WorldWideScience

Sample records for anisotropy probe observations

  1. Microwave Interstellar Medium Emission Observed by theWilkinson Microwave Anisotropy Probe

    OpenAIRE

    Finkbeiner, Douglas

    2004-01-01

    We investigate the nature of the diffuse Galactic emission in the Wilkinson Microwave Anisotropy Probe (WMAP) temperature anisotropy data. Substantial dust-correlated emission is observed at all WMAP frequencies, far exceeding the expected thermal dust emission in the lowest frequency channels (23, 33, and 41 GHz). The WMAP team interprets this emission as dust-correlated synchrotron radiation, attributing the correlation to the natural association of relativistic electrons produced by supern...

  2. Nine-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Final Maps and Results

    Science.gov (United States)

    Bennett, C. L.; Larson, D.; Weiland, J. L.; Jaorsik, N.; Hinshaw, G.; Odegard, N.; Smith, K. M.; Hill, R. S.; Gold, B.; Halpern, M; hide

    2013-01-01

    We present the final nine-year maps and basic results from the Wilkinson Microwave Anisotropy Probe (WMAP) mission. The full nine-year analysis of the time-ordered data provides updated characterizations and calibrations of the experiment. We also provide new nine-year full sky temperature maps that were processed to reduce the asymmetry of the effective beams. Temperature and polarization sky maps are examined to separate cosmic microwave background (CMB) anisotropy from foreground emission, and both types of signals are analyzed in detail.We provide new point source catalogs as well as new diffuse and point source foreground masks. An updated template-removal process is used for cosmological analysis; new foreground fits are performed, and new foreground reduced are presented.We nowimplement an optimal C(exp -1)1 weighting to compute the temperature angular power spectrum. The WMAP mission has resulted in a highly constrained Lambda-CDM cosmological model with precise and accurate parameters in agreement with a host of other cosmological measurements. When WMAP data are combined with finer scale CMB, baryon acoustic oscillation, and Hubble constant measurements, we find that big bang nucleosynthesis is well supported and there is no compelling evidence for a non-standard number of neutrino species (N(sub eff) = 3.84 +/- 0.40). The model fit also implies that the age of the universe is (sub 0) = 13.772 +/- 0.059 Gyr, and the fit Hubble constant is H(sub 0) = 69.32 +/- 0.80 km/s/ Mpc. Inflation is also supported: the fluctuations are adiabatic, with Gaussian random phases; the detection of a deviation of the scalar spectral index from unity, reported earlier by the WMAP team, now has high statistical significance (n(sub s) = 0.9608+/-0.0080); and the universe is close to flat/Euclidean (Omega = -0.0027+0.0039/-0.0038). Overall, the WMAP mission has resulted in a reduction of the cosmological parameter volume by a factor of 68,000 for the standard six

  3. Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Data Processing, Sky Maps, and Basic Results

    Science.gov (United States)

    Weiland, J.L.; Hill, R.S.; Odegard, 3.; Larson, D.; Bennett, C.L.; Dunkley, J.; Jarosik, N.; Page, L.; Spergel, D.N.; Halpern, M.; hide

    2008-01-01

    The Wilkinson Microwave Anisotropy Probe (WMAP) is a Medium-Class Explorer (MIDEX) satellite aimed at elucidating cosmology through full-sky observations of the cosmic microwave background (CMB). The WMAP full-sky maps of the temperature and polarization anisotropy in five frequency bands provide our most accurate view to date of conditions in the early universe. The multi-frequency data facilitate the separation of the CMB signal from foreground emission arising both from our Galaxy and from extragalactic sources. The CMB angular power spectrum derived from these maps exhibits a highly coherent acoustic peak structure which makes it possible to extract a wealth of information about the composition and history of the universe. as well as the processes that seeded the fluctuations. WMAP data have played a key role in establishing ACDM as the new standard model of cosmology (Bennett et al. 2003: Spergel et al. 2003; Hinshaw et al. 2007: Spergel et al. 2007): a flat universe dominated by dark energy, supplemented by dark matter and atoms with density fluctuations seeded by a Gaussian, adiabatic, nearly scale invariant process. The basic properties of this universe are determined by five numbers: the density of matter, the density of atoms. the age of the universe (or equivalently, the Hubble constant today), the amplitude of the initial fluctuations, and their scale dependence. By accurately measuring the first few peaks in the angular power spectrum, WMAP data have enabled the following accomplishments: Showing the dark matter must be non-baryonic and interact only weakly with atoms and radiation. The WMAP measurement of the dark matter density puts important constraints on supersymmetric dark matter models and on the properties of other dark matter candidates. With five years of data and a better determination of our beam response, this measurement has been significantly improved. Precise determination of the density of atoms in the universe. The agreement between

  4. NINE-YEAR WILKINSON MICROWAVE ANISOTROPY PROBE (WMAP) OBSERVATIONS: COSMOLOGICAL PARAMETER RESULTS

    International Nuclear Information System (INIS)

    Hinshaw, G.; Halpern, M.; Larson, D.; Bennett, C. L.; Weiland, J. L.; Komatsu, E.; Spergel, D. N.; Dunkley, J.; Nolta, M. R.; Hill, R. S.; Odegard, N.; Page, L.; Jarosik, N.; Smith, K. M.; Gold, B.; Kogut, A.; Wollack, E.; Limon, M.; Meyer, S. S.; Tucker, G. S.

    2013-01-01

    We present cosmological parameter constraints based on the final nine-year Wilkinson Microwave Anisotropy Probe (WMAP) data, in conjunction with a number of additional cosmological data sets. The WMAP data alone, and in combination, continue to be remarkably well fit by a six-parameter ΛCDM model. When WMAP data are combined with measurements of the high-l cosmic microwave background anisotropy, the baryon acoustic oscillation scale, and the Hubble constant, the matter and energy densities, Ω b h 2 , Ω c h 2 , and Ω Λ , are each determined to a precision of ∼1.5%. The amplitude of the primordial spectrum is measured to within 3%, and there is now evidence for a tilt in the primordial spectrum at the 5σ level, confirming the first detection of tilt based on the five-year WMAP data. At the end of the WMAP mission, the nine-year data decrease the allowable volume of the six-dimensional ΛCDM parameter space by a factor of 68,000 relative to pre-WMAP measurements. We investigate a number of data combinations and show that their ΛCDM parameter fits are consistent. New limits on deviations from the six-parameter model are presented, for example: the fractional contribution of tensor modes is limited to r k = -0.0027 +0.0039 -0.0038 ; the summed mass of neutrinos is limited to Σm ν eff = 3.84 ± 0.40, when the full data are analyzed. The joint constraint on N eff and the primordial helium abundance, Y He , agrees with the prediction of standard big bang nucleosynthesis. We compare recent Planck measurements of the Sunyaev-Zel'dovich effect with our seven-year measurements, and show their mutual agreement. Our analysis of the polarization pattern around temperature extrema is updated. This confirms a fundamental prediction of the standard cosmological model and provides a striking illustration of acoustic oscillations and adiabatic initial conditions in the early universe

  5. SEVEN-YEAR WILKINSON MICROWAVE ANISOTROPY PROBE (WMAP ) OBSERVATIONS: POWER SPECTRA AND WMAP-DERIVED PARAMETERS

    International Nuclear Information System (INIS)

    Larson, D.; Bennett, C. L.; Gold, B.; Dunkley, J.; Hinshaw, G.; Kogut, A.; Wollack, E.; Komatsu, E.; Nolta, M. R.; Halpern, M.; Hill, R. S.; Odegard, N.; Weiland, J. L.; Jarosik, N.; Page, L.; Limon, M.; Meyer, S. S.; Smith, K. M.; Spergel, D. N.; Tucker, G. S.

    2011-01-01

    The WMAP mission has produced sky maps from seven years of observations at L2. We present the angular power spectra derived from the seven-year maps and discuss the cosmological conclusions that can be inferred from WMAP data alone. With the seven-year data, the temperature (TT) spectrum measurement has a signal-to-noise ratio per multipole that exceeds unity for l m h 2 = 0.1334 +0.0056 -0.0055 , and on the epoch of matter-radiation equality, z eq = 3196 +134 -133 . The temperature-polarization (TE) spectrum is detected in the seven-year data with a significance of 20σ, compared to 13σ with the five-year data. We now detect the second dip in the TE spectrum near l ∼ 450 with high confidence. The TB and EB spectra remain consistent with zero, thus demonstrating low systematic errors and foreground residuals in the data. The low-l EE spectrum, a measure of the optical depth due to reionization, is detected at 5.5σ significance when averaged over l = 2-7: l(l + 1)C EE l /(2π) = 0.074 +0.034 -0.025 μK 2 (68% CL). We now detect the high-l, 24 ≤ l ≤ 800, EE spectrum at over 8σ. The BB spectrum, an important probe of gravitational waves from inflation, remains consistent with zero; when averaged over l = 2-7, l(l + 1)C BB l /(2π) 2 (95% CL). The upper limit on tensor modes from polarization data alone is a factor of two lower with the seven-year data than it was using the five-year data. The data remain consistent with the simple ΛCDM model: the best-fit TT spectrum has an effective χ 2 of 1227 for 1170 degrees of freedom, with a probability to exceed of 9.6%. The allowable volume in the six-dimensional space of ΛCDM parameters has been reduced by a factor of 1.5 relative to the five-year volume, while the ΛCDM model that allows for tensor modes and a running scalar spectral index has a factor of three lower volume when fit to the seven-year data. We test the parameter recovery process for bias and find that the scalar spectral index, n s , is biased

  6. Mass amplifying probe for sensitive fluorescence anisotropy detection of small molecules in complex biological samples.

    Science.gov (United States)

    Cui, Liang; Zou, Yuan; Lin, Ninghang; Zhu, Zhi; Jenkins, Gareth; Yang, Chaoyong James

    2012-07-03

    Fluorescence anisotropy (FA) is a reliable and excellent choice for fluorescence sensing. One of the key factors influencing the FA value for any molecule is the molar mass of the molecule being measured. As a result, the FA method with functional nucleic acid aptamers has been limited to macromolecules such as proteins and is generally not applicable for the analysis of small molecules because their molecular masses are relatively too small to produce observable FA value changes. We report here a molecular mass amplifying strategy to construct anisotropy aptamer probes for small molecules. The probe is designed in such a way that only when a target molecule binds to the probe does it activate its binding ability to an anisotropy amplifier (a high molecular mass molecule such as protein), thus significantly increasing the molecular mass and FA value of the probe/target complex. Specifically, a mass amplifying probe (MAP) consists of a targeting aptamer domain against a target molecule and molecular mass amplifying aptamer domain for the amplifier protein. The probe is initially rendered inactive by a small blocking strand partially complementary to both target aptamer and amplifier protein aptamer so that the mass amplifying aptamer domain would not bind to the amplifier protein unless the probe has been activated by the target. In this way, we prepared two probes that constitute a target (ATP and cocaine respectively) aptamer, a thrombin (as the mass amplifier) aptamer, and a fluorophore. Both probes worked well against their corresponding small molecule targets, and the detection limits for ATP and cocaine were 0.5 μM and 0.8 μM, respectively. More importantly, because FA is less affected by environmental interferences, ATP in cell media and cocaine in urine were directly detected without any tedious sample pretreatment. Our results established that our molecular mass amplifying strategy can be used to design aptamer probes for rapid, sensitive, and selective

  7. Mapping the CMB with the Wilkinson Microwave Anisotropy Probe

    Science.gov (United States)

    Hinshaw, Gary F.

    2007-01-01

    The data from the Wilkinson Microwave Anisotropy Probe (WMAP) satellite provide detailed full-sky maps of the cosmic microwave background temperature anisotropy and new full-sky maps of the polarization. Together, the data provide a wealth of cosmological information, including the age of the universe, the epoch when the first stars formed, and the overall composition of baryonic matter, dark matter, and dark energy. The results also provide constraints on the period of inflationary expansion in the very first moments of time. These and other aspects of the mission results will be discussed and commented on. WMAP, part of NASA's Explorers program, was launched on June 30,200 1. The WMAP satellite was produced in a partnership between the Goddard Space Flight Center and Princeton University. The WMAP team also includes researchers at the Johns Hopkins University; the Canadian Institute of Theoretical Astrophysics; University of Texas; University of Chicago; Brown University; University of British Columbia; and University of California, Los Angeles.

  8. Performance of the Microwave Anisotropy Probe AST-201 Star Trackers

    Science.gov (United States)

    Ward, David K.; vanBezooijen, Roelof; Bauer, Frank H. (Technical Monitor)

    2002-01-01

    The Microwave Anisotropy Probe (MAP) was launched to create a full-sky map of the cosmic microwave background. MAP incorporates two modified Lockheed Martin AST-201 (Autonomous Star Tracker) star trackers. The AST-201 employs an eight element radiation hardened lens assembly which is used to focus an image on a charge coupled device (CCD). The CCD image is then processed by a star identification algorithm which outputs a three-axis attitude. A CCD-shift algorithm called Time Delayed Integration (TDI) was also included in each star tracker. In order to provide some radiation effect filtering during MAP's three to five phasing loop passes through the Van Allen radiation belts, a simple pixel filtering scheme was implemented, rather than using a more complex, but more robust windowing algorithm. The trackers also include a fiber optic data interface. This paper details the ground testing that was accomplished on the MAP trackers.

  9. The Atacama Cosmology Telescope: Calibration with the Wilkinson Microwave Anisotropy Probe Using Cross-Correlations

    Science.gov (United States)

    Hajian, Amir; Acquaviva, Viviana; Ade, Peter A. R.; Aguirre, Paula; Amiri, Mandana; Appel, John William; Barrientos, L. Felipe; Battistelli, Elia S.; Bond, John R.; Brown, Ben; hide

    2011-01-01

    We present a new calibration method based on cross-correlations with the Wilkinson Microwave Anisotropy Probe (WMAP) and apply it to data from the Atacama Cosmology Telescope (ACT). ACT's observing strategy and mapmaking procedure allows an unbiased reconstruction of the modes in the maps over a wide range of multipoles. By directly matching the ACT maps to WMAP observations in the multipole range of 400 cosmological parameters estimated from the ACT power spectra. We also present a combined map based on ACT and WMAP data that has a high signal-to-noise ratio over a wide range of multipoles.

  10. Anisotropies of gravitational-wave standard sirens as a new cosmological probe without redshift information

    Science.gov (United States)

    Nishizawa, Atsushi; Namikawa, Toshiya; Taruya, Atsushi

    2016-03-01

    Gravitational waves (GWs) from compact binary stars at cosmological distances are promising and powerful cosmological probes, referred to as the GW standard sirens. With future GW detectors, we will be able to precisely measure source luminosity distances out to a redshift z 5. To extract cosmological information, previous studies using the GW standard sirens rely on source redshift information obtained through an extensive electromagnetic follow-up campaign. However, the redshift identification is typically time-consuming and rather challenging. Here we propose a novel method for cosmology with the GW standard sirens free from the redshift measurements. Utilizing the anisotropies of the number density and luminosity distances of compact binaries originated from the large-scale structure, we show that (i) this anisotropies can be measured even at very high-redshifts (z = 2), (ii) the expected constraints on the primordial non-Gaussianity with Einstein Telescope would be comparable to or even better than the other large-scale structure probes at the same epoch, (iii) the cross-correlation with other cosmological observations is found to have high-statistical significance. A.N. was supported by JSPS Postdoctoral Fellowships for Research Abroad No. 25-180.

  11. The Optical Design and Characterization of the Microwave Anisotropy Probe

    Science.gov (United States)

    Page, L.; Jackson, C.; Barnes, C.; Bennett, C.; Halpern, M.; Hinshaw, G.; Jarosik, N.; Kogut, A.; Limon, M.; Meyer, S. S.; Spergel, D. N.; Tucker, G. S.; Wilkinson, D. T.; Wollack, E.; Wright, E. L.

    2003-03-01

    The primary goal of the MAP satellite, now in orbit, is to make high-fidelity polarization-sensitive maps of the full sky in five frequency bands between 20 and 100 GHz. From these maps we will characterize the properties of the cosmic microwave background (CMB) anisotropy and Galactic and extragalactic emission on angular scales ranging from the effective beam size, less than 0.23d, to the full sky. MAP is a differential microwave radiometer. Two back-to-back shaped offset Gregorian telescopes feed two mirror symmetric arrays of 10 corrugated feeds. We describe the prelaunch design and characterization of the optical system, compare the optical models to the measurements, and consider multiple possible sources of systematic error.

  12. Probing the Intergalactic Magnetic Field with the Anisotropy of the Extragalactic Gamma-ray Background

    Science.gov (United States)

    Venters, T. M.; Pavlidou, V.

    2013-01-01

    The intergalactic magnetic field (IGMF) may leave an imprint on the angular anisotropy of the extragalactic gamma-ray background through its effect on electromagnetic cascades triggered by interactions between very high energy photons and the extragalactic background light. A strong IGMF will deflect secondary particles produced in these cascades and will thus tend to isotropize lower energy cascade photons, thereby inducing a modulation in the anisotropy energy spectrum of the gamma-ray background. Here we present a simple, proof-of-concept calculation of the magnitude of this effect and demonstrate that current Fermi data already seem to prefer nonnegligible IGMF values. The anisotropy energy spectrum of the Fermi gamma-ray background could thus be used as a probe of the IGMF strength.

  13. What have we learnt from Wilkinson microwave anisotropy probe?

    Indian Academy of Sciences (India)

    they were with the earlier observations. Accounting for known calibration uncer- tainties in the data, WMAP in large part agrees with earlier experiments like COBE,. Boomerang, MAXIMA, DASI and the VSA [2]. This is most clearly reflected in the fact that the best-fit cosmological model was not dramatically changed by the.

  14. Observations of the anisotropy of cosmic rays at TeV-PeV

    Science.gov (United States)

    BenZvi, S.

    2014-07-01

    During the past decade, multiple observatories have reported significant observations of the anisotropy of cosmic rays in the TeV energy band. The anisotropy has been observed at large scales and small scales in both the Northern and Southern Hemispheres. The source of the anisotropy is not well-understood, though both a galactic and a heliospheric origin have been suggested. We discuss recent observations of the shape and energy dependence of the anisotropy, with particular attention to measurements by the IceCube Neutrino Observatory in the Southern Hemisphere and the Milagro and High-Altitude Water Cherenkov (HAWC) observatories in the Northern Hemisphere.

  15. An Overview of Trajectory Design Operations for the Microwave Anisotropy Probe Mission

    Science.gov (United States)

    Mesarch, Michael A.; Kraft-Newman, Lauri; Cuevas, Osvaldo O.; Woodard, Mark; Bauer, Frank (Technical Monitor)

    2002-01-01

    The purpose of this paper is to document the results of the pre-launch trajectory design and the real-time operations for the Microwave Anisotropy Probe (MAP) mission, launched on June 30, 2001. Once MAP was successfully inserted into a highly elliptical phasing orbit, three perigee maneuvers and a final perigee correction maneuver were performed to tailor a lunar encounter on July 30, 2001. MAP achieved its final Lissajous orbit (0.5 deg. by 10.5 deg.) about the Sun-Earth/Moon L2 libration point via this lunar encounter. This paper will show the maneuvers that were designed to arrive at the mission orbit. A further discussion of how the MAP trajectory analysts altered the pre-launch phasing loop maneuvers as well as the lunar encounter to meet all mission constraints, including the constraint of zero lunar shadows is also included.

  16. Alignment Measurements of the Microwave Anisotropy Probe (MAP) Instrument in a Thermal/Vacuum Chamber

    Science.gov (United States)

    Hill, Michael D.; Herrera, Acey A.; Crane, J. Allen; Packard, Edward A.; Aviado, Carlos; Sampler, Henry P.

    2000-01-01

    The Microwave Anisotropy Probe (MAP) Observatory, scheduled for a fall 2000 launch, is designed to measure temperature fluctuations (anisotropy) and produce a high sensitivity and high spatial resolution (approximately 0.2 degree) map of the cosmic microwave background (CMB) radiation over the entire sky between 22 and 90 GHz. MAP utilizes back-to-back Gregorian telescopes to focus the microwave signals into 10 differential microwave receivers, via 20 feed horns. Proper alignment of the telescope reflectors and the feed horns at the operating temperature of 90 K is a critical element to ensure mission success. We describe the hardware and methods used to validate the displacement/deformation predictions of the reflectors and the microwave feed horns during thermal/vacuum testing of the reflectors and the microwave instrument. The smallest deformation predictions to be measured were on the order of +/- 0.030 inches (+/- 0.762 mm). Performance of these alignment measurements inside a thermal/vacuum chamber with conventional alignment equipment posed several limitations. The most troublesome limitation was the inability to send personnel into the chamber to perform the measurements during the test due to vacuum and the temperature extremes. The photogrammetry (PG) system was chosen to perform the measurements since it is a non- contact measurement system, the measurements can be made relatively quickly and accurately, and the photogrammetric camera can be operated remotely. The hardware and methods developed to perform the MAP alignment measurements using PG proved to be highly successful. The measurements met the desired requirements, for the metal structures enabling the desired distortions to be measured resolving deformations an order of magnitude smaller than the imposed requirements. Viable data were provided to the MAP Project for a full analysis of the on-orbit performance of the Instrument's microwave system.

  17. Geotail observations of temperature anisotropy of the two-component protons in the dusk plasma sheet

    Directory of Open Access Journals (Sweden)

    M. N. Nishino

    2007-03-01

    Full Text Available In search for clues towards the understanding of the cold plasma sheet formation under northward IMF, we study the temperature anisotropy of the two-component protons in the plasma sheet near the dusk low-latitude boundary observed by the Geotail spacecraft. The two-component protons result from mixing of the cold component from the solar wind and the hot component of the magnetospheric origin, and may be the most eloquent evidence for the transport process across the magnetopause. The cold component occasionally has a strong anisotropy in the dusk flank, and the sense of the anisotropy depends on the observed locations: the parallel temperature is enhanced in the tail flank while the perpendicular temperature is enhanced on the dayside. The hot component is nearly isotropic in the tail while the perpendicular temperature is enhanced on the dayside. We discuss possible mechanism that can lead to the observed temperature anisotropies.

  18. Consistency of Earth Radiation Budget Experiment bidirectional models and the observed anisotropy of reflected sunlight

    Science.gov (United States)

    Baldwin, Daniel G.; Coakley, James A., Jr.

    1991-01-01

    The anisotropy of the radiance field estimated from bidirectional models derived from Nimbus 7 ERB scanner data is compared with the anisotropy observed with the ERB Experiment (ERBE) scanner aboard the ERB satellite. The results of averaging over groups of 40 ERBE scanner scan lines for a period of a month revealed significant differences between the modeled and the observed anisotropy for given scene types and the sun-earth-satellite viewing geometries. By comparing the radiative fluxes derived using the observed anisotropy with those derived assuming isotropic reflection, it is concluded that a reasonable estimate for the maximum error due to the use of incorrect bidirectional models is a bias of about 4 percent for a typical 2.5 deg latitude-longitude monthly mean, and an rms error of 15 percent.

  19. The effect of crustal anisotropy on SKS splitting analysis - synthetic models and real data observations

    Science.gov (United States)

    Latifi, Koorosh; Kaviani, Ayoub; Rümpker, Georg; Mahmoodabadi, Meysam; Ghassemi, Mohammad R.; Sadidkhouy, Ahmad

    2018-02-01

    The contribution of crustal anisotropy to the observation of SKS splitting parameters is often assumed to be negligible. Based on synthetic models we show that the impact of crustal anisotropy on the SKS splitting parameters can be significant even in the case of moderate to weak anisotropy within the crust. In addition, real-data examples reveal that significant azimuthal variations in SKS splitting parameters can be caused by crustal anisotropy. Ps-splitting analysis of receiver functions can be used to infer the anisotropic parameters of the crust. These crustal splitting parameters may then be used to constrain the inversion of SKS apparent splitting parameters to infer the anisotropy of the mantle. The observation of SKS splitting for different azimuths is indispensable to verify the presence or absence of multiple layers of anisotropy beneath a seismic station. By combining SKS and RF observations in different azimuths at a station, we are able to uniquely decipher the anisotropic parameters of crust and upper mantle.

  20. Probing the interaction mechanisms between transmembrane peptides and the chaperonin GroEL with fluorescence anisotropy

    Science.gov (United States)

    Wang, Xiaoqiang; Chen, Han; Lu, Xinwei; Chi, Haixia; Li, Shixin; Huang, Fang

    2018-04-01

    Proper translocation, membrane insertion and folding are crucial biophysical steps in the biogenesis of functional transmembrane peptides/proteins (TMPs). ATP-dependent chaperonins are able to regulate each of these processes, but the underlying mechanisms remain unclear. In this work, interaction between the bacterial chaperonin GroEL and a synthetic fluorescent transmembrane peptide was investigated by fluorescence anisotropy. Binding of the peptide with GroEL resulted in increased fluorescence anisotropy and intensity. The dissociation constant and binding stoichiometry, as assessed by titration of the peptide with GroEL, were estimated to be 0.6 ± 0.2 μM and 2.96 ± 0.35, respectively. Complementary study with the single-ring version of GroEL confirmed the high-affinity peptide binding, and indicates that the two GroEL rings may function alternatively in binding the peptides. The co-chaperonin GroES was found to be effective at releasing the peptides initially bound to GroEL with the help of ATP. Moreover, our observation with the single-ring GroEL mutant demonstrated that during the encapsulation of GroEL by GroES, the bound peptides may either be confined in the cage thus formed, or escape outside. Competitive binding experiments indicated that the peptides studied interact with GroEL through the paired helices H and I on its apical domain. Our spectroscopic studies revealed some basic mechanisms of interaction between transmembrane peptides and GroEL, which would be instrumental for deciphering the chaperonin-mediated TMP biogenesis.

  1. Consistency of Earth Radiation Budget Experiment bidirectional models and the observed anisotropy of reflected sunlight

    Energy Technology Data Exchange (ETDEWEB)

    Baldwin, D.G. (Univ. of Colorado, Boulder (USA)); Coakley, J.A. (Oregon State Univ., Corvallis (USA))

    1991-03-20

    The Earth Radiation Budget Experiment (ERBE) uses bidirectional models to estimate radiative fluxes from observed radiances. The anisotropy of the radiance field derived from these models is compared with that observed with the ERBE scanner on the Earth Radiation Budget Satellite (ERBS). The bidirectional models used by ERBE were derived from NIMBUS 7 Earth radiation budget (ERB) scanner observations. Because of probable differences in the radiometric calibrations of the ERB and ERBE scanners and because of differences in their field of view sizes, the authors expect to find systematic differences of a few percent between the NIMBUS 7 ERB-derived radiation field anisotropy and the ERBS scanner-observed anisotropy. The differences expected are small compared with the variability of the anisotropy which arises from the variability in cloud cover allowed to occur within the individual scene types. By averaging over groups of 40 ERBE scanner scan lines (equivalent to an average over approximately 2,000 km) for a period of a month, they detect significant differences between the modeled and observed anisotropy for particular scene types and Sun-Earth-satellite viewing geometries. For a typical 2.5{degree} latitude-longitude region these differences give rise to a bias in the radiative flux that is at least 0.3% for the monthly mean and an rms error that is at least 4% for instantaneous observations. By comparing the fluxes derived using the observed anisotropy with those derived assuming isotropic reflection, they conclude that a reasonable estimate for the maximum error due to the use of incorrect bidirectional models is a bias of approximately 4% for a typical 2.5{degree} latitude-longitude, monthly mean and an rms error of 15%.

  2. How to probe transverse magnetic anisotropy of a single-molecule magnet by electronic transport?

    Science.gov (United States)

    Misiorny, M.; Burzuri, E.; Gaudenzi, R.; Park, K.; Leijnse, M.; Wegewijs, M.; Paaske, J.; Cornia, A.; van der Zant, H.

    We propose an approach for in-situ determination of the transverse magnetic anisotropy (TMA) of an individual molecule by electronic transport measurements, see Phys. Rev. B 91, 035442 (2015). We study a Fe4 single-molecule magnet (SMM) captured in a gateable junction, a unique tool for addressing the spin in different redox states of a molecule. We show that, due to mixing of the spin eigenstates of the SMM, the TMA significantly manifests itself in transport. We predict and experimentally observe the pronounced intensity modulation of the Coulomb peak amplitude with the magnetic field in the linear-response transport regime, from which the TMA parameter E can be estimated. Importantly, the method proposed here does not rely on the small induced tunnelling effects and, hence, works well at temperatures and electron tunnel broadenings by far exceeding the tunnel splittings and even E itself. We deduce that the TMA for a single Fe4 molecule captured in a junction is substantially larger than the bulk value. Work supported by the Polish Ministry of Science and Education as `Iuventus Plus' project (IP2014 030973) in years 2015-2016.

  3. Stable indications of relic gravitational waves in Wilkinson Microwave Anisotropy Probe data and forecasts for the Planck mission

    International Nuclear Information System (INIS)

    Zhao, W.; Baskaran, D.; Grishchuk, L. P.

    2009-01-01

    The relic gravitational waves are the cleanest probe of the violent times in the very early history of the Universe. They are expected to leave signatures in the observed cosmic microwave background anisotropies. We significantly improved our previous analysis [W. Zhao, D. Baskaran, and L. P. Grishchuk, Phys. Rev. D 79, 023002 (2009)] of the 5-year WMAP TT and TE data at lower multipoles l. This more general analysis returned essentially the same maximum likelihood result (unfortunately, surrounded by large remaining uncertainties): The relic gravitational waves are present and they are responsible for approximately 20% of the temperature quadrupole. We identify and discuss the reasons by which the contribution of gravitational waves can be overlooked in a data analysis. One of the reasons is a misleading reliance on data from very high multipoles l and another a too narrow understanding of the problem as the search for B modes of polarization, rather than the detection of relic gravitational waves with the help of all correlation functions. Our analysis of WMAP5 data has led to the identification of a whole family of models characterized by relatively high values of the likelihood function. Using the Fisher matrix formalism we formulated forecasts for Planck mission in the context of this family of models. We explore in detail various 'optimistic', 'pessimistic', and 'dream case' scenarios. We show that in some circumstances the B-mode detection may be very inconclusive, at the level of signal-to-noise ratio S/N=1.75, whereas a smarter data analysis can reveal the same gravitational wave signal at S/N=6.48. The final result is encouraging. Even under unfavorable conditions in terms of instrumental noises and foregrounds, the relic gravitational waves, if they are characterized by the maximum likelihood parameters that we found from WMAP5 data, will be detected by Planck at the level S/N=3.65.

  4. Detecting Population III Stars through Observations of Near-Infrared Cosmic Infrared Background Anisotropies

    Science.gov (United States)

    Kashlinsky, A.; Arendt, R.; Gardner, Jonathan P.; Mather, John C.; Moseley, S. Harvey

    2004-06-01

    Following the successful mapping of the last scattering surface by the Wilkinson Microwave Anisotropy Probe (WMAP) and balloon experiments, the epoch of the first stars, when Population III stars formed, is emerging as the next cosmological frontier. It is not clear what these stars' properties were, when they formed, or how long their era lasted before leading to the stars and galaxies we see today. We show that these questions can be answered with the current and future measurements of the near-IR cosmic infrared background (CIB). Theoretical arguments suggest that Population III stars were very massive and short-lived stars that formed at z~10-20 at rare peaks of the density field in the cold dark matter universe. Because Population III stars probably formed individually in small minihalos, they are not directly accessible to current telescopic studies. We show that these stars left a strong and measurable signature via their contribution to the CIB anisotropies for a wide range of their formation scenarios. The excess in the recently measured near-IR CIB anisotropies over that from normal galaxies can be explained by contribution from early Population III stars. These results imply that Population III were indeed very massive stars and that their epoch started at z~20 and lasted past zfuture space-based missions.

  5. Direct Observation of Magnetocrystalline Anisotropy Tuning Magnetization Configurations in Uniaxial Magnetic Nanomaterials.

    Science.gov (United States)

    Zhu, Shimeng; Fu, Jiecai; Li, Hongli; Zhu, Liu; Hu, Yang; Xia, Weixing; Zhang, Xixiang; Peng, Yong; Zhang, Junli

    2018-03-26

    Discovering the effect of magnetic anisotropy on the magnetization configurations of magnetic nanomaterials is essential and significant for not only enriching the fundamental knowledge of magnetics but also facilitating the designs of desired magnetic nanostructures for diverse technological applications, such as data storage devices, spintronic devices, and magnetic nanosensors. Herein, we present a direct observation of magnetocrystalline anisotropy tuning magnetization configurations in uniaxial magnetic nanomaterials with hexagonal structure by means of three modeled samples. The magnetic configuration in polycrystalline BaFe 12 O 19 nanoslice is a curling structure, revealing that the effect of magnetocrystalline anisotropy in uniaxial magnetic nanomaterials can be broken by forming an amorphous structure or polycrystalline structure with tiny grains. Both single crystalline BaFe 12 O 19 nanoslice and individual particles of single-particle-chain BaFe 12 O 19 nanowire appear in a single domain state, revealing a dominant role of magnetocrystalline anisotropy in the magnetization configuration of uniaxial magnetic nanomaterials. These observations are further verified by micromagnetic computational simulations.

  6. Direct Observation of Magnetocrystalline Anisotropy Tuning Magnetization Configurations in Uniaxial Magnetic Nanomaterials

    KAUST Repository

    Zhu, Shimeng

    2018-03-20

    Discovering the effect of magnetic anisotropy on the magnetization configurations of magnetic nanomaterials is essential and significant for not only enriching the fundamental knowledge of magnetics but also facilitating the designs of desired magnetic nanostructures for diverse technological applications, such as data storage devices, spintronic devices, and magnetic nanosensors. Herein, we present a direct observation of magnetocrystalline anisotropy tuning magnetization configurations in uniaxial magnetic nanomaterials with hexagonal structure by means of three modeled samples. The magnetic configuration in polycrystalline BaFe12O19 nanoslice is a curling structure, revealing that the effect of magnetocrystalline anisotropy in uniaxial magnetic nanomaterials can be broken by forming an amorphous structure or polycrystalline structure with tiny grains. Both single crystalline BaFe12O19 nanoslice and individual particles of single-particle-chain BaFe12O19 nanowire appear in a single domain state, revealing a dominant role of magnetocrystalline anisotropy in the magnetization configuration of uniaxial magnetic nanomaterials. These observations are further verified by micromagnetic computational simulations.

  7. Inner-core shear-wave anisotropy and texture from an observation of PKJKP waves.

    Science.gov (United States)

    Wookey, James; Helffrich, George

    2008-08-14

    Since the discovery of the Earth's core a century ago, and the subsequent discovery of a solid inner core (postulated to have formed by the freezing of iron) seismologists have striven to understand this most remote part of the deep Earth. The most direct evidence for a solid inner core would be the observation of shear-mode body waves that traverse it, but these phases are extremely difficult to observe. Two reported observations in short-period data have proved controversial. Arguably more successful have been studies of longer-period data, but such averaging limits the usefulness of the observations to reported sightings. We present two observations of an inner-core shear-wave phase at higher frequencies in stacked data from the Japanese High-Sensitivity Array, Hi-Net. From an analysis of timing, amplitude and waveform of the 'PKJKP' phase we derive constraints on inner-core compressional-wave velocity and shear attenuation at about 0.3 Hz which differ from standard isotropic core models. We can explain waveform features and can partially reconcile the otherwise large differences between core wavespeed and attenuation models that our observations apparently suggest if we invoke shear-wave anisotropy in the inner core. A simple model of an inner core composed of hexagonal close-packed iron with its c axis aligned perpendicular to the rotation axis yields anisotropy that is compatible with both the shear-wave anisotropy that we observe and the well-established 3 per cent compressional-wave anisotropy.

  8. Observations of solar flare particle anisotropies from 1.0 to 4.7 AU

    International Nuclear Information System (INIS)

    McCarthy, J.J.

    1977-01-01

    The anisotropy of protons produced by solar flare particle events has been studied using the University of Chicago Charged Particle Instruement Main Telescope on the Pioneer 10 and 11 spacecraft. The observations were made during 1972 ad 1973 and covered a range of solar radial distances of 1.0 to 4.7 AU. The Pioneer spacecraft rotate at a rate of about 5 RPM around a spin axis which lies in the ecliptic plane. The Main Telescope scans the sky at an angle of 70 0 to the spin axis. Counting rates and angular information are recorded and rates for each of eight 45 0 -sectors are computed in ground processing. The anisotropy amplitude, delta, and phase,phi, is computed by fitting the function C 0 (1 + delta cos(theta-phei)) to the eight sectored rates (C 0 is the average rate). The resulting anisotropy amplitude is corrected for telemetry-induced distortions. Using a model of cosmic ray diffusion developed by Parker (1963) and Krimigis (1965) to analyze the anisotropy observations, it has been determined that the diffusion coefficient of 3 to 10 MeV protons travelling parallel to the magnetic field is: K 11 (r) = (9.78 +- 2.3) x 10 21 r 1 01 +- 0 24 cm 2 /sec where r is the radial distance in AU. The corresponding 3-dimensional radial diffusion coefficient is K/sub r 3 /(r) = (1.35 +- 0.32) x 10 21 r -0 63 +- 0 24 cm 2 /sec. Comparison of these numbers with other experimental results is made, and theoretical implications are discussed. The dependence of the anisotropy on energy is investigated and is found to be the proportional 1/v, as predicted by diffusion theory, near the times of maximum flux in the flare, but at earlier and later times, it deviates from this dependence

  9. Solar wind proton temperature anisotropy: Linear theory and WIND/SWE observations

    Czech Academy of Sciences Publication Activity Database

    Hellinger, Petr; Trávníček, Pavel; Kasper, J. C.; Lazarus, A. J.

    2006-01-01

    Roč. 33, č. 9 (2006), L09101/1-L09101/4 ISSN 0094-8276 R&D Projects: GA AV ČR(CZ) IAA3042403 Grant - others:ESA(XE) PECS 98024; NASA (US) NAG-10915 Institutional research plan: CEZ:AV0Z30420517 Keywords : proton temperature anisotropy * solar wind * in situ observations Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 2.602, year: 2006

  10. Pressure tuning of anisotropy barrier in Fe8 SMMs probed using high frequency EPR

    Science.gov (United States)

    Thirunavukkuarasu, Komalavalli; Beedle, Christopher; Tozer, Stanley; Hill, Stephen

    2014-03-01

    Single-molecule magnets (SMMs) are spin systems with large spin ground state where quantum phenomena such as tunneling of magnetization via a considerable anisotropy barrier manifest. One such SMM that has been extensively studied is [Fe8O2(OH)12(tacn)6]Br8.9H2O, also known as Fe8, with a giant spin ground state of S=10. The eight Fe atoms bridged by the ligands form a butterfly structure where six Fe atoms have spins up and two spins down in the simplest model. This structure in fact gives rise to geometrical spin frustration effects within the cluster. By varying the interaction between the spins, manipulation of quantum tunneling in SMMs may be achieved. Typically, the manipulation of spin interactions is realized using chemical methods. As an alternative approach, we employ high pressure to induce changes in the ligand-field environment of the Fe atoms. In this presentation, the pressure-dependent changes in the anisotropy barrier in single crystal Fe8 SMMs investigated by high frequency electron paramagnetic resonance measurements will be discussed.

  11. Cosmological observables, IR growth of fluctuations, and scale-dependent anisotropies

    DEFF Research Database (Denmark)

    B. Giddings, Steven; Sloth, Martin Snoager

    2011-01-01

    We extend semiclassical methods in inflationary cosmology that capture leading IR corrections to correlators. Such large IR effects can be absorbed into a coordinate change when examining sufficiently local observables, but not when comparing observations at large separation in scales, such as seen...... by a late-time observer. The analysis is facilitated by definition of a scale-dependent metric and physical momentum. These assist definition of "IR-safe" observables seen by a post-inflationary observer, which are contrasted to those based on the local geometry of the reheating surface....... For such observables, the observer's horizon provides an effective IR cutoff. IR growth contributes to enhanced statistical inhomogeneities/anisotropies at short scales, observation of which by a present day observer might be sought in 21 cm measurements. Such IR corrections are argued to grow large for a very late...

  12. Detection of zero anisotropy at 5.2 AU during the November 1998 solar particle event: Ulysses Anisotropy Telescopes observations

    Directory of Open Access Journals (Sweden)

    S. Dalla

    Full Text Available For the first time during the mission, the Anisotropy Telescopes instrument on board the Ulysses spacecraft measured constant zero anisotropy of protons in the 1.3-2.2 MeV energy range, for a period lasting more than three days. This measurement was made during the energetic particle event taking place at Ulysses between 25 November and 15 December 1998, an event characterised by constant high proton fluxes within a region delimited by two interplanetary forward shocks, at a distance of 5.2 AU from the Sun and heliographic latitude of 17°S. We present the ATs results for this event and discuss their possible interpretation and their relevance to the issue of intercalibration of the two telescopes.

    Key words: Interplanetary physics (energetic particles - Solar physics, astrophysics and astronomy (energetic particles - Space plasma physics (instruments and techniques

  13. Direct observation of in-plane anisotropy of the superconducting critical current density in Ba (Fe1-xCox) 2As2 crystals

    Science.gov (United States)

    Hecher, J.; Ishida, S.; Song, D.; Ogino, H.; Iyo, A.; Eisaki, H.; Nakajima, M.; Kagerbauer, D.; Eisterer, M.

    2018-01-01

    The phase diagram of iron-based superconductors exhibits structural transitions, electronic nematicity, and magnetic ordering, which are often accompanied by an electronic in-plane anisotropy and a sharp maximum of the superconducting critical current density (Jc) near the phase boundary of the tetragonal and the antiferromagnetic-orthorhombic phase. We utilized scanning Hall-probe microscopy to visualize the Jc of twinned and detwinned Ba (Fe1-xCox) 2As2 (x =5 %-8 % ) crystals to compare the electronic normal state properties with superconducting properties. We find that the electronic in-plane anisotropy continues into the superconducting state. The observed correlation between the electronic and the Jc anisotropy agrees qualitatively with basic models, however, the Jc anisotropy is larger than predicted from the resistivity data. Furthermore, our measurements show that the maximum of Jc at the phase boundary does not vanish when the crystals are detwinned. This shows that twin boundaries are not responsible for the large Jc, suggesting an exotic pinning mechanism.

  14. Anisotropy of the structure factor of magnetic fluids under a field probed by small-angle neutron scattering

    International Nuclear Information System (INIS)

    Gazeau, F.; Bacri, J.-C.; Perzynski, R.; Dubois, E.; Boue, F.; Cebers, A.

    2002-01-01

    Small-angle neutron scattering is used to measure the two-dimensional diffraction pattern of a monophasic magnetic colloid, under an applied magnetic field. This dipolar system presents in zero field a fluidlike structure. It is well characterized by an interaction parameter K T 0 proportional to the second virial coefficient, which is here positive, expressing a repulsion of characteristic length κ 0 -1 . Under the field a strong anisotropy is observed at the lowest q vectors. The length κ 0 -1 remains isotropic, but the interaction parameter K T becomes anisotropic due to the long-range dipolar interaction. However, the system remains stable, the interaction being repulsive in all directions. Thus No.No.we do not observe any chaining of the nanoparticles under magnetic field. On the contrary, the revealed structure of our anisotropic colloid is a lowering of the concentration fluctuations along the field while the fluidlike structure, observed without field, is roughly preserved perpendicularly to the field. It expresses a strong anisotropy of the Brownian motion of the nanoparticles in the solution under applied field

  15. Anisotropy of the structure factor of magnetic fluids under a field probed by small-angle neutron scattering.

    Science.gov (United States)

    Gazeau, F; Dubois, E; Bacri, J C; Boué, F; Cebers, A; Perzynski, R

    2002-03-01

    Small-angle neutron scattering is used to measure the two-dimensional diffraction pattern of a monophasic magnetic colloid, under an applied magnetic field. This dipolar system presents in zero field a fluidlike structure. It is well characterized by an interaction parameter K(0)(T) proportional to the second virial coefficient, which is here positive, expressing a repulsion of characteristic length kappa-10. Under the field a strong anisotropy is observed at the lowest q vectors. The length kappa-10 remains isotropic, but the interaction parameter K(T) becomes anisotropic due to the long-range dipolar interaction. However, the system remains stable, the interaction being repulsive in all directions. Thus we do not observe any chaining of the nanoparticles under magnetic field. On the contrary, the revealed structure of our anisotropic colloid is a lowering of the concentration fluctuations along the field while the fluidlike structure, observed without field, is roughly preserved perpendicularly to the field. It expresses a strong anisotropy of the Brownian motion of the nanoparticles in the solution under applied field.

  16. Bidirectional electron anisotropies in the distant tail: ISEE-3 observations of polar rain

    International Nuclear Information System (INIS)

    Baker, D.N.; Bame, S.J.; Feldman, W.C.; Gosling, J.T.; Zwickl, R.D.; Slavin, J.A.; Smith, E.J.

    1985-01-01

    A detailed observational treatment of bidirectional electrons (50 approx.500 eV) in the distant magnetotail (r greater than or equal to 100 R/sub E/) is presented. It is found that electrons in this energy range commonly exhibit strong, field-aligned anisotropies in the tail lobes. Because of large tail motions, the ISEE-3 data provide extensive sampling of both the north and south lobes in rapid succession, demonstrating directly the strong asymmetries that exist between the north and south lobes at any one time. The bidirectional fluxes are found to occur predominantly in the lobe directly connected to the sunward IMF in the open magnetosphere model (north lobe for away sectors and south lobe for toward sectors). Electron anisotropy and magnetic field data are presented which show the transition from unidirectional (sheath) electron populations to bidirectional (lobe) populations. Taken together, the present evidence suggests that the bidirectional electrons that we observe in the distant tail are closely related to the polar rain electrons observed previously at lower altitudes. Furthermore, these data provide strong evidence that the distant tail is comprised largely of open magnetic field lines in contradistinction to some recently advanced models

  17. Testing the Interacting Dark Energy Model with Cosmic Microwave Background Anisotropy and Observational Hubble Data

    Directory of Open Access Journals (Sweden)

    Weiqiang Yang

    2017-07-01

    Full Text Available The coupling between dark energy and dark matter provides a possible approach to mitigate the coincidence problem of the cosmological standard model. In this paper, we assumed the interacting term was related to the Hubble parameter, energy density of dark energy, and equation of state of dark energy. The interaction rate between dark energy and dark matter was a constant parameter, which was, Q = 3 H ξ ( 1 + w x ρ x . Based on the Markov chain Monte Carlo method, we made a global fitting on the interacting dark energy model from Planck 2015 cosmic microwave background anisotropy and observational Hubble data. We found that the observational data sets slightly favored a small interaction rate between dark energy and dark matter; however, there was not obvious evidence of interaction at the 1 σ level.

  18. Inner Core Anisotropy: Can Seismic Observations be Reconciled with Ab Initio Calculations of Elasticity?

    Science.gov (United States)

    Song, X.; Jordan, T. H.

    2016-12-01

    Body-wave and normal-mode observations have revealed an inner-core structure that is radially layered, axially anisotropic, and hemispherically asymmetric. Previous theoretical studies have examined the consistency of these features with the elasticity of iron crystals thought to dominate inner-core composition, but a fully consistent model has been elusive. Here we compare the seismic observation with effective-medium models derived from ab initio calculations of the elasticity tensors for hcp-Fe and bcc-Fe. Our estimates are based on Jordan's (GJI, 2015) effective medium theory, which is derived from a self-consistent, second-order Born approximation. The theory provides closed-form expressions for the effective elastic parameters of 3D anisotropic, heterogeneous media in which the local anisotropy is a constant hexagonal stiffness tensor C stochastically oriented about a constant symmetry axis \\hat{s} and the statistics of the small-scale heterogeneities are transversely isotropic in the plane perpendicular to \\hat{s}. The stochastic model is then described by a dimensionless "aspect ratio of the heterogeneity", 0 ≤ η body-wave observations, then these hcp-Fe models predict that the fast polarization of the S waves is in the plane perpendicular to \\hat{s}, which disagrees with most normal-mode models. We have attempted to resolve this discrepancy by examining alternative hcp-Fe models, including radially anisotropic distributions of stochastic anisotropy and heterogeneity (i.e., where \\hat{s} = \\hat{r}), as well as bcc-Fe models. Our calculations constrain the form of C needed to satisfy the seismological inferences.

  19. Spectra and anisotropy of magnetic fluctuations in the Earth's magnetosheath: Cluster observations

    Directory of Open Access Journals (Sweden)

    O. Alexandrova

    2008-11-01

    Full Text Available We investigate the spectral shape, the anisotropy of the wave vector distributions and the anisotropy of the amplitudes of the magnetic fluctuations in the Earth's magnetosheath within a broad range of frequencies [10−3, 10] Hz which corresponds to spatial scales from ~10 to 105 km. We present the first observations of a Kolmogorov-like inertial range of Alfvénic fluctuations δB2}~f−5/3 in the magnetosheath flanks, below the ion cyclotron frequency fci. In the vicinity of fci, a spectral break is observed, like in solar wind turbulence. Above the break, the energy of compressive and Alfvénic fluctuations generally follows a power law with a spectral index between −3 and −2. Concerning the anisotropy of the wave vector distribution, we observe a clear change in its nature in the vicinity of ion characteristic scales: if at MHD scales there is no evidence for a dominance of a slab (kł>>k or 2-D (k>>kł turbulence, above the spectral break, (f>fci, kcpi>1 the 2-D turbulence dominates. This 2-D turbulence is observed in six selected one-hour intervals among which the average ion β varies from 0.8 to 10. It is observed for both the transverse and compressive magnetic fluctuations, independently on the presence of linearly unstable modes at low frequencies or Alfvén vortices at the spectral break. We then analyse the anisotropy of the magnetic fluctuations in a time dependent reference frame based on the field B and the flow velocity V directions. Within the range of the 2-D turbulence, at scales [1,30]kcpi, and for any β we find that the magnetic fluctuations at a given frequency in the plane perpendicular to B have more energy along the

  20. Mechanical Anisotropy and Pressure Induced Structural Changes in Piroxicam Crystals Probed by In Situ Indentation and Raman Spectroscopy

    Science.gov (United States)

    Manimunda, Praveena; Hintsala, Eric; Asif, Syed; Mishra, Manish Kumar

    2017-01-01

    The ability to correlate mechanical and chemical characterization techniques in real time is both lacking and powerful tool for gaining insights into material behavior. This is demonstrated through use of a novel nanoindentation device equipped with Raman spectroscopy to explore the deformation-induced structural changes in piroxicam crystals. Mechanical anisotropy was observed in two major faces ( 0bar{1}1 ) and (011), which are correlated to changes in the interlayer interaction from in situ Raman spectra recorded during indentation. The results of this study demonstrate the considerable potential of an in situ Raman nanoindentation instrument for studying a variety of topics, including stress-induced phase transformation mechanisms, mechanochemistry, and solid state reactivity under mechanical forces that occur in molecular and pharmaceutical solids.

  1. Observation of cross-shaped anisotropy in spin-resolved small-angle neutron scattering

    Science.gov (United States)

    Michels, Andreas; Honecker, Dirk; Döbrich, Frank; Dewhurst, Charles D.; Suzuki, Kiyonori; Heinemann, André

    2012-05-01

    We report the results of spin-resolved small-angle neutron scattering (SANS) experiments on the two-phase nanocrystalline alloy NANOPERM. At a saturating applied magnetic field of 1.27T we observe a cross-shaped angular anisotropy in the non-spin-flip SANS cross section Σ++. This feature—for this class of materials only visible at saturation in Σ++—is attributed to the specific ratio of nuclear to magnetic scattering being smaller than unity. Analysis of the non-spin-flip and spin-flip cross sections provides the nuclear and magnetic SANS and allows us to estimate the magnitude of the respective scattering-length density contrast at the interphase between the nanoparticles and the amorphous magnetic matrix.

  2. ARRAY FOR MICROWAVE BACKGROUND ANISOTROPY: OBSERVATIONS, DATA ANALYSIS, AND RESULTS FOR SUNYAEV-ZEL'DOVICH EFFECTS

    International Nuclear Information System (INIS)

    Wu, J.-H.P.; Huang, C.-W.L.; Liao, Y.-W.; Lin, K.-Y.; Wang, F.-C.; Chiueh Tzihong; Ho, Paul T. P.; Koch, Patrick M.; Liu, G.-C.; Molnar, Sandor M.; Nishioka, Hiroaki; Altamirano, Pablo; Chang, C.-H.; Chang, S.-H.; Chang, S.-W.; Chen, M.-T.; Han, C.-C.; Huang, Y.-D.; Umetsu, Keiichi; Birkinshaw, Mark

    2009-01-01

    We present observations, analysis, and results for the first-year operation of Array for Microwave Background Anisotropy (AMiBA), an interferometric experiment designed to study cosmology via the measurement of cosmic microwave background (CMB). AMiBA is the first CMB interferometer operating at 3 mm to have reported successful results, currently with seven close-packed antennas of 60 cm diameter giving a synthesized resolution of around 6'. During 2007, AMiBA detected the Sunyaev-Zel'dovich effects (SZEs) of six galaxy clusters at redshift 0.091 ≤ z ≤ 0.322. An observing strategy with on-off-source switching is used to minimize the effects from electronic offset and ground pickup. Planets were used to test the observational capability of AMiBA and to calibrate the conversion from correlator time-lag data to visibilities. The detailed formalism for data analysis is given. We summarize our early tests including observations of planets and quasars, and present images, visibility profiles, the estimated central coordinates, sizes, and SZE amplitudes of the galaxy clusters. Scientific implications are summarized. We also discuss possible systematic effects in the results.

  3. COMET 22P/KOPFF: DUST ENVIRONMENT AND GRAIN EJECTION ANISOTROPY FROM VISIBLE AND INFRARED OBSERVATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Moreno, Fernando; Pozuelos, Francisco; Aceituno, Francisco; Casanova, Victor; Sota, Alfredo [Instituto de Astrofisica de Andalucia, CSIC, Glorieta de la Astronomia s/n, 18008 Granada (Spain); Castellano, Julio; Reina, Esteban, E-mail: fernando@iaa.es [Amateur Association Cometas-Obs (Spain)

    2012-06-20

    We present optical observations and Monte Carlo models of the dust coma, tail, and trail structures of the comet 22P/Kopff during the 2002 and 2009 apparitions. Dust loss rates, ejection velocities, and power-law size distribution functions are derived as functions of the heliocentric distance using pre- and post-perihelion imaging observations during both apparitions. The 2009 post-perihelion images can be accurately fitted by an isotropic ejection model. On the other hand, strong dust ejection anisotropies are required to fit the near-coma regions at large heliocentric distances (both inbound at r{sub h} = 2.5 AU and outbound at r{sub h} = 2.6 AU) for the 2002 apparition. These asymmetries are compatible with a scenario where dust ejection is mostly seasonally driven, coming mainly from regions near subsolar latitudes at far heliocentric distances inbound and outbound. At intermediate to near-perihelion heliocentric distances, the outgassing would affect much more extended latitude regions, the emission becoming almost isotropic near perihelion. We derived a maximum dust production rate of 260 kg s{sup -1} at perihelion, and an averaged production rate over one orbit of 40 kg s{sup -1}. An enhanced emission rate, also accompanied by a large ejection velocity, is predicted at r{sub h} > 2.5 pre-perihelion. The model has also been extended to the thermal infrared in order to be applied to available trail observations of this comet taken with IRAS and Infrared Space Observatory spacecrafts. The modeled trail intensities are in good agreement with those observations, which is remarkable taking into account that those data are sensitive to dust ejection patterns corresponding to several orbits before the 2002 and 2009 apparitions.

  4. Generation and effects of EMIC waves observed by the Van Allen Probes on 18 March 2013

    Science.gov (United States)

    Zhang, J.; Saikin, A.; Gamayunov, K. V.; Spence, H. E.; Larsen, B.; Geoffrey, R.; Smith, C. W.; Torbert, R. B.; Kurth, W. S.; Kletzing, C.

    2015-12-01

    Electromagnetic ion cyclotron (EMIC) waves play a crucial role in particle dynamics in the Earth's magnetosphere. The free energy for EMIC wave generation is usually provided by the temperature anisotropy of the energetic ring current ions. EMIC waves can in turn cause particle energization and losses through resonant wave-particle interactions. Using measurements from the Van Allen Probes, we perform a case study of EMIC waves and associated plasma conditions observed on 18 March 2013. From 0204 to 0211 UT, the Van Allen Probe-B detected He+-band EMIC wave activity in the post-midnight sector (MLT=4.6-4.9) at very low L-shells (L=2.6-2.9). The event occurred right outside the inward-pushed plasmapause in the early recovery phase of an intense geomagnetic storm - min. Dst = -132 nT at 2100 UT on 17 March 2013. During this event, the fluxes of energetic (> 1 keV), anisotropic O+ dominate both the H+ and He+ fluxes in this energy range. Meanwhile, O+ fluxes at low energies (magnetic field. EMIC wave growth rates are also calculated to evaluate the role of loss-cone distributed ring current ions in the EMIC wave generation.

  5. Observation of an Anisotropy in the Galactic Cosmic Ray Arrival Direction at 400 TeV with IceCube

    Science.gov (United States)

    Abbasi, R.; Abdou, Y.; Abu-Zayyad, T.; Ackermann, M.; Adams, J.; Aguilar, J. A.; Ahlers, M.; Allen, M. M.; Altmann, D.; Andeen, K.; hide

    2012-01-01

    In this paper we report the first observation in the Southern hemisphere of an energy dependence in the Galactic cosmic ray anisotropy up to a few hundred TeV. This measurement was performed using cosmic ray induced muons recorded by the partially deployed IceCube observatory between May 2009 and May 2010. The data include a total of 33 x 10(exp 9) muon events with a median angular resolution of approx. 3 degrees. A sky map of the relative intensity in arrival direction over the Southern celestial sky is presented for cosmic ray median energies of 20 and 400 TeV. The same large-scale anisotropy observed at median energies around 20 TeV is not present at 400 TeV. Instead, the high energy skymap shows a different anisotropy structure including a deficit with a post-trial significance of -6.3 sigma. This anisotropy reveals a new feature of the Galactic cosmic ray distribution, which must be incorporated into theories of the origin and propagation of cosmic rays.

  6. Observation of Anisotropy in the Galactic Cosmic Ray Arrival Directions at 400 TEV With IceCube

    Science.gov (United States)

    Abbasi, R.; Abdou, Y.; Abu-Zayyad, T.; Ackermann, M.; Adams, J.; Aguilar, J. A.; Ahlers, M.; Allen, M. M.; Altmann, D.; Andeen, K.; hide

    2011-01-01

    In this paper we report the first observation in the Southern hemisphere of an energy dependence in the Galactic cosmic ray anisotropy up to a few hundred TeV. This measurement was performed using cosmic ray induced muons recorded by the partially deployed IceCube observatory between May 2009 and May 2010. The data include a total of 33x l0(epx 9) muon events with a median angular resolution of approx 3 degrees. A sky map of the relative intensity in arrival direction over the Southern celestial sky is presented for cosmic ray median energies of 20 and 400 Te V. The same large-scale anisotropy observed at median energies around 20 TeV is not present at 400 TeV. Instead, the high energy skymap shows a different anisotropy structure including a deficit with a post-trial significance of -6.30 sigma. This anisotropy reveals a new feature of the Galactic cosmic ray distribution, which must be incorporated into theories of the origin and propagation of cosmic rays.

  7. EMIC waves covering wide L shells: MMS and Van Allen Probes observations

    Science.gov (United States)

    Yu, Xiongdong; Yuan, Zhigang; Huang, Shiyong; Wang, Dedong; Li, Haimeng; Qiao, Zheng; Yao, Fei

    2017-07-01

    During 04:45:00-08:15:00 UT on 13 September in 2015, a case of Electromagnetic ion cyclotron (EMIC) waves covering wide L shells (L = 3.6-9.4), observed by the Magnotospheric Multiscale 1 (MMS1) are reported. During the same time interval, EMIC waves observed by Van Allen Probes A (VAP-A) only occurred just outside the plasmapause. As the Van Allen Probes moved outside into a more tenuous plasma region, no intense waves were observed. Combined observations of MMS1 and VAP-A suggest that in the terrestrial magnetosphere, an appropriately dense background plasma would make contributions to the growth of EMIC waves in lower L shells, while the ion anisotropy, driven by magnetospheric compression, might play an important role in the excitation of EMIC waves in higher L shells. These EMIC waves are observed over wide L shells after three continuous magnetic storms, which suggests that these waves might obtain their free energy from those energetic ions injected during storm times. These EMIC waves should be included in radiation belt modeling, especially during continuous magnetic storms. Moreover, two-band structures separated in frequencies by local He2+ gyrofrequencies were observed in large L shells (L > 6), implying sufficiently rich solar wind origin He2+ likely in the outer ring current. It is suggested that multiband-structured EMIC waves can be used to trace the coupling between solar wind and the magnetosphere.tract type="synopsis">le type="main">Plain Language SummaryThe spatial distribution of EMIC waves is an opening question. With combined observations of MMS and Van Allen Probes, this paper has reported EMIC waves covering wide L shells. Moreover, two-band structures separated in frequencies by local He2+ gyrofrequencies were observed in large L shells (L > 6), implying sufficiently rich solar wind origin He2+ likely in the outer ring current. The result is helpful to revealing the spatial distribution and role of He2+ in excitation of EMIC waves.

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

    Science.gov (United States)

    Moghaddam, S. Mortazavi; Bahmanabadi, M.

    2018-03-01

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

  9. Observations of Large Scale Sidereal Anisotropy in 1 and 11 TeV cosmic rays from the MINOS experiment

    Energy Technology Data Exchange (ETDEWEB)

    de Jong, J.K.

    2012-01-01

    The MINOS Near and Far Detectors are two large, functionally-identical, steel-scintillating sampling calorimeters located at depths of 220 mwe and 2100 mwe respectively. The detectors observe the muon component of hadronic showers produced from cosmic ray interactions with nuclei in the earth's atmosphere. From the arrival direction of these muons, the anisotropy in arrival direction of the cosmic ray primaries can be determined. The MINOS Near and Far Detector have observed anisotropy on the order of 0.1% at 1 and 11 TeV respectively. The amplitude and phase of the first harmonic at 1 TeV are 8.2 {+-} 1.7(stat.) x 10{sup -4} and (8.9 {+-} 12.1(stat.)){sup o}, and at 11 TeV are 3.8 {+-} 0.5(stat.) x 10{sup -4} and (27.2 {+-} 7.2(stat.)){sup o}.

  10. Probing black holes at low redshift using LISA EMRI observations

    International Nuclear Information System (INIS)

    Gair, Jonathan R

    2009-01-01

    One of the most exciting potential sources of gravitational waves for the Laser Interferometer Space Antenna (LISA) are the inspirals of approximately solar mass compact objects into massive black holes in the centres of galaxies-extreme mass ratio inspirals (EMRIs). LISA should observe between a few tens and a few hundred EMRIs over the mission lifetime, mostly at low redshifts (z∼< 1). Each observation will provide a measurement of the parameters of the host system to unprecendented precision. LISA EMRI observations will thus offer a new and unique way to probe black holes at low redshift. In this paper we provide a description of the population of EMRI events that LISA is likely to observe, and describe how the numbers of events vary with changes in the underlying assumptions about the black hole population. We also provide fitting functions that characterize LISA's ability to detect EMRIs and which will allow LISA event rates to be computed for arbitrary population models. We finish with a discussion of an ongoing programme that will use these results to assess what constraints LISA observations could place on galaxy evolution models.

  11. SEVEN-YEAR WILKINSON MICROWAVE ANISOTROPY PROBE (WMAP ) OBSERVATIONS: COSMOLOGICAL INTERPRETATION

    International Nuclear Information System (INIS)

    Komatsu, E.; Smith, K. M.; Spergel, D. N.; Dunkley, J.; Bennett, C. L.; Gold, B.; Larson, D.; Hinshaw, G.; Kogut, A.; Wollack, E.; Jarosik, N.; Page, L.; Nolta, M. R.; Halpern, M.; Hill, R. S.; Odegard, N.; Weiland, J. L.; Limon, M.; Meyer, S. S.; Tucker, G. S.

    2011-01-01

    The combination of seven-year data from WMAP and improved astrophysical data rigorously tests the standard cosmological model and places new constraints on its basic parameters and extensions. By combining the WMAP data with the latest distance measurements from the baryon acoustic oscillations (BAO) in the distribution of galaxies and the Hubble constant (H 0 ) measurement, we determine the parameters of the simplest six-parameter ΛCDM model. The power-law index of the primordial power spectrum is n s = 0.968 ± 0.012 (68% CL) for this data combination, a measurement that excludes the Harrison-Zel'dovich-Peebles spectrum by 99.5% CL. The other parameters, including those beyond the minimal set, are also consistent with, and improved from, the five-year results. We find no convincing deviations from the minimal model. The seven-year temperature power spectrum gives a better determination of the third acoustic peak, which results in a better determination of the redshift of the matter-radiation equality epoch. Notable examples of improved parameters are the total mass of neutrinos, ΣM ν eff = 4.34 +0.86 -0.88 (68% CL), which benefit from better determinations of the third peak and H 0 . The limit on a constant dark energy equation of state parameter from WMAP+BAO+H 0 , without high-redshift Type Ia supernovae, is w = -1.10 ± 0.14 (68% CL). We detect the effect of primordial helium on the temperature power spectrum and provide a new test of big bang nucleosynthesis by measuring Y p = 0.326 ± 0.075 (68% CL). We detect, and show on the map for the first time, the tangential and radial polarization patterns around hot and cold spots of temperature fluctuations, an important test of physical processes at z = 1090 and the dominance of adiabatic scalar fluctuations. The seven-year polarization data have significantly improved: we now detect the temperature-E-mode polarization cross power spectrum at 21σ, compared with 13σ from the five-year data. With the seven-year temperature-B-mode cross power spectrum, the limit on a rotation of the polarization plane due to potential parity-violating effects has improved by 38% to Δα = -1. o 1 ± 1. o 4(statistical) ± 1. o 5(systematic) (68% CL). We report significant detections of the Sunyaev-Zel'dovich (SZ) effect at the locations of known clusters of galaxies. The measured SZ signal agrees well with the expected signal from the X-ray data on a cluster-by-cluster basis. However, it is a factor of 0.5-0.7 times the predictions from 'universal profile' of Arnaud et al., analytical models, and hydrodynamical simulations. We find, for the first time in the SZ effect, a significant difference between the cooling-flow and non-cooling-flow clusters (or relaxed and non-relaxed clusters), which can explain some of the discrepancy. This lower amplitude is consistent with the lower-than-theoretically expected SZ power spectrum recently measured by the South Pole Telescope Collaboration.

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

    Science.gov (United States)

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

    1990-01-01

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

  13. Cosmic Extremes: Probing Energetic Transients with Radio Observations

    Science.gov (United States)

    Denham Alexander, Kate

    2018-01-01

    With the advent of sensitive facilities like the Karl G. Jansky Very Large Array (VLA) and planning well underway for vastly more powerful wide-field interferometers like the Square Kilometer Array, the study of radio astrophysical transients is poised for dramatic growth. Radio observations provide a unique window into a wide variety of transient events, from gamma-ray bursts (GRBs) to supernovae to tidal disruption events (TDEs) in which a star is torn apart by a supermassive black hole. In particular, GRBs and TDEs have emerged as valuable probes of some of the most extreme physics in the Universe. In these high-energy laboratories, the longer timescale of radio emission allows for extensive followup and characterization of the event energies and the densities of surrounding material. I will present high-cadence broadband radio studies of GRB afterglows and TDEs undertaken with the goal of learning more about their physical properties, the physics underlying the formation and growth of relativistic jets and outflows, and the environments in which these events occur. Our observations confirm that only a small fraction of TDEs produce relativistic jets but reveal low-luminosity, non-relativistic outflows in two nearby TDEs, allowing us to begin constraining the bulk of the TDE population. Our GRB radio observations reveal both intrinsic variability (reverse shocks) and extrinsic variability (interstellar scintillation). The insights derived from these studies will be invaluable for designing and interpreting the results from future radio transient surveys.

  14. Seismic anisotropy beneath the greater region of the central External Dinarides from observations of SKS-splitting

    Science.gov (United States)

    Subašić, Senad; Prevolnik, Snježan; Herak, Marijan

    2016-04-01

    Measurements of SKS wave splitting beneath greater region of the central External Dinarides (Dalmatia, Croatia) were made in order to investigate seismic anisotropy in the upper mantle and the lithosphere. The area is located in the broad and complex Africa-Eurasia convergent plate boundary zone, where Adriatic microplate interacts with the External Dinarides. We used broadband recordings (more than 3500 analyzed seismograms) from 10 permanent stations situated along the Croatian coastal region. The splitting parameters - fast axis and delay time - were measured using the Silver and Chan method. Seismic anisotropy was observed on all stations. Fast axis directions are fairly uniformly oriented approximately in the NE-SW to NNE-SSW direction, thus perpendicularly to the strike of the Dinarides. Average delay times range between 0.7 and 1.0 seconds. Slight counter-clockwise rotation in average fast axis directions was observed for the stations in the northern part of the studied area, as well as a small increase in average delay times, with respect to the stations in the southern part. We also observed differences in splitting parameters for back-azimuths sampling different tectonic units (Euroasian plate and Adria), however, due to poor back-azimuthal coverage and limited dataset, more measurements have to be made to enable reliable validation of this observation. Fast axis directions coincide with the direction of the maximum tectonic pressure in the crust and with observed fast directions of P-waves in the crust, which might imply a significant crustal component of measured anisotropy, alongside the component resulting from the upper mantle structures.

  15. Direct Observation of Field and Temperature Induced Domain Replication in Dipolar Coupled Perpendicular Anisotropy Films

    Energy Technology Data Exchange (ETDEWEB)

    Hauet, T.; Gunther, C.M.; Pfau, B.; Eisebitt, S.; Fischer, P.; Rick, R. L.; Thiele, J.-U.; Hellwig, O.; Schabes, M.E.

    2007-07-01

    Dipolar interactions in a soft/Pd/hard [CoNi/Pd]{sub 30}/Pd/[Co/Pd]{sub 20} multilayer system, where a thick Pd layer between two ferromagnetic units prevents direct exchange coupling, are directly revealed by combining magnetometry and state-of-the-art layer resolving soft x-ray imaging techniques with sub-100-nm spatial resolution. The domains forming in the soft layer during external magnetic field reversal are found to match the domains previously trapped in the hard layer. The low Curie temperature of the soft layer allows varying its intrinsic parameters via temperature and thus studying the competition with dipolar fields due to the domains in the hard layer. Micromagnetic simulations elucidate the role of [CoNi/Pd] magnetization, exchange, and anisotropy in the duplication process. Finally, thermally driven domain replication in remanence during temperature cycling is demonstrated.

  16. Observation of TeV-Energy Cosmic-Ray Anisotropy with the HAWC Observatory

    Science.gov (United States)

    Fiorino, Daniel W.

    Over the past two decades, ground-based measurements of the arrival directions of TeV cosmic rays have revealed an unexpected anisotropy. Multiple detectors have recorded fluxes above all-sky averages to high statistical significance for features at large (about 180°) and small (about 5°) angular sizes. Likely sources of high-energy cosmic rays are no closer than about 100 pc, about 100,000 Larmor radii for a TeV proton in typical interstellar magnetic fields of order several microGauss. This thesis outlines methods to search for signals in cosmic-ray arrival directions on data from the High-Altitude Water Cherenkov (HAWC) Observatory -- an extended air shower detector array in Puebla, Mexico, sensitive to gamma rays and cosmic rays at TeV energies. The detector is currently under construction, but data acquisition with the partially deployed detector started in 2013. An analysis of the cosmic-ray arrival direction distribution based on 86 billion events recorded between June 2013 and July 2014 shows anisotropy at the 10. (-4) level on angular scales of about 10°. The HAWC cosmic-raysky map exhibits three regions of significantly enhanced cosmic-ray flux; two of these regions were first reported by the Milagro experiment. A third region coincides with an excess recently reported by the ARGO-YBJ experiment. An angular power spectrum analysis of the sky shows that all terms up to l=15 contribute significantly to the excesses. Large angular scales (>60°) are also considered, but the results are still preliminary as they are contaminated with non-sidereal signals which cancel for integer years of continuous data. An analysis of the cosmic-ray Moon shadow is shown to demonstrate the angular resolution and energy scale of the data set and to evaluate part of the analysis technique.

