We investigate the role of lithographically-induced strain relaxation in a micron-scaled device fabricated from epitaxial thin films of the magnetostrictive alloy Fe81Ga19. The strain relaxation due to lithographic patterning induces a magnetic anisotropy that competes with the magnetocrystalline and shape induced anisotropies to play a crucial role in stabilising a flux-closing domain pattern. We use magnetic imaging, micromagnetic calculations and linear elastic modelling to investigate a region close to the edges of an etched structure. This highly-strained edge region has a significant influence on the magnetic domain configuration due to an induced magnetic anisotropy resulting from the inverse magnetostriction effect. We investigate the competition between the strain-induced and shape-induced anisotropy energies, and the resultant stable domain configurations, as the width of the bar is reduced to the nanoscale range. Understanding this behaviour will be important when designing hybrid magneto-electric spintronic devices based on highly magnetostrictive materials.

  7. Effect of lithographically-induced strain relaxation on the magnetic domain configuration in microfabricated epitaxially grown Fe81Ga19

    NASA Astrophysics Data System (ADS)

    Beardsley, R. P.; Parkes, D. E.; Zemen, J.; Bowe, S.; Edmonds, K. W.; Reardon, C.; Maccherozzi, F.; Isakov, I.; Warburton, P. A.; Campion, R. P.; Gallagher, B. L.; Cavill, S. A.; Rushforth, A. W.

    2017-02-01

    We investigate the role of lithographically-induced strain relaxation in a micron-scaled device fabricated from epitaxial thin films of the magnetostrictive alloy Fe81Ga19. The strain relaxation due to lithographic patterning induces a magnetic anisotropy that competes with the magnetocrystalline and shape induced anisotropies to play a crucial role in stabilising a flux-closing domain pattern. We use magnetic imaging, micromagnetic calculations and linear elastic modelling to investigate a region close to the edges of an etched structure. This highly-strained edge region has a significant influence on the magnetic domain configuration due to an induced magnetic anisotropy resulting from the inverse magnetostriction effect. We investigate the competition between the strain-induced and shape-induced anisotropy energies, and the resultant stable domain configurations, as the width of the bar is reduced to the nanoscale range. Understanding this behaviour will be important when designing hybrid magneto-electric spintronic devices based on highly magnetostrictive materials.

  8. The effective penetration distance of ultrahigh-energy electrons and photons traversing a cosmic blackbody photon gas

    NASA Technical Reports Server (NTRS)

    Gould, R. J.; Rephaeli, Y.

    1978-01-01

    The effective average energy loss for an energetic (at least about 10 to the 15th power eV) particle traversing the microwave background radiation is evaluated. Electron-photon transformations by Compton scattering and pair production (in photon-photon collisions) are computed, with the energy loss considered to be carried away by the least energetic of the outgoing particles. Considering the most energetic of the outgoing particles as the high-energy particle, the relative probability and mean time for the particle to be a photon or electron (or positron) is evaluated. The effects of synchrotron losses for electrons and positrons are emphasized and compared with Compton losses to determine a critical energy (for given magnetic field) above which synchrotron losses dominate. Magnetic deflections are also treated for the case where the magnetic field is disordered, having a characteristic 'cell' size.

  9. Study on the biological effect of cosmic radiation and the development of radiation protection technology (L-11)

    NASA Technical Reports Server (NTRS)

    Nagaoka, Shunji

    1993-01-01

    NASDA is now participating in a series of flight experiments on Spacelab missions. The first experiment was carried out on the first International Microgravity Laboratory Mission (IML-1) January 1992, and the second experiment will be conducted on the Spacelab-J Mission, First Materials Processing Test (FMPT). The equipment or Radiation Monitoring Container Devices (RMCD) includes passive dosimeter systems and biological specimens. The experiments using this hardware are designed by NASDA to measure and investigate the radiation levels inside spacecraft like space shuttle and to look at the basic effects of the space environment from the aspect of radiation biology. The data gathered will be analyzed to understand the details of biological effects as well as the physical nature of space radiation registered in the sensitive Solid-State Track Detectors (SSTD).

  10. The dynamics of domain walls and strings

    NASA Technical Reports Server (NTRS)

    Gregory, Ruth; Haws, David; Garfinkle, David

    1989-01-01

    The leading order finite-width corrections to the equation of motion describing the motion of a domain wall are derived. The regime in which this equation of motion is invalid is discussed. Spherically and cylindrically symmetric solutions to this equation of motion are found. A misconception that has arisen in recent years regarding the rigidity (or otherwise) of cosmic strings is also clarified.

  11. Radiative Energy Loss by Galactic Cosmic Rays

    NASA Technical Reports Server (NTRS)

    Ahern, Sean C.; Norbury, John W.; Tripathi, R. K.

    2002-01-01

    Interactions between galactic cosmic rays and matter are a primary focus of the NASA radiation problem. The electromagnetic forces involved are for the most part well documented. Building on previous research, this study investigated the relative importance of the weak forces that occur when a cosmic ray impinges on different types of materials. For the familiar electromagnetic case, it is known that energy lost in the form of radiation is more significant than that lost via contact collisions the rate at which the energy is lost is also well understood. Similar results were derived for the weak force case. It was found that radiation is also the dominant mode of energy loss in weak force interactions and that weak force effects are indeed relatively weak compared to electromagnetic effects.