  17. VEGA - international space probe to observe comet Halley

    International Nuclear Information System (INIS)

    Apathy, Istvan; Bereczki, Peterne; Endroeczy, Gabor

    1985-01-01

    The VEGA space probe is to meet comet Halley in 1986 to make in situ measurements. The instruments of the space probe have been manufactured in cooperation of Western and Eastern countries. The orbit, the telemetry system and the operational phases of the probe are described and a brief survey of the instruments is given. The task of the Hungarian made microcomputer tv-system is to recognize the comet and its nucleus, and based on them, to control the platform, to make pictures and to transmit them to the Earth. The spectrometer PLAZMAG is to carry out the measurement of low energy charged particles, the equipment TUENDE-M is to measure high energy ions from the solar wind and the comet itself. The ground support equipment of the central data acquisition system and other equipment have also been developed in Hungary. (author)

  18. The effects of structure anisotropy on lensing observables in an exact general relativistic setting for precision cosmology

    Energy Technology Data Exchange (ETDEWEB)

    Troxel, M. A.; Ishak, Mustapha; Peel, Austin, E-mail: troxel@utdallas.edu, E-mail: mishak@utdallas.edu, E-mail: austin.peel@utdallas.edu [Department of Physics, The University of Texas at Dallas, Richardson, TX 75080 (United States)

    2014-03-01

    The study of relativistic, higher order, and nonlinear effects has become necessary in recent years in the pursuit of precision cosmology. We develop and apply here a framework to study gravitational lensing in exact models in general relativity that are not restricted to homogeneity and isotropy, and where full nonlinearity and relativistic effects are thus naturally included. We apply the framework to a specific, anisotropic galaxy cluster model which is based on a modified NFW halo density profile and described by the Szekeres metric. We examine the effects of increasing levels of anisotropy in the galaxy cluster on lensing observables like the convergence and shear for various lensing geometries, finding a strong nonlinear response in both the convergence and shear for rays passing through anisotropic regions of the cluster. Deviation from the expected values in a spherically symmetric structure are asymmetric with respect to path direction and thus will persist as a statistical effect when averaged over some ensemble of such clusters. The resulting relative difference in various geometries can be as large as approximately 2%, 8%, and 24% in the measure of convergence (1−κ) for levels of anisotropy of 5%, 10%, and 15%, respectively, as a fraction of total cluster mass. For the total magnitude of shear, the relative difference can grow near the center of the structure to be as large as 15%, 32%, and 44% for the same levels of anisotropy, averaged over the two extreme geometries. The convergence is impacted most strongly for rays which pass in directions along the axis of maximum dipole anisotropy in the structure, while the shear is most strongly impacted for rays which pass in directions orthogonal to this axis, as expected. The rich features found in the lensing signal due to anisotropic substructure are nearly entirely lost when one treats the cluster in the traditional FLRW lensing framework. These effects due to anisotropic structures are thus likely to

  19. Probing the Cosmic X-Ray and MeV Gamma-Ray Background Radiation through the Anisotropy

    Energy Technology Data Exchange (ETDEWEB)

    Inoue, Yoshiyuki [Stanford Univ., CA (United States). Kavli Inst. for Particle Astrophysics and Cosmology; SLAC National Accelerator Lab., Menlo Park, CA (United States); Murase, Kohta [Inst. for Advanced Study, Princeton, NJ (United States). School of Natural Sciences; Madejski, Grzegorz M. [Stanford Univ., CA (United States). Kavli Inst. for Particle Astrophysics and Cosmology; SLAC National Accelerator Lab., Menlo Park, CA (United States); Uchiyama, Yasunobu [Stanford Univ., CA (United States). Kavli Inst. for Particle Astrophysics and Cosmology; SLAC National Accelerator Lab., Menlo Park, CA (United States); Rikkyo Univ., Tokyo (Japan). Dept. of Physics

    2013-09-24

    While the cosmic soft X-ray background is very likely to originate from individual Seyfert galaxies, the origin of the cosmic hard X-ray and MeV gamma-ray background is not fully understood. It is expected that Seyferts including Compton thick population may explain the cosmic hard X-ray background. At MeV energy range, Seyferts having non-thermal electrons in coronae above accretion disks or MeV blazars may explain the background radiation. We propose that future measurements of the angular power spectra of anisotropy of the cosmic X-ray and MeV gamma-ray backgrounds will be key to deciphering these backgrounds and the evolution of active galactic nuclei (AGNs). As AGNs trace the cosmic large-scale structure, spatial clustering of AGNs exists. We show that e-ROSITA will clearly detect the correlation signal of unresolved Seyferts at 0.5-2 keV and 2-10 keV bands and will be able to measure the bias parameter of AGNs at both bands. Once the future hard X-ray all sky satellites achieve the sensitivity better than 10-12 erg/cm2/s-1 at 10-30 keV or 30-50 keV - although this is beyond the sensitivities of current hard X-ray all sky monitors - angular power spectra will allow us to independently investigate the fraction of Compton-thick AGNs in all Seyferts. We also find that the expected angular power spectra of Seyferts and blazars in the MeV range are different by about an order of magnitude, where the Poisson term, so-called shot noise, is dominant. Current and future MeV instruments will clearly disentangle the origin of the MeV gamma-ray background through the angular power spectrum.

  20. Probing the cosmic x-ray and MeV gamma ray background radiation through the anisotropy

    Energy Technology Data Exchange (ETDEWEB)

    Inoue, Yoshiyuki [Stanford Univ., CA (United States); Murase, Kohta [Inst. for Advanced Study, Princeton, NJ (United States); Madejski, Grzegorz M. [Stanford Univ., CA (United States); Uchiyama, Yasunobu [Stanford Univ., CA (United States); Rikkyo Univ., Tokyo (Japan)

    2013-09-24

    While the cosmic soft X-ray background is very likely to originate from individual Seyfert galaxies, the origin of the cosmic hard X-ray and MeV gamma-ray background is not fully understood. It is expected that Seyferts including Compton thick population may explain the cosmic hard X-ray background. At MeV energy range, Seyferts having non-thermal electrons in coronae above accretion disks or MeV blazars may explain the background radiation. We propose that future measurements of the angular power spectra of anisotropy of the cosmic X-ray and MeV gamma-ray backgrounds will be key to deciphering these backgrounds and the evolution of active galactic nuclei (AGNs). As AGNs trace the cosmic large-scale structure, spatial clustering of AGNs exists. We show that e-ROSITA will clearly detect the correlation signal of unresolved Seyferts at 0.5-2 keV and 2-10 keV bands and will be able to measure the bias parameter of AGNs at both bands. Once future hard X-ray all sky satellites achieve a sensitivity better than 10–12 erg cm–2 s–1 at 10-30 keV or 30-50 keV—although this is beyond the sensitivities of current hard X-ray all sky monitors—angular power spectra will allow us to independently investigate the fraction of Compton-thick AGNs in all Seyferts. We also find that the expected angular power spectra of Seyferts and blazars in the MeV range are different by about an order of magnitude, where the Poisson term, so-called shot noise, is dominant. Current and future MeV instruments will clearly disentangle the origin of the MeV gamma-ray background through the angular power spectrum.

  1. Observation of correlated azimuthal anisotropy Fourier harmonics in pp and pPb collisions at the LHC

    CERN Document Server

    Sirunyan, Albert M; CMS Collaboration; Adam, Wolfgang; Ambrogi, Federico; Asilar, Ece; Bergauer, Thomas; Brandstetter, Johannes; Brondolin, Erica; Dragicevic, Marko; Erö, Janos; Flechl, Martin; Friedl, Markus; Fruehwirth, Rudolf; Ghete, Vasile Mihai; Grossmann, Johannes; Hrubec, Josef; Jeitler, Manfred; König, Axel; Krammer, Natascha; Krätschmer, Ilse; Liko, Dietrich; Madlener, Thomas; Mikulec, Ivan; Pree, Elias; Rabady, Dinyar; Rad, Navid; Rohringer, Herbert; Schieck, Jochen; Schöfbeck, Robert; Spanring, Markus; Spitzbart, Daniel; Waltenberger, Wolfgang; Wittmann, Johannes; Wulz, Claudia-Elisabeth; Zarucki, Mateusz; Chekhovsky, Vladimir; Mossolov, Vladimir; Suarez Gonzalez, Juan; De Wolf, Eddi A; Di Croce, Davide; Janssen, Xavier; Lauwers, Jasper; Van Haevermaet, Hans; Van Mechelen, Pierre; Van Remortel, Nick; Abu Zeid, Shimaa; Blekman, Freya; D'Hondt, Jorgen; De Bruyn, Isabelle; De Clercq, Jarne; Deroover, Kevin; Flouris, Giannis; Lontkovskyi, Denys; Lowette, Steven; Moortgat, Seth; Moreels, Lieselotte; Python, Quentin; Skovpen, Kirill; Tavernier, Stefaan; Van Doninck, Walter; Van Mulders, Petra; Van Parijs, Isis; Brun, Hugues; Clerbaux, Barbara; De Lentdecker, Gilles; Delannoy, Hugo; Fasanella, Giuseppe; Favart, Laurent; Goldouzian, Reza; Grebenyuk, Anastasia; Karapostoli, Georgia; Lenzi, Thomas; Luetic, Jelena; Maerschalk, Thierry; Marinov, Andrey; Randle-conde, Aidan; Seva, Tomislav; Vander Velde, Catherine; Vanlaer, Pascal; Vannerom, David; Yonamine, Ryo; Zenoni, Florian; Zhang, Fengwangdong; Cimmino, Anna; Cornelis, Tom; Dobur, Didar; Fagot, Alexis; Gul, Muhammad; Khvastunov, Illia; Poyraz, Deniz; Roskas, Christos; Salva Diblen, Sinem; Tytgat, Michael; Verbeke, Willem; Zaganidis, Nicolas; Bakhshiansohi, Hamed; Bondu, Olivier; Brochet, Sébastien; Bruno, Giacomo; Caputo, Claudio; Caudron, Adrien; De Visscher, Simon; Delaere, Christophe; Delcourt, Martin; Francois, Brieuc; Giammanco, Andrea; Jafari, Abideh; Komm, Matthias; Krintiras, Georgios; Lemaitre, Vincent; Magitteri, Alessio; Mertens, Alexandre; Musich, Marco; Piotrzkowski, Krzysztof; Quertenmont, Loic; Vidal Marono, Miguel; Wertz, Sébastien; Beliy, Nikita; Aldá Júnior, Walter Luiz; Alves, Fábio Lúcio; Alves, Gilvan; Brito, Lucas; Correa Martins Junior, Marcos; Hensel, Carsten; Moraes, Arthur; Pol, Maria Elena; Rebello Teles, Patricia; Belchior Batista Das Chagas, Ewerton; Carvalho, Wagner; Chinellato, Jose; Custódio, Analu; Melo Da Costa, Eliza; Da Silveira, Gustavo Gil; De Jesus Damiao, Dilson; Fonseca De Souza, Sandro; Huertas Guativa, Lina Milena; Malbouisson, Helena; Melo De Almeida, Miqueias; Mora Herrera, Clemencia; Mundim, Luiz; Nogima, Helio; Santoro, Alberto; Sznajder, Andre; Tonelli Manganote, Edmilson José; Torres Da Silva De Araujo, Felipe; Vilela Pereira, Antonio; Ahuja, Sudha; Bernardes, Cesar Augusto; Tomei, Thiago; De Moraes Gregores, Eduardo; Mercadante, Pedro G; Novaes, Sergio F; Padula, Sandra; Romero Abad, David; Ruiz Vargas, José Cupertino; Aleksandrov, Aleksandar; Hadjiiska, Roumyana; Iaydjiev, Plamen; Misheva, Milena; Rodozov, Mircho; Shopova, Mariana; Stoykova, Stefka; Sultanov, Georgi; Dimitrov, Anton; Glushkov, Ivan; Litov, Leander; Pavlov, Borislav; Petkov, Peicho; Fang, Wenxing; Gao, Xuyang; Ahmad, Muhammad; Bian, Jian-Guo; Chen, Guo-Ming; Chen, He-Sheng; Chen, Mingshui; Chen, Ye; Jiang, Chun-Hua; Leggat, Duncan; Liao, Hongbo; Liu, Zhenan; Romeo, Francesco; Shaheen, Sarmad Masood; Spiezia, Aniello; Tao, Junquan; Wang, Chunjie; Wang, Zheng; Yazgan, Efe; Zhang, Huaqiao; Zhang, Sijing; Zhao, Jingzhou; Ban, Yong; Chen, Geng; Li, Qiang; Liu, Shuai; Mao, Yajun; Qian, Si-Jin; Wang, Dayong; Xu, Zijun; Avila, Carlos; Cabrera, Andrés; Chaparro Sierra, Luisa Fernanda; Florez, Carlos; González Hernández, Carlos Felipe; Ruiz Alvarez, José David; Courbon, Benoit; Godinovic, Nikola; Lelas, Damir; Puljak, Ivica; Ribeiro Cipriano, Pedro M; Sculac, Toni; Antunovic, Zeljko; Kovac, Marko; Brigljevic, Vuko; Ferencek, Dinko; Kadija, Kreso; Mesic, Benjamin; Starodumov, Andrei; Susa, Tatjana; Ather, Mohsan Waseem; Attikis, Alexandros; Mavromanolakis, Georgios; Mousa, Jehad; Nicolaou, Charalambos; Ptochos, Fotios; Razis, Panos A; Rykaczewski, Hans; Finger, Miroslav; Finger Jr, Michael; Carrera Jarrin, Edgar; Assran, Yasser; Mahmoud, Mohammed; Mahrous, Ayman; Dewanjee, Ram Krishna; Kadastik, Mario; Perrini, Lucia; Raidal, Martti; Tiko, Andres; Veelken, Christian; Eerola, Paula; Pekkanen, Juska; Voutilainen, Mikko; Härkönen, Jaakko; Jarvinen, Terhi; Karimäki, Veikko; Kinnunen, Ritva; Lampén, Tapio; Lassila-Perini, Kati; Lehti, Sami; Lindén, Tomas; Luukka, Panja-Riina; Tuominen, Eija; Tuominiemi, Jorma; Tuovinen, Esa; Talvitie, Joonas; Tuuva, Tuure; Besancon, Marc; Couderc, Fabrice; Dejardin, Marc; Denegri, Daniel; Faure, Jean-Louis; Ferri, Federico; Ganjour, Serguei; Ghosh, Saranya; Givernaud, Alain; Gras, Philippe; Hamel de Monchenault, Gautier; Jarry, Patrick; Kucher, Inna; Locci, Elizabeth; Machet, Martina; Malcles, Julie; Negro, Giulia; Rander, John; Rosowsky, André; Sahin, Mehmet Özgür; Titov, Maksym; Abdulsalam, Abdulla; Amendola, Chiara; Antropov, Iurii; Baffioni, Stephanie; Beaudette, Florian; Busson, Philippe; Cadamuro, Luca; Charlot, Claude; Granier de Cassagnac, Raphael; Jo, Mihee; Lisniak, Stanislav; Lobanov, Artur; Martin Blanco, Javier; Nguyen, Matthew; Ochando, Christophe; Ortona, Giacomo; Paganini, Pascal; Pigard, Philipp; Salerno, Roberto; Sauvan, Jean-Baptiste; Sirois, Yves; Stahl Leiton, Andre Govinda; Strebler, Thomas; Yilmaz, Yetkin; Zabi, Alexandre; Zghiche, Amina; Agram, Jean-Laurent; Andrea, Jeremy; Bloch, Daniel; Brom, Jean-Marie; Buttignol, Michael; Chabert, Eric Christian; Chanon, Nicolas; Collard, Caroline; Conte, Eric; Coubez, Xavier; Fontaine, Jean-Charles; Gelé, Denis; Goerlach, Ulrich; Jansová, Markéta; Le Bihan, Anne-Catherine; Tonon, Nicolas; Van Hove, Pierre; Gadrat, Sébastien; Beauceron, Stephanie; Bernet, Colin; Boudoul, Gaelle; Chierici, Roberto; Contardo, Didier; Depasse, Pierre; El Mamouni, Houmani; Fay, Jean; Finco, Linda; Gascon, Susan; Gouzevitch, Maxime; Grenier, Gérald; Ille, Bernard; Lagarde, Francois; Laktineh, Imad Baptiste; Lethuillier, Morgan; Mirabito, Laurent; Pequegnot, Anne-Laure; Perries, Stephane; Popov, Andrey; Sordini, Viola; Vander Donckt, Muriel; Viret, Sébastien; Toriashvili, Tengizi; Tsamalaidze, Zviad; Autermann, Christian; Feld, Lutz; Kiesel, Maximilian Knut; Klein, Katja; Lipinski, Martin; Preuten, Marius; Schomakers, Christian; Schulz, Johannes; Verlage, Tobias; Zhukov, Valery; Albert, Andreas; Dietz-Laursonn, Erik; Duchardt, Deborah; Endres, Matthias; Erdmann, Martin; Erdweg, Sören; Esch, Thomas; Fischer, Robert; Güth, Andreas; Hamer, Matthias; Hebbeker, Thomas; Heidemann, Carsten; Hoepfner, Kerstin; Knutzen, Simon; Merschmeyer, Markus; Meyer, Arnd; Millet, Philipp; Mukherjee, Swagata; Pook, Tobias; Radziej, Markus; Reithler, Hans; Rieger, Marcel; Scheuch, Florian; Teyssier, Daniel; Thüer, Sebastian; Flügge, Günter; Kargoll, Bastian; Kress, Thomas; Künsken, Andreas; Lingemann, Joschka; Müller, Thomas; Nehrkorn, Alexander; Nowack, Andreas; Pistone, Claudia; Pooth, Oliver; Stahl, Achim; Aldaya Martin, Maria; Arndt, Till; Asawatangtrakuldee, Chayanit; Beernaert, Kelly; Behnke, Olaf; Behrens, Ulf; Bermúdez Martínez, Armando; Bin Anuar, Afiq Aizuddin; Borras, Kerstin; Botta, Valeria; Campbell, Alan; Connor, Patrick; Contreras-Campana, Christian; Costanza, Francesco; Diez Pardos, Carmen; Eckerlin, Guenter; Eckstein, Doris; Eichhorn, Thomas; Eren, Engin; Gallo, Elisabetta; Garay Garcia, Jasone; Geiser, Achim; Gizhko, Andrii; Grados Luyando, Juan Manuel; Grohsjean, Alexander; Gunnellini, Paolo; Guthoff, Moritz; Harb, Ali; Hauk, Johannes; Hempel, Maria; Jung, Hannes; Kalogeropoulos, Alexis; Kasemann, Matthias; Keaveney, James; Kleinwort, Claus; Korol, Ievgen; Krücker, Dirk; Lange, Wolfgang; Lelek, Aleksandra; Lenz, Teresa; Leonard, Jessica; Lipka, Katerina; Lohmann, Wolfgang; Mankel, Rainer; Melzer-Pellmann, Isabell-Alissandra; Meyer, Andreas Bernhard; Mittag, Gregor; Mnich, Joachim; Mussgiller, Andreas; Ntomari, Eleni; Pitzl, Daniel; Raspereza, Alexei; Roland, Benoit; Savitskyi, Mykola; Saxena, Pooja; Shevchenko, Rostyslav; Spannagel, Simon; Stefaniuk, Nazar; Van Onsem, Gerrit Patrick; Walsh, Roberval; Wen, Yiwen; Wichmann, Katarzyna; Wissing, Christoph; Zenaiev, Oleksandr; Bein, Samuel; Blobel, Volker; Centis Vignali, Matteo; Dreyer, Torben; Garutti, Erika; Gonzalez, Daniel; Haller, Johannes; Hinzmann, Andreas; Hoffmann, Malte; Karavdina, Anastasia; Klanner, Robert; Kogler, Roman; Kovalchuk, Nataliia; Kurz, Simon; Lapsien, Tobias; Marchesini, Ivan; Marconi, Daniele; Meyer, Mareike; Niedziela, Marek; Nowatschin, Dominik; Pantaleo, Felice; Peiffer, Thomas; Perieanu, Adrian; Scharf, Christian; Schleper, Peter; Schmidt, Alexander; Schumann, Svenja; Schwandt, Joern; Sonneveld, Jory; Stadie, Hartmut; Steinbrück, Georg; Stober, Fred-Markus Helmut; Stöver, Marc; Tholen, Heiner; Troendle, Daniel; Usai, Emanuele; Vanelderen, Lukas; Vanhoefer, Annika; Vormwald, Benedikt; Akbiyik, Melike; Barth, Christian; Baur, Sebastian; Butz, Erik; Caspart, René; Chwalek, Thorsten; Colombo, Fabio; De Boer, Wim; Dierlamm, Alexander; Freund, Benedikt; Friese, Raphael; Giffels, Manuel; Haitz, Dominik; Hartmann, Frank; Heindl, Stefan Michael; Husemann, Ulrich; Kassel, Florian; Kudella, Simon; Mildner, Hannes; Mozer, Matthias Ulrich; Müller, Thomas; Plagge, Michael; Quast, Gunter; Rabbertz, Klaus; Schröder, Matthias; Shvetsov, Ivan; Sieber, Georg; Simonis, Hans-Jürgen; Ulrich, Ralf; Wayand, Stefan; Weber, Marc; Weiler, Thomas; Williamson, Shawn; Wöhrmann, Clemens; Wolf, Roger; Anagnostou, Georgios; Daskalakis, Georgios; Geralis, Theodoros; Giakoumopoulou, Viktoria Athina; Kyriakis, Aristotelis; Loukas, Demetrios; Topsis-Giotis, Iasonas; Karathanasis, George; Kesisoglou, Stilianos; Panagiotou, Apostolos; Saoulidou, Niki; Kousouris, Konstantinos; Evangelou, Ioannis; Foudas, Costas; Kokkas, Panagiotis; Mallios, Stavros; Manthos, Nikolaos; Papadopoulos, Ioannis; Paradas, Evangelos; Strologas, John; Triantis, Frixos A; Csanad, Mate; Filipovic, Nicolas; Pasztor, Gabriella; Veres, Gabor Istvan; Bencze, Gyorgy; Hajdu, Csaba; Horvath, Dezso; Hunyadi, Ádám; Sikler, Ferenc; Veszpremi, Viktor; Zsigmond, Anna Julia; Beni, Noemi; Czellar, Sandor; Karancsi, János; Makovec, Alajos; Molnar, Jozsef; Szillasi, Zoltan; Bartók, Márton; Raics, Peter; Trocsanyi, Zoltan Laszlo; Ujvari, Balazs; Choudhury, Somnath; Komaragiri, Jyothsna Rani; Bahinipati, Seema; Bhowmik, Sandeep; Mal, Prolay; Mandal, Koushik; Nayak, Aruna; Sahoo, Deepak Kumar; Sahoo, Niladribihari; Swain, Sanjay Kumar; Bansal, Sunil; Beri, Suman Bala; Bhatnagar, Vipin; Chawla, Ridhi; Dhingra, Nitish; Kalsi, Amandeep Kaur; Kaur, Anterpreet; Kaur, Manjit; Kumar, Ramandeep; Kumari, Priyanka; Mehta, Ankita; Singh, Jasbir; Walia, Genius; Kumar, Ashok; Shah, Aashaq; Bhardwaj, Ashutosh; Chauhan, Sushil; Choudhary, Brajesh C; Garg, Rocky Bala; Keshri, Sumit; Kumar, Ajay; Malhotra, Shivali; Naimuddin, Md; Ranjan, Kirti; Sharma, Ramkrishna; Bhardwaj, Rishika; Bhattacharya, Rajarshi; Bhattacharya, Satyaki; Bhawandeep, Bhawandeep; Dey, Sourav; Dutt, Suneel; Dutta, Suchandra; Ghosh, Shamik; Majumdar, Nayana; Modak, Atanu; Mondal, Kuntal; Mukhopadhyay, Supratik; Nandan, Saswati; Purohit, Arnab; Roy, Ashim; Roy, Debarati; Roy Chowdhury, Suvankar; Sarkar, Subir; Sharan, Manoj; Thakur, Shalini; Behera, Prafulla Kumar; Chudasama, Ruchi; Dutta, Dipanwita; Jha, Vishwajeet; Kumar, Vineet; Mohanty, Ajit Kumar; Netrakanti, Pawan Kumar; Pant, Lalit Mohan; Shukla, Prashant; Topkar, Anita; Aziz, Tariq; Dugad, Shashikant; Mahakud, Bibhuprasad; Mitra, Soureek; Mohanty, Gagan Bihari; Sur, Nairit; Sutar, Bajrang; Banerjee, Sudeshna; Bhattacharya, Soham; Chatterjee, Suman; Das, Pallabi; Guchait, Monoranjan; Jain, Sandhya; Kumar, Sanjeev; Maity, Manas; Majumder, Gobinda; Mazumdar, Kajari; Sarkar, Tanmay; Wickramage, Nadeesha; Chauhan, Shubhanshu; Dube, Sourabh; Hegde, Vinay; Kapoor, Anshul; Kothekar, Kunal; Pandey, Shubham; Rane, Aditee; Sharma, Seema; Chenarani, Shirin; Eskandari Tadavani, Esmaeel; Etesami, Seyed Mohsen; Khakzad, Mohsen; Mohammadi Najafabadi, Mojtaba; Naseri, Mohsen; Paktinat Mehdiabadi, Saeid; Rezaei Hosseinabadi, Ferdos; Safarzadeh, Batool; Zeinali, Maryam; Felcini, Marta; Grunewald, Martin; Abbrescia, Marcello; Calabria, Cesare; Colaleo, Anna; Creanza, Donato; Cristella, Leonardo; De Filippis, Nicola; De Palma, Mauro; Errico, Filippo; Fiore, Luigi; Iaselli, Giuseppe; Lezki, Samet; Maggi, Giorgio; Maggi, Marcello; Miniello, Giorgia; My, Salvatore; Nuzzo, Salvatore; Pompili, Alexis; Pugliese, Gabriella; Radogna, Raffaella; Ranieri, Antonio; Selvaggi, Giovanna; Sharma, Archana; Silvestris, Lucia; Venditti, Rosamaria; Verwilligen, Piet; Abbiendi, Giovanni; Battilana, Carlo; Bonacorsi, Daniele; Braibant-Giacomelli, Sylvie; Campanini, Renato; Capiluppi, Paolo; Castro, Andrea; Cavallo, Francesca Romana; Chhibra, Simranjit Singh; Codispoti, Giuseppe; Cuffiani, Marco; Dallavalle, Gaetano-Marco; Fabbri, Fabrizio; Fanfani, Alessandra; Fasanella, Daniele; Giacomelli, Paolo; Grandi, Claudio; Guiducci, Luigi; Marcellini, Stefano; Masetti, Gianni; Montanari, Alessandro; Navarria, Francesco; Perrotta, Andrea; Rossi, Antonio; Rovelli, Tiziano; Siroli, Gian Piero; Tosi, Nicolò; Albergo, Sebastiano; Costa, Salvatore; Di Mattia, Alessandro; Giordano, Ferdinando; Potenza, Renato; Tricomi, Alessia; Tuve, Cristina; Barbagli, Giuseppe; Chatterjee, Kalyanmoy; Ciulli, Vitaliano; Civinini, Carlo; D'Alessandro, Raffaello; Focardi, Ettore; Lenzi, Piergiulio; Meschini, Marco; Paoletti, Simone; Russo, Lorenzo; Sguazzoni, Giacomo; Strom, Derek; Viliani, Lorenzo; Benussi, Luigi; Bianco, Stefano; Fabbri, Franco; Piccolo, Davide; Primavera, Federica; Calvelli, Valerio; Ferro, Fabrizio; Robutti, Enrico; Tosi, Silvano; Benaglia, Andrea; Brianza, Luca; Brivio, Francesco; Ciriolo, Vincenzo; Dinardo, Mauro Emanuele; Fiorendi, Sara; Gennai, Simone; Ghezzi, Alessio; Govoni, Pietro; Malberti, Martina; Malvezzi, Sandra; Manzoni, Riccardo Andrea; Menasce, Dario; Moroni, Luigi; Paganoni, Marco; Pauwels, Kristof; Pedrini, Daniele; Pigazzini, Simone; Ragazzi, Stefano; Redaelli, Nicola; Tabarelli de Fatis, Tommaso; Buontempo, Salvatore; Cavallo, Nicola; Di Guida, Salvatore; Fabozzi, Francesco; Fienga, Francesco; Iorio, Alberto Orso Maria; Khan, Wajid Ali; Lista, Luca; Meola, Sabino; Paolucci, Pierluigi; Sciacca, Crisostomo; Thyssen, Filip; Azzi, Patrizia; Bacchetta, Nicola; Benato, Lisa; Bisello, Dario; Boletti, Alessio; Carlin, Roberto; Carvalho Antunes De Oliveira, Alexandra; Checchia, Paolo; De Castro Manzano, Pablo; Dorigo, Tommaso; Dosselli, Umberto; Gasparini, Fabrizio; Gasparini, Ugo; Gozzelino, Andrea; Lacaprara, Stefano; Margoni, Martino; Meneguzzo, Anna Teresa; Pozzobon, Nicola; Ronchese, Paolo; Rossin, Roberto; Simonetto, Franco; Torassa, Ezio; Zanetti, Marco; Zotto, Pierluigi; Zumerle, Gianni; Braghieri, Alessandro; Magnani, Alice; Montagna, Paolo; Ratti, Sergio P; Re, Valerio; Ressegotti, Martina; Riccardi, Cristina; Salvini, Paola; Vai, Ilaria; Vitulo, Paolo; Alunni Solestizi, Luisa; Biasini, Maurizio; Bilei, Gian Mario; Cecchi, Claudia; Ciangottini, Diego; Fanò, Livio; Lariccia, Paolo; Leonardi, Roberto; Manoni, Elisa; Mantovani, Giancarlo; Mariani, Valentina; Menichelli, Mauro; Rossi, Alessandro; Santocchia, Attilio; Spiga, Daniele; Androsov, Konstantin; Azzurri, Paolo; Bagliesi, Giuseppe; Boccali, Tommaso; Borrello, Laura; Castaldi, Rino; Ciocci, Maria Agnese; Dell'Orso, Roberto; Fedi, Giacomo; Giannini, Leonardo; Giassi, Alessandro; Grippo, Maria Teresa; Ligabue, Franco; Lomtadze, Teimuraz; Manca, Elisabetta; Mandorli, Giulio; Martini, Luca; Messineo, Alberto; Palla, Fabrizio; Rizzi, Andrea; Savoy-Navarro, Aurore; Spagnolo, Paolo; Tenchini, Roberto; Tonelli, Guido; Venturi, Andrea; Verdini, Piero Giorgio; Barone, Luciano; Cavallari, Francesca; Cipriani, Marco; Del Re, Daniele; Di Marco, Emanuele; Diemoz, Marcella; Gelli, Simone; Longo, Egidio; Margaroli, Fabrizio; Marzocchi, Badder; Meridiani, Paolo; Organtini, Giovanni; Paramatti, Riccardo; Preiato, Federico; Rahatlou, Shahram; Rovelli, Chiara; Santanastasio, Francesco; Amapane, Nicola; Arcidiacono, Roberta; Argiro, Stefano; Arneodo, Michele; Bartosik, Nazar; Bellan, Riccardo; Biino, Cristina; Cartiglia, Nicolo; Cenna, Francesca; Costa, Marco; Covarelli, Roberto; Degano, Alessandro; Demaria, Natale; Kiani, Bilal; Mariotti, Chiara; Maselli, Silvia; Migliore, Ernesto; Monaco, Vincenzo; Monteil, Ennio; Monteno, Marco; Obertino, Maria Margherita; Pacher, Luca; Pastrone, Nadia; Pelliccioni, Mario; Pinna Angioni, Gian Luca; Ravera, Fabio; Romero, Alessandra; Ruspa, Marta; Sacchi, Roberto; Shchelina, Ksenia; Sola, Valentina; Solano, Ada; Staiano, Amedeo; Traczyk, Piotr; Belforte, Stefano; Casarsa, Massimo; Cossutti, Fabio; Della Ricca, Giuseppe; Zanetti, Anna; Kim, Dong Hee; Kim, Gui Nyun; Kim, Min Suk; Lee, Jeongeun; Lee, Sangeun; Lee, Seh Wook; Moon, Chang-Seong; Oh, Young Do; Sekmen, Sezen; Son, Dong-Chul; Yang, Yu Chul; Lee, Ari; Kim, Hyunchul; Moon, Dong Ho; Oh, Geonhee; Brochero Cifuentes, Javier Andres; Goh, Junghwan; Kim, Tae Jeong; Cho, Sungwoong; Choi, Suyong; Go, Yeonju; Gyun, Dooyeon; Ha, Seungkyu; Hong, Byung-Sik; Jo, Youngkwon; Kim, Yongsun; Lee, Kisoo; Lee, Kyong Sei; Lee, Songkyo; Lim, Jaehoon; Park, Sung Keun; Roh, Youn; Almond, John; Kim, Junho; Kim, Jae Sung; Lee, Haneol; Lee, Kyeongpil; Nam, Kyungwook; Oh, Sung Bin; Radburn-Smith, Benjamin Charles; Seo, Seon-hee; Yang, Unki; Yoo, Hwi Dong; Yu, Geum Bong; Choi, Minkyoo; Kim, Hyunyong; Kim, Ji Hyun; Lee, Jason Sang Hun; Park, Inkyu; Choi, Young-Il; Hwang, Chanwook; Lee, Jongseok; Yu, Intae; Dudenas, Vytautas; Juodagalvis, Andrius; Vaitkus, Juozas; Ahmed, Ijaz; Ibrahim, Zainol Abidin; Md Ali, Mohd Adli Bin; Mohamad Idris, Faridah; Wan Abdullah, Wan Ahmad Tajuddin; Yusli, Mohd Nizam; Zolkapli, Zukhaimira; Reyes-Almanza, Rogelio; Ramirez-Sanchez, Gabriel; Duran-Osuna, Cecilia; Castilla-Valdez, Heriberto; De La Cruz-Burelo, Eduard; Heredia-De La Cruz, Ivan; Rabadán-Trejo, Raúl Iraq; Lopez-Fernandez, Ricardo; Mejia Guisao, Jhovanny; Sánchez Hernández, Alberto; Carrillo Moreno, Salvador; Oropeza Barrera, Cristina; Vazquez Valencia, Fabiola; Pedraza, Isabel; Salazar Ibarguen, Humberto Antonio; Uribe Estrada, Cecilia; Morelos Pineda, Antonio; Krofcheck, David; Butler, Philip H; Ahmad, Ashfaq; Ahmad, Muhammad; Hassan, Qamar; Hoorani, Hafeez R; Saddique, Asif; Shah, Mehar Ali; Shoaib, Muhammad; Waqas, Muhammad; Bialkowska, Helena; Bluj, Michal; Boimska, Bozena; Frueboes, Tomasz; Górski, Maciej; Kazana, Malgorzata; Nawrocki, Krzysztof; Szleper, Michal; Zalewski, Piotr; Bunkowski, Karol; Byszuk, Adrian; Doroba, Krzysztof; Kalinowski, Artur; Konecki, Marcin; Krolikowski, Jan; Misiura, Maciej; Olszewski, Michal; Pyskir, Andrzej; Walczak, Marek; Bargassa, Pedrame; Beirão Da Cruz E Silva, Cristóvão; Di Francesco, Agostino; Faccioli, Pietro; Galinhas, Bruno; Gallinaro, Michele; Hollar, Jonathan; Leonardo, Nuno; Lloret Iglesias, Lara; Nemallapudi, Mythra Varun; Seixas, Joao; Strong, Giles; Toldaiev, Oleksii; Vadruccio, Daniele; Varela, Joao; Afanasiev, Serguei; Bunin, Pavel; Gavrilenko, Mikhail; Golutvin, Igor; Gorbunov, Ilya; Kamenev, Alexey; Karjavin, Vladimir; Lanev, Alexander; Malakhov, Alexander; Matveev, Viktor; Palichik, Vladimir; Perelygin, Victor; Shmatov, Sergey; Shulha, Siarhei; Skatchkov, Nikolai; Smirnov, Vitaly; Voytishin, Nikolay; Zarubin, Anatoli; Ivanov, Yury; Kim, Victor; Kuznetsova, Ekaterina; Levchenko, Petr; Murzin, Victor; Oreshkin, Vadim; Smirnov, Igor; Sulimov, Valentin; Uvarov, Lev; Vavilov, Sergey; Vorobyev, Alexey; Andreev, Yuri; Dermenev, Alexander; Gninenko, Sergei; Golubev, Nikolai; Karneyeu, Anton; Kirsanov, Mikhail; Krasnikov, Nikolai; Pashenkov, Anatoli; Tlisov, Danila; Toropin, Alexander; Epshteyn, Vladimir; Gavrilov, Vladimir; Lychkovskaya, Natalia; Popov, Vladimir; Pozdnyakov, Ivan; Safronov, Grigory; Spiridonov, Alexander; Stepennov, Anton; Toms, Maria; Vlasov, Evgueni; Zhokin, Alexander; Aushev, Tagir; Bylinkin, Alexander; Chistov, Ruslan; Danilov, Mikhail; Parygin, Pavel; Philippov, Dmitry; Polikarpov, Sergey; Tarkovskii, Evgenii; Zhemchugov, Evgenii; Andreev, Vladimir; Azarkin, Maksim; Dremin, Igor; Kirakosyan, Martin; Terkulov, Adel; Baskakov, Alexey; Belyaev, Andrey; Boos, Edouard; Ershov, Alexander; Gribushin, Andrey; Kaminskiy, Alexandre; Kodolova, Olga; Korotkikh, Vladimir; Lokhtin, Igor; Miagkov, Igor; Obraztsov, Stepan; Petrushanko, Sergey; Savrin, Viktor; Snigirev, Alexander; Vardanyan, Irina; Blinov, Vladimir; Skovpen, Yuri; Shtol, Dmitry; Azhgirey, Igor; Bayshev, Igor; Bitioukov, Sergei; Elumakhov, Dmitry; Kachanov, Vassili; Kalinin, Alexey; Konstantinov, Dmitri; Petrov, Vladimir; Ryutin, Roman; Sobol, Andrei; Troshin, Sergey; Tyurin, Nikolay; Uzunian, Andrey; Volkov, Alexey; Adzic, Petar; Cirkovic, Predrag; Devetak, Damir; Dordevic, Milos; Milosevic, Jovan; Rekovic, Vladimir; Stojanovic, Milan; Alcaraz Maestre, Juan; Barrio Luna, Mar; Cerrada, Marcos; Colino, Nicanor; De La Cruz, Begona; Delgado Peris, Antonio; Escalante Del Valle, Alberto; Fernandez Bedoya, Cristina; Fernández Ramos, Juan Pablo; Flix, Jose; Fouz, Maria Cruz; Garcia-Abia, Pablo; Gonzalez Lopez, Oscar; Goy Lopez, Silvia; Hernandez, Jose M; Josa, Maria Isabel; Moran, Dermot; Pérez-Calero Yzquierdo, Antonio María; Puerta Pelayo, Jesus; Quintario Olmeda, Adrián; Redondo, Ignacio; Romero, Luciano; Senghi Soares, Mara; Álvarez Fernández, Adrian; Albajar, Carmen; de Trocóniz, Jorge F; Missiroli, Marino; Cuevas, Javier; Erice, Carlos; Fernandez Menendez, Javier; Gonzalez Caballero, Isidro; González Fernández, Juan Rodrigo; Palencia Cortezon, Enrique; Sanchez Cruz, Sergio; Vischia, Pietro; Vizan Garcia, Jesus Manuel; Cabrillo, Iban Jose; Calderon, Alicia; Chazin Quero, Barbara; Curras, Esteban; Duarte Campderros, Jordi; Fernandez, Marcos; Garcia-Ferrero, Juan; Gomez, Gervasio; Lopez Virto, Amparo; Marco, Jesus; Martinez Rivero, Celso; Martinez Ruiz del Arbol, Pablo; Matorras, Francisco; Piedra Gomez, Jonatan; Rodrigo, Teresa; Ruiz-Jimeno, Alberto; Scodellaro, Luca; Trevisani, Nicolò; Vila, Ivan; Vilar Cortabitarte, Rocio; Abbaneo, Duccio; Auffray, Etiennette; Baillon, Paul; Ball, Austin; Barney, David; Bianco, Michele; Bloch, Philippe; Bocci, Andrea; Botta, Cristina; Camporesi, Tiziano; Castello, Roberto; Cepeda, Maria; Cerminara, Gianluca; Chapon, Emilien; Chen, Yi; D'Enterria, David; Dabrowski, Anne; Daponte, Vincenzo; David Tinoco Mendes, Andre; De Gruttola, Michele; De Roeck, Albert; Dobson, Marc; Dorney, Brian; Du Pree, Tristan; Dünser, Marc; Dupont, Niels; Elliott-Peisert, Anna; Everaerts, Pieter; Fallavollita, Francesco; Franzoni, Giovanni; Fulcher, Jonathan; Funk, Wolfgang; Gigi, Dominique; Gilbert, Andrew; Gill, Karl; Glege, Frank; Gulhan, Doga; Harris, Philip; Hegeman, Jeroen; Innocente, Vincenzo; Janot, Patrick; Karacheban, Olena; Kieseler, Jan; Kirschenmann, Henning; Knünz, Valentin; Kornmayer, Andreas; Kortelainen, Matti J; Lange, Clemens; Lecoq, Paul; Lourenco, Carlos; Lucchini, Marco Toliman; Malgeri, Luca; Mannelli, Marcello; Martelli, Arabella; Meijers, Frans; Merlin, Jeremie Alexandre; Mersi, Stefano; Meschi, Emilio; Milenovic, Predrag; Moortgat, Filip; Mulders, Martijn; Neugebauer, Hannes; Ngadiuba, Jennifer; Orfanelli, Styliani; Orsini, Luciano; Pape, Luc; Perez, Emmanuel; Peruzzi, Marco; Petrilli, Achille; Petrucciani, Giovanni; Pfeiffer, Andreas; Pierini, Maurizio; Racz, Attila; Reis, Thomas; Rolandi, Gigi; Rovere, Marco; Sakulin, Hannes; Schäfer, Christoph; Schwick, Christoph; Seidel, Markus; Selvaggi, Michele; Sharma, Archana; Silva, Pedro; Sphicas, Paraskevas; Stakia, Anna; Steggemann, Jan; Stoye, Markus; Tosi, Mia; Treille, Daniel; Triossi, Andrea; Tsirou, Andromachi; Veckalns, Viesturs; Verweij, Marta; Zeuner, Wolfram Dietrich; Bertl, Willi; Caminada, Lea; Deiters, Konrad; Erdmann, Wolfram; Horisberger, Roland; Ingram, Quentin; Kaestli, Hans-Christian; Kotlinski, Danek; Langenegger, Urs; Rohe, Tilman; Wiederkehr, Stephan Albert; Bäni, Lukas; Berger, Pirmin; Bianchini, Lorenzo; Casal, Bruno; Dissertori, Günther; Dittmar, Michael; Donegà, Mauro; Grab, Christoph; Heidegger, Constantin; Hits, Dmitry; Hoss, Jan; Kasieczka, Gregor; Klijnsma, Thomas; Lustermann, Werner; Mangano, Boris; Marionneau, Matthieu; Meinhard, Maren Tabea; Meister, Daniel; Micheli, Francesco; Musella, Pasquale; Nessi-Tedaldi, Francesca; Pandolfi, Francesco; Pata, Joosep; Pauss, Felicitas; Perrin, Gaël; Perrozzi, Luca; Quittnat, Milena; Reichmann, Michael; Schönenberger, Myriam; Shchutska, Lesya; Tavolaro, Vittorio Raoul; Theofilatos, Konstantinos; Vesterbacka Olsson, Minna Leonora; Wallny, Rainer; Zhu, De Hua; Aarrestad, Thea Klaeboe; Amsler, Claude; Canelli, Maria Florencia; De Cosa, Annapaola; Del Burgo, Riccardo; Donato, Silvio; Galloni, Camilla; Hreus, Tomas; Kilminster, Benjamin; Pinna, Deborah; Rauco, Giorgia; Robmann, Peter; Salerno, Daniel; Seitz, Claudia; Takahashi, Yuta; Zucchetta, Alberto; Candelise, Vieri; Doan, Thi Hien; Jain, Shilpi; Khurana, Raman; Kuo, Chia-Ming; Lin, Willis; Pozdnyakov, Andrey; Yu, Shin-Shan; Kumar, Arun; Chang, Paoti; Chao, Yuan; Chen, Kai-Feng; Chen, Po-Hsun; Fiori, Francesco; Hou, George Wei-Shu; Hsiung, Yee; Liu, Yueh-Feng; Lu, Rong-Shyang; Paganis, Efstathios; Psallidas, Andreas; Steen, Arnaud; Tsai, Jui-fa; Asavapibhop, Burin; Kovitanggoon, Kittikul; Singh, Gurpreet; Srimanobhas, Norraphat; Boran, Fatma; Cerci, Salim; Damarseckin, Serdal; Demiroglu, Zuhal Seyma; Dozen, Candan; Dumanoglu, Isa; Girgis, Semiray; Gokbulut, Gul; Guler, Yalcin; Hos, Ilknur; Kangal, Evrim Ersin; Kara, Ozgun; Kayis Topaksu, Aysel; Kiminsu, Ugur; Oglakci, Mehmet; Onengut, Gulsen; Ozdemir, Kadri; Sunar Cerci, Deniz; Tali, Bayram; Turkcapar, Semra; Zorbakir, Ibrahim Soner; Zorbilmez, Caglar; Bilin, Bugra; Karapinar, Guler; Ocalan, Kadir; Yalvac, Metin; Zeyrek, Mehmet; Gülmez, Erhan; Kaya, Mithat; Kaya, Ozlem; Tekten, Sevgi; Yetkin, Elif Asli; Nazlim Agaras, Merve; Atay, Serhat; Cakir, Altan; Cankocak, Kerem; Grynyov, Boris; Levchuk, Leonid; Aggleton, Robin; Ball, Fionn; Beck, Lana; Brooke, James John; Burns, Douglas; Clement, Emyr; 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    2018-02-27

    The azimuthal anisotropy Fourier coefficients ($v_n$) in 8.16 TeV pPb data are extracted via long-range two-particle correlations as a function of event multiplicity and compared to corresponding results in pp and PbPb collisions. Using a four-particle cumulant technique, $v_n$ correlations are measured for the first time in pp and pPb collisions. The $v_2$ and $v_4$ coefficients are found to be positively correlated in all collision systems. For high multiplicity pPb collisions an anticorrelation of $v_2$ and $v_3$ is observed, with a similar correlation strength as in PbPb data at the same multiplicity. The new correlation results strengthen the case for a common origin of the collectivity seen in pPb and PbPb collisions in the measured multiplicity range.

  2. Observation of Correlated Azimuthal Anisotropy Fourier Harmonics in pp and p+Pb Collisions at the LHC.

    Science.gov (United States)

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    2018-03-02

    The azimuthal anisotropy Fourier coefficients (v_{n}) in 8.16 TeV p+Pb data are extracted via long-range two-particle correlations as a function of the event multiplicity and compared to corresponding results in pp and PbPb collisions. Using a four-particle cumulant technique, v_{n} correlations are measured for the first time in pp and p+Pb collisions. The v_{2} and v_{4} coefficients are found to be positively correlated in all collision systems. For high-multiplicity p+Pb collisions, an anticorrelation of v_{2} and v_{3} is observed, with a similar correlation strength as in PbPb data at the same multiplicity. The new correlation results strengthen the case for a common origin of the collectivity seen in p+Pb and PbPb collisions in the measured multiplicity range.

  3. Observation of Correlated Azimuthal Anisotropy Fourier Harmonics in p p and p +Pb Collisions at the LHC

    Science.gov (United States)

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S.; Lee, J.; Lee, S.; Lee, S. W.; Moon, C. S.; Oh, Y. D.; Sekmen, S.; Son, D. C.; Yang, Y. C.; Lee, A.; Kim, H.; Moon, D. H.; Oh, G.; Brochero Cifuentes, J. A.; Goh, J.; Kim, T. J.; Cho, S.; Choi, S.; Go, Y.; Gyun, D.; Ha, S.; Hong, B.; Jo, Y.; Kim, Y.; Lee, K.; Lee, K. S.; Lee, S.; Lim, J.; Park, S. K.; Roh, Y.; Almond, J.; Kim, J.; Kim, J. S.; Lee, H.; Lee, K.; Nam, K.; Oh, S. B.; Radburn-Smith, B. C.; Seo, S. h.; Yang, U. K.; Yoo, H. D.; Yu, G. B.; Choi, M.; Kim, H.; Kim, J. H.; Lee, J. S. H.; Park, I. C.; Choi, Y.; Hwang, C.; Lee, J.; Yu, I.; Dudenas, V.; Juodagalvis, A.; Vaitkus, J.; Ahmed, I.; Ibrahim, Z. A.; Md Ali, M. A. B.; Mohamad Idris, F.; Wan Abdullah, W. A. T.; Yusli, M. N.; Zolkapli, Z.; Reyes-Almanza, R.; Ramirez-Sanchez, G.; Duran-Osuna, M. C.; Castilla-Valdez, H.; De La Cruz-Burelo, E.; Heredia-De La Cruz, I.; Rabadan-Trejo, R. 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H.; Barney, D.; Bianco, M.; Bloch, P.; Bocci, A.; Botta, C.; Camporesi, T.; Castello, R.; Cepeda, M.; Cerminara, G.; Chapon, E.; Chen, Y.; d'Enterria, D.; Dabrowski, A.; Daponte, V.; David, A.; De Gruttola, M.; De Roeck, A.; Dobson, M.; Dorney, B.; du Pree, T.; Dünser, M.; Dupont, N.; Elliott-Peisert, A.; Everaerts, P.; Fallavollita, F.; Franzoni, G.; Fulcher, J.; Funk, W.; Gigi, D.; Gilbert, A.; Gill, K.; Glege, F.; Gulhan, D.; Harris, P.; Hegeman, J.; Innocente, V.; Janot, P.; Karacheban, O.; Kieseler, J.; Kirschenmann, H.; Knünz, V.; Kornmayer, A.; Kortelainen, M. J.; Lange, C.; Lecoq, P.; Lourenço, C.; Lucchini, M. T.; Malgeri, L.; Mannelli, M.; Martelli, A.; Meijers, F.; Merlin, J. 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R.; Williams, T.; Auzinger, G.; Bainbridge, R.; Breeze, S.; Buchmuller, O.; Bundock, A.; Casasso, S.; Citron, M.; Colling, D.; Corpe, L.; Dauncey, P.; Davies, G.; De Wit, A.; Della Negra, M.; Di Maria, R.; Elwood, A.; Haddad, Y.; Hall, G.; Iles, G.; James, T.; Lane, R.; Laner, C.; Lyons, L.; Magnan, A.-M.; Malik, S.; Mastrolorenzo, L.; Matsushita, T.; Nash, J.; Nikitenko, A.; Palladino, V.; Pesaresi, M.; Raymond, D. M.; Richards, A.; Rose, A.; Scott, E.; Seez, C.; Shtipliyski, A.; Summers, S.; Tapper, A.; Uchida, K.; Vazquez Acosta, M.; Virdee, T.; Wardle, N.; Winterbottom, D.; Wright, J.; Zenz, S. C.; Cole, J. E.; Hobson, P. R.; Khan, A.; Kyberd, P.; Reid, I. D.; Symonds, P.; Teodorescu, L.; Turner, M.; Borzou, A.; Call, K.; Dittmann, J.; Hatakeyama, K.; Liu, H.; Pastika, N.; Smith, C.; Bartek, R.; Dominguez, A.; Buccilli, A.; Cooper, S. I.; Henderson, C.; Rumerio, P.; West, C.; Arcaro, D.; Avetisyan, A.; Bose, T.; Gastler, D.; Rankin, D.; Richardson, C.; Rohlf, J.; Sulak, L.; Zou, D.; Benelli, G.; Cutts, D.; Garabedian, A.; Hakala, J.; Heintz, U.; Hogan, J. M.; Kwok, K. H. M.; Laird, E.; Landsberg, G.; Mao, Z.; Narain, M.; Piperov, S.; Sagir, S.; Syarif, R.; Yu, D.; Band, R.; Brainerd, C.; Burns, D.; Calderon De La Barca Sanchez, M.; Chertok, M.; Conway, J.; Conway, R.; Cox, P. T.; Erbacher, R.; Flores, C.; Funk, G.; Gardner, M.; Ko, W.; Lander, R.; Mclean, C.; Mulhearn, M.; Pellett, D.; Pilot, J.; Shalhout, S.; Shi, M.; Smith, J.; Stolp, D.; Tos, K.; Tripathi, M.; Wang, Z.; Bachtis, M.; Bravo, C.; Cousins, R.; Dasgupta, A.; Florent, A.; Hauser, J.; Ignatenko, M.; Mccoll, N.; Regnard, S.; Saltzberg, D.; Schnaible, C.; Valuev, V.; Bouvier, E.; Burt, K.; Clare, R.; Ellison, J.; Gary, J. W.; Ghiasi Shirazi, S. M. A.; Hanson, G.; Heilman, J.; Jandir, P.; Kennedy, E.; Lacroix, F.; Long, O. R.; Olmedo Negrete, M.; Paneva, M. I.; Shrinivas, A.; Si, W.; Wang, L.; Wei, H.; Wimpenny, S.; Yates, B. R.; Branson, J. G.; Cittolin, S.; Derdzinski, M.; Hashemi, B.; Holzner, A.; Klein, D.; Kole, G.; Krutelyov, V.; Letts, J.; Macneill, I.; Masciovecchio, M.; Olivito, D.; Padhi, S.; Pieri, M.; Sani, M.; Sharma, V.; Simon, S.; Tadel, M.; Vartak, A.; Wasserbaech, S.; Wood, J.; Würthwein, F.; Yagil, A.; Zevi Della Porta, G.; Amin, N.; Bhandari, R.; Bradmiller-Feld, J.; Campagnari, C.; Dishaw, A.; Dutta, V.; Franco Sevilla, M.; George, C.; Golf, F.; Gouskos, L.; Gran, J.; Heller, R.; Incandela, J.; Mullin, S. D.; Ovcharova, A.; Qu, H.; Richman, J.; Stuart, D.; Suarez, I.; Yoo, J.; Anderson, D.; Bendavid, J.; Bornheim, A.; Lawhorn, J. M.; Newman, H. B.; Nguyen, T.; Pena, C.; Spiropulu, M.; Vlimant, J. R.; Xie, S.; Zhang, Z.; Zhu, R. Y.; Andrews, M. B.; Ferguson, T.; Mudholkar, T.; Paulini, M.; Russ, J.; Sun, M.; Vogel, H.; Vorobiev, I.; Weinberg, M.; Cumalat, J. P.; Ford, W. T.; Jensen, F.; Johnson, A.; Krohn, M.; Leontsinis, S.; Mulholland, T.; Stenson, K.; Wagner, S. R.; Alexander, J.; Chaves, J.; Chu, J.; Dittmer, S.; Mcdermott, K.; Mirman, N.; Patterson, J. R.; Rinkevicius, A.; Ryd, A.; Skinnari, L.; Soffi, L.; Tan, S. M.; Tao, Z.; Thom, J.; Tucker, J.; Wittich, P.; Zientek, M.; Abdullin, S.; Albrow, M.; Apollinari, G.; Apresyan, A.; Apyan, A.; Banerjee, S.; Bauerdick, L. A. T.; Beretvas, A.; Berryhill, J.; Bhat, P. C.; Bolla, G.; Burkett, K.; Butler, J. N.; Canepa, A.; Cerati, G. B.; Cheung, H. W. K.; Chlebana, F.; Cremonesi, M.; Duarte, J.; Elvira, V. D.; Freeman, J.; Gecse, Z.; Gottschalk, E.; Gray, L.; Green, D.; Grünendahl, S.; Gutsche, O.; Harris, R. M.; Hasegawa, S.; Hirschauer, J.; Hu, Z.; Jayatilaka, B.; Jindariani, S.; Johnson, M.; Joshi, U.; Klima, B.; Kreis, B.; Lammel, S.; Lincoln, D.; Lipton, R.; Liu, M.; Liu, T.; Lopes De Sá, R.; Lykken, J.; Maeshima, K.; Magini, N.; Marraffino, J. M.; Maruyama, S.; Mason, D.; McBride, P.; Merkel, P.; Mrenna, S.; Nahn, S.; O'Dell, V.; Pedro, K.; Prokofyev, O.; Rakness, G.; Ristori, L.; Schneider, B.; Sexton-Kennedy, E.; Soha, A.; Spalding, W. J.; Spiegel, L.; Stoynev, S.; Strait, J.; Strobbe, N.; Taylor, L.; Tkaczyk, S.; Tran, N. V.; Uplegger, L.; Vaandering, E. W.; Vernieri, C.; Verzocchi, M.; Vidal, R.; Wang, M.; Weber, H. A.; Whitbeck, A.; Acosta, D.; Avery, P.; Bortignon, P.; Bourilkov, D.; Brinkerhoff, A.; Carnes, A.; Carver, M.; Curry, D.; Field, R. D.; Furic, I. K.; Konigsberg, J.; Korytov, A.; Kotov, K.; Ma, P.; Matchev, K.; Mei, H.; Mitselmakher, G.; Rank, D.; Sperka, D.; Terentyev, N.; Thomas, L.; Wang, J.; Wang, S.; Yelton, J.; Joshi, Y. R.; Linn, S.; Markowitz, P.; Rodriguez, J. L.; Ackert, A.; Adams, T.; Askew, A.; Hagopian, S.; Hagopian, V.; Johnson, K. F.; Kolberg, T.; Martinez, G.; Perry, T.; Prosper, H.; Saha, A.; Santra, A.; Sharma, V.; Yohay, R.; Baarmand, M. M.; Bhopatkar, V.; Colafranceschi, S.; Hohlmann, M.; Noonan, D.; Roy, T.; Yumiceva, F.; Adams, M. R.; Apanasevich, L.; Berry, D.; Betts, R. R.; Cavanaugh, R.; Chen, X.; Evdokimov, O.; Gerber, C. E.; Hangal, D. A.; Hofman, D. J.; Jung, K.; Kamin, J.; Sandoval Gonzalez, I. D.; Tonjes, M. B.; Trauger, H.; Varelas, N.; Wang, H.; Wu, Z.; Zhang, J.; Bilki, B.; Clarida, W.; Dilsiz, K.; Durgut, S.; Gandrajula, R. P.; Haytmyradov, M.; Khristenko, V.; Merlo, J.-P.; Mermerkaya, H.; Mestvirishvili, A.; Moeller, A.; Nachtman, J.; Ogul, H.; Onel, Y.; Ozok, F.; Penzo, A.; Snyder, C.; Tiras, E.; Wetzel, J.; Yi, K.; Blumenfeld, B.; Cocoros, A.; Eminizer, N.; Fehling, D.; Feng, L.; Gritsan, A. V.; Maksimovic, P.; Roskes, J.; Sarica, U.; Swartz, M.; Xiao, M.; You, C.; Al-bataineh, A.; Baringer, P.; Bean, A.; Boren, S.; Bowen, J.; Castle, J.; Khalil, S.; Kropivnitskaya, A.; Majumder, D.; Mcbrayer, W.; Murray, M.; Royon, C.; Sanders, S.; Schmitz, E.; Tapia Takaki, J. D.; Wang, Q.; Ivanov, A.; Kaadze, K.; Maravin, Y.; Mohammadi, A.; Saini, L. K.; Skhirtladze, N.; Toda, S.; Rebassoo, F.; Wright, D.; Anelli, C.; Baden, A.; Baron, O.; Belloni, A.; Calvert, B.; Eno, S. C.; Ferraioli, C.; Hadley, N. J.; Jabeen, S.; Jeng, G. Y.; Kellogg, R. G.; Kunkle, J.; Mignerey, A. C.; Ricci-Tam, F.; Shin, Y. H.; Skuja, A.; Tonwar, S. C.; Abercrombie, D.; Allen, B.; Azzolini, V.; Barbieri, R.; Baty, A.; Bi, R.; Brandt, S.; Busza, W.; Cali, I. A.; D'Alfonso, M.; Demiragli, Z.; Gomez Ceballos, G.; Goncharov, M.; Hsu, D.; Iiyama, Y.; Innocenti, G. M.; Klute, M.; Kovalskyi, D.; Lai, Y. S.; Lee, Y.-J.; Levin, A.; Luckey, P. D.; Maier, B.; Marini, A. C.; Mcginn, C.; Mironov, C.; Narayanan, S.; Niu, X.; Paus, C.; Roland, C.; Roland, G.; Salfeld-Nebgen, J.; Stephans, G. S. F.; Tatar, K.; Velicanu, D.; Wang, J.; Wang, T. W.; Wyslouch, B.; Benvenuti, A. C.; Chatterjee, R. M.; Evans, A.; Hansen, P.; Kalafut, S.; Kubota, Y.; Lesko, Z.; Mans, J.; Nourbakhsh, S.; Ruckstuhl, N.; Rusack, R.; Turkewitz, J.; Acosta, J. G.; Oliveros, S.; Avdeeva, E.; Bloom, K.; Claes, D. R.; Fangmeier, C.; Gonzalez Suarez, R.; Kamalieddin, R.; Kravchenko, I.; Monroy, J.; Siado, J. E.; Snow, G. R.; Stieger, B.; Alyari, M.; Dolen, J.; Godshalk, A.; Harrington, C.; Iashvili, I.; Nguyen, D.; Parker, A.; Rappoccio, S.; Roozbahani, B.; Alverson, G.; Barberis, E.; Hortiangtham, A.; Massironi, A.; Morse, D. M.; Nash, D.; Orimoto, T.; Teixeira De Lima, R.; Trocino, D.; Wood, D.; Bhattacharya, S.; Charaf, O.; Hahn, K. A.; Mucia, N.; Odell, N.; Pollack, B.; Schmitt, M. H.; Sung, K.; Trovato, M.; Velasco, M.; Dev, N.; Hildreth, M.; Hurtado Anampa, K.; Jessop, C.; Karmgard, D. J.; Kellams, N.; Lannon, K.; Loukas, N.; Marinelli, N.; Meng, F.; Mueller, C.; Musienko, Y.; Planer, M.; Reinsvold, A.; Ruchti, R.; Smith, G.; Taroni, S.; Wayne, M.; Wolf, M.; Woodard, A.; Alimena, J.; Antonelli, L.; Bylsma, B.; Durkin, L. S.; Flowers, S.; Francis, B.; Hart, A.; Hill, C.; Ji, W.; Liu, B.; Luo, W.; Puigh, D.; Winer, B. L.; Wulsin, H. W.; Cooperstein, S.; Driga, O.; Elmer, P.; Hardenbrook, J.; Hebda, P.; Higginbotham, S.; Lange, D.; Luo, J.; Marlow, D.; Mei, K.; Ojalvo, I.; Olsen, J.; Palmer, C.; Piroué, P.; Stickland, D.; Tully, C.; Malik, S.; Norberg, S.; Barker, A.; Barnes, V. E.; Das, S.; Folgueras, S.; Gutay, L.; Jha, M. K.; Jones, M.; Jung, A. W.; Khatiwada, A.; Miller, D. H.; Neumeister, N.; Peng, C. C.; Schulte, J. F.; Sun, J.; Wang, F.; Xie, W.; Cheng, T.; Parashar, N.; Stupak, J.; Adair, A.; Akgun, B.; Chen, Z.; Ecklund, K. M.; Geurts, F. J. M.; Guilbaud, M.; Li, W.; Michlin, B.; Northup, M.; Padley, B. P.; Roberts, J.; Rorie, J.; Tu, Z.; Zabel, J.; Bodek, A.; de Barbaro, P.; Demina, R.; Duh, Y. t.; Ferbel, T.; Galanti, M.; Garcia-Bellido, A.; Han, J.; Hindrichs, O.; Khukhunaishvili, A.; Lo, K. H.; Tan, P.; Verzetti, M.; Ciesielski, R.; Goulianos, K.; Mesropian, C.; Agapitos, A.; Chou, J. P.; Gershtein, Y.; Gómez Espinosa, T. A.; Halkiadakis, E.; Heindl, M.; Hughes, E.; Kaplan, S.; Kunnawalkam Elayavalli, R.; Kyriacou, S.; Lath, A.; Montalvo, R.; Nash, K.; Osherson, M.; Saka, H.; Salur, S.; Schnetzer, S.; Sheffield, D.; Somalwar, S.; Stone, R.; Thomas, S.; Thomassen, P.; Walker, M.; Delannoy, A. G.; Foerster, M.; Heideman, J.; Riley, G.; Rose, K.; Spanier, S.; Thapa, K.; Bouhali, O.; Castaneda Hernandez, A.; Celik, A.; Dalchenko, M.; De Mattia, M.; Delgado, A.; Dildick, S.; Eusebi, R.; Gilmore, J.; Huang, T.; Kamon, T.; Mueller, R.; Pakhotin, Y.; Patel, R.; Perloff, A.; Perniè, L.; Rathjens, D.; Safonov, A.; Tatarinov, A.; Ulmer, K. A.; Akchurin, N.; Damgov, J.; De Guio, F.; Dudero, P. R.; Faulkner, J.; Gurpinar, E.; Kunori, S.; Lamichhane, K.; Lee, S. W.; Libeiro, T.; Peltola, T.; Undleeb, S.; Volobouev, I.; Wang, Z.; Greene, S.; Gurrola, A.; Janjam, R.; Johns, W.; Maguire, C.; Melo, A.; Ni, H.; Padeken, K.; Sheldon, P.; Tuo, S.; Velkovska, J.; Xu, Q.; Barria, P.; Cox, B.; Hirosky, R.; Joyce, M.; Ledovskoy, A.; Li, H.; Neu, C.; Sinthuprasith, T.; Wang, Y.; Wolfe, E.; Xia, F.; Harr, R.; Karchin, P. E.; Sturdy, J.; Zaleski, S.; Brodski, M.; Buchanan, J.; Caillol, C.; Dasu, S.; Dodd, L.; Duric, S.; Gomber, B.; Grothe, M.; Herndon, M.; Hervé, A.; Hussain, U.; Klabbers, P.; Lanaro, A.; Levine, A.; Long, K.; Loveless, R.; Pierro, G. A.; Polese, G.; Ruggles, T.; Savin, A.; Smith, N.; Smith, W. H.; Taylor, D.; Woods, N.; CMS Collaboration

    2018-03-01

    The azimuthal anisotropy Fourier coefficients (vn) in 8.16 TeV p +Pb data are extracted via long-range two-particle correlations as a function of the event multiplicity and compared to corresponding results in p p and PbPb collisions. Using a four-particle cumulant technique, vn correlations are measured for the first time in p p and p +Pb collisions. The v2 and v4 coefficients are found to be positively correlated in all collision systems. For high-multiplicity p +Pb collisions, an anticorrelation of v2 and v3 is observed, with a similar correlation strength as in PbPb data at the same multiplicity. The new correlation results strengthen the case for a common origin of the collectivity seen in p +Pb and PbPb collisions in the measured multiplicity range.

  4. Observation of correlated azimuthal anisotropy Fourier harmonics in pp and pPb collisions at the LHC

    Energy Technology Data Exchange (ETDEWEB)

    Sirunyan, Albert M; et al.

    2017-09-26

    The azimuthal anisotropy Fourier coefficients ($v_n$) in 8.16 TeV pPb data are extracted via long-range two-particle correlations as a function of event multiplicity and compared to corresponding results in pp and PbPb collisions. Using a four-particle cumulant technique, $v_n$ correlations are measured for the first time in pp and pPb collisions. The $v_2$ and $v_4$ coefficients are found to be positively correlated in all collision systems. For high multiplicity pPb collisions an anticorrelation of $v_2$ and $v_3$ is observed, with a similar correlation strength as in PbPb data at the same multiplicity. The new correlation results strengthen the case for a common origin of the collectivity seen in pPb and PbPb collisions in the measured multiplicity range.

  5. Dark energy two decades after: observables, probes, consistency tests

    Science.gov (United States)

    Huterer, Dragan; Shafer, Daniel L.

    2018-01-01

    The discovery of the accelerating universe in the late 1990s was a watershed moment in modern cosmology, as it indicated the presence of a fundamentally new, dominant contribution to the energy budget of the universe. Evidence for dark energy, the new component that causes the acceleration, has since become extremely strong, owing to an impressive variety of increasingly precise measurements of the expansion history and the growth of structure in the universe. Still, one of the central challenges of modern cosmology is to shed light on the physical mechanism behind the accelerating universe. In this review, we briefly summarize the developments that led to the discovery of dark energy. Next, we discuss the parametric descriptions of dark energy and the cosmological tests that allow us to better understand its nature. We then review the cosmological probes of dark energy. For each probe, we briefly discuss the physics behind it and its prospects for measuring dark energy properties. We end with a summary of the current status of dark energy research.

  6. Dark energy two decades after: observables, probes, consistency tests.

    Science.gov (United States)

    Huterer, Dragan; Shafer, Daniel L

    2018-01-01

    The discovery of the accelerating universe in the late 1990s was a watershed moment in modern cosmology, as it indicated the presence of a fundamentally new, dominant contribution to the energy budget of the universe. Evidence for dark energy, the new component that causes the acceleration, has since become extremely strong, owing to an impressive variety of increasingly precise measurements of the expansion history and the growth of structure in the universe. Still, one of the central challenges of modern cosmology is to shed light on the physical mechanism behind the accelerating universe. In this review, we briefly summarize the developments that led to the discovery of dark energy. Next, we discuss the parametric descriptions of dark energy and the cosmological tests that allow us to better understand its nature. We then review the cosmological probes of dark energy. For each probe, we briefly discuss the physics behind it and its prospects for measuring dark energy properties. We end with a summary of the current status of dark energy research.

  7. Probing the effect of OSCE checklist length on inter-observer reliability and observer accuracy.

    Science.gov (United States)

    Hurley, Katrina F; Giffin, Nick A; Stewart, Samuel A; Bullock, Graham B

    2015-01-01

    The Objective Structured Clinical Examination (OSCE) is a widely employed tool for measuring clinical competence. In the drive toward comprehensive assessment, OSCE stations and checklists may become increasingly complex. The objective of this study was to probe inter-observer reliability and observer accuracy as a function of OSCE checklist length. Study participants included emergency physicians and senior residents in Emergency Medicine at Dalhousie University. Participants watched an identical series of four, scripted, standardized videos enacting 10-min OSCE stations and completed corresponding assessment checklists. Each participating observer was provided with a random combination of two 40-item and two 20-item checklists. A panel of physicians scored the scenarios through repeated video review to determine the 'gold standard' checklist scores. Fifty-seven observers completed 228 assessment checklists. Mean observer accuracy ranged from 73 to 93% (14.6-18.7/20), with an overall accuracy of 86% (17.2/20), and inter-rater reliability range of 58-78%. After controlling for station and individual variation, no effect was observed regarding the number of checklist items on overall accuracy (p=0.2305). Consistency in ratings was calculated using intraclass correlation coefficient and demonstrated no significant difference in consistency between the 20- and 40-item checklists (ranged from 0.432 to 0.781, p-values from 0.56 to 0.73). The addition of 20 checklist items to a core list of 20 items in an OSCE assessment checklist does not appear to impact observer accuracy or inter-rater reliability.

  8. Wilson loop's phase transition probed by non-local observable

    Directory of Open Access Journals (Sweden)

    Hui-Ling Li

    2018-04-01

    Full Text Available In order to give further insights into the holographic Van der Waals phase transition, it would be of great interest to investigate the behavior of Wilson loop across the holographic phase transition for a higher dimensional hairy black hole. We offer a possibility to proceed with a numerical calculation in order to discussion on the hairy black hole's phase transition, and show that Wilson loop can serve as a probe to detect a phase structure of the black hole. Furthermore, for a first order phase transition, we calculate numerically the Maxwell's equal area construction; and for a second order phase transition, we also study the critical exponent in order to characterize the Wilson loop's phase transition.

  9. High Speed Pump-Probe Apparatus for Observation of Transitional Effects in Ultrafast Laser Micromachining Processes

    Directory of Open Access Journals (Sweden)

    Ilya Alexeev

    2015-12-01

    Full Text Available A pump-probe experimental approach has been shown to be a very efficient tool for the observation and analysis of various laser matter interaction effects. In those setups, synchronized laser pulses are used to create an event (pump and to simultaneously observe it (probe. In general, the physical effects that can be investigated with such an apparatus are restricted by the temporal resolution of the probe pulse and the observation window. The latter can be greatly extended by adjusting the pump-probe time delay under the assumption that the interaction process remains fairly reproducible. Unfortunately, this assumption becomes invalid in the case of high-repetition-rate ultrafast laser material processing, where the irradiation history strongly affects the ongoing interaction process. In this contribution, the authors present an extension of the pump-probe setup that allows to investigate transitional and dynamic effects present during ultrafast laser machining performed at high pulse repetition frequencies.

  10. Relationship between electron field-aligned anisotropy and dawn-dusk magnetic field: Nine years of Cluster observations in the Earth magnetotail

    Science.gov (United States)

    Yushkov, E.; Petrukovich, A.; Artemyev, A.; Nakamura, R.

    2017-09-01

    We investigate the distribution and possible origins of thermal anisotropic electrons in the Earth's magnetotail, using 9 years of Cluster observations. We mainly focus on relation between electron anisotropy and Bz and By magnetic field components (in GSM coordinates). The anisotropy of electron population is characterized by temperature ratio T∥/T⊥ and by the maximum of phase space density ratio F∥/F⊥ (∥ and ⊥ are relative to the background magnetic field). The population identified by large F∥/F⊥ is organized as short-time (dozens of seconds) bursts with enhanced F∥ and can be observed even in the plasma sheet with small T∥/T⊥. The thermal anisotropy T∥/T⊥ is larger for time intervals characterized by stronger Bz and By: the strong By corresponds to the T∥/T⊥ peak around the magnetotail neutral plane Bx=0, whereas the strong Bz corresponds to larger T∥/T⊥ with a flat profile across the magnetotail. There is a dawn-dusk asymmetry: large T∥/T⊥ corresponds mostly to strong Bz at the dusk flank and to strong By at the dawn flank. Using these differences of the electron anisotropy dependence on By and Bz, we discuss two possible mechanisms responsible for the anisotropy formation.

  11. Probing Dark Matter using X-ray Observations

    Science.gov (United States)

    Bulbul, E.

    2017-10-01

    A well-motivated warm dark matter candidate, sterile neutrinos, can radiatively decay and emit X-rays detectable in observations of large dark matter aggregations such as galaxies and clusters of galaxies. I will review the current and past efforts on searching for decaying dark matter in galaxy clusters and galaxies with a special focus on the 3.5 keV line. Additionally, I will summarize how the recent constraints can be improved using the future Athena XIFU observations.

  12. Distinctive orbital anisotropy observed in the nematic state of a FeSe thin film

    International Nuclear Information System (INIS)

    Zhang, Y.; Lawrence Berkeley National Laboratory; Yi, M.; Stanford University, CA; Liu, Z.-K.

    2016-01-01

    Nematic state, where the system is translationally invariant but breaks the rotational symmetry, has drawn great attentions recently due to experimental observations of such a state in both cuprates and iron-based superconductors. The mechanism of nematicity that is likely tied to the pairing mechanism of high-T c , however, still remains controversial. Here, we studied the electronic structure of multilayer FeSe film by angle-resolved photoemission spectroscopy (ARPES). We found that the FeSe film enters the nematic state around 125 K, while the electronic signature of long range magnetic order has not been observed down to 20K indicating the non-magnetic origin of the nematicity. The band reconstruction in the nematic state is characterized by the splitting of the d xz and d yz bands. More intriguingly, such energy splitting is strong momentum dependent with the largest band splitting of ~80 meV at the zone corner. The simple on-site ferro-orbital ordering is insufficient to reproduce the nontrivial momentum dependence of the band reconstruction. Instead, our results suggest that the nearest-neighbor hopping of d xz and d yz is highly anisotropic in the nematic state, the origin of which holds the key in understanding the nematicity in iron-based superconductors.