  12. Diffusion-convection function of cosmic rays

    NASA Technical Reports Server (NTRS)

    Zhang, G.; Yang, G.

    1985-01-01

    The fundamental properties and some numerical results of the solution of the diffusion equation of an impulsive cosmic-ray point source in an uniform, unbounded and spherically symmetrical moving medium is presented. The diffusion-convection(D-C) function is an elementary composite function of the solution of the D-C equation for the particles injected impulsively from a diffusive point source into the medium. It is the analytic solution derived by the dimensional method for the propagation equation of solar cosmic rays in the heliosphere, i.e. the interplanetary space. Because of the introduction of convection effect of solar wind, a nonhomogeneous term appears in the propagation equation, it is difficult to express its solution in terms of the ordinary special functions. The research made so far has led to a solution containing only the first order approximation of the convection effect.

  13. Effects of the bHLH domain on axial coordination of heme in the PAS-A domain of neuronal PAS domain protein 2 (NPAS2): conversion from His119/Cys170 coordination to His119/His171 coordination.

    PubMed

    Uchida, Takeshi; Sagami, Ikuko; Shimizu, Toru; Ishimori, Koichiro; Kitagawa, Teizo

    2012-03-01

    Neuronal PAS domain protein 2 (NPAS2), which is a CO-dependent transcription factor, consists of a basic helix-loop-helix domain (bHLH), and two heme-containing PAS domains (PAS-A and PAS-B). In our previous study on the isolated PAS-A domain, we concluded that His119 and Cys170 are the axial ligands of the ferric heme, while Cys170 is replaced by His171 upon reduction of heme (Uchida et al., J. Biol. Chem. 270, (2005) 21358-21368.). Recently, we characterized the PAS-A domain combined with the N-terminal bHLH domain, and found that some spectroscopic features were different from those of the isolated PAS-A domain (Mukaiyama et al., FEBS J. 273, (2006) 2528-2539.). Therefore, we reinvestigated the coordination structure of heme in the bHLH-PAS-A domain and prepared four histidine and one cysteine mutants. Resonance Raman spectrum of the Cys170Ala mutant is the same as that of wild type with a dominant 6-coordinate heme in the ferric form. In contrast, His119Ala and His171Ala mutants significantly increase amounts of the 5-coordinate species, indicating that His119 and His171, not Cys170, are axial ligands of the ferric heme in the bHLH-PAS-A domain. We had confirmed that the coordination structure of the isolated PAS-A domain is in equilibrium between Cys-Fe-His and His-Fe-His coordinated species but newly found that interaction of the PAS-A domain with the bHLH domain shifts the equilibrium toward the latter structure. Such flexibility in the heme coordination structure seems to be in favor of signal transduction in NPAS2.

  14. Chaperone-Like Effect of the Linker on the Isolated C-Terminal Domain of Rabbit Muscle Creatine Kinase

    PubMed Central

    Chen, Zhe; Chen, Xiang-Jun; Xia, Mengdie; He, Hua-Wei; Wang, Sha; Liu, Huihui; Gong, Haipeng; Yan, Yong-Bin

    2012-01-01

    Intramolecular chaperones (IMCs), which are specific domains/segments encoded in the primary structure of proteins, exhibit chaperone-like activity against the aggregation of the other domains in the same molecule. In this research, we found that the truncation of the linker greatly promoted the thermal aggregation of the isolated C-terminal domain (CTD) of rabbit muscle creatine kinase (RMCK). Either the existence of the linker covalently linked to CTD or the supply of the synthetic linker peptide additionally could successfully protect the CTD of RMCK against aggregation in a concentration-dependent manner. Truncated fragments of the linker also behaved as a chaperone-like effect with lower efficiency, revealing the importance of its C-terminal half in the IMC function of the linker. The aggregation sites in the CTD of RMCK were identified by molecular dynamics simulations. Mutational analysis of the three key hydrophobic residues resulted in opposing effects on the thermal aggregation between the CTD with intact or partial linker, confirming the role of linker as a lid to protect the hydrophobic residues against exposure to solvent. These observations suggested that the linkers in multidomain proteins could act as IMCs to facilitate the correct folding of the aggregation-prone domains. Furthermore, the intactness of the IMC linker after proteolysis modulates the production of off-pathway aggregates, which may be important to the onset of some diseases caused by the toxic effects of aggregated proteolytic fragments. PMID:22947872

  15. 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.

  16. Cosmic rays, thunderstorm clouds, and possible influence on climate, 2. Atmospheric electric field effect in different neutron multiplicities according to Emilio Segre Observatory one minute data

    NASA Astrophysics Data System (ADS)

    Dorman, L.; Dorman, I.; Iucci, N.; Eman, Y. Ne; Parisi, M.; Pustil Nik, L.; Signoretti, F.; Sternlieb, A.; Villoresi, G.; Zukerman, I.