  13. Observation of Various and Spontaneous Magnetic Skyrmionic Bubbles at Room Temperature in a Frustrated Kagome Magnet with Uniaxial Magnetic Anisotropy

    KAUST Repository

    Hou, Zhipeng

    2017-06-07

    The quest for materials hosting topologically protected skyrmionic spin textures continues to be fueled by the promise of novel devices. Although many materials have demonstrated the existence of such spin textures, major challenges remain to be addressed before devices based on magnetic skyrmions can be realized. For example, being able to create and manipulate skyrmionic spin textures at room temperature is of great importance for further technological applications because they can adapt to various external stimuli acting as information carriers in spintronic devices. Here, the first observation of skyrmionic magnetic bubbles with variable topological spin textures formed at room temperature in a frustrated kagome Fe3 Sn2 magnet with uniaxial magnetic anisotropy is reported. The magnetization dynamics are investigated using in situ Lorentz transmission electron microscopy, revealing that the transformation between different magnetic bubbles and domains is via the motion of Bloch lines driven by an applied external magnetic field. These results demonstrate that Fe3 Sn2 facilitates a unique magnetic control of topological spin textures at room temperature, making it a promising candidate for further skyrmion-based spintronic devices.

  14. Combining microscopic and macroscopic probes to untangle the single-ion anisotropy and exchange energies in an S =1 quantum antiferromagnet

    Science.gov (United States)

    Brambleby, Jamie; Manson, Jamie L.; Goddard, Paul A.; Stone, Matthew B.; Johnson, Roger D.; Manuel, Pascal; Villa, Jacqueline A.; Brown, Craig M.; Lu, Helen; Chikara, Shalinee; Zapf, Vivien; Lapidus, Saul H.; Scatena, Rebecca; Macchi, Piero; Chen, Yu-sheng; Wu, Lai-Chin; Singleton, John

    2017-04-01

    The magnetic ground state of the quasi-one-dimensional spin-1 antiferromagnetic chain is sensitive to the relative sizes of the single-ion anisotropy (D ) and the intrachain (J ) and interchain (J') exchange interactions. The ratios D /J and J'/J dictate the material's placement in one of three competing phases: a Haldane gapped phase, a quantum paramagnet, and an X Y -ordered state, with a quantum critical point at their junction. We have identified [Ni (HF2) (pyz) 2] SbF6 , where pyz = pyrazine, as a rare candidate in which this behavior can be explored in detail. Combining neutron scattering (elastic and inelastic) in applied magnetic fields of up to 10 tesla and magnetization measurements in fields of up to 60 tesla with numerical modeling of experimental observables, we are able to obtain accurate values of all of the parameters of the Hamiltonian [D =13.3 (1 ) K, J =10.4 (3 ) K, and J'=1.4 (2 ) K], despite the polycrystalline nature of the sample. Density-functional theory calculations result in similar couplings (J =9.2 K, J'=1.8 K) and predict that the majority of the total spin population resides on the Ni(II) ion, while the remaining spin density is delocalized over both ligand types. The general procedures outlined in this paper permit phase boundaries and quantum-critical points to be explored in anisotropic systems for which single crystals are as yet unavailable.

  15. Spintronic magnetic anisotropy

    OpenAIRE

    Misiorny, Maciej; Hell, Michael; Wegewijs, Maarten R.

    2014-01-01

    An attractive feature of magnetic adatoms and molecules for nanoscale applications is their superparamagnetism, the preferred alignment of their spin along an easy axis preventing undesired spin reversal. The underlying magnetic anisotropy barrier --a quadrupolar energy splitting-- is internally generated by spin-orbit interaction and can nowadays be probed by electronic transport. Here we predict that in a much broader class of quantum-dot systems with spin larger than one-half, superparamag...

  16. Observation of nanostructure by scanning near-field optical microscope with small sphere probe

    Directory of Open Access Journals (Sweden)

    Yasushi Oshikane, Toshihiko Kataoka, Mitsuru Okuda, Seiji Hara, Haruyuki Inoue and Motohiro Nakano

    2007-01-01

    Full Text Available Step and terrace structure has been observed in an area of 1 μm×1 μm on the cleaved surface of KCl–KBr solid-solution single crystal by scanning near-field optical microscope (SNOM with a small sphere probe of 500 nm diameter. Lateral spatial resolution of the SNOM system was estimated to be 20 nm from the observation of step width and the scanning-step interval. Vertical spatial resolution was estimated to be 5–2 nm from the observation of step height and noise level of photomultiplier tube (PMT. With applying a dielectric dipole radiation model to the probe surface, the reason why such a high spatial resolution was obtained in spite of the 500 nm sphere probe, was understood as the effect of the near-field term appeared in the radiation field equations.

  17. The Inner Magnetosphere Plasma Response to Interplanetary Shocks: Van Allen Probes HOPE Observations

    Science.gov (United States)

    Winter, L. M.; Denton, M.; Ferradas, C.; Henderson, M. G.; Larsen, B.; Reeves, G.; Skoug, R. M.; Thomsen, M. F.

    2017-12-01

    The Van Allen Probes' Helium, Oxygen, Proton, and Electron (HOPE) sensors measure ion and electron populations in the plasmasphere, plasma sheet, and lower-energy ring current, providing unique observations at low energies (0.001-50 keV) and low L-shell (down to 1.5 RE). We use the capabilities of these two spacecraft to probe changes in the low energy particles in response to interplanetary (IP) shocks. We focus on changes in the plasma energies, composition, and pitch angle distributions following IP shocks and storm sudden commencements from 2012-2017 through a comparison of HOPE observations preceding and post shock.

  18. Observation of the in-plane spin-dephasing anisotropy in [111]-grown GaAs/AlGaAs quantum well

    International Nuclear Information System (INIS)

    Zhao, Chunbo; Li, Junbin; Yu, Ying; Ni, Haiqiao; Niu, Zhichuan; Zhang, Xinhui

    2014-01-01

    The electron density and temperature dependent in-plane spin-dephasing anisotropy in [111]-grown GaAs quantum well (QW) has been investigated by time-resolved magneto-Kerr rotation technique. Due to the specific symmetry of [111]-grown quantum well, the in-plane Rashba and linear Dresselhaus effective spin-orbit magnetic field is parallel to each other for electron wave vectors in all directions. However, an obvious in-plane spin-dephasing anisotropy comparing [2 ¯ 11] with [01 ¯ 1] crystalline orientations has been observed and discussed in this work. Our results demonstrate the innegligible spin dephasing channel through inhomogeneous broadening induced by the out-of-plane non-linear Dresselhaus field, which arises naturally from the C 3 symmetry of [111]-grown GaAs QW

  19. Probing the possibility of a 12C13C abundance gradient from observations of interstellar CH+

    International Nuclear Information System (INIS)

    Hawkins, I.

    1987-01-01

    I have performed high signal-to-noise (SN /equals/ 300 to 500) observations of interstellar CH/sup /plus// at Lick Observatory and at CTIO of the reddened, early-type stars HD 183143, HD 24432, and HD 157038 in an effort to probe the existence of a 12 C 13 C abundance gradient in our Galaxy

  20. Crustal anisotropy in the Bohemian Massif, Czech Republic: observations based on Central European Lithospheric Experiment Based on Refraction (CELEBRATION) 2000

    Czech Academy of Sciences Publication Activity Database

    Růžek, Bohuslav; Vavryčuk, Václav; Hrubcová, Pavla; Zedník, Jan; Guterch, A.; Grad, M.; Keller, G. R.; Posgay, K.; Vozár, J.; Špičák, Aleš; Brückl, E.; Hajnal, Z.; Thybo, H.; Selvi, O.

    2003-01-01

    Roč. 108, B8 (2003), s. 2392, ESE 9-1-9-15, doi:10.1029/2002JB002242 ISSN 0148-0227 R&D Projects: GA ČR GA205/00/1350 Institutional research plan: CEZ:AV0Z3012916 Keywords : anisotropy * Bohemian Massif * Earth's crust * seismic waves Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 2.992, year: 2003

  1. Magnetic anisotropy of (Ge,Mn) nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Jain, A; Jamet, M; Barski, A; Devillers, T; Yu, I-S; Porret, C; Gambarelli, S; Maurel, V; Desfonds, G; Jacquot, J F, E-mail: abhinav.jain@cea.fr [Institut Nanosciences et Cryogenie, CEA-UJF, F-38054, Grenoble (France)

    2011-04-01

    We present a correlation between structural and magnetic properties of different (Ge,Mn) nanostructures grown on Ge(001) and Ge(111) substrates. Thin films of Ge{sub 1-x}Mn{sub x} were grown by low temperature molecular beam epitaxy to favor the out-of-equilibrium growth. Depending on the growth conditions crystalline or amorphous (Ge,Mn) nanocolumns have been observed on Ge(001) substrates. The magnetic properties were probed by superconducting quantum interference device (SQUID), vibrating sample magnetometer (VSM) and electron paramagnetic resonance (EPR). With the help of these complementary techniques (SQUID and EPR), magnetic anisotropy in these nanostructures has been investigated and different anisotropy constants were calculated.

  2. Observations of Mesospheric Turbulence by Rocket Probe and VHF Radar, Part 2.4A

    Science.gov (United States)

    Royrvik, O.; Smith, L. G.

    1984-01-01

    Data from the Jicamarca VHF radar and from a Languir probe fine-structure on a Nike Orion rocket launched from Punto Lobos, Peru, have been compared. A single mesospheric scattering layer was observed by the radar. The Langmuir probe detected irregularities in the electron-density profile in a narrow region between 85.2 and 86.6 km. It appears from a comparison between these two data sets that turbulence in the neutral atmosphere is the mechanism generating the refractive index irregularities.

  3. Flexibility of Enzymes Suspended in Organic Solvents Probed by Time-Resolved Fluorescence Anisotropy. Evidence That Enzyme Activity and Enantioselectivity Are Directly Related to Enzyme Flexibility

    NARCIS (Netherlands)

    Broos, Jaap; Visser, Antonie J.W.G.; Engbersen, Johan F.J.; Verboom, Willem; Hoek, Arie van; Reinhoudt, David N.

    1995-01-01

    A time-resolved fluorescence anisotropy study on the molecular flexibility of active-site labeled anthraniloyl-α-chymotrypsin, dansylsubtilisin Carlsberg, and native subtilisin Carlsberg, suspended in organic solvents, is described. The internal rotational mobility of the fluorophore in the

  4. The jumps of physical quantities at fast shocks under pressure anisotropy: theory versus observations at the bow shock

    International Nuclear Information System (INIS)

    Vogl, D.F.

    2000-10-01

    The interaction of the solar wind with magnetized planets leads to the formation of the so-called magnetosphere, a cavity generated by the geomagnetic field. The supersonic, superalfvenic, and magnetized solar wind flow interacting with blunt bodies produces a detached bow shock, separating the solar wind from the magnetosheath, the region between the shock wave and the magnetopause. On approach to a planetary obstacle, the solar wind becomes subsonic at the bow shock and then flows past the planet in the magnetosheath. At the bow shock, the plasma parameters and the magnetic field strength change from upstream to downstream, i.e., an increase of plasma density, temperature, pressure, and magnetic field strength, and a decrease of the velocity across the shock. In this PhD thesis we mainly concentrate on the variations of all physical quantities across the bow shock taking into account pressure anisotropy, which is an important feature in space plasma physics and observed by various spacecraft missions in the solar wind as well as in the magnetosheath. Dealing with anisotropic plasma conditions, one has to introduce the so-called pressure tensor, characterized by two scalar pressures, the pressure perpendicular (P p erp) and the pressure parallel (P p arallel) with respect to the magnetic field and in general one speaks of anisotropic conditions for P p erp is not P p arallel. Many spacecraft observations of the solar wind show P p arallel > P p erp, whereas observations of the magnetosheath show the opposite case, P p arallel p erp. Therefore, dissipation of kinetic energy into thermal energy plays an important role in studying the variations of the relevant physical quantities across the shock. It has to be mentioned that planetary bow shocks are good examples for fast MHD shock waves. Therefore, the basic equations for describing the changes across the shock can be obtained by integrating the MHD equations in conservative form. We note that these equations, the

  5. Observation and manipulation of glial cell function by virtue of sufficient probe expression.

    Directory of Open Access Journals (Sweden)

    Akiyo eNatsubori

    2015-05-01

    Full Text Available The development of gene-encoded indicators and actuators to observe and manipulate cellular functions is being advanced and investigated. Expressing these probe molecules in glial cells is expected to enable observation and manipulation of glial cell activity, leading to elucidate the behaviors and causal roles of glial cells. The first step toward understanding glial cell functions is to express the probes in sufficient amounts, and the Knockin-mediated ENhanced Gene Expression (KENGE-tet system provides a strategy for achieving this. In the present article, three examples of KENGE-tet system application are reviewed: depolarization of oligodendrocytes, intracellular acidification of astrocytes, and observation of intracellular calcium levels in the fine processes of astrocytes.

  6. Propagation of Dipolarization Signatures Observed by the Van Allen Probes in the Inner Magnetosphere

    Science.gov (United States)

    Ohtani, S.; Motoba, T.; Gkioulidou, M.; Takahashi, K.; Kletzing, C.

    2017-12-01

    Dipolarization, the change of the local magnetic field from a stretched to a more dipolar configuration, is one of the most fundamental processes of magnetospheric physics. It is especially critical for the dynamics of the inner magnetosphere. The associated electric field accelerates ions and electrons and transports them closer to Earth. Such injected ions intensify the ring current, and electrons constitute the seed population of the radiation belt. Those ions and electrons may also excite various waves that play important roles in the enhancement and loss of the radiation belt electrons. Despite such critical consequences, the general characteristics of dipolarization in the inner magnetosphere still remain to be understood. The Van Allen Probes mission, which consists of two probes that orbit through the equatorial region of the inner magnetosphere, provides an ideal opportunity to examine dipolarization signatures in the core of the ring current. In the present study we investigate the spatial expansion of the dipolarization region by examining the correlation and time delay of dipolarization signatures observed by the two probes. Whereas in general it requires three-point measurements to deduce the propagation of a signal on a certain plane, we statically examined the observed time delays and found that dipolarization signatures tend to propagate radially inward as well as away from midnight. In this paper we address the propagation of dipolarization signatures quantitatively and compare with the propagation velocities reported previously based on observations made farther away from Earth. We also discuss how often and under what conditions the dipolarization region expands.

  7. Multipoint observations of energetic electron injections with MMS and Van Allen Probes

    Science.gov (United States)

    Turner, D. L.; Fennell, J. F.; Blake, J. B.; Claudepierre, S. G.; Jaynes, A. N.; Baker, D. N.; Reeves, G. D.; Cohen, I. J.; Mauk, B.; Li, W.; Kletzing, C.; Torbert, R. B.; Burch, J. L.

    2016-12-01

    Between March and September of 2016, the orbits of NASA's Magnetospheric Multiscale (MMS) and Van Allen Probes missions overlapped on the dawn side of the near-equatorial magnetosphere, a region ideal for studying injections of 10s to 100s of keV electrons from the plasma sheet into the inner magnetosphere. During this period, the four MMS spacecraft also underwent a series of conjunctions with both Van Allen Probes, including several in which all six spacecraft were within 1 Earth radii of each other. From such multipoint observations, we investigate the connection between Earth's magnetotail and inner magnetosphere via dipolarization events and the energetic particle injections associated with them. Using the multipoint MMS data, we show how dipolarization fronts surge earthwards through the tail at 100s of kilometers per second, corresponding to strong electric fields that accelerate energetic particles and transport them earthward. Combining MMS with Van Allen Probes, we are able to estimate the transport of particles over larger spatial scales (macroscopic view) and multipoint observations of wave activity during close conjunctions (microscopic view). With such observations, we examine and report on new perspectives concerning the role of energetic electron injections as the seed populations of Earth's outer radiation belt electrons as well as the relationship between freshly injected electrons and chorus and ultra-low frequency (ULF) wave activity.

  8. Van Allen Probes observations of unusually low frequency whistler mode waves observed in association with moderate magnetic storms: Statistical study

    OpenAIRE

    Cattell, C. A.; Breneman, A. W.; Thaller, S. A.; Wygant, J. R.; Kletzing, C. A.; Kurth, W. S.

    2015-01-01

    Abstract We show the first evidence for locally excited chorus at frequencies below 0.1?f ce (electron cyclotron frequency) in the outer radiation belt. A statistical study of chorus during geomagnetic storms observed by the Van Allen Probes found that frequencies are often dramatically lower than expected. The frequency at peak power suddenly stops tracking the equatorial 0.5?f ce and f/f ce decreases rapidly, often to frequencies well below 0.1?f ce (in situ and mapped to equator). These ve...

  9. Observation of small-scale anisotropy in the arrival direction distribution of TeV cosmic rays with HAWC

    Energy Technology Data Exchange (ETDEWEB)

    Abeysekara, A. U. [Department of Physics and Astronomy, Michigan State University, East Lansing, MI (United States); Alfaro, R.; Belmont, E. [Instituto de Física, Universidad Nacional Autónoma de México, Mexico D.F. (Mexico); Alvarez, C.; Arceo, R. [CEFyMAP, Universidad Autónoma de Chiapas, Tuxtla Gutiérrez, Chiapas (Mexico); Álvarez, J. D.; Arteaga-Velázquez, J. C.; Cotti, U. [Universidad Michoacana de San Nicolás de Hidalgo, Morelia (Mexico); Ayala Solares, H. A. [Department of Physics, Michigan Technological University, Houghton, MI (United States); Barber, A. S. [Department of Physics and Astronomy, University of Utah, Salt Lake City, UT (United States); Baughman, B. M.; Berley, D.; Braun, J. [Department of Physics, University of Maryland, College Park, MD (United States); Bautista-Elivar, N. [Universidad Politécnica de Pachuca, Pachuca, Hidalgo (Mexico); BenZvi, S. Y. [Department of Physics and Astronomy, University of Rochester, Rochester, NY (United States); Bonilla Rosales, M.; Carramiñana, A. [Instituto Nacional de Astrofísica, Óptica y Electrónica, Tonantzintla, Puebla (Mexico); Caballero-Mora, K. S. [Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Mexico D.F. (Mexico); Castillo, M.; Cotzomi, J., E-mail: dan.fiorino@wipac.wisc.edu [Facultad de Ciencias Físico Matemáticas, Benemérita Universidad Autónoma de Puebla, Puebla (Mexico); Collaboration: HAWC Collaboration; and others

    2014-12-01

    The High-Altitude Water Cherenkov (HAWC) Observatory is sensitive to gamma rays and charged cosmic rays at TeV energies. The detector is still under construction, but data acquisition with the partially deployed detector started in 2013. An analysis of the cosmic-ray arrival direction distribution based on 4.9 × 10{sup 10} events recorded between 2013 June and 2014 February shows anisotropy at the 10{sup –4} level on angular scales of about 10°. The HAWC cosmic-ray sky map exhibits three regions of significantly enhanced cosmic-ray flux; two of these regions were first reported by the Milagro experiment. A third region coincides with an excess recently reported by the ARGO-YBJ experiment. An angular power spectrum analysis of the sky shows that all terms up to ℓ = 15 contribute significantly to the excesses.

  10. Probes and Tests of Strong-Field Gravity with Observations in the Electromagnetic Spectrum

    Directory of Open Access Journals (Sweden)

    Psaltis Dimitrios

    2008-11-01

    Full Text Available Neutron stars and black holes are the astrophysical systems with the strongest gravitational fields in the universe. In this article, I review the prospect of using observations of such compact objects to probe some of the most intriguing general relativistic predictions in the strong-field regime: the absence of stable circular orbits near a compact object and the presence of event horizons around black-hole singularities. I discuss the need for a theoretical framework, within which future experiments will provide detailed, quantitative tests of gravity theories. Finally, I summarize the constraints imposed by current observations of neutron stars on potential deviations from general relativity.

  11. ARGO-YBJ OBSERVATION OF THE LARGE-SCALE COSMIC RAY ANISOTROPY DURING THE SOLAR MINIMUM BETWEEN CYCLES 23 AND 24

    Energy Technology Data Exchange (ETDEWEB)

    Bartoli, B.; Catalanotti, S.; Piazzoli, B. D’Ettorre; Girolamo, T. Di [Dipartimento di Fisica dell’Università di Napoli “Federico II”, Complesso Universitario di Monte Sant’Angelo, via Cinthia, I-80126 Napoli (Italy); Bernardini, P.; D’Amone, A.; Mitri, I. De [Dipartimento Matematica e Fisica ”Ennio De Giorgi”, Università del Salento, via per Arnesano, I-73100 Lecce (Italy); Bi, X. J.; Cao, Z.; Chen, S. Z.; Feng, Zhaoyang; Gou, Q. B. [Key Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences, P.O. Box 918, 100049 Beijing (China); Chen, T. L.; Danzengluobu [Tibet University, 850000 Lhasa, Xizang (China); Cui, S. W.; Gao, W. [Hebei Normal University, 050024, Shijiazhuang Hebei (China); Dai, B. Z. [Yunnan University, 2 North Cuihu Road, 650091 Kunming, Yunnan (China); Sciascio, G. Di [Istituto Nazionale di Fisica Nucleare, Sezione di Roma Tor Vergata, via della Ricerca Scientifica 1, I-00133 Roma (Italy); Feng, C. F. [Shandong University, 250100 Jinan, Shandong (China); Feng, Zhenyong, E-mail: cuisw@ihep.ac.cn [Southwest Jiaotong University, 610031 Chengdu, Sichuan (China); Collaboration: ARGO-YBJ Collaboration; and others

    2015-08-10

    This paper reports on the measurement of the large-scale anisotropy in the distribution of cosmic-ray arrival directions using the data collected by the air shower detector ARGO-YBJ from 2008 January to 2009 December, during the minimum of solar activity between cycles 23 and 24. In this period, more than 2 × 10{sup 11} showers were recorded with energies between ∼1 and 30 TeV. The observed two-dimensional distribution of cosmic rays is characterized by two wide regions of excess and deficit, respectively, both of relative intensity ∼10{sup −3} with respect to a uniform flux, superimposed on smaller size structures. The harmonic analysis shows that the large-scale cosmic-ray relative intensity as a function of R.A. can be described by the first and second terms of a Fouries series. The high event statistics allow the study of the energy dependence of the anistropy, showing that the amplitude increases with energy, with a maximum intensity at ∼10 TeV, and then decreases while the phase slowly shifts toward lower values of R.A. with increasing energy. The ARGO-YBJ data provide accurate observations over more than a decade of energy around this feature of the anisotropy spectrum.

  12. Swelling-induced optical anisotropy of thermoresponsive hydrogels based on poly(2-(2-methoxyethoxy)ethyl methacrylate): deswelling kinetics probed by quantitative Mueller matrix polarimetry.

    Science.gov (United States)

    Patil, Nagaraj; Soni, Jalpa; Ghosh, Nirmalya; De, Priyadarsi

    2012-11-29

    Thermodynamically favored polymer-water interactions below the lower critical solution temperature (LCST) caused swelling-induced optical anisotropy (linear retardance) of thermoresponsive hydrogels based on poly(2-(2-methoxyethoxy)ethyl methacrylate). This was exploited to study the macroscopic deswelling kinetics quantitatively by a generalized polarimetry analysis method, based on measurement of the Mueller matrix and its subsequent inverse analysis via the polar decomposition approach. The derived medium polarization parameters, namely, linear retardance (δ), diattenuation (d), and depolarization coefficient (Δ), of the hydrogels showed interesting differences between the gels prepared by conventional free radical polymerization (FRP) and reversible addition-fragmentation chain transfer polymerization (RAFT) and also between dry and swollen state. The effect of temperature, cross-linking density, and polymerization technique employed to synthesize hydrogel on deswelling kinetics was systematically studied via conventional gravimetry and corroborated further with the corresponding Mueller matrix derived quantitative polarimetry characteristics (δ, d, and Δ). The RAFT gels exhibited higher swelling ratio and swelling-induced optical anisotropy compared to FRP gels and also deswelled faster at 30 °C. On the contrary, at 45 °C, deswelling was significantly retarded for the RAFT gels due to formation of a skin layer, which was confirmed and quantified via the enhanced diattenuation and depolarization parameters.

  13. Using guitar learning to probe the Action Observation Network's response to visuomotor familiarity.

    Science.gov (United States)

    Gardner, Tom; Aglinskas, Aidas; Cross, Emily S

    2017-08-01

    Watching other people move elicits engagement of a collection of sensorimotor brain regions collectively termed the Action Observation Network (AON). An extensive literature documents more robust AON responses when observing or executing familiar compared to unfamiliar actions, as well as a positive correlation between amplitude of AON response and an observer's familiarity with an observed or executed movement. On the other hand, emerging evidence shows patterns of AON activity counter to these findings, whereby in some circumstances, unfamiliar actions lead to greater AON engagement than familiar actions. In an attempt to reconcile these conflicting findings, some have proposed that the relationship between AON response amplitude and action familiarity is nonlinear in nature. In the present study, we used an elaborate guitar training intervention to probe the relationship between movement familiarity and AON engagement during action execution and action observation tasks. Participants underwent fMRI scanning while executing one set of guitar sequences with a scanner-compatible bass guitar and observing a second set of sequences. Participants then acquired further physical practice or observational experience with half of these stimuli outside the scanner across 3 days. Participants then returned for an identical scanning session, wherein they executed and observed equal numbers of familiar (trained) and unfamiliar (untrained) guitar sequences. Via region of interest analyses, we extracted activity within AON regions engaged during both scanning sessions, and then fit linear, quadratic and cubic regression models to these data. The data best support the cubic regression models, suggesting that the response profile within key sensorimotor brain regions associated with the AON respond to action familiarity in a nonlinear manner. Moreover, by probing the subjective nature of the prediction error signal, we show results consistent with a predictive coding account of

  14. Anisotropy across Superplume Boundaries

    Science.gov (United States)

    Cottaar, S.; Romanowicz, B. A.

    2011-12-01

    Sdiff data sets are presented for paths that run parallel to the African and the Pacific superplume boundaries. Objective clustering of waveforms illustrates sharp changes across these boundaries. The African plume shows a sharp offset in travel times in the SHdiff phase, while a more gradual offset towards slower arrivals is seen in the case of the Pacific superplume. Additionally, Pdiff phases display no offset around the African plume and a weak one around the Pacific plume. Here we focus mainly on another striking feature observed in both cases: outside of the superplume the Sdiff particle motion is strongly elliptical, but becomes linear within the superplume (first noticed by To et al. 2005 in the African superplume case). For the African plume we argue that these observations of delayed SV at large distances (~120 degrees) are indicative of the occurrence of azimuthal anisotropy. The SV arrivals have similar polarity as SH, opposite from what their radiation pattern predicts. Azimuthal anisotropy causes SH energy to be converted to SV (Maupin, 1994), explaining the travel time, polarity and amplitude. Forward modeling through different isotropic and anisotropic models supports this statement, although there are trade-offs between direction and magnitude of azimuthal anisotropy. The strong elliptical particle motions are also observed outside the Pacific plume, but at shorter distances (95-105 degrees). Elliptical motions can occur in the absence of anisotropy when strong velocity deviations or layering occurs close to the CMB, which, based on velocity profiles with depth in global tomographic models would be more likely within the superplume rather than on the fast side. The elliptical particle motions here can be modelled with a simple transverse isotropic model with VSH>VSV, but azimuthal anisotropy cannot be ruled out. The complexities within the Pacific superplume, including strong amplitude drop and existence of a post-cursor, are likely caused by an

  15. EMIC wave scale size in the inner magnetosphere: Observations from the dual Van Allen Probes

    Science.gov (United States)

    Blum, L. W.; Bonnell, J. W.; Agapitov, O.; Paulson, K.; Kletzing, C.

    2017-02-01

    Estimating the spatial scales of electromagnetic ion cyclotron (EMIC) waves is critical for quantifying their overall scattering efficiency and effects on thermal plasma, ring current, and radiation belt particles. Using measurements from the dual Van Allen Probes in 2013-2014, we characterize the spatial and temporal extents of regions of EMIC wave activity and how these depend on local time and radial distance within the inner magnetosphere. Observations are categorized into three types—waves observed by only one spacecraft, waves measured by both spacecraft simultaneously, and waves observed by both spacecraft with some time lag. Analysis reveals that dayside (and H+ band) EMIC waves more frequently span larger spatial areas, while nightside (and He+ band) waves are more often localized but can persist many hours. These investigations give insight into the nature of EMIC wave generation and support more accurate quantification of their effects on the ring current and outer radiation belt.

  16. Second harmonic poloidal waves observed by Van Allen Probes in the dusk-midnight sector

    International Nuclear Information System (INIS)

    Min, Kyungguk; Takahashi, Kazue; Ukhorskiy, Aleksandr Y.; Manweiler, Jerry W.; Spence, Harlan E.

    2017-01-01

    This paper presents observations of ultralow-frequency (ULF) waves from Van Allen Probes. The event that generated the ULF waves occurred 2 days after a minor geomagnetic storm during a geomagnetically quiet time. Narrowband pulsations with a frequency of about 7 mHz with moderate amplitudes were registered in the premidnight sector when Probe A was passing through an enhanced density region near geosynchronous orbit. Probe B, which passed through the region earlier, did not detect the narrowband pulsations but only broadband noise. Despite the single-spacecraft measurements, we were able to determine various wave properties. We find that the observed waves are a second harmonic poloidal mode propagating westward with an azimuthal wave number estimated to be ~100; the magnetic field fluctuations have a finite compressional component due to small but finite plasma beta (~0.1); the energetic proton fluxes in the energy ranging from above 10 keV to about 100 keV exhibit pulsations with the same frequency as the poloidal mode and energy-dependent phase delays relative to the azimuthal component of the electric field, providing evidence for drift-bounce resonance; and the second harmonic poloidal mode may have been excited via the drift-bounce resonance mechanism with free energy fed by the inward radial gradient of ~80 keV protons. Here, we show that the wave active region is where the plume overlaps the outer edge of ring current and suggest that this region can have a wide longitudinal extent near geosynchronous orbit.

  17. Probing extra dimension through gravitational wave observations of compact binaries and their electromagnetic counterparts

    Science.gov (United States)

    Yu, Hao; Gu, Bao-Min; Huang, Fa Peng; Wang, Yong-Qiang; Meng, Xin-He; Liu, Yu-Xiao

    2017-02-01

    The future gravitational wave (GW) observations of compact binaries and their possible electromagnetic counterparts may be used to probe the nature of the extra dimension. It is widely accepted that gravitons and photons are the only two completely confirmed objects that can travel along null geodesics in our four-dimensional space-time. However, if there exist extra dimensions and only GWs can propagate freely in the bulk, the causal propagations of GWs and electromagnetic waves (EMWs) are in general different. In this paper, we study null geodesics of GWs and EMWs in a five-dimensional anti-de Sitter space-time in the presence of the curvature of the universe. We show that for general cases the horizon radius of GW is longer than EMW within equal time. Taking the GW150914 event detected by the Advanced Laser Interferometer Gravitational-Wave Observatory and the X-ray event detected by the Fermi Gamma-ray Burst Monitor as an example, we study how the curvature k and the constant curvature radius l affect the horizon radii of GW and EMW in the de Sitter and Einstein-de Sitter models of the universe. This provides an alternative method for probing extra dimension through future GW observations of compact binaries and their electromagnetic counterparts.

  18. Observations Directly Linking Relativistic Electron Microbursts to Whistler Mode Chorus: Van Allen Probes and FIREBIRD II

    Science.gov (United States)

    Breneman, A. W.; Crew, A.; Sample, J.; Klumpar, D.; Johnson, A.; Agapitov, O.; Shumko, M.; Turner, D. L.; Santolik, O.; Wygant, J. R.; Cattell, C. A.; Thaller, S.; Blake, B.; Spence, H.; Kletzing, C. A.

    2017-11-01

    We present observations that provide the strongest evidence yet that discrete whistler mode chorus packets cause relativistic electron microbursts. On 20 January 2016 near 1944 UT the low Earth orbiting CubeSat Focused Investigations of Relativistic Electron Bursts: Intensity, Range, and Dynamics (FIREBIRD II) observed energetic microbursts (near L = 5.6 and MLT = 10.5) from its lower limit of 220 keV, to 1 MeV. In the outer radiation belt and magnetically conjugate, Van Allen Probe A observed rising-tone, lower band chorus waves with durations and cadences similar to the microbursts. No other waves were observed. This is the first time that chorus and microbursts have been simultaneously observed with a separation smaller than a chorus packet. A majority of the microbursts do not have the energy dispersion expected for trapped electrons bouncing between mirror points. This confirms that the electrons are rapidly (nonlinearly) scattered into the loss cone by a coherent interaction with the large amplitude (up to ˜900 pT) chorus. Comparison of observed time-averaged microburst flux and estimated total electron drift shell content at L = 5.6 indicate that microbursts may represent a significant source of energetic electron loss in the outer radiation belt.

  19. Gradual Diffusion and Punctuated Phase Space Density Enhancements of Highly Relativistic Electrons: Van Allen Probes Observations

    Science.gov (United States)

    Baker, D. N.; Jaynes, A. N.; Li, X.; Henderson, M. G.; Kanekal, S. G.; Reeves, G. D.; Spence, H. E.; Claudepierre, S. G.; Fennell, J. F.; Hudson, M. K.

    2014-01-01

    The dual-spacecraft Van Allen Probes mission has provided a new window into mega electron volt (MeV) particle dynamics in the Earth's radiation belts. Observations (up to E (is) approximately 10MeV) show clearly the behavior of the outer electron radiation belt at different timescales: months-long periods of gradual inward radial diffusive transport and weak loss being punctuated by dramatic flux changes driven by strong solar wind transient events. We present analysis of multi-MeV electron flux and phase space density (PSD) changes during March 2013 in the context of the first year of Van Allen Probes operation. This March period demonstrates the classic signatures both of inward radial diffusive energization and abrupt localized acceleration deep within the outer Van Allen zone (L (is) approximately 4.0 +/- 0.5). This reveals graphically that both 'competing' mechanisms of multi-MeV electron energization are at play in the radiation belts, often acting almost concurrently or at least in rapid succession.

  20. C3H2 observations as a diagnostic probe for molecular clouds

    Science.gov (United States)

    Avery, L. W.

    1986-01-01

    Recently the three-membered ring molecule, cyclopropenylidene, C3H2, has been identified in the laboratory and detected in molecular clouds by Thaddeus, Vrtilek and Gottlieb (1985). This molecule is wide-spread throughout the Galaxy and has been detected in 25 separate sources including cold dust clouds, circumstellar envelopes, HII regions, and the spiral arms observed against the Cas supernova remnant. In order to evaluate the potential of C3H2 as a diagnostic probe for molecular clouds, and to attempt to identify the most useful transitions, statistical equilibrium calculations were carried out for the lowest 24 levels of the ortho species and the lowest 10 levels of the para species. Many of the sources observed by Matthews and Irvine (1985) show evidence of being optically thick in the 1(10)-1(01) line. Consequently, the effects of radiative trapping should be incorporated into the equilibrium calculations. This was done using the Large Velocity Gradient approximation for a spherical cloud of uniform density. Some results of the calculations for T(K)=10K are given. Figures are presented which show contours of the logarithm of the ratio of peak line brightness temperatures for ortho-para pairs of lines at similar frequencies. It appears that the widespread nature of C3H2, the relatively large strength of its spectral lines, and their sensitivity to density and molecular abundance combine to make this a useful molecule for probing physical conditions in molecular clouds. The 1(10)-1(01) and 2(20)-2(11) K-band lines may be especially useful in this regard because of the ease with which they are observed and their unusual density-dependent emission/absorption properties.

  1. Van Allen Probes observations of unusually low frequency whistler mode waves observed in association with moderate magnetic storms: Statistical study.

    Science.gov (United States)

    Cattell, C A; Breneman, A W; Thaller, S A; Wygant, J R; Kletzing, C A; Kurth, W S

    2015-09-28

    We show the first evidence for locally excited chorus at frequencies below 0.1  f ce (electron cyclotron frequency) in the outer radiation belt. A statistical study of chorus during geomagnetic storms observed by the Van Allen Probes found that frequencies are often dramatically lower than expected. The frequency at peak power suddenly stops tracking the equatorial 0.5  f ce and f / f ce decreases rapidly, often to frequencies well below 0.1  f ce (in situ and mapped to equator). These very low frequency waves are observed both when the satellites are close to the equatorial plane and at higher magnetic latitudes. Poynting flux is consistent with generation at the equator. Wave amplitudes can be up to 20 to 40 mV/m and 2 to 4 nT. We conclude that conditions during moderate to large storms can excite unusually low frequency chorus, which is resonant with more energetic electrons than typical chorus, with critical implications for understanding radiation belt evolution.

  2. Counting probe

    International Nuclear Information System (INIS)

    Matsumoto, Haruya; Kaya, Nobuyuki; Yuasa, Kazuhiro; Hayashi, Tomoaki

    1976-01-01

    Electron counting method has been devised and experimented for the purpose of measuring electron temperature and density, the most fundamental quantities to represent plasma conditions. Electron counting is a method to count the electrons in plasma directly by equipping a probe with the secondary electron multiplier. It has three advantages of adjustable sensitivity, high sensitivity of the secondary electron multiplier, and directional property. Sensitivity adjustment is performed by changing the size of collecting hole (pin hole) on the incident front of the multiplier. The probe is usable as a direct reading thermometer of electron temperature because it requires to collect very small amount of electrons, thus it doesn't disturb the surrounding plasma, and the narrow sweep width of the probe voltage is enough. Therefore it can measure anisotropy more sensitively than a Langmuir probe, and it can be used for very low density plasma. Though many problems remain on anisotropy, computer simulation has been carried out. Also it is planned to provide a Helmholtz coil in the vacuum chamber to eliminate the effect of earth magnetic field. In practical experiments, the measurement with a Langmuir probe and an emission probe mounted to the movable structure, the comparison with the results obtained in reverse magnetic field by using a Helmholtz coil, and the measurement of ionic sound wave are scheduled. (Wakatsuki, Y.)

  3. Van Allen Probes observations of oxygen cyclotron harmonic waves in the inner magnetosphere

    Science.gov (United States)

    Usanova, M.; Malaspina, D.; Jaynes, A. N.; Bruder, R.; Mann, I. R.; Wygant, J. R.; Ergun, R.

    2016-12-01

    Waves with frequencies in the vicinity of the oxygen cyclotron frequency and its harmonics have been regularly observed on the Van Allen Probes satellites during geomagnetic storms. We focus on properties of these waves and present events from the main phase of two storms on November 1, 2012 and March 17, 2013 and associated dropouts of few MeV electron fluxes. They are electromagnetic, in the frequency range 0.5 - several Hz, and amplitude 0.1- a few nT in magnetic and 0.1- a few mV/m in electric field, with both the wave velocity and the Poynting vector directed almost parallel to the background magnetic field. These properties are very similar to those of electromagnetic ion cyclotron (EMIC) waves, which are believed to contribute to loss of ring current ions and radiation belt electrons and therefore can be also important for inner magnetosphere dynamics.

  4. Generation of EMIC Waves Observed by Van Allen Probes at Low L-shells of Earth's Magnetosphere

    Science.gov (United States)

    Gamayunov, K. V.; Zhang, J.; Saikin, A.; Rassoul, H.

    2017-12-01

    In a multi-ion magnetospheric plasma, where the major species are H+, He+, and O+, the He-band of electromagnetic ion cyclotron (EMIC) waves is the dominant band observed in the inner magnetosphere, and waves are generally quasi-field-aligned inside the geostationary orbit. Almost all the satellite-based studies of EMIC waves before Van Allen Probes, however, have not reported waves below L 3.5. There is probably only one exception from the Akebono satellite where both the H-band and He-band EMIC waves were observed at L 2. The situation has changed dramatically after two Van Allen Probes spacecraft were launched on 30 August, 2012, and many EMIC wave events have been observed below L=4. The Van Allen Probes observations confirm that the He-band of EMIC waves is a dominant band in the inner magnetosphere, but the observation of the He-band waves below L=4 is a new and quite unexpected result compared to our knowledge about EMIC waves before the Van Allen Probes era. In addition, observations show that almost all the He-band EMIC waves are linearly polarized in the region L field, and energetic ion distribution functions will be taken from the Van Allen Probes observations during the EMIC wave event to calculate growth rates of EMIC waves. We will then identify the energetic ions responsible for instability, frequencies and normals generated, and physical mechanism of instability.

  5. Van Allen Probes Observations of Second Harmonic Poloidal Standing Alfvén Waves

    Science.gov (United States)

    Takahashi, Kazue; Oimatsu, Satoshi; Nosé, Masahito; Min, Kyungguk; Claudepierre, Seth G.; Chan, Anthony; Wygant, John; Kim, Hyomin

    2018-01-01

    Long-lasting second-harmonic poloidal standing Alfvén waves (P2 waves) were observed by the twin Van Allen Probes (Radiation Belt Storm Probes, or RBSP) spacecraft in the noon sector of the plasmasphere, when the spacecraft were close to the magnetic equator and had a small azimuthal separation. Oscillations of proton fluxes at the wave frequency (˜10 mHz) were also observed in the energy (W) range 50-300 keV. Using the unique RBSP orbital configuration, we determined the phase delay of magnetic field perturbations between the spacecraft with a 2nπ ambiguity. We then used finite gyroradius effects seen in the proton flux oscillations to remove the ambiguity and found that the waves were propagating westward with an azimuthal wave number (m) of ˜-200. The phase of the proton flux oscillations relative to the radial component of the wave magnetic field progresses with W, crossing 0 (northward moving protons) or 180° (southward moving protons) at W ˜ 120 keV. This feature is explained by drift-bounce resonance (mωd ˜ ωb) of ˜120 keV protons with the waves, where ωd and ωb are the proton drift and bounce frequencies. At lower energies, the proton phase space density (FH+) exhibits a bump-on-tail structure with ∂FH+/∂W>0 occurring in the 1-10 keV energy range. This FH+ is unstable and can excite P2 waves through bounce resonance (ω ˜ ωb), where ω is the wave frequency.

  6. Late time CMB anisotropies constrain mini-charged particles

    Energy Technology Data Exchange (ETDEWEB)

    Burrage, C.; Redondo, J.; Ringwald, A. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Jaeckel, J. [Univ. of Durham, Inst. for Particle Physics Phenomenology (United Kingdom)

    2009-09-15

    Observations of the temperature anisotropies induced as light from the CMB passes through large scale structures in the late universe are a sensitive probe of the interactions of photons in such environments. In extensions of the Standard Model which give rise to mini-charged particles, photons propagating through transverse magnetic fields can be lost to pair production of such particles. Such a decrement in the photon flux would occur as photons from the CMB traverse the magnetic fields of galaxy clusters. Therefore late time CMB anisotropies can be used to constrain the properties of mini- charged particles. We outline how this test is constructed, and present new constraints on mini-charged particles from observations of the Sunyaev-Zel'dovich effect in the Coma cluster. (orig.)

  7. Supernovae anisotropy power spectrum

    Energy Technology Data Exchange (ETDEWEB)

    Ghodsi, Hoda; Baghram, Shant [Department of Physics, Sharif University of Technology, P.O. Box 11155-9161, Tehran (Iran, Islamic Republic of); Habibi, Farhang, E-mail: h.ghodsi@mehr.sharif.ir, E-mail: baghram@sharif.edu, E-mail: habibi@lal.in2p3.fr [LAL-IN2P3/CNRS, BP 34, 91898 Orsay Cedex (France)

    2017-10-01

    We contribute another anisotropy study to this field of research using Type Ia supernovae (SNe Ia). In this work, we utilise the power spectrum calculation method and apply it to both the current SNe Ia data and simulation. Using the Union2.1 data set at all redshifts, we compare the spectrum of the residuals of the observed distance moduli to that expected from an isotropic universe affected by the Union2.1 observational uncertainties at low multipoles. Through this comparison we find a dipolar anisotropy with tension of less that 2σ towards l = 171° ± 21° and b = −26° ± 28° which is mainly induced by anisotropic spatial distribution of the SNe with z > 0.2 rather than being a cosmic effect. Furthermore, we find a tension of ∼ 4σ at ℓ = 4 between the two spectra. Our simulations are constructed with the characteristics of the upcoming surveys like the Large Synoptic Survey Telescope (LSST), which shall bring us the largest SNe Ia collection to date. We make predictions for the amplitude of a possible dipolar anisotropy that would be detectable by future SNe Ia surveys.

  8. Statistical Features of EMIC Waves Observed on Van Allen Probes in the Inner Magnetosphere

    Science.gov (United States)

    Lee, D. Y.; Roh, S. J.; Cho, J.; Shin, D. K.; Hwang, J.; Kim, K. C.; Kurth, W. S.; Kletzing, C.; Wygant, J. R.; Thaller, S. A.

    2015-12-01

    Electromagnetic ion cyclotron (EMIC) waves are one of the key plasma waves that can affect charged particle dynamics in the Earth's inner magnetosphere. Knowledge of global distribution of the EMIC waves is critical for accurately assessing the significance of its interaction with charged particles. With the Van Allen Probes EMFISIS observations, we have surveyed EMIC events for ~2.5 years period. We have identified well-defined, banded wave activities only, as distinguished from broad band wave activities. We have obtained global distribution of occurrence of the identified waves with distinction between H- and He-bands. We compare it with previous observations such as THEMIS and CRRES. For the identified events we have drawn all the basic wave properties including wave frequency, polarization, wave normal angle. In addition, we have distinguished the EMIC events that occur inside the plasmasphere and at the plasmapause from those outside the plasmasphere. Finally, we have tested solar wind and geomagnetic dependence of the wave events. We give discussions about implications of these observations on wave generation mechanism and interaction with radiation belt electrons.

  9. Anisotropy in the direction of cosmic-muon bundles observed at sea level in the Northern hemisphere

    International Nuclear Information System (INIS)

    Bressi, G.; Calligarich, E.; Cambiaghi, M.; Dolfini, R.; Genoni, M.; Gigli Berzolari, A.; Lanza, A.; Liguori, G.; Mauri, F.; Piazzoli, A.; Bini, C.; Conversi, M.; Zorzi, G. De; Gauzzi, P.; Massa, F.; Zanello, D.; Cardarelli, R.; Santonico, R.; Terrani, M.

    1990-01-01

    Parallel muon bundles have been observed utilizing a tracking calorimeter of flash chambers and lead-iron absorbers. The right ascension distribution of about 13 000 events collected in 27.8 days of run is anisotropic. Its first Fourier harmonic has an amplitude of (4.9 ± 1.2). 10 -2 and a phase of (236 ± 13) 0

  10. Flow stress anisotropy in aluminium

    DEFF Research Database (Denmark)

    Juul Jensen, D.; Hansen, N.

    1990-01-01

    tension as a function of the angle between the tensile axis and the rolling direction. Textures were determined by neutron diffraction, and Taylor M-factors were calculated. The microstructures were studied by TEM. It was found that the flow stress varies significantly with orientation both at low......The plastic anisotropy of cold-rolled high purity aluminum (99.996%) and commercially pure aluminum (99.6%) has been investigated. Sample parameters were the initial grain size and the degree of plastic strain (ϵ stresses (0.2% offset) were measured at room temperature by uniaxial...... and high strains. It is shown that for most experimental conditions, texture effects alone cannot explain the observed anisotropy, and microstructural anisotropy effects have to be taken into account. In those cases, a correlation between the microstructural anisotropy and the development of microbands...

  11. Application of New Chorus Wave Model from Van Allen Probe Observations in Earth's Radiation Belt Modeling

    Science.gov (United States)

    Wang, D.; Shprits, Y.; Spasojevic, M.; Zhu, H.; Aseev, N.; Drozdov, A.; Kellerman, A. C.

    2017-12-01

    In situ satellite observations, theoretical studies and model simulations suggested that chorus waves play a significant role in the dynamic evolution of relativistic electrons in the Earth's radiation belts. In this study, we developed new wave frequency and amplitude models that depend on Magnetic Local Time (MLT)-, L-shell, latitude- and geomagnetic conditions indexed by Kp for upper-band and lower-band chorus waves using measurements from the Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) instrument onboard the Van Allen Probes. Utilizing the quasi-linear full diffusion code, we calculated corresponding diffusion coefficients in each MLT sector (1 hour resolution) for upper-band and lower-band chorus waves according to the new developed wave models. Compared with former parameterizations of chorus waves, the new parameterizations result in differences in diffusion coefficients that depend on energy and pitch angle. Utilizing obtained diffusion coefficients, lifetime of energetic electrons is parameterized accordingly. In addition, to investigate effects of obtained diffusion coefficients in different MLT sectors and under different geomagnetic conditions, we performed simulations using four-dimensional Versatile Electron Radiation Belt simulations and validated results against observations.

  12. Understanding the Mechanisms of Radiation Belt Dropouts Observed by Van Allen Probes

    Science.gov (United States)

    Xiang, Zheng; Tu, Weichao; Li, Xinlin; Ni, Binbin; Morley, S. K.; Baker, D. N.

    2017-10-01

    To achieve a better understanding of the dominant loss mechanisms for the rapid dropouts of radiation belt electrons, three distinct radiation belt dropout events observed by Van Allen Probes are comprehensively investigated. For each event, observations of the pitch angle distribution of electron fluxes and electromagnetic ion cyclotron (EMIC) waves are analyzed to determine the effects of atmospheric precipitation loss due to pitch angle scattering induced by EMIC waves. Last closed drift shells (LCDS) and magnetopause standoff position are obtained to evaluate the effects of magnetopause shadowing loss. Evolution of electron phase space density (PSD) versus L* profiles and the μ and K (first and second adiabatic invariants) dependence of the electron PSD drops are calculated to further analyze the dominant loss mechanisms at different L*. Our findings suggest that these radiation belt dropouts can be classified into distinct classes in terms of dominant loss mechanisms: magnetopause shadowing dominant, EMIC wave scattering dominant, and combination of both mechanisms. Different from previous understanding, our results show that magnetopause shadowing can deplete electrons at L* 4. Compared to the magnetopause standoff position, it is more reliable to use LCDS to evaluate the impact of magnetopause shadowing. The evolution of electron PSD versus L* profile and the μ, K dependence of electron PSD drops can provide critical and credible clues regarding the mechanisms responsible for electron losses at different L* over the outer radiation belt.

  13. Near?Earth injection of MeV electrons associated with intense dipolarization electric fields: Van Allen Probes observations

    OpenAIRE

    Dai, Lei; Wang, Chi; Duan, Suping; He, Zhaohai; Wygant, John R.; Cattell, Cynthia A.; Tao, Xin; Su, Zhenpeng; Kletzing, Craig; Baker, Daniel N.; Li, Xinlin; Malaspina, David; Blake, J. Bernard; Fennell, Joseph; Claudepierre, Seth

    2015-01-01

    Abstract Substorms generally inject tens to hundreds of keV electrons, but intense substorm electric fields have been shown to inject MeV electrons as well. An intriguing question is whether such MeVelectron injections can populate the outer radiation belt. Here we present observations of a substorm injection of MeV electrons into the inner magnetosphere. In the premidnight sector at L ? 5.5, Van Allen Probes (Radiation Belt Storm Probes)?A observed a large dipolarization electric field (50?m...

  14. Cross-scale observations of the 2015 St. Patrick's day storm: THEMIS, Van Allen Probes, and TWINS

    Science.gov (United States)

    Goldstein, J.; Angelopoulos, V.; De Pascuale, S.; Funsten, H. O.; Kurth, W. S.; LLera, K.; McComas, D. J.; Perez, J. D.; Reeves, G. D.; Spence, H. E.; Thaller, S. A.; Valek, P. W.; Wygant, J. R.

    2017-01-01

    We present cross-scale magnetospheric observations of the 17 March 2015 (St. Patrick's Day) storm, by Time History of Events and Macroscale Interactions during Substorms (THEMIS), Van Allen Probes (Radiation Belt Storm Probes), and Two Wide-angle Imaging Neutral-atom Spectrometers (TWINS), plus upstream ACE/Wind solar wind data. THEMIS crossed the bow shock or magnetopause 22 times and observed the magnetospheric compression that initiated the storm. Empirical models reproduce these boundary locations within 0.7 RE. Van Allen Probes crossed the plasmapause 13 times; test particle simulations reproduce these encounters within 0.5 RE. Before the storm, Van Allen Probes measured quiet double-nose proton spectra in the region of corotating cold plasma. About 15 min after a 0605 UT dayside southward turning, Van Allen Probes captured the onset of inner magnetospheric convection, as a density decrease at the moving corotation-convection boundary (CCB) and a steep increase in ring current (RC) proton flux. During the first several hours of the storm, Van Allen Probes measured highly dynamic ion signatures (numerous injections and multiple spectral peaks). Sustained convection after ˜1200 UT initiated a major buildup of the midnight-sector ring current (measured by RBSP A), with much weaker duskside fluxes (measured by RBSP B, THEMIS a and THEMIS d). A close conjunction of THEMIS d, RBSP A, and TWINS 1 at 1631 UT shows good three-way agreement in the shapes of two-peak spectra from the center of the partial RC. A midstorm injection, observed by Van Allen Probes and TWINS at 1740 UT, brought in fresh ions with lower average energies (leading to globally less energetic spectra in precipitating ions) but increased the total pressure. The cross-scale measurements of 17 March 2015 contain significant spatial, spectral, and temporal structure.

  15. Van Allen Probes observations of whistler-mode chorus with long-lived oscillating tones

    Science.gov (United States)

    Gao, Zhonglei; Su, Zhenpeng; Chen, Lunjin; Zheng, Huinan; Wang, Yuming; Wang, Shui

    2017-06-01

    Whistler-mode chorus plays an important role in the radiation belt electron dynamics. In the frequency-time spectrogram, chorus often appears as a hiss-like band and/or a series of short-lived (up to ˜1 s) discrete elements. Here we present some rarely reported chorus emissions with long-lived (up to 25 s) oscillating tones observed by the Van Allen Probes in the dayside (MLT ˜9-14) midlatitude (|MLAT|>15°) region. An oscillating tone can behave either regularly or irregularly and can even transform into a nearly constant tone (with a relatively narrow frequency sweep range). We suggest that these highly coherent oscillating tones were generated naturally rather than being related to some artificial VLF transmitters. Possible scenarios for the generation of the oscillating tone chorus are as follows: (1) being nonlinearly triggered by the accompanying hiss-like bands or (2) being caused by the modulation of the wave source. The details of the generation and evolution of such a long-lived oscillating tone chorus need to be investigated both theoretically and experimentally in the future.

  16. High-spatial-resolution electron density measurement by Langmuir probe for multi-point observations using tiny spacecraft

    Science.gov (United States)

    Hoang, H.; Røed, K.; Bekkeng, T. A.; Trondsen, E.; Clausen, L. B. N.; Miloch, W. J.; Moen, J. I.

    2017-11-01

    A method for evaluating electron density using a single fixed-bias Langmuir probe is presented. The technique allows for high-spatio-temporal resolution electron density measurements, which can be effectively carried out by tiny spacecraft for multi-point observations in the ionosphere. The results are compared with the multi-needle Langmuir probe system, which is a scientific instrument developed at the University of Oslo comprising four fixed-bias cylindrical probes that allow small-scale plasma density structures to be characterized in the ionosphere. The technique proposed in this paper can comply with the requirements of future small-sized spacecraft, where the cost-effectiveness, limited space available on the craft, low power consumption and capacity for data-links need to be addressed. The first experimental results in both the plasma laboratory and space confirm the efficiency of the new approach. Moreover, detailed analyses on two challenging issues when deploying the DC Langmuir probe on a tiny spacecraft, which are the limited conductive area of the spacecraft and probe surface contamination, are presented in the paper. It is demonstrated that the limited conductive area, depending on applications, can either be of no concern for the experiment or can be resolved by mitigation methods. Surface contamination has a small impact on the performance of the developed probe.

  17. Flow stress anisotropy

    DEFF Research Database (Denmark)

    Winther, G.

    1996-01-01

    stress Variation in the rolling plane, which may be as high as 20%, are presented. The traditional Taylor model is applied to the data to account for the effect of texture. However, texture effects alone are not enough to explain all of the observed anisotropy. New models which take the combined effects...... of texture and deformation microstructure into account are presented. The models are based on the Taylor and Sachs models but modified with an anisotropic critical shear stress to account for the effect of the microstructure. The agreement between experimental data and model predictions is definitely better...

  18. Evaporation Anisotropy of Forsterite

    Science.gov (United States)

    Ozawa, K.; Nagahara, H.; Morioka, M.

    1996-03-01

    Evaporation anisotropy of a synthetic single crystal of forsterite was investigated by high temperature vacuum experiments. The (001), (010), and (001) surfaces show microstructures characteristic for each surface. Obtained overall linear evaporation rates for the (001), (010), and (001) surfaces are ~17, ~7, and ~22 mm/hour, and the intrinsic evaporation rates, obtained by the change in surface microstructures, are ~10, ~4.5, and ~35 mm/hour, respectively. The difference between the intrinsic evaporation rates and overall rates can be regarded as contribution of dislocation, which is notable for the (100) and (010) surfaces and insignificant for the (001) surface. This is consistent with observed surface microstructures.

  19. Laboratory seismic anisotropy in mylonites

    Science.gov (United States)

    Almqvist, B. S. G.; Herwegh, M.; Hirt, A. M.; Ebert, A.; Linckens, J.; Precigout, J.; Leiss, B.; Walter, J. M.; Burg, J.-P.

    2012-04-01

    Tectonic strain is often accommodated along narrow zones in the Earth's crust and upper mantle, and these high-strain zones represent an important mechanical and rheological component in geodynamics. In outcrop we observe the intense deformation along and across these structures. But at depth, in the mid and lower crust, and in the mantle, we are dependent on geophysical methods for analysis of structures, such as seismic reflection and refraction surveys. A natural progression has therefore been to understand the remote geophysical signal in terms of laboratory ultrasonic pulse transmission measurements on rock cores, collected in the field or from borehole drill core. Here we first present a brief review that consider key studies in the area of laboratory seismic measurements in strongly anisotropic rocks, ranging from calcite mylonites to metapelites. In the second part we focus attention on ongoing research projects targetting laboratory seismic anisotropy in mylonitized rocks, and associated challenges. Measurements of compressional (P) and shear (S) waves were made at high confining pressure (up to 5 kbar). Mineral texture analysis was performed with electron backscatter diffraction (EBSD) and neutron texture diffraction to determine crystallographic preferred orientation (CPO). So-called "rock-recipe" models are used to calculate seismic anisotropy, which consider the elastic properties of minerals that constitutes the rock, and their respective CPO. However, the outcome of such models do not always simply correspond to the measured seismic anisotropy. Differences are attributed to several factors, such as grain boundaries, mineral microstructures including shape-preferred orientation (SPO), micro-cracks and pores, and grain-scale stress-strain conditions. We highlight the combination of these factors in case studies on calcite and peridotite mylonites. In calcite mylonites, sampled in the Morcles nappe shear zone, the measured seismic anisotropy generally

  20. Elastic anisotropy of crystals

    Directory of Open Access Journals (Sweden)

    Christopher M. Kube

    2016-09-01

    Full Text Available An anisotropy index seeks to quantify how directionally dependent the properties of a system are. In this article, the focus is on quantifying the elastic anisotropy of crystalline materials. Previous elastic anisotropy indices are reviewed and their shortcomings discussed. A new scalar log-Euclidean anisotropy measure AL is proposed, which overcomes these deficiencies. It is based on a distance measure in a log-Euclidean space applied to fourth-rank elastic tensors. AL is an absolute measure of anisotropy where the limiting case of perfect isotropy yields zero. It is a universal measure of anisotropy applicable to all crystalline materials. Specific examples of strong anisotropy are highlighted. A supplementary material provides an anisotropy table giving the values of AL for 2,176 crystallite compounds.

  1. A Modified Version of Taylor’s Hypothesis for Solar Probe Plus Observations

    Science.gov (United States)

    Klein, Kristopher G.; Perez, Jean C.; Verscharen, Daniel; Mallet, Alfred; Chandran, Benjamin D. G.

    2015-03-01

    The Solar Probe Plus (SPP) spacecraft will explore the near-Sun environment, reaching heliocentric distances less than 10 {{R}⊙ }. Near Earth, spacecraft measurements of fluctuating velocities and magnetic fields taken in the time domain are translated into information about the spatial structure of the solar wind via Taylor’s “frozen turbulence” hypothesis. Near the perihelion of SPP, however, the solar-wind speed is comparable to the Alfvén speed, and Taylor’s hypothesis in its usual form does not apply. In this paper, we show that under certain assumptions, a modified version of Taylor’s hypothesis can be recovered in the near-Sun region. We consider only the transverse, non-compressive component of the fluctuations at length scales exceeding the proton gyroradius, and we describe these fluctuations using an approximate theoretical framework developed by Heinemann and Olbert. We show that fluctuations propagating away from the Sun in the plasma frame obey a relation analogous to Taylor’s hypothesis when {{V}sc,\\bot }\\gg {{z}-} and {{z}+}\\gg {{z}-}, where {{V}sc,\\bot } is the component of the spacecraft velocity perpendicular to the mean magnetic field and {{{\\boldsymbol{z}} }+} ({{{\\boldsymbol{z}} }-}) is the Elsasser variable corresponding to transverse, non-compressive fluctuations propagating away from (toward) the Sun in the plasma frame. Observations and simulations suggest that, in the near-Sun solar wind, the above inequalities are satisfied and {{{\\boldsymbol{z}} }+} fluctuations account for most of the fluctuation energy. The modified form of Taylor’s hypothesis that we derive may thus make it possible to characterize the spatial structure of the energetically dominant component of the turbulence encountered by SPP.

  2. The work function of doped polyaniline nanoparticles observed by Kelvin probe force microscopy

    International Nuclear Information System (INIS)

    Park, Jinsung; Jang, Kuewhan; Na, Sungsoo; Bang, Doyeon; Haam, Seungjoo; Yang, Jaemoon

    2012-01-01

    The work function of polyaniline nanoparticles in the emeraldine base state was determined by Kelvin probe force microscopy to be ∼270 meV higher than that of similar nanoparticles in the emeraldine salt state. Normal tapping mode atomic force microscopy could not be used to distinguish between the particles due to their similar morphologies and sizes. Moreover, other potential measurement systems, such as using zeta potentials, were not suitable for the measurement of surface charges of doped nanoparticles due to their encapsulation by interfering chemical groups. Kelvin probe force microscopy can be used to overcome these limitations and unambiguously distinguish between the bare and doped polyaniline nanoparticles. (paper)

  3. Observations of the azimuthal dependence of normal mode coupling below 4 mHz at the South Pole and its nearby stations: Insights into the anisotropy beneath the Transantarctic Mountains

    Science.gov (United States)

    Hu, Xiao Gang

    2016-08-01

    Normal mode coupling pair 0S26-0T26 and 0S27-0T27 are significantly present at the South Pole station QSPA after the 2011/03/11 Mw9.1 Tohoku earthquake. In an attempt to determine the mechanisms responsible for the coupling pairs, I first investigate mode observations at 43 stations distributed along the polar great-circle path for the earthquake and observations at 32 Antarctic stations. I rule out the effect of Earth's rotation as well as the effect of global large-scale lateral heterogeneity, but argue instead for the effect of small-scale local azimuthal anisotropy in a depth extent about 300 km. The presence of quasi-Love waveform in 2-5 mHz at QSPA and its nearby stations confirms the predication. Secondly, I analyze normal mode observations at the South Pole location after 28 large earthquakes from 1998 to 2015. The result indicates that the presence of the mode coupling is azimuthal dependent, which is related to event azimuths in -46° to -18°. I also make a comparison between the shear-wave splitting measurements of previous studies and the mode coupling observations of this study, suggesting that their difference can be explained by a case that the anisotropy responsible for the mode coupling is not just below the South Pole location but located below region close to the Transantarctic Mountains (TAM). Furthermore, more signals of local azimuthal anisotropy in normal-mode observations at QSPA and SBA, such as coupling of 0S12-0T11 and vertical polarization anomaly for 0T10, confirms the existence of deep anisotropy close to TAM, which may be caused by asthenospheric mantle flow and edge convection around cratonic keel of TAM.

  4. Observation of long-range elliptic azimuthal anisotropies in √s = 13 and 2.76 TeV pp collisions with the ATLAS detector

    Czech Academy of Sciences Publication Activity Database

    Aad, G.; Abbott, B.; Abdallah, J.; Chudoba, Jiří; Havránek, Miroslav; Hejbal, Jiří; Jakoubek, Tomáš; Kepka, Oldřich; Kupčo, Alexander; Kůs, Vlastimil; Lokajíček, Miloš; Lysák, Roman; Marčišovský, Michal; Mikeštíková, Marcela; Němeček, Stanislav; Penc, Ondřej; Šícho, Petr; Staroba, Pavel; Svatoš, Michal; Taševský, Marek; Vrba, Václav

    2016-01-01

    Roč. 116, č. 17 (2016), 1-20, č. článku 172301. ISSN 0031-9007 Institutional support: RVO:68378271 Keywords : CERN LHC Coll * factorization * enhancement * correlation * long-range * elliptic flow * modulation * anisotropy * tracks: multiplicity Subject RIV: BF - Elementary Particles and High Energy Physics Impact factor: 8.462, year: 2016

  5. Energetic electron precipitation associated with pulsating aurora: EISCAT and Van Allen Probe observations

    Czech Academy of Sciences Publication Activity Database

    Miyoshi, Y.; Oyama, S.; Saito, S.; Kurita, S.; Fujiwara, H.; Kataoka, R.; Ebihara, Y.; Kletzing, C.; Reeves, G.; Santolík, Ondřej; Clilverd, M.; Rodger, C. J.; Turunen, E.; Tsuchiya, F.

    2015-01-01

    Roč. 120, č. 4 (2015), s. 2754-2766 ISSN 2169-9380 Institutional support: RVO:68378289 Keywords : pulsating aurora * EISCAT * Van Allen Probes * pitch angle scattering Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 3.318, year: 2015 http://onlinelibrary.wiley.com/doi/10.1002/2014JA020690/abstract

  6. Probing Extreme-density Matter with Gravitational-wave Observations of Binary Neutron Star Merger Remnants

    Energy Technology Data Exchange (ETDEWEB)

    Radice, David [Institute for Advanced Study, 1 Einstein Drive, Princeton, NJ 08540 (United States); Bernuzzi, Sebastiano [Department of Mathematical, Physical and Computer Sciences, University of Parma, I-43124 Parma (Italy); Pozzo, Walter Del [Dipartimento di Fisica “Enrico Fermi,” Università di Pisa, Pisa I-56127 (Italy); Roberts, Luke F. [NSCL/FRIB and Department of Physics and Astronomy, Michigan State University, 640 S Shaw Lane, East Lansing, MI 48824 (United States); Ott, Christian D. [TAPIR, Walter Burke Institute for Theoretical Physics, California Institute of Technology, 1200 E. California Boulevard, Pasadena, CA 91125 (United States)

    2017-06-20

    We present a proof-of-concept study, based on numerical-relativity simulations, of how gravitational waves (GWs) from neutron star merger remnants can probe the nature of matter at extreme densities. Phase transitions and extra degrees of freedom can emerge at densities beyond those reached during the inspiral, and typically result in a softening of the equation of state (EOS). We show that such physical effects change the qualitative dynamics of the remnant evolution, but they are not identifiable as a signature in the GW frequency, with the exception of possible black hole formation effects. The EOS softening is, instead, encoded in the GW luminosity and phase and is in principle detectable up to distances of the order of several megaparsecs with advanced detectors and up to hundreds of megaparsecs with third-generation detectors. Probing extreme-density matter will require going beyond the current paradigm and developing a more holistic strategy for modeling and analyzing postmerger GW signals.

  7. Anisotropy in the deep Earth

    Science.gov (United States)

    Romanowicz, Barbara; Wenk, Hans-Rudolf

    2017-08-01

    Seismic anisotropy has been found in many regions of the Earth's interior. Its presence in the Earth's crust has been known since the 19th century, and is due in part to the alignment of anisotropic crystals in rocks, and in part to patterns in the distribution of fractures and pores. In the upper mantle, seismic anisotropy was discovered 50 years ago, and can be attributed for the most part, to the alignment of intrinsically anisotropic olivine crystals during large scale deformation associated with convection. There is some indication for anisotropy in the transition zone, particularly in the vicinity of subducted slabs. Here we focus on the deep Earth - the lower mantle and core, where anisotropy is not yet mapped in detail, nor is there consensus on its origin. Most of the lower mantle appears largely isotropic, except in the last 200-300 km, in the D″ region, where evidence for seismic anisotropy has been accumulating since the late 1980s, mostly from shear wave splitting measurements. Recently, a picture has been emerging, where strong anisotropy is associated with high shear velocities at the edges of the large low shear velocity provinces (LLSVPs) in the central Pacific and under Africa. These observations are consistent with being due to the presence of highly anisotropic MgSiO3 post-perovskite crystals, aligned during the deformation of slabs impinging on the core-mantle boundary, and upwelling flow within the LLSVPs. We also discuss mineral physics aspects such as ultrahigh pressure deformation experiments, first principles calculations to obtain information about elastic properties, and derivation of dislocation activity based on bonding characteristics. Polycrystal plasticity simulations can predict anisotropy but models are still highly idealized and neglect the complex microstructure of polyphase aggregates with strong and weak components. A promising direction for future progress in understanding the origin of seismic anisotropy in the deep mantle

  8. Substorm Injected Energetic Electrons and Ions Deeply into the Inner Magnetosphere Observed by BD-IES and Van Allan Probes

    Science.gov (United States)

    Zong, Qiugang

    2017-04-01

    When substorm injections are observed simultaneously with multiple spacecraft, they help elucidate potential mechanisms for particle transport and energization, a topic of great importance for understanding and modeling the magnetosphere. In the present paper, by using the data return from the BeiDa- IES (BD-IES) instrument onboard an inclined (55◦) geosynchronous orbit (IGSO) satellite together with geo-transfer orbit (GTO) Van Allen Probe A&B satellite, we analysis a substorm injection event occurred on Oct 16, 2015. During the substorm injection, the IES onboard IGSO is outbound while both Van Allen Probe A&B satellites are inbound. This configuration of multiple satellite trajectories provides a unique opportunity to investigate the inward and outward radial propagation of the substorm injection simultaneously. This substorm as indicated by AE/AL indices is closely related an IMF/solar wind discontinuity with a sharp change in the IMF Bz direction (northward turning). The innermost signature of this substorm injection has been detected by the Van Allen Probes A & B at L 3.7. The outermost signature, observed by the BD-IES, is found to be at L 10. This indicated that this substorm have a rather global effect rather than just a local effect. Further, we suggest that the electric fields carried by fast-mode compressional waves around the substorm injection are the most likely mechanism candidate for the injection signatures of electrons observed in the innermost and outermost inner magnetosphere.

  9. Radial Propagation of Magnetospheric Substorm Injected Energetic Electrons Observed by BD-IES and Van Allan Probes

    Science.gov (United States)

    Zong, Q.

    2016-12-01

    When substorm injections are observed simultaneously with multiple spacecraft, they help elucidate potential mechanisms for particle transport and energization, a topic of great importance for understanding and modeling the magnetosphere. In the present paper, by using the data return from the BeiDa- IES (BD-IES) instrument onboard an inclined (55°) geosynchronous orbit (IGSO) satellite together with geo-transfer orbit (GTO) Van Allen Probe A&B satellite, we analysis a substorm injection event occurred on Oct 16, 2015. During the substorm injection, the IES onboard IGSO is outbound while both Van Allen Probe A&B satellites are inbound. This configuration of multiple satellite trajectories provides a unique opportunity to investigate the inward and outward radial propagation of the substorm injection simultaneously. This substorm as indicated by AE/AL indices is closely related an IMF/solar wind discontinuity with a sharp change in the IMF Bz direction (northward turning). The innermost signature of this substorm injection has been detected by the Van Allen Probes A & B at L 3.7. The outermost signature, observed by the BD-IES, is found to be at L 10. This indicated that this substorm have a rather global effect rather than just a local effect. Further, we suggest that the electric fields carried by fast-mode compressional waves around the substorm injection are the most likely mechanism candidate for the injection signatures of electrons observed in the innermost and outermost inner magnetosphere.

  10. Observation of a large-scale anisotropy in the arrival directions of cosmic rays above 8 x 10.sup.18./sup. eV

    Czech Academy of Sciences Publication Activity Database

    Aab, A.; Abreu, P.; Aglietta, M.; Blažek, Jiří; Boháčová, Martina; Chudoba, Jiří; Ebr, Jan; Juryšek, Jakub; Mandát, Dušan; Palatka, Miroslav; Pech, Miroslav; Prouza, Michael; Řídký, Jan; Schovánek, Petr; Trávníček, Petr; Vícha, Jakub

    2017-01-01

    Roč. 357, č. 6357 (2017), s. 1266-1270 ISSN 0036-8075 R&D Projects: GA MŠk LM2015038; GA MŠk LG15014; GA ČR(CZ) GA14-17501S Institutional support: RVO:68378271 Keywords : cosmic rays * Pierre Auger Observatory * ultrahigh energy * large-scale anisotropy Subject RIV: BF - Elementary Particles and High Energy Physics OBOR OECD: Particles and field physics Impact factor: 37.205, year: 2016

  11. High-field magnetization curve of random-anisotropy amorphous magnet: Observation of a crossover and link to structural short-range order

    Science.gov (United States)

    Filippi, J.; Amaral, V. S.; Barbara, B.

    1991-08-01

    High-field magnetization curves of the series of amorphous alloys DyxGd1-xNi have been measured up to 15 tesla and interpreted in the framework of the theory of Chudnovsky et al. The results show several features (high-field crossovers, correlation volume of local-anisotropy directions, ferromagnetic correlation length) all consistent with each other and in agreement with theoretical predictions.

  12. High-field magnetization curve of random-anisotropy amorphous magnet: Observation of a crossover and link to structural short-range order

    International Nuclear Information System (INIS)

    Filippi, J.; Amaral, V.S.; Barbara, B.

    1991-01-01

    High-field magnetization curves of the series of amorphous alloys Dy x Gd 1-x Ni have been measured up to 15 tesla and interpreted in the framework of the theory of Chudnovsky et al. The results show several features (high-field crossovers, correlation volume of local-anisotropy directions, ferromagnetic correlation length) all consistent with each other and in agreement with theoretical predictions

  13. Coherent evolution of parahydrogen induced polarisation using laser pump, NMR probe spectroscopy: Theoretical framework and experimental observation.

    Science.gov (United States)

    Halse, Meghan E; Procacci, Barbara; Henshaw, Sarah-Louise; Perutz, Robin N; Duckett, Simon B

    2017-05-01

    We recently reported a pump-probe method that uses a single laser pulse to introduce parahydrogen (p-H 2 ) into a metal dihydride complex and then follows the time-evolution of the p-H 2 -derived nuclear spin states by NMR. We present here a theoretical framework to describe the oscillatory behaviour of the resultant hyperpolarised NMR signals using a product operator formalism. We consider the cases where the p-H 2 -derived protons form part of an AX, AXY, AXYZ or AA'XX' spin system in the product molecule. We use this framework to predict the patterns for 2D pump-probe NMR spectra, where the indirect dimension represents the evolution during the pump-probe delay and the positions of the cross-peaks depend on the difference in chemical shift of the p-H 2 -derived protons and the difference in their couplings to other nuclei. The evolution of the NMR signals of the p-H 2 -derived protons, as well as the transfer of hyperpolarisation to other NMR-active nuclei in the product, is described. The theoretical framework is tested experimentally for a set of ruthenium dihydride complexes representing the different spin systems. Theoretical predictions and experimental results agree to within experimental error for all features of the hyperpolarised 1 H and 31 P pump-probe NMR spectra. Thus we establish the laser pump, NMR probe approach as a robust way to directly observe and quantitatively analyse the coherent evolution of p-H 2 -derived spin order over micro-to-millisecond timescales. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  14. Coherent evolution of parahydrogen induced polarisation using laser pump, NMR probe spectroscopy: Theoretical framework and experimental observation

    Science.gov (United States)

    Halse, Meghan E.; Procacci, Barbara; Henshaw, Sarah-Louise; Perutz, Robin N.; Duckett, Simon B.

    2017-05-01

    We recently reported a pump-probe method that uses a single laser pulse to introduce parahydrogen (p-H2) into a metal dihydride complex and then follows the time-evolution of the p-H2-derived nuclear spin states by NMR. We present here a theoretical framework to describe the oscillatory behaviour of the resultant hyperpolarised NMR signals using a product operator formalism. We consider the cases where the p-H2-derived protons form part of an AX, AXY, AXYZ or AA‧XX‧ spin system in the product molecule. We use this framework to predict the patterns for 2D pump-probe NMR spectra, where the indirect dimension represents the evolution during the pump-probe delay and the positions of the cross-peaks depend on the difference in chemical shift of the p-H2-derived protons and the difference in their couplings to other nuclei. The evolution of the NMR signals of the p-H2-derived protons, as well as the transfer of hyperpolarisation to other NMR-active nuclei in the product, is described. The theoretical framework is tested experimentally for a set of ruthenium dihydride complexes representing the different spin systems. Theoretical predictions and experimental results agree to within experimental error for all features of the hyperpolarised 1H and 31P pump-probe NMR spectra. Thus we establish the laser pump, NMR probe approach as a robust way to directly observe and quantitatively analyse the coherent evolution of p-H2-derived spin order over micro-to-millisecond timescales.

  15. Higher-order anisotropies in the Buda-Lund model: Disentangling flow and density field anisotropies

    Energy Technology Data Exchange (ETDEWEB)

    Loekoes, Sandor [Eoetvoes Lorand University, Budapest (Hungary); Csanad, Mate [Eoetvoes Lorand University, Budapest (Hungary); Stony Brook University, Stony Brook, NY (United States); Tomasik, Boris [Univerzita Mateja Bela, Banska Bystrica (Slovakia); Czech Technical University in Prague, FNSPE, Prague (Czech Republic); Csoergo, Tamas [Wigner RCP, Budapest (Hungary); KRF, Gyoengyoes (Hungary)

    2016-10-15

    The Buda-Lund hydro model describes an expanding ellipsoidal fireball, and fits the observed elliptic flow and oscillating HBT radii successfully. Due to fluctuations in energy depositions, the fireball shape however fluctuates on an event-by-event basis. The transverse plane asymmetry can be translated into a series of multipole anisotropy coefficients. These anisotropies then result in measurable momentum-space anisotropies, to be measured with respect to their respective symmetry planes. In this paper we detail an extension of the Buda-Lund model to multipole anisotropies and investigate the resulting flow coefficients and oscillations of HBT radii. (orig.)

  16. Near-Earth injection of MeV electrons associated with intense dipolarization electric fields: Van Allen Probes observations.

    Science.gov (United States)

    Dai, Lei; Wang, Chi; Duan, Suping; He, Zhaohai; Wygant, John R; Cattell, Cynthia A; Tao, Xin; Su, Zhenpeng; Kletzing, Craig; Baker, Daniel N; Li, Xinlin; Malaspina, David; Blake, J Bernard; Fennell, Joseph; Claudepierre, Seth; Turner, Drew L; Reeves, Geoffrey D; Funsten, Herbert O; Spence, Harlan E; Angelopoulos, Vassilis; Fruehauff, Dennis; Chen, Lunjin; Thaller, Scott; Breneman, Aaron; Tang, Xiangwei

    2015-08-16

    Substorms generally inject tens to hundreds of keV electrons, but intense substorm electric fields have been shown to inject MeV electrons as well. An intriguing question is whether such MeVelectron injections can populate the outer radiation belt. Here we present observations of a substorm injection of MeV electrons into the inner magnetosphere. In the premidnight sector at L ∼ 5.5, Van Allen Probes (Radiation Belt Storm Probes)-A observed a large dipolarization electric field (50 mV/m) over ∼40 s and a dispersionless injection of electrons up to ∼3 MeV. Pitch angle observations indicated betatron acceleration of MeV electrons at the dipolarization front. Corresponding signals of MeV electron injection were observed at LANL-GEO, THEMIS-D, and GOES at geosynchronous altitude. Through a series of dipolarizations, the injections increased the MeV electron phase space density by 1 order of magnitude in less than 3 h in the outer radiation belt ( L > 4.8). Our observations provide evidence that deep injections can supply significant MeV electrons.

  17. Dispersion relations of density fluctuations observed by heavy ion beam probe in the TEXT tokamak

    International Nuclear Information System (INIS)

    Ross, D.W.

    1990-09-01

    Wave numbers as functions of frequency for density fluctuations in the core of the TEXT tokamak are measured in Heavy Ion Beam Probe experiments by analyzing the relative phases of signals originating from nearby points in the plasma. The adjacent points are typically 2 cm apart, with their relative orientation (δr, δθ) depending on position (r,θ). for angular frequencies ω ≤ 10 6 /s the signals are quite coherent, leading to reasonably well-defined ''dispersion relations.'' These do not correspond to known modes of the drift wave type, i.e., ballooning or slab-like electron drift waves or ion temperature gradient modes. The effect of finite sample volume size does not significantly alter this conclusion. 25 refs., 6 figs., 3 tabs

  18. Statistical distribution of EMIC wave spectra: Observations from Van Allen Probes

    Science.gov (United States)

    Zhang, X.-J.; Li, W.; Thorne, R. M.; Angelopoulos, V.; Bortnik, J.; Kletzing, C. A.; Kurth, W. S.; Hospodarsky, G. B.

    2016-12-01

    It has been known that electromagnetic ion cyclotron (EMIC) waves can precipitate ultrarelativistic electrons through cyclotron resonant scattering. However, the overall effectiveness of this mechanism has yet to be quantified, because it is difficult to obtain the global distribution of EMIC waves that usually exhibit limited spatial presence. We construct a statistical distribution of EMIC wave frequency spectra and their intensities based on Van Allen Probes measurements from September 2012 to December 2015. Our results show that as the ratio of plasma frequency over electron gyrofrequency increases, EMIC wave power becomes progressively dominated by the helium band. There is a pronounced dawn-dusk asymmetry in the wave amplitude and the frequency spectrum. The frequency spectrum does not follow the commonly used single-peak Gaussian function. Incorporating these realistic EMIC wave frequency spectra into radiation belt models is expected to improve the quantification of EMIC wave scattering effects in ultrarelativistic electron dynamics.

  19. Using ACE Observations of Interplanetary Particles and Magnetic Fields as Possible Contributors to Variations Observed at Van Allen Probes during Major events in 2013

    Science.gov (United States)

    Armstrong, T. P.; Manweiler, J. W.; Gerrard, A. J.; Gkioulidou, M.; Lanzerotti, L. J.; Patterson, J. D.

    2013-12-01

    Observations from ACE EPAM including energy spectra of protons, helium, and oxygen will be prepared for coordinated use in estimating the direct and indirect access of energetic particles to inner and outer geomagnetic trapping zones. Complete temporal coverage from ACE at 12 seconds, 5 minutes, 17 minutes, hourly and daily cadences will be used to catalog interplanetary events arriving at Earth including interplanetary magnetic field sector boundaries, interplanetary shocks, and interplanetary coronal mass ejections, ICMEs. The first 6 months of 2013 have included both highly disturbed times, March 17 and May 22, and extended quiet periods of little or no variations. Among the specific questions that ACE and Van Allen Probes coordinated observations may aid in resolving are: 1. How much, if any, direct capture of interplanetary energetic particles occurs and what conditions account for it? 2. How much influence do interplanetary field and particle variations have on energization and/or loss of geomagnetically trapped populations? The poster will also present important links and describe methods and important details of access to numerically expressed ACE EPAM and Van Allen Probes RBSPICE observations that can be flexibly and easily accessed via the internet for student and senior researcher use.

  20. Probing features in inflaton potential and reionization history with future CMB space observations

    Science.gov (United States)

    Hazra, Dhiraj Kumar; Paoletti, Daniela; Ballardini, Mario; Finelli, Fabio; Shafieloo, Arman; Smoot, George F.; Starobinsky, Alexei A.

    2018-02-01

    We consider the prospects of probing features in the primordial power spectrum with future Cosmic Microwave Background (CMB) polarization measurements. In the scope of the inflationary scenario, such features in the spectrum can be produced by local non-smooth pieces in an inflaton potential (smooth and quasi-flat in general) which in turn may originate from fast phase transitions during inflation in other quantum fields interacting with the inflaton. They can fit some outliers in the CMB temperature power spectrum which are unaddressed within the standard inflationary ΛCDM model. We consider Wiggly Whipped Inflation (WWI) as a theoretical framework leading to improvements in the fit to the Planck 2015 temperature and polarization data in comparison with the standard inflationary models, although not at a statistically significant level. We show that some type of features in the potential within the WWI models, leading to oscillations in the primordial power spectrum that extend to intermediate and small scales can be constrained with high confidence (at 3σ or higher confidence level) by an instrument as the Cosmic ORigins Explorer (CORE). In order to investigate the possible confusion between inflationary features and footprints from the reionization era, we consider an extended reionization history with monotonic increase of free electrons with decrease in redshift. We discuss the present constraints on this model of extended reionization and future predictions with CORE. We also project, to what extent, this extended reionization can create confusion in identifying inflationary features in the data.

  1. Fluorescence anisotropy of kidney lipids and membranes of a hibernating mammal.

    Science.gov (United States)

    Montaudon, D; Robert, J; Canguilhem, B

    1986-04-01

    The fluorescence anisotropy of lipids and membranes isolated from kidneys of European hamsters (Cricetus cricetus L.) has been estimated using 1,6-diphenyl-1,3,5-hexatriene as a probe. We have compared in this study the results obtained for two critical periods for a hibernator: winter (torpid state), and summer (active state). The differences were of very low magnitude. A slight increase in anisotropy was noticed in the kidney lipids and microsomal membrane preparations from torpid animals. In contrast, a small decrease in anisotropy was observed in the microsomal lipid extracts of torpid animals. A difference in triglyceride content of winter and summer total kidney lipids was detected, as well as a difference in microsomal protein content between winter and summer membrane preparations. It is hypothesized that the latter observations may explain why the behavior of kidney total lipids and microsomal preparations were different from that presented by kidney microsomal lipids in respect to fluorescence anisotropy. Therefore, only a little, if any, homeoviscous adaptation is exhibited by kidney membranes during hibernation of this mammal.

  2. Van Allen Probe observations of EMIC wave propagation in the inner magnetosphere

    Science.gov (United States)

    Saikin, A.; Zhang, J.; Smith, C. W.; Spence, H. E.; Torbert, R. B.; Kletzing, C.; Wygant, J. R.

    2017-12-01

    This study examines the propagation of inner magnetosphere (L vector, , analysis on all observed EMIC wave events to determine the direction of propagation, with bi-directionally propagating EMIC waves indicating the presence of the EMIC wave source region. EMIC waves were considered bi-directional (i.e., in the source region) if at least two wave packets exhibited opposing flux components, and (W/km2), consistently for 60 seconds. Events not observed to have opposing flux components are considered unidirectional. EMIC wave events observed at relatively high magnetic latitudes, generally, are found to propagate away from the magnetic equator (i.e., unidirectional). Bi-directionally propagating EMIC waves are preferably observed at lower magnetic latitudes. The occurrence rate, spatial distribution, and the energy propagation angle of both unidirectionally and bi-directionally propagating EMIC waves are examined with respect to L, MLT, and MLAT.

  3. Seismic anisotropy - Introduction

    Czech Academy of Sciences Publication Activity Database

    Grechka, V.; Pšenčík, Ivan; Ravve, I.; Tsvankin, I.

    2017-01-01

    Roč. 82, č. 4 (2017), WAI-WAII ISSN 0016-8033 Institutional support: RVO:67985530 Keywords : seismic anisotropy Subject RIV: DC - Siesmology, Volcanology, Earth Structure OBOR OECD: Volcanology Impact factor: 2.391, year: 2016

  4. HI observations of low surface brightness galaxies : Probing low-density galaxies

    NARCIS (Netherlands)

    deBlok, WJG; McGaugh, SS; vanderHulst, JM

    1996-01-01

    We present Very Large Array (VLA) and Westerbork Synthesis Radio Telescope (WSRT) 21-cm HI observations of 19 late-type low surface brightness (LSB) galaxies. Our main findings are that these galaxies, as well as having low surface brightnesses, have low HI surface densities, about a factor of

  5. Probing the interstellar medium in early-type galaxies with Infrared Space Oberservatory observations

    Science.gov (United States)

    Malhotra, S.; Hollenbach, D.; Helou, D.; Silbermann, N.; Valjavec, E.; Rubin, R.; Dale, D.; Hunter, D.; Lu, N.; Lord, S.; hide

    2000-01-01

    Four IRAS-detected early-type galaxies were observed with the Infrared Space Observatory (ISO). With the exception of the 15 mu m image of NGC 1052, the mid-IR images of NGC 1052, NGC 1155, NGC 5866, and NGC 6958 at 4.5, 7, and 15 mu m show extended emission.

  6. Constraints on the symmetry energy from observational probes of the neutron star crust

    International Nuclear Information System (INIS)

    Newton, William G.; Hooker, Joshua; Gearheart, Michael; Fattoyev, Farrukh J.; Li, Bao-An; Murphy, Kyleah; Wen, De-Hua

    2014-01-01

    A number of observed phenomena associated with individual neutron star systems or neutron star populations find explanations in models in which the neutron star crust plays an important role. We review recent work examining the sensitivity to the slope of the symmetry energy L of such models, and constraints extracted on L from confronting them with observations. We focus on six sets of observations and proposed explanations: (i) The cooling rate of the neutron star in Cassiopeia A, confronting cooling models which include enhanced cooling in the nuclear pasta regions of the inner crust; (ii) the upper limit of the observed periods of young X-ray pulsars, confronting models of magnetic field decay in the crust caused by the high resistivity of the nuclear pasta layer; (iii) glitches from the Vela pulsar, confronting the paradigm that they arise due to a sudden recoupling of the crustal neutron superfluid to the crustal lattice after a period during which they were decoupled due to vortex pinning; (iv) the frequencies of quasi-periodic oscillations in the X-ray tail of light curves from giant flares from soft gamma-ray repeaters, confronting models of torsional crust oscillations; (v) the upper limit on the frequency to which millisecond pulsars can be spun-up due to accretion from a binary companion, confronting models of the r-mode instability arising above a threshold frequency determined in part by the viscous dissipation timescale at the crust-core boundary; and (vi) the observations of precursor electromagnetic flares a few seconds before short gamma-ray bursts, confronting a model of crust shattering caused by resonant excitation of a crustal oscillation mode by the tidal gravitational field of a companion neutron star just before merger. (orig.)

  7. Probing the Baryon Cycle of Galaxies with SPICA Mid- and Far-Infrared Observations

    Science.gov (United States)

    van der Tak, F. F. S.; Madden, S. C.; Roelfsema, P.; Armus, L.; Baes, M.; Bernard-Salas, J.; Bolatto, A.; Bontemps, S.; Bot, C.; Bradford, C. M.; Braine, J.; Ciesla, L.; Clements, D.; Cormier, D.; Fernández-Ontiveros, J. A.; Galliano, F.; Giard, M.; Gomez, H.; González-Alfonso, E.; Herpin, F.; Johnstone, D.; Jones, A.; Kaneda, H.; Kemper, F.; Lebouteiller, V.; De Looze, I.; Matsuura, M.; Nakagawa, T.; Onaka, T.; Pérez-González, P.; Shipman, R.; Spinoglio, L.

    2018-01-01

    The SPICA mid- and far-infrared telescope will address fundamental issues in our understanding of star formation and ISM physics in galaxies. A particular hallmark of SPICA is the outstanding sensitivity enabled by the cold telescope, optimised detectors, and wide instantaneous bandwidth throughout the mid- and far-infrared. The spectroscopic, imaging, and polarimetric observations that SPICA will be able to collect will help in clarifying the complex physical mechanisms which underlie the baryon cycle of galaxies. In particular, (i) the access to a large suite of atomic and ionic fine-structure lines for large samples of galaxies will shed light on the origin of the observed spread in star-formation rates within and between galaxies, (ii) observations of HD rotational lines (out to 10 Mpc) and fine structure lines such as [C ii] 158 μm (out to 100 Mpc) will clarify the main reservoirs of interstellar matter in galaxies, including phases where CO does not emit, (iii) far-infrared spectroscopy of dust and ice features will address uncertainties in the mass and composition of dust in galaxies, and the contributions of supernovae to the interstellar dust budget will be quantified by photometry and monitoring of supernova remnants in nearby galaxies, (iv) observations of far-infrared cooling lines such as [O i] 63 μm from star-forming molecular clouds in our Galaxy will evaluate the importance of shocks to dissipate turbulent energy. The paper concludes with requirements for the telescope and instruments, and recommendations for the observing strategy.

  8. Solvent induced supramolecular anisotropy in molecular gels

    Energy Technology Data Exchange (ETDEWEB)

    Rogers, Michael A., E-mail: mroger09@uoguelph.ca [Department of Food Science, University of Guelph, Guelph, Ontario, N3C3X9 (Canada); Corradini, Maria G. [Department of Food Science, University of Massachusetts Amherst, Amherst, MA, 01003 (United States); Emge, Thomas [Department of Chemistry and Biochemistry, Rutgers University, New Brunswick, NJ, 08901 (United States)

    2017-06-15

    Herein is the first report of solvent induced anisotropy in 12-hydroxystearic acid self-assembled fibrillar networks. Increasing the chain length of polar solvent, such as nitriles and ketones, tailored the anisotropy of the fibrillar aggregates. 12HSA molecular gels, comprised of alkanes, exhibited an isotropic fibrillar network irrespective of the alkane chain length. In polar solvents, anisotropy, observed using 2D powder x-ray diffraction profiles, is correlated to a fibrillar supramolecular morphologies in long chain nitriles and ketones while sphereulitic crystals are correlated to x-ray diffraction patterns with an isotropic scatter intensity in short chain ketones and nitriles. These changes directly modify the final physical properties of the gels. - Highlights: • 12-HSA self-assembles into crystalline supramolecular morphologies depending on the solvent. • Alkanes, short chain nitriles and ketones led to 12-HSA displaying supramolecular isotropy. • In long chain nitriles and ketones, 12-HSA displays supramolecular anisotropy.

  9. Solvent induced supramolecular anisotropy in molecular gels

    International Nuclear Information System (INIS)

    Rogers, Michael A.; Corradini, Maria G.; Emge, Thomas

    2017-01-01

    Herein is the first report of solvent induced anisotropy in 12-hydroxystearic acid self-assembled fibrillar networks. Increasing the chain length of polar solvent, such as nitriles and ketones, tailored the anisotropy of the fibrillar aggregates. 12HSA molecular gels, comprised of alkanes, exhibited an isotropic fibrillar network irrespective of the alkane chain length. In polar solvents, anisotropy, observed using 2D powder x-ray diffraction profiles, is correlated to a fibrillar supramolecular morphologies in long chain nitriles and ketones while sphereulitic crystals are correlated to x-ray diffraction patterns with an isotropic scatter intensity in short chain ketones and nitriles. These changes directly modify the final physical properties of the gels. - Highlights: • 12-HSA self-assembles into crystalline supramolecular morphologies depending on the solvent. • Alkanes, short chain nitriles and ketones led to 12-HSA displaying supramolecular isotropy. • In long chain nitriles and ketones, 12-HSA displays supramolecular anisotropy.

  10. Impact of atmospheric refraction: how deeply can we probe exo-earth's atmospheres during primary eclipse observations?

    International Nuclear Information System (INIS)

    Bétrémieux, Yan; Kaltenegger, Lisa

    2014-01-01

    Most models used to predict or fit exoplanet transmission spectra do not include all the effects of atmospheric refraction. Namely, the angular size of the star with respect to the planet can limit the lowest altitude, or highest density and pressure, probed during primary eclipses as no rays passing below this critical altitude can reach the observer. We discuss this geometrical effect of refraction for all exoplanets and tabulate the critical altitude, density, and pressure for an exoplanet identical to Earth with a 1 bar N 2 /O 2 atmosphere as a function of both the incident stellar flux (Venus, Earth, and Mars-like) at the top of the atmosphere and the spectral type (O5-M9) of the host star. We show that such a habitable exo-Earth can be probed to a surface pressure of 1 bar only around the coolest stars. We present 0.4-5.0 μm model transmission spectra of Earth's atmosphere viewed as a transiting exoplanet, and show how atmospheric refraction modifies the transmission spectrum depending on the spectral type of the host star. We demonstrate that refraction is another phenomenon that can potentially explain flat transmission spectra over some spectral regions.

  11. Variation of Radiation Belt Content Indices and total electron energy During Magnetic Storms Based On Van Allen Probe Observations

    Science.gov (United States)

    Xiong, Y.; Xie, L.; Chen, L.; Pu, Z.

    2017-12-01

    We investigate the variability of the RBC indices and total electron energy for varying energies within outer belt during 42 isolate magnetic storms based on the electron flux data from MagEIS and REPT onboard Van Allen Probe-A spacecraft. Van Allan Probes travel throughout the entire radiation belt twice during each orbit, providing an excellent opportunity to measure the electron's pitch angle distributions near the magnetic equatorial plane which is essential to calculate the RBC index accurately. Instead of assuming an isotropic electron pitch angle distribution which is widely used in previous studies, we develop a new and reliable technique to infer the equatorial pitch angle distributions based on the off-equator measurements. The statistic results show that the total electron energy in outer belt increase in 80% storms and has a positive correlation with median value of AE during recovery phase and minimum -Dst. The possibility of observing RBC depletion increase at high energies. The upper limit energy of RBC enhancement has a positive correlation with median value of AE and Vsw during recovery phase and a negative correlation with median value of Nsw during storm, which is consist of the balance of acceleration by chorus waves and loss by EMIC waves.

  12. New VLA Data Reconcile Galileo Probe and Ground-based Radio Observations of Ammonia in Jupiter's Atmosphere

    Science.gov (United States)

    De Pater, I.; Sault, R. J.; Butler, B. J.; deBoer, D.; Wong, M. H.

    2016-12-01

    Visible and near-infrared images of the giant planets reveal a multitude of clouds, ranging in size from tiny, hardly visible, features to giant storm systems, such as Jupiter's Great Red Spot and Oval BA. At radio wavelengths we can probe altitudes in Jupiter's atmosphere below these visible cloud layers. We used the upgraded Very Large Array to map this unexplored region down to 10 bar. We will present full radio maps at frequencies between 4 and 35 GHz, with typical spatial resolutions of order 1000-2000 km. We will show spectra and radiative transfer calculations of individual features, in particular 5-micron hot spots and ammonia-rich "plumes". A comparison with models shows that the plumes bring NH3 gas from deep atmospheric levels where the ammonia concentration is equal to the Galileo probe abundance, all the way up to high altitudes (P responsible for forming the 5-micron hot spots. Our maps are complementary to observations planned for Juno's microwave radiometer (MWR). MWR's field-of-view is tiny, 1000 km at the highest frequencies at perijove, and is limited to extremely narrow swaths of longitude; as such, our VLA maps will provide regional and global context at wavelengths overlapping with Juno MWR. Three maps at 8-12 GHz, at a spatial resolution of 1000 km, will be taken near Juno perijove passes in October 2016 and January 2017.

  13. SUNYAEV-ZEL'DOVICH EFFECT OBSERVATIONS OF STRONG LENSING GALAXY CLUSTERS: PROBING THE OVERCONCENTRATION PROBLEM

    International Nuclear Information System (INIS)

    Gralla, Megan B.; Gladders, Michael D.; Marrone, Daniel P.; Bayliss, Matthew; Carlstrom, John E.; Greer, Christopher; Hennessy, Ryan; Koester, Benjamin; Leitch, Erik; Sharon, Keren; Barrientos, L. Felipe; Bonamente, Massimiliano; Bulbul, Esra; Hasler, Nicole; Culverhouse, Thomas; Hawkins, David; Lamb, James; Gilbank, David G.; Joy, Marshall; Miller, Amber

    2011-01-01

    We have measured the Sunyaev-Zel'dovich (SZ) effect for a sample of 10 strong lensing selected galaxy clusters using the Sunyaev-Zel'dovich Array (SZA). The SZA is sensitive to structures on spatial scales of a few arcminutes, while the strong lensing mass modeling constrains the mass at small scales (typically <30''). Combining the two provides information about the projected concentrations of the strong lensing clusters. The Einstein radii we measure are twice as large as expected given the masses inferred from SZ scaling relations. A Monte Carlo simulation indicates that a sample randomly drawn from the expected distribution would have a larger median Einstein radius than the observed clusters about 3% of the time. The implied overconcentration has been noted in previous studies and persists for this sample, even when we take into account that we are selecting large Einstein radius systems, suggesting that the theoretical models still do not fully describe the observed properties of strong lensing clusters.

  14. Probing the low-stellar-mass domain with Kepler and APOGEE observations of eclipsing binaries

    Science.gov (United States)

    Prsa, Andrej; Hambleton, Kelly

    2018-01-01

    Observations of low-mass stars (M noise, shot noise, nuisance astrophysical signals (such as spots) and the full set of eclipsing binary parameters. The results are obtained within a probabilistic framework, with robust mass and radius uncertainties ~1-4%. We overplot the derived masses, radii and temperatures over evolutionary models and note stellar size bloating w.r.t. model predictions for both systems. This work has been funded by the NSF grant #1517460.

  15. Probing dark matter decay and annihilation with Fermi LAT observations of nearby galaxy clusters

    International Nuclear Information System (INIS)

    Huang, Xiaoyuan; Vertongen, Gilles; Weniger, Christoph

    2011-09-01

    Galaxy clusters are promising targets for indirect dark matter searches. Gamma-ray signatures from the decay or annihilation of dark matter particles inside these clusters could be observable with the Fermi Large Area Telescope (LAT). Based on three years of Fermi LAT gamma-ray data, we analyze the flux coming from eight nearby clusters individually as well as in a combined likelihood analysis. Concentrating mostly on signals from dark matter decay, we take into account uncertainties of the cluster masses as determined by X-ray observations and model the cluster emission with extended sources. We do not find significant emission from any of the considered clusters and present limits on the dark matter lifetime and annihilation cross-section. We compare our lifetime limits derived from cluster observations with the limits that can be obtained from the extragalactic gamma-ray background, and find that in case of hadronic decay the cluster limits become competitive at dark matter masses below a few hundred GeV. Finally, we show that in presence of dark matter substructures down to 10 -6 solar masses the limits on the dark matter annihilation cross-section could improve by a factor of a few hundred, possibly going down to the thermal cross-section of 3 x 10 -26 cm 3 s -1 for dark matter masses < or similar 150 GeV and annihilation into b anti b. As a direct application of our results, we derive limits on the lifetime of gravitino dark matter in scenarios with R-parity violation. Implications of these limits for the possible observation of long-lived superparticles at the LHC are discussed. (orig.)

  16. Probing dark matter decay and annihilation with Fermi LAT observations of nearby galaxy clusters

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Xiaoyuan [Chinese Academy of Sciences, Beijing (China). National Astronomical Observatories; Max-Planck-Institut fuer Physik, Muenchen (Germany); Vertongen, Gilles [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Institut d' Astrophysique de Paris, 75 - Paris (France); Weniger, Christoph [Max-Planck-Institut fuer Physik, Muenchen (Germany)

    2011-09-15

    Galaxy clusters are promising targets for indirect dark matter searches. Gamma-ray signatures from the decay or annihilation of dark matter particles inside these clusters could be observable with the Fermi Large Area Telescope (LAT). Based on three years of Fermi LAT gamma-ray data, we analyze the flux coming from eight nearby clusters individually as well as in a combined likelihood analysis. Concentrating mostly on signals from dark matter decay, we take into account uncertainties of the cluster masses as determined by X-ray observations and model the cluster emission with extended sources. We do not find significant emission from any of the considered clusters and present limits on the dark matter lifetime and annihilation cross-section. We compare our lifetime limits derived from cluster observations with the limits that can be obtained from the extragalactic gamma-ray background, and find that in case of hadronic decay the cluster limits become competitive at dark matter masses below a few hundred GeV. Finally, we show that in presence of dark matter substructures down to 10{sup -6} solar masses the limits on the dark matter annihilation cross-section could improve by a factor of a few hundred, possibly going down to the thermal cross-section of 3 x 10{sup -26} cm{sup 3}s{sup -1} for dark matter masses observation of long-lived superparticles at the LHC are discussed. (orig.)

  17. The evolution of interstellar medium mass probed by dust emission: Alma observations at z = 0.3-2

    International Nuclear Information System (INIS)

    Scoville, N.; Manohar, S.; Aussel, H.; Sheth, K.; Scott, K. S.; Sanders, D.; Ivison, R.; Pope, A.; Capak, P.; Vanden Bout, P.; Kartaltepe, J.; Robertson, B.; Lilly, S.

    2014-01-01

    The use of submillimeter dust continuum emission to probe the mass of interstellar dust and gas in galaxies is empirically calibrated using samples of local star-forming galaxies, Planck observations of the Milky Way, and high-redshift submillimeter galaxies. All of these objects suggest a similar calibration, strongly supporting the view that the Rayleigh-Jeans tail of the dust emission can be used as an accurate and very fast probe of the interstellar medium (ISM) in galaxies. We present ALMA Cycle 0 observations of the Band 7 (350 GHz) dust emission in 107 galaxies from z = 0.2 to 2.5. Three samples of galaxies with a total of 101 galaxies were stellar-mass-selected from COSMOS to have M * ≅ 10 11 M ☉ : 37 at z ∼ 0.4, 33 at z ∼ 0.9, and 31 at z = 2. A fourth sample with six infrared-luminous galaxies at z = 2 was observed for comparison with the purely mass-selected samples. From the fluxes detected in the stacked images for each sample, we find that the ISM content has decreased by a factor ∼6 from 1 to 2 × 10 10 M ☉ at both z = 2 and 0.9 down to ∼2 × 10 9 M ☉ at z = 0.4. The infrared-luminous sample at z = 2 shows a further ∼4 times increase in M ISM compared with the equivalent non-infrared-bright sample at the same redshift. The gas mass fractions are ∼2% ± 0.5%, 12% ± 3%, 14% ± 2%, and 53% ± 3% for the four subsamples (z = 0.4, 0.9, and 2 and infrared-bright galaxies).

  18. Dynamical transition in molecular glasses and proteins observed by spin relaxation of nitroxide spin probes and labels

    Science.gov (United States)

    Golysheva, Elena A.; Shevelev, Georgiy Yu.; Dzuba, Sergei A.

    2017-08-01

    In glassy substances and biological media, dynamical transitions are observed in neutron scattering that manifests itself as deviations of the translational mean-squared displacement, , of hydrogen atoms from harmonic dynamics. In biological media, the deviation occurs at two temperature intervals, at ˜100-150 K and at ˜170-230 K, and it is attributed to the motion of methyl groups in the former case and to the transition from harmonic to anharmonic or diffusive motions in the latter case. In this work, electron spin echo (ESE) spectroscopy—a pulsed version of electron paramagnetic resonance—is applied to study the spin relaxation of nitroxide spin probes and labels introduced in molecular glass former o-terphenyl and in protein lysozyme. The anisotropic contribution to the rate of the two-pulse ESE decay, ΔW, is induced by spin relaxation appearing because of restricted orientational stochastic molecular motion; it is proportional to τc, where is the mean-squared angle of reorientation of the nitroxide molecule around the equilibrium position and τc is the correlation time of reorientation. The ESE time window allows us to study motions with τc τc temperature dependence shows a transition near 240 K, which is in agreement with the literature data on . For spin probes of essentially different size, the obtained data were found to be close, which evidences that motion is cooperative, involving a nanocluster of several neighboring molecules. For the dry lysozyme, the τc values below 260 K were found to linearly depend on the temperature in the same way as it was observed in neutron scattering for . As spin relaxation is influenced only by stochastic motion, the harmonic motions seen in ESE must be overdamped. In the hydrated lysozyme, ESE data show transitions near 130 K for all nitroxides, near 160 K for the probe located in the hydration layer, and near 180 K for the label in the protein interior. For this system, the two latter transitions are not

  19. Density waves in Saturn's rings probed by radio and optical occultation - Observational tests of theory

    Science.gov (United States)

    Brophy, Thomas G.; Rosen, Paul A.

    1992-01-01

    A parallel examination is conducted of Voyager radio and photopolarimeter occultation observations of the Saturn A ring's density waves. The radio instrument waves exhibit an average -90 deg offset from the dynamical phase. A warping height of about 100-m amplitude can qualtitatively reproduce this phase shift, while preserving the overall model wave shape. These results may be profoundly relevant for satellite-ring torque calculations in Saturn's rings, given the deposition of all of the net torque of the standard model in the first wavelength.

  20. Probing ice mélange rheology with observations of fast motion during iceberg calving events

    Science.gov (United States)

    Amundson, J. M.; Peters, I.; Cassotto, R.; Darnell, K.; Fahnestock, M. A.; Zhang, W. W.

    2013-12-01

    Recent studies have suggested that ice mélange, a dense pack of icebergs and brash ice found in many fjords, can inhibit iceberg calving by transmitting stresses from fjord walls to glacier termini. However, the rheology of ice mélange is completely unknown, severely limiting our ability to estimate resistive forces from ice mélange and their impact on glacier stability. To improve our understanding of ice mélange rheology, we operated a terrestrial radar and high-rate time-lapse camera at Jakobshavn Isbrae, Greenland, in August 2012. Our observations indicate that during calving events (1) the kinetic energy of the mélange motion is about an order of magnitude smaller than the total energy released by the calving iceberg(s), thus supporting previous studies that suggested that most of the energy released during calving is rapidly dissipated into the water, (2) there is a compaction front that propagates down fjord and through the mélange at a rate that is an order of magnitude faster than the icebergs in the fjord, (3) the mélange typically experiences a fractional decrease in area of a few percentage, and (4) once activity at the terminus ceases, motion of the mélange decays exponentially before finally coming to an abrupt halt. These observations can be partially explained with a model adapted from previous work on granular mechanics.

  1. Probing the sign-changeable interaction between dark energy and dark matter with current observations

    Science.gov (United States)

    Guo, Juan-Juan; Zhang, Jing-Fei; Li, Yun-He; He, Dong-Ze; Zhang, Xin

    2018-03-01

    We consider the models of vacuum energy interacting with cold dark matter in this study, in which the coupling can change sigh during the cosmological evolution. We parameterize the running coupling b by the form b( a) = b 0 a+ b e(1- a), where at the early-time the coupling is given by a constant b e and today the coupling is described by another constant b 0. We explore six specific models with (i) Q = b( a) H 0 ρ 0, (ii) Q = b( a) H 0 ρ de, (iii) Q = b( a) H 0 ρ c, (iv) Q = b( a) Hρ 0, (v) Q = b( a) H ρ de, and (vi) Q = b( a) Hρ c. The current observational data sets we use to constrain the models include the JLA compilation of type Ia supernova data, the Planck 2015 distance priors data of cosmic microwave background observation, the baryon acoustic oscillations measurements, and the Hubble constant direct measurement. We find that, for all the models, we have b 0 0 at around the 1 σ level, and b 0 and b e are in extremely strong anti-correlation. Our results show that the coupling changes sign during the evolution at about the 1 σ level, i.e., the energy transfer is from dark matter to dark energy when dark matter dominates the universe and the energy transfer is from dark energy to dark matter when dark energy dominates the universe.

  2. Probing Vela pulsar down to 20 GeV with H.E.S.S. II observations

    Science.gov (United States)

    Djannati-Ataï, A.; Giavitto, G.; Holler, M.; Rudak, B.; Venter, C.; H.E.S.S. Collaboration

    2017-01-01

    Observations of the Vela pulsar (PSR B0833-45) with the High Energy Stereoscopic System phase II array (H.E.S.S. II) have resulted in a high-significance detection of its pulsed emission down to 20 GeV. The very low-energy threshold reconstruction and analysis methods developed specifically for the monoscopic mode are presented together with detailed comparison of the results obtained with five years of Fermi-LAT data. A very good agreement is obtained between the two instruments, thereby validating the overall analysis chain and the response model of the largest H.E.S.S. telescope (CT5). The high event statistics are used to probe the spectrum of PSR B0833-45 above 20 GeV.

  3. Probing quantum gravity using photons from a flare of the active galactic nucleus Markarian 501 observed by the MAGIC telescope

    CERN Document Server

    Albert, J; Anderhub, H; Antonelli, L A; Antoranz, P; Backes, M; Baixeras, C; Barrio, J A; Bartko, H; Bastieri, D; Becker, J K; Bednarek, W; Berger, K; Bernardini, E; Bigongiari, C; Biland, A; Bock, R K; Bordas, P; Bosch-Ramon, V; Bretz, T; Britvitch, I; Camara, M; Carmona, E; Chilingarian, A; Commichau, S; Contreras, J L; Cortina, J; Costado, M T; Covino, S; Dazzi, F; De Angelis, A; De Cea del Pozo, E; Delgado Mendez, C; de los Reyes, R; De Lotto, B; De Maria, M; De Sabata, F; Dominguez, A; Dorner, D; Doro, M; Errando, M; Fagiolini, M; Ferenc, D; Fernández, E; Firpo, R; Fonseca, M V; Font, L; Galante, N; García-López, R J; Garczarczyk, M; Gaug, M; Göbel, F; Hayashida, M; Herrero, A; Höhne, D; Hose, J; Hsu, C C; Huber, S; Jogler, T; Kranich, D; La Barbera, A; Laille, A; Leonardo, E; Lindfors, E; Lombardi, S; Longo, F; López, M; Lorenz, E; Majumdar, P; Maneva, G; Mankuzhiyil, N; Mannheim, K; Maraschi, L; Mariotti, M; Martínez, M; Mazin, D; Meucci, M; Meyer, M; Miranda, J M; Mirzoyan, R; Moles, M; Moralejo, A; Nieto, D; Nilsson, K; Ninkovic, J; Otte, N; Oya, I; Panniello, M; Paoletti, R; Paredes, J M; Pasanen, M; Pascoli, D; Pauss, F; Pegna, R; Pérez-Torres, M A; Persic, M; Peruzzo, L; Piccioli, A; Prada, F; Puchades, N; Raymers, A; Ribó, M; Rico, J; Rissi, M; Robert, A; Rügamer, S; Saggion, A; Saitô, T; Salvati, M; Sanchez-Conde, M; Sartori, P; Satalecka, K; Scalzotto, V; Scapin, V; Schmitt, R; Schweizer, T; Shayduk, M; Shinozaki, K; Sidro, N; Sierpowska-Bartosik, A; Sillanpää, A; Spanier, F; Stamerra, A; Stark, L S; Takalo, L; Tavecchio, F; Temnikov, P; Tescaro, D; Teshima, M; Tluczykont, M; Torres, D F; Turini, N; Vankov, H; Venturini, A; Vitale, V; Wagner, R M; Wittek, W; Zabalza, M; Zandanel, F; Zanin, R; Ellis, Jonathan Richard; Mavromatos, N E; Nanopoulos, D V; Sakharov, Alexander S; Sarkisyan-Grinbaum, E

    2008-01-01

    We use the timing of photons observed by the MAGIC gamma-ray telescope during a flare of the active galaxy Markarian 501 to probe a vacuum refractive index ~ 1-(E/M_QGn)^n, n = 1,2, that might be induced by quantum gravity. The peaking of the flare is found to maximize for quantum-gravity mass scales M_QG1 ~ 0.4x10^18 GeV or M_QG2 ~ 0.6x10^11 GeV, and we establish lower limits M_QG1 > 0.26x10^18 GeV or M_QG2 > 0.39x10^11 GeV at the 95% C.L. Monte Carlo studies confirm the MAGIC sensitivity to propagation effects at these levels. Thermal plasma effects in the source are negligible, but we cannot exclude the importance of some other source effect.

  4. Van Allen Probes observations of prompt MeV radiation belt electron acceleration in nonlinear interactions with VLF chorus

    Science.gov (United States)

    Foster, J. C.; Erickson, P. J.; Omura, Y.; Baker, D. N.; Kletzing, C. A.; Claudepierre, S. G.

    2017-01-01

    Prompt recovery of MeV (millions of electron Volts) electron populations in the poststorm core of the outer terrestrial radiation belt involves local acceleration of a seed population of energetic electrons in interactions with VLF chorus waves. Electron interactions during the generation of VLF rising tones are strongly nonlinear, such that a fraction of the relativistic electrons at resonant energies are trapped by waves, leading to significant nonadiabatic energy exchange. Through detailed examination of VLF chorus and electron fluxes observed by Van Allen Probes, we investigate the efficiency of nonlinear processes for acceleration of electrons to MeV energies. We find through subpacket analysis of chorus waveforms that electrons with initial energy of hundreds of keV to 3 MeV can be accelerated by 50 keV-200 keV in resonant interactions with a single VLF rising tone on a time scale of 10-100 ms.

  5. Probing the symmetry energy at low density using observable from neck fragmentation

    Directory of Open Access Journals (Sweden)

    De Filippo E.

    2014-03-01

    Full Text Available Semi-peripheral collisions of 64Ni + 124Sn in direct and inverse kinematics, at 35 A MeV incident energy, are studied to characterize the dynamical origin and align-ments properties of fragments emission at midrapidity. This emission is partly due to the fragmentation of a transient neck joining the projectile and target in the early stages of the reaction. Recently we exploited observable from neck fragmentation to constraint the density dependence of the symmetry energy. In this contribution we focus on the density evolution of the mid-rapidity source. An experimental survey is suggested to check if data are consistent with the formation of neck fragments in a dilute density region in contact with the projectile-like and target-like spectators at normal saturation density.

  6. Measurement of the thermopower anisotropy in iron arsenide

    Energy Technology Data Exchange (ETDEWEB)

    Fujii, T., E-mail: fujii@crc.u-tokyo.ac.jp [Cryogenic Research Center, the University of Tokyo, 2-11-16 Yayoi, Bunkyo, Tokyo 113-0032 (Japan); Shirachi, T. [Department of Applied Physics, the University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan); Asamitsu, A. [Cryogenic Research Center, the University of Tokyo, 2-11-16 Yayoi, Bunkyo, Tokyo 113-0032 (Japan); Department of Applied Physics, the University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan); Ashikaga Institute of Technology, 268-1 Omae, Ashikaga, Tochigi 326-8558 (Japan)

    2016-11-15

    Highlights: • In this study, in order to investigate the origin of the in-plane anisotropy, the in-plane anisotropy of the thermopower was measured for the detwined single crystals of BFe{sub 2}As{sub 2}. And, we found no anisotropy in the thermopower above T{sub AFO}, although there is a large anisotropy in the resistivity. This result gives evidence that the anisotropy in the resistivity arise from the anisotropy of the scattering time, and the energy dependence of the scattering time can be considered negligible. In the case of iron pnictides, the proposed orbital ordering more likely results in an anisotropy of electronic structure below T{sub AFO}, whereas the spin-nematic ordering leads to an anisotropy of electron scattering above T{sub AFO}. Therefore, our results suggest that nematicity above T{sub AFO} results from anisotropic magnetic scattering. - Abstract: We investigated the in-plane anisotropy of the thermopower and electrical resistivity on detwinned single crystals of BaFe{sub 2}As{sub 2}. The in-plane anisotropy of the resistivity was clearly observed far above the magnetostructural transition temperature T{sub AFO}. While, the thermopower showed the in-plane anisotropy only below T{sub AFO}. These results are associated with the different origin of the anisotropy above and below T{sub AFO}. Since the thermopower does not depend on the scattering time, the anisotropy of the resistivity above T{sub AFO} is considered to be due to the anisotropic scattering. On the other hand, the anisotropy in the thermopower below T{sub AFO} is ascribed to the reconstructed Fermi surface.

  7. Initial measurements of O-ion and He-ion decay rates observed from the Van Allen probes RBSPICE instrument.

    Science.gov (United States)

    Gerrard, Andrew; Lanzerotti, Louis; Gkioulidou, Matina; Mitchell, Donald; Manweiler, Jerry; Bortnik, Jacob; Keika, Kunihiro

    2014-11-01

    H-ion (∼45 keV to ∼600 keV), He-ion (∼65 keV to ∼520 keV), and O-ion (∼140 keV to ∼1130 keV) integral flux measurements, from the Radiation Belt Storm Probe Ion Composition Experiment (RBSPICE) instrument aboard the Van Allan Probes spacecraft B, are reported. These abundance data form a cohesive picture of ring current ions during the first 9 months of measurements. Furthermore, the data presented herein are used to show injection characteristics via the He-ion/H-ion abundance ratio and the O-ion/H-ion abundance ratio. Of unique interest to ring current dynamics are the spatial-temporal decay characteristics of the two injected populations. We observe that He-ions decay more quickly at lower L shells, on the order of ∼0.8 day at L shells of 3-4, and decay more slowly with higher L shell, on the order of ∼1.7 days at L shells of 5-6. Conversely, O-ions decay very rapidly (∼1.5 h) across all L shells. The He-ion decay time are consistent with previously measured and calculated lifetimes associated with charge exchange. The O-ion decay time is much faster than predicted and is attributed to the inclusion of higher-energy (> 500 keV) O-ions in our decay rate estimation. We note that these measurements demonstrate a compelling need for calculation of high-energy O-ion loss rates, which have not been adequately studied in the literature to date. We report initial observations of ring current ionsWe show that He-ion decay rates are consistent with theoryWe show that O-ions with energies greater than 500 keV decay very rapidly.

  8. Probing a steep EoS for dark energy with latest observations

    Science.gov (United States)

    Jaber, Mariana; Macorra, Axel de la

    2018-01-01

    We present a parametrization for the Dark Energy Equation of State "EoS" which has a rich structure, performing a transition at pivotal redshift zT between the present day value w0 to an early time wi =wa +w0 ≡ w(z ≫ 0) with a steepness given in terms of q parameter. The proposed parametrization is w =w0 +wa(z /zT) q /(1 +(z /zT)) q , with w0, wi, q and zT constant parameters. It reduces to the widely used EoS w =w0 +wa(1 - a) for zT = q = 1 . This transition is motivated by scalar field dynamics such as for example quintessence models. We study if a late time transition is favored by BAO measurements combined with local determination of H0 and information from the CMB. We find that our dynamical DE model allows to simultaneously fit H0 from local determinations and Planck CMB measurements, alleviating the tension obtained in a ΛCDM model. We obtain a smaller χ2 in our DE model than in ΛCDM showing that a dynamical DE is preferred with a reduction of 4.8%, 20.2% and 42.8% using BAO + H0, BAO + CMB and BAO + CMB + H0 datasets, respectively. However due to the increased number of free parameters in the EoS information criteria favors ΛCDM over our DE model at this stage. Nevertheless it is crucial to obtain the dynamics of DE from the observational data to show the path for theoretical DE models based on fundamental physics.

  9. PROBING THE GALACTIC POTENTIAL WITH NEXT-GENERATION OBSERVATIONS OF DISK STARS

    International Nuclear Information System (INIS)

    Sumi, T.; Johnston, K. V.; Tremaine, S.; Spergel, D. N.; Majewski, S. R.

    2009-01-01

    Our current knowledge of the rotation curve of the Milky Way is remarkably poor compared to other galaxies, limited by the combined effects of extinction and the lack of large samples of stars with good distance estimates and proper motions. Near-future surveys promise a dramatic improvement in the number and precision of astrometric, photometric, and spectroscopic measurements of stars in the Milky Way's disk. We examine the impact of such surveys on our understanding of the Galaxy by 'observing' particle realizations of nonaxisymmetric disk distributions orbiting in an axisymmetric halo with appropriate errors and then attempting to recover the underlying potential using a Markov Chain Monte Carlo approach. We demonstrate that the azimuthally averaged gravitational force field in the Galactic plane-and hence, to a lesser extent, the Galactic mass distribution-can be tightly constrained over a large range of radii using a variety of types of surveys so long as the error distribution of the measurements of the parallax, proper motion, and radial velocity are well understood and the disk is surveyed globally. One advantage of our method is that the target stars can be selected nonrandomly in real or apparent-magnitude space to ensure just such a global sample without biasing the results. Assuming that we can always measure the line-of-sight velocity of a star with at least 1 km s -1 precision, we demonstrate that the force field can be determined to better than ∼1% for Galactocentric radii in the range R = 4-20 kpc using either: (1) small samples (a few hundred stars) with very accurate trigonometric parallaxes and good proper-motion measurements (uncertainties δ p,tri ∼ μ ∼ -1 respectively); (2) modest samples (∼1000 stars) with good indirect parallax estimates (e.g., uncertainty in photometric parallax δ p,phot ∼ 10%-20%) and good proper-motion measurements (δ μ ∼ 100 μas yr -1 ); or (3) large samples (∼10 4 stars) with good indirect parallax

  10. Van Allen Probes observation of a 360° phase shift in the flux modulation of injected electrons by ULF waves

    Science.gov (United States)

    Chen, X.-R.; Zong, Q.-G.; Zhou, X.-Z.; Blake, J. Bernard; Wygant, J. R.; Kletzing, C. A.

    2017-02-01

    We present Van Allen Probe observation of drift-resonance interaction between energetic electrons and ultralow frequency (ULF) waves on 29 October 2013. Oscillations in electron flux were observed at the period of ˜450 s, which is also the dominant period of the observed ULF magnetic pulsations. The phase shift of the electron fluxes (˜50 to 150 keV) across the estimated resonant energy (˜104 keV) is ˜360°. This phase relationship is different from the characteristic 180° phase shift as expected from the drift-resonance theory. We speculate that the additional 180° phase difference arises from the inversion of electron phase space density (PSD) gradient, which in turn is caused by the drift motion of the substorm injected electrons. This PSD gradient adjusts the characteristic particle signatures in the drift-resonance theory, which indicates a coupling effect between the magnetotail and the radiation belt and helps to better understand the wave-particle interaction in the magnetosphere.

  11. Kalman Filtering and Smoothing of the Van Allen Probes Observations to Estimate the Radial, Energy and Pitch Angle Diffusion Rates

    Science.gov (United States)

    Podladchikova, T.; Shprits, Y.; Kellerman, A. C.

    2015-12-01

    The Kalman filter technique combines the strengths of new physical models of the Earth's radiation belts with long-term spacecraft observations of electron fluxes and therefore provide an extremely useful method for the analysis of the state and evolution of the electron radiation belts. However, to get the reliable data assimilation output, the Kalman filter application is confronted with a set of fundamental problems. E.g., satellite measurements are usually limited to a single location in space, which confines the reconstruction of the global evolution of the radiation environment. The uncertainties arise from the imperfect description of the process dynamics and the presence of observation errors, which may cause the failure of data assimilation solution. The development of adaptive Kalman filter that combines the Van Allen Probes data and 3-D VERB code, its accurate customizations in the reconstruction of model describing the phase space density (PSD) evolution, extension of the possibilities to use measurement information, and the model adjustment by developing the identification techniques of model and measurement errors allowed us to reveal hidden and implicit regularities of the PSD dynamics and obtain quantitative and qualitative estimates of radial, energy and pitch angle diffusion characteristics from satellite observations. In this study we propose an approach to estimate radial, energy and pitch angle diffusion rates, as well as the direction of their propagation.

  12. Waveform modelling of 3-D seismic anisotropy in the Earth's mantle

    Science.gov (United States)

    Kendall, E.; Ferreira, A. M.; Chang, S. J.

    2017-12-01

    Considerable progress in seismic tomography in recent years has resulted in the agreement of large scale features in isotropic shear velocity models. Despite this, the mapping of more complex parameters such as radial anisotropy, is far from consistent across models owing to various factors such as the data sets, parametrisations, forward and inversion modelling schemes adopted by different research groups. Despite these challenges, this powerful probe provides crucial information to understand mantle flow in our dynamic planet. This study tests the robustness of upper mantle features in 3-D isotropic and radially anisotropic global mantle models such as S40RTS (Ritsema et al., 2011), S362WMANI+M (Moulik & Ekström, 2014), SAVANI (Auer et al., 2014) and SGLOBE-rani (Chang et al., 2015) and begins to interpret them in terms of geodynamical processes. We use the spectral element method (Komatitsch and Tromp, 1999) to compute full waveforms for over 300 paths for earthquakes with Mw between 6.4-7 and focal depths focus on fundamental mode surface waves in the period range T 25-100s. Our initial results show that SGLOBE-rani fits observed waveforms well and better than some other models. Moreover, we assess the adjustments in radial anisotropy needed to further improve the waveform fits in the Pacific. We find that overall SGLOBE- rani's anisotropic structure conforms well with the data, with errors in radial anisotropy in the order of ±10% for a large percentage of paths. In addition, preliminary results show greatly improved phase misfits when crustal thickness perturbations are taken into account in the modelling. Similar to previous studies, we observed that while the isotropic shear wave speed models portray a lithosphere-asthenosphere boundary deepening with age of the oceanic lithosphere, the relationship is less clear for radial anisotropy. Thus, we perform synthetic tests to investigate the depth resolution of radial anisotropy beneath the Pacific.

  13. The expected anisotropy in solid inflation

    Energy Technology Data Exchange (ETDEWEB)

    Bartolo, Nicola; Ricciardone, Angelo [Dipartimento di Fisica e Astronomia ' ' G. Galilei' ' , Università degli Studi di Padova, via Marzolo 8, I-35131, Padova (Italy); Peloso, Marco; Unal, Caner, E-mail: nicola.bartolo@pd.infn.it, E-mail: peloso@physics.umn.edu, E-mail: angelo.ricciardone@pd.infn.it, E-mail: unal@physics.umn.edu [School of Physics and Astronomy, University of Minnesota, 116 Church Street S.E., Minneapolis 55455 (United States)

    2014-11-01

    Solid inflation is an effective field theory of inflation in which isotropy and homogeneity are accomplished via a specific combination of anisotropic sources (three scalar fields that individually break isotropy). This results in specific observational signatures that are not found in standard models of inflation: a non-trivial angular dependence for the squeezed bispectrum, and a possibly long period of anisotropic inflation (to drive inflation, the ''solid'' must be very insensitive to any deformation, and thus background anisotropies are very slowly erased). In this paper we compute the expected level of statistical anisotropy in the power spectrum of the curvature perturbations of this model. To do so, we account for the classical background values of the three scalar fields that are generated on large (superhorizon) scales during inflation via a random walk sum, as the perturbation modes leave the horizon. Such an anisotropy is unavoidably generated, even starting from perfectly isotropic classical initial conditions. The expected level of anisotropy is related to the duration of inflation and to the amplitude of the squeezed bispectrum. If this amplitude is close to its current observational limit (so that one of the most interesting predictions of the model can be observed in the near future), we find that a level of statistical anisotropy F{sup 2} gives frozen and scale invariant vector perturbations on superhorizon scales.

  14. Phase structure of the Born-Infeld-anti-de Sitter black holes probed by non-local observables

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Xiao-Xiong [Chongqing Jiaotong University, School of Material Science and Engineering, Chongqing (China); Chinese Academy of Sciences, Institute of Theoretical Physics, Beijing (China); Liu, Xian-Ming [Center for Theoretical Physics, Massachusetts Institute of Technology, Cambridge, MA (United States); Hubei University for Nationalities, Center for Theoretical Physics, School of Sciences, Enshi, Hubei (China); Li, Li-Fang [Chinese Academy of Sciences, State Key Laboratory of Space Weather, Center for Space Science and Applied Research, Beijing (China)

    2016-11-15

    With the non-local observables such as two point correlation function and holographic entanglement entropy, we probe the phase structure of the Born-Infeld-anti-de Sitter black holes. For the case bQ > 0.5, where b is the Born-Infeld parameter and Q is the charge of the black hole, the phase structure is found to be similar to that of the Van der Waals phase transition, namely the black hole undergoes a first order phase transition and a second order phase transition before it reaches a stable phase. While for the case bQ < 0.5, a new phase branch emerges besides the Van der Waals phase transition. For the first order phase transition, the equal area law is checked, and for the second order phase transition, the critical exponent of the heat capacity is obtained. All these results are found to be the same as that observed in the entropy-temperature plane. (orig.)

  15. Combined convective and diffusive simulations: VERB-4D comparison with 17 March 2013 Van Allen Probes observations

    Science.gov (United States)

    Shprits, Yuri Y.; Kellerman, Adam C.; Drozdov, Alexander Y.; Spence, Harlan E.; Reeves, Geoffrey D.; Baker, Daniel N.

    2015-11-01

    This study is focused on understanding the coupling between different electron populations in the inner magnetosphere and the various physical processes that determine evolution of electron fluxes at different energies. Observations during the 17 March 2013 storm and simulations with a newly developed Versatile Electron Radiation Belt-4D (VERB-4D) are presented. Analysis of the drift trajectories of the energetic and relativistic electrons shows that electron trajectories at transitional energies with a first invariant on the scale of ~100 MeV/G may resemble ring current or relativistic electron trajectories depending on the level of geomagnetic activity. Simulations with the VERB-4D code including convection, radial diffusion, and energy diffusion are presented. Sensitivity simulations including various physical processes show how different acceleration mechanisms contribute to the energization of energetic electrons at transitional energies. In particular, the range of energies where inward transport is strongly influenced by both convection and radial diffusion are studied. The results of the 4-D simulations are compared to Van Allen Probes observations at a range of energies including source, seed, and core populations of the energetic and relativistic electrons in the inner magnetosphere.

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

    Science.gov (United States)

    Vittorio, Nicola; Silk, Joseph

    1992-01-01

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

  17. Electrical resistivity characterization of anisotropy in the Biscayne Aquifer.

    Science.gov (United States)

    Yeboah-Forson, Albert; Whitman, Dean

    2014-01-01

    Electrical anisotropy occurs when electric current flow varies with azimuth. In porous media, this may correspond to anisotropy in the hydraulic conductivity resulting from sedimentary fabric, fractures, or dissolution. In this study, a 28-electrode resistivity imaging system was used to investigate electrical anisotropy at 13 sites in the Biscayne Aquifer of SE Florida using the rotated square array method. The measured coefficient of electrical anisotropy generally ranged from 1.01 to 1.12 with values as high as 1.36 found at one site. The observed electrical anisotropy was used to estimate hydraulic anisotropy (ratio of maximum to minimum hydraulic conductivity) which ranged from 1.18 to 2.83. The largest values generally were located on the Atlantic Coastal Ridge while the lowest values were in low elevation areas on the margin of the Everglades to the west. The higher values of anisotropy found on the ridge may be due to increased dissolution rates of the oolitic facies of the Miami formation limestone compared with the bryozoan facies to the west. The predominate trend of minimum resistivity and maximum hydraulic conductivity was E-W/SE-NW beneath the ridge and E-W/SW-NE farther west. The anisotropy directions are similar to the predevelopment groundwater flow direction as indicated in published studies. This suggests that the observed anisotropy is related to the paleo-groundwater flow in the Biscayne Aquifer. © 2013, National Ground Water Association.

  18. Dark matter electron anisotropy. A universal upper limit

    International Nuclear Information System (INIS)

    Borriello, Enrico; Maccione, Luca; Cuoco, Alessandro

    2010-12-01

    Indirect searches of particle Dark Matter (DM) with high energy Cosmic Rays (CR) are affected by large uncertainties, coming both from the DM side, and from poor understanding of the astrophysical backgrounds. We show that, on the contrary, the DM intrinsic degree of anisotropy in the arrival directions of high energy CR electrons and positrons does not suffer from these unknowns. Furthermore, if contributions from possible local sources are neglected, the intrinsic DM anisotropy sets the maximum degree of total anisotropy. As a consequence, if some anisotropy larger than the DM upper bound is detected, its origin could not be ascribed to DM, and would constitute an unambiguous evidence for the presence of astrophysical local discrete sources of high energy electrons and positrons. The Fermi-LAT will be able to probe such scenarios in the next years. (orig.)

  19. On the Effect of Geomagnetic Storms on Relativistic Electrons in the Outer Radiation Belt: Van Allen Probes Observations

    Science.gov (United States)

    Moya, Pablo S.; Pinto, Víctor A.; Sibeck, David G.; Kanekal, Shrikanth G.; Baker, Daniel N.

    2017-11-01

    Using Van Allen Probes Energetic Particle, Composition, and Thermal Plasma-Relativistic Electron-Proton Telescope (ECT-REPT) observations, we performed a statistical study on the effect of geomagnetic storms on relativistic electrons fluxes in the outer radiation belt for 78 storms between September 2012 and June 2016. We found that the probability of enhancement, depletion, and no change in flux values depends strongly on L and energy. Enhancement events are more common for ˜2 MeV electrons at L ˜ 5, and the number of enhancement events decreases with increasing energy at any given L shell. However, considering the percentage of occurrence of each kind of event, enhancements are more probable at higher energies, and the probability of enhancement tends to increases with increasing L shell. Depletion are more probable for 4-5 MeV electrons at the heart of the outer radiation belt, and no-change events are more frequent at L 4.5 the probability of enhancement, depletion, or no-change response presents little variation for all energies. Because these probabilities remain relatively constant as a function of radial distance in the outer radiation belt, measurements obtained at geosynchronous orbit may be used as a proxy to monitor E≥1.8 MeV electrons in the outer belt.

  20. Flow of Energy through the Inner Magnetosphere during the March 17, 2015 solar storm as observed by the Van Allen Probes Radiation Belt Storm Probes Ion Composition Experiment (RBSPICE)

    Science.gov (United States)

    Manweiler, J. W.; Madanian, H.; Gerrard, A. J.; Patterson, J. D.; Mitchell, D. G.; Lanzerotti, L. J.

    2017-12-01

    On March 17, 2015, a large solar storm impacted the Earth's magnetosphere with a maximum negative Dst of -232 nT. We report on the temporal and spatial evolution of the proton energetic particle distributions in phase space during this storm, as measured by the Radiation Belt Storm Probes Ion Composition Experiment (RBSPICE) instrument on board each of the Van Allen Probes. We characterize the distribution prior to onset of the storm to provide a definition of quiet time conditions. We then show how the distribution evolves during the storm noting key changes of the distribution as a function of L and MLT and showing how the pitch angle distributions change throughout the storm. These observations displayed a number of interesting features of the storm including high beta plasma conditions and multiple injections of protons into the inner magnetosphere. We present the radial changes of the distribution at storm onset and following the evolution of the distribution during storm recovery. We compare observations of the East/West asymmetry in the proton distribution before versus after onset using both Van Allen Probes A and B spacecraft observations. Finally, we note interesting changes in the distribution showing an anomalous dropout in mid-energies of the distribution and observe an outward radial propagation of this dropout during recovery.

  1. Large Friction Anisotropy of a Polydiacetylene Monolayer

    International Nuclear Information System (INIS)

    Burns, A.R.; Carpick, R.W.; Sasaki, D.Y.

    1999-01-01

    Friction force microscopy measurements of a polydiacetylene monolayer film reveal a 300% friction anisotropy that is correlated with the film structure. The film consists of a monolayer of the red form of N-(2-ethanol)- 10,12 pentacosadiynamide, prepared on a Langmuir trough and deposited on a mica substrate. As confirmed by atomic force microscopy and fluorescence microscopy, the monolayer consists of domains of linearly oriented conjugated backbones with pendant hydrocarbon side chains above and below the backbones. Maximum friction occurs when the sliding direction is perpendicular to the backbone. We propose that the backbones impose anisotropic packing of the hydrocarbon side chains which leads to the observed friction anisotropy. Friction anisotropy is therefore a sensitive, optically-independent indicator of polymer backbone direction and monolayer structural properties

  2. Measuring anisotropies in the cosmic neutrino background

    Science.gov (United States)

    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. Bias in the Cq value observed with hydrolysis probe based quantitative PCR can be corrected with the estimated PCR efficiency value

    NARCIS (Netherlands)

    Tuomi, Jari Michael; Voorbraak, Frans; Jones, Douglas L.; Ruijter, Jan M.

    2010-01-01

    For real-time monitoring of PCR amplification of DNA, quantitative PCR (qPCR) assays use various fluorescent reporters. DNA binding molecules and hybridization reporters (primers and probes) only fluoresce when bound to DNA and result in the non-cumulative increase in observed fluorescence.

  4. Probing the Aggregation Behavior of Neat Imidazolium-Based Alkyl Sulfate (Alkyl = Ethyl, Butyl, Hexyl, and Octyl) Ionic Liquids through Time Resolved Florescence Anisotropy and NMR and Fluorescence Correlation Spectroscopy Study.

    Science.gov (United States)

    Majhi, Debashis; Pabbathi, Ashok; Sarkar, Moloy

    2016-01-14

    Aggregation behavior of a series of neat 1-ethyl 3-methylimidazolium alkyl sulfate (alkyl = ethyl, butyl, hexyl, and octyl) ionic liquids has been investigated through combined time-resolved fluorescence spectroscopy, 1-D and 2-D NMR spectroscopy, and fluorescence correlation spectroscopy (FCS). Interestingly, experimentally measured rotational relaxation times (τr) for ethyl, butyl, hexyl and octyl systems are measured to be 2.25, 1.64, 1.36, and 1.32 times higher than the estimated (from Stokes-Einstein-Debye theory) values for the same respective systems. This indicates that the emitting species is not the monomeric imidazolium moiety rather an associated species, and volume of the rotating fluorescing species decreases even though the length of the alkyl moiety on the anions is increased. The shift in the (1)H proton signal as well as a change in the width of the same signal upon dilution of the neat ionic liquids indicates that ionic liquids exist in the aggregated form. Further investigation through the 2D-ROESY experiment shows that interaction between imidazolium and sulfate is relatively stronger in the ethyl system than that of the longer octyl system. FCS measurements independently show that the hydrodynamic volume decreases with an increase in the anion chain length. The NMR and FCS results are consistent with the findings of the fluorescence anisotropy study.

  5. Efficiency of radial transport of ices in protoplanetary disks probed with infrared observations: the case of CO2

    Science.gov (United States)

    Bosman, Arthur D.; Tielens, Alexander G. G. M.; van Dishoeck, Ewine F.

    2018-04-01

    Context. Radial transport of icy solid material from the cold outer disk to the warm inner disk is thought to be important for planet formation. However, the efficiency at which this happens is currently unconstrained. Efficient radial transport of icy dust grains could significantly alter the composition of the gas in the inner disk, enhancing the gas-phase abundances of the major ice constituents such as H2O and CO2. Aim. Our aim is to model the gaseous CO2 abundance in the inner disk and use this to probe the efficiency of icy dust transport in a viscous disk. From the model predictions, infrared CO2 spectra are simulated and features that could be tracers of icy CO2, and thus dust, radial transport efficiency are investigated. Methods: We have developed a 1D viscous disk model that includes gas accretion and gas diffusion as well as a description for grain growth and grain transport. Sublimation and freeze-out of CO2 and H2O has been included as well as a parametrisation of the CO2 chemistry. The thermo-chemical code DALI was used to model the mid-infrared spectrum of CO2, as can be observed with JWST-MIRI. Results: CO2 ice sublimating at the iceline increases the gaseous CO2 abundance to levels equal to the CO2 ice abundance of 10-5, which is three orders of magnitude more than the gaseous CO2 abundances of 10-8 observed by Spitzer. Grain growth and radial drift increase the rate at which CO2 is transported over the iceline and thus the gaseous CO2 abundance, further exacerbating the problem. In the case without radial drift, a CO2 destruction rate of at least 10-11 s-1 or a destruction timescale of at most 1000 yr is needed to reconcile model prediction with observations. This rate is at least two orders of magnitude higher than the fastest destruction rate included in chemical databases. A range of potential physical mechanisms to explain the low observed CO2 abundances are discussed. Conclusions: We conclude that transport processes in disks can have

  6. Earth Inner Core Anisotropy using PKiKP and PKIIKP Reflection Pairs

    Science.gov (United States)

    Chew, J.; Hu, H.; Zheng, Y.

    2017-12-01

    The idea of an anisotropic inner core with a fast polar axis is widely supported with past studies. Research also suggests that this anisotropy varies with depth and between the eastern and western hemispheres. Most inner core research is accomplished through the observation of differential traveltimes between two transmitted waves sampling shallow parts of the inner core. It is possible that the large epicentral distance can create a significant ray path separation in the mantle, which could introduce error in calculations due to mantle heterogeneities. We introduce a new method to study the effects of solely the inner core using reflected PKiKP and PKIIKP waves at small epicentral distances (up to about 40 degrees). This observation geometry yields a clean time window in which these phases can be identified. The small distance is key to minimizing effects of small mantle heterogeneities, providing a robust anisotropy picture for probing the whole inner core rather than just the top part of the inner core. Data for this project includes seismograms obtained from the IRIS for global earthquakes from 1990 to 2016 of moment magnitudes 6.1-6.5. Seismic data is loaded into a Matlab GUI program from which the PKiKP-PKIIKP phase pairs can be picked at the same station. Theoretical phase traveltimes calculated from the iasp91 model are plotted in the GUI program to aid in choosing the proper phases. After compiling an initial set of 873 traveltime pairs from the given raw data, no clear form of anisotropy can be seen for the whole inner core; this is in sharp contrast to the commonly observed polar dependence for the shallow part of the inner core. A stacking of nearby receivers in an array is used to increase the SNR of traces per earthquake. From these cleaner seismograms, we will show more accurate picks to properly quantify Earth inner core anisotropy.

  7. Inflating, Warming Up and Probing the Pre-Bangian Universe

    CERN Document Server

    AUTHOR|(CDS)2083955

    1999-01-01

    Classical and quantum gravitational instabilities, can, respectively, inflate and warm up a primordial Universe satisfying a superstring-motivated principle of "Asymptotic Past Triviality". A physically viable big bang is thus generated without invoking either large fine-tunings or a long period of post-big bang inflation. Properties of the pre-bangian Universe can be probed through its observable relics, which include: i) a (possibly observable) stochastic gravitational-wave background; ii) a (possible) new mechanism for seeding the galactic magnetic fields; iii) a (possible) new source of large-scale structure and CMB anisotropy.

  8. Anisotropy modulated stepwise magnetization in triangular Heisenberg antiferromagnet

    International Nuclear Information System (INIS)

    Yao Xiaoyan; Liu Junming; Lo, Veng Cheong

    2011-01-01

    During the course of tuning anisotropy from Ising type to zero, the variation of magnetization (M) steps against magnetic field (h) is investigated in a triangular antiferromagnetic Heisenberg model using Monte Carlo techniques. It is revealed that the anisotropy is an essential key to induce the temperature-dependent stepwise M(h) curve observed in frustrated magnetic system, and it can be employed to modulate this steplike magnetic behavior effectively. When the anisotropy is strengthened, a ground state transition occurs from the homogeneous 120 o triangular structure to the collinear partially disordered antiferromagnetic state. No M step is detected in the system without anisotropy. But if the anisotropy is nonzero, the M 0 /3 step (where M 0 is the saturated M) will emerge on M(h) curve, which is due to an h-induced quasi-collinear ferrimagnetic state. This M 0 /3 step can be extended by increasing the anisotropy. When the M 0 /3 plateau dominates the h-range broad enough, the equidistant metastable substeps, which originates from the disorders frozen in the frustrated collinear spin structure, appear to be superposed on the M 0 /3 plateau. Thus the system with a strong anisotropy presents the whole temperature evolution of stepwise M(h) curve in quantitative agreement with the experiments of Ca 3 Co 2 O 6 . - Highlights: → Variation of M steps is investigated by tuning anisotropy from Ising type to zero. → Anisotropy is essential to induce T-dependent multistep M against magnetic field. → Simulation with strong anisotropy reproduces T-evolution of M steps in Ca 3 Co 2 O 6 . → Metastable substeps at low T can be enhanced by increasing anisotropy.

  9. Insights into asthenospheric anisotropy and deformation in Mainland China

    Science.gov (United States)

    Zhu, Tao

    2018-03-01

    Seismic anisotropy can provide direct constraints on asthenospheric deformation which also can be induced by the inherent mantle flow within our planet. Mantle flow calculations thus have been an effective tool to probe asthenospheric anisotropy. To explore the source of seismic anisotropy, asthenospheric deformation and the effects of mantle flow on seismic anisotropy in Mainland China, mantle flow models driven by plate motion (plate-driven) and by a combination of plate motion and mantle density heterogeneity (plate-density-driven) are used to predict the fast polarization direction of shear wave splitting. Our results indicate that: (1) plate-driven or plate-density-driven mantle flow significantly affects the predicted fast polarization direction when compared with simple asthenospheric flow commonly used in interpreting the asthenospheric source of seismic anisotropy, and thus new insights are presented; (2) plate-driven flow controls the fast polarization direction while thermal mantle flow affects asthenospheric deformation rate and local deformation direction significantly; (3) asthenospheric flow is an assignable contributor to seismic anisotropy, and the asthenosphere is undergoing low, large or moderate shear deformation controlled by the strain model, the flow plane/flow direction model or both in most regions of central and eastern China; and (4) the asthenosphere is under more rapid extension deformation in eastern China than in western China.