    On the basis of cosmic ray and atmospheric electric field one minute data obtained by NM and EFS of Emilio Segre' Observatory (hight 2025 m above s.l., cut-off rigidity for vertical direction 10.8 GV) we determine the atmospheric electric field effect in CR fortotal neutron intensity and for multiplicities m 1, m 2, m 3, m 4, m 5, m 6, m7, and m8, as well as for m=1, m=2, m=3, m=4, m=5, m=6, and m=7. For comparison and excluding primary CR variations we use also one minute data on neutron multiplicities obtained by NM of University "Roma Tre" (about sea level, cut-off rigidity 6.7 GV). In February 2000 were observed 14 periods of thunderstorms with different durations (up to about 1000 min), the maximum strength of electric field was 110 kV/m. Thunderstorms were observed also in March 2000 (6 periods with maximal field 112 kV/m), in April 2000 (9; 70 kV/m), in May 2000 (4; 10 kV/m), in October 2000 (10; 70 kV/m), in November 2000 (5; 50 kV/m), in December 2000 (7; 88 kV/m), in January 2001 (12; 62 kV/m), in February 2001 (10; 88 kV/m). According to the theoretical calculations of Dorman and Dorman (2002) the electric field effect in the NM counting rate must be caused mainly by captchuring of slow negative muons by lead nucleus with escaping few neutrons. As it was shown in Dorman and Dorman (2002), the biggest electric field effect is expected in the multiplicity m=1, much smaller in m=2 and negligible effect is expected in higher multiplicities. We control this conclusion on the basis of our experimental data. Obtained results give a possibility to estimate total acceleration and deceleration of CR particles by the atmospheric electric field. We consider also the possible influence of CR air ionization (especially by secondary energetic electrons) on thunderstorms and lightnings, and through this - on climate. REFERENCES: Dorman L.I. and Dorman I.V., 2002. Report on COSPAR2002

  17. Fundamentals of Aerospace Medicine: Cosmic Radiation

    NASA Technical Reports Server (NTRS)

    Bagshaw, Michael; Cucionotta, Francis A.

    2007-01-01

    Cosmic rays were discovered in 1911 by the Austrian physicist, Victor Hess. The planet earth is continuously bathed in high-energy galactic cosmic ionizing radiation (GCR), emanating from outside the solar system, and sporadically exposed to bursts of energetic particles from the sun referred to as solar particle events (SPEs). The main source of GCR is believed to be supernovae (exploding stars), while occasionally a disturbance in the sun's atmosphere (solar flare or coronal mass ejection) leads to a surge of radiation particles with sufficient energy to penetrate the earth's magnetic field and enter the atmosphere. The inhabitants of planet earth gain protection from the effects of cosmic radiation from the earth s magnetic field and the atmosphere, as well as from the sun's magnetic field and solar wind. These protective effects extend to the occupants of aircraft flying within the earth s atmosphere, although the effects can be complex for aircraft flying at high altitudes and high latitudes. Travellers in space do not have the benefit of this protection and are exposed to an ionizing radiation field very different in magnitude and quality from the exposure of individuals flying in commercial airliners. The higher amounts and distinct types of radiation qualities in space lead to a large need for understanding the biological effects of space radiation. It is recognized that although there are many overlaps between the aviation and the space environments, there are large differences in radiation dosimetry, risks and protection for airline crew members, passengers and astronauts. These differences impact the application of radiation protection principles of risk justification, limitation, and the principle of as low as reasonably achievable (ALARA). This chapter accordingly is divided into three major sections, the first dealing with the basic physics and health risks, the second with the commercial airline experience, and the third with the aspects of cosmic

  18. Cosmic strings and baryon decay catalysis

    NASA Technical Reports Server (NTRS)

    Gregory, Ruth; Perkins, W. B.; Davis, A.-C.; Brandenberger, R. H.

    1989-01-01

    Cosmic strings, like monopoles, can catalyze proton decay. For integer charged fermions, the cross section for catalysis is not amplified, unlike in the case of monopoles. The catalysis processes are reviewed both in the free quark and skyrmion pictures and the implications for baryogenesis are discussed. A computation of the cross section for monopole catalyzed skyrmion decay is presented using classical physics. Also discussed are some effects which can screen catalysis processes.

  19. THE COSMIC ORIGINS SPECTROGRAPH

    SciTech Connect

    Green, James C.; Michael Shull, J.; Snow, Theodore P.; Stocke, John; Froning, Cynthia S.; Osterman, Steve; Beland, Stephane; Burgh, Eric B.; Danforth, Charles; France, Kevin; Ebbets, Dennis; Heap, Sara H.; Leitherer, Claus; Sembach, Kenneth; Linsky, Jeffrey L.; Savage, Blair D.; Siegmund, Oswald H. W.; Spencer, John; Alan Stern, S.; Welsh, Barry; and others