  10. Magnetic transitions and phases in random-anisotropy magnets

    International Nuclear Information System (INIS)

    Sellmyer, D.J.; Nafis, S.; O'Shea, M.J.

    1988-01-01

    The generality and universality of the Ising spin-glass-like phase transitions observed in several rare-earth, random-anisotropy magnets are discussed. Some uncertainties and practical problems in determining critical exponents are considered, and a comparison is made to insulating spin glasses and crystalline spin glasses where an apparent anisotropy-induced crossover from Heisenberg to Ising-like behavior is seen. The observation of a reentrant transition in a weak anisotropy system and its correlation with the theory of Chudnovsky, Saslow, and Serota [Phys. Rev. B 33, 251 (1986)] for the correlated spin glass is discussed

  11. Magnetic transitions and phases in random-anisotropy magnets

    Science.gov (United States)

    Sellmyer, D. J.; Nafis, S.; O'Shea, M. J.

    1988-04-01

    The generality and universality of the Ising spin-glass-like phase transitions observed in several rare-earth, random-anisotropy magnets are discussed. Some uncertainties and practical problems in determining critical exponents are considered, and a comparison is made to insulating spin glasses and crystalline spin glasses where an apparent anisotropy-induced crossover from Heisenberg to Ising-like behavior is seen. The observation of a reentrant transition in a weak anisotropy system and its correlation with the theory of Chudnovsky, Saslow, and Serota [Phys. Rev. B 33, 251 (1986)] for the correlated spin glass is discussed.

  12. Ultrafast Dynamics of the VO2 Insulator-to-Metal Transition Observed by Nondegenerate Pump-Probe Spectroscopy

    Directory of Open Access Journals (Sweden)

    Haglund R. F.

    2013-03-01

    Full Text Available Non-degenerate pump (1.5 eV-probe (0.4 eV transmission spectroscopy on vanadium dioxide films grown on glass and three different sapphire substrates shows systematic variations with substrate that correlate with VO2 grain size and laser fluence. Temperature dependent measurements showed changes in the electronic response that is proportional to the metallic fraction.

  13. Identification of the source of quasiperiodic VLF emissions using ground-based and Van Allen Probes satellite observations

    Czech Academy of Sciences Publication Activity Database

    Titova, E. E.; Kozelov, B. V.; Demekhov, A. G.; Manninen, J.; Santolík, Ondřej; Kletzing, C. A.; Reeves, G.

    2015-01-01

    Roč. 42, č. 15 (2015), s. 6137-6145 ISSN 0094-8276 R&D Projects: GA ČR(CZ) GAP209/11/2280 Institutional support: RVO:68378289 Keywords : energetic electrons * quasiperiodic emissions * Van Allen Probes * VLF waves Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 4.212, year: 2015 http://onlinelibrary.wiley.com/doi/10.1002/2015GL064911/full

  14. Van Allen Probes, THEMIS, GOES, and Cluster observations of EMIC waves, ULF pulsations, and an electron flux dropout

    Czech Academy of Sciences Publication Activity Database

    Sigsbee, K.; Kletzing, C. A.; Smith, C. W.; MacDowall, R.; Spence, H.; Reeves, G.; Blake, J. B.; Baker, D. N.; Green, J. C.; Singer, H. J.; Carr, C.; Santolík, Ondřej

    2016-01-01

    Roč. 121, č. 3 (2016), s. 1990-2008 ISSN 2169-9380 Grant - others:AV ČR(CZ) AP1401 Program:Akademická prémie - Praemium Academiae Institutional support: RVO:68378289 Keywords : EMIC waves * ULF pulsations * electron flux dropouts * Dst effect * magnetopause shadowing * Van Allen Probes Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.733, year: 2016 http://onlinelibrary.wiley.com/doi/10.1002/2014JA020877/full

  15. Daytime Thermal Anisotropy of Urban Neighbourhoods: Morphological Causation

    Directory of Open Access Journals (Sweden)

    E. Scott Krayenhoff

    2016-01-01

    Full Text Available Surface temperature is a key variable in boundary-layer meteorology and is typically acquired by remote observation of emitted thermal radiation. However, the three-dimensional structure of cities complicates matters: uneven solar heating of urban facets produces an “effective anisotropy” of surface thermal emission at the neighbourhood scale. Remotely-sensed urban surface temperature varies with sensor view angle as a consequence. The authors combine a microscale urban surface temperature model with a thermal remote sensing model to predict the effective anisotropy of simplified neighbourhood configurations. The former model provides detailed surface temperature distributions for a range of “urban” forms, and the remote sensing model computes aggregate temperatures for multiple view angles. The combined model’s ability to reproduce observed anisotropy is evaluated against measurements from a neighbourhood in Vancouver, Canada. As in previous modeling studies, anisotropy is underestimated. Addition of moderate coverages of small (sub-facet scale structure can account for much of the missing anisotropy. Subsequently, over 1900 sensitivity simulations are performed with the model combination, and the dependence of daytime effective thermal anisotropy on diurnal solar path (i.e., latitude and time of day and blunt neighbourhood form is assessed. The range of effective anisotropy, as well as the maximum difference from nadir-observed brightness temperature, peak for moderate building-height-to-spacing ratios (H/W, and scale with canyon (between-building area; dispersed high-rise urban forms generate maximum anisotropy. Maximum anisotropy increases with solar elevation and scales with shortwave irradiance. Moreover, it depends linearly on H/W for H/W < 1.25, with a slope that depends on maximum off-nadir sensor angle. Decreasing minimum brightness temperature is primarily responsible for this linear growth of maximum anisotropy. These

  16. In situ seismic anisotropy around deep earthquakes in Japan subduction slabs using Japan Meteorological Agency moment tensors

    Science.gov (United States)

    Li, J.; Zheng, Y.; Thomsen, L.

    2017-12-01

    Knowing the in situ seismic anisotropy around deep earthquakes in slabs is important in understanding deep-earthquake mechanism as it may provide critically needed information about the rock fabric where deep earthquakes occur. It has been recognized for about 50 years that many deep earthquakes are not double-couple (DC) events. Previously we showed that in situ anisotropy around deep earthquakes could explain such observed non-DC events. Traditionally, the shear wave splitting method has been used to infer such anisotropy around deep earthquakes but this is challenging because it will need many crossing ray paths for the method to localize the anisotropic region (Long 2013). In this abstract, we adopt the same procedure to obtain anisotropy in the Pacific slab under Japan using moment tensors provided by the Japan Meteorological Agency using the F-net data. We directly probe the in situ anisotropy within the subducting slabs using the radiation patterns (represented by the moment tensors) of deep earthquakes (with depth greater than 60 km). By assuming a group of shear dislocation events embedded in a common tilted transversely isotropic (TTI) medium, we used the moment tensors as our input data to invert for the anisotropy in Mariana-Japan-Kuril subducting zone. The TTI medium is characterized by the P and S wave velocities along the symmetry axis (described by two free angles) and three Thomsen parameters. We divided the deep earthquake events into 9 groups by their spatial proximity using the k-means clustering method (Hartigan and Wong 1979). These 9 groups include 2 intermediate-depth groups (depth from 60 km to 300 km) and 7 deep-focus groups (depth greater than 300 km). Our inversion results show that the inverted TTI symmetry axes are perpendicular to the slab interface for two intermediate-depth groups (consistent with dehydration metamorphic reactions) and parallel to the slab interface for 7 deep-focus group. The shear wave anisotropy is best resolved

  17. Detecting 3D Vegetation Structure with the Galileo Space Probe: Can a Distant Probe Detect Vegetation Structure on Earth?

    Directory of Open Access Journals (Sweden)

    Christopher E Doughty

    Full Text Available Sagan et al. (1993 used the Galileo space probe data and first principles to find evidence of life on Earth. Here we ask whether Sagan et al. (1993 could also have detected whether life on Earth had three-dimensional structure, based on the Galileo space probe data. We reanalyse the data from this probe to see if structured vegetation could have been detected in regions with abundant photosynthetic pigments through the anisotropy of reflected shortwave radiation. We compare changing brightness of the Amazon forest (a region where Sagan et al. (1993 noted a red edge in the reflectance spectrum, indicative of photosynthesis as the planet rotates to a common model of reflectance anisotropy and found measured increase of surface reflectance of 0.019 ± 0.003 versus a 0.007 predicted from only anisotropic effects. We hypothesize the difference was due to minor cloud contamination. However, the Galileo dataset had only a small change in phase angle (sun-satellite position which reduced the observed anisotropy signal and we demonstrate that theoretically if the probe had a variable phase angle between 0-20°, there would have been a much larger predicted change in surface reflectance of 0.1 and under such a scenario three-dimensional vegetation structure on Earth could possibly have been detected. These results suggest that anisotropic effects may be useful to help determine whether exoplanets have three-dimensional vegetation structure in the future, but that further comparisons between empirical and theoretical results are first necessary.

  18. Detecting 3D Vegetation Structure with the Galileo Space Probe: Can a Distant Probe Detect Vegetation Structure on Earth?

    Science.gov (United States)

    Doughty, Christopher E; Wolf, Adam

    2016-01-01

    Sagan et al. (1993) used the Galileo space probe data and first principles to find evidence of life on Earth. Here we ask whether Sagan et al. (1993) could also have detected whether life on Earth had three-dimensional structure, based on the Galileo space probe data. We reanalyse the data from this probe to see if structured vegetation could have been detected in regions with abundant photosynthetic pigments through the anisotropy of reflected shortwave radiation. We compare changing brightness of the Amazon forest (a region where Sagan et al. (1993) noted a red edge in the reflectance spectrum, indicative of photosynthesis) as the planet rotates to a common model of reflectance anisotropy and found measured increase of surface reflectance of 0.019 ± 0.003 versus a 0.007 predicted from only anisotropic effects. We hypothesize the difference was due to minor cloud contamination. However, the Galileo dataset had only a small change in phase angle (sun-satellite position) which reduced the observed anisotropy signal and we demonstrate that theoretically if the probe had a variable phase angle between 0-20°, there would have been a much larger predicted change in surface reflectance of 0.1 and under such a scenario three-dimensional vegetation structure on Earth could possibly have been detected. These results suggest that anisotropic effects may be useful to help determine whether exoplanets have three-dimensional vegetation structure in the future, but that further comparisons between empirical and theoretical results are first necessary.

  19. Mobile Probing and Probes

    DEFF Research Database (Denmark)

    Duvaa, Uffe; Ørngreen, Rikke; Weinkouff, Anne-Gitte

    2012-01-01

    Mobile probing is a method, which has been developed for learning about digital work situations, as an approach to discover new grounds. The method can be used when there is a need to know more about users and their work with certain tasks, but where users at the same time are distributed (in time...... and space). Mobile probing was inspired by the cultural probe method, and was influenced by qualitative interview and inquiry approaches. The method has been used in two subsequent projects, involving school children (young adults at 15-17 years old) and employees (adults) in a consultancy company. Findings...... point to mobile probing being a flexible method for uncovering the unknowns, as a way of getting rich data to the analysis and design phases. On the other hand it is difficult to engage users to give in depth explanations, which seem easier in synchronous dialogs (whether online or face2face...

  20. Mobile Probing and Probes

    DEFF Research Database (Denmark)

    Duvaa, Uffe; Ørngreen, Rikke; Weinkouff Mathiasen, Anne-Gitte

    2013-01-01

    Mobile probing is a method, developed for learning about digital work situations, as an approach to discover new grounds. The method can be used when there is a need to know more about users and their work with certain tasks, but where users at the same time are distributed (in time and space......). Mobile probing was inspired by the cultural probe method, and was influenced by qualitative interview and inquiry approaches. The method has been used in two subsequent projects, involving school children (young adults at 15-17 years old) and employees (adults) in a consultancy company. Findings point...... to mobile probing being a flexible method for uncovering the unknowns, as a way of getting rich data to the analysis and design phases. On the other hand it is difficult to engage users to give in depth explanations, which seem easier in synchronous dialogs (whether online or face2face). The development...

  1. Magnetic anisotropy of ultrafine 316L stainless steel fibers

    Energy Technology Data Exchange (ETDEWEB)

    Shyr, Tien-Wei, E-mail: twshyr@fcu.edu.tw [Department of Fiber and Composite Materials, Feng Chia University, No. 100, Wenhwa Road, Seatwen, Taichung 40724, Taiwan, ROC (China); Huang, Shih-Ju [Department of Fiber and Composite Materials, Feng Chia University, No. 100, Wenhwa Road, Seatwen, Taichung 40724, Taiwan, ROC (China); Wur, Ching-Shuei [Department of Physics, National Cheng Kung University, No. 1, University Road, Tainan 70101, Taiwan, ROC (China)

    2016-12-01

    An as-received 316L stainless steel fiber with a diameter of 20 μm was drawn using a bundle drawing process at room temperature to form ultrafine stainless steel fibers with diameters of 12, 8, and 6 μm. The crystalline phases of the fibers were analyzed using the X-ray diffraction (XRD) profile fitting technique. The grain sizes of γ-austenite and α′-martensite were reduced to nanoscale sizes after the drawing process. XRD analysis and focused ion beam-scanning electron microscope observations showed that the newly formed α′-martensitic grains were closely arrayed in the drawing direction. The magnetic property was measured using a superconducting quantum interference device vibrating sample magnetometer. The magnetic anisotropy of the fibers was observed by applying a magnetic field parallel and perpendicular to the fiber axis. The results showed that the microstructure anisotropy including the shape anisotropy, magnetocrystalline anisotropy, and the orientation of the crystalline phases strongly contributed to the magnetic anisotropy. - Highlights: • The martensitic transformation of the 316L SS fiber occurred during the cold drawn. • The grain sizes of γ-austenite and α′-martensite were reduced to the nanoscale. • The newly formed martensitic grains were closely arrayed in the drawing direction. • The drawing process caused the magnetic easy axis to be aligned with the fiber axis. • The microstructure anisotropy strongly contributed to the magnetic anisotropy.

  2. Microwave background anisotropies in quasiopen inflation

    Science.gov (United States)

    García-Bellido, Juan; Garriga, Jaume; Montes, Xavier

    1999-10-01

    Quasiopenness seems to be generic to multifield models of single-bubble open inflation. Instead of producing infinite open universes, these models actually produce an ensemble of very large but finite inflating islands. In this paper we study the possible constraints from CMB anisotropies on existing models of open inflation. The effect of supercurvature anisotropies combined with the quasiopenness of the inflating regions make some models incompatible with observations, and severely reduces the parameter space of others. Supernatural open inflation and the uncoupled two-field model seem to be ruled out due to these constraints for values of Ω0<~0.98. Others, such as the open hybrid inflation model with suitable parameters for the slow roll potential can be made compatible with observations.

  3. Measurement of the dark matter velocity anisotropy profile in galaxy clusters

    International Nuclear Information System (INIS)

    Host, Ole

    2009-01-01

    Dark matter halos contribute the major part of the mass of galaxy clusters and the formation of these cosmological structures have been investigated in numerical simulations. Observations have been found to be in good agreement with the numerical predictions regarding the spatial distribution of dark matter, i.e. the mass profile. However, the dynamics of dark matter in halos has so far proved a greater challenge to probe observationally. We have used observations of 16 relaxed galaxy clusters to show that the dark matter velocity dispersion is larger along the radial direction than along the tangential, and that the magnitude of this velocity anisotropy β varies with radius. This measurement implies that the collective behaviour of dark matter particles is fundamentally different from that of baryonic particles and constrains the self-interaction per unit mass. The radial variation of the anisotropy velocity agrees with the predictions so that, on cluster scales, there is now excellent agreement between numerical predictions and observations regarding the phase space of dark matter.

  4. Observation of chorus waves by the Van Allen Probes: dependence on solar wind parameters and scale size

    Science.gov (United States)

    Aryan, H.; Sibeck, D. G.; Balikhin, M. A.; Agapitov, O. V.; Kletzing, C.

    2016-12-01

    Highly energetic electrons in the Earth's Van Allen radiation belts can cause serious damage to spacecraft electronic systems, and affect the atmospheric composition if they precipitate into the upper atmosphere. Whistler mode chorus waves have attracted significant attention in recent decades for their crucial role in the acceleration and loss of energetic electrons that ultimately change the dynamics of the radiation belts. The distribution of these waves in the inner magnetosphere is commonly presented as a function of geomagnetic activity. However, geomagnetic indices are non-specific parameters that are compiled from imperfectly covered ground based measurements. The present study uses wave data from the two Van Allen Probes to present the distribution of lower band chorus waves not only as functions of single geomagnetic index and solar wind parameters, but also as functions of combined parameters. Also the current study takes advantage of the unique equatorial orbit of the Van Allen Probes to estimate the average scale size of chorus wave packets, during close separations between the two spacecraft, as a function of radial distance, magnetic latitude, and geomagnetic activity respectively. Results show that the average scale size of chorus wave packets is approximately 1300 - 2300 km. The results also show that the inclusion of combined parameters can provide better representation of the chorus wave distributions in the inner magnetosphere, and therefore can further improve our knowledge of the acceleration and loss of radiation belt electrons.

  5. Observation of Chorus Waves by the Van Allen Probes: Dependence on Solar Wind Parameters and Scale Size

    Science.gov (United States)

    Aryan, Homayon; Sibeck, David; Balikhin, Michael; Agapitov, Oleksiy; Kletzing, Craig

    2016-01-01

    Highly energetic electrons in the Earths Van Allen radiation belts can cause serious damage to spacecraft electronic systems and affect the atmospheric composition if they precipitate into the upper atmosphere. Whistler mode chorus waves have attracted significant attention in recent decades for their crucial role in the acceleration and loss of energetic electrons that ultimately change the dynamics of the radiation belts. The distribution of these waves in the inner magnetosphere is commonly presented as a function of geomagnetic activity. However, geomagnetic indices are nonspecific parameters that are compiled from imperfectly covered ground based measurements. The present study uses wave data from the two Van Allen Probes to present the distribution of lower band chorus waves not only as functions of single geomagnetic index and solar wind parameters but also as functions of combined parameters. Also the current study takes advantage of the unique equatorial orbit of the Van Allen Probes to estimate the average scale size of chorus wave packets, during close separations between the two spacecraft, as a function of radial distance, magnetic latitude, and geomagnetic activity, respectively. Results show that the average scale size of chorus wave packets is approximately 13002300 km. The results also show that the inclusion of combined parameters can provide better representation of the chorus wave distributions in the inner magnetosphere and therefore can further improve our knowledge of the acceleration and loss of radiation belt electrons.

  6. Prompt injections of highly relativistic electrons induced by interplanetary shocks: A statistical study of Van Allen Probes observations

    Science.gov (United States)

    Schiller, Q.; Kanekal, S. G.; Jian, L. K.; Li, X.; Jones, A.; Baker, D. N.; Jaynes, A.; Spence, H. E.

    2016-12-01

    We conduct a statistical study on the sudden response of outer radiation belt electrons due to interplanetary (IP) shocks during the Van Allen Probes era, i.e., 2012 to 2015. Data from the Relativistic Electron-Proton Telescope instrument on board Van Allen Probes are used to investigate the highly relativistic electron response (E > 1.8 MeV) within the first few minutes after shock impact. We investigate the relationship of IP shock parameters, such as Mach number, with the highly relativistic electron response, including spectral properties and radial location of the shock-induced injection. We find that the driving solar wind structure of the shock does not affect occurrence for enhancement events, 25% of IP shocks are associated with prompt energization, and 14% are associated with MeV electron depletion. Parameters that represent IP shock strength are found to correlate best with highest levels of energization, suggesting that shock strength may play a key role in the severity of the enhancements. However, not every shock results in an enhancement, indicating that magnetospheric preconditioning may be required.

  7. Quantifying seismic anisotropy induced by small-scale chemical heterogeneities

    Science.gov (United States)

    Alder, C.; Bodin, T.; Ricard, Y.; Capdeville, Y.; Debayle, E.; Montagner, J. P.

    2017-12-01

    Observations of seismic anisotropy are usually used as a proxy for lattice-preferred orientation (LPO) of anisotropic minerals in the Earth's mantle. In this way, seismic anisotropy observed in tomographic models provides important constraints on the geometry of mantle deformation associated with thermal convection and plate tectonics. However, in addition to LPO, small-scale heterogeneities that cannot be resolved by long-period seismic waves may also produce anisotropy. The observed (i.e. apparent) anisotropy is then a combination of an intrinsic and an extrinsic component. Assuming the Earth's mantle exhibits petrological inhomogeneities at all scales, tomographic models built from long-period seismic waves may thus display extrinsic anisotropy. In this paper, we investigate the relation between the amplitude of seismic heterogeneities and the level of induced S-wave radial anisotropy as seen by long-period seismic waves. We generate some simple 1-D and 2-D isotropic models that exhibit a power spectrum of heterogeneities as what is expected for the Earth's mantle, that is, varying as 1/k, with k the wavenumber of these heterogeneities. The 1-D toy models correspond to simple layered media. In the 2-D case, our models depict marble-cake patterns in which an anomaly in shear wave velocity has been advected within convective cells. The long-wavelength equivalents of these models are computed using upscaling relations that link properties of a rapidly varying elastic medium to properties of the effective, that is, apparent, medium as seen by long-period waves. The resulting homogenized media exhibit extrinsic anisotropy and represent what would be observed in tomography. In the 1-D case, we analytically show that the level of anisotropy increases with the square of the amplitude of heterogeneities. This relation is numerically verified for both 1-D and 2-D media. In addition, we predict that 10 per cent of chemical heterogeneities in 2-D marble-cake models can

  8. Omega from the anisotropy of the redshift correlation function

    Science.gov (United States)

    Hamilton, A. J. S.

    1993-01-01

    Peculiar velocities distort the correlation function of galaxies observed in redshift space. In the large scale, linear regime, the distortion takes a characteristic quadrupole plus hexadecapole form, with the amplitude of the distortion depending on the cosmological density parameter omega. Preliminary measurements are reported here of the harmonics of the correlation function in the CfA, SSRS, and IRAS 2 Jansky redshift surveys. The observed behavior of the harmonics agrees qualitatively with the predictions of linear theory on large scales in every survey. However, real anisotropy in the galaxy distribution induces large fluctuations in samples which do not yet probe a sufficiently fair volume of the Universe. In the CfA 14.5 sample in particular, the Great Wall induces a large negative quadrupole, which taken at face value implies an unrealistically large omega 20. The IRAS 2 Jy survey, which covers a substantially larger volume than the optical surveys and is less affected by fingers-of-god, yields a more reliable and believable value, omega = 0.5 sup +.5 sub -.25.

  9. Radial Diffusion Caused by Pitch Angle Scattering and Drift Shell Splitting - Simulation and Van Allen Probes Observations

    Science.gov (United States)

    Henderson, M. G.; Morley, S.; Cunningham, G.; Tu, W.; Reeves, G. D.; Fennell, J. F.; Claudepierre, S. G.; Blake, J. B.; Spence, H.; Baker, D. N.

    2013-12-01

    In realistic asymmetric magnetic fields, particles with different pitch angles starting on the same field line will trace out different drift shells. As a result of this drift shell splitting, pitch angle scattering automatically leads to additional radial diffusion. At a given position on a drift shell, the instantaneous DLL associated with this process is related to the gradient of L* with respect to equatorial pitch angle and the local value of the bounce averaged Daa diffusion coefficient. The final DLL associated with pitch angle scattering is then obtained by drift averaging. We show initial results of computed DLL coefficients and simulations using the DREAM diffusion code. The results are compared with Phase Space Densities measured with the recently launched Van Allen Probes.

  10. Electron temperature anisotropy modeling and its effect on anisotropy-magnetic field coupling in an underdense laser heated plasma

    Energy Technology Data Exchange (ETDEWEB)

    Morreeuw, J.P.; Dubroca, B. [CEA Centre d' Etudes Scientifiques et Techniques d' Aquitaine, 33 - Le Barp (France); Sangam, A.; Dubroca, B.; Charrier, P.; Tikhonchuk, V.T. [Bordeaux-1 Univ., CELIA, 33 - Talence (France); Sangam, A.; Dubroca, B.; Charrier, P. [Bordeaux-1 Univ., MAB, 33 - Talence (France)

    2006-06-15

    The laser interaction with an underdense plasma leads to an anisotropic laser heating of electrons. This temperature anisotropy gradient in turn is the source of an early magnetic field, which has an important effect on the plasma evolution, due to the thermal flux reduction. We describe the temperature anisotropy by an evolution equation including the anisotropy-magnetic field coupling and observe a rather efficient magnetic field generation. However at high anisotropy levels, a small-scale instability emerges, leading to a serious problem in numerical calculations. We introduce the kinetics effects, which fix the problem by the anisotropy diffusion through the heat flux tensor. A constant-coefficient Fokker-Planck model in the 2-dimensional geometry allows us to derive an anisotropy diffusion term. The diffusion coefficient is fitted from the kinetic theory of the collisional anisotropic (Weibel) instability growth rate. Such an anisotropy diffusion term wipes out the unphysical instability without any undesirable smoothing. This diffusion along with the viscosity term leads also to a quite good restitution of the Weibel instability growth rate and to the short wavelength cutoff, even in a weakly collisional situation. This allows us to use such a model to predict the emergence of the Weibel instability as well as its saturation. (authors)

  11. Relationship between electrical conductivity anisotropy and fabric anisotropy in granular materials during drained triaxial compressive tests: a numerical approach

    Science.gov (United States)

    Niu, Qifei; Revil, André; Li, Zhaofeng; Wang, Yu-Hsing

    2017-07-01

    The anisotropy of granular media and its evolution during shearing are important aspects required in developing physics-based constitutive models in Earth sciences. The development of relationships between geoelectrical properties and the deformation of porous media has applications to the monitoring of faulting and landslides. However, such relationships are still poorly understood. In this study, we first investigate the definition of the electrical conductivity anisotropy tensor of granular materials in presence of surface conductivity of the grains. Fabric anisotropy is related to the components of the fabric tensor. We define an electrical anisotropy factor based on the Archie's exponent second-order symmetric tensor m of granular materials. We use numerical simulations to confirm a relationship between the evolution of electrical and fabric anisotropy factors during shearing. To realize the simulations, we build a virtual laboratory in which we can easily perform synthetic experiments. We first simulate drained compressive triaxial tests of loose and dense granular materials (porosity 0.45 and 0.38, respectively) using the discrete element method. Then, the electrical conductivity tensor of a set of deformed synthetic samples is computed using the finite-difference method. The numerical results show that shear strains are responsible for a measurable anisotropy in the bulk conductivity of granular media. The observed electrical anisotropy response, during shearing, is distinct for dense and loose synthetic samples. Electrical and fabric anisotropy factors exhibit however a unique linear correlation, regardless of the shear strain and the initial state (porosity) of the synthetic samples. The practical implication of this finding confirms the usefulness of the electrical conductivity method in studying the fabric tensor of granular media. This result opens the door in using time-lapse electrical resistivity to study non-intrusively the evolution of anisotropy

  12. A sensitive fluorescence anisotropy method for detection of lead (II) ion by a G-quadruplex-inducible DNA aptamer

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Dapeng [State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085 (China); Yin, Lei; Meng, Zihui [School of Chemical Engineering and Environment, Beijing Institute of Technology, Beijing, 100081 (China); Yu, Anchi [Department of Chemistry, Renmin University of China, Beijing, 100872 (China); Guo, Lianghong [State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085 (China); Wang, Hailin, E-mail: hlwang@rcees.ac.cn [State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085 (China)

    2014-02-17

    Graphical abstract: -- Highlights: •A fluorescence anisotropy approach for detection of Pb{sup 2+} was developed. •The strategy was based on binding-induced allosteric conformational change of aptamer probe. •The sensing mechanism was established by testing the photoinduced electron transfer interaction. -- Abstract: Sensitive and selective detection of Pb{sup 2+} is of great importance to both human health and environmental protection. Here we propose a novel fluorescence anisotropy (FA) approach for sensing Pb{sup 2+} in homogeneous solution by a G-rich thrombin binding aptamer (TBA). The TBA labeled with 6-carboxytetramethylrhodamine (TMR) at the seventh thymine nucleotide was used as a fluorescent probe for signaling Pb{sup 2+}. It was found that the aptamer probe had a high FA in the absence of Pb{sup 2+}. This is because the rotation of TMR is restricted by intramolecular interaction with the adjacent guanine bases, which results in photoinduced electron transfer (PET). When the aptamer probe binds to Pb{sup 2+} to form G-quadruplex, the intramolecular interaction should be eliminated, resulting in faster rotation of the fluorophore TMR in solution. Therefore, FA of aptamer probe is expected to decrease significantly upon binding to Pb{sup 2+}. Indeed, we observed a decrease in FA of aptamer probe upon Pb{sup 2+} binding. Circular dichroism, fluorescence spectra, and fluorescence lifetime measurement were used to verify the reliability and reasonability of the sensing mechanism. By monitoring the FA change of the aptamer probe, we were able to real-time detect binding between the TBA probe and Pb{sup 2+}. Moreover, the aptamer probe was exploited as a recognition element for quantification of Pb{sup 2+} in homogeneous solution. The change in FA showed a linear response to Pb{sup 2+} from 10 nM to 2.0 μM, with 1.0 nM limit of detection. In addition, this sensing system exhibited good selectivity for Pb{sup 2+} over other metal ions. The method is simple

  13. On the interactions between energetic electrons and lightning whistler waves observed at high L-shells on Van Allen Probes

    Science.gov (United States)

    Zheng, H.; Holzworth, R. H., II; Brundell, J. B.; Hospodarsky, G. B.; Jacobson, A. R.; Fennell, J. F.; Li, J.

    2017-12-01

    Lightning produces strong broadband radio waves, called "sferics", which propagate in the Earth-ionosphere waveguide and are detected thousands of kilometers away from their source. Global real-time detection of lightning strokes including their time, location and energy, is conducted with the World Wide Lightning Location Network (WWLLN). In the ionosphere, these sferics couple into very low frequency (VLF) whistler waves which propagate obliquely to the Earth's magnetic field. A good match has previously been shown between WWLLN sferics and Van Allen Probes lightning whistler waves. It is well known that lightning whistler waves can modify the distribution of energetic electrons in the Van Allen belts by pitch angle scattering into the loss cone, especially at low L-Shells (referred to as LEP - Lightning-induced Electron Precipitation). It is an open question whether lightning whistler waves play an important role at high L-shells. The possible interactions between energetic electrons and lightning whistler waves at high L-shells are considered to be weak in the past. However, lightning is copious, and weak pitch angle scattering into the drift or bounce loss cone would have a significant influence on the radiation belt populations. In this work, we will analyze the continuous burst mode EMFISIS data from September 2012 to 2016, to find out lightning whistler waves above L = 3. Based on that, MAGEIS data are used to study the related possible wave-particle interactions. In this talk, both case study and statistical analysis results will be presented.

  14. VLF waves from ground-based transmitters observed by the Van Allen Probes: Statistical model and effects on plasmaspheric electrons

    Science.gov (United States)

    Ma, Qianli; Mourenas, Didier; Li, Wen; Artemyev, Anton; Thorne, Richard M.

    2017-07-01

    Whistler mode very low frequency (VLF) waves from powerful ground-based transmitters can resonantly scatter energetic plasmaspheric electrons and precipitate them into the atmosphere. A comprehensive 4 year statistics of Van Allen Probes measurements is carried out to assess their consequences on the dynamics of the inner radiation belt and slot region. Statistical models of the measured wave electric field power and of the inferred full wave magnetic amplitude are provided as a function of L, magnetic local time, season, and Kp over L = 1-3, revealing the localization of VLF wave intensity and its variation with geomagnetic activity over 2012-2016. Since this VLF wave model can be directly used together with existing hiss and lightning-generated wave models in radiation belt simulation codes, we perform numerical calculations of the corresponding quasi-linear pitch angle diffusion rates, allowing us to demonstrate the crucial role played by VLF waves from transmitters in energetic electron loss at L < 2.5.

  15. Transient electronic anisotropy in overdoped NaF e1 -xC oxAs superconductors

    Science.gov (United States)

    Liu, Shenghua; Zhang, Chunfeng; Deng, Qiang; Wen, Hai-hu; Li, Jian-xin; Chia, Elbert E. M.; Wang, Xiaoyong; Xiao, Min

    2018-01-01

    By combining polarized pump-probe spectroscopic and Laue x-ray diffraction measurements, we have observed nonequivalent transient optical responses with the probe beam polarized along the x and y axes in overdoped NaF e1 -xC oxAs superconductors. Such transient anisotropic behavior has been uncovered in the tetragonal phase with the doping level and temperature range far from the borders of static nematic phases. The measured transient anisotropy can be well explained as a result of nematic fluctuation driven by an orbital order with energy splitting of the dx z- and dy z-dominant bands. In addition, the doping level dependence and the pressure effect of the crossover temperature show significant differences between the transient nematic fluctuation and static nematic phase, implying spin and orbital orders may play different roles in static and transient nematic behaviors.

  16. Changes in reflectance anisotropy of wheat crop during different phenophases

    Science.gov (United States)

    Lunagaria, Manoj M.; Patel, Haridas R.

    2017-04-01

    The canopy structure of wheat changes significantly with growth stages and leads to changes in reflectance anisotropy. Bidirectional reflectance distribution function characterises the reflectance anisotropy of the targets, which can be approximated. Spectrodirectional reflectance measurements on wheat crop were acquired using a field goniometer system. The bidirectional reflectance spectra were acquired at 54 view angles to cover the hemispheric span up to 60° view zenith. The observations were made during early growth stages till maturity of the crop. The anisotropy was not constant for all wavelengths and anisotropic factors clearly revealed spectral dependence, which was more pronounced in near principal plane. In near infrared, wheat canopy expressed less reflectance anisotropy because of higher multiple scattering. The broad hotspot signature was noticeable in reflectance of canopy whenever view and solar angles were close. Distinct changes in bidirectional reflectance distribution function were observed during booting to flowering stages as the canopy achieves more uniformity, height and head emergence. The function clearly reveals bowl shape during heading to early milking growth stages of the crop. Late growth stages show less prominent gap and shadow effects. Anisotropy index revealed that wheat exhibits changes in reflectance anisotropy with phenological development and with spectral bands.

  17. Cosmic microwave background anisotropies in multiconnected flat spaces

    International Nuclear Information System (INIS)

    Riazuelo, Alain; Weeks, Jeffrey; Uzan, Jean-Philippe; Lehoucq, Roland; Luminet, Jean-Pierre

    2004-01-01

    This article investigates the signature of the seventeen multiconnected flat spaces in cosmic microwave background (CMB) maps. For each such space it recalls a fundamental domain and a set of generating matrices, and then goes on to find an orthonormal basis for the set of eigenmodes of the Laplace operator on that space. The basis eigenmodes are expressed as linear combinations of eigenmodes of the simply connected Euclidean space. A preceding work, which provides a general method for implementing multiconnected topologies in standard CMB codes, is then applied to simulate CMB maps and angular power spectra for each space. Unlike in the 3-torus, the results in most multiconnected flat spaces depend on the location of the observer. This effect is discussed in detail. In particular, it is shown that the correlated circles on a CMB map are generically not back to back, so that negative search of back-to-back circles in the Wilkinson Microwave Anisotropy Probe data does not exclude a vast majority of flat or nearly flat topologies

  18. Geodynamic Constraints on the Sources of Seismic Anisotropy Beneath Madagascar

    Science.gov (United States)

    Rajaonarison, T. A.; Stamps, D. S.; Fishwick, S.

    2017-12-01

    The rheological structure of the lithosphere-asthenosphere system controls the degree in which the mantle drives surface motions. Seismic anisotropy is a proxy to infer information about previous tectonic events imprinted in lithospheric structures and/or asthenospheric flow pattern in regions absent of active volcanism, however, distinguishing between the shallow and deeper sources, respectively, remains ambiguous. Madagascar is an ideal natural laboratory to study the sources of anisotropy and the rheological implications for lithosphere-asthenosphere system because 1) active volcanism is minimal or absent, 2) there are well-exposed tectonic fabrics for comparison, and 3) numerous geological and geophysical observations provides evidence of present-day tectonic activities. Recent studies suggest new seismic anisotropy observations in southern Madagascar are sourced from both fossilized lithospheric structure and asthenospheric flow driven by rigid lithospheric plate motion. In this work we compare geodynamic simulations of the lithosphere-asthenosphere system with seismic anisotropy data set that includes all of Madagascar. We use the numerical code Advanced Solver for Problems in Earth's ConvecTion (ASPECT) to calculate instantaneous deformation in the lithosphere and edge-driven convective flow in the asthenosphere accounting for variations in buoyancy forces and temperature dependent viscosity. The initial temperature conditions are based on interpretations from high resolution regional surface wave tomography. We assume visco-plastic rheology for a uniform crust, dislocation creep for a laterally varying mantle lithospheric structure, and diffusion creep for the asthenosphere. To test for the source of anisotropy we compare our velocity solution azimuths with azimuths of anisotropy at 25 km depth intervals. Calculated asthenospheric flow aligns with measured seismic anisotropy with a 15° WRMS at 175 km depth and possibly down to 250 km suggesting the

  19. Probing the Boundaries of the Heliosphere Using Observations of the Polar ENA Flux from IBEX and Cassini/INCA

    Science.gov (United States)

    Reisenfeld, D. B.; Janzen, P. H.; Bzowski, M.; Dialynas, K.; Funsten, H. O.; Fuselier, S. A.; Galli, A.; Kubiak, M. A.; McComas, D. J.; Schwadron, N.; Sokol, J. M.

    2016-12-01

    The IBEX Mission has been collecting ENAs from the outer heliosphere for nearly eight years, or three-quarters of a solar cycle. In that time, we have observed clear evidence of the imprint of the solar cycle in the time variation in the ENA flux. The most detailed of such studies has focused on the polar ENA flux observed by IBEX-Hi, as the IBEX spacecraft attitude allows for continuous coverage of the ENA flux incident from the ecliptic poles (Reisenfeld et al. 2012, 2016). By time correlating the ENA-derived heliosheath pressure to the observed 1 AU dynamic pressure, we can estimate the distance to the ENA source region. We can further derive the thickness of the ENA-producing region (presumably the inner heliosheath) by assuming pressure balance at the termination shock (TS). This requires using the 1 AU observations to derive the dynamic pressure at the TS shock by use of a mass-loaded solar wind propagation model (Schwadron et al. 2011), and by integrating ENA observations across all energies that significantly contribute to the heliosheath pressure. This means including polar ENA observations from not only IBEX-Hi, but from IBEX-Lo and Cassini/INCA, spanning an energy range of 15 eV to 40 keV. We will present our latest polar ENA observations and estimates for the distance to the TS and the thickness of the heliosheath.

  20. Characterizing coronal structure: Combining remote sensing observations with global MHD modeling to make predictions for Parker Solar Probe and Solar Orbiter missions

    Science.gov (United States)

    Chhiber, R.; Usmanov, A. V.; Matthaeus, W. H.; DeForest, C. E.; Parashar, T.; Goldstein, M. L.

    2017-12-01

    As the solar plasma flows out from the corona and transitions into the solar wind, it transforms from a magnetically structured, subsonic, and sub-Alfvénic regime into a supersonic and super-Alfvénic flow dominated by hydrodynamics. Recent analysis of remote imaging observations in solar minimum conditions by DeForest et al. (2016) have described the early stages of this transition. Here we extend this analysis to global magnetohydrodynamics simulation of the corona and solar wind based on inner boundary conditions that emulate solar minimum, in anticipation of the first phase of Parker Solar Probe (PSP) observations, which are expected during solar minimum as well. Taken together with the imaging analysis, the simulation results provide more detailed expectations for locations of the Alfvén critical surface and the first plasma beta unity surface moving from the corona into the dynamically active solar wind. The turbulence parameters computed from the simulations also enable estimations of the characteristic scales at which in-situ turbulence may influence the dynamics of the solar wind. Estimations of relevant parameters along a simulated PSP trajectory is presented. This multi-faceted approach may be useful in the context of the upcoming Parker Solar Probe and Solar Orbiter missions, which will explore, for the first time, this transition in the inner heliosphere.

  1. Dynamical anisotropy of the optical propagation paths

    Science.gov (United States)

    Arsenyan, Tatiana I.; Pisklin, Maksim V.; Suhareva, Natalia A.; Zotov, Aleksey M.

    2015-11-01

    Dynamics of laser beam intensity profile spatial modulations over a model tropospheric path with the controlled meteorological parameters was studied. Influence of the underlying surface temperature as well as the side wind load were considered. The increase of dynamic anisotropic disturbances saturation with the path length was observed. Spatio-temporal correlation characteristics of the directivity pattern in the signal beam registration plane were obtained. Proposed method of the experimental samples analysis on the base of chronogram with the following definition of the dynamic structure tensors array allows to estimate local and averaged projections of the flow velocities over the chosen spatio-temporal region and to restore their geometry in the zone of intersection with the signal beam. Additional characteristics suggested for the diagonalized local structure tensors such as local energy capacity and local structuredness are informative for the estimation of the inhomogeneities spatial dimensions, time of access through the section considered, the dynamics of energetic jets. The concepts of rotational and translational dynamic anisotropy are introduced to discriminate the types of the changes of the local ellipsoids axes orientation as well as their values. Rotational anisotropy shows itself in the changes of the local ellipsoids orientation, thus characterizing the illumination variation over the beam cross-section. Translational anisotropy describes the difference between the axes values for local ellipsoids.

  2. Probing Twisted Magnetic Field Using Microwave Observations in an M Class Solar Flare on 11 February, 2014

    Science.gov (United States)

    Sharykin, I. N.; Kuznetsov, A. A.; Myshyakov, I. I.

    2018-02-01

    This work demonstrates the possibility of magnetic-field topology investigations using microwave polarimetric observations. We study a solar flare of GOES M1.7 class that occurred on 11 February, 2014. This flare revealed a clear signature of spatial inversion of the radio-emission polarization sign. We show that the observed polarization pattern can be explained by nonthermal gyrosynchrotron emission from the twisted magnetic structure. Using observations of the Reuven Ramaty High Energy Solar Spectroscopic Imager, Nobeyama Radio Observatory, Radio Solar Telescope Network, and Solar Dynamics Observatory, we have determined the parameters of nonthermal electrons and thermal plasma and identified the magnetic structure where the flare energy release occurred. To reconstruct the coronal magnetic field, we use nonlinear force-free field (NLFFF) and potential magnetic-field approaches. Radio emission of nonthermal electrons is simulated by the GX Simulator code using the extrapolated magnetic field and the parameters of nonthermal electrons and thermal plasma inferred from the observations; the model radio maps and spectra are compared with observations. We have found that the potential-magnetic-field approach fails to explain the observed circular polarization pattern; on the other hand, the Stokes-V map is successfully explained by assuming nonthermal electrons to be distributed along the twisted magnetic structure determined by the NLFFF extrapolation approach. Thus, we show that the radio-polarization maps can be used for diagnosing the topology of the flare magnetic structures where nonthermal electrons are injected.

  3. Simultaneous determination of glycols based on fluorescence anisotropy

    International Nuclear Information System (INIS)

    Garcia Sanchez, F.; Navas Diaz, A.; Lopez Guerrero, M.M.

    2007-01-01

    Simultaneous determination of non-fluorescent glycols in mixtures without separation or chemical transformation steps is described. Two methods based in the measure of fluorescence anisotropy of a probe such as fluorescein dissolved in the analyte or analyte mixtures are described. In the first method, the anisotropy spectra of pure and mixtures of analytes are used to quantitative determination (if the fluorophor concentration is in a range where fluorescence intensity is proportional to concentration). In the second method, a calibration curve anisotropy-concentration based on the application of the Perrin equation is established. The methods presented here are capable of directly resolving binary mixtures of non-fluorescent glycols on the basis of differences on the fluorescence anisotropy of a fluorescence tracer. Best analytical performances were obtained by application of the method based on Perrin equation. This method is simple, rapid and allows the determination of mixtures of glycols with reasonable accuracy and precision. Detection limits are limited by the quantum yield and anisotropy values of the tracer in the solvents. Recovery values are related to the differences in anisotropy values of the tracer in the pure solvents. Mixtures of glycerine/ethylene glycol (GL/EG), ethylene glycol/1,2-propane diol (EG/1,2-PPD) and polyethylene glycol 400/1,2-propane diol (PEG 400/1,2-PPD) were analysed and recovery values are within 95-120% in the Perrin method. Relative standard deviation are in the range 1.3-2.9% and detection limits in the range 3.9-8.9%

  4. Solar-wind predictions for the Parker Solar Probe orbit. Near-Sun extrapolations derived from an empirical solar-wind model based on Helios and OMNI observations

    Science.gov (United States)

    Venzmer, M. S.; Bothmer, V.

    2018-03-01

    Context. The Parker Solar Probe (PSP; formerly Solar Probe Plus) mission will be humanitys first in situ exploration of the solar corona with closest perihelia at 9.86 solar radii (R⊙) distance to the Sun. It will help answer hitherto unresolved questions on the heating of the solar corona and the source and acceleration of the solar wind and solar energetic particles. The scope of this study is to model the solar-wind environment for PSPs unprecedented distances in its prime mission phase during the years 2018 to 2025. The study is performed within the Coronagraphic German And US SolarProbePlus Survey (CGAUSS) which is the German contribution to the PSP mission as part of the Wide-field Imager for Solar PRobe. Aim. We present an empirical solar-wind model for the inner heliosphere which is derived from OMNI and Helios data. The German-US space probes Helios 1 and Helios 2 flew in the 1970s and observed solar wind in the ecliptic within heliocentric distances of 0.29 au to 0.98 au. The OMNI database consists of multi-spacecraft intercalibrated in situ data obtained near 1 au over more than five solar cycles. The international sunspot number (SSN) and its predictions are used to derive dependencies of the major solar-wind parameters on solar activity and to forecast their properties for the PSP mission. Methods: The frequency distributions for the solar-wind key parameters, magnetic field strength, proton velocity, density, and temperature, are represented by lognormal functions. In addition, we consider the velocity distributions bi-componental shape, consisting of a slower and a faster part. Functional relations to solar activity are compiled with use of the OMNI data by correlating and fitting the frequency distributions with the SSN. Further, based on the combined data set from both Helios probes, the parameters frequency distributions are fitted with respect to solar distance to obtain power law dependencies. Thus an empirical solar-wind model for the inner

  5. Limits on the ions temperature anisotropy in turbulent intracluster medium

    Energy Technology Data Exchange (ETDEWEB)

    Santos-Lima, R. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Potsdam Univ. (Germany). Inst. fuer Physik und Astronomie; Univ. de Sao Paulo (Brazil). Inst. de Astronomia, Geofisica e Ciencias Atmosfericas; Yan, H. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Potsdam Univ. (Germany). Inst. fuer Physik und Astronomie; Gouveia Dal Pino, E.M. de [Univ. de Sao Paulo (Brazil). Inst. de Astronomia, Geofisica e Ciencias Atmosfericas; Lazarian, A. [Wisconsin Univ., Madison, WI (United States). Dept. of Astronomy

    2016-05-15

    Turbulence in the weakly collisional intracluster medium of galaxies (ICM) is able to generate strong thermal velocity anisotropies in the ions (with respect to the local magnetic field direction), if the magnetic moment of the particles is conserved in the absence of Coulomb collisions. In this scenario, the anisotropic pressure magnetohydrodynamic (AMHD) turbulence shows a very different statistical behaviour from the standard MHD one and is unable to amplify seed magnetic fields, in disagreement with previous cosmological MHD simulations which are successful to explain the observed magnetic fields in the ICM. On the other hand, temperature anisotropies can also drive plasma instabilities which can relax the anisotropy. This work aims to compare the relaxation rate with the growth rate of the anisotropies driven by the turbulence. We employ quasilinear theory to estimate the ions scattering rate due to the parallel firehose, mirror, and ion-cyclotron instabilities, for a set of plasma parameters resulting from AMHD simulations of the turbulent ICM. We show that the ICM turbulence can sustain only anisotropy levels very close to the instabilities thresholds. We argue that the AMHD model which bounds the anisotropies at the marginal stability levels can describe the Alfvenic turbulence cascade in the ICM.

  6. What have we learnt from Wilkinson microwave anisotropy probe?

    Indian Academy of Sciences (India)

    data: the temperature-polarization correlation, correlations with large scale structure, the large-scale power deficit and its implications, and the search for non-Gaussianity. Keywords. Cosmology; cosmic microwave background. PACS Nos 95.85.Bh; 98.80.Es. 1. What makes the WMAP data so special? Just over a year ago, ...

  7. Magnetic dispersion and anisotropy in multiferroic BiFeO3

    Energy Technology Data Exchange (ETDEWEB)

    Matsuda, Masaaki [ORNL; Fishman, Randy Scott [ORNL; Hong, Tao [ORNL; Lee, C. H. [AIST, Japan; Ushiyama, T. [AIST, Japan; Yanagisawa, Y. [AIST, Japan; Tomioka, Y. [AIST, Japan; Ito, T. [AIST, Japan

    2012-01-01

    We have determined the full magnetic dispersion relations of multiferroic BiFeO3. In particular, two excitation gaps originating from magnetic anisotropies have been clearly observed. The direct observation of the gaps enables us to accurately determine the Dzyaloshinskii-Moriya (DM) interaction and the single ion anisotropy. The DM interaction supports a sizable magneto-electric coupling in this compound.

  8. What Do the Hitomi Observations Tell Us About the Turbulent Velocities in the Perseus Cluster? Probing the Velocity Field with Mock Observations

    Science.gov (United States)

    ZuHone, J. A.; Miller, E. D.; Bulbul, E.; Zhuravleva, I.

    2018-02-01

    Hitomi made the first direct measurements of galaxy cluster gas motions in the Perseus cluster, which implied that its core is fairly “quiescent,” with velocities less than ∼200 km s‑1, despite the presence of an active galactic nucleus and sloshing cold fronts. Building on previous work, we use synthetic Hitomi/X-ray Spectrometer (SXS) observations of the hot plasma of a simulated cluster with sloshing gas motions and varying viscosity to analyze its velocity structure in a similar fashion. We find that sloshing motions can produce line shifts and widths similar to those measured by Hitomi. We find these measurements are unaffected by the value of the gas viscosity, since its effects are only manifested clearly on angular scales smaller than the SXS ∼1‧ PSF. The PSF biases the line shift of regions near the core as much as ∼40–50 km s‑1, so it is crucial to model this effect carefully. We also infer that if sloshing motions dominate the observed velocity gradient, Perseus must be observed from a line of sight that is somewhat inclined from the plane of these motions, but one that still allows the spiral pattern to be visible. Finally, we find that assuming isotropy of motions can underestimate the total velocity and kinetic energy of the core in our simulation by as much as ∼60%. However, the total kinetic energy in our simulated cluster core is still less than 10% of the thermal energy in the core, in agreement with the Hitomi observations.

  9. Voltage Control of Magnetic Anisotropy

    Science.gov (United States)

    Hao, Guanhua; Cao, Shi; Noviasky, Nick; Ilie, Carolina; Sokolov, Andre; Yin, Yuewei; Xu, Xiaoshan; Dowben, Peter

    Pd/Co/Gd2O3/Si heterostructures were fabricated via pulsed laser deposition and e-beam evaporation. Hysteresis loops, obtained by longitudinal magneto-optical Kerr-effect (MOKE) measurements, indicates an initial in-plane magnetic anisotropy. Applying a perpendicular voltage on the sample, the differences between the polar and longitudinal MOKE and anomalous Hall effect data indicates there is a reversible change in magnetic anisotropy, from in-plane to out-of-plane, with applied voltage. Prior work by others suggests that the change in magnetic anisotropy is due to redox reactions at the Co/Gd2O3 interference. Voltage controlled magnetism can result from changing interfacial chemistry and does not always require a magneto-electric coupling tensor.

  10. WIDE-FIELD VLBI OBSERVATIONS OF M31: A UNIQUE PROBE OF THE IONIZED INTERSTELLAR MEDIUM OF A NEARBY GALAXY

    International Nuclear Information System (INIS)

    Morgan, John S.; Argo, Megan K.; Trott, Cathryn M.; Macquart, Jean-Pierre; Miller-Jones, James; Tingay, Steven J.; Deller, Adam; Middelberg, Enno

    2013-01-01

    The Very Long Baseline Array was used at 1.6 GHz to observe a target field 50' in diameter including the core of M31. Novel very long baseline interferometry correlation techniques were used to observe 200 sources simultaneously, of which 16 were detected. We classify all 16 as background active galactic nuclei based on their X-ray properties and arcsecond- and mas-scale morphology. The detected sources were then analyzed for evidence of scatter-broadening due to the ionized interstellar medium (ISM) of M31. The detection of a compact background source only 0.25 kpc projected distance from M31* places a constraint on the extent of any extreme scattering region associated with the center of M31. However, the two sources closest to the core show evidence of scatter broadening consistent with that which would be seen for a compact source if it were observed through the inner disk of our Galaxy, at the inclination of M31. We interpret this as a detection of the ionized ISM of M31 along two lines of sight. With the increases in bandwidth and sensitivity envisaged for future long-baseline interferometers, this should prove to be a remarkably powerful technique for understanding the ionized ISM in external galaxies.

  11. Probing the Hot X-Ray Corona around the Massive Spiral Galaxy, NGC 6753, Using Deep XMM-Newton Observations

    Science.gov (United States)

    Bogdán, Ákos; Bourdin, Hervé; Forman, William R.; Kraft, Ralph P.; Vogelsberger, Mark; Hernquist, Lars; Springel, Volker

    2017-11-01

    X-ray emitting gaseous coronae around massive galaxies are a basic prediction of galaxy formation models. Although the coronae around spiral galaxies offer a fundamental test of these models, observational constraints on their characteristics are still scarce. While the presence of extended hot coronae has been established around a handful of massive spiral galaxies, the short X-ray observations only allowed for measurements of the basic characteristics of the coronae. In this work, we utilize deep XMM-Newton observations of NGC 6753 to explore its extended X-ray corona in unprecedented detail. Specifically, we establish the isotropic morphology of the hot gas, suggesting that it resides in hydrostatic equilibrium. The temperature profile of the gas shows a decrease with an increasing radius: it drops from {kT}≈ 0.7 {keV} in the innermost parts to {kT}≈ 0.4 {keV} at a 50 kpc radius. The temperature map reveals the complex temperature structure of the gas. We study the metallicity distribution of the gas, which is uniform at Z≈ 0.1 Solar. This value is about an order of magnitude lower than that obtained for elliptical galaxies with similar dark matter halo mass, hinting that the hot gas in spiral galaxies predominantly originates from external gas inflows rather than from internal sources. By extrapolating the density profile of the hot gas out to the virial radius, we estimate the total gas mass and derive the total baryon mass of NGC 6753. We conclude that the baryon mass fraction is {f}{{b}}≈ 0.06, implying that about half of the baryons are missing.

  12. Effect of defects, magnetocrystalline anisotropy, and shape anisotropy on magnetic structure of iron thin films by magnetic force microscopy

    Directory of Open Access Journals (Sweden)

    Ke Xu

    2017-05-01

    Full Text Available Microstructures of magnetic materials, including defects and crystallographic orientations, are known to strongly influence magnetic domain structures. Measurement techniques such as magnetic force microscopy (MFM thus allow study of correlations between microstructural and magnetic properties. The present work probes effects of anisotropy and artificial defects on the evolution of domain structure with applied field. Single crystal iron thin films on MgO substrates were milled by Focused Ion Beam (FIB to create different magnetically isolated squares and rectangles in [110] crystallographic orientations, having their easy axis 45° from the sample edge. To investigate domain wall response on encountering non-magnetic defects, a 150 nm diameter hole was created in the center of some samples. By simultaneously varying crystal orientation and shape, both magnetocrystalline anisotropy and shape anisotropy, as well as their interaction, could be studied. Shape anisotropy was found to be important primarily for the longer edge of rectangular samples, which exaggerated the FIB edge effects and provided nucleation sites for spike domains in non-easy axis oriented samples. Center holes acted as pinning sites for domain walls until large applied magnetic fields. The present studies are aimed at deepening the understanding of the propagation of different types of domain walls in the presence of defects and different crystal orientations.

  13. Probing the small-scale structure of the interplanetary medium with high time resolution galactic cosmic ray observations

    Science.gov (United States)

    Jordan, Andrew P.

    Galactic cosmic rays (GCRs) are relativistic charged particles that fill interplanetary and interstellar space. The Sun's magnetic field, carried radially outward by the solar wind (collectively called the interplanetary medium or IPM), is the dominant modulator of GCR fluxes near Earth. GCR variations can uncover IPM structure beyond what single-point IPM measurements reveal. While such research in the past has been successful on larger scales, little work has considered how the IPM affects GCRs on small scales (scales on the order of at most an hour in time or gigameters in space). This dissertation represents the first use of GCR observations to explore the nature of small-scale structure in the IPM, an area of active study. To begin, I test the validity of an important traditional model based on low time resolution observations. This model describes how interplanetary coronal mass ejections (ICMEs), their shocks, and their sheaths create two-step Forbush decreases (Fds) in GCR flux ( Forbush , 1937). I analyze 82 Fds from 1998 to 2006 and discover that the model is too idealized to account for the majority of Fds. Small-scale structure in the sheath of ICMEs appears to be important for creating a variety of time-profiles, instead of only the two steps predicted by the model. Next, I use space-based, high time resolution GCR data to investigate on even smaller scales how ICME sheath structure affects cosmic rays. Because the spacecraft instruments were not designed to detect GCRs, I first show that the space-based data are reliable. In three of the five observed Fds, planar magnetic structures within the ICME sheaths appear to have contributed to the initiation of the decreases. Finally, I explore thirty instances of a newly discovered phenomenon: small-scale local maxima in the GCR flux that occur within ICME sheaths during the initial stages of Fds. I discover that magnetic structure, not turbulence, in ICME sheaths is responsible for the majority of these

  14. Asymmetric beams and CMB statistical anisotropy

    International Nuclear Information System (INIS)

    Hanson, Duncan; Lewis, Antony; Challinor, Anthony

    2010-01-01

    Beam asymmetries result in statistically anisotropic cosmic microwave background (CMB) maps. Typically, they are studied for their effects on the CMB power spectrum, however they more closely mimic anisotropic effects such as gravitational lensing and primordial power asymmetry. We discuss tools for studying the effects of beam asymmetry on general quadratic estimators of anisotropy, analytically for full-sky observations as well as in the analysis of realistic data. We demonstrate this methodology in application to a recently detected 9σ quadrupolar modulation effect in the WMAP data, showing that beams provide a complete and sufficient explanation for the anomaly.

  15. Van Allen Probe observations of drift-bounce resonances with Pc 4 pulsations and wave–particle interactions in the pre-midnight inner magnetosphere

    Directory of Open Access Journals (Sweden)

    G. I. Korotova

    2015-08-01

    Full Text Available We present Van Allen Probe B observations of azimuthally limited, antisymmetric, poloidal Pc 4 electric and magnetic field pulsations in the pre-midnight sector of the magnetosphere from 05:40 to 06:00 UT on 1 May 2013. Oscillation periods were similar for the magnetic and electric fields and proton fluxes. The flux of energetic protons exhibited an energy-dependent response to the pulsations. Energetic proton variations were anticorrelated at medium and low energies. Although we attribute the pulsations to a drift-bounce resonance, we demonstrate that the energy-dependent response of the ion fluxes results from pulsation-associated velocities sweeping energy-dependent radial ion flux gradients back and forth past the spacecraft.

  16. Research support for plasma diagnostics on Elmo Bumpy Torus - development of a multichannel Hall-probe based diamagnetic diagnostic instrument and observation and modeling of EBT electron rings. Final report, October 1, 1982-September 30, 1983

    International Nuclear Information System (INIS)

    Carpenter, K.H.; Booker, R.H.

    1983-10-01

    Use of multiple Hall effect probes is a cost effective way to observe diamagnetic fields from the hot electron rings in the Elmo Bumpy Torus device at several locations simultaneously. A special diagnostic instrument has been developed having six Hall probe channels with the sensitivity and stability needed for the diamagnetic measurements. The instrument uses an AC carrier system with isolation transformers located remotely from the instrument and near the probe locations. Details of instrument design as well as operating instructions for it are included in this report

  17. Probing the Accretion Disk and Central Engine Structure of the NGC 4258 with Suzaku and XMM-Newton Observations

    Science.gov (United States)

    Reynolds, Christopher S.; Nowak, Michael A.; Markoff, Sera; Tueller, Jack; Wilms, Joern; Young, Andrew

    2009-01-01

    We present an X-ray study of the low-luminosity active galactic nucleus (AGN) in NGC 4258 using data from Suzaku, XMM-Newton, and the Swift/Burst Alert Telescope survey. We find that signatures of X-ray reprocessing by cold gas are very weak in the spectrum of this Seyfert-2 galaxy; a weak, narrow fluorescent K(alpha) emission line of cod iron is robustly detected in both the Suzaku and XMM-Newton spectra but at a level much below that of most other Seyfert-2 galaxies. We conclude that the circumnuclear environment of this AGN is very "clean" and lacks the Compton-thick obscuring torus of unified Seyfert schemes. From the narrowness of the iron line, together with evidence of line flux variability between the Suzaku and XMM-Newton observations, we constrain the line emitting region to be between 3 x 10(exp 3)r(sub g) and 4 x 10(exp 4)r(sub g), from the black hole. We show that the observed properties of the iron line can be explained if the line originates from the surface layers of a warped accretion disk. In particular, we present explicit calculations of the expected iron line from a disk warped by Lens-Thirring precession from a misaligned central black hole. Finally, the Suzaku data reveal clear evidence of large amplitude 2-10 keV variability on timescales of 50 ksec and smaller amplitude flares on timescales as short as 5-10 ksec. If associated with accretion disk processes, such rapid variability requires an origin in the innermost regions of the disk (r approx. equals 10(r(sub g) or less). Analysis of the difference spectrum between a high- and low-flux states suggests that the variable component of the X-ray emission is steeper and more absorbed than the average AGN emission, suggesting that the primary X-ray source and absorbing screen have a spatial structure on comparable scales. We note the remarkable similarity between the circumnuclear environment of NGC 4258 and another well studied low-luminosity AGN, M81*.

  18. Exhaustive Study of Cosmic Microwave Background Anisotropies in Quintessential Scenarios

    CERN Document Server

    Brax, P; Riazuelo, A; Brax, Philippe; Martin, Jerome; Riazuelo, Alain

    2000-01-01

    Recent high precision measurements of the CMB anisotropies performed by the BOOMERanG and MAXIMA-1 experiments provide an unmatched set of data allowing to probe different cosmological models. Among these scenarios, motivated by the recent measurements of the luminosity distance versus redshift relation for type Ia supernovae, is the quintessence hypothesis. It consists in assuming that the acceleration of the Universe is due to a scalar field whose final evolution is insensitive to the initial conditions. Within this framework we investigate the cosmological perturbations for two well-motivated potentials: the Ratra-Peebles and the SUGRA tracking potentials. We show that the solutions of the perturbed equations possess an attractor and that, as a consequence, the insensitivity to the initial conditions is preserved at the perturbed level. Then, we study the predictions of these two models for structure formation and CMB anisotropies and investigate the general features of the multipole moments in the presenc...

  19. UV-Induced Anisotropy In CdBr2-CdBr2: Cu Nanostructures

    Directory of Open Access Journals (Sweden)

    El-Naggar A. M.

    2015-09-01

    Full Text Available We have found an occurrence of anisotropy in the nanostructure CdBr2-CdBr2: Cu nanocrystalline films. The film thickness was varied from 4 nm up to 80 nm. The films were prepared by successive deposition of the novel layers onto the basic nanocrystals. The detection of anisotropy was performed by occurrence of anisotropy in the polarized light at 633 nm He-Ne laser wavelength. The occurrence of anisotropy was substantially dependent on the film thickness and the photoinduced power density. Possible mechanisms of the observed phenomena are discussed.

  20. Magnetic alloys with vanishing anisotropies

    International Nuclear Information System (INIS)

    Couderchon, G.

    1991-01-01

    Co-based amorphous alloys and 80 Ni Permalloys have vanishingly-low anisotropies and show the highest permeabilities and lowest losses among commercial magnetic materials. In spit of their different atomic arrangements, these two types of material show close similarities in domain structure and in their temperature and frequency behavior. Information is also given concerning material technology and applications. (orig.)

  1. Probing the mechanism of saccade-associated head movements through observations of head movement propensity and cognition in the elderly.

    Science.gov (United States)

    Thumser, Zachary C; Adams, Nancy L; Lerner, Alan J; Stahl, John S

    2010-05-01

    Humans may accomplish gaze shifts by eye-only saccades or combined eye-head saccades. The mechanisms that determine whether the head moves remain poorly understood. Many observations can be explained if phylogenetically ancient circuits generate eye-head saccades by default and frontal cerebral structures interrupt this synergy when eye-only saccades are preferable. Saccade-associated head movements have been reported to increase in the elderly. To test the hypothesis of frontal inhibition of head movements, we investigated whether the increase is associated with a decline in frontal cognitive function. We measured head movement tendencies and cognition in volunteers aged 61-80. Measures of head movement tendency included the customary range of eye eccentricity, customary range of head eccentricity, range of target eccentricities evoking predominantly eye-only saccades, and two measures of head amplitude variation as a function of target eccentricity. Cognitive measures encompassed verbal fluency, verbal memory, non-verbal memory, and executive function. There was no correlation between cognition and any measure of head movement tendency. We combined these elderly data with measurements of head movements in a group aged 21-67 and found mildly reduced, not increased, head movement tendencies with age. However, when confronted with a task that could be accomplished without moving the head, young subjects were more likely to cease all head movements. While inconclusive regarding the hypothesis of inhibition of saccade-associated head movements by cerebral structures, the results indicate the need to distinguish between mechanisms that define head movement tendencies and mechanisms that adapt head motion to the geometry of a specific task.

  2. Fourier-transform infrared anisotropy in cross and parallel sections of tendon and articular cartilage

    Directory of Open Access Journals (Sweden)

    Bidthanapally Aruna

    2008-10-01

    Full Text Available Abstract Background Fourier Transform Infrared Imaging (FTIRI is used to investigate the amide anisotropies at different surfaces of a three-dimensional cartilage or tendon block. With the change in the polarization state of the incident infrared light, the resulting anisotropic behavior of the tissue structure is described here. Methods Thin sections (6 μm thick were obtained from three different surfaces of the canine tissue blocks and imaged at 6.25 μm pixel resolution. For each section, infrared imaging experiments were repeated thirteen times with the identical parameters except a 15° increment of the analyzer's angle in the 0° – 180° angular space. The anisotropies of amide I and amide II components were studied in order to probe the orientation of the collagen fibrils at different tissue surfaces. Results For tendon, the anisotropy of amide I and amide II components in parallel sections is comparable to that of regular sections; and tendon's cross sections show distinct, but weak anisotropic behavior for both the amide components. For articular cartilage, parallel sections in the superficial zone have the expected infrared anisotropy that is consistent with that of regular sections. The parallel sections in the radial zone, however, have a nearly isotropic amide II absorption and a distinct amide I anisotropy. Conclusion From the inconsistency in amide anisotropy between superficial to radial zone in parallel section results, a schematic model is used to explain the origins of these amide anisotropies in cartilage and tendon.

  3. Study of Ion Temperature Anisotropy Boundaries in the Magnetosheath

    Science.gov (United States)

    Lin, N.; Travnicek, P. M.; McFadden, J. P.; Parks, G. K.; Yoon, P. H.; Johnson, J.; Chaston, C. C.

    2012-12-01

    The magnetosheath plasma often exhibits proton temperature anisotropy which may develop several instabilities. For anisotropy Tperp>Tpara, where Tperp and Tpara are the perpendicular and parallel (to the ambient magnetic field) proton temperatures, respectively, electromagnetic ion cyclotron (EMIC) and mirror mode instabilities can be excited, while for TperpHellinger et al., 2006] with linear theory, by assuming bi-Maxwellian protons, in the form of Tperp/Tpara = 1+ a /(beta_para-beta_0)^b, where a, b, and beta_0 are fitting parameters for the threshold condition of maximum growth rate γmax =10^-3 ωcp, and ωcp is the proton cyclotron frequency. We have used plasma and magnetic field observations from several magnetosheath passes of THEMIS and Cluster spacecraft to examine the anisotropy boundary and compare the observations with the theoretical stability boundary. Three wave parameters |δB||/B0|, |δBperp/B0|, and the magnetic compressibility, δB||^2/( δB||^2+ δBperp^2), are calculated and distributions of their intensities on the Tperp/Tpara vs beta_para plane are examined. The data are shown to cluster around the thresholds of the mirror mode and the EMIC mode. For compressional waves there exist enhancements above the mirror mode threshold, which may indicate evolving process of the magnetosheath unstable plasma. The transverse variations are better constrained by the theoretical EMIC marginal curve. The distributions are notably different compared to previous observations of the solar wind fluctuations, which are enhanced along the temperature anisotropy thresholds of the four instabilities, indicating that the proton temperature anisotropy in the solar wind is constrained by the threshold defined in the above equation. We will discuss the interpretation of the results which may provide observational support or constraints on the theoretical and modeling developments of the marginal condition for the proton temperature anisotropy instabilities in the

  4. Experimental and numerical study of the electrical anisotropy in unidirectional carbon-fiber-reinforced polymer composites

    Science.gov (United States)

    Park, J. B.; Hwang, T. K.; Kim, H. G.; Doh, Y. D.

    2007-02-01

    In this paper, unidirectional CFRP composites are considered as an electrical percolation system, which consists of electrically conductive carbon fibers and electrically nonconductive epoxy resin. Due to the contact behavior of the carbon fibers, CFRP has electrical conductivity in the width direction. Resistance measurements using the DC four-probe and the DC six-probe methods are conducted for the unidirectional CFRP specimens with different fiber volume fractions, i.e. different contact conditions. On the basis of the electrical anisotropy level obtained, the correlation between the measured anisotropy and the electrical ineffective length δec, over which a broken fiber recovers its current carrying capacity and a key parameter in electromechanical modeling of CFRP, is shown experimentally. The empirical relationship between the electrical anisotropy and δec obtained is also reviewed using a numerical calculation method based on the electric circuit theory of Kirchhoff's rule and the Monte Carlo simulation technique.

  5. Initial observations of fine plasma structures at the flank magnetopause with the complex plasma analyzer SCA-1 onboard the Interball Tail Probe

    Directory of Open Access Journals (Sweden)

    O. L. Vaisberg

    Full Text Available The fast plasma analyzer EU-1 of the SCA-1 complex plasma spectrometer is installed onboard the Interball Tail Probe (Interball-1. It provides fast three-dimensional measurements of the ion distribution function on the low-spin-rate Prognoz satellite (about 2min. The EU-1 ion spectrometer with virtual aperture consists of two detectors with 16 E/Q narrow-angle analyzers and electrostatic scanners. This configuration allows one to measure the ion distribution function in three dimensions (over 15 energy steps in 50 eV/Q–5.0 keV/Q energy range in 64 directions in 7.5 s, which makes it independent of the slow rotation speed of the satellite. A description of the instrument and its capabilities is given. We present here the preliminary results of measurements of ions for two cases of the dawn low- and mid-latitude magnetopause crossings. The properties of observed ion structures and their tentative explanation are presented. The 12 September 1995 pass at low latitude at about 90° solar-zenith angle on the dawn side of the magnetosphere is considered in more detail. Dispersive ions are seen at the edge of the magnetopause and at the edges of subsequently observed plasma structures. Changes in ion velocity distribution in plasma structures observed after the first magnetopause crossing suggest that what resembles multiple magnetopause crossings may be plasma blobs penetrating the magnetosphere. Observed variations of plasma parameters near magnetopause structures suggest nonstationary reconnection as the most probable mechanism for observed structures.

  6. Initial observations of fine plasma structures at the flank magnetopause with the complex plasma analyzer SCA-1 onboard the Interball Tail Probe

    Directory of Open Access Journals (Sweden)

    O. L. Vaisberg

    1997-05-01

    Full Text Available The fast plasma analyzer EU-1 of the SCA-1 complex plasma spectrometer is installed onboard the Interball Tail Probe (Interball-1. It provides fast three-dimensional measurements of the ion distribution function on the low-spin-rate Prognoz satellite (about 2min. The EU-1 ion spectrometer with virtual aperture consists of two detectors with 16 E/Q narrow-angle analyzers and electrostatic scanners. This configuration allows one to measure the ion distribution function in three dimensions (over 15 energy steps in 50 eV/Q–5.0 keV/Q energy range in 64 directions in 7.5 s, which makes it independent of the slow rotation speed of the satellite. A description of the instrument and its capabilities is given. We present here the preliminary results of measurements of ions for two cases of the dawn low- and mid-latitude magnetopause crossings. The properties of observed ion structures and their tentative explanation are presented. The 12 September 1995 pass at low latitude at about 90° solar-zenith angle on the dawn side of the magnetosphere is considered in more detail. Dispersive ions are seen at the edge of the magnetopause and at the edges of subsequently observed plasma structures. Changes in ion velocity distribution in plasma structures observed after the first magnetopause crossing suggest that what resembles multiple magnetopause crossings may be plasma blobs penetrating the magnetosphere. Observed variations of plasma parameters near magnetopause structures suggest nonstationary reconnection as the most probable mechanism for observed structures.

  7. The dipole anisotropy of WISE × SuperCOSMOS number counts

    Science.gov (United States)

    Bengaly, C. A. P.; Novaes, C. P.; Xavier, H. S.; Bilicki, M.; Bernui, A.; Alcaniz, J. S.

    2018-01-01

    We probe the isotropy of the Universe with the largest all-sky photometric redshift dataset currently available, namely WISE × SuperCOSMOS. We search for dipole anisotropy of galaxy number counts in multiple redshift shells within the 0.10 origin of the latter discrepancy is unclear, and improved data may be needed to explain it.