    2012-01-01

    The Cosmic Origins Spectrograph (COS) is a moderate-resolution spectrograph with unprecedented sensitivity that was installed into the Hubble Space Telescope (HST) in 2009 May, during HST Servicing Mission 4 (STS-125). We present the design philosophy and summarize the key characteristics of the instrument that will be of interest to potential observers. For faint targets, with flux F{sub {lambda}} Almost-Equal-To 1.0 Multiplication-Sign 10{sup -14} erg cm{sup -2} s{sup -1} A{sup -1}, COS can achieve comparable signal to noise (when compared to Space Telescope Imaging Spectrograph echelle modes) in 1%-2% of the observing time. This has led to a significant increase in the total data volume and data quality available to the community. For example, in the first 20 months of science operation (2009 September-2011 June) the cumulative redshift pathlength of extragalactic sight lines sampled by COS is nine times than sampled at moderate resolution in 19 previous years of Hubble observations. COS programs have observed 214 distinct lines of sight suitable for study of the intergalactic medium as of 2011 June. COS has measured, for the first time with high reliability, broad Ly{alpha} absorbers and Ne VIII in the intergalactic medium, and observed the He II reionization epoch along multiple sightlines. COS has detected the first CO emission and absorption in the UV spectra of low-mass circumstellar disks at the epoch of giant planet formation, and detected multiple ionization states of metals in extra-solar planetary atmospheres. In the coming years, COS will continue its census of intergalactic gas, probe galactic and cosmic structure, and explore physics in our solar system and Galaxy.

  20. Cosmic Dust Catalog

    NASA Astrophysics Data System (ADS)

    Warren, J.; Watts, L.; Thomas-Keprta, K.; Wentworth, S.; Dodson, A.; Zolensky, Michael E.

    1997-07-01

    Since May 1981, the National Aeronautics and Space Administration (NASA) has used aircraft to collect cosmic dust (CD) particles from Earth's stratosphere. Specially designed dust collectors are prepared for flight and processed after flight in an ultraclean (Class-100) laboratory constructed for this purpose at the Lyndon B. Johnson Space Center (JSC) in Houston, Texas. Particles are individually retrieved from the collectors, examined and cataloged, and then made available to the scientific community for research. Cosmic dust thereby joins lunar samples and meteorites as an additional source of extraterrestrial materials for scientific study. This catalog summarizes preliminary observations on 468 particles retrieved from collection surfaces L2021 and L2036. These surfaces were flat plate Large Area Collectors (with a 300 cm2 surface area each) which was coated with silicone oil (dimethyl siloxane) and then flown aboard a NASA ER-2 aircraft during a series of flights that were made during January and February of 1994 (L2021) and June 7 through July 5 of 1994 (L2036). Collector L2021 was flown across the entire southern margin of the US (California to Florida), and collector L2036 was flown from California to Wallops Island, VA and on to New England. These collectors were installed in a specially constructed wing pylon which ensured that the necessary level of cleanliness was maintained between periods of active sampling. During successive periods of high altitude (20 km) cruise, the collectors were exposed in the stratosphere by barometric controls and then retracted into sealed storage container-s prior to descent. In this manner, a total of 35.8 hours of stratospheric exposure was accumulated for collector L2021, and 26 hours for collector L2036.

  1. The Cosmic Origins Spectrograph

    NASA Technical Reports Server (NTRS)

    Green, James C.; Froning, Cynthia S.; Osterman, Steve; Ebbets, Dennis; Heap, Sara H.; Leitherer, Claus; Linsky, Jeffrey L.; Savage, Blair D.; Sembach, Kenneth; Shull, J. Michael; Siegmund, Oswald H. W.; Snow, Theodore P.; Spencer, John; Stern, S. Alan; Stocke, John; Welsh, Barry; Beland, Stephane; Burgh, Eric B.; Danforth, Charles; France, Kevin; Keeney, Brian; McPhate, Jason; Penton, Steven V; Andrews, John; Morse, Jon

    2010-01-01

    The Cosmic Origins Spectrograph (COS) is a moderate-resolution spectrograph with unprecedented sensitivity that was installed into the Hubble Space Telescope (HST) in May 2009, during HST Servicing Mission 4 (STS-125). We present the design philosophy and summarize the key characteristics of the instrument that will be of interest to potential observers. For faint targets, with flux F(sub lambda) approximates 1.0 X 10(exp -14) ergs/s/cm2/Angstrom, COS can achieve comparable signal to noise (when compared to STIS echelle modes) in 1-2% of the observing time. This has led to a significant increase in the total data volume and data quality available to the community. For example, in the first 20 months of science operation (September 2009 - June 2011) the cumulative redshift pathlength of extragalactic sight lines sampled by COS is 9 times that sampled at moderate resolution in 19 previous years of Hubble observations. COS programs have observed 214 distinct lines of sight suitable for study of the intergalactic medium as of June 2011. COS has measured, for the first time with high reliability, broad Lya absorbers and Ne VIII in the intergalactic medium, and observed the HeII reionization epoch along multiple sightlines. COS has detected the first CO emission and absorption in the UV spectra of low-mass circumstellar disks at the epoch of giant planet formation, and detected multiple ionization states of metals in extra-solar planetary atmospheres. In the coming years, COS will continue its census of intergalactic gas, probe galactic and cosmic structure, and explore physics in our solar system and Galaxy.

  2. The Cosmic Origins Spectrograph

    NASA Astrophysics Data System (ADS)

    Green, James C.; Froning, Cynthia S.; Osterman, Steve; Ebbets, Dennis; Heap, Sara H.; Leitherer, Claus; Linsky, Jeffrey L.; Savage, Blair D.; Sembach, Kenneth; Shull, J. Michael; Siegmund, Oswald H. W.; Snow, Theodore P.; Spencer, John; Stern, S. Alan; Stocke, John; Welsh, Barry; Béland, Stéphane; Burgh, Eric B.; Danforth, Charles; France, Kevin; Keeney, Brian; McPhate, Jason; Penton, Steven V.; Andrews, John; Brownsberger, Kenneth; Morse, Jon; Wilkinson, Erik

    2012-01-01

    The Cosmic Origins Spectrograph (COS) is a moderate-resolution spectrograph with unprecedented sensitivity that was installed into the Hubble Space Telescope (HST) in 2009 May, during HST Servicing Mission 4 (STS-125). We present the design philosophy and summarize the key characteristics of the instrument that will be of interest to potential observers. For faint targets, with flux F λ ≈ 1.0 × 10-14 erg cm-2 s-1 Å-1, COS can achieve comparable signal to noise (when compared to Space Telescope Imaging Spectrograph echelle modes) in 1%-2% of the observing time. This has led to a significant increase in the total data volume and data quality available to the community. For example, in the first 20 months of science operation (2009 September-2011 June) the cumulative redshift pathlength of extragalactic sight lines sampled by COS is nine times than sampled at moderate resolution in 19 previous years of Hubble observations. COS programs have observed 214 distinct lines of sight suitable for study of the intergalactic medium as of 2011 June. COS has measured, for the first time with high reliability, broad Lyα absorbers and Ne VIII in the intergalactic medium, and observed the He II reionization epoch along multiple sightlines. COS has detected the first CO emission and absorption in the UV spectra of low-mass circumstellar disks at the epoch of giant planet formation, and detected multiple ionization states of metals in extra-solar planetary atmospheres. In the coming years, COS will continue its census of intergalactic gas, probe galactic and cosmic structure, and explore physics in our solar system and Galaxy.

  3. The effect of baryons on redshift space distortions and cosmic density and velocity fields in the EAGLE simulation

    NASA Astrophysics Data System (ADS)

    Hellwing, Wojciech A.; Schaller, Matthieu; Frenk, Carlos S.; Theuns, Tom; Schaye, Joop; Bower, Richard G.; Crain, Robert A.

    2016-09-01

    We use the Evolution and Assembly of GaLaxies and their Environments (EAGLE) galaxy formation simulation to study the effects of baryons on the power spectrum of the total matter and dark matter distributions and on the velocity fields of dark matter and galaxies. On scales k ≳ 4 h Mpc-1 the effect of baryons on the amplitude of the total matter power spectrum is greater than 1 per cent. The back-reaction of baryons affects the density field of the dark matter at the level of ˜3 per cent on scales of 1 ≤ k/( h Mpc-1) ≤ 5. The dark matter velocity divergence power spectrum at k ≲ 0.5 h Mpc-1 is changed by less than 1 per cent. The 2D redshift space power spectrum is affected at the level of ˜6 per cent at |k|≳ 1 h Mpc^{-1} (for μ > 0.5), but for |k|≤ 0.4 h Mpc^{-1} it differs by less than 1 per cent. We report vanishingly small baryonic velocity bias for haloes: the peculiar velocities of haloes with M200 > 3 × 1011 M⊙ (hosting galaxies with M* > 109 M⊙) are affected at the level of at most 1 km s-1, which is negligible for 1 per cent-precision cosmology. We caution that since EAGLE overestimates cluster gas fractions it may also underestimate the impact of baryons, particularly for the total matter power spectrum. Nevertheless, our findings suggest that for theoretical modelling of redshift space distortions and galaxy velocity-based statistics, baryons and their back-reaction can be safely ignored at the current level of observational accuracy. However, we confirm that the modelling of the total matter power spectrum in weak lensing studies needs to include realistic galaxy formation physics in order to achieve the accuracy required in the precision cosmology era.

  4. Solar modulation of galactic cosmic rays: Contemporary observations and theories

    NASA Technical Reports Server (NTRS)

    Forman, M. A.

    1986-01-01

    The flux of galactic cosmic rays inside the solar system is modulated by the action of the complex magnetic fields carried from the Sun by the solar wind. This is apparent from the recurrent decrease of about 20% in the intensity of relativistic cosmic rays during sunspot maximum compared to sunspot minimum, from transient decreases due to solar flares and many other more subtle effects observed by ground stations for the last 50 years. Spacecraft observations of the spatial and temporal variations of cosmic ray flux during the last ten years have shown that the solar wind and cosmic-ray modulation extend to at least 30 astronomical units in the ecliptic plane. Present best guesses are that it goes out to 100 or 200 AU, perhaps less over the poles. Theories describing the mechanism of solar modulation are outlined and the importance of having a firm understanding of this mechanism to the study of other astrophysical phenomena is discussed.

  5. Cosmic rays in the heliosphere

    NASA Technical Reports Server (NTRS)

    Webber, William R.