  8. Global imaging of the Earth's deep interior: seismic constraints on (an)isotropy, density and attenuation

    NARCIS (Netherlands)

    Trampert, J.; Fichtner, A.

    2013-01-01

    Seismic tomography is the principal tool to probe the deep interior of the Earth. Models of seismic anisotropy induced by crystal alignment provide insight into the underlying convective motion, and variations of density allow us to discriminate between thermal and compositional heterogeneities.

  9. Azimuthal and Radial Seismic Anisotropy Beneath the Baltic Shield

    Science.gov (United States)

    Pedersen, H. A.; Bruneton, M.; Maupin, V.

    2005-12-01

    The SVEKALAPKO passive seismic array in Finland provides us with an exceptional opportunity to study seismic anisotropy in and below the lithosphere in a shield. The array was composed of almost 150 sensors - out of which 46 were broadband - in a regular 2D grid which facilitated high-quality array analysis. We analyse phase velocities of both Love and Rayleigh waves to constrain radial and azimuthal anisotropy. We invert for the anisotropic parameters ξ and Gc on the one hand, and for the percentage of aligned olivine on the other. This latter parametrization of the inverse problem makes it straightforward to quantitatively compare the radial and the azimuthal anisotropies, under the assumption that aligned olivine dominates the anisotropy. The radial anisotropy, for which we have resolution in the lithosphere only, is strong, and can be explained by 40%-60% of the rock being olivine with the a-axis in the horizontal plane, equivalent to values of ξ between 1.09 and 1.14. This radial anisotropy is stronger than observed in shield areas in global models (e.g. Beghein and Trampert, 2004). The azimuthal anisotropy is on the contrary very small in the lithosphere. This indicates that the orientation of the olivine minerals is random within the horizontal plane or that the overall effect across the area is negligible due to different orientations in different domains. Results from body-waves (Plomerová et al., 2005, Vecsey et al., in prep.) would support the latter interpretation. The azimuthal anisotropy as estimated by Rayleigh wave analysis is on the contrary significant below 200-250km depth, and corresponds to approximately 15%-20% of the rock being olivine with the a-axis aligned in direction N20. Xenolith analysis in the area shows that the rheologic lithosphere is at most 250km thick, so we suggest that this observed anisotropy is sub-lithospheric. Interestingly, the fast direction is significantly different from the absolute plate motion of the Baltic

  10. Pump probe spectroscopy of quasiparticle dynamics in cuprate superconductors

    International Nuclear Information System (INIS)

    Segre, Gino P.

    2001-01-01

    Pump probe spectroscopy is used to examine the picosecond response of a BSCCO thin film, and two YBCO crystals in the near infrared. The role of pump fluence and temperature have been closely examined in an effort to clarify the mechanism by which the quasiparticles rejoin the condensate. BSCCO results suggest that the recombination behavior is consistent with the d-wave density of states in that quasiparticles appear to relax to the nodes immediately before they rejoin the condensate. The first substantial investigation of polarized pump probe response in detwinned YBCO crystals is also reported. Dramatic doping dependent anisotropies along the a and b axes are observed in time and temperature resolved studies. Among many results, we highlight the discovery of an anomalous temperature and time dependence of a- axis response in optimally doped YBCO. We also report on the first observation of the photoinduced response in a magnetic field. We find the amplitude of the response, and in some cases, the dynamics considerably changed with the application of a 6T field. Finally, we speculate on two of the many theoretical directions stimulated by our results. We find that the two-fluid model suggests a mechanism to explain how changes at very low energies are visible to a high-energy probe. Also discussed are basic recombination processes which may play a role in the observed decay

  11. Anisotropy of magnetoviscous effect in structure-forming ferrofluids

    Science.gov (United States)

    Sreekumari, Aparna; Ilg, Patrick

    2015-07-01

    The magnetoviscous effect, change in viscosity with change in magnetic field strength, and the anisotropy of the magnetoviscous effect, change in viscosity with orientation of magnetic field, have been a focus of interest for four decades. A satisfactory understanding of the microscopic origin of anisotropy of the magnetoviscous effect in magnetic fluids is still a matter of debate and a field of intense research. Here, we present an extensive simulation study to understand the relation between the anisotropy of the magnetoviscous effect and the underlying change in microstructures of ferrofluids. Our results indicate that field-induced chainlike structures respond very differently depending on their orientation relative to the direction of an externally applied shear flow, which leads to a pronounced anisotropy of viscosity. In this work, we focus on three exemplary values of dipolar interaction strengths which correspond to weak, intermediate, and strong interactions between dipolar colloidal particles. We compare our simulation results with an experimental study on cobalt-based ferrofluids as well as with an existing theoretical model called the chain model. A nonmonotonic behavior in the anisotropy of the magnetoviscous effect is observed with increasing dipolar interaction strength and is explained in terms of microstructure formation.

  12. Van Allen Probes observations of drift-bounce resonance and energy transfer between energetic ring current protons and poloidal Pc4 wave

    Science.gov (United States)

    Oimatsu, S.; Masahito, N.; Takahashi, K.; Yamamoto, K.; Keika, K.; Kletzing, C.; MacDowall, R. J.; Smith, C.; Mitchell, D. G.

    2017-12-01

    Poloidal Pc4 wave and proton flux oscillation due to the drift-bounce resonance are observed in the inner magnetosphere on the dayside near the magnetic equator by the Van Allen Probes spacecraft on 2 March 2014. The flux modulation is observed in the energy range of 67.0 keV to 268.8 keV with the same frequency of poloidal Pc4 wave. We estimate the resonant energy to be 120 keV for pitch angle (α) of 20º-40º or 140º-160º, and 170-180 keV for α=40º-60º or 120º-140º. The drift-bounce resonance theory gives the resonant energy of 110-120 keV, which is consistent with the observation for small α (or large α when α≥90º), but slightly higher than the observation for large α (or small α when α≥90º). We consider that this discrepancy of the resonant energy is due to the drift shell splitting. In order to examine the direction of energy flow between protons and the wave, we calculate the sign of the gradient of proton phase space density (df/dW) in both outbound and inbound paths. Results showed positive gradient in both paths, which means that the energy is transferred from the protons to the wave. During the appearance of poloidal Pc4 wave, the Dst* index shows a sudden increase of 6.7 nT. We estimate the total energy loss of the ring current from the recovery of the Dst* index and the variation of proton flux by the drift-bounce resonance. The estimated energy loss is almost comparable for both cases. Therefore, we suggest that the energy transfer from the ring current protons to the wave via the drift-bounce resonance cause the increase of Dst* index.

  13. Anisotropy in "isotropic diffusion" measurements due to nongaussian diffusion

    DEFF Research Database (Denmark)

    Jespersen, Sune Nørhøj; Olesen, Jonas Lynge; Ianuş, Andrada

    2017-01-01

    Designing novel diffusion-weighted NMR and MRI pulse sequences aiming to probe tissue microstructure with techniques extending beyond the conventional Stejskal-Tanner family is currently of broad interest. One such technique, multidimensional diffusion MRI, has been recently proposed to afford...... model-free decomposition of diffusion signal kurtosis into terms originating from either ensemble variance of isotropic diffusivity or microscopic diffusion anisotropy. This ability rests on the assumption that diffusion can be described as a sum of multiple Gaussian compartments, but this is often...

  14. Field-ball milling induced anisotropy in magnetic particles

    Energy Technology Data Exchange (ETDEWEB)

    Poudyal, Narayan [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States); Altuncevahir, Baki [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States); Chakka, Vamsi [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States); Chen Kanghua [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States); Black, Truman D [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States); Liu, J Ping [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States); Ding, Yong [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States); Wang Zhonglin [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States)

    2004-12-21

    Nd{sub 2}Fe{sub 14}B and Sm{sub 2}Co{sub 17} particles of submicrometre sizes have been prepared by ball milling in a magnetic field. Structural and magnetic characterization reveal that these submicrometre particles milled in a magnetic field, consisting of nanosize grains, exhibit strong magnetic anisotropy compared with the particles milled without a magnetic field. Based on in situ observations of the field-ball milling in a transparent container, the mechanism of field-induced anisotropy in the nanostructured hard magnetic particles is discussed. (rapid communication)

  15. Friction anisotropy-driven domain imaging on exfoliated monolayer graphene.

    Science.gov (United States)

    Choi, Jin Sik; Kim, Jin-Soo; Byun, Ik-Su; Lee, Duk Hyun; Lee, Mi Jung; Park, Bae Ho; Lee, Changgu; Yoon, Duhee; Cheong, Hyeonsik; Lee, Ki Ho; Son, Young-Woo; Park, Jeong Young; Salmeron, Miquel

    2011-07-29

    Graphene produced by exfoliation has not been able to provide an ideal graphene with performance comparable to that predicted by theory, and structural and/or electronic defects have been proposed as one cause of reduced performance. We report the observation of domains on exfoliated monolayer graphene that differ by their friction characteristics, as measured by friction force microscopy. Angle-dependent scanning revealed friction anisotropy with a periodicity of 180° on each friction domain. The friction anisotropy decreased as the applied load increased. We propose that the domains arise from ripple distortions that give rise to anisotropic friction in each domain as a result of the anisotropic puckering of the graphene.

  16. Magnetic Alignment of Block Copolymer Microdomains by Intrinsic Chain Anisotropy.

    Science.gov (United States)

    Rokhlenko, Yekaterina; Gopinadhan, Manesh; Osuji, Chinedum O; Zhang, Kai; O'Hern, Corey S; Larson, Steven R; Gopalan, Padma; Majewski, Paweł W; Yager, Kevin G

    2015-12-18

    We examine the role of intrinsic chain susceptibility anisotropy in magnetic field directed self-assembly of a block copolymer using in situ x-ray scattering. Alignment of a lamellar mesophase is observed on cooling across the disorder-order transition with the resulting orientational order inversely proportional to the cooling rate. We discuss the origin of the susceptibility anisotropy, Δχ, that drives alignment and calculate its magnitude using coarse-grained molecular dynamics to sample conformations of surface-tethered chains, finding Δχ≈2×10^{-8}. From field-dependent scattering data, we estimate that grains of ≈1.2  μm are present during alignment. These results demonstrate that intrinsic anisotropy is sufficient to support strong field-induced mesophase alignment and suggest a versatile strategy for field control of orientational order in block copolymers.

  17. Ion temperature anisotropy limitation in high beta plasmas

    International Nuclear Information System (INIS)

    Scime, Earl E.; Keiter, Paul A.; Balkey, Matthew M.; Boivin, Robert F.; Kline, John L.; Blackburn, Melanie; Gary, S. Peter

    2000-01-01

    Measurements of parallel and perpendicular ion temperatures in the Large Experiment on Instabilities and Anisotropies (LEIA) space simulation chamber display an inverse correlation between the upper bound on the ion temperature anisotropy and the parallel ion beta (β=8πnkT/B 2 ). Fluctuation measurements indicate the presence of low frequency, transverse, electromagnetic waves with wave numbers and frequencies that are consistent with predictions for Alfven Ion Cyclotron instabilities. These observations are also consistent with in situ spacecraft measurements in the Earth's magnetosheath and with a theoretical/computational model that predicts that such an upper bound on the ion temperature anisotropy is imposed by scattering from enhanced fluctuations due to growth of the Alfven ion cyclotron instability. (c) 2000 American Institute of Physics

  18. Anisotropy of domain wall resistance

    Science.gov (United States)

    Viret; Samson; Warin; Marty; Ott; Sondergard; Klein; Fermon

    2000-10-30

    The resistive effect of domain walls in FePd films with perpendicular anisotropy was studied experimentally as a function of field and temperature. The films were grown directly on MgO substrates, which induces an unusual virgin magnetic configuration composed of 60 nm wide parallel stripe domains. This allowed us to carry out the first measurements of the anisotropy of domain wall resistivity in the two configurations of current perpendicular and parallel to the walls. At 18 K, we find 8.2% and 1.3% for the domain wall magnetoresistance normalized to the wall width (8 nm) in these two respective configurations. These values are consistent with the predictions of Levy and Zhang.

  19. Artificial anisotropy and polarizing filters.

    Science.gov (United States)

    Flory, François; Escoubas, Ludovic; Lazaridès, Basile

    2002-06-01

    The calculated spectral transmittance of a multilayer laser mirror is used to determine the effective index of the single layer equivalent to the multilayer stack. We measure the artificial anisotropy of photoresist thin films whose structure is a one-dimensional, subwavelength grating obtained from interference fringes. The limitation of the theory of the first-order effective index homogenization is discussed. We designed normal-incidence, polarizing coating and a polarization rotator by embedding anisotropic films in simple multilayer structures.

  20. The large scale microwave background anisotropy in decaying particle cosmology

    International Nuclear Information System (INIS)

    Panek, M.

    1987-06-01

    We investigate the large-scale anisotropy of the microwave background radiation in cosmological models with decaying particles. The observed value of the quadrupole moment combined with other constraints gives an upper limit on the redshift of the decay z/sub d/ < 3-5. 12 refs., 2 figs

  1. Solar energetic particle anisotropies and insights into particle transport

    Energy Technology Data Exchange (ETDEWEB)

    Leske, R. A., E-mail: ral@srl.caltech.edu; Cummings, A. C.; Cohen, C. M. S.; Mewaldt, R. A.; Labrador, A. W.; Stone, E. C. [California Institute of Technology, Pasadena, CA 91125 (United States); Wiedenbeck, M. E. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Christian, E. R.; Rosenvinge, T. T. von [NASA/Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2016-03-25

    As solar energetic particles (SEPs) travel through interplanetary space, their pitch-angle distributions are shaped by the competing effects of magnetic focusing and scattering. Measurements of SEP anisotropies can therefore reveal information about interplanetary conditions such as magnetic field strength, topology, and turbulence levels at remote locations from the observer. Onboard each of the two STEREO spacecraft, the Low Energy Telescope (LET) measures pitch-angle distributions for protons and heavier ions up to iron at energies of about 2-12 MeV/nucleon. Anisotropies observed using LET include bidirectional flows within interplanetary coronal mass ejections, sunward-flowing particles when STEREO was magnetically connected to the back side of a shock, and loss-cone distributions in which particles with large pitch angles underwent magnetic mirroring at an interplanetary field enhancement that was too weak to reflect particles with the smallest pitch angles. Unusual oscillations in the width of a beamed distribution at the onset of the 23 July 2012 SEP event were also observed and remain puzzling. We report LET anisotropy observations at both STEREO spacecraft and discuss their implications for SEP transport, focusing exclusively on the extreme event of 23 July 2012 in which a large variety of anisotropies were present at various times during the event.

  2. The anisotropy of multi-TeV cosmic rays

    Science.gov (United States)

    Dingus, Brenda

    2013-02-01

    The arrival directions of cosmic rays will be isotropized by the deflection of these charged particles in the Galactic magnetic fields. For example, a 10 TeV proton in a typical Galactic field of 2 micro Gauss has a gyroradius of only 0.005 parsec (=1000 AU) which is much smaller than the distance to any postulated sources. However, observations of TeV cosmic rays by Milagro, Tibet III, ARGO, and IceCube, show anisotropies on both large and small angular scales. These observations require the detection of large numbers of cosmic rays because the anisotropies are less than a few parts in 1000. The large angular scale anisotropies, such as a dipole, could point to diffusion from a nearby source, but the smaller scale anisotropies of extent ~10 degrees are much more difficult to explain. Possibilities that have been explored in the literature include magnetic funneling of cosmic rays from nearby sources and acceleration by magnetic reconnection in the heliosphere's magnetotail. No matter what the mechanism, these observations provide new information about cosmic ray production, nearby magnetic fields, and how the cosmic rays observed at Earth are affected by their propagation.

  3. FIRE HOSE INSTABILITY DRIVEN BY ALPHA PARTICLE TEMPERATURE ANISOTROPY

    Energy Technology Data Exchange (ETDEWEB)

    Matteini, L.; Schwartz, S. J. [Department of Physics, Imperial College London, London SW7 2AZ (United Kingdom); Hellinger, P. [Astronomical Institute, CAS, Prague (Czech Republic); Landi, S. [Dipartimento di Fisica e Astronomia, Università di Firenze, Firenze (Italy)

    2015-10-10

    We investigate properties of a solar wind-like plasma, including a secondary alpha particle population exhibiting a parallel temperature anisotropy with respect to the background magnetic field, using linear and quasi-linear predictions and by means of one-dimensional hybrid simulations. We show that anisotropic alpha particles can drive a parallel fire hose instability analogous to that generated by protons, but that, remarkably, can also be triggered when the parallel plasma beta of alpha particles is below unity. The wave activity generated by the alpha anisotropy affects the evolution of the more abundant protons, leading to their anisotropic heating. When both ion species have sufficient parallel anisotropies, both of them can drive the instability, and we observe the generation of two distinct peaks in the spectra of the fluctuations, with longer wavelengths associated to alphas and shorter ones to protons. If a non-zero relative drift is present, the unstable modes propagate preferentially in the direction of the drift associated with the unstable species. The generated waves scatter particles and reduce their temperature anisotropy to a marginally stable state, and, moreover, they significantly reduce the relative drift between the two ion populations. The coexistence of modes excited by both species leads to saturation of the plasma in distinct regions of the beta/anisotropy parameter space for protons and alpha particles, in good agreement with in situ solar wind observations. Our results confirm that fire hose instabilities are likely at work in the solar wind and limit the anisotropy of different ion species in the plasma.

  4. Superweak asthenosphere in light of upper mantle seismic anisotropy

    Science.gov (United States)

    Becker, Thorsten W.

    2017-05-01

    Earth's upper mantle includes a ˜200 km thick asthenosphere underneath the plates where viscosity and seismic velocities are reduced compared to the background. This zone of weakness matters for plate dynamics and may be required for the generation of plate tectonics itself. However, recent seismological and electromagnetic studies indicate strong heterogeneity in thinner layers underneath the plates which, if related to more extreme, global viscosity reductions, may require a revision of our understanding of mantle convection. Here, I use dynamically consistent mantle flow modeling and the constraints provided by azimuthal seismic anisotropy as well as plate motions to explore the effect of a range of global and local viscosity reductions. The fit between mantle flow model predictions and observations of seismic anisotropy is highly sensitive to radial and lateral viscosity variations. I show that moderate suboceanic viscosity reductions, to ˜0.01-0.1 times the upper mantle viscosity, are preferred by the fit to anisotropy and global plate motions, depending on layer thickness. Lower viscosities degrade the fit to azimuthal anisotropy. Localized patches of viscosity reduction, or layers of subducted asthenosphere, however, have only limited additional effects on anisotropy or plate velocities. This indicates that it is unlikely that regional observations of subplate anomalies are both continuous and indicative of dramatic viscosity reduction. Locally, such weak patches may exist and would be detectable by regional anisotropy analysis, for example. However, large-scale plate dynamics are most likely governed by broad continent-ocean asthenospheric viscosity contrasts rather than a thin, possibly high melt fraction layer.

  5. Angular dependence of magnetization reversal in epitaxial chromium telluride thin films with perpendicular magnetic anisotropy

    Energy Technology Data Exchange (ETDEWEB)

    Pramanik, Tanmoy, E-mail: pramanik.tanmoy@utexas.edu; Roy, Anupam, E-mail: anupam@austin.utexas.edu; Dey, Rik, E-mail: rikdey@utexas.edu; Rai, Amritesh; Guchhait, Samaresh; Movva, Hema C.P.; Hsieh, Cheng-Chih; Banerjee, Sanjay K.

    2017-09-01

    Highlights: • Perpendicular magnetic anisotropy in epitaxial Cr{sub 2}Te{sub 3} has been investigated. • Presence of a relatively strong second order anisotropy contribution is observed. • Magnetization reversal is explained quantitatively using a 1D defect model. • Relative roles of nucleation and pinning in magnetization reversal are discussed. • Domain structures and switching process are visualized by micromagnetic simulation. - Abstract: We investigate magnetic anisotropy and magnetization reversal mechanism in chromium telluride thin films grown by molecular beam epitaxy. We report existence of strong perpendicular magnetic anisotropy in these thin films, along with a relatively strong second order anisotropy contribution. The angular variation of the switching field observed from the magnetoresistance measurement is explained quantitatively using a one-dimensional defect model. The model reveals the relative roles of nucleation and pinning in the magnetization reversal, depending on the applied field orientation. Micromagnetic simulations are performed to visualize the domain structure and switching process.

  6. Texture and Elastic Anisotropy of Mantle Olivine

    Science.gov (United States)

    Nikitin, A. N.; Ivankina, T. I.; Bourilitchev, D. E.; Klima, K.; Locajicek, T.; Pros, Z.

    Eight olivine rock samples from different European regions were collected for neu- tron texture analyses and for P-wave velocity measurements by means of ultrasonic sounding at various confining pressures. The orientation distribution functions (ODFs) of olivine were determined and pole figures of the main crystallographic planes were calculated. The spatial P-wave velocity distributions were determined at confining pressures from 0.1 to 400 MPa and modelled from the olivine textures. In dependence upon the type of rock (xenolith or dunite) different behavior of both the P-wave veloc- ity distributions and the anisotropy coefficients with various confining pressures was observed. In order to explain the interdependence of elastic anisotropy and hydrostatic pressure, a model for polycrystalline olivine rocks was suggested, which considers the influence of the crystallographic and the mechanical textures on the elastic behaviour of the polycrystal. Since the olivine texture depends upon the active slip systems and the deformation temperature, neutron texture analyses enable us to estimate depth and thermodynamical conditions during texture formation.

  7. Role of Ta-spacer layer on tuning the tilt angle magnetic anisotropy of L1{sub 1}-CoPt/Ta/NiFe exchange springs

    Energy Technology Data Exchange (ETDEWEB)

    Saravanan, P., E-mail: psdrdo@gmail.com [Defence Metallurgical Research Laboratory, Hyderabad 500058 (India); Talapatra, A.; Mohanty, J. [Department of Physics, Indian Institute of Technology Hyderabad, Hyderabad 502285 (India); Hsu, Jen-Hwa, E-mail: jhhsu@phys.ntu.edu.tw [Department of Physics, National Taiwan University, Taipei 106, Taiwan (China); Kamat, S.V. [Defence Metallurgical Research Laboratory, Hyderabad 500058 (India)

    2017-06-15

    Highlights: • Role of Ta-spacer layer in L1{sub 1}-CoPt(10 nm)/Ta//NiFe(4 nm) trilayers was investigated. • Domain size increased at the expense of magnetic phase contrast with increasing t{sub Ta}. • Tilt angle magnetization increased from 43° to 77° upon increasing t{sub Ta} (0–2.5 nm). • Micromagnetic studies confirmed the existence of tilted magnetic anisotropy. • Ta-spacer is effective in preserving competing anisotropies of CoPt and NiFe-layers. - Abstract: L1{sub 1}-CoPt/Ta/NiFe trilayers are chosen as model films for probing the role of spacer layer on tuning the tilt angle magnetization (θ{sub M}) in such exchange springs. For this purpose, a non-magnetic layer (Ta) with varying thickness (t{sub Ta}) from 0 to 2.5 nm was inserted between 10-nm thick CoPt film exhibiting strong perpendicular magnetic anisotropy (PMA) and 4-nm thick NiFe film having in-plane magnetic anisotropy (IMA). With the insertion of Ta-spacer, the magnetic hysteresis loops become more and more tilted as t{sub Ta} increases. Upon increasing the t{sub Ta} from 0 to 2.5 nm, the estimated SQR{sub ⊥} (=M{sub r⊥}/M{sub s⊥}) from the M–H loops is found to decrease moderately; while the θ{sub M} increases significantly from 43° to 77°. MFM images revealed maze-like domain patterns and the domain size tends to increase at the expense of magnetic phase contrast with increasing t{sub Ta}. Micro-magnetic simulation of tilt in the anisotropy axis with respect to the bare CoPt-layer showed a trend similar to that of those observed with the M–H loops obtained by VSM measurements. The results of present study suggest that the insertion of Ta-spacer is not only beneficial in terms of preserving the competing anisotropies such as PMA and IMA of CoPt and NiFe-layers respectively through weakened exchange coupling; but also, act as an appropriate means for realizing tunable tilted magnetic anisotropy in the L1{sub 1}-CoPt/NiFe exchange springs.

  8. Fiscal 1987 R and D of observation system for probing resources. 3/3; 1987 nendo shigen tansayo kansoku system no kenkyu kaihatsu. 3/3

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1988-07-01

    This paper puts together the R and D of a sensor system and a data transmission system in the R and D of observation system for probing resources. In the studies of the on-satellite synthetic-aperture radar (SAR), reexamination was conducted on the basic design of the SAR system and its test plan; also conducted were the drafting of the combination test plan of an SAR/mission transmitter and the design/manufacturing of the machinery required for the test. In the studies of the on-satellite optical sensor, the research of the function/performance of an optical sensor system was carried out, as were the design/manufacturing of an engineering model and the design/model preparation of a visible near infrared radiometer, short-wave infrared radiometer, thermal controller, etc. In the R and D of the data transmission system, a mission recording device was manufactured and tested, with the electrical/mechanical performance confirmed. Further, as a result of the test of the mission transmitter antenna, it was found to fulfill the development specifications. (NEDO)

  9. Fiscal 1987 R and D of observation system for probing resources. 2/3; 1987 nendo shigen tansayo kansoku system no kenkyu kaihatsu. 2/3

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1988-07-01

    This paper puts together the studies of the system design and control technology and of the system design and evaluation technology concerning the R and D of observation system for probing resources. In the studies of the system design and control technology, conducted were the design/examination on the electrical, mechanical and thermal interfaces between the satellite body and a mission transmitter, as well as the examinations on the mounting position, environmental test conditions, etc., with results produced. Also conducted were the interface with the terrestrial station, operation mission analysis, etc. In the studies of the system design and evaluation technology, for the purpose of evaluating ERS-1 optical sensor specifications, experiments by aircraft were carried out which used on-aircraft imaging spectro radiometer, with evaluation performed by means of multi-channel image data so obtained. Further, in the aircraft/space shuttle experiments, examination was carried out on such items as an aircraft system concerning optical sensors, visible near infrared radiometer, short wave infrared radiometer, and on-satellite synthetic-aperture radar. (NEDO)

  10. Cultural probes

    DEFF Research Database (Denmark)

    Madsen, Jacob Østergaard

    The aim of this study was thus to explore cultural probes (Gaver, Boucher et al. 2004), as a possible methodical approach, supporting knowledge production on situated and contextual aspects of occupation.......The aim of this study was thus to explore cultural probes (Gaver, Boucher et al. 2004), as a possible methodical approach, supporting knowledge production on situated and contextual aspects of occupation....

  11. Deep Crustal Anisotropy and its Distortion Through the Seismological Lens

    Science.gov (United States)

    Schulte-Pelkum, V.; Mahan, K. H.

    2011-12-01

    Seismic interpretations of crustal anisotropy often appear to be at odds with expectations based on structural geology. We provide a solution to the apparent discrepancy based on petrological data and synthetic seismograms and present results across the continental US. Seismic investigations of crustal anisotropy offer one of the best chances to observe lower crustal flow in situ, and receiver function (converted wave) studies have good horizontal and depth resolution and are less expensive than active source studies, and suffer from less tradeoff than tomographic studies. A puzzling observation in receiver function studies of the continental crust has been a prevalence of observed plunging axis anisotropy in subhorizontal layers interpreted to have accommodated a significant component of simple shear. In contrast, geological field observations and deformation experiments suggest that shear zones develop a significant boundary-parallel foliation (C-planes in S-C mylonite) after only modest amounts of strain accumulation (~gamma A2), while plunging P anisotropy shows a much higher amplitude single peak and trough (termed A1). Published crustal sample P versus S anisotropies range within a factor of 2 of each other, with the majority of samples showing comparable P and S anisotropy. While the A2 signal theoretically provides a robust detector for anisotropy, we suggest that a search for the larger A1 signal is more likely to be successful. We present seismic forward modeling results for petrological crustal deformation fabrics with aligned mica, amphibole, and quartz for different geometries. We also show results from the EarthScope Transportable Array across areas with presumed past or present lower crustal flow. When observed receiver function signal amplitudes are decomposed into A0 (isotropic, 1-D), A1, and A2 components, the A1 component dominates A2 by a factor of ~3 averaged across the entire network. The A1 component also contains information on isotropic

  12. Characteristics of trapped proton anisotropy at Space Station Freedom altitudes

    Science.gov (United States)

    Armstrong, T. W.; Colborn, B. L.; Watts, J. W.

    1990-01-01

    The ionizing radiation dose for spacecraft in low-Earth orbit (LEO) is produced mainly by protons trapped in the Earth's magnetic field. Current data bases describing this trapped radiation environment assume the protons to have an isotropic angular distribution, although the fluxes are actually highly anisotropic in LEO. The general nature of this directionality is understood theoretically and has been observed by several satellites. The anisotropy of the trapped proton exposure has not been an important practical consideration for most previous LEO missions because the random spacecraft orientation during passage through the radiation belt 'averages out' the anisotropy. Thus, in spite of the actual exposure anisotropy, cumulative radiation effects over many orbits can be predicted as if the environment were isotropic when the spacecraft orientation is variable during exposure. However, Space Station Freedom will be gravity gradient stabilized to reduce drag, and, due to this fixed orientation, the cumulative incident proton flux will remain anisotropic. The anisotropy could potentially influence several aspects of Space Station design and operation, such as the appropriate location for radiation sensitive components and experiments, location of workstations and sleeping quarters, and the design and placement of radiation monitors. Also, on-board mass could possible be utilized to counteract the anisotropy effects and reduce the dose exposure. Until recently only omnidirectional data bases for the trapped proton environment were available. However, a method to predict orbit-average, angular dependent ('vector') trapped proton flux spectra has been developed from the standard omnidirectional trapped proton data bases. This method was used to characterize the trapped proton anisotropy for the Space Station orbit (28.5 degree inclination, circular) in terms of its dependence on altitude, solar cycle modulation (solar minimum vs. solar maximum), shielding thickness

  13. Anisotropy effects in magnetic hyperthermia: A comparison between spherical and cubic exchange-coupled FeO/Fe{sub 3}O{sub 4} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Khurshid, H., E-mail: khurshid@usf.edu, E-mail: sharihar@usf.edu; Nemati, Z.; Phan, M. H.; Mukherjee, P.; Srikanth, H., E-mail: khurshid@usf.edu, E-mail: sharihar@usf.edu [Department of Physics, University of South Florida, Tampa, Florida 33620 (United States); Alonso, J. [Department of Physics, University of South Florida, Tampa, Florida 33620 (United States); BCMaterials Edificio No. 500, Parque Tecnológico de Vizcaya, Derio 48160 (Spain); Fdez-Gubieda, M. L.; Barandiarán, J. M. [BCMaterials Edificio No. 500, Parque Tecnológico de Vizcaya, Derio 48160 (Spain); Depto. Electricidad y Electrónica, Universidad del País Vasco, Leioa 48940 (Spain)

    2015-05-07

    Spherical and cubic exchange-coupled FeO/Fe{sub 3}O{sub 4} nanoparticles, with different FeO:Fe{sub 3}O{sub 4} ratios, have been prepared by a thermal decomposition method to probe anisotropy effects on their heating efficiency. X-ray diffraction and transmission electron microscopy reveal that the nanoparticles are composed of FeO and Fe{sub 3}O{sub 4} phases, with an average size of ∼20 nm. Magnetometry and transverse susceptibility measurements show that the effective anisotropy field is 1.5 times larger for the cubes than for the spheres, while the saturation magnetization is 1.5 times larger for the spheres than for the cubes. Hyperthermia experiments evidence higher values of the specific absorption rate (SAR) for the cubes as compared to the spheres (200 vs. 135 W/g at 600 Oe and 310 kHz). These observations point to an important fact that the saturation magnetization is not a sole factor in determining the SAR and the heating efficiency of the magnetic nanoparticles can be improved by tuning their effective anisotropy.

  14. Seismic anisotropy and mantle flow below subducting slabs

    Science.gov (United States)

    Walpole, Jack; Wookey, James; Kendall, J.-Michael; Masters, T.-Guy

    2017-05-01

    Subduction is integral to mantle convection and plate tectonics, yet the role of the subslab mantle in this process is poorly understood. Some propose that decoupling from the slab permits widespread trench parallel flow in the subslab mantle, although the geodynamical feasibility of this has been questioned. Here, we use the source-side shear wave splitting technique to probe anisotropy beneath subducting slabs, enabling us to test petrofabric models and constrain the geometry of mantle fow. Our global dataset contains 6369 high quality measurements - spanning ∼ 40 , 000 km of subduction zone trenches - over the complete range of available source depths (4 to 687 km) - and a large range of angles in the slab reference frame. We find that anisotropy in the subslab mantle is well characterised by tilted transverse isotropy with a slow-symmetry-axis pointing normal to the plane of the slab. This appears incompatible with purely trench-parallel flow models. On the other hand it is compatible with the idea that the asthenosphere is tilted and entrained during subduction. Trench parallel measurements are most commonly associated with shallow events (source depth slab. This may correspond to the shape preferred orientation of cracks, fractures, and faults opened by slab bending. Meanwhile the deepest events probe the upper lower mantle where splitting is found to be consistent with deformed bridgmanite.

  15. Controlling the anisotropy and domain structure with oblique deposition and substrate rotation

    Science.gov (United States)

    Chowdhury, N.; Bedanta, S.

    2014-02-01

    Effect of substrate rotation on anisotropy and domain structure for a thin ferromagnetic film has been investigated in this work. For this purpose Co films with 10 nm thickness have been prepared by sputtering with oblique angle of incidence for various substrate rotations. This method of preparation induces a uniaxial anisotropy due to shadow deposition effect. The magnetization reversal is studied by magneto-optic Kerr effect (MOKE) based microscope in the longitudinal geometry. The Co films prepared by rotating the substrate with 10 and 20 rpm weakens the anisotropy but does not completely give isotropic films. But this leads to high dispersion in local grain anisotropy resulting in ripple and labyrinth domains. It is observed that the substrate rotation has moderate effect on uniaxial anisotropy but has significant effect on the magnetization reversal process and the domain structure.

  16. On the origin of high transient anisotropies: An exemplification in a Cd-porphyrin

    International Nuclear Information System (INIS)

    Liang, Yu; Klinger, Melanie; Unterreiner, Andreas-Neil; Schalk, Oliver

    2013-01-01

    Transient anisotropy is a widely used spectroscopic method to access the polarization dynamics of a molecular sample. In this contribution, we present results on 5,10,15,20-tetraphenyl-porphyrinato cadmium (II) in tetrahydrofuran which exhibits values exceeding the typical range between 0.4 and −0.2 in dependence of the probe wavelength. These findings are explained by varying contributions from excited state absorption and ground state bleaching/stimulated emission. Model calculations show that time zero values and time decays are complex values that often do not correlate with the underlying physical processes. As a consequence, the interpretation of anisotropy experiments necessitates extreme care

  17. Compressive Acceleration of Solar Energetic Particles within Coronal Mass Ejections: Observations and Theory Relevant to the Solar Probe Plus and Solar Orbiter Missions

    Science.gov (United States)

    Roelof, E. C.

    2015-12-01

    observational technique by which (divV) may be extracted directly from coronograph white-light movies of out-going CMEs, thus offering observational closure of the new theory for SEP acceleration/injection that should be relevant to the Solar Probe Plus and Solar Orbiter missions.

  18. Variable Azimuthal Anisotropy in Earth's Lowermost Mantle

    Science.gov (United States)

    Garnero, Edward J.; Maupin, Valérie; Lay, Thorne; Fouch, Matthew J.

    2004-10-01

    A persistent reversal in the expected polarity of the initiation of vertically polarized shear waves that graze the D'' layer (the layer at the boundary between the outer core and the lower mantle of Earth) in some regions starts at the arrival time of horizontally polarized shear waves. Full waveform modeling of the split shear waves for paths beneath the Caribbean requires azimuthal anisotropy at the base of the mantle. Models with laterally coherent patterns of transverse isotropy with the hexagonal symmetry axis of the mineral phases tilted from the vertical by as much as 20° are consistent with the data. Small-scale convection cells within the mantle above the D'' layer may cause the observed variations by inducing laterally variable crystallographic or shape-preferred orientation in minerals in the D'' layer.

  19. Signatures of Beam - and Anisotropy Driven Oscillitons

    Science.gov (United States)

    Sauer, K.; Dubinin, E.; McKenzie, J. F.

    Oscillitons represent a new class of stationary nonlinear waves, first found in bi-ion plasmas (Sauer et al., 1991) where mode splitting of the `individual' wave modes leads to conditions for phase- and group-standing waves near the `crossing points'. The corresponding structures have signatures of the usual solitons, superimposed by spatial oscillations. Oscillitons may also occur in single-ion plasmas, e.g. in the elec- tron whistler branch. The characteristic features of different types of oscillitons under realistic conditions in space plasmas including damping, beams and anisotropies are analyzed. Relevant mechanisms of coherent waves observed in different frequency ranges (Lion Roars at Earth, ion cyclotron waves near Io and Mars) are discussed.

  20. Magnetic anisotropy of Ni/Cr multilayers

    International Nuclear Information System (INIS)

    Kang, S.; Xia, H.

    1997-01-01

    The magnetic anisotropy of Ni/Cr multilayers has been investigated by using vibrating sample magnetometer (VSM) and ferromagnetic resonance techniques (FMR). The FMR spectra are obtained as a function of the orientation of the applied magnetic field from in-plane to out-of-plane. The results are fitted theoretically to determine the magnetic anisotropy. From VSM and FMR, a positive value for Ni/Cr interface anisotropy is obtained, which favours a perpendicular easy axis. The possible mechanism for the perpendicular anisotropy has been discussed and it may be attributed to the magnetostriction, caused by intrinsic stress due to lattice mismatch. (orig.). With 005 figs., 001 tabs

  1. The Distribution of Chorus and Plasmaspheric Hiss Waves in the Inner Magnetospahere as Functions of Geomagnetic Activity and Solar Wind Parameters as Observed by The Van Allen Probes.

    Science.gov (United States)

    Aryan, H.; Sibeck, D. G.; Balikhin, M. A.; Agapitov, O. V.; Kletzing, C.

    2015-12-01

    The dynamics of the radiation belts is dependent upon the acceleration and loss of radiation belt electrons that is largely determined by the interaction of georesonant wave particles with chorus and plasmaspheric hiss waves. The distribution of these waves in the inner magnetosphere is commonly presented as a function of geomagnetic activity as expressed by the geomagnetic indices (Ae, Kp, and Dst). However, it has been shown that not all geomagnetic storms necessarily increase the flux of energetic electrons at the radiation belts. In fact, almost 20% of all geomagnetic storms cause a decrease in the flux of energetic electrons, while 30% has relatively no effect. Also, the geomagnetic indices are indirect, nonspecific parameters compiled from imperfectly covered ground based measurements that lack time history. This emphasises the need to present wave distributions as a function of both geomagnetic activity and solar wind parameters, such as velocity (V), density (n), and interplanetary magnetic field component (Bz), that are known to be predominantly effective in the control of radiation belt energetic electron fluxes. This study presents the distribution of chorus and plasmaspheric hiss waves in the inner magnetosphere as functions of both geomagnetic activity and solar wind parameters for different L-shell, magnetic local time, and magnetic latitude. This study uses almost three years of data measured by the EMFISIS on board the Van Allen Probes. Initial results indicate that the intensity of chorus and plasmaspheric hiss emissions are not only dependent on the geomagnetic activity but also dependent on solar wind parameters. The largest average wave intensities are observed with equatorial chorus in the region 4

  2. Seismological Evidence for General Anisotropy in the d" Layer Beneath the Caribbean

    Science.gov (United States)

    Garnero, E. J.; Maupin, V.; Lay, T.; Fouch, M. J.

    2004-12-01

    Current models of anisotropy in D" are based on time delays observed between the SH and the SV components of core-reflected or core-grazing phases, which can be explained by the simplest form for anisotropy, vertical transverse isotropy (VTI). In a detailed analysis of high-quality broadband S (or Sdiff) phases, we find that many recordings do not show such simple delays; rather, some coupling between the SH and SV components is apparent: SV components have a small initial pulse with the polarity opposite to that predicted by isotropic or VTI structures. We analyze deep South American events recorded by the Canadian National Seismic Network, sampling D" under the Caribbean Ocean and Central America. The data are corrected for upper mantle anisotropy and compared to full wave theory synthetic seismograms calculated from isotropic, transversely isotropic, and azimuthally anisotropic structures. While restrictions in azimuthal sampling of this region limit a complete characterization of D" anisotropy, the need for azimuthal anisotropy is robustly established. A simple form of azimuthal anisotropy is explored which entails tilting the symmetry axis of transverse isotropy away from the vertical (TTI). Anomalous data are reproduced by a 20 degree tilt, and discriminate between eastward and westward tilting orientations, as well as zero tilts (i.e., isotropy or VTI). However, we note this does not preclude other forms of azimuthal anisotropy. Out of the 80 highest quality records analyzed, 22 are uniquely explained by the eastward TTI structures (with 34 records compatible with such a structure); 16 are compatible with westward TTI, with 2 uniquely requiring such a tilt. This gives strong evidence for lateral heterogeneity in azimuthal anisotropy at a lateral scale of a several 100 km. Further interpretation of the results requires identification the physical mechanism behind seismic anisotropy in D". Together with the recent discovery of the possibly anisotropic post

  3. Probability density functions for radial anisotropy: implications for the upper 1200 km of the mantle

    Science.gov (United States)

    Beghein, Caroline; Trampert, Jeannot

    2004-01-01

    The presence of radial anisotropy in the upper mantle, transition zone and top of the lower mantle is investigated by applying a model space search technique to Rayleigh and Love wave phase velocity models. Probability density functions are obtained independently for S-wave anisotropy, P-wave anisotropy, intermediate parameter η, Vp, Vs and density anomalies. The likelihoods for P-wave and S-wave anisotropy beneath continents cannot be explained by a dry olivine-rich upper mantle at depths larger than 220 km. Indeed, while shear-wave anisotropy tends to disappear below 220 km depth in continental areas, P-wave anisotropy is still present but its sign changes compared to the uppermost mantle. This could be due to an increase with depth of the amount of pyroxene relative to olivine in these regions, although the presence of water, partial melt or a change in the deformation mechanism cannot be ruled out as yet. A similar observation is made for old oceans, but not for young ones where VSH> VSV appears likely down to 670 km depth and VPH> VPV down to 400 km depth. The change of sign in P-wave anisotropy seems to be qualitatively correlated with the presence of the Lehmann discontinuity, generally observed beneath continents and some oceans but not beneath ridges. Parameter η shows a similar age-related depth pattern as shear-wave anisotropy in the uppermost mantle and it undergoes the same change of sign as P-wave anisotropy at 220 km depth. The ratio between dln Vs and dln Vp suggests that a chemical component is needed to explain the anomalies in most places at depths greater than 220 km. More tests are needed to infer the robustness of the results for density, but they do not affect the results for anisotropy.

  4. Mobile probes

    DEFF Research Database (Denmark)

    Ørngreen, Rikke; Jørgensen, Anna Neustrup; Noesgaard, Signe Schack

    2016-01-01

    to in an interview. This method provided valuable insight into the contextual use, i.e. how did the online resource transfer to the work practice. However, the research team also found that mobile probes may provide the scaffolding necessary for individual and peer learning at a very local (intra-school) community...... level. This paper is an initial investigation of how the mobile probes process proved to engage teachers in their efforts to improve teaching. It also highlights some of the barriers emerging when applying mobile probes as a scaffold for learning.......A project investigating the effectiveness of a collection of online resources for teachers' professional development used mobile probes as a data collection method. Teachers received questions and tasks on their mobile in a dialogic manner while in their everyday context as opposed...

  5. Cross Comparison of Electron Density and Electron Temperature Observations from the DICE CubeSat Langmuir Probes and the Millstone Hill Incoherent Scatter Radar.

    Science.gov (United States)

    Swenson, C.; Erickson, P. J.; Crowley, G.; Pilinski, M.; Barjatya, A.; Fish, C. S.

    2014-12-01

    The Dynamic Ionosphere CubeSat Experiment (DICE) consists of two identical 1.5U CubeSats deployed simultaneously from a single P-POD (Poly Picosatellite Orbital Deployer) into the same orbit. Several observational campaigns were planned between the DICE CubeSats and the mid-latitude Millstone Hill Incoherent Scatter Radar (ISR) in order to calibrate the DICE measurements of electron density and electron temperature. In this presentation, we compare in-situ observations from the Dynamic Ionosphere CubeSat Experiment (DICE) and from the Millstone Hill ISR. Both measurements are cross-calibrated against an assimilative model of the global ionospheric electron density. The electron density and electron temperature were obtained for three Millstone Hill DICE overflights (2013-03-12, 2013-03-15, 2013-03-17). We compare the data during quiet and geomagnetically disturbed conditions and find evidence of an storm enhanced density (SED) plume in the topside ionosphere on 2013-03-17 at 19? UTC. During this disturbed interval, American longitude sector high density plasma was convected near 15 SLT towards the noontime cusp. DICE was selected for flight under the NSF "CubeSat-based Science Mission for Space Weather and Atmospheric Research" program. The DICE twin satellites were launched on a Delta II rocket on October 28, 2011. The satellites are flying in a "leader-follower" formation in an elliptical orbit which ranges from 820 to 400 km in altitude. Each satellite carries a fixed-bias DC Langmuir Probe (DCP) to measure in-situ ionospheric plasma densities and a science grade magnetometer to measure DC and AC geomagnetic fields. The purpose of these measurements was to permit accurate identification of storm-time features such as the SED bulge and plume. The mission team combines expertise from ASTRA, Utah State University/Space Dynamics Laboratory (USU/SDL), and Embry-Riddle Aeronautical University. In this paper we present a comparison of data from DICE and Millstone Hill

  6. Anisotropy in Dynamical Models of Elliptical Galaxy Dark Halos

    Science.gov (United States)

    Forestell, Amy; Gebhardt, K.

    2013-07-01

    Abstract (2,250 Maximum Characters): We discuss the orbital anisotropy results of axisymmetric orbit-superposition dynamical models of elliptical galaxies NGC 821 and NGC 4697. For NGC 821 stellar kinematics are used to determine the best-fitted dark halo (Forestell 2010), then we determine the orbital properties required for planetary nebulae to match the observed kinematic data (Romanowsky et al. 2003) in that assumed dark halo. For NGC 4697 we use both stellar and planetary nebula kinematics (Pinkney et al. 2003, Mendez et al. 2009) to model the galaxy dark halo. In both galaxies we find that the planetary nebulae, which are located at large radii, show radial anisotropy. This is consistent with the results of Dekel et al. (2005), who use disk galaxy merger simulations to show that large anisotropies can be created in the resulting elliptical galaxies and that this anisotropy in combination with the different density profile of a young population could explain how the low dispersions from planetary nebulae measurements are also consistent with typical dark matter halos.

  7. Anisotropy signature in reverse-time migration extended images

    KAUST Repository

    Sava, Paul C.

    2014-11-04

    Reverse-time migration can accurately image complex geologic structures in anisotropic media. Extended images at selected locations in the Earth, i.e., at common-image-point gathers, carry rich information to characterize the angle-dependent illumination and to provide measurements for migration velocity analysis. However, characterizing the anisotropy influence on such extended images is a challenge. Extended common-image-point gathers are cheap to evaluate since they sample the image at sparse locations indicated by the presence of strong reflectors. Such gathers are also sensitive to velocity error that manifests itself through moveout as a function of space and time lags. Furthermore, inaccurate anisotropy leaves a distinctive signature in common-image-point gathers, which can be used to evaluate anisotropy through techniques similar to the ones used in conventional wavefield tomography. It specifically admits a V-shaped residual moveout with the slope of the "V" flanks depending on the anisotropic parameter η regardless of the complexity of the velocity model. It reflects the fourth-order nature of the anisotropy influence on moveout as it manifests itself in this distinct signature in extended images after handling the velocity properly in the imaging process. Synthetic and real data observations support this assertion.

  8. New method for estimating clustering of DNA lesions induced by physical/chemical mutagens using fluorescence anisotropy.

    Science.gov (United States)

    Akamatsu, Ken; Shikazono, Naoya; Saito, Takeshi

    2017-11-01

    We have developed a new method for estimating the localization of DNA damage such as apurinic/apyrimidinic sites (APs) on DNA using fluorescence anisotropy. This method is aimed at characterizing clustered DNA damage produced by DNA-damaging agents such as ionizing radiation and genotoxic chemicals. A fluorescent probe with an aminooxy group (AlexaFluor488) was used to label APs. We prepared a pUC19 plasmid with APs by heating under acidic conditions as a model for damaged DNA, and subsequently labeled the APs. We found that the observed fluorescence anisotropy (r obs ) decreases as averaged AP density (λ AP : number of APs per base pair) increases due to homo-FRET, and that the APs were randomly distributed. We applied this method to three DNA-damaging agents, 60 Co γ-rays, methyl methanesulfonate (MMS), and neocarzinostatin (NCS). We found that r obs -λ AP relationships differed significantly between MMS and NCS. At low AP density (λ AP  < 0.001), the APs induced by MMS seemed to not be closely distributed, whereas those induced by NCS were remarkably clustered. In contrast, the AP clustering induced by 60 Co γ-rays was similar to, but potentially more likely to occur than, random distribution. This simple method can be used to estimate mutagenicity of ionizing radiation and genotoxic chemicals. Copyright © 2017 Elsevier Inc. All rights reserved.

  9. Stomatal Opening: The Role of Cell-Wall Mechanical Anisotropy and Its Analytical Relations to the Bio-composite Characteristics

    Directory of Open Access Journals (Sweden)

    Ziv Marom

    2017-12-01

    Full Text Available Stomata are pores on the leaf surface, which are formed by a pair of curved, tubular guard cells; an increase in turgor pressure deforms the guard cells, resulting in the opening of the stomata. Recent studies employed numerical simulations, based on experimental data, to analyze the effects of various structural, chemical, and mechanical features of the guard cells on the stomatal opening characteristics; these studies all support the well-known qualitative observation that the mechanical anisotropy of the guard cells plays a critical role in stomatal opening. Here, we propose a computationally based analytical model that quantitatively establishes the relations between the degree of anisotropy of the guard cell, the bio-composite constituents of the cell wall, and the aperture and area of stomatal opening. The model introduces two non-dimensional key parameters that dominate the guard cell deformations—the inflation driving force and the anisotropy ratio—and it serves as a generic framework that is not limited to specific plant species. The modeling predictions are in line with a wide range of previous experimental studies, and its analytical formulation sheds new light on the relations between the structure, mechanics, and function of stomata. Moreover, the model provides an analytical tool to back-calculate the elastic characteristics of the matrix that composes the guard cell walls, which, to the best of our knowledge, cannot be probed by direct nano-mechanical experiments; indeed, the estimations of our model are in good agreement with recently published results of independent numerical optimization schemes. The emerging insights from the stomatal structure-mechanics “design guidelines” may promote the development of miniature, yet complex, multiscale composite actuation mechanisms for future engineering platforms.

  10. Loss of long-range magnetic order in a nanoparticle assembly due to random anisotropy

    International Nuclear Information System (INIS)

    Binns, C; Howes, P B; Baker, S H; Marchetto, H; Potenza, A; Steadman, P; Dhesi, S S; Roy, M; Everard, M J; Rushforth, A

    2008-01-01

    We have used soft x-ray photoemission electron microscopy (XPEEM) combined with x-ray magnetic circular dichroism (XMCD) and DC SQUID (superconducting quantum interference device) magnetometry to probe the magnetic ground state in Fe thin films produced by depositing size-selected gas-phase Fe nanoparticles with a diameter of 1.7 nm (∼200 atoms) onto Si substrates. The depositions were carried out in ultrahigh vacuum conditions and thicknesses of the deposited film in the range 5-50 nm were studied. The magnetometry data are consistent with the film forming a correlated super-spin glass with a magnetic correlation length ∼5 nm. The XPEEM magnetic maps from the cluster-assembled films were compared to those for a conventional thin Fe film with a thickness of 20 nm produced by a molecular beam epitaxy (MBE) source. Whereas a normal magnetic domain structure is observed in the conventional MBE thin film, no domain structure could be observed in any of the nanoparticle films down to the resolution limit of the XMCD based XPEEM (100 nm) confirming the ground state indicated by the magnetometry measurements. This observation is consistent with the theoretical prediction that an arbitrarily weak random anisotropy field will destroy long-range magnetic order

  11. Seismic anisotropies of the Songshugou peridotites (Qinling orogen, central China) and their seismic implications

    Science.gov (United States)

    Cao, Yi; Jung, Haemyeong; Song, Shuguang

    2018-01-01

    Though extensively studied, the roles of olivine crystal preferred orientations (CPOs or fabrics) in affecting the seismic anisotropies in the Earth's upper mantle are rather complicated and still not fully known. In this study, we attempted to address this issue by analyzing the seismic anisotropies [e.g., P-wave anisotropy (AVp), S-wave polarization anisotropy (AVs), radial anisotropy (ξ), and Rayleigh wave anisotropy (G)] of the Songshugou peridotites (dunite dominated) in the Qinling orogen in central China, based on our previously reported olivine CPOs. The seismic anisotropy patterns of olivine aggregates in our studied samples are well consistent with the prediction for their olivine CPO types; and the magnitude of seismic anisotropies shows a striking positive correlation with equilibrium pressure and temperature (P-T) conditions. Significant reductions of seismic anisotropies (AVp, max. AVs, and G) are observed in porphyroclastic dunite compared to coarse- and fine-grained dunites, as the results of olivine CPO transition (from A-/D-type in coarse-grained dunite, through AG-type-like in porphyroclastic dunite, to B-type-like in fine-grained dunite) and strength variation (weakening: A-/D-type → AG-type-like; strengthening: AG-type-like → B-type-like) during dynamic recrystallization. The transition of olivine CPOs from A-/D-type to B-/AG-type-like in the forearc mantle may weaken the seismic anisotropies and deviate the fast velocity direction and the fast S-wave polarization direction from trench-perpendicular to trench-oblique direction with the cooling and aging of forearc mantle. Depending on the size and distribution of the peridotite body such as the Songshugou peridotites, B- and AG-type-like olivine CPOs can be an additional (despite minor) local contributor to the orogen-parallel fast velocity direction and fast shear-wave polarization direction in the orogenic crust such as in the Songshugou area in Qinling orogen.

  12. The signal of mantle anisotropy in the coupling of normal modes

    Science.gov (United States)

    Beghein, Caroline; Resovsky, Joseph; van der Hilst, Robert D.

    2008-12-01

    We investigate whether the coupling of normal mode (NM) multiplets can help us constrain mantle anisotropy. We first derive explicit expressions of the generalized structure coefficients of coupled modes in terms of elastic coefficients, including the Love parameters describing radial anisotropy and the parameters describing azimuthal anisotropy (Jc, Js, Kc, Ks, Mc, Ms, Bc, Bs, Gc, Gs, Ec, Es, Hc, Hs, Dc and Ds). We detail the selection rules that describe which modes can couple together and which elastic parameters govern their coupling. We then focus on modes of type 0Sl - 0Tl+1 and determine whether they can be used to constrain mantle anisotropy. We show that they are sensitive to six elastic parameters describing azimuthal anisotropy, in addition to the two shear-wave elastic parameters L and N (i.e. VSV and VSH). We find that neither isotropic nor radially anisotropic mantle models can fully explain the observed degree two signal. We show that the NM signal that remains after correction for the effect of the crust and mantle radial anisotropy can be explained by the presence of azimuthal anisotropy in the upper mantle. Although the data favour locating azimuthal anisotropy below 400km, its depth extent and distribution is still not well constrained by the data. Consideration of NM coupling can thus help constrain azimuthal anisotropy in the mantle, but joint analyses with surface-wave phase velocities is needed to reduce the parameter trade-offs and improve our constraints on the individual elastic parameters and the depth location of the azimuthal anisotropy.

  13. Response of Velocity Anisotropy of Shale Under Isotropic and Anisotropic Stress Fields

    Science.gov (United States)

    Li, Xiaying; Lei, Xinglin; Li, Qi

    2018-03-01

    We investigated the responses of P-wave velocity and associated anisotropy in terms of Thomsen's parameters to isotropic and anisotropic stress fields on Longmaxi shales cored along different directions. An array of piezoelectric ceramic transducers allows us to measure P-wave velocities along numerous different propagation directions. Anisotropic parameters, including the P-wave velocity α along a symmetry axis, Thomsen's parameters ɛ and δ, and the orientation of the symmetry axis, could then be extracted by fitting Thomsen's weak anisotropy model to the experimental data. The results indicate that Longmaxi shale displays weakly intrinsic velocity anisotropy with Thomsen's parameters ɛ and δ being approximately 0.05 and 0.15, respectively. The isotropic stress field has only a slight effect on velocity and associated anisotropy in terms of Thomsen's parameters. In contrast, both the magnitude and orientation of the anisotropic stress field with respect to the shale fabric are important in controlling the evolution of velocity and associated anisotropy in a changing stress field. For shale with bedding-parallel loading, velocity anisotropy is enhanced because velocities with smaller angles relative to the maximum stress increase significantly during the entire loading process, whereas those with larger angles increase slightly before the yield stress and afterwards decrease with the increasing differential stress. For shale with bedding-normal loading, anisotropy reversal is observed, and the anisotropy is progressively modified by the applied differential stress. Before reaching the yield stress, velocities with smaller angles relative to the maximum stress increase more significantly and even exceed the level of those with larger angles. After reaching the yield stress, velocities with larger angles decrease more significantly. Microstructural features such as the closure and generation of microcracks can explain the modification of the velocity anisotropy

  14. Particle physics implications of Wilkinson microwave anisotropy ...

    Indian Academy of Sciences (India)

    ... Journals; Pramana – Journal of Physics; Volume 63; Issue 6. Particle physics implications of Wilkinson microwave anisotropy project measurements. U A Yajnik. Volume 63 Issue 6 December 2004 pp 1317-1330 ... Keywords. Cosmic microwave background radiation; inflation; Wilkinson microwave anisotropy project.

  15. An investigation of Oxygen adsorption on W(110) using reflectance anisotropy spectroscopy

    International Nuclear Information System (INIS)

    Zeybek, O.

    2004-01-01

    The probe of metal surface electronic structure and results of the oxidation of a BCC material and the first Joint Density of States interpretation of the spectrum from same metal have been presented. The surface sensitivity of RAS has been exploited when applied to a cubic single crystal to study the surface electronic structure of W(110) and the resulting chemisorption-induced changes upon exposure to oxygen. Oxidation of the surface is monitored until a final exposure of 10 Langmuirs is reached. A decrease of reflectance anisotropy signal is obtained with increasing oxygen coverage on the substrate and a coverage of ∼0.75 ML results in zero anisotropy over the reflectance anisotropy energy range

  16. Electron anisotropy: A tool to discriminate dark matter in cosmic rays

    International Nuclear Information System (INIS)

    Borriello, Enrico; Maccione, Luca; Cuoco, Alessandro

    2012-01-01

    Indirect searches of particle Dark Matter (DM) with high energy Cosmic Rays (CR) are typically affected by large uncertainties. We show that, on the contrary, the DM intrinsic degree of anisotropy in the arrival directions of high energy CR electrons and positrons (CRE) is basically model independent and offers a straightforward criterion to discriminate among CRE from DM or from local discrete sources, like e.g. pulsars. In particular, in absence of the latter, DM sets the maximum degree of total anisotropy. As a consequence, if a larger anisotropy is detected, this would constitute an unambiguous evidence for the presence of astrophysical local discrete CRE sources. The Fermi-LAT will be able to probe such scenarios in the next years.

  17. Probing Protein Multidimensional Conformational Fluctuations by Single-Molecule Multiparameter Photon Stamping Spectroscopy

    Science.gov (United States)

    2015-01-01

    Conformational motions of proteins are highly dynamic and intrinsically complex. To capture the temporal and spatial complexity of conformational motions and further to understand their roles in protein functions, an attempt is made to probe multidimensional conformational dynamics of proteins besides the typical one-dimensional FRET coordinate or the projected conformational motions on the one-dimensional FRET coordinate. T4 lysozyme hinge-bending motions between two domains along α-helix have been probed by single-molecule FRET. Nevertheless, the domain motions of T4 lysozyme are rather complex involving multiple coupled nuclear coordinates and most likely contain motions besides hinge-bending. It is highly likely that the multiple dimensional protein conformational motions beyond the typical enzymatic hinged-bending motions have profound impact on overall enzymatic functions. In this report, we have developed a single-molecule multiparameter photon stamping spectroscopy integrating fluorescence anisotropy, FRET, and fluorescence lifetime. This spectroscopic approach enables simultaneous observations of both FRET-related site-to-site conformational dynamics and molecular rotational (or orientational) motions of individual Cy3-Cy5 labeled T4 lysozyme molecules. We have further observed wide-distributed rotational flexibility along orientation coordinates by recording fluorescence anisotropy and simultaneously identified multiple intermediate conformational states along FRET coordinate by monitoring time-dependent donor lifetime, presenting a whole picture of multidimensional conformational dynamics in the process of T4 lysozyme open-close hinge-bending enzymatic turnover motions under enzymatic reaction conditions. By analyzing the autocorrelation functions of both lifetime and anisotropy trajectories, we have also observed the dynamic and static inhomogeneity of T4 lysozyme multidimensional conformational fluctuation dynamics, providing a fundamental

  18. Distinguishing between stress-induced and structural anisotropy at Mount Ruapehu volcano, New Zealand

    Science.gov (United States)

    Johnson, Jessica H.; Savage, Martha K.; Townend, John

    2011-12-01

    We have created a benchmark of spatial variations in shear wave anisotropy around Mount Ruapehu, New Zealand, against which to measure future temporal changes. Anisotropy in the crust is often assumed to be caused by stress-aligned microcracks, and the polarization of the fast quasi-shear wave (ϕ) is thus interpreted to indicate the direction of maximum horizontal stress, but can also be due to aligned minerals or macroscopic fractures. Changes in seismic anisotropy have been observed following a major eruption in 1995/96 and were attributed to changes in stress from the depressurization of the magmatic system. Three-component broadband seismometers have been deployed to complement the permanent stations that surround Ruapehu, creating a combined network of 34 three-component seismometers. This denser observational network improves the resolution with which spatial variations in seismic anisotropy can be examined. Using an automated shear wave splitting analysis, we examine local earthquakes in 2008. We observe a strong azimuthal dependence of ϕ and so introduce a spatial averaging technique and two-dimensional tomography of recorded delay times. The anisotropy can be divided into regions in which ϕ agrees with stress estimations from focal mechanism inversions, suggesting stress-induced anisotropy, and those in which ϕ is aligned with structural features such as faults, suggesting structural anisotropy. The pattern of anisotropy that is inferred to be stress related cannot be modeled adequately using Coulomb modeling with a dike-like inflation source. We suggest that the stress-induced anisotropy is affected by loading of the volcano and a lithospheric discontinuity.

  19. Distinguishing between stress-induced and structural anisotropy at Mount Ruapehu volcano, New Zealand

    Science.gov (United States)

    Johnson, J. H.; Savage, M.K.; Townend, J.

    2011-01-01

    We have created a benchmark of spatial variations in shear wave anisotropy around Mount Ruapehu, New Zealand, against which to measure future temporal changes. Anisotropy in the crust is often assumed to be caused by stress-aligned microcracks, and the polarization of the fast quasi-shear wave (??) is thus interpreted to indicate the direction of maximum horizontal stress, but can also be due to aligned minerals or macroscopic fractures. Changes in seismic anisotropy have been observed following a major eruption in 1995/96 and were attributed to changes in stress from the depressurization of the magmatic system. Three-component broadband seismometers have been deployed to complement the permanent stations that surround Ruapehu, creating a combined network of 34 three-component seismometers. This denser observational network improves the resolution with which spatial variations in seismic anisotropy can be examined. Using an automated shear wave splitting analysis, we examine local earthquakes in 2008. We observe a strong azimuthal dependence of ?? and so introduce a spatial averaging technique and two-dimensional tomography of recorded delay times. The anisotropy can be divided into regions in which ?? agrees with stress estimations from focal mechanism inversions, suggesting stress-induced anisotropy, and those in which ?? is aligned with structural features such as faults, suggesting structural anisotropy. The pattern of anisotropy that is inferred to be stress related cannot be modeled adequately using Coulomb modeling with a dike-like inflation source. We suggest that the stress-induced anisotropy is affected by loading of the volcano and a lithospheric discontinuity. Copyright 2011 by the American Geophysical Union.

  20. DNA probes

    International Nuclear Information System (INIS)

    Castelino, J.

    1992-01-01

    The creation of DNA probes for detection of specific nucleotide segments differs from ligand detection in that it is a chemical rather than an immunological reaction. Complementary DNA or RNA is used in place of the antibody and is labelled with 32 P. So far, DNA probes have been successfully employed in the diagnosis of inherited disorders, infectious diseases, and for identification of human oncogenes. The latest approach to the diagnosis of communicable and parasitic infections is based on the use of deoxyribonucleic acid (DNA) probes. The genetic information of all cells is encoded by DNA and DNA probe approach to identification of pathogens is unique because the focus of the method is the nucleic acid content of the organism rather than the products that the nucleic acid encodes. Since every properly classified species has some unique nucleotide sequences that distinguish it from every other species, each organism's genetic composition is in essence a finger print that can be used for its identification. In addition to this specificity, DNA probes offer other advantages in that pathogens may be identified directly in clinical specimens

  1. RADIOACTIVE UHECR ASTRONOMY: CORRELATING GAMMA ANISOTROPY AND NEUTRINO PEV EVENTS

    Directory of Open Access Journals (Sweden)

    Daniele Fargion

    2013-12-01

    Full Text Available UHECR (Ultra High Energy Cosmic Rays were expected to be protons, to fly straight and to suffer of a GZK (opacity on CMB radiation cut off. AUGER did suggest on 2007 that such early UHECR anisotropy was compatible with the foreseen Super-Galactic plane while both HIRES and AUGER confirmed such apparent GZK cut-off in the spectra. However the same AUGER composition since 2007 was favoring nuclei (and not nucleon. The recent absence of narrow angle clustering in UHECR maps, as it should be expected by protons, the missing of events along nearest Cluster Virgo, the wide spread (16° angle of UHECR along CenA are in disagreement with first proton–UHECR AUGER understanding. We claimed since 2008 a light nuclei role for CenA crowded area. On the other side the ICECUBE absence of TeVs neutrino clustering or anisotropy, its spectra steepening is favoring mostly a ruling atmospheric neutrino noise up to tens TeV. However recent two PeV neutrino event cannot easily coexist or being extrapolate with such atmospheric ruling scenario, nor with GZK (either nucleon or nuclei secondaries expected spectra. Finally tens TeV gamma anisotropy in ARGO–MILAGRO–ICECUBE maps may hardly be associated with known hadronic sources. Weimagine such anisotropy ruled by diffused gamma secondaries, being shine along UHECR bending and flight: radioactive light and heavy UHECR nuclei, while decaying in flight, may paint in the sky (by gamma, electrons and neutrinos their trajectories and bending, connecting UHECR spread events with TeV anisotropy, as well offering a very realistic source of first, otherwise puzzling, observed PeV neutrinos.

  2. Fluorescence anisotropy of diphenylhexatriene and its cationic Trimethylamino derivative in liquid dipalmitoylphosphatidylcholine liposomes: opposing responses to isoflurane

    Directory of Open Access Journals (Sweden)

    Nelson Steven C

    2012-03-01

    Full Text Available Abstract Background The mechanism of action of volatile general anesthetics has not yet been resolved. In order to identify the effects of isoflurane on the membrane, we measured the steady-state anisotropy of two fluorescent probes that reside at different depths. Incorporation of anesthetic was confirmed by shifting of the main phase transition temperature. Results In liquid crystalline dipalmitoylphosphatidylcholine liposomes, isoflurane (7-25 mM in the bath increases trimethylammonium-diphenylhexatriene fluorescence anisotropy by ~0.02 units and decreases diphenylhexatriene anisotropy by the same amount. Conclusions The anisotropy data suggest that isoflurane decreases non-axial dye mobility in the headgroup region, while increasing it in the tail region. We propose that these results reflect changes in the lateral pressure profile of the membrane.

  3. Quantitative assessment of submicron scale anisotropy in tissue multifractality by scattering Mueller matrix in the framework of Born approximation

    Science.gov (United States)

    Das, Nandan Kumar; Dey, Rajib; Chakraborty, Semanti; Panigrahi, Prasanta K.; Meglinski, Igor; Ghosh, Nirmalya

    2018-04-01

    A number of tissue-like disordered media exhibit local anisotropy of scattering in the scaling behavior. Scaling behavior contains wealth of fractal or multifractal properties. We demonstrate that the spatial dielectric fluctuations in a sample of biological tissue exhibit multifractal anisotropy. Multifractal anisotropy encoded in the wavelength variation of the light scattering Mueller matrix and manifesting as an intriguing spectral diattenuation effect. We developed an inverse method for the quantitative assessment of the multifractal anisotropy. The method is based on the processing of relevant Mueller matrix elements in Fourier domain by using Born approximation, followed by the multifractal analysis. The approach promises for probing subtle micro-structural changes in biological tissues associated with the cancer and precancer, as well as for non-destructive characterization of a wide range of scattering materials.

  4. Conductivity Probe

    Science.gov (United States)

    2008-01-01

    The Thermal and Electrical Conductivity Probe (TECP) for NASA's Phoenix Mars Lander took measurements in Martian soil and in the air. The needles on the end of the instrument were inserted into the Martian soil, allowing TECP to measure the propagation of both thermal and electrical energy. TECP also measured the humidity in the surrounding air. The needles on the probe are 15 millimeters (0.6 inch) long. The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  5. Remarks to solve disagreement between Gravity anisotropy and constraints on the variation of Gravitational constant (big G) based on gravimetric data Reply to "Nano-constraints on the spatial anisotropy of the Gravitational Constant"

    CERN Document Server

    Gershteyn, M L; Gershteyn, A; Karagioz, O V

    2002-01-01

    Remarks to solve disagreement between Gravity anisotropy observed at decimeter distances and constraints on the spatial variation of Gravitational constant (big G) based on gravimetric data and Lunar Laser Ranging (LLR) experiments. Disagreement disappears when we assume that Gravitational anisotropy may depend on the magnitudes of the interacting masses and the distance between them.

  6. A search for small-scale anisotropy of PeV cosmic rays

    Science.gov (United States)

    Zotov, M. Yu.; Kulikov, G. V.

    2012-11-01

    Recent results of Milagro, Tibet, ARGO-YBJ, and IceCube experiments on the small-scale anisotropy of Galactic cosmic rays (CRs) with energies from units up to a few hundred TeV arise a question on a possible nature of the observed phenomenon, as well as on the anisotropy of CRs at higher energies. An analysis of a small-scale anisotropy of CRs with energies at around PeV registered with the EAS MSU array presented in the article, reveals a number of regions with an excessive flux. A typical size of the regions varies from 3° up to 12°. We study correlation of these regions with positions of potential astrophysical sources of CRs and discuss a possible origin of the observed anisotropy.

  7. Dynamical vs. geometric anisotropy in relativistic heavy-ion collisions. Which one prevails?

    Energy Technology Data Exchange (ETDEWEB)

    Bravina, L.V. [University of Oslo, Department of Physics, Oslo (Norway); National Research Nuclear University ' ' MEPhI' ' (Moscow Engineering Physics Institute), Moscow (Russian Federation); Lokhtin, I.P.; Malinina, L.V.; Petrushanko, S.V.; Snigirev, A.M. [Lomonosov Moscow State University, Skobeltsyn Institute of Nuclear Physics, Moscow (Russian Federation); Zabrodin, E.E. [Lomonosov Moscow State University, Skobeltsyn Institute of Nuclear Physics, Moscow (Russian Federation); University of Oslo, Department of Physics, Oslo (Norway); National Research Nuclear University ' ' MEPhI' ' (Moscow Engineering Physics Institute), Moscow (Russian Federation)

    2017-11-15

    We study the influence of geometric and dynamical anisotropies on the development of flow harmonics and, simultaneously, on the second- and third-order oscillations of femtoscopy radii. The analysis is done within the Monte Carlo event generator HYDJET++, which was extended to dynamical triangular deformations. It is shown that the merely geometric anisotropy provides the results which anticorrelate with the experimental observations of either v{sub 2} (or v{sub 3}) or second-order (or third-order) oscillations of the femtoscopy radii. Decays of resonances significantly increase the emitting areas but do not change the phases of the radii oscillations. In contrast to the spatial deformations, the dynamical anisotropy alone provides the correct qualitative description of the flow and the femtoscopy observables simultaneously. However, one needs both types of the anisotropy to match quantitatively the experimental data. (orig.)

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

    Science.gov (United States)

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

    2018-04-01

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

  9. Pollution Probe.

    Science.gov (United States)

    Chant, Donald A.

    This book is written as a statement of concern about pollution by members of Pollution Probe, a citizens' anti-pollution group in Canada. Its purpose is to create public awareness and pressure for the eventual solution to pollution problems. The need for effective government policies to control the population explosion, conserve natural resources,…

  10. Probe specificity

    International Nuclear Information System (INIS)

    Laget, J.M.

    1986-11-01

    Specificity and complementarity of hadron and electron probes must be systematically developed to answer three questions currently asked in intermediate energy nuclear physics: what is nucleus structure at short distances, what is nature of short range correlations, what is three body force nature [fr

  11. Substrate temperature effect on the structural anisotropy in amorphous Tb-Fe films

    Science.gov (United States)

    Harris, V. G.; Hellman, F.; Elam, W. T.; Koon, N. C.

    1993-05-01

    Using extended x-ray absorption fine structures (EXAFS) measurements we have investigated the atomic environment around the Fe atom in a series of amorphous Tb0.26Fe0.74 films having different magnetic anisotropy energies owing to different deposition temperatures. The polarization properties of synchrotron radiation allowed the separate study of structure parallel and perpendicular to the sample plane. An anisotropy between these two structures was observed. Modeling results indicate this anisotropy is due to anisotropic pair correlations where the Fe-Fe pairs are statistically preferred in-plane and the Fe-Tb pairs out-of-plane. The amplitude of this anisotropy scales with both the substrate temperature and the magnetic anisotropy energy. A ≊1% in-plane compression of the Fe-Fe distance was measured between the in-plane and out-of-plane structure of the sample grown at 77 K. This sample had no detectable local chemical anisotropy suggesting that intrinsic stress plays an important role in determining its magnetic anisotropy.