    1987-01-01

    The different types of cosmic ray particles and their role in the heliosphere are briefly described. The rates of various energetic particles were examined as a function of time and used to derive various differential energy gradients. The Pioneer and Voyager cosmic ray observations throughout the heliosphere are indeed giving a perspective on the three-dimensional character and size of the heliosphere. Most clearly the observations are emphasizing the role that transient variations in the outer heliosphere, and most likely the heliospheric boundary shock, play in the 11 year solar cycle modulation of cosmic rays.

  6. Reionization from cosmic string loops

    SciTech Connect

    Olum, Ken D.; Vilenkin, Alexander

    2006-09-15

    Loops formed from a cosmic string network at early times would act as seeds for early formation of halos, which would form galaxies and lead to early reionization. With reasonable guesses about astrophysical and string parameters, the cosmic string scale G{mu} must be no more than about 3x10{sup -8} to avoid conflict with the reionization redshift found by WMAP. The bound is much stronger for superstring models with a small string reconnection probability. For values near the bound, cosmic string loops may explain the discrepancy between the WMAP value and theoretical expectations.

  7. Assessing the effect of domain size over the Caribbean region using the PRECIS regional climate model

    NASA Astrophysics Data System (ADS)

    Centella-Artola, Abel; Taylor, Michael A.; Bezanilla-Morlot, Arnoldo; Martinez-Castro, Daniel; Campbell, Jayaka D.; Stephenson, Tannecia S.; Vichot, Alejandro

    2015-04-01

    This study investigates the sensitivity of the one-way nested PRECIS regional climate model (RCM) to domain size for the Caribbean region. Simulated regional rainfall patterns from experiments using three domains with horizontal resolution of 50 km are compared with ERA reanalysis and observed datasets to determine if there is an optimal RCM configuration with respect to domain size and the ability to reproduce important observed climate features in the Caribbean. Results are presented for the early wet season (May-July) and late wet season (August-October). There is a relative insensitivity to domain size for simulating some important features of the regional circulation and key rainfall characteristics e.g. the Caribbean low level jet and the mid summer drought (MSD). The downscaled precipitation has a systematically negative precipitation bias, even when the domain was extended to the African coast to better represent circulation associated with easterly waves and tropical cyclones. The implications for optimizing modelling efforts within resource-limited regions like the Caribbean are discussed especially in the context of the region's participation in global initiatives such as CORDEX.

  8. Radiation effect on domain and defect structure of BaTiO3 crystals

    NASA Astrophysics Data System (ADS)

    Fesenko, Evgeni G.; Lisinska-Czekaj, Agata; Czekaj, Dionizy; Surowiak, Zygmunt

    2003-10-01

    BaTiO3 single crystals were obtained by Remeika-method from solutions of melted salts and oxides. Radioactive Co60 isotope was employed as a source of γ-radiation. Three different radiation doses were applied: 1.2 x 107 rad, 3.0 x 108 rad, and 1.3 x 107 rad. Temperature of single crystals during irradiation did not exceed 313 K. A few batches of crystals were subjected to irradiation, namely: single crystals with natural surface (after the crystal was grown), single crystals with the etched surface layer and single crystals which had been subjected to an influence of the strong direct and alternating electric fields before exposure. Both domain and defect structure of single crystals was investigated by the etching method, decorating method, optical microscopy and scanning electron microscopy. It has been found that irradiation causes destabilization of the domain walls of the head-to-head-type with a negative charge screening spontaneous polarization (Ps). The negative domains in a positive matrix, which did not grow through the whole crystal body, were found to decay under the influence of radiation. In a place previously occupied by decaying negative domains, defect clusters are observed. The investigations have shown that there is a close correlation between the domain structure and the defect structure of BaTiO3 crystals.

  9. Effects of domain size on x-ray absorption spectra of boron nitride doped graphenes

    NASA Astrophysics Data System (ADS)

    Li, Xin; Hua, Weijie; Wang, Bo-Yao; Pong, Way-Faung; Glans, Per-Anders; Guo, Jinghua; Luo, Yi

    2016-08-01

    Doping is an efficient way to open the zero band gap of graphene. The control of the dopant domain size allows us to tailor the electronic structure and the properties of the graphene. We have studied the electronic structure of boron nitride doped graphenes with different domain sizes by simulating their near-edge X-ray absorption fine structure (NEXAFS) spectra at the N K-edge. Six different doping configurations (five quantum dot type and one phase-separated zigzag-edged type) were chosen, and N K-edge NEXAFS spectra were calculated with large truncated cluster models by using the density functional theory with hybrid functional and the equivalent core hole approximation. The opening of the band gap as a function of the domain size is revealed. We found that nitrogens in the dopant boundary contribute a weaker, red-shifted π* peak in the spectra as compared to those in the dopant domain center. The shift is related to the fact that these interfacial nitrogens dominate the lowest conduction band of the system. Upon increasing the domain size, the ratio of interfacial atom decreases, which leads to a blue shift of the π* peak in the total NEXAFS spectra. The spectral evolution agrees well with experiments measured at different BN-dopant concentrations and approaches to that of a pristine h-BN sheet.

  10. Biological effects of individually synthesized TNF-binding domain of variola virus CrmB protein.

    PubMed

    Tsyrendorzhiev, D D; Orlovskaya, I A; Sennikov, S V; Tregubchak, T V; Gileva, I P; Tsyrendorzhieva, M D; Shchelkunov, S N

    2014-06-01

    The biological characteristics of a 17-kDa protein synthesized in bacterial cells, a TNF-binding domain (VARV-TNF-BP) of a 47-kDa variola virus CrmB protein (VARV-CrmB) consisting of TNF-binding and chemokine-binding domains, were studied. Removal of the C-terminal chemokine-binding domain from VARV-CrmB protein was inessential for the efficiency of its inhibition of TNF cytotoxicity towards L929 mouse fibroblast culture and for TNF-induced oxidative metabolic activity of mouse blood leukocytes. The results of this study could form the basis for further studies of VARV-TNF-BP mechanisms of activity for prospective use in practical medicine.

  11. Differential effect of H1 variant overproduction on gene expression is due to differences in the central globular domain.

    PubMed Central

    Brown, D T; Gunjan, A; Alexander, B T; Sittman, D B

    1997-01-01

    The in vivo overproduction of two mouse histone H1 variants in homologous mouse fibroblasts has opposite effects on gene expression. Overproduction of H1(0) results in repression of transcript levels of all polymerase II genes tested. In contrast, overproduction of H1c results in elevated levels of transcripts. We created a series of chimeric H1 genes in which the regions encoding the three structural domains common to this family of these proteins were systematically switched. Overexpression of these genes in vivo resulted in the accumulation of large amounts of the chimeric H1 in chromatin. Analysis of the effects of overproduction of these proteins revealed that the differential effect of H1 variant overproduction on gene expression is due to differences in the central globular domain. PMID:9396808

  12. Cosmic rays, solar activity and the climate

    NASA Astrophysics Data System (ADS)

    Sloan, T.; Wolfendale, A. W.

    2013-12-01

    Although it is generally believed that the increase in the mean global surface temperature since industrialization is caused by the increase in green house gases in the atmosphere, some people cite solar activity, either directly or through its effect on cosmic rays, as an underestimated contributor to such global warming. In this letter a simplified version of the standard picture of the role of greenhouse gases in causing the global warming since industrialization is described. The conditions necessary for this picture to be wholly or partially wrong are then introduced. Evidence is presented from which the contributions of either cosmic rays or solar activity to this warming is deduced. The contribution is shown to be less than 10% of the warming seen in the twentieth century.

  13. Paradigm transition in cosmic plasma physics

    NASA Technical Reports Server (NTRS)

    Alfven, H.

    1982-01-01

    New discoveries in cosmic plasma physics are described, and their applications to solar, interstellar, galactic, and cosmological problems are discussed. The new discoveries include the existence of double layers in magnetized plasmas and in the low magnetosphere, and energy transfer by electric current in the auroral circuit. It is argued that solar flares and the solar wind-magnetosphere interaction should not be interpreted in terms of magnetic merging theories, and that electric current needs to be explicitly taken account of in understanding these phenomena. The filamentary structure of cosmic plasmas may be caused by electric currents in space, and the pinch effect may have a central role to play in the evolutionary history of interstellar clouds, stars, and solar systems. Space may have a cellular structure, with the cell walls formed by thin electric current layers. Annihilation may be the source of energy for quasars and the Hubble expansion, and the big bang cosmology may well be wrong.

  14. How domain growth is implemented determines the long-term behavior of a cell population through its effect on spatial correlations

    NASA Astrophysics Data System (ADS)

    Ross, Robert J. H.; Baker, R. E.; Yates, C. A.

    2016-07-01

    Domain growth plays an important role in many biological systems, and so the inclusion of domain growth in models of these biological systems is important to understanding how these systems function. In this work we present methods to include the effects of domain growth on the evolution of spatial correlations in a continuum approximation of a lattice-based model of cell motility and proliferation. We show that, depending on the way in which domain growth is implemented, different steady-state densities are predicted for an agent population. Furthermore, we demonstrate that the way in which domain growth is implemented can result in the evolution of the agent density depending on the size of the domain. Continuum approximations that ignore spatial correlations cannot capture these behaviors, while those that account for spatial correlations do. These results will be of interest to researchers in developmental biology, as they suggest that the nature of domain growth can determine the characteristics of cell populations.

  15. High energy cosmic ray composition

    NASA Astrophysics Data System (ADS)

    Seo, E. S.

    Cosmic rays are understood to result from energetic processes in the galaxy, probably from supernova explosions. However, cosmic ray energies extend several orders of magnitude beyond the limit thought possible for supernova blast waves. Over the past decade several ground-based and space-based investigations were initiated to look for evidence of a limit to supernova acceleration in the cosmic-ray chemical composition at high energies. These high-energy measurements are difficult because of the very low particle fluxes in the most interesting regions. The space-based detectors must be large enough to collect adequate statistics, yet stay within the weight limit for space flight. Innovative approaches now promise high quality measurements over an energy range that was not previously possible. The current status of high energy cosmic-ray composition measurements and planned future missions are discussed in this paper.