  12. Giant enhancement of magnetocrystalline anisotropy in ultrathin manganite films via nanoscale 1D periodic depth modulation

    Science.gov (United States)

    Rajapitamahuni, Anil; Zhang, Le; Singh, Vijay; Burton, John; Koten, Mak; Shield, Jeffrey; Tsymbal, Evgeny; Hong, Xia

    We report a unusual giant enhancement of in-plane magnetocrystalline anisotropy (MCA) in ultrathin colossal magnetoresistive oxide films due to 1D nanoscale periodic depth modulation. High quality epitaxial thin films of La0.67Sr0.33MnO3 (LSMO) of thickness 6 nm were grown on (001) SrTiO3 substrates via off-axis radio frequency magnetron sputtering. The top 2 nm of LSMO films are patterned into periodic nano-stripes using e-beam lithography and reactive ion etching. The resulting structure consists of nano-stripes of 2 nm height and 100-200 nm width on top of a 4 nm thick continuous base layer. We employed planar Hall effect measurements to study the in-plane magnetic anisotropy of the unpatterned and nanopatterned films. The unpatterned films show a biaxial anisotropy with easy axis along [110]. The extracted anisotropy energy density is ~1.1 x 105 erg/cm3, comparable to previously reported values. In the nanopatterned films, a strong uniaxial anisotropy is developed along one of the biaxial easy axes. The corresponding anisotropy energy density is ~5.6 x 106 erg/cm3 within the nano-striped volume, comparable to that of Co. We attribute the observed uniaxial MCA to MnO6 octahedral rotations/tilts and the enhancement in the anisotropy energy density to the strain gradient within the nano-stripes.

  13. Electrical Anisotropy in Extruded Specimens of Bi0.85Sb0.15 Solid Solution

    Science.gov (United States)

    Tagiev, М. М.

    2018-02-01

    The paper deals with the electrical anisotropy resulted from the texture formation in extruded specimens of Bi0.85Sb0.15 solid solution. Experiments show that without the magnetic field strength, in unannealed extruded specimens the electric conductivity at 77 and 300 K in the direction normal to the extrusion axis is higher than in the direction parallel to it. After annealing, an inverse correlation is observed, i.e. electrical anisotropy changes sign.

  14. Anisotropy Photoinduction during the Mass Associations of Dye Molecules in Gelatin Films

    Directory of Open Access Journals (Sweden)

    Tariel Ebralidze

    2013-01-01

    Full Text Available By using the video microscopy, the picture of the formation of anisotropy photoinduction in the form of grains in time is shown, when anisotropy in the film is induced in individual micrograins and the concentration and sizes of the grains are modulated depending on the light exposition. This phenomenon was observed in the gelatin film dyed with the mixture prepared with the saturated solutions of Chrysophenine and Acridine Yellow mixed with 1 : 1 proportion.

  15. High spatial resolution Kelvin probe force microscopy with coaxial probes

    International Nuclear Information System (INIS)

    Brown, Keith A; Westervelt, Robert M; Satzinger, Kevin J

    2012-01-01

    Kelvin probe force microscopy (KPFM) is a widely used technique to measure the local contact potential difference (CPD) between an AFM probe and the sample surface via the electrostatic force. The spatial resolution of KPFM is intrinsically limited by the long range of the electrostatic interaction, which includes contributions from the macroscopic cantilever and the conical tip. Here, we present coaxial AFM probes in which the cantilever and cone are shielded by a conducting shell, confining the tip–sample electrostatic interaction to a small region near the end of the tip. We have developed a technique to measure the true CPD despite the presence of the shell electrode. We find that the behavior of these probes agrees with an electrostatic model of the force, and we observe a factor of five improvement in spatial resolution relative to unshielded probes. Our discussion centers on KPFM, but the field confinement offered by these probes may improve any variant of electrostatic force microscopy. (paper)

  16. The BEAN experiment - An EISCAT study of ion temperature anisotropies

    Directory of Open Access Journals (Sweden)

    I. W. McCrea

    Full Text Available Results are presented from a novel EISCAT special programme, SP-UK-BEAN, intended for the direct measurement of the ion temperature anisotropy during ion frictional heating events in the high-latitude F-region. The experiment employs a geometry which provides three simultaneous estimates of the ion temperature in a single F-region observing volume at a range of aspect angles from 0° to 36°. In contrast to most previous EISCAT experiments to study ion temperature anisotropies, field-aligned observations are made using the Sodankylä radar, while the Kiruna radar measures at an aspect angle of the order of 30°. Anisotropic effects can thus be studied within a small common volume whose size and altitude range is limited by the radar beamwidth, rather than in volumes which overlap but cover different altitudes. The derivation of line-of-sight ion temperature is made more complex by the presence of an unknown percentage of atomic and molecular ions at the observing altitude and the possibility of non-Maxwellian distortion of the ion thermal velocity distribution. The first problem has been partly accounted for by insisting that a constant value of electron temperature be maintained. This enables an estimate of the ion composition to be made, and facilitates the derivation of more realistic line-of-sight ion temperatures and temperature anisotropies. The latter problem has been addressed by assuming that the thermal velocity distribution remains bi-Maxwellian. The limitations of these approaches are discussed. The ion temperature anisotropies and temperature partition coefficients during two ion heating events give values intermediate between those expected for atomic and for molecular species. This result is consistent with an analysis which indicates that significant proportions of molecular ions (up to 50% were present at the times of greatest heating.

  17. Magnetic anisotropy and magnetostriction in nanocrystalline Fe–Al alloys obtained by melt spinning technique

    Energy Technology Data Exchange (ETDEWEB)

    García, J.A.; Carrizo, J. [Depto. de Física de la Universidad de Oviedo, c/Calvo Sotelo s/n, 33007 Oviedo (Spain); Elbaile, L., E-mail: elbaile@uniovi.es [Depto. de Física de la Universidad de Oviedo, c/Calvo Sotelo s/n, 33007 Oviedo (Spain); Lago-Cachón, D.; Rivas, M. [Depto. de Física de la Universidad de Oviedo, c/Calvo Sotelo s/n, 33007 Oviedo (Spain); Castrillo, D. [Depto. de Ciencias de los Materiales de la Universidad de Oviedo, c/Independencia, 33004 Oviedo (Spain); Pierna, A.R. [Depto. de Ingeniería Química y Medio Ambiente, EUPSS, UPV/EHU, San Sebastián (Spain)

    2014-12-15

    A study about the magnetic anisotropy and magnetostriction in ribbons of composition Fe{sub 81}Al{sub 19} and Fe{sub 70}Al{sub 30} obtained by the melt spinning technique is presented. The hysteresis loops indicate that the easy magnetization direction lies in both cases on the plane of the ribbon. Torque magnetometry measurements show that the in-plane magnetic anisotropy constant results 10100 J m{sup −3} and 490 J m{sup −3} for the Fe{sub 81}Al{sub 19} and Fe{sub 70}Al{sub 30} respectively. After a thermal treatment of 2 h at 473 K to remove the residual stresses, the in-plane magnetic anisotropy constants falls down to 2500 J m{sup −3} in the first composition and remains the same in the second one, while the easy direction remains the same. Measurements of the magnetostriction and the residual stresses of both ribbons allow us to explain the above mentioned results about the magnetic anisotropy and to conclude that the residual stresses via magnetostriction are the main source of magnetic anisotropy in the case of Fe{sub 81}Al{sub 19} ribbon but they do not influence this property in the ribbon of composition Fe{sub 70}Al{sub 30}. - Highlights: • The origin of magnetic anisotropy of Fe{sub 81}Al{sub 19} and Fe{sub 70}Al{sub 30} ribbons has been studied. • The magnetic anisotropy lies in the plane of the ribbons. • A huge difference in magnetic anisotropy between two ribbons has been observed. • Magnetostriction and residual stresses explain the magnetic anisotropy in Fe{sub 81}Al{sub 19} ribbon.

  18. CMB statistical anisotropies of classical and quantum origins

    International Nuclear Information System (INIS)

    Chen, Xingang; Emami, Razieh; Firouzjahi, Hassan; Wang, Yi

    2015-01-01

    We examine the impact of different anisotropic relics on inflation, in particular the predictions on the density perturbations. These relics can be the source of the large scale anomalies in the cosmic microwave background. There are two different types of background relics, one from the matter sector and the other purely from the metric. Although the angular-dependence of the statistical anisotropy in both cases are degenerate, the scale-dependence are observationally distinctive. In addition, we demonstrate that non-Bunch-Davies vacuum states can extend the statistical anisotropy to much shorter scales, and leave a scale-dependence that is insensitive to the different backgrounds but sensitive to the initial quantum state

  19. Magnetic anisotropy and quantized spin waves in hematite nanoparticles

    DEFF Research Database (Denmark)

    Klausen, Stine Nyborg; Lefmann, Kim; Lindgård, Per-Anker

    2004-01-01

    We report on the observation of high-frequency collective magnetic excitations, (h) over bar omegaapproximate to1.1 meV, in hematite (alpha-Fe2O3) nanoparticles. The neutron scattering experiments include measurements at temperatures in the range 6-300 K and applied fields up to 7.5 T as well...... as polarization analysis. We give an explanation for the field- and temperature dependence of the excitations, which are found to have strongly elliptical out-of-plane precession. The frequency of the excitations gives information on the magnetic anisotropy constants in the system. We have in this way determined...... the temperature dependence of the magnetic anisotropy, which is strongly related to the suppression of the Morin transition in nanoparticles of hematite. Further, the localization of the signal in both energy and momentum transfer brings evidence for finite-size quantization of spin waves in the system....

  20. CMB statistical anisotropies of classical and quantum origins

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Xingang [Department of Physics, The University of Texas at Dallas, Richardson, TX 75083 (United States); Emami, Razieh [School of Physics, Institute for Research in Fundamental Sciences (IPM), P.O. Box 19395-5531, Tehran (Iran, Islamic Republic of); Firouzjahi, Hassan [School of Astronomy, Institute for Research in Fundamental Sciences (IPM), P.O. Box 19395-5531, Tehran (Iran, Islamic Republic of); Wang, Yi, E-mail: Xingang.Chen@utdallas.edu, E-mail: emami@ipm.ir, E-mail: firouz@ipm.ir, E-mail: yw366@cam.ac.uk [Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong (China)

    2015-04-01

    We examine the impact of different anisotropic relics on inflation, in particular the predictions on the density perturbations. These relics can be the source of the large scale anomalies in the cosmic microwave background. There are two different types of background relics, one from the matter sector and the other purely from the metric. Although the angular-dependence of the statistical anisotropy in both cases are degenerate, the scale-dependence are observationally distinctive. In addition, we demonstrate that non-Bunch-Davies vacuum states can extend the statistical anisotropy to much shorter scales, and leave a scale-dependence that is insensitive to the different backgrounds but sensitive to the initial quantum state.

  1. Interaction Between Downwelling Flow and the Laterally-Varying Thickness of the North American Lithosphere Inferred from Seismic Anisotropy

    Science.gov (United States)

    Behn, M. D.; Conrad, C. P.; Silver, P. G.

    2005-12-01

    Shear flow in the asthenosphere tends to align olivine crystals in the direction of shear, producing a seismically anisotropic asthenosphere that can be detected using a number of seismic techniques (e.g., shear-wave splitting (SWS) and surface waves). In the ocean basins, where the asthenosphere has a relatively uniform thickness and lithospheric anisotropy appears to be small, observed azimuthal anisotropy is well fit by asthenospheric shear flow in global flow models driven by a combination of plate motions and mantle density heterogeneity. In contrast, beneath the continents both the lithospheric ceiling and asthenospheric thickness may vary considerably across cratonic regions and ocean-continent boundaries. To examine the influence of a continental lithosphere with variable thickness on predictions of continental seismic anisotropy, we impose lateral variations in lithospheric viscosity in global models of mantle flow driven by plate motions and mantle density heterogeneity. For the North American continent, the Farallon slab descends beneath a deep cratonic root, producing downwelling flow in the upper mantle and convergent flow beneath the cratonic lithosphere. We evaluate both the orientation of the predicted azimuthal anisotropy and the depth dependence of radial anisotropy for this downwelling flow and find that the inclusion of a strong continental root provides an improved fit to observed SWS observations beneath the North American craton. Thus, we hypothesize that at least some continental anisotropy is associated with sub-lithospheric viscous shear, although fossil anisotropy in the lithospheric layer may also contribute significantly. Although we do not observe significant variations in the direction of predicted anisotropy with depth, we do find that the inclusion of deep continental roots pushes the depth of the anisotropy layer deeper into the upper mantle. We test several different models of laterally-varying lithosphere and asthenosphere

  2. Observation by conductive-probe atomic force microscopy of strongly inverted surface layers at the hydrogenated amorphous silicon/crystalline silicon heterojunctions

    Science.gov (United States)

    Maslova, O. A.; Alvarez, J.; Gushina, E. V.; Favre, W.; Gueunier-Farret, M. E.; Gudovskikh, A. S.; Ankudinov, A. V.; Terukov, E. I.; Kleider, J. P.

    2010-12-01

    Heterojunctions made of hydrogenated amorphous silicon (a-Si:H) and crystalline silicon (c-Si) are examined by conducting probe atomic force microscopy. Conductive channels at both (n )a-Si:H/(p)c-Si and (p)a-Si:H/(n)c-Si interfaces are clearly revealed. These are attributed to two-dimension electron and hole gases due to strong inversion layers at the c-Si surface in agreement with previous planar conductance measurements. The presence of a hole gas in (p )a-Si:H/(n)c-Si structures implies a quite large valence band offset (EVc-Si-EVa-Si:H>0.25 eV).

  3. Characterizing crustal and uppermost mantle anisotropy with a depth-dependent tilted hexagonally symmetric elastic tensor: theory and examples

    Science.gov (United States)

    Feng, L.; Xie, J.; Ritzwoller, M. H.

    2017-12-01

    Two major types of surface wave anisotropy are commonly observed by seismologists but are only rarely interpreted jointly: apparent radial anisotropy, which is the difference in propagation speed between horizontally and vertically polarized waves inferred from Love and Rayleigh waves, and apparent azimuthal anisotropy, which is the directional dependence of surface wave speeds (usually Rayleigh waves). We describe a method of inversion that interprets simultaneous observations of radial and azimuthal anisotropy under the assumption of a hexagonally symmetric elastic tensor with a tilted symmetry axis defined by dip and strike angles. With a full-waveform numerical solver based on the spectral element method (SEM), we verify the validity of the forward theory used for the inversion. We also present two examples, in the US and Tibet, in which we have successfully applied the tomographic method to demonstrate that the two types of apparent anisotropy can be interpreted jointly as a tilted hexagonally symmetric medium.

  4. Lithospheric deformation inferred from electrical anisotropy of magnetotelluric data

    Science.gov (United States)

    Yin, Y.; Wei, W.; Jin, S.; Ye, G.; Unsworth, M. J.; Zhang, L.

    2013-12-01

    In our research, a comprehensive procedure of analyzing and modeling electrical anisotropy for MT data is suggested, based on the field examples of the Great Slave Lake shear zone (GSLsz) in western Canada, the North China Craton (NCC) and the Altyn Tagh fault in northern Tibet. Diverse dimensionality tools are used to distinguish heterogeneity and anisotropy from MT data. In addition to the phase splits and phase tensor polarizations, a combination of the phase tensor and induction arrows is applied to judge anisotropy. The skin depths of specific period band are considered to determine whether these features result from anisotropy or heterogeneity. Specific resistivity structures in the 2-D isotropic inversion models can indicate electrical anisotropy as well, like the dike-like media or a series of conductive ';blobs' can be observed in the 2-D isotropic inversion models of the GSLsz and NCC data. Anisotropic inversions can be undertaken using an improved inversion code based on isotropic code but incorporating a trade-off parameter for electrical anisotropy named anisotropic tau. A series of anisotropic tau have been applied to test its effect and to get a best trade-off between anisotropy and heterogeneity. Then, 2-D and 3-D forward modeling works are undertaken to test the robustness of the major anisotropic features. The anisotropic structures inferred from the inversion models are replaced by various alternating isotropic or anisotropic structures to see if they are required. The fitting of the response curves compared with the field data and corresponding r.m.s misfits can help us choose the best model that can generally illustrate the underground structure. Finally, the analysis and modeling result of the MT data from North China Craton is taken as an example to demonstrate how the electrical anisotropy can be linked with the lithospheric deformation. According to the reliable models we got, there may be an anisotropic layer at the mid-lower crustal to

  5. Strong crustal seismic anisotropy in the Kalahari Craton based on Receiver Functions

    DEFF Research Database (Denmark)

    Thybo, Hans; Soliman, Mohammad Youssof Ahmad; Artemieva, Irina

    2015-01-01

    anisotropy in the crust of the Kalahari craton, which is 30-40% of the total anisotropy as measured by SKS splitting. Our analysis is based on calculation of receiver functions for the data from the SASE experiment which shows strong splitting between the SV and SH components. The direction of the fast axes...... is uniform within tectonic units and parallel to orogenic strike in the Limpopo and Cape fold belts. It is further parallel to the strike of major dyke swarms which indicates that a large part of the observed anisotropy is controlled by lithosphere fabrics and macroscopic effects. The directions of the fast...... axes for the crustal anisotropy are parallel to the general directions determined from SKS splitting, although the directions from our analysis of receiver functions is more homogeneous than for SKS splitting. This analysis indicates parallel fast axes in the crust and in the mantle, which suggests...

  6. Depth of anisotropy in the North American craton from surface wave polarizations

    Science.gov (United States)

    Maupin, V.; Pettersen, O.

    2009-04-01

    Analysis of P-wave traveltimes has shown the the North American craton is characterized by a coherent pattern of anisotropy with significant dip of the fast axis in some regions. The depth distribution of the anisotropy is however little constrained by P-wave analysis, limiting the geodynamical interpretation of the model. Surface wave polarizations are very sensitive to dip of anisotropy and can provide the missing depth-constraint to the model. We present an analysis of surface wave polarizations recorded at a number of stations on the North American craton. We show that the frequency range in which we do not observe polarization anomalies implies that the dipping anisotropy is not located in the upper part of the lithosphere.

  7. Planck early results. XVIII. The power spectrum of cosmic infrared background anisotropies

    DEFF Research Database (Denmark)

    Poutanen, T.; Natoli, P.; Polenta, G.

    2011-01-01

    Using Planck maps of six regions of low Galactic dust emission with a total area of about 140 deg2, we determine the angular power spectra of cosmic infrared background (CIB) anisotropies from multipole = 200 to = 2000 at 217, 353, 545 and 857 GHz. We use 21-cm observations of Hi as a tracer...... of thermal dust emission to reduce the already low level of Galactic dust emission and use the 143 GHz Planck maps in these fields to clean out cosmic microwave background anisotropies. Both of these cleaning processes are necessary to avoid significant contamination of the CIB signal. We measure correlated...... CIB structure across frequencies. As expected, the correlation decreases with increasing frequency separation, because the contribution of high-redshift galaxies to CIB anisotropies increases with wavelengths. We find no significant difference between the frequency spectrum of the CIB anisotropies...

  8. RADIO SYNCHROTRON FLUCTUATION STATISTICS AS A PROBE OF MAGNETIZED INTERSTELLAR TURBULENCE

    International Nuclear Information System (INIS)

    Herron, C. A.; Gaensler, B. M.; Burkhart, Blakesley; Lazarian, A.; McClure-Griffiths, N. M.

    2016-01-01

    We investigate how observations of synchrotron intensity fluctuations can be used to probe the sonic and Alfvénic Mach numbers of interstellar turbulence, based on mock observations performed on simulations of magnetohydrodynamic turbulence. We find that the structure function slope and a diagnostic of anisotropy that we call the integrated quadrupole ratio modulus both depend on the Alfvénic Mach number. However, these statistics also depend on the orientation of the mean magnetic field in the synchrotron emitting region relative to our line of sight, and this creates a degeneracy that cannot be broken by observations of synchrotron intensity alone. We conclude that the polarization of synchrotron emission could be analyzed to break this degeneracy, and suggest that this will be possible with the Square Kilometre Array.

  9. RADIO SYNCHROTRON FLUCTUATION STATISTICS AS A PROBE OF MAGNETIZED INTERSTELLAR TURBULENCE

    Energy Technology Data Exchange (ETDEWEB)

    Herron, C. A.; Gaensler, B. M. [Sydney Institute for Astronomy, School of Physics, University of Sydney, New South Wales 2006 (Australia); Burkhart, Blakesley [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA (United States); Lazarian, A. [Astronomy Department, University of Wisconsin, Madison, 475 N. Charter Street, WI 53711 (United States); McClure-Griffiths, N. M., E-mail: C.Herron@physics.usyd.edu.au [Research School of Astronomy and Astrophysics, The Australian National University, Canberra, ACT 2611 (Australia)

    2016-05-01

    We investigate how observations of synchrotron intensity fluctuations can be used to probe the sonic and Alfvénic Mach numbers of interstellar turbulence, based on mock observations performed on simulations of magnetohydrodynamic turbulence. We find that the structure function slope and a diagnostic of anisotropy that we call the integrated quadrupole ratio modulus both depend on the Alfvénic Mach number. However, these statistics also depend on the orientation of the mean magnetic field in the synchrotron emitting region relative to our line of sight, and this creates a degeneracy that cannot be broken by observations of synchrotron intensity alone. We conclude that the polarization of synchrotron emission could be analyzed to break this degeneracy, and suggest that this will be possible with the Square Kilometre Array.

  10. Kinetic instabilities in the solar wind driven by temperature anisotropies

    Science.gov (United States)

    Yoon, Peter H.

    2017-12-01

    The present paper comprises a review of kinetic instabilities that may be operative in the solar wind, and how they influence the dynamics thereof. The review is limited to collective plasma instabilities driven by the temperature anisotropies. To limit the scope even further, the discussion is restricted to the temperature anisotropy-driven instabilities within the model of bi-Maxwellian plasma velocity distribution function. The effects of multiple particle species or the influence of field-aligned drift will not be included. The field-aligned drift or beam is particularly prominent for the solar wind electrons, and thus ignoring its effect leaves out a vast portion of important physics. Nevertheless, for the sake of limiting the scope, this effect will not be discussed. The exposition is within the context of linear and quasilinear Vlasov kinetic theories. The discussion does not cover either computer simulations or data analyses of observations, in any systematic manner, although references will be made to published works pertaining to these methods. The scientific rationale for the present analysis is that the anisotropic temperatures associated with charged particles are pervasively detected in the solar wind, and it is one of the key contemporary scientific research topics to correctly characterize how such anisotropies are generated, maintained, and regulated in the solar wind. The present article aims to provide an up-to-date theoretical development on this research topic, largely based on the author's own work.

  11. Magnetic anisotropies in ultrathin bismuth iron garnet films

    International Nuclear Information System (INIS)

    Popova, Elena; Franco Galeano, Andres Felipe; Deb, Marwan; Warot-Fonrose, Bénédicte; Kachkachi, Hamid; Gendron, François; Ott, Frédéric

    2013-01-01

    Ultrathin bismuth iron garnet Bi 3 Fe 5 O 12 films were grown epitaxially on (001)-oriented gadolinium gallium garnet substrates. Film thickness varied from two to three dozens of unit cells. Bi 3 Fe 5 O 12 films grow pseudomorphically on substrates up to a thickness of 20 nm, and then a lattice relaxation occurs. Magnetic properties of the films were studied as a function of bismuth iron garnet thickness. The magnetization and cubic anisotropy decrease with decreasing film thickness. The uniaxial magnetocrystalline anisotropy is constant for all film thicknesses. For two unit cell thick films, the easy magnetization axis changes from in-plane to perpendicular to the plane direction. Such a reorientation takes place as a result of the competition of constant uniaxial perpendicular anisotropy with weakening film magnetization. - Highlights: ► Ultrathin Bi 3 Fe 5 O 12 films were grown epitaxially on structure-matching substrates. ► Magnetic properties of Bi 3 Fe 5 O 12 were studied down to the thickness of 2.5 nm. ► Reorientation of easy magnetization axis as a function of film thickness was observed

  12. Magnetic anisotropies in ultrathin bismuth iron garnet films

    Energy Technology Data Exchange (ETDEWEB)

    Popova, Elena, E-mail: popova@physique.uvsq.fr [Groupe d' Etude de la Matière Condensée (GEMaC), CNRS/Université de Versailles-Saint-Quentin, 45 Avenue des Etats-Unis, 78035 Versailles (France); Franco Galeano, Andres Felipe [Laboratoire PROcédés, Matériaux et Energie Solaire (PROMES), CNRS/Université de Perpignan Via Domitia, 52 Avenue Paul Alduy, 66860 Perpignan (France); Deb, Marwan [Groupe d' Etude de la Matière Condensée (GEMaC), CNRS/Université de Versailles-Saint-Quentin, 45 Avenue des Etats-Unis, 78035 Versailles (France); Warot-Fonrose, Bénédicte [Centre d' Elaboration de Matériaux et d' Etudes Structurales (CEMES), CNRS, 29 rue Jeanne Marvig, 31055 Toulouse (France); Transpyrenean Associated Laboratory for Electron Microscopy (TALEM), CEMES-INA, CNRS–Universidad de Zaragoza (Spain); Kachkachi, Hamid [Laboratoire PROcédés, Matériaux et Energie Solaire (PROMES), CNRS/Université de Perpignan Via Domitia, 52 Avenue Paul Alduy, 66860 Perpignan (France); Gendron, François [Institut des NanoSciences de Paris (INSP), CNRS/Université Pierre et Marie Curie-Paris 6, 4 place Jussieu, Boîte courrier 840, 75252 Paris Cedex 05 (France); Ott, Frédéric [Laboratoire Léon Brillouin (LLB), CNRS/CEA, Bâtiment 563, CEA Saclay, 91191 Gif sur Yvette Cedex (France); and others

    2013-06-15

    Ultrathin bismuth iron garnet Bi{sub 3}Fe{sub 5}O{sub 12} films were grown epitaxially on (001)-oriented gadolinium gallium garnet substrates. Film thickness varied from two to three dozens of unit cells. Bi{sub 3}Fe{sub 5}O{sub 12} films grow pseudomorphically on substrates up to a thickness of 20 nm, and then a lattice relaxation occurs. Magnetic properties of the films were studied as a function of bismuth iron garnet thickness. The magnetization and cubic anisotropy decrease with decreasing film thickness. The uniaxial magnetocrystalline anisotropy is constant for all film thicknesses. For two unit cell thick films, the easy magnetization axis changes from in-plane to perpendicular to the plane direction. Such a reorientation takes place as a result of the competition of constant uniaxial perpendicular anisotropy with weakening film magnetization. - Highlights: ► Ultrathin Bi{sub 3}Fe{sub 5}O{sub 12} films were grown epitaxially on structure-matching substrates. ► Magnetic properties of Bi{sub 3}Fe{sub 5}O{sub 12} were studied down to the thickness of 2.5 nm. ► Reorientation of easy magnetization axis as a function of film thickness was observed.

  13. Cosmic ray anisotropy: 1012 - 1020eV

    International Nuclear Information System (INIS)

    Watson, A.A.

    1981-01-01

    The results of experiments designed to study the arrival direction distribution of cosmic rays of energy 10 12 - 10 20 eV are reviewed. It is shown that at all energies there is evidence for anisotropy, the amplitude of which ranges from 0.75% at the lowest energies to 90+-20% above 4.10 19 eV. The increase of anisotropy with energy is not smooth, showing features which occur at energies similar to those at which features are observed in the cosmic ray energy spectrum. At least up to 2.10 17 eV it seems probable that the acceleration sites lie within our Galaxy, and it is hard to escape the conclusion that particles of energy >10 19 eV are extragalactic. Sources of the highest energy particles (approximately 10 20 eV) must lie within 200Mpc, and considerably closer if, as seems likely, the intergalactic medium is such as to prevent rectilinear propagation. Between 2.10 17 and 10 19 eV the location of the sources is less certain. The aim of future arrival direction experiments should be to study anisotropy as a function of primary mass composition

  14. Flux and anisotropy of galactic cosmic rays: beyond homogeneous models

    International Nuclear Information System (INIS)

    Bernard, Guilhem

    2013-01-01

    In this thesis I study the consequence of non homogeneously distributed cosmic ray sources in the Milky way. The document starts with theoretical and experimental synthesis. Firstly, I will describe the interstellar medium to understand the mechanism of propagation and acceleration of cosmic rays. Then, the detailed study of cosmic rays diffusion on the galactic magnetic field allows to write a commonly used propagation equation. I will recall the Steady-state solutions of this equation, then I will focus on the time dependant solutions with point-like sources. A statistical study is performed in order to estimate the standard deviation of the flux around its mean value. The computation of this standard deviation leads to mathematical divergences. Thus, I will develop statistical tools to bypass this issue. So i will discuss the effect of the granularity of cosmic ray sources. Its impact on cosmic ray spectrum can explain some recent features observed by the experiments CREAM and PAMELA.Besides, this thesis is focused on the study of the anisotropy of cosmic rays. I will recap experimental methods of measurements, and I will show how to connect theoretical calculation from propagation theories to experimental measurements. Then, the influence of the local environment on the anisotropy measurements will be discussed, particularly the effect of a local diffusion coefficient. Then, I will compute anisotropy and its variance in a framework of point-like local sources with the tools developed in the first part. Finally, the possible influence of local sources on the anisotropy is discussed in the light of the last experimental results. (author) [fr

  15. Report on 1988 research result on the R and D of observation system for probing resources. 2/3; 1988 nendo shigen tansayo kansoku system no kenkyu kaihatsu. 2/3

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1989-07-01

    This paper explains the 1988 results of the specialized study in the R and D of the observation system for probing resources. In the interface with the satellite body, the result of the 1986 basic design was reexamined, elucidating the interface conditions, while the telemetry command items were also rechecked, clarifying the restrictions of the operation. In addition, the combination tests of mission equipment were all put together. Reexamined also were the interface specifications of optical sensors. Concerning the interface between the satellite body and the mission transmitter, examination was made on the detailed design level. In the operation mission analysis, algorithm for acquiring mission equipment data was reviewed, as were the operation analysis program and the data acquiring simulation. With a case examined in which an optical sensor satellite image was used for probing oil, the conclusion was obtained that the present design specifications were sufficient. In the experiment of the on-aircraft multi-channel image sensor, the subject sensor was found much higher than before in the performance for identifying rocks/minerals and was expected to be useful for resource probes. Image analysis of the test site was also performed. (NEDO)

  16. Theoretical aspects for estimating anisotropic saturated hydraulic conductivity from in-well or direct-push probe injection tests in uniform media

    Science.gov (United States)

    Klammler, Harald; Layton, Leif; Nemer, Bassel; Hatfield, Kirk; Mohseni, Ana

    2017-06-01

    Hydraulic conductivity and its anisotropy are fundamental aquifer properties for groundwater flow and transport modeling. Current in-well or direct-push field measurement techniques allow for relatively quick determination of general conductivity profiles with depth. However, capabilities for identifying local scale conductivities in the horizontal and vertical directions are very limited. Here, we develop the theoretical basis for estimating horizontal and vertical conductivities from different types of steady-state single-well/probe injection tests under saturated conditions and in the absence of a well skin. We explore existing solutions and a recent semi-analytical solution approach to the flow problem under the assumption that the aquifer is locally homogeneous. The methods are based on the collection of an additional piece of information in the form of a second injection (or recirculation) test at a same location, or in the form of an additional head or flow observation along the well/probe. Results are represented in dimensionless charts for partial validation against approximate solutions and for practical application to test interpretation. The charts further allow for optimization of a test configuration to maximize sensitivity to anisotropy ratio. The two methods most sensitive to anisotropy are found to be (1) subsequent injection from a lateral screen and from the bottom of an otherwise cased borehole, and (2) single injection from a lateral screen with an additional head observation along the casing. Results may also be relevant for attributing consistent divergences in conductivity measurements from different testing methods applied at a same site or location to the potential effects of anisotropy. Some practical aspects are discussed and references are made to existing methods, which appear easily compatible with the proposed procedures.

  17. Variation in the strain anisotropy of Zircaloy with temperature and strain

    International Nuclear Information System (INIS)

    Hindle, E.D.; Worswick, D.

    1984-04-01

    Strain anisotropy was investigated at temperatures in the range 293 to 1117K in circular tensile specimens prepared from rolled Zircaloy-2 plate so that their tensile axes were parallel to and transverse to the rolling direction. The strain anisotropy factor for both types of specimen increased markedly in the high alpha phase region above 923K reaching a maximum at circa 1070K. Above this temperature in the alpha-plus-beta phase region the strain anisotropy decreased rapidly as the proportion of beta phase increased and was almost non-existent at 1173K. The strain anisotropy was markedly strain dependent, particularly in the high alpha phase region. The study was extended to Zircaloy-4 pressurized water reactor (PWR) 17 x 17 type fuel rod tubing specimens which were strained under biaxial conditions using cooling conditions which promoted uniform diametral strain over most of their lengths (circa 250 mm). In these circumstances the strain anisotropy is manifest by a reduction in length. Measurement of this change along with that in diameter and wall thickness produced data from which the strain anisotropy factor was calculated. The results, although influenced by additional factors discussed in the paper, were similar to those observed in the uniaxial Zircaloy-2 tensile tests. (author)

  18. Origin and spectroscopic determination of trigonal anisotropy in a heteronuclear single-molecule magnet

    Science.gov (United States)

    Sorace, L.; Boulon, M.-E.; Totaro, P.; Cornia, A.; Fernandes-Soares, J.; Sessoli, R.

    2013-09-01

    W-band (ν ≅ 94 GHz) electron paramagnetic resonance (EPR) spectroscopy was used for a single-crystal study of a star-shaped Fe3Cr single-molecule magnet (SMM) with crystallographically imposed trigonal symmetry. The high resolution and sensitivity accessible with W-band EPR allowed us to determine accurately the axial zero-field splitting terms for the ground (S = 6) and first two excited states (S = 5 and S = 4). Furthermore, spectra recorded by applying the magnetic field perpendicular to the trigonal axis showed a π/6 angular modulation. This behavior is a signature of the presence of trigonal transverse magnetic anisotropy terms whose values had not been spectroscopically determined in any SMM prior to this work. Such in-plane anisotropy could only be justified by dropping the so-called “giant spin approach” and by considering a complete multispin approach. From a detailed analysis of experimental data with the two models, it emerged that the observed trigonal anisotropy directly reflects the structural features of the cluster, i.e., the relative orientation of single-ion anisotropy tensors and the angular modulation of single-ion anisotropy components in the hard plane of the cluster. Finally, since high-order transverse anisotropy is pivotal in determining the spin dynamics in the quantum tunneling regime, we have compared the angular dependence of the tunnel splitting predicted by the two models upon application of a transverse field (Berry-phase interference).

  19. Measurement of the distribution of anisotropy constants in magnetic nanoparticles for hyperthermia applications

    Science.gov (United States)

    McGhie, A. A.; Marquina, C.; O'Grady, K.; Vallejo-Fernandez, G.

    2017-11-01

    In this work, we have applied theoretical calculations to new experimental measurements of the effect of the anisotropy distribution in magnetite nanoparticles, which in turn controls hysteresis heating for hyperthermia applications. Good agreement between theory and experiment is reported where the theoretical calculation is based upon the detailed measurement of the particle elongation generally observed in the nanoparticles. The elongation has been measured from studies via transmission electron microscopy. We find that particle elongation is responsible for the anisotropy dispersion, which can be obtained by analysis and fitting to a measurement of the temperature decay of remanence. A median value of the anisotropy constant of 1.5  ×  105 erg/cc was obtained. A very wide distribution of anisotropy constants is present with a Gaussian standard deviation of 1.5  ×  105 erg/cc. From our measurements, deviations in the value of the saturation magnetisation from particle to particle are most likely the main factor giving rise to this large distribution, with 33% arising from the error in the measured elongation. The lower limit to the anisotropy constant of the nanoparticles is determined by the magnetocrystalline anisotropy of the material, 1.1  ×  105 erg/cc for magnetite, which was studied in this work.

  20. Reconciling experimental and static-dynamic numerical estimations of seismic anisotropy in Alpine Fault mylonites

    Science.gov (United States)

    Adam, L.; Frehner, M.; Sauer, K. M.; Toy, V.; Guerin-Marthe, S.; Boulton, C. J.

    2017-12-01

    Reconciling experimental and static-dynamic numerical estimations of seismic anisotropy in Alpine Fault mylonitesLudmila Adam1, Marcel Frehner2, Katrina Sauer3, Virginia Toy3, Simon Guerin-Marthe4, Carolyn Boulton5(1) University of Auckland, New Zealand, (2) ETH Zurich, Switzerland, (3) University of Otago, New Zealand (4) Durham University, Earth Sciences, United Kingdom (5) Victoria University of Wellington, New Zealand Quartzo-feldspathic mylonites and schists are the main contributors to seismic wave anisotropy in the vicinity of the Alpine Fault (New Zealand). We must determine how the physical properties of rocks like these influence elastic wave anisotropy if we want to unravel both the reasons for heterogeneous seismic wave propagation, and interpret deformation processes in fault zones. To study such controls on velocity anisotropy we can: 1) experimentally measure elastic wave anisotropy on cores at in-situ conditions or 2) estimate wave velocities by static (effective medium averaging) or dynamic (finite element) modelling based on EBSD data or photomicrographs. Here we compare all three approaches in study of schist and mylonite samples from the Alpine Fault. Volumetric proportions of intrinsically anisotropic micas in cleavage domains and comparatively isotropic quartz+feldspar in microlithons commonly vary significantly within one sample. Our analysis examines the effects of these phases and their arrangement, and further addresses how heterogeneity influences elastic wave anisotropy. We compare P-wave seismic anisotropy estimates based on millimetres-scale ultrasonic waves under in situ conditions, with simulations that account for micrometre-scale variations in elastic properties of constitutent minerals with the MTEX toolbox and finite-element wave propagation on EBSD images. We observe that the sorts of variations in the distribution of micas and quartz+feldspar within any one of our real core samples can change the elastic wave anisotropy by 10

  1. Fracture characterization using frequency-dependent shear wave anisotropy analysis of microseismic data

    Science.gov (United States)

    Al-Harrasi, O. H.; Kendall, J.-M.; Chapman, M.

    2011-05-01

    The presence of fractures in hydrocarbon reservoirs can enhance porosity and permeability, and consequently increase production. The use of seismic anisotropy to characterize fracture systems has gained much interest in the last two decades. However, estimating fracture sizes from observations of seismic anisotropy has not been possible. Recent work has shown that frequency-dependent anisotropy (FDA) is very sensitive to the length-scale of the causative mechanism for the anisotropy. In this study, we observe FDA in a microseismic data set acquired from a carbonate gas field in Oman. The frequency-dependent shear wave anisotropy observations are modelled using a poroelastic model, which considers fluid communication between grain size pore spaces and larger scale fractures. A grid search is performed over fracture parameters (radius, density and strike) to find the model that best fits the real data. The results show that fracture size varies from the microscale within the shale cap rocks, to the metre-scale within the gas reservoir, to the centimetre-scale within the non-producing part of the carbonate formation. The lateral variation in fracture density agrees with previous conclusions from ordinary shear wave splitting (SWS) analysis. Cumulatively, the results show the potential for characterizing fracture systems using observations of FDA.

  2. Seismic anisotropy beneath NW Himalaya using SKS and SKKS Splitting measurements

    Science.gov (United States)

    Biswal, S.; Kumar, S.; Mohanty, W. K.

    2016-12-01

    Seventy six teleseismic earthquakes comprising of both SKS and SKKS were analysed for the NW Himalaya to infer the characteristics of the shear wave splitting parameters in the region. The anisotropy results obtained from the analysis shows upper mantle anisotropy in the study area with the fast axis aligned along a NNE-SSW direction and the average delay times observed at the station ranges from a minimum of 0.3s to a maximum of 1.7s for SKS and SKKS phases. These splitting results obtained for this area shows a parallel trend with motion of the India plate as estimated from NUVEL 1A model in contradiction to the orthogonal E-W trend observed for the NE Himalaya observed at the collision front. The seismic anisotropy observed in this region demarcates a shallow source of anisotropy that may be due to the strain flow in the upper mantle which may be the causative source of the anisotropy in the region.

  3. Role of the substrate on the magnetic anisotropy of magnetite thin films grown by ion-assisted deposition

    Energy Technology Data Exchange (ETDEWEB)

    Prieto, Pilar, E-mail: pilar.prieto@uam.es [Dpto. Física Aplicada M-12, Universidad Autónoma de Madrid, 28049 Madrid (Spain); Prieto, José Emilio [Centro de Microanálisis de Materiales (CMAM) and Dpto. De Física de la Materia Condensada, Universidad Autónoma de Madrid, 28049 Madrid (Spain); Gargallo-Caballero, Raquel; Marco, José Francisco; Figuera, Juan de la [Instituto de Química Física “Rocasolano”, CSIC, 28006 Madrid (Spain)

    2015-12-30

    Graphical abstract: - Highlights: • The magnetic anisotropy of magnetite thin films is controlled by the substrate induced microstructure. • Single-crystal oxide substrates induce fourfold in-plane magnetic anisotropy • MgO and SrTiO{sub 3} substrates show the same magnetic behavior despite its different mismatch with Fe{sub 3}O{sub 4} films. • Silicon and glass substrates induce in-plane magnetic isotropy and uniaxial anisotropy, respectively. - Abstract: Magnetite (Fe{sub 3}O{sub 4}) thin films were deposited on MgO (0 0 1), SrTiO{sub 3} (0 0 1), LaAlO{sub 3} (0 0 1) single crystal substrates as well on as silicon and amorphous glass in order to study the effect of the substrate on their magnetic properties, mainly the magnetic anisotropy. We have performed a structural, morphological and compositional characterization by X-ray diffraction, atomic force microscopy and Rutherford backscattering ion channeling in oxygen resonance mode. The magnetic anisotropy has been investigated by vectorial magneto-optical Kerr effect. The results indicate that the magnetic anisotropy is especially influenced by the substrate-induced microstructure. In-plane isotropy and uniaxial anisotropy behavior have been observed on silicon and glass substrates, respectively. The transition between both behaviors depends on grain size. For LaAlO{sub 3} substrates, in which the lattice mismatch between the Fe{sub 3}O{sub 4} films and the substrate is significant, a weak in-plane fourfold magnetic anisotropy is induced. However when magnetite is deposited on MgO (0 0 1) and SrTiO{sub 3} (0 0 1) substrates, a well-defined fourfold in-plane magnetic anisotropy is observed with easy axes along [1 0 0] and [0 1 0] directions. The magnetic properties on these two latter substrates are similar in terms of magnetic anisotropy and coercive fields.

  4. Polarization of Sunyaev-Zel'dovich signal due to electron pressure anisotropy in galaxy clusters

    Science.gov (United States)

    Khabibullin, I.; Komarov, S.; Churazov, E.; Schekochihin, A.

    2018-02-01

    We describe polarization of the Sunyaev-Zel'dovich (SZ) effect associated with electron pressure anisotropy likely present in the intracluster medium (ICM). The ICM is an astrophysical example of a weakly collisional plasma where the Larmor frequencies of charged particles greatly exceed their collision frequencies. This permits formation of pressure anisotropies, driven by evolving magnetic fields via adiabatic invariance, or by heat fluxes. SZ polarization arises in the process of Compton scattering of the cosmic microwave background (CMB) photons off the thermal ICM electrons due to the difference in the characteristic thermal velocities of the electrons along two mutually orthogonal directions in the sky plane. The signal scales linearly with the optical depth of the region containing large-scale correlated anisotropy, and with the degree of anisotropy itself. It has the same spectral dependence as the polarization induced by cluster motion with respect to the CMB frame (kinematic SZ effect polarization), but can be distinguished by its spatial pattern. For the illustrative case of a galaxy cluster with a cold front, where electron transport is mediated by Coulomb collisions, we estimate the CMB polarization degree at the level of 10-8 (˜10 nK). An increase of the effective electron collisionality due to plasma instabilities will reduce the effect. Such polarization, therefore, may be an independent probe of the electron collisionality in the ICM, which is one of the key properties of a high-β weakly collisional plasma from the point of view of both astrophysics and plasma theory.

  5. Inferring electromagnetic ion cyclotron wave intensity from low altitude POES proton flux measurements: A detailed case study with conjugate Van Allen Probes observations

    Science.gov (United States)

    Zhang, Yang; Shi, Run; Ni, Binbin; Gu, Xudong; Zhang, Xianguo; Zuo, Pingbing; Fu, Song; Xiang, Zheng; Wang, Qi; Cao, Xing; Zou, Zhengyang

    2017-03-01

    Electromagnetic ion cyclotron (EMIC) waves play an important role in the magnetospheric particle dynamics and can lead to resonant pitch-angle scattering and ultimate precipitation of ring current protons. Commonly, the statistics of in situ EMIC wave measurements is adopted for quantitative investigation of wave-particle interaction processes, which however becomes questionable for detailed case studies especially during geomagnetic storms and substorms. Here we establish a novel technique to infer EMIC wave amplitudes from low-altitude proton measurements onboard the Polar Operational Environmental Satellites (POES). The detailed procedure is elaborated regarding how to infer the EMIC wave intensity for one specific time point. We then test the technique with a case study comparing the inferred root-mean-square (RMS) EMIC wave amplitude with the conjugate Van Allen Probes EMFISIS wave measurements. Our results suggest that the developed technique can reasonably estimate EMIC wave intensities from low-altitude POES proton flux data, thereby providing a useful tool to construct a data-based, near-real-time, dynamic model of the global distribution of EMIC waves once the proton flux measurements from multiple POES satellites are available for any specific time period.

  6. The characteristic pitch angle distributions of 1 eV to 600 keV protons near the equator based on Van Allen Probes observations

    Science.gov (United States)

    Yue, C.; Bortnik, J.; Thorne, R. M.; Ma, Q.; An, X.; Chappell, C. R.; Gerrard, A. J.; Lanzerotti, L. J.; Shi, Q.

    2017-12-01

    Understanding the source and loss processes of various plasma populations is greatly aided by having accurate knowledge of their pitch angle distributions (PADs). Here, we statistically analyze 1 eV to 600 keV hydrogen (H+) PADs near the geomagnetic equator in the inner magnetosphere based on Van Allen Probes measurements, to comprehensively investigate how the H+ PADs vary with different energies, magnetic local times (MLTs), L-shells, and geomagnetic conditions. Our survey clearly indicates four distinct populations with different PADs: (1) a pancake distribution of the plasmaspheric H+ at low L-shells except for dawn sector; (2) a bi-directional field-aligned distribution of the warm plasma cloak; (3) pancake or isotropic distributions of ring current H+; (4) radiation belt particles show pancake, butterfly and isotropic distributions depending on their energy, MLT and L-shell. Meanwhile, the pancake distribution of ring current H+ moves to lower energies as L-shell increases which is primarily caused by adiabatic transport. Furthermore, energetic H+ (> 10 keV) PADs become more isotropic following the substorm injections, indicating wave-particle interactions. The radiation belt H+ butterfly distributions are identified in a narrow energy range of 100 5), which are less significant during quiet times and extend from dusk to dawn sector through midnight during substorms. The different PADs near the equator provide clues of the underlying physical processes that produce the dynamics of these different populations.

  7. The Characteristic Pitch Angle Distributions of 1 eV to 600 keV Protons Near the Equator Based On Van Allen Probes Observations

    Science.gov (United States)

    Yue, Chao; Bortnik, Jacob; Thorne, Richard M.; Ma, Qianli; An, Xin; Chappell, C. R.; Gerrard, Andrew J.; Lanzerotti, Louis J.; Shi, Quanqi; Reeves, Geoffrey D.; Spence, Harlan E.; Mitchell, Donald G.; Gkioulidou, Matina; Kletzing, Craig A.

    2017-09-01

    Understanding the source and loss processes of various plasma populations is greatly aided by having accurate knowledge of their pitch angle distributions (PADs). Here we statistically analyze 1 eV to 600 keV hydrogen (H+) PADs near the geomagnetic equator in the inner magnetosphere based on Van Allen Probes measurements, to comprehensively investigate how the H+ PADs vary with different energies, magnetic local times (MLTs), L shells, and geomagnetic conditions. Our survey clearly indicates four distinct populations with different PADs: (1) a pancake distribution of the plasmaspheric H+ at low L shells except for dawn sector; (2) a bidirectional field-aligned distribution of the warm plasma cloak; (3) pancake or isotropic distributions of ring current H+; (4) radiation belt particles show pancake, butterfly, and isotropic distributions depending on their energy, MLT, and L shell. Meanwhile, the pancake distribution of ring current H+ moves to lower energies as L shell increases, which is primarily caused by adiabatic transport. Furthermore, energetic H+ (>10 keV) PADs become more isotropic following the substorm injections, indicating wave-particle interactions. The radiation belt H+ butterfly distributions are identified in a narrow energy range of 100 5), which are less significant during quiet times and extend from dusk to dawn sector through midnight during substorms. The different PADs near the equator provide clues of the underlying physical processes that produce the dynamics of these different populations.

  8. Measurements of magnetic anisotropy in sickle cells

    International Nuclear Information System (INIS)

    Salvo Souza, L.H. de.

    1982-03-01

    Room temperature magnetic measurements in deoxigenated sickle cells showed the existence of magnetic anisotropy, Δchi=1,29 x 10 -3 . This effect was supposed paramagnetic and considered to be due to the iron atoms of the hemoglobin molecules which are one over the other, forming ordered chains inside the erythrocytes. Low temperature (liquid He - 4,2K) measurements of the magnetic anisotropy of sickle cells and normal red blood cells diluted in a cryoprotector was made to confirm the paramagnetic origin of the fenomena. For that purpose it was used a superconductor magnetometer coupled to a SQUID, developed in the 'Laboratorio do Estado Solido do Departamento de Fisica da PUC-RJ'. The results obtained seem to confirm the expected paramagnetic anisotropy and, furthermore, suggest the presence of magnetic interactions among the iron atoms in the sickle cells samples. (Author) [pt

  9. Radial anisotropy ambient noise tomography of volcanoes

    Science.gov (United States)

    Mordret, Aurélien; Rivet, Diane; Shapiro, Nikolai; Jaxybulatov, Kairly; Landès, Matthieu; Koulakov, Ivan; Sens-Schönfelder, Christoph

    2016-04-01

    The use of ambient seismic noise allows us to perform surface-wave tomography of targets which could hardly be imaged by other means. The frequencies involved (~ 0.5 - 20 s), somewhere in between active seismic and regular teleseismic frequency band, make possible the high resolution imaging of intermediate-size targets like volcanic edifices. Moreover, the joint inversion of Rayleigh and Love waves dispersion curves extracted from noise correlations allows us to invert for crustal radial anisotropy. We present here the two first studies of radial anisotropy on volcanoes by showing results from Lake Toba Caldera, a super-volcano in Indonesia, and from Piton de la Fournaise volcano, a hot-spot effusive volcano on the Réunion Island (Indian Ocean). We will see how radial anisotropy can be used to infer the main fabric within a magmatic system and, consequently, its dominant type of intrusion.

  10. Magnetic anisotropy engineering in square magnetic elements

    International Nuclear Information System (INIS)

    Di Bona, A.; Contri, S.F.; Gazzadi, G.C.; Valeri, S.; Vavassori, P.

    2007-01-01

    Square magnetic elements with side in the 100-500 nm range have been fabricated using the focused ion beam (FIB) milling technique from a 10 nm thick, single-crystal Fe film, epitaxially grown on MgO(0 0 1). Thanks to the good crystal quality of the film, magnetic elements with well-defined magnetocrystalline anisotropy have been prepared, while the fine control of the size and shape of the magnets allows for the effective engineering of the anisotropic behavior of the magnetostatic energy that determines the so-called configurational anisotropy. Micromagnetic calculations and experiments show that the angular dependence of the transverse susceptibility has a strong dependence on the material parameters as well as on the static applied field. This allows the effective engineering of the total anisotropy of the magnets

  11. Influence of temperature on the Zircaloy-4 plastic anisotropy; Influence de la temperature sur l`anisotropie plastique du Zircaloy-4

    Energy Technology Data Exchange (ETDEWEB)

    Limon, R.; Bechade, J.L.; Lehmann, S.; Maury, R.; Soniak, A. [CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France). Direction des Technologies Avancees; Mardon, J.P. [Societe Franco-Americaine de Constructions Atomiques (FRAMATOME), 92 - Paris-La-Defense (France)

    1995-12-31

    In order to improve the comportment modelling of PWR fuel pin, and more precisely their canning tubes, Framatome and the CEA have undertake an important study program of Zircaloy-4 mechanical properties. It includes in particular the study of the plasticity between 20 and 400 degree Celsius. This material being not isotropic because of the zirconium hexagonal crystal network and the texture presented by the canning tubes, its plastic anisotropy has been measured. The obtained results for the canning in *slack* and recrystallized before irradiation Zircaloy-4 are presented and the deformation systems able to explain the observed anisotropy is researched. (O.L.). 6 refs., 4 figs., 1 tab.

  12. Direct fluorescence anisotropy assay for cocaine using tetramethylrhodamine-labeled aptamer.

    Science.gov (United States)

    Liu, Yingxiong; Zhao, Qiang

    2017-06-01

    Development of simple, sensitive, and rapid method for cocaine detection is important in medicine and drug abuse monitoring. Taking advantage of fluorescence anisotropy and aptamer, this study reports a direct fluorescence anisotropy (FA) assay for cocaine by employing an aptamer probe with tetramethylrhodamine (TMR) labeled on a specific position. The binding of cocaine and the aptamer causes a structure change of the TMR-labeled aptamer, leading to changes of the interaction between labeled TMR and adjacent G bases in aptamer sequence, so FA of TMR varies with increasing of cocaine. After screening different labeling positions of the aptamer, including thymine (T) bases and terminals of the aptamer, we obtained a favorable aptamer probe with TMR labeled on the 25th base T in the sequence, which exhibited sensitive and significant FA-decreasing responses upon cocaine. Under optimized assay conditions, this TMR-labeled aptamer allowed for direct FA detection of cocaine as low as 5 μM. The maximum FA change reached about 0.086. This FA method also enabled the detection of cocaine spiked in diluted serum and urine samples, showing potential for applications. Graphical Abstract The binding of cocaine to the TMR-labeled aptamer causes conformation change and alteration of the intramolecular interaction between TMR and bases of aptamer, leading to variance of fluorescence anisotropy (FA) of TMR, so direct FA analyis of cocaine is achieved.

  13. Anisotropy of the Topopah Spring Member Tuff

    International Nuclear Information System (INIS)

    Martin, R.J. III; Boyd, P.J.; Haupt, R.W.; Price, R.H.

    1992-07-01

    Mechanical properties of the tuffaceous rocks within Yucca Mountain are needed for near and far-field modeling of the potential nuclear waste repository. If the mechanical properties are significantly anisotropic (i.e., direction-dependent), a more complex model is required. Relevant data from tuffs tested in earlier studies indicate that elastic and strength properties are anisotropic. This scoping study confirms the elastic anisotropy and concludes some tuffs are transversely isotropic. An approach for sampling and testing the rock to determine the magnitude of the anisotropy is proposed

  14. Anisotropy of dilepton emission from nuclear collisions

    International Nuclear Information System (INIS)

    Bratkovskaya, E.L.; Teryaev, O.V.; Toneev, V.D.; Joint Inst. for Nuclear Research, Dubna

    1994-01-01

    Attention is paid to studying the angular characteristics of e + e - pairs created in collisions with nuclear targets at intermediate and relativistic energies. Arising due to general spin and angular momentum constraints, the dilepton anisotropy seems to be quite sensitive to the contribution of different sources and may be used for disentangling these sources (or models) as well as an additional signature of a possible chiral symmetry restoration and phase transition of hadrons into the quark-gluon plasma. An anisotropy estimate for some dilepton sources is given and its relevance to the problems mentioned is discussed

  15. Anisotropy of the Topopah Spring Member Tuff

    Energy Technology Data Exchange (ETDEWEB)

    Martin, R.J. III; Boyd, P.J.; Haupt, R.W. [New England Research, Inc., White River Junction, VT (United States); Price, R.H. [Sandia National Labs., Albuquerque, NM (United States)

    1992-07-01

    Mechanical properties of the tuffaceous rocks within Yucca Mountain are needed for near and far-field modeling of the potential nuclear waste repository. If the mechanical properties are significantly anisotropic (i.e., direction-dependent), a more complex model is required. Relevant data from tuffs tested in earlier studies indicate that elastic and strength properties are anisotropic. This scoping study confirms the elastic anisotropy and concludes some tuffs are transversely isotropic. An approach for sampling and testing the rock to determine the magnitude of the anisotropy is proposed.

  16. COSMIC-RAY SMALL-SCALE ANISOTROPIES AND LOCAL TURBULENT MAGNETIC FIELDS

    Energy Technology Data Exchange (ETDEWEB)

    López-Barquero, V. [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); Farber, R. [Department of Physics and Astronomy, Wheaton College, Norton, MA 02766 (United States); Xu, S. [Department of Astronomy, School of Physics, Peking University, Beijing 100871 (China); Desiati, P. [Wisconsin IceCube Particle Astrophysics Center (WIPAC), University of Wisconsin, Madison, WI 53703 (United States); Lazarian, A. [Department of Astronomy, University of Wisconsin, Madison, WI 53706 (United States)

    2016-10-10

    Cosmic-ray anisotropy has been observed in a wide energy range and at different angular scales by a variety of experiments over the past decade. However, no comprehensive or satisfactory explanation has been put forth to date. The arrival distribution of cosmic rays at Earth is the convolution of the distribution of their sources and of the effects of geometry and properties of the magnetic field through which particles propagate. It is generally believed that the anisotropy topology at the largest angular scale is adiabatically shaped by diffusion in the structured interstellar magnetic field. On the contrary, the medium- and small-scale angular structure could be an effect of nondiffusive propagation of cosmic rays in perturbed magnetic fields. In particular, a possible explanation for the observed small-scale anisotropy observed at the TeV energy scale may be the effect of particle propagation in turbulent magnetized plasmas. We perform numerical integration of test particle trajectories in low- β compressible magnetohydrodynamic turbulence to study how the cosmic rays’ arrival direction distribution is perturbed when they stream along the local turbulent magnetic field. We utilize Liouville’s theorem for obtaining the anisotropy at Earth and provide the theoretical framework for the application of the theorem in the specific case of cosmic-ray arrival distribution. In this work, we discuss the effects on the anisotropy arising from propagation in this inhomogeneous and turbulent interstellar magnetic field.

  17. Van Allen Probes Observations of Magnetic Field Dipolarization and Its Associated O+ Flux Variations in the Inner Magnetosphere at L 6.6

    Science.gov (United States)

    Nose, M.; Keika, K.; Kletzing, C. A.; Spence, H. E.; Smith, C. W.; MacDowall, R. J.; Reeves, G. D.; Larsen, B. A.; Mitchell, D. G.

    2016-01-01

    We investigate the magnetic field dipolarization in the inner magnetosphere and its associated ion flux variations, using the magnetic field and energetic ion flux data acquired by the Van Allen Probes. From a study of 74 events that appeared at L= 4.5-6.6 between 1 October 2012 and 31 October 2013, we reveal the following characteristics of the dipolarization in the inner magnetosphere: (1) its time scale is approximately 5 min; (2) it is accompanied by strong magnetic fluctuations that have a dominant frequency close to the O+ gyrofrequency; (3) ion fluxes at 20-50 keV are simultaneously enhanced with larger magnitudes for O+ than for H+; (4) after a few minutes of the dipolarization, the flux enhancement at 0.1-5 keV appears with a clear energy-dispersion signature only for O+; and (5) the energy-dispersed O+ flux enhancement appears in directions parallel or antiparallel to the magnetic field. From these characteristics, we discuss possible mechanisms that can provide selective acceleration to O+ ions at > 20 keV. We conclude that O+ ions at L= 5.4-6.6 undergo nonadiabatic local acceleration caused by oscillating electric field associated with the magnetic fluctuations and/or adiabatic convective transport from the plasma sheet to the inner magnetosphere by the impulsive electric field. At L= 4.5-5.4, however, only the former acceleration is plausible. We also conclude that the field-aligned energy-dispersed O+ ions at 0.1-5 keV originate from the ionosphere and are extracted nearly simultaneously to the onset of the dipolarization.

  18. Seismic anisotropy in central North Anatolian Fault Zone and its implications on crustal deformation

    Science.gov (United States)

    Licciardi, A.; Eken, T.; Taymaz, T.; Piana Agostinetti, N.; Yolsal-Çevikbilen, S.

    2018-04-01

    We investigate the crustal seismic structure and anisotropy around the central portion of the North Anatolian Fault Zone, a major plate boundary, using receiver function analysis. The characterization of crustal seismic anisotropy plays a key role in our understanding of present and past deformation processes at plate boundaries. The development of seismic anisotropy in the crust arises from the response of the rocks to complicated deformation regimes induced by plate interaction. Through the analysis of azimuthally-varying signals of teleseismic receiver functions, we map the anisotropic properties of the crust as a function of depth, by employing the harmonic decomposition technique. Although the Moho is located at a depth of about 40 km, with no major offset across the area, our results show a clear asymmetric distribution of crustal properties between the northern and southern blocks, divided by the North Anatolian Fault Zone. Heterogeneous and strongly anisotropic crust is present in the southern block, where complex intra-crustal signals are the results of strong deformation. In the north, a simpler and weakly anisotropic crust is typically observed. The strongest anisotropic signal is located in the first 15 km of the crust and is widespread in the southern block. Stations located on top of the main active faults in the area indicate the highest amplitudes, together with fault-parallel strikes of the fast plane of anisotropy. We interpret the origin of this signal as due to structure-induced anisotropy, and roughly determine its depth extent up to 15-20 km for these stations. Away from the faults, we suggest the contribution of previously documented uplifted basement blocks to explain the observed anisotropy at upper and middle crustal depths. Finally, we interpret coherent NE-SW orientations below the Moho as a result of frozen-in anisotropy in the upper mantle, as suggested by previous studies.

  19. CI, [CII] and CO observations towards TNJ 1338–1942: Probing the ISM in a massive proto-cluster galaxy at z = 4.11

    DEFF Research Database (Denmark)

    König, S; Greve, T R; Seymour, N

    2012-01-01

    density, temperature, ambient UV-field) prevailing in the interstellar medium (ISM) of these objects. Here we report on ongoing CI, [CII] and CO observations of TNJ 1338–1942 at z = 4.11 with the IRAM 30m telescope, the JCMT and ATCA. With these observations we will make a first attempt at constraining...... the average ISM conditions in TNJ 1338–1942....

  20. Steady-state acceptor fluorescence anisotropy imaging under evanescent excitation for visualisation of FRET at the plasma membrane.

    Directory of Open Access Journals (Sweden)

    Viviane Devauges

    Full Text Available We present a novel imaging system combining total internal reflection fluorescence (TIRF microscopy with measurement of steady-state acceptor fluorescence anisotropy in order to perform live cell Förster Resonance Energy Transfer (FRET imaging at the plasma membrane. We compare directly the imaging performance of fluorescence anisotropy resolved TIRF with epifluorescence illumination. The use of high numerical aperture objective for TIRF required correction for induced depolarization factors. This arrangement enabled visualisation of conformational changes of a Raichu-Cdc42 FRET biosensor by measurement of intramolecular FRET between eGFP and mRFP1. Higher activity of the probe was found at the cell plasma membrane compared to intracellularly. Imaging fluorescence anisotropy in TIRF allowed clear differentiation of the Raichu-Cdc42 biosensor from negative control mutants. Finally, inhibition of Cdc42 was imaged dynamically in live cells, where we show temporal changes of the activity of the Raichu-Cdc42 biosensor.

  1. Magnetocrystalline anisotropy of cementite pseudo single crystal fabricated under a rotating magnetic field

    Science.gov (United States)

    Yamamoto, Sukeyoshi; Terai, Tomoyuki; Fukuda, Takashi; Sato, Kazunori; Kakeshita, Tomoyuki; Horii, Shigeru; Ito, Mikio; Yonemura, Mitsuharu

    2018-04-01

    We have fabricated a pseudo single crystal of cementite under a rotating magnetic field and investigated its easy and hard axes of magnetization, and determined its magnetocrystalline anisotropy energy. The obtained results are as follows: the hard and easy axes of cementite are the a- and c-axes of the orthorhombic structure with the space group Pnma, respectively. The hard axis observed experimentally was in good agreement with that obtained by an ab initio calculation; however, such consistency was not observed for the easy axis. The magnetocrystalline anisotropy energy was determined as 334 ± 20 kJ/m3 at 5 K.

  2. Anisotropy indices and the effects on the hydric behaviour of natural stone

    Science.gov (United States)

    Fort, Rafael; Alvarez de Buergo, Monica; Varas, Maria Jose; Gomez-Heras, Miguel

    2010-05-01

    anisotropy are those with the highest capillarity coefficient. It can also be observed that for each petrological variety, this capillarity coefficient is higher in the specimens classified as a high level anisotropy class. At the same time, when capillary water is absorbed along the direction perpendicular to the anisotropic planes, the absorption capacity diminishes, no matter the anisotropy level of the stone is. On the contrary, capillary coefficients are higher when measurements are performed in a parallel direction to that of the greatest anisotropy of the stone specimen, where absorption tends to be faster with higher coefficients according to the porosity size and its geometry. These increments are more significant in the stone varieties in which anisotropy is mainly due to fissuring or schistosity planes, or related to stromatolitic planes or oriented minerals accumulation. The arrangement and placing of rocks used as building materials with a significant anisotropy will highly condition the durability and lifetime of a considered element. For that reason, is essential to determine anisotropy indices to obtain the best and most adequate arrangement of stone elements in building works, minimizing water entry and thus, the material decay. Acknowledgements: to both MATERNAS (0505/MAT/0094) and GEOMATERIALES (2009-1629) research programmes, funded by the Regional Government of Madrid; to the CONSOLIDER-INGENIO programme (CSD2007-0058), funded by the Spanish Ministry of Education and Science; and to the Spanish Geological and Mining Institute (IGME) for the specimens preparation and hydric behaviour measurements.

  3. Measurements of the cosmic-ray electron and positron spectrum and anisotropies with the Fermi LAT

    Science.gov (United States)

    Loparco, F.; Fermi LAT Collaboration

    2017-12-01

    The Large Area Telescope (LAT) onboard the Fermi satellite is a pair-conversion telescope for high-energy gamma rays of astrophysical origin. Although it was designed to be a high-sensitivity gamma-ray telescope, the LAT has proved to be an excellent electron/positron detector. It has been operating in low Earth orbit since June 2008 and has collected more than 16 million cosmic-ray electron and positron (CRE) events in its first seven years of operation. The huge data sample collected by the LAT enables a precise measurement of the CRE energy spectrum up to the TeV region. A search for anisotropies in the arrival directions of CREs was also performed. The upper limits on the dipole anisotropy probe the presence of nearby young and middle-aged CRE sources.

  4. Origin of Perpendicular Magnetic Anisotropy and Large Orbital Moment in Fe Atoms on MgO

    Science.gov (United States)

    Baumann, S.; Donati, F.; Stepanow, S.; Rusponi, S.; Paul, W.; Gangopadhyay, S.; Rau, I. G.; Pacchioni, G. E.; Gragnaniello, L.; Pivetta, M.; Dreiser, J.; Piamonteze, C.; Lutz, C. P.; Macfarlane, R. M.; Jones, B. A.; Gambardella, P.; Heinrich, A. J.; Brune, H.

    2015-12-01

    We report on the magnetic properties of individual Fe atoms deposited on MgO(100) thin films probed by x-ray magnetic circular dichroism and scanning tunneling spectroscopy. We show that the Fe atoms have strong perpendicular magnetic anisotropy with a zero-field splitting of 14.0 ±0.3 meV /atom . This is a factor of 10 larger than the interface anisotropy of epitaxial Fe layers on MgO and the largest value reported for Fe atoms adsorbed on surfaces. The interplay between the ligand field at the O adsorption sites and spin-orbit coupling is analyzed by density functional theory and multiplet calculations, providing a comprehensive model of the magnetic properties of Fe atoms in a low-symmetry bonding environment.

  5. Optical anisotropy of polyimide and polymethacrylate containing photocrosslinkable chalcone group in the side chain under irradiation of a linearly polarized UV light

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Dong Hoon; Cha, Young Kwan [Kyunghee Univ., Yongin (Korea, Republic of)

    2002-03-01

    Photocrosslinkable soluble polyimide and polymethacrylate compound were synthesized for studying the optically induced anisotropy of the thin films. Chalcone group was introduced into the side chain unit of two polymers. We observed a photodimerization behavior between the double bonds in the chalcone group and an optical anisotropy of these materials by irradiation of a linearly polarized UV light (LPL). Optical anisotropy of the thin film was also investigated by using polarized UV absorption spectroscopy.The dynamic property of optical anisotropy in photoreactive polyimide was compared to that in polymethacrylate containing chalcone group in the side chain.

  6. Optical anisotropy of polyimide and polymethacrylate containing photocrosslinkable chalcone group in the side chain under irradiation of a linearly polarized UV light

    CERN Document Server

    Choi, D H

    2002-01-01

    Photocrosslinkable soluble polyimide and polymethacrylate compound were synthesized for studying the optically induced anisotropy of the thin films. Chalcone group was introduced into the side chain unit of two polymers. We observed a photodimerization behavior between the double bonds in the chalcone group and an optical anisotropy of these materials by irradiation of a linearly polarized UV light (LPL). Optical anisotropy of the thin film was also investigated by using polarized UV absorption spectroscopy.The dynamic property of optical anisotropy in photoreactive polyimide was compared to that in polymethacrylate containing chalcone group in the side chain.

  7. Particle physics implications of Wilkinson microwave anisotropy ...

    Indian Academy of Sciences (India)

    1016 GeV) inflation. Keywords. Cosmic microwave background radiation; inflation; Wilkinson microwave anisotropy project. PACS Nos 98.80.-k; 98.80.Cq; 98.80.Es; 95.30.Cq; 12.10.Dm; 12.60.Jv. 1. Introduction. This review [1] is divided into ...

  8. Magnetic anisotropy in rare-earth metals

    DEFF Research Database (Denmark)

    Nielsen, Mourits; Bjerrum Møller, Hans; Lindgård, Per-Anker

    1970-01-01

    The magnetic field dependence of the energy of long- wavelength magnons in Tb-10%Ho has been studied by inelastic neutron scattering. The results agree with the `frozen-lattice' model, provided that the second-order magnetoelastic effect is taken into account. The planar anisotropy is almost...

  9. Pseudospin anisotropy classification of quantum Hall ferromagnets

    Czech Academy of Sciences Publication Activity Database

    Jungwirth, Tomáš; MacDonald, A. H.

    2000-01-01

    Roč. 63, č. 3 (2000), s. 035305-1 - 035305-9 ISSN 0163-1829 R&D Projects: GA ČR GA202/98/0085 Institutional research plan: CEZ:AV0Z1010914 Keywords : quantum Hall ferromagnets * anisotropy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.065, year: 2000

  10. Empirical evidence for inertial mass anisotropy

    International Nuclear Information System (INIS)

    Heller, M.; Siemieniec, G.

    1985-01-01

    A several attempts at measuring the possible deviations from inertial mass isotropy caused by a non-uniform distribution of matter are reviewed. A simple model of the inertial mass anisotropy and the results of the currently performed measurements concerning this effect are presented. 34 refs. (author)

  11. Acoustic axes in weak triclinic anisotropy

    Czech Academy of Sciences Publication Activity Database

    Vavryčuk, Václav

    2005-01-01

    Roč. 163, č. 2 (2005), s. 629-638 ISSN 0956-540X R&D Projects: GA AV ČR IAA3012309 Institutional research plan: CEZ:AV0Z30120515 Keywords : elastic-wave theory * perturbation methods * seismic anisotropy Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 1.826, year: 2005

  12. Effective anisotropy through traveltime and amplitude matching

    KAUST Repository

    Wang, Hui

    2014-08-05

    Introducing anisotropy to seismic wave propagation reveals more realistic physics of our Earth\\'s subsurface as compared to the isotropic assumption. However wavefield modeling, the engine of seismic inverse problems, in anisotropic media still suffers from computational burdens, in particular with complex anisotropy such as transversely isotropic (TI) and Orthorhombic anisotropy. We develop effective isotropic velocity and density models to package the effects of anisotropy such that the wave propagation behavior using these effective models approximate those of the original anisotropic model. We build these effective models through the high frequency asymptotic approximation based on the eikonal and transport equations. We match the geometrical behavior of the wave-fields, given by traveltimes, from the anisotropic and isotropic eikonal equations. This matching yields the effective isotropic velocity that approximates the kinematics of the anisotropic wavefield. Equivalently, we calculate the effective densities by equating the anisotropic and isotropic transport equations. The effective velocities and densities are then fed into the isotropic acoustic variable density wave equation to obtain cheaper anisotropic wavefields. We justify our approach by testing it on an elliptical anisotropic model. The numerical results demonstrate a good matching of both traveltime and amplitude between anisotropic and effective isotropic wavefields.

  13. Particle physics implications of Wilkinson microwave anisotropy ...

    Indian Academy of Sciences (India)

    microwave anisotropy project measurements. U A YAJNIK. Indian Institute of Technology Bombay, Mumbai 400 076, India. E-mail: yajnik@phy.iitb.ac.in. Abstract. We present an overview of the implications of the WMAP data for particle physics. The standard parameter set ϵ, η and ξ characterising the inflaton potential can.

  14. Azimuthal anisotropy of jet quenching at LHC

    Indian Academy of Sciences (India)

    Abstract. We analyze the azimuthal anisotropy of jet spectra due to energy loss of hard partons in quark–gluon plasma, created initially in nuclear overlap zone in collisions with non-zero impact parameter. The calculations are performed for semi-central Pb–Pb collisions at LHC energy.