  16. Determination of neutron monitor barometric effect on the base of the altitude cosmic ray intensity dependence as measured by the Israelo-Italian mobile laboratory

    NASA Astrophysics Data System (ADS)

    Dorman, L. I.

    In the way of transferring the Israelo-Italian moving laboratory with 6NM-64 neutron monitor from Italy to the place of stationary operation we did measurements of total neutron intensity, air pressure and intensities of neutron multiplicities m = 1, m = 2, m = 3, m = 4, m = 5, m = 6, m = 7 and m ≥ 8 in Haifa port (sea level, air pressure about 750 mmHg), in some intermediate points (about 626 mmHg), and in the final position of Emilio Segre' Observatory (33°18.3‧N, 35°47.2‧E, 2025 m above sea level, Rc = 10.8 GV ). By these data we determined first approximation cosmic ray barometric coefficients for total neutron component and for different neutron multiplicities (information on primary cosmic ray variations on the basis of Rome neutron monitor data have been taken into account).

  17. Personal Epistemology across Different Judgement Domains: Effects of Grade Level and School Curriculum

    ERIC Educational Resources Information Center

    Wang, Xinghua; Zhou, Ji; Shen, Jiliang

    2016-01-01

    This article reports a study that is based on the framework of personal epistemology proposed by Kuhn, Cheney, and Weinstock (2000). The instrument developed by Kuhn et al. (2000) for assessing the three positions (absolutist, multiplist and evaluativist) of epistemological understanding across five judgements' domains was translated and…

  18. Effect of Prior Domain Knowledge and Headings on Processing of Informative Text

    ERIC Educational Resources Information Center

    Surber, John R.; Schroeder, Mark

    2007-01-01

    College students with either high or low prior domain knowledge (PK) read a text chapter presented in short pages on a computer monitor. Half of the participants read with headings present and half with headings absent. The computer recorded time spent reading and rereading each short page. Learning was assessed through a structured recall task.…

  19. Paget disease of bone-associated UBA domain mutations of SQSTM1 exert distinct effects on protein structure and function

    PubMed Central

    Goode, Alice; Long, Jed E.; Shaw, Barry; Ralston, Stuart H.; Visconti, Micaela Rios; Gianfrancesco, Fernando; Esposito, Teresa; Gennari, Luigi; Merlotti, Daniela; Rendina, Domenico; Rea, Sarah L.; Sultana, Melanie; Searle, Mark S.; Layfield, Robert

    2014-01-01

    SQSTM1 mutations are common in patients with Paget disease of bone (PDB), with most affecting the C-terminal ubiquitin-associated (UBA) domain of the SQSTM1 protein. We performed structural and functional analyses of two UBA domain mutations, an I424S mutation relatively common in UK PDB patients, and an A427D mutation associated with a severe phenotype in Southern Italian patients. Both impaired SQSTM1's ubiquitin-binding function in pull-down assays and resulted in activation of basal NF-κB signalling, compared to wild-type, in reporter assays. We found evidence for a relationship between the ability of different UBA domain mutants to activate NF-κB signalling in vitro and number of affected sites in vivo in 1152 PDB patients from the UK and Italy, with A427D-SQSTM1 producing the greatest level of activation (relative to wild-type) of all PDB mutants tested to date. NMR and isothermal titration calorimetry studies were able to demonstrate that I424S is associated with global structural changes in the UBA domain, resulting in 10-fold weaker UBA dimer stability than wild-type and reduced ubiquitin-binding affinity of the UBA monomer. Our observations provide insights into the role of SQSTM1-mediated NF-κB signalling in PDB aetiology, and demonstrate that different mutations in close proximity within loop 2/helix 3 of the SQSTM1 UBA domain exert distinct effects on protein structure and stability, including indirect effects at the UBA/ubiquitin-binding interface. PMID:24642144

  20. Cosmic Rays and Particle Physics

    NASA Astrophysics Data System (ADS)

    Gaisser, Thomas K.; Engel, Ralph; Resconi, Elisa

    2016-06-01

    Preface to the first edition; Preface to the second edition; 1. Cosmic rays; 2. Cosmic ray data; 3. Particle physics; 4. Hadronic interactions and accelerator data; 5. Cascade equations; 6. Atmospheric muons and neutrinos; 7. Neutrino masses and oscillations; 8. Muons and neutrinos underground; 9. Cosmic rays in the Galaxy; 10. Extragalactic propagation of cosmic rays; 11. Astrophysical - rays and neutrinos; 12. Acceleration; 13. Supernovae in the Milky Way; 14. Astrophysical accelerators and beam dumps; 15. Electromagnetic cascades; 16. Extensive air showers; 17. Very high energy cosmic rays; 18. Neutrino astronomy; A.1. Units, constants and definitions; A.2. References to flux measurements; A.3. Particle flux, density, and interaction cross section; A.4. Fundamentals of scattering theory; A.5. Regge amplitude; A.6. Glauber model of nuclear cross sections; A.7. Earth's atmosphere; A.8. Longitudinal development of air showers; A.9. Secondary positrons and electrons; A.10. Liouville's theorem and cosmic ray propagation; A.11. Cosmology and distances measures; A.12. The Hillas splitting algorithm; References; Index.