  15. What we learn from CMB Anisotropies

    CERN Multimedia

    CERN. Geneva

    2007-01-01

    George Smoot shared the 2006 Nobel Prize with John Mathere for the discovery of the fluctuations of the cosmic microwave background. In this talk (which will not be the same as the Nobel lecture), he will discuss what we have learned about the universe in the recent past from these anisotropies.

  16. Anisotropy of Wood in the Microwave Region

    Science.gov (United States)

    Ziherl, Sasa; Bajc, Jurij; Urankar, Bernarda; Cepic, Mojca

    2010-01-01

    Wood is transparent for microwaves and due to its anisotropic structure has anisotropic dielectric properties. A laboratory experiment that allows for the qualitative demonstration and quantitative measurements of linear dichroism and birefringence in the microwave region is presented. As the proposed experiments are based on the anisotropy (of…

  17. Cosmology with cosmic microwave background anisotropy

    Indian Academy of Sciences (India)

    Measurements of CMB anisotropy and, more recently, polarization have played a very important role in allowing precise determination of various parameters of the `standard' cosmological model. The expectation of the paradigm of inflation and the generic prediction of the simplest realization of inflationary scenario in the ...

  18. Design of the detector to observe the energetic charged particles: a part of the solar X-ray spectrophotometer ChemiX onboard Interhelio-Probe mission

    Science.gov (United States)

    Dudnik, Oleksiy; Sylwester, Janusz; Kowalinski, Miroslaw; Bakala, Jaroslaw; Siarkowski, Marek; Evgen Kurbatov, mgr..

    2016-07-01

    Cosmic particle radiation may damages payload's electronics, optics, and sensors during of long-term scientific space mission especially the interplanetary ones. That is why it's extremely important to prevent failures of digital electronics, CCDs, semiconductor detectors at the times of passing through regions of enhanced charged particle fluxes. Well developed models of the Earth's radiation belts allow to predict and to protect sensitive equipment against disastrous influence of radiation due to energetic particle contained in the Van Allen belts. In the contrary interplanetary probes flying far away from our planet undergoes passages through clouds of plasma and solar cosmic rays not predictable by present models. Especially these concerns missions planned for non-ecliptic orbits. The practical approach to protect sensitive modules may be to measure the in situ particle fluxes with high time resolution and generation of alarm flags, which will switch off sensitive units of particular scientific equipment. The ChemiX (Chemical composition in X-rays) instrument is being developed by the Solar Physics Division of Polish Space Research Centre for the Interhelio-Probe interplanetary mission. Charged particle bursts can badly affect the regular measurements of X-ray spectra of solar origin. In order to detect presence of these enhanced particle fluxes the Background Particle Monitor (BPM) was developed constituting now a vital part of ChemiX. The BPM measurements of particle fluxes will assist to determine level of X-ray spectra contamination. Simultaneously BPM will measure the energy spectra of ambient particles. We present overall structure, design, technical and a scientific characteristic of BPM, particle sorts, and energy ranges to be registered. We describe nearly autonomous modular structure of BPM consisting of detector head, analogue and digital electronics modules, and of module of secondary power supply [1-3]. Detector head consists of three

  19. Shaping the solar wind electron temperature anisotropy by the interplay of core and suprathermal populations

    Science.gov (United States)

    Shaaban Hamd, S. M.; Lazar, M.; Poedts, S.; Pierrard, V.; Štverák

    2017-12-01

    We present the results of an advanced parametrization of the temperature anisotropy of electrons in the slow solar wind and the electromagnetic instabilities resulting from the interplay of their thermal core and suprathermal halo populations. A large set of observational data (from the Ulysses, Helios and Cluster missions) is used to parametrize these components and establish their correlations. Comparative analysis demonstrates for the first time a particular implication of the suprathermal electrons which are less dense but hotter than thermal electrons. The instabilities are significantly stimulated by the interplay of the core and halo populations, leading to lower thresholds which shape the observed limits of the temperature anisotropy for both the core and halo populations. This double agreement strongly suggests that the selfgenerated instabilities play the major role in constraining the electron anisotropy.

  20. Computing magnetic anisotropy constants of single molecule magnets

    Indian Academy of Sciences (India)

    Administrator

    stringent requirements for a molecule to behave as a. SMM. Modelling magnetic anisotropy in these sys- tems becomes necessary for developing new SMMs with desired properties. Magnetic anisotropy of SMMs is computed by treating the anisotropy Hamiltonian as a perturbation over the Heisenberg exchange ...

  1. Measuring the Alfvénic nature of the interstellar medium: Velocity anisotropy revisited

    International Nuclear Information System (INIS)

    Burkhart, Blakesley; Lazarian, A.; Leão, I. C.; De Medeiros, J. R.; Esquivel, A.

    2014-01-01

    The dynamics of the interstellar medium (ISM) are strongly affected by turbulence, which shows increased anisotropy in the presence of a magnetic field. We expand upon the Esquivel and Lazarian method to estimate the Alfvén Mach number using the structure function anisotropy in velocity centroid data from Position-Position-Velocity maps. We utilize three-dimensional magnetohydrodynamic simulations of fully developed turbulence, with a large range of sonic and Alfvénic Mach numbers, to produce synthetic observations of velocity centroids with observational characteristics such as thermal broadening, cloud boundaries, noise, and radiative transfer effects of carbon monoxide. In addition, we investigate how the resulting anisotropy-Alfvén Mach number dependency found in Esquivel and Lazarian might change when taking the second moment of the Position-Position-Velocity cube or when using different expressions to calculate the velocity centroids. We find that the degree of anisotropy is related primarily to the magnetic field strength (i.e., Alfvén Mach number) and the line-of-sight orientation, with a secondary effect on sonic Mach number. If the line of sight is parallel to up to ≈45 deg off of the mean field direction, the velocity centroid anisotropy is not prominent enough to distinguish different Alfvénic regimes. The observed anisotropy is not strongly affected by including radiative transfer, although future studies should include additional tests for opacity effects. These results open up the possibility of studying the magnetic nature of the ISM using statistical methods in addition to existing observational techniques.

  2. Report on 1985 research result on the R and D of observation system for probing resources. 2/4; 1985 nendo shigen tansayo kansoku system no kenkyu kaihatsu. 2/4

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1986-03-01

    This paper explains the result of R and D of the observation system for probing resources in fiscal 1985. Concerning the interface with the satellite body in the system design and control, the design was clarified for the exclusive use of the interface between an on-satellite synthetic-aperture radar and the satellite body, as were the conditions/specifications of the optical part, detector and signal processor of the sensor system, with the studies conducted for the purpose of switching over to the basic design of the following year without difficulty. Then, an examination was carried out for the basic design level of the interface between the satellite body and the transmitter of the mission. A detailed examination was made for the purpose of smoothing the interface between the mission transmitter of the earth resources satellite ERS-1 and the terrestrial station. In the operation mission analysis, an investigation was made into the efficient operation of on-satellite equipment, with studies made on the conditions and specifications of an on-satellite optical sensor. In the studies of the system design evaluation technology, picture quality of the optical sensor was examined, as were sensor specifications suitable for the probe of oil and other underground resources. In addition, aircraft/space shuttle experiment plans were also examined. (NEDO)

  3. Neutron is a marvelous probe to see the living things as it is alive. Real time and in-situ observation on living polymerization

    International Nuclear Information System (INIS)

    Koizumi, Satoshi

    2011-01-01

    Small-angle neutron scattering was employed in order to perform a real time and in-situ observation on a polymerization-induced self-assembly process in in-vivo or in-vitro systems; precise living anionic polymerization of poly-styrene-b-polyisoprene, pre-irradiation radical polymerization of polystyrene onto a polytetrafluoroethylene film, and microbial or enzymatic polymerization of cellulose. The aim of these studies is to clarify self-organizations of macro-molecular assemblies appeared in open non-equilibrium systems, which are exposed to external energy and mass flows induced by chemical reactions. The open non-equilibrium systems are believed to be important for understanding pattern formations not only in materials processing in industry but also in living things. Small-angle scattering observed for the systems was investigated according to the methods established for condensed matter physics (fractal and computational analyses), bridging with synthetic chemistry and molecular biology. (author)

  4. Probing viscoelastic surfaces with bimodal tapping-mode atomic force microscopy: Underlying physics and observables for a standard linear solid model.

    Science.gov (United States)

    Solares, Santiago D

    2014-01-01

    This paper presents computational simulations of single-mode and bimodal atomic force microscopy (AFM) with particular focus on the viscoelastic interactions occurring during tip-sample impact. The surface is modeled by using a standard linear solid model, which is the simplest system that can reproduce creep compliance and stress relaxation, which are fundamental behaviors exhibited by viscoelastic surfaces. The relaxation of the surface in combination with the complexities of bimodal tip-sample impacts gives rise to unique dynamic behaviors that have important consequences with regards to the acquisition of quantitative relationships between the sample properties and the AFM observables. The physics of the tip-sample interactions and its effect on the observables are illustrated and discussed, and a brief research outlook on viscoelasticity measurement with intermittent-contact AFM is provided.

  5. Proximal Probes Facility

    Data.gov (United States)

    Federal Laboratory Consortium — The Proximal Probes Facility consists of laboratories for microscopy, spectroscopy, and probing of nanostructured materials and their functional properties. At the...

  6. Magnetic anisotropy in GaMnAs; Magnetische Anisotropie in GaMnAs

    Energy Technology Data Exchange (ETDEWEB)

    Daeubler, Joachim

    2009-07-02

    The goal of the present work was the detailed investigation of the impact of parameters like vertical strain, hole concentration, substrate orientation and patterning on the MA in GaMnAs. At first a method is introduced enabling us to determine the MA from angle-dependent magnetotransport measurements. This method was used to analyze the impact of vertical strain {epsilon}{sub zz} on the MA in a series of GaMnAs layers with a Mn content of 5% grown on relaxed InGaAs-templates. While hole concentration and Curie temperature were found to be unaffected by vertical strain, a significant dependence of the MA on {epsilon}{sub zz} was found. The most pronounced dependence was observed for the anisotropy parameter B{sub 2} {sub perpendicular} {sub to}, representing the intrinsic contribution to the MA perpendicular to the layer plane. For this parameter a linear dependence on {epsilon}{sub zz} was found, resulting in a strain-induced transition of the magnetic easy axis with increasing strain from in-plane to out-of-plane at {epsilon}{sub zz} {approx} -0.13%. Post-growth annealing of the samples leads to an outdiffusion and/or regrouping of the highly mobile Mn interstitial donor defects, resulting in an increase in both p and T{sub C}. For the annealed samples, the transition from in-plane to out-of-plane easy axis takes place at {epsilon}{sub zz} {approx} -0.07%. From a comparison of as-grown and annealed samples, B{sub 2} {sub perpendicular} {sub to} was found to be proportional to both p and {epsilon}{sub zz}, B{sub 2} {sub perpendicular} {sub to} {proportional_to} p .{epsilon}{sub zz}. To study the influence of substrate orientation on the magnetic properties of GaMnAs, a series of GaMnAs layers with Mn contents up to 5% was grown on (001)- and (113)A-oriented GaAs substrates. The hole densities and Curie temperatures, determined from magnetotransport measurements, are drastically reduced in the (113)A layers. The differences in the magnetic properties of (113)A- and

  7. Theory of the in-plane anisotropy of magnetic excitations in YBa2Cu3O6+y

    International Nuclear Information System (INIS)

    Yamase, Hiroyuki; Metzner, Walter

    2007-01-01

    A pronounced xy-anisotropy was observed in recent neutron scattering experiments for magnetic excitations in untwinned YBa 2 Cu 3 O 6+y (YBCO). The small anisotropy of the bare band structure due to the orthorhombic crystal symmetry seems to be enhanced by correlation effects. A natural possibility is that the system is close to a Pomeranchuk instability associated with a d-wave Fermi surface deformation (dFSD). We investigate this possibility in the bilayer t-J model within a self-consistent slave-boson mean-field theory. We show that the dFSD correlations drive a pronounced xy-anisotropy of magnetic excitations at low doping and at relatively high temperatures, providing a scenario for the observed xy-anisotropy in optimally doped as well as underdoped YBCO, including the pseudogap phase

  8. Increased anisotropy in neonatal meningitis: an indicator of meningeal inflammation

    Energy Technology Data Exchange (ETDEWEB)

    Trivedi, Richa; Gupta, Rakesh K.; Nath, Kavindra [Sanjay Gandhi Post Graduate Institute of Medical Sciences, Department of Radiodiagnosis, Lucknow, UP (India); Malik, Gyanendra K.; Gupta, Amit [King George' s Medical University, Department of Pediatrics, Lucknow (India); Prasad, Kashi N. [Sanjay Gandhi Postgraduate Institute of Medical Sciences, Department of Microbiology, Lucknow (India); Purwar, Ankur; Rathore, Divya; Rathore, Ram K.S. [Indian Institute of Technology, Department of Mathematics, Kanpur (India); Narayana, Ponnada A. [University of Texas Medical School at Houston, Department of Diagnostic and Interventional Imaging, Houston, TX (United States)

    2007-09-15

    Increased anisotropy in brain abscesses has been shown to be due to adhesion of inflammatory cells and is suggestive of an active inflammatory process. The objective of this study was to determine if similar changes occur in the pia-arachnoid on the surface of the cerebral cortex in patients with pyogenic meningitis, and if these changes regress following antibiotic therapy. Diffusion tensor imaging (DTI) was performed on 14 term neonates (mean age 13 days) with bacterial meningitis and 10 healthy age- and sex-matched controls. Regions of interest (ROIs) were placed on areas including the leptomeninges, the cerebral cortex and adjoining subcortical white matter for quantitation of mean fractional anisotropy (FA) and diffusivity (MD) values. Follow-up MRI was performed in five of the neonates in the patient group after 2 weeks of antibiotic treatment. FA and MD values were compared in patients before and after antibiotic treatment as well as with those in the healthy controls. Significantly higher FA values but no difference in MD values were observed in the patient group as compared to the healthy controls at both time points (before and after antibiotic treatment). Significantly decreased FA values in the frontal, occipital and temporal cortical regions were observed in patients following antibiotic treatment. DTI-derived FA may be of value in the noninvasive assessment of meningeal inflammatory activity and treatment response in neonates. (orig.)

  9. Magnetic anisotropy and anisotropic ballistic conductance of thin magnetic wires

    International Nuclear Information System (INIS)

    Sabirianov, R.

    2006-01-01

    The magnetocrystalline anisotropy of thin magnetic wires of iron and cobalt is quite different from the bulk phases. The spin moment of monatomic Fe wire may be as high as 3.4 μ B , while the orbital moment as high as 0.5 μ B . The magnetocrystalline anisotropy energy (MAE) was calculated for wires up to 0.6 nm in diameter starting from monatomic wire and adding consecutive shells for thicker wires. I observe that Fe wires exhibit the change sign with the stress applied along the wire. It means that easy axis may change from the direction along the wire to perpendicular to the wire. We find that ballistic conductance of the wire depends on the direction of the applied magnetic field, i.e. shows anisotropic ballistic magnetoresistance. This effect occurs due to the symmetry dependence of the splitting of degenerate bands in the applied field which changes the number of bands crossing the Fermi level. We find that the ballistic conductance changes with applied stress. Even for thicker wires the ballistic conductance changes by factor 2 on moderate tensile stain in our 5x4 model wire. Thus, the ballistic conductance of magnetic wires changes in the applied field due to the magnetostriction. This effect can be observed as large anisotropic BMR in the experiment

  10. Increased anisotropy in neonatal meningitis: an indicator of meningeal inflammation

    International Nuclear Information System (INIS)

    Trivedi, Richa; Gupta, Rakesh K.; Nath, Kavindra; Malik, Gyanendra K.; Gupta, Amit; Prasad, Kashi N.; Purwar, Ankur; Rathore, Divya; Rathore, Ram K.S.; Narayana, Ponnada A.

    2007-01-01

    Increased anisotropy in brain abscesses has been shown to be due to adhesion of inflammatory cells and is suggestive of an active inflammatory process. The objective of this study was to determine if similar changes occur in the pia-arachnoid on the surface of the cerebral cortex in patients with pyogenic meningitis, and if these changes regress following antibiotic therapy. Diffusion tensor imaging (DTI) was performed on 14 term neonates (mean age 13 days) with bacterial meningitis and 10 healthy age- and sex-matched controls. Regions of interest (ROIs) were placed on areas including the leptomeninges, the cerebral cortex and adjoining subcortical white matter for quantitation of mean fractional anisotropy (FA) and diffusivity (MD) values. Follow-up MRI was performed in five of the neonates in the patient group after 2 weeks of antibiotic treatment. FA and MD values were compared in patients before and after antibiotic treatment as well as with those in the healthy controls. Significantly higher FA values but no difference in MD values were observed in the patient group as compared to the healthy controls at both time points (before and after antibiotic treatment). Significantly decreased FA values in the frontal, occipital and temporal cortical regions were observed in patients following antibiotic treatment. DTI-derived FA may be of value in the noninvasive assessment of meningeal inflammatory activity and treatment response in neonates. (orig.)

  11. Probing the cold and warm molecular gas in the Whirlpool Galaxy: Herschel SPIRE-FTS observations of the central region of M51 (NGC 5194)

    Science.gov (United States)

    Schirm, M. R. P.; Wilson, C. D.; Kamenetzky, J.; Parkin, T. J.; Glenn, J.; Maloney, P.; Rangwala, N.; Spinoglio, L.; Baes, M.; Boselli, A.; Cooray, A.; De Looze, I.; Fernández-Ontiveros, J. A.; Karczewski, O. Ł.; Wu, R.

    2017-10-01

    We present Herschel Spectral and Photometric Imaging Receiver (SPIRE)-Fourier Transform Spectrometer (FTS) intermediate-sampled mapping observations of the central ˜8 kpc (˜150 arcsec) of M51, with a spatial resolution of 40 arcsec. We detect four 12CO transitions (J = 4-3 to J = 7-6) and the [C I] 3P2-3P1 and 3P1-3P0 transitions. We supplement these observations with ground-based observations of 12CO J = 1-0 to J = 3-2 and perform a two-component non-local thermodynamic equilibrium analysis. We find that the molecular gas in the nucleus and centre regions has a cool component (Tkin ˜ 10-20 K) with a moderate but poorly constrained density (n(H2) ˜ 103-106 cm-3), as well as significant molecular gas in a warmer (Tkin ˜ 300-3000 K), lower density (n(H2) ˜ 101.6-102.5 cm-3) component. We compare our CO line ratios and calculated densities along with ratios of CO to total infrared luminosity to a grid of photon-dominated region (PDR) models and find that the cold molecular gas likely resides in PDRs with a field strength of G0 ˜ 102. The warm component likely requires an additional source of mechanical heating, from supernovae and stellar winds or possibly shocks produced in the strong spiral density wave. When compared to similar two-component models of other star-forming galaxies published as part of the Very Nearby Galaxies Survey (Arp 220, M82 and NGC 4038/39), M51 has the lowest density for the warm component, while having a warm gas mass fraction that is comparable to those of Arp 220 and M82, and significantly higher than that of NGC 4038/39.

  12. Van Allen probes, NOAA, GOES, and ground observations of an intense EMIC wave event extending over 12 h in magnetic local time

    OpenAIRE

    Engebretson, M. J.; Posch, J. L.; Wygant, J. R.; Kletzing, C. A.; Lessard, M. R.; Huang, C.-L.; Spence, H. E.; Smith, C. W.; Singer, H. J.; Omura, Y.; Horne, R. B.; Reeves, G. D.; Baker, D. N.; Gkioulidou, M.; Oksavik, K.

    2015-01-01

    Although most studies of the effects of EMIC waves on Earth's outer radiation belt have focused on events in the afternoon sector in the outer plasmasphere or plume region, strong magnetospheric compressions provide an additional stimulus for EMIC wave generation across a large range of local times and L shells. We present here observations of the effects of a wave event on February 23, 2014 that extended over 8 hours in UT and over 12 hours in local time, stimulated by a gradual 4-hour rise ...

  13. Effects of fluctuations and noise on the neutron monitor diurnal anisotropy. II. Non-field-aligned diffusion

    International Nuclear Information System (INIS)

    Owens, A.J.

    1977-01-01

    The effects of non-field-aligned diffusion (i.e., terms in the diffusion tensor proportional to the antisymmetric coefficient kappa/sub A/) on the observed day-to-day deviation of the diffusive diurnal anisotropy from the daily average magnetic field direction are considered. Using reasonable parameters for the diffusion of cosmic rays in interplanetary space, I show that these terms give a natural explanation for the angular difference between the anisotropy and field directions during normal quiet interplanetary epochs

  14. Probing stratospheric transport and chemistry with new balloon and aircraft observations of the meridional and vertical N2O isotope distribution

    Directory of Open Access Journals (Sweden)

    J. Kaiser

    2006-01-01

    Full Text Available A comprehensive set of stratospheric balloon and aircraft samples was analyzed for the position-dependent isotopic composition of nitrous oxide (N2O. Results for a total of 220 samples from between 1987 and 2003 are presented, nearly tripling the number of mass-spectrometric N2O isotope measurements in the stratosphere published to date. Cryogenic balloon samples were obtained at polar (Kiruna/Sweden, 68° N, mid-latitude (southern France, 44° N and tropical sites (Hyderabad/India, 18° N. Aircraft samples were collected with a newly-developed whole air sampler on board of the high-altitude aircraft M55 Geophysica during the EUPLEX 2003 campaign. For mixing ratios above 200 nmol mol−1, relative isotope enrichments (δ values and mixing ratios display a compact relationship, which is nearly independent of latitude and season and which can be explained equally well by Rayleigh fractionation or mixing. However, for mixing ratios below 200 nmol mol−1 this compact relationship gives way to meridional, seasonal and interannual variations. A comparison to a previously published mid-latitude balloon profile even shows large zonal variations, justifying the use of three-dimensional (3-D models for further data interpretation. In general, the magnitude of the apparent fractionation constants (i.e., apparent isotope effects increases continuously with altitude and decreases from the equator to the North Pole. Only the latter observation can be understood qualitatively by the interplay between the time-scales of N2O photochemistry and transport in a Rayleigh fractionation framework. Deviations from Rayleigh fractionation behavior also occur where polar vortex air mixes with nearly N2O-free upper stratospheric/mesospheric air (e.g., during the boreal winters of 2003 and possibly 1992. Aircraft observations in the polar vortex at mixing ratios below 200 nmol mol−1 deviate from isotope variations expected for both Rayleigh fractionation and two

  15. Variation in the strain anisotropy of Zircaloy with temperature and strain

    International Nuclear Information System (INIS)

    Hindle, E.D.; Worswick, D.

    1984-01-01

    The strong crystallographic texture which is developed during the fabrication of zirconium-based alloys causes pronounced anisotropy in their mechanical properties, particularly deformation. The tendency for circular-section tension specimens with a high concentration of basal poles in one direction to become elliptical when deformed in tension has been used in this study to provide quantitative data on the effects of both strain and temperature on strain anisotropy. Tension tests were carried out over a temperature range of 293 to 1193 K on specimens machined from Zircaloy-2 plate. The strain anisotropy was found to increase markedly at temperatures over 923 K, reaching a maximum in the region of 1070 K. The strain anisotropy increased with increasing strain in this temperature region. The study was extended to Zircaloy-4 pressurized-water reactor fuel cladding by carrying out tube swelling tests and evaluating the axial deformation produced. Although scatter in the test results was higher than that exhibited in the tension tests, the general trend in the data was similar. The effects of the strain anisotropy observed are discussed in relation to the effects of temperature on the ductility of Zircaloy fuel cladding tubes during postulated largebreak loss-of-coolant accidents

  16. Precision ESR Measurements of Transverse Anisotropy in the Single-molecule Magnet Ni4

    Science.gov (United States)

    Friedman, Jonathan; Collett, Charles; Allao Cassaro, Rafael

    We present a method to precisely determine the transverse anisotropy in a single-molecule magnet (SMM) through electron-spin resonance measurements of a tunnel splitting that arises from the anisotropy via first-order perturbation theory. We demonstrate the technique using the SMM Ni4 diluted via co-crystallization in a diamagnetic isostructural analogue. At 5% dilution, we find markedly narrower resonance peaks than are observed in undiluted samples. Ni4 has a zero-field tunnel splitting of 4 GHz, and we measure that transition at several nearby frequencies using custom loop-gap resonators, allowing a precise determination of the tunnel splitting. Because the transition under investigation arises due to a first-order perturbation from the transverse anisotropy, and lies at zero field, we can relate the splitting to the transverse anisotropy independent of any other Hamiltonian parameters. This method can be applied to other SMMs with zero-field tunnel splittings arising from first-order transverse anisotropy perturbations. NSF Grant No. DMR-1310135.

  17. Neutron anisotropy and X-ray production of the FN-II dense plasma focus device

    International Nuclear Information System (INIS)

    Castillo, F.; Herrera, J.J.E.; Rangel, J.; Alfaro, A.; Maza, M.A.; Sakaguchi, V.; Espinosa, G.; Golzarri, J.I.

    2002-01-01

    The FN-II Dense Plasma Focus is a small (< 5kJ ) Mather type device, where the dependence of neutron yield and its anisotropy, in terms of deuterium filling pressure, and the neutron emission angular distribution have been studied. Two different electrode configurations have been tested, showing that their geometry plays an important role both on neutron yield and anisotropy. Time integrated anisotropy has been measured with silver activation counters, on a shot to shot basis. CR-39 nuclear track detectors are used to determine the angular distribution of neutrons, averaged over tens of shots, showing that an isotropic pedestal accounts for 70% of the emission, while the anisotropy component accounts for the remaining 30%. The neutron yield shows a tendency to increase with anisotropy, as well as with the emission of hard X-rays observed on-axis. Scintillator- photomultiplier detectors show a slight Doppler shift in the neutron energy at backward angles, supporting the beam-target mechanism. Additional information has been obtained from time integrated X-ray diagnostics, which include filtered multi-pin-hole cameras. (author)

  18. Anisotropy of the Vortex Magnetic Field Distribution in LuNi2B2

    Science.gov (United States)

    Eskildsen, M. R.; Debeer-Schmitt, L.; Rovira, K.; Jenkins, N.; Dewhurst, C. D.; Bud'Ko, S. L.; Canfield, P. C.

    2008-03-01

    It is well known that the vortex lattice (VL) symmetry and orientation in type-II superconductors is very sensitive to any anisotropy within the screening current plane. A classic example is the sequence of transitions from hexagonal to rhombic to square symmetry, which was first observed in the borocarbide superconductors and explained by a Fermi surface anisotropy coupled with the non-local electrodynamics responsible for vortex-vortex interactions. Recently, however, this is mounting experimental evidence for a strong gap anisotropy and possible point nodes in the basal plane of these materials. Here we report on small-angle neutron scattering studies of the VL in a carefully annealed, high quality LuNi2B2C single crystal, which permitted us to measure the VL form factor for a large number of reflections. These measurements allow a reconstruction of the real space profile of the magnetic field around the vortices, reflecting the basal plane anisotropy of the screening currents in LuNi2B2C. The results will be compared to predictions for both Fermi surface and gap anisotropies, and will serve as a valuable reference for more complicated compounds as e.g. Sr2RuO4, heavy fermions and high-Tc's.

  19. Shear-Wave Splitting and Crustal Anisotropy in the Shillong-Mikir Plateau of Northeast India

    Science.gov (United States)

    Bora, Dipok K.; Hazarika, Devajit; Paul, Arpita; Borah, Kajaljyoti; Borgohain, Jayanta Madhab

    2018-01-01

    Seismic anisotropy of crust beneath the Shillong-Mikir Plateau and the surrounding regions of northeast India have been investigated with the help of splitting analysis of S-wave of local earthquakes. We estimate a total 83 pairs of splitting parameters ( Φ and δt) from 67 local shallow focus earthquakes (depth ≤ 32 km) recorded by the 10 broadband seismological stations operated in the study region. The results show delay times ranging from 0.02 to 0.2 s, which correspond to anisotropy up to 4%, suggesting significant strength of anisotropy in the study region. Fast polarization direction ( Φ) in the Shillong Plateau shows mostly NW-SE trend in the western part and NE-SW trend in the northern part. Φs near Kopili fault (KF) follows NW-SE trend. Φ at most of the stations in the study region is consistent with the local stress orientation, suggesting that the anisotropy is mainly caused by preferentially aligned cracks responding to the stress field. On the other hand, anisotropy observed near the KF is due to aligned macroscopic fracture related to strike-slip movement in the fault zone.

  20. Reduction of anisotropy influence and contacting effects in in-vitro bioimpedance measurements

    International Nuclear Information System (INIS)

    Guermazi, M; Kanoun, O; Derbel, N

    2013-01-01

    Experimental procedure is a decisive part in in-vitro bioimpedance measurement in order to get reproducible measurements. An electrode configuration is proposed to avoid several disadvantages produced by needle electrodes and circular non-penetrating electrode. The proposed electrode geometry reduces the influence of anisotropy and allows simultaneously a good probe contacting. We propose an experimental method to avoid the appearance of bacteria and to reduce water loss in meat during experiment post-mortem. The results show that electrode configuration with the developed experimental method have ensured reproducible measurements during a long period of 14 days post-mortem.

  1. Reduction of anisotropy influence and contacting effects in in-vitro bioimpedance measurements

    Science.gov (United States)

    Guermazi, M.; Kanoun, O.; Derbel, N.

    2013-04-01

    Experimental procedure is a decisive part in in-vitro bioimpedance measurement in order to get reproducible measurements. An electrode configuration is proposed to avoid several disadvantages produced by needle electrodes and circular non-penetrating electrode. The proposed electrode geometry reduces the influence of anisotropy and allows simultaneously a good probe contacting. We propose an experimental method to avoid the appearance of bacteria and to reduce water loss in meat during experiment post-mortem. The results show that electrode configuration with the developed experimental method have ensured reproducible measurements during a long period of 14 days post-mortem.

  2. Strain-induced fermi contour anisotropy of GaAs 2D holes.

    Science.gov (United States)

    Shabani, J; Shayegan, M; Winkler, R

    2008-03-07

    We report measurements of magnetoresistance commensurability peaks, induced by a square array of antidots, in GaAs (311)A two-dimensional holes as a function of applied in-plane strain. The data directly probe the shapes of the Fermi contours of the two spin subbands that are split thanks to the spin-orbit interaction and strain. The experimental results are in quantitative agreement with the predictions of accurate energy band calculations, and reveal that the majority spin subband has a severely distorted Fermi contour whose anisotropy can be tuned with strain.

  3. Evaluation of anisotropy of J c in silver-sheathed Bi-2223 tape

    International Nuclear Information System (INIS)

    Himeda, Y.; Kiuchi, M.; Otabe, E.S.; Matsushita, T.

    2005-01-01

    The magnetic field angle dependence of J c was measured by four probe method and DC magnetization method. The latter measurement was used for the specimen before and after bending to break the intergrain current in order to investigate only the intragrain current. It was found that the intragrain critical current density could be increased by a factor 2.7 in a parallel magnetic field when the c-axis misorientation could be improved. From the field angle dependence of the intragrain critical current density, the anisotropy parameter was estimated as 20.4

  4. Fourier descriptors analysis of anisotropy and preferred Orientation in geological samples

    International Nuclear Information System (INIS)

    Santiago Buey, C. de

    2011-01-01

    This study focuses on the use of Fourier descriptors to evaluate and quantify two specific fabric characteristics of geological materials: anisotropy of particles or voids morphologies and particle orientation. To this end, a theoretical section of a rock was created, made of ellipses and rectangles of different axes ratios and different orientations. The Fourier descriptors method was applied to calculate the anisotropy and orientation of each particle and, finally, a rose diagram was constructed to represent the particles orientations distribution and to observe the presence or not of any preferred orientation. (Author) 15 refs.

  5. Transport current anisotropy in oriented grained bulk YBa2Cu3O(x) superconductor

    International Nuclear Information System (INIS)

    Selvamanickam, V.; Salama, K.

    1990-01-01

    The anisotropy in transport current density has been studied on bulk YBa2Cu3O(x) superconductor. The transport current density measurements were performed on oriented grained YBa2Cu3O(x) superconductor with the current aligned at different angles to the a-b plane. The angular dependence of Jc shows a rapid drop when the transport current is misaligned from the a-b plane at small angles and then a slow decrease at higher angles. An anisotropy ratio of about 25 is observed at 77 K and zero field between the Jc along a-b plane and that perpendicular to the plane. 15 refs

  6. Transport current anisotropy in oriented grained bulk YBa2Cu3Ox superconductor

    International Nuclear Information System (INIS)

    Selvamanickam, V.; Salama, K.

    1990-01-01

    The anisotropy in transport current density has been studied on bulk YBa 2 Cu 3 O x superconductor. The transport current density measurements were performed on oriented grained YBa 2 Cu 3 O x superconductor with the current aligned at different angles to the a endash b plane. The angular dependence of J c shows a rapid drop when the transport current is misaligned from the a endash b plane at small angles and then a slow decrease at higher angles. An anisotropy ratio of about 25 is observed at 77 K and zero field between the J c along a endash b plane and that perpendicular to the plane

  7. Interfacial magnetic anisotropy of Co90Zr10 on Pt layer.

    Science.gov (United States)

    Kil, Joon Pyo; Bae, Gi Yeol; Suh, Dong Ik; Choi, Won Joon; Noh, Jae Sung; Park, Wanjun

    2014-11-01

    Spin Transfer Torque (STT) is of great interest in data writing scheme for the Magneto-resistive Random Access Memory (MRAM) using Magnetic Tunnel Junction (MTJ). Scalability for high density memory requires ferromagnetic electrodes having the perpendicular magnetic easy axis. We investigated CoZr as the ferromagnetic electrode. It is observed that interfacial magnetic anisotropy is preferred perpendicular to the plane with thickness dependence on the interfaces with Pt layer. The anisotropy energy (K(u)) with thickness dependence shows a change of magnetic-easy-axis direction from perpendicular to in-plane around 1.2 nm of CoZr. The interfacial anisotropy (K(i)) as the directly related parameters to switching and thermal stability, are estimated as 1.64 erg/cm2 from CoZr/Pt multilayered system.

  8. CeCo5 thin films with perpendicular anisotropy grown by molecular beam epitaxy

    Science.gov (United States)

    Sharma, S.; Hildebrandt, E.; Major, M.; Komissinskiy, P.; Radulov, I.; Alff, L.

    2018-04-01

    Buffer-free, highly textured (0 0 1) oriented CeCo5 thin films showing perpendicular magnetic anisotropy were synthesized on (0 0 1) Al2O3 substrates by molecular beam epitaxy. Ce exists in a mixture of Ce3+ and Ce4+ valence states as shown by X-ray photoelectron spectroscopy. The first anisotropy constant, K1, as measured by torque magnetometry was 0.82 MJ/m3 (8.2 ×106erg /cm3) . A maximum coercivity of 5.16 kOe with a negative temperature coefficient of -0.304%K-1 and a magnetization of 527.30 emu/cm3 was measured perpendicular to the film plane at 5 K. In addition, a large anisotropy of the magnetic moment of 15.5% was observed. These magnetic parameters make CeCo5 a potential candidate material for spintronic and magnetic recording applications.

  9. Small-scale microwave background anisotropies implied by large-scale data

    Science.gov (United States)

    Kashlinsky, A.

    1993-01-01

    In the absence of reheating microwave background radiation (MBR) anisotropies on arcminute scales depend uniquely on the amplitude and the coherence length of the primordial density fluctuations (PDFs). These can be determined from the recent data on galaxy correlations, xi(r), on linear scales (APM survey). We develop here expressions for the MBR angular correlation function, C(theta), on arcminute scales in terms of the power spectrum of PDFs and demonstrate their accuracy by comparing with detailed calculations of MBR anisotropies. We then show how to evaluate C(theta) directly in terms of the observed xi(r) and show that the APM data give information on the amplitude, C(O), and the coherence angle of MBR anisotropies on small scales.

  10. Oriented grain growth and modification of 'frozen anisotropy' in the lithospheric mantle

    Science.gov (United States)

    Boneh, Yuval; Wallis, David; Hansen, Lars N.; Krawczynski, Mike J.; Skemer, Philip

    2017-09-01

    Seismic anisotropy throughout the oceanic lithosphere is often assumed to be generated by fossilized texture formed during deformation at asthenospheric temperatures close to the ridge. Here we investigate the effect of high-temperature and high-pressure static annealing on the texture of previously deformed olivine aggregates to simulate residence of deformed peridotite in the lithosphere. Our experiments indicate that the orientation and magnitude of crystallographic preferred orientation (CPO) will evolve due to the preferential growth of grains with low dislocation densities. These observations suggest that texture and stored elastic strain energy promote a style of grain growth that modifies the CPO of a deformed aggregate. We demonstrate that these microstructural changes alter the orientation distributions and magnitudes of seismic wave velocities and anisotropy. Therefore, static annealing may complicate the inference of past deformation kinematics from seismic anisotropy in the lithosphere.

  11. Nanoparticle metrology standards based on the time-resolved fluorescence anisotropy of silica colloids

    Science.gov (United States)

    Apperson, Kathleen; Karolin, Jan; Martin, Robert W.; Birch, David J. S.

    2009-02-01

    We demonstrate nanoparticle size measurement using time-resolved fluorescence anisotropy decay in relation to establishing a nanometrology standard. The rotational correlation time equivalent to the isotropic Brownian rotation of a fluorescent 6-methoxyquinolinium dye attached to amorphous silica nanoparticles was determined in three different LUDOXLUDOX is a registered trademark of DuPont Corporation. colloids from the complex fluorescence anisotropy decay observed. Once competing depolarization and nanoparticle aggregation had been taken into account, good agreement was found of 4.0 ± 0.4 nm, 6.4 ± 0.5 nm and 11.0 ± 1.6 nm corresponding to the manufacturer's reported particle radii of 3.5 nm, 6 nm and 11 nm, for LUDOX SM30, AM30 and AS40 respectively. We describe the measurement science required for acquisition and interpretation of fluorescence anisotropy decay data in order to determine nanoparticle size while highlighting the limitations and useful range of measurement.

  12. Nanoparticle metrology standards based on the time-resolved fluorescence anisotropy of silica colloids

    International Nuclear Information System (INIS)

    Apperson, Kathleen; Karolin, Jan; Martin, Robert W; Birch, David J S

    2009-01-01

    We demonstrate nanoparticle size measurement using time-resolved fluorescence anisotropy decay in relation to establishing a nanometrology standard. The rotational correlation time equivalent to the isotropic Brownian rotation of a fluorescent 6-methoxyquinolinium dye attached to amorphous silica nanoparticles was determined in three different LUDOX colloids from the complex fluorescence anisotropy decay observed. Once competing depolarization and nanoparticle aggregation had been taken into account, good agreement was found of 4.0 ± 0.4 nm, 6.4 ± 0.5 nm and 11.0 ± 1.6 nm corresponding to the manufacturer's reported particle radii of 3.5 nm, 6 nm and 11 nm, for LUDOX SM30, AM30 and AS40 respectively. We describe the measurement science required for acquisition and interpretation of fluorescence anisotropy decay data in order to determine nanoparticle size while highlighting the limitations and useful range of measurement

  13. Mathematical modelling of anisotropy of illite-rich shale

    Science.gov (United States)

    Chesnokov, E.M.; Tiwary, D.K.; Bayuk, I.O.; Sparkman, M.A.; Brown, R.L.

    2009-01-01

    The estimation of illite-rich shale anisotropy to account for the alignment of clays and gas- or brine-filled cracks is presented via mathematical modelling. Such estimation requires analysis to interpret the dominance of one effect over another. This knowledge can help to evaluate the permeability in the unconventional reservoir, stress orientation, and the seal capacity for the conventional reservoir. Effective media modelling is used to predict the elastic properties of the illite-rich shale and to identify the dominant contributions to the shale anisotropy. We consider two principal reasons of the shale anisotropy: orientation of clay platelets and orientation of fluid-filled cracks. In reality, both of these two factors affect the shale anisotropy. The goal of this study is, first, to separately analyse the effect of these two factors to reveal the specific features in P- and S-wave velocity behaviour typical of each of the factors, and, then, consider a combined effect of the factors when the cracks are horizontally or vertically aligned. To do this, we construct four models of shale. The behaviour of P- and S-wave velocities is analysed when gas- and water-filled cracks embedded in a host matrix are randomly oriented, or horizontally or vertically aligned. The host matrix can be either isotropic or anisotropic (of VTI symmetry). In such a modelling, we use published data on mineralogy and clay platelet alignment along with other micromechanical measurements. In the model, where the host matrix is isotropic, the presence of a singularity point (when the difference VS1 - VS2 changes its sign) in shear wave velocities is an indicator of brine-filled aligned cracks. In the model with the VTI host matrix and horizontally aligned cracks filled with gas, an increase in their volume concentration leads to that the azimuth at which the singularity is observed moves toward the symmetry axis. In this case, if the clay content is small (around 20 per cent), the

  14. Large Flexoelectric Anisotropy in Paraelectric Barium Titanate.

    Science.gov (United States)

    Narvaez, Jackeline; Saremi, Sahar; Hong, Jiawang; Stengel, Massimiliano; Catalan, Gustau

    2015-07-17

    The bending-induced polarization of barium titanate single crystals has been measured with an aim to elucidate the origin of the large difference between theoretically predicted and experimentally measured flexoelectricity in this material. The results indicate that part of the difference is due to polar regions (short-range order) that exist above T(C) and up to T*≈200-225 °C. Above T*, however, the flexovoltage coefficient still shows an unexpectedly large anisotropy for a cubic material, with (001)-oriented crystals displaying 10 times more flexoelectricity than (111)-oriented crystals. Theoretical analysis shows that this anisotropy cannot be a bulk property, and we therefore interpret it as indirect evidence for the theoretically predicted but experimentally elusive contribution of surface piezoelectricity to macroscopic bending-induced polarization.

  15. Seismic anisotropy in deforming salt bodies

    Science.gov (United States)

    Prasse, P.; Wookey, J. M.; Kendall, J. M.; Dutko, M.

    2017-12-01

    Salt is often involved in forming hydrocarbon traps. Studying salt dynamics and the deformation processes is important for the exploration industry. We have performed numerical texture simulations of single halite crystals deformed by simple shear and axial extension using the visco-plastic self consistent approach (VPSC). A methodology from subduction studies to estimate strain in a geodynamic simulation is applied to a complex high-resolution salt diapir model. The salt diapir deformation is modelled with the ELFEN software by our industrial partner Rockfield, which is based on a finite-element code. High strain areas at the bottom of the head-like strctures of the salt diapir show high amount of seismic anisotropy due to LPO development of halite crystals. The results demonstrate that a significant degree of seismic anisotropy can be generated, validating the view that this should be accounted for in the treatment of seismic data in, for example, salt diapir settings.

  16. Large Flexoelectric Anisotropy in Paraelectric Barium Titanate

    Science.gov (United States)

    Narvaez, Jackeline; Saremi, Sahar; Hong, Jiawang; Stengel, Massimiliano; Catalan, Gustau

    2015-07-01

    The bending-induced polarization of barium titanate single crystals has been measured with an aim to elucidate the origin of the large difference between theoretically predicted and experimentally measured flexoelectricity in this material. The results indicate that part of the difference is due to polar regions (short-range order) that exist above TC and up to T*≈2 00 - 2 2 5 °C . Above T* , however, the flexovoltage coefficient still shows an unexpectedly large anisotropy for a cubic material, with (001)-oriented crystals displaying 10 times more flexoelectricity than (111)-oriented crystals. Theoretical analysis shows that this anisotropy cannot be a bulk property, and we therefore interpret it as indirect evidence for the theoretically predicted but experimentally elusive contribution of surface piezoelectricity to macroscopic bending-induced polarization.

  17. Anisotropies in the cosmic microwave background: Theory

    International Nuclear Information System (INIS)

    Dodelson, S.

    1998-02-01

    Anisotropies in the Cosmic Microwave Background (CMB) contain a wealth of information about the past history of the universe and the present values of cosmological parameters. I online some of the theoretical advances of the last few years. In particular, I emphasize that for a wide class of cosmological models, theorists can accurately calculate the spectrum to better than a percent. The spectrum of anisotropies today is directly related to the pattern of inhomogeneities present at the time of recombination. This recognition leads to a powerful argument that will enable us to distinguish inflationary models from other models of structure formation. If the inflationary models turn out to be correct, the free parameters in these models will be determined to unprecedented accuracy by the upcoming satellite missions

  18. Ultrasonic evaluation of local human skin anisotropy

    Czech Academy of Sciences Publication Activity Database

    Tokar, Daniel; Převorovský, Zdeněk; Hradilová, Jana

    2014-01-01

    Roč. 19, č. 12 (2014) ISSN 1435-4934. [European Conference on Non-Destructive Testing (ECNDT 2014) /11./. Praha, 06.10.2014-10.10.2014] Institutional support: RVO:61388998 Keywords : anisotropy * ultrasonic testing * human skin in-vivo * fabric-fiber composite * signal processing Subject RIV: BI - Acoustics http://www.ndt.net/events/ECNDT2014/app/content/Paper/324_Tokar.pdf

  19. One-loop anisotropy for improved actions

    OpenAIRE

    Perez, Margarita Garcia; van Baal, Pierre

    1996-01-01

    We determine the one-loop correction to the anisotropy factor for the square Symanzik improved lattice action, extracted fromthe finite volume effective action for SU(N) gauge theories in the background of a zero-momentum gauge field. The result is smaller by approximately a factor 3 than the one-loop correction for the anisotropic Wilson action. We also comment on the Hamiltonian limit.

  20. Experimental investigation of ultrasonic velocity anisotropy in ...

    Indian Academy of Sciences (India)

    Permanent link: http://www.ias.ac.in/article/fulltext/pram/077/02/0345-0355. Keywords. Magnetic fluids; ultrasonic wave; sound velocity; anisotropy. Abstract. Magnetic field-induced dispersion of ultrasonic velocity in a Mn0.7Zn0.3Fe2O4 fluid (applied magnetic field is perpendicular to the ultrasonic propagation vector) is ...

  1. Assessment of velocity anisotropy in rocks

    Czech Academy of Sciences Publication Activity Database

    Lokajíček, Tomáš; Goel, R. K.; Rudajev, Vladimír; Dwivedi, R.D.

    2013-01-01

    Roč. 57, January (2013), s. 142-152 ISSN 1365-1609 R&D Projects: GA ČR(CZ) GA205/08/0676; GA AV ČR IAA300130906; GA ČR(CZ) GAP104/12/0915 Institutional research plan: CEZ:AV0Z30130516 Keywords : elastic anisotropy * acoustic emission * uniaxial loading * hydrostatic loading Subject RIV: DB - Geology ; Mineralogy Impact factor: 1.424, year: 2013

  2. Experimental investigation of ultrasonic velocity anisotropy in ...

    Indian Academy of Sciences (India)

    Permanent link: https://www.ias.ac.in/article/fulltext/pram/077/02/0345-0355. Keywords. Magnetic fluids; ultrasonic wave; sound velocity; anisotropy. Abstract. Magnetic field-induced dispersion of ultrasonic velocity in a Mn0.7Zn0.3Fe2O4 fluid (applied magnetic field is perpendicular to the ultrasonic propagation vector) is ...

  3. Cosmic background radiation anisotropy in an open inflation, cold dark matter cosmogony

    Science.gov (United States)

    Kamionkowski, Marc; Ratra, Bharat; Spergel, David N.; Sugiyama, Naoshi

    1994-01-01

    We compute the cosmic background radiation anisotropy, produced by energy-density fluctuations generated during an early epoch of inflation, in an open cosmological model based on the cold dark matter scenario. At Omega(sub 0) is approximately 0.3-0.4, the Cosmic Background Explorer (COBE) normalized open model appears to be consistent with most observations.

  4. Anisotropy of permeability in faulted porous sandstones

    Science.gov (United States)

    Farrell, N. J. C.; Healy, D.; Taylor, C. W.

    2014-06-01

    Studies of fault rock permeabilities advance the understanding of fluid migration patterns around faults and contribute to predictions of fault stability. In this study a new model is proposed combining brittle deformation structures formed during faulting, with fluid flow through pores. It assesses the impact of faulting on the permeability anisotropy of porous sandstone, hypothesising that the formation of fault related micro-scale deformation structures will alter the host rock porosity organisation and create new permeability pathways. Core plugs and thin sections were sampled around a normal fault and oriented with respect to the fault plane. Anisotropy of permeability was determined in three orientations to the fault plane at ambient and confining pressures. Results show that permeabilities measured parallel to fault dip were up to 10 times higher than along fault strike permeability. Analysis of corresponding thin sections shows elongate pores oriented at a low angle to the maximum principal palaeo-stress (σ1) and parallel to fault dip, indicating that permeability anisotropy is produced by grain scale deformation mechanisms associated with faulting. Using a soil mechanics 'void cell model' this study shows how elongate pores could be produced in faulted porous sandstone by compaction and reorganisation of grains through shearing and cataclasis.

  5. A New Light-Speed Anisotropy Experiment: Absolute Motion and Gravitational Waves Detected

    Directory of Open Access Journals (Sweden)

    Cahill R. T.

    2006-10-01

    Full Text Available Data from a new experiment measuring the anisotropy of the one-way speed of EM waves in a coaxial cable, gives the speed of light as 300,000 +/- 400 (+/- 20 km/s in a measured direction RA=5.5 +/- 2 hrs, Dec=70 +/- 10 Deg S, is shown to be in excellent agreement with the results from seven previous anisotropy experiments, particularly those of Miller (1925/26, and even those of Michelson and Morley (1887. The Miller gas-mode interferometer results, and those from the RF coaxial cable experiments of Torr and Kolen (1983, De Witte (1991 and the new experiment all reveal the presence of gravitational waves, as indicated by the last +/- variations above, but of a kind different from those supposedly predicted by General Relativity. Miller repeated the Michelson-Morley 1887 gas-mode interferometer experiment and againdetected the anisotropy of the speed of light, primarily in the years 1925/1926 atop Mt.Wilson, California. The understanding of the operation of the Michelson interferometer in gas-mode was only achieved in 2002 and involved a calibration for the interferometer that necessarily involved Special Relativity effects and the refractive index of the gas in the light paths. The results demonstrate the reality of the Fitzgerald-Lorentz contraction as an observer independent relativistic effect. A common misunderstanding is that the anisotropy of the speed of light is necessarily in conflict with Special Relativity and Lorentz symmetry - this is explained. All eight experiments and theory show that we have both anisotropy of the speed of light and relativistic effects, and that a dynamical 3-space exists - that absolute motion through that space has been repeatedly observed since 1887. These developments completely change fundamental physics and our understanding of reality. Modern vacuum-mode Michelson interferometers, particularly the long baseline terrestrial versions, are, by design flaw, incapable of detecting the anisotropy effect and the

  6. HST/COS Observations of the Quasar HE 2347-4342: Probing the Epoch of He II Patchy Reionization at Redshifts z = 2.4-2.9

    Science.gov (United States)

    Shull, J. Michael; France, Kevin; Danforth, Charles W.; Smith, Britton; Tumlinson, Jason

    2010-10-01

    We report ultraviolet spectra of the high-redshift (z em ≈ 2.9) quasar, HE 2347 - 4342, taken by the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope. Spectra in the G130M (medium resolution, 1135-1440 Å) and G140L (low resolution, 1030-2000 Å) gratings exhibit patchy Gunn-Peterson absorption in the 303.78 Å Lyα line of He II between z = 2.39-2.87 (G140L) and z = 2.74-2.90 (G130M). With COS, we obtain better spectral resolution, higher signal-to-noise ratio (S/N), and better determined backgrounds than previous studies, with sensitivity to abundance fractions x He II ≈ 0.01 in filaments of the cosmic web. The He II optical depths from COS are higher than those with the Far Ultraviolet Spectroscopic Explorer and range from τHe II = 5, with a slow recovery in mean optical depth to langτHe II rang numerous flux-transmission windows between 1135 and 1186 Å. The He II absorption extends to 1186.26 Å (z = 2.905), including associated absorbers with z abs ≈ z QSO and minimal "proximity effect" of flux transmission at the He II edge. We propose a QSO systemic redshift z QSO = 2.904 ± 0.002, some Δz = 0.019 higher than that derived from O I λ1302 emission. Three long troughs (4-10 Å or 25-60 Mpc comoving distance) of strong He II absorption between z = 2.75and2.90 are uncharacteristic of the intergalactic medium if He II reionized at zr ≈ 3. Contrary to recent indirect estimates (zr = 3.2 ± 0.2) from H I optical depths, the epoch of He II reionization may extend to z <~ 2.7. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS5-26555.

  7. Tailoring perpendicular magnetic anisotropy with graphene oxide membranes

    KAUST Repository

    Ning, Keyu

    2017-11-15

    Graphene oxide (GO) membranes have been widely explored for their excellent physical and chemical properties, and abundant functional groups. In this work, we report the improvement of the perpendicular magnetic anisotropy (PMA) of CoFeB thin films by applying a coating of GO membranes. We observe that the PMA of the CoFeB/MgAl–O stacks is strongly enhanced by the coating of GO membranes and even reaches 0.6 mJ m−2 at room temperature after an annealing process. The critical thickness of the membrane-coated CoFeB for switching the magnetization from the out-of-plane to the in-plane axis exceeds 1.6 nm. First-principle calculations are performed to investigate the contribution of the GO membranes to the magnetic anisotropy energy (MAE). Due to changes in the hybridization of 3d orbitals, varying the location of the C atomic layer with Co changes the contribution of the Co–C stacks to PMA. Thus, the large PMA achieved with GO membranes can be attributed to the orbital hybridization of the C and O atoms with the Co orbitals. These results provide a comprehensive understanding of the PMA and point towards opportunities to achieve multifunctional graphene-composite spintronic devices.

  8. Fragment Angular Anisotropies for Magic and Non-Magic Nuclei

    Science.gov (United States)

    Behkami, A. N.; Maroofi, S.; Esmailipour, A.; Rasooli, S.

    2007-10-01

    Fission fragment angular distributions have been studied for ^239 Pu (n, f) reaction at several neutron energies. Theoretical calculations have been utilized to determine the variance K0^2 at each bombarding energy from the observed angular anisotropies. The values of K0^2 show sharp rise from a value of 5-6 to about 13 for higher neutron energies. From the position of one of the breaks in the K0^2 value, the magnitude of the pairing gap 2δ in the highly deformed transition nucleus ^240 Pu is estimated to be 2.4 MeV. Fission fragment angular anisotropies from changed particle fission of ^208 Pb, ^209 Bi, ^235U and ^238U at laboratory energy of 43.0 MeV have also been analyzed using the traditional transition state model. In all these calculations, optical model transmission coefficients with spin-orbit interaction have been used. In the case of magic nuclei, ^208Pb and ^209 Bi it is found that the deduced values of K0^2 are very small as compared to their corresponding values for ^235U and ^238U nuclei. This interpreted as due to shell structure, since significant shell and pairing effects appear for the magic nuclei ^208 Pb and ^209 Bi.

  9. A laboratory goniometer system for measuring reflectance and emittance anisotropy.

    Science.gov (United States)

    Roosjen, Peter P J; Clevers, Jan G P W; Bartholomeus, Harm M; Schaepman, Michael E; Schaepman-Strub, Gabriela; Jalink, Henk; van der Schoor, Rob; de Jong, Arjan

    2012-12-13

    In this paper, a laboratory goniometer system for performing multi-angular measurements under controlled illumination conditions is described. A commercially available robotic arm enables the acquisition of a large number of measurements over the full hemisphere within a short time span making it much faster than other goniometers. In addition, the presented set-up enables assessment of anisotropic reflectance and emittance behaviour of soils, leaves and small canopies. Mounting a spectrometer enables acquisition of either hemispherical measurements or measurements in the horizontal plane. Mounting a thermal camera allows directional observations of the thermal emittance. This paper also presents three showcases of these different measurement set-ups in order to illustrate its possibilities. Finally, suggestions for applying this instrument and for future research directions are given, including linking the measured reflectance anisotropy with physically-based anisotropy models on the one hand and combining them with field goniometry measurements for joint analysis with remote sensing data on the other hand. The speed and flexibility of the system offer a large added value to the existing pool of laboratory goniometers.

  10. Effects of substrate anisotropy and edge diffusion on submonolayer growth during molecular beam epitaxy: A Kinetic Monte Carlo study

    International Nuclear Information System (INIS)

    Devkota, J.; Shrestha, S.P.

    2007-12-01

    We have performed Kinetic Monte Carlo simulation work to study the effect of diffusion anisotropy, bonding anisotropy and edge diffusion on island formation at different temperatures during the sub-monolayer film growth in Molecular Beam Epitaxy. We use simple cubic solid on solid model and event based Bortz, Kalos and Labowitch (BKL) algorithm on the Kinetic Monte Carlo method to simulate the physical phenomena. We have found that the island morphology and growth exponent are found to be influenced by substrate anisotropy as well as edge diffusion, however they do not play a significant role in island elongation. The growth exponent and island size distribution are observed to be influenced by substrate anisotropy but are negligibly influenced by edge diffusion. We have found fractal islands when edge diffusion is excluded and compact islands when edge diffusion is included. (author)

  11. WMAP haze: Directly observing dark matter?

    International Nuclear Information System (INIS)

    Forbes, Michael McNeil; Zhitnitsky, Ariel R.

    2008-01-01

    In this paper, we show that dark matter in the form of dense matter/antimatter nuggets could provide a natural and unified explanation for several distinct bands of diffuse radiation from the core of the Galaxy spanning over 13 orders of magnitude in frequency. We fix all of the phenomenological properties of this model by matching to x-ray observations in the keV band, and then calculate the unambiguously predicted thermal emission in the microwave band, at frequencies smaller by 11 orders of magnitude. Remarkably, the intensity and spectrum of the emitted thermal radiation are consistent with - and could entirely explain - the so-called 'WMAP haze': a diffuse microwave excess observed from the core of our Galaxy by the Wilkinson Microwave Anisotropy Probe (WMAP). This provides another strong constraint of our proposal, and a remarkable nontrivial validation. If correct, our proposal identifies the nature of the dark matter, explains baryogenesis, and provides a means to directly probe the matter distribution in our Galaxy by analyzing several different types of diffuse emissions.

  12. Probing leptogenesis

    DEFF Research Database (Denmark)

    Chun, E. J.; Cvetič, G.; Dev, P. S.B.

    2018-01-01

    present a way to falsify such scenarios by focusing on their washout processes. This is discussed specifically for the left-right symmetric model and the observation of a heavy WR, as well as model independently when measuring L = 2 washout processes at the LHC or neutrinoless double beta decay.......The focus of this paper lies on the possible experimental tests of leptogenesis scenarios. We consider both leptogenesis generated from oscillations, as well as leptogenesis from out-of-equilibrium decays. As the Akhmedov-Rubakov-Smirnov (ARS) mechanism allows for heavy neutrinos in the GeV range......, this opens up a plethora of possible experimental tests, e.g. at neutrino oscillation experiments, neutrinoless double beta decay, and direct searches for neutral heavy leptons at future facilities. In contrast, testing leptogenesis from out-of-equilibrium decays is a quite difficult task. We comment...

  13. Nine New Fluorescent Probes

    Science.gov (United States)

    Lin, Tsung-I.; Jovanovic, Misa V.; Dowben, Robert M.

    1989-06-01

    Absorption and fluorescence spectroscopic studies are reported here for nine new fluorescent probes recently synthesized in our laboratories: four pyrene derivatives with substituents of (i) 1,3-diacetoxy-6,8-dichlorosulfonyl, (ii) 1,3-dihydroxy-6,8-disodiumsulfonate, (iii) 1,3-disodiumsulfonate, and (iv) l-ethoxy-3,6,8-trisodiumsulfonate groups, and five [7-julolidino] coumarin derivatives with substituents of (v) 3-carboxylate-4-methyl, (vi) 3- methylcarboxylate, (vii) 3-acetate-4-methyl, (viii) 3-propionate-4-methyl, and (ix) 3-sulfonate-4-methyl groups. Pyrene compounds i and ii and coumarin compounds v and vi exhibit interesting absorbance and fluorescence properties: their absorption maxima are red shifted compared to the parent compound to the blue-green region, and the band width broadens considerably. All four blue-absorbing dyes fluoresce intensely in the green region, and the two pyrene compounds emit at such long wavelengths without formation of excimers. The fluorescence properties of these compounds are quite environment-sensitive: considerable spectral shifts and fluorescence intensity changes have been observed in the pH range from 3 to 10 and in a wide variety of polar and hydrophobic solvents with vastly different dielectric constants. The high extinction and fluorescence quantum yield of these probes make them ideal fluorescent labeling reagents for proteins, antibodies, nucleic acids, and cellular organelles. The pH and hydrophobicity-dependent fluorescence changes can be utilized as optical pH and/or hydrophobicity indicators for mapping environmental difference in various cellular components in a single cell. Since all nine probes absorb in the UV, but emit at different wavelengths in the visible, these two groups of compounds offer an advantage of utilizing a single monochromatic light source (e.g., a nitrogen laser) to achieve multi-wavelength detection for flow cytometry application. As a first step to explore potential application in

  14. Controlling the magnetic anisotropy in epitaxial Y3F e5O12 films by manganese doping

    Science.gov (United States)

    Wang, C. T.; Liang, X. F.; Zhang, Y.; Liang, X.; Zhu, Y. P.; Qin, J.; Gao, Y.; Peng, B.; Sun, N. X.; Bi, L.

    2017-12-01

    Controlling the magnetic anisotropy in epitaxial Y3F e5O12 (YIG) thin films is critical for magnonic and photonic device applications. In this paper, we report the crystal structure, magnetic properties, and magnetic anisotropy of epitaxial Y3(F e5 -xM nx ) O12 (Mn:YIG) thin films grown on G d3G a5O12 (111) (GGG) substrates by pulsed-laser deposition. Mn doping is observed to strongly enhance the magnetoelastic coefficient of YIG thin films, which leads to large tunability of the thin film magnetic anisotropy by lattice strain. With increasing Mn concentration from x =0 to x =1.25 , a continuous increase of out-of-plane magnetic anisotropy ranging from -644.4 Oe to 1337.5 Oe is observed. In particular, a perpendicular magnetic anisotropy (PMA) is achieved in Mn:YIG thin films with a high Mn concentration of x =1.12 . Ferromagnetic resonance (FMR) measurements show low FMR linewidths of 3.4 Oe to 129 Oe at 9.5 GHz in Mn:YIG thin films. Our paper demonstrates manganese doping as an effective way to enhance the magnetoelastic anisotropy of YIG thin films by strain, which is useful for magnonic and magneto-optical device applications.

  15. Anisotropy-Guided Enantiomeric Enhancement in Alanine Using Far-UV Circularly Polarized Light.

    Science.gov (United States)

    Meinert, Cornelia; Cassam-Chenaï, Patrick; Jones, Nykola C; Nahon, Laurent; Hoffmann, Søren V; Meierhenrich, Uwe J

    2015-06-01

    All life on Earth is characterized by its asymmetry - both the genetic material and proteins are composed of homochiral monomers. Understanding how this molecular asymmetry initially arose is a key question related to the origins of life. Cometary ice simulations, L-enantiomeric enriched amino acids in meteorites and the detection of circularly polarized electromagnetic radiation in star-forming regions point to a possible interstellar/protostellar generation of stereochemical asymmetry. Based upon our recently recorded anisotropy spectra g(λ) of amino acids in the vacuum-UV range, we subjected amorphous films of racemic (13)C-alanine to far-UV circularly polarized synchrotron radiation to probe the asymmetric photon-molecule interaction under interstellar conditions. Optical purities of up to 4% were reached, which correlate with our theoretical predictions. Importantly, we show that chiral symmetry breaking using circularly polarized light is dependent on both the helicity and the wavelength of incident light. In order to predict such stereocontrol, time-dependent density functional theory was used to calculate anisotropy spectra. The calculated anisotropy spectra show good agreement with the experimental ones. The European Space Agency's Rosetta mission, which successfully landed Philae on comet 67P/Churyumov-Gerasimenko on 12 November 2014, will investigate the configuration of chiral compounds and thereby obtain data that are to be interpreted in the context of the results presented here.

  16. FRACTIONAL ANISOTROPY OF THE FORNIX AND HIPPOCAMPAL ATROPHY IN ALZHEIMER’S DISEASE

    Directory of Open Access Journals (Sweden)

    Kejal eKantarci

    2014-11-01

    Full Text Available Decrease in the directionality of water diffusion measured with fractional anisotropy on diffusion tensor imaging has been linked to loss of myelin and axons in the white matter. Fornix fractional anisotropy is consistently decreased in patients with mild cognitive impairment and Alzheimer’s disease. Furthermore, decreased fornix fractional anisotropy is one of the earliest MRI abnormalities observed in cognitively normal individuals who are at an increased risk for Alzheimer’s disease, such as in pre-symptomatic carriers of familial Alzheimer’s disease mutations and in pre-clinical Alzheimer’s disease. Reductions of fractional anisotropy at these early stages which predicted the decline in memory function. Fornix carries the efferent projections from the CA1 and CA3 pyramidal neurons of the hippocampus and subiculum, connecting these structures to the septal nuclei, anterior thalamic nucleus, mammillary bodies and medial hypothalamus. Fornix also carries the afferent cholinergic and GABAergic projections from the medial septal nuclei and the adjacent diagonal band back to the medial temporal lobe, interconnecting the core limbic structures. Because fornix carries the axons projecting from the hippocampus, integrity of the fornix is in-part linked to the integrity of the hippocampus. In keeping with that, fornix fractional anisotropy is reduced in subjects with hippocampal atrophy, correlating with memory function. The literature on fractional anisotropy reductions in the fornix in the clinical spectrum of Alzheimer’s disease from pre-symptomatic carriers of familial Alzheimer’s disease mutations to pre-clinical Alzheimer’s disease, mild cognitive impairment and dementia stages is reviewed.

  17. Probing 2D black phosphorus by quantum capacitance measurements.

    Science.gov (United States)

    Kuiri, Manabendra; Kumar, Chandan; Chakraborty, Biswanath; Gupta, Satyendra N; Naik, Mit H; Jain, Manish; Sood, A K; Das, Anindya

    2015-12-04

    Two-dimensional materials and their heterostructures have emerged as a new class of materials, not only for fundamental physics but also for electronic and optoelectronic applications. Black phosphorus (BP) is a relatively new addition to this class of materials. Its strong in-plane anisotropy makes BP a unique material for making conceptually new types of electronic devices. However, the global density of states (DOS) of BP in device geometry has not been measured experimentally. Here, we report the quantum capacitance measurements together with the conductance measurements on an hBN-protected few-layer BP (∼six layers) in a dual-gated field effect transistor (FET) geometry. The measured DOS from our quantum capacitance is compared with density functional theory (DFT). Our results reveal that the transport gap for quantum capacitance is smaller than that in conductance measurements due to the presence of localized states near the band edge. The presence of localized states is confirmed by the variable range hopping seen in our temperature dependence conductivity. A large asymmetry is observed between the electron and hole side. This asymmetric nature is attributed to the anisotropic band dispersion of BP. Our measurements establish the uniqueness of quantum capacitance in probing the localized states near the band edge, hitherto not seen in conductance measurements.

  18. Report on 1988 research result on the R and D of observation system for probing resources. 3/3; 1988 nendo shigen tansayo kansoku system no kenkyu kaihatsu. 3/3

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1989-07-01

    This paper explains the 1988 results of the specialized study in the R and D of the observation system for probing resources. In the system development of the synthetic-aperture radar (SAR) to be loaded on the earth resources satellite ERS-1, the basic design was reexamined, with an SAR system test carried out. A combination test was performed for SAR and the mission transmitter. The testing device was also improved and manufactured. The optical sensor needs to be a system that uses a wide wavelength area and that is capable of receiving a image data of a high surface resolution; accordingly, on the basis of 1988 results, it was tested by preparing an engineering model (EM). The mission recording device records the observation data of SAR and the optical sensor in an invisible area, reproduces it in a visible area in the ground station, and obtains data. The EM development test implemented in fiscal 1987 was continued for the electronics part and the transport part, with the specifications and interface control documents established simultaneously. Combination tests with the mission transmitter were carried out. Studies were also stated on the antenna part/transmitter part of the mission transmitter. (NEDO)

  19. Shear wave splitting and crustal anisotropy in the Eastern Ladakh-Karakoram zone, northwest Himalaya

    Science.gov (United States)

    Paul, Arpita; Hazarika, Devajit; Wadhawan, Monika

    2017-06-01

    Seismic anisotropy of the crust beneath the eastern Ladakh-Karakoram zone has been studied by shear wave splitting analysis of S-waves of local earthquakes and P-to-S or Ps converted phases originated at the crust-mantle boundary. The splitting parameters (Φ and δt), derived from S-wave of local earthquakes with shallow focal depths, reveal complex nature of anisotropy with NW-SE and NE oriented Fast Polarization directions (FPD) in the upper ∼22 km of the crust. The observed anisotropy in the upper crust may be attributed to combined effects of existing tectonic features as well as regional tectonic stress. The maximum delay time of fast and slow waves in the upper crust is ∼0.3 s. The Ps splitting analysis shows more consistent FPDs compared to S-wave splitting. The FPDs are parallel or sub parallel to the Karakoram fault (KF) and other NW-SE trending tectonic features existing in the region. The strength of anisotropy estimated for the whole crust is higher (maximum delay time δt: 0.75 s) in comparison to the upper crust. This indicates that the dominant source of anisotropy in the trans-Himalayan crust is confined within the middle and lower crustal depths. The predominant NW-SE trending FPDs consistently observed in the upper crust as well as in the middle and lower crust near the KF zone support the fact that the KF is a crustal-scale fault which extends at least up to the lower crust. Dextral shearing of the KF creates shear fabric and preferential alignment of mineral grains along the strike of the fault, resulting in the observed FPDs. A Similar observation in the Indus Suture Zone (ISZ) also suggests crustal scale deformation owing to the India-Asia collision.

  20. THE ORNL ATOM PROBE

    OpenAIRE

    Miller, M.

    1986-01-01

    The ORNL Atom Probe is a microanalytical tool for studies in materials science. The instrument is a combination of a customized version of the vacuum system of the VG FIM-100 atom probe, an ORNL-designed microcomputer-controlled digital timing system, and a double curved CEMA Imaging Atom Probe detector. The atom probe combines four instruments into one - namely a field ion microscope, an energy compensated time-of-flight mass spectrometer, an imaging atom probe, and a pulsed laser atom probe.

  1. Mobile Game Probes

    DEFF Research Database (Denmark)

    Borup Lynggaard, Aviaja

    2006-01-01

    This paper will examine how probes can be useful for game designers in the preliminary phases of a design process. The work is based upon a case study concerning pervasive mobile phone games where Mobile Game Probes have emerged from the project. The new probes are aimed towards a specific target...... group and the goal is to specify the probes so they will cover the most relevant areas for our project. The Mobile Game Probes generated many interesting results and new issues occurred, since the probes came to be dynamic and favorable for the process in new ways....

  2. Backscatter, anisotropy, and polarization of solar hard X-rays

    International Nuclear Information System (INIS)

    Bai, T.; Ramaty, R.

    1978-01-01

    Hard X-rays incident upon the photosphere with energies > or approx. =15 keV have high probabilities of backscatter due to Compton collisions with electrons. This effect has a strong influence on the spectrum, intensity, and polarization of solar hard X-rays - especially for anisotropic models in which the primary X-rays are emitted predominantly toward the photosphere. We have carried out a detailed study of X-ray backscatter, and we have investigated the interrelated problems of anisotropy, polarization, center-to-limb variation of the X-ray spectrum, and Compton backscatter in a coherent fashion. The results of this study are compared with observational data. Because of the large contribution from backscatter, for an anisotropic primary X-ray source which is due to bremsstrahlung of accelerated electrons moving predominantly down toward the photosphere, the observed X-ray flux around 30 keV does not depend significantly on the position of flare on the Sun. For such an anisotropic source, the X-ray spectrum observed in the 15-50 keV range becomes steeper with the increasing heliocentric angle of the flare. These results are compatible with the data. The degree of polarization of the sum of the primary and reflected X-rays with energies between about 15 and 30 keV can be very large for anisotropic primary X-ray sources, but it is less than about 4% for isotropic sources. We also discuss the characteristics of the brightness distribution of the X-ray albedo patch created by the Compton backscatter. The height and anisotropy of the primary hard X-ray source might be inferred from the study of the albedo patch

  3. Photoelectron angular distributions from polar molecules probed by intense femtosecond lasers

    DEFF Research Database (Denmark)

    Abu-Samha, Mahmoud; Madsen, Lars Bojer

    2010-01-01

    -active-electron and frozen-nuclei approximations. Our analysis shows that for the HF and LiF molecules, anisotropies in the molecular potential and the probed orbital lead to enhanced ionization during laser half cycles with the field pointing antiparallel to the permanent dipole of the dipole term in a multipolar expansion...

  4. On the Acceleration and Anisotropy of Ions Within Magnetotail Dipolarizing Flux Bundles

    Science.gov (United States)

    Zhou, Xu-Zhi; Runov, Andrei; Angelopoulos, Vassilis; Artemyev, Anton V.; Birn, Joachim

    2018-01-01

    Dipolarizing flux bundles (DFBs), earthward propagating structures with enhanced northward magnetic field Bz, are usually believed to carry a distinctly different plasma population from that in the ambient magnetotail plasma sheet. The ion distribution functions within the DFB, however, have been recently found to be largely controlled by the ion adiabaticity parameter κ in the ambient plasma sheet outside the DFB. According to these observations, the ambient κ values of 2-3 usually correspond to a strong perpendicular anisotropy of suprathermal ions within the DFB, whereas for lower κ values the DFB ions become more isotropic. Here we utilize a simple, test particle model to explore the nature of the anisotropy and its dependence on the ambient κ values. We find that the anisotropy originates from successive ion reflections and reentries to the DFB, during which the ions are consecutively accelerated in the perpendicular direction by the DFB-associated electric field. This consecutive acceleration may be interrupted, however, when magnetic field lines are highly curved in the ambient plasma sheet. In this case, the ion trajectories become stochastic outside the DFB, which makes the reflected ions less likely to return to the DFB for another cycle of acceleration; as a consequence, the perpendicular ion anisotropy does not appear. Given that the DFB ions are a free energy source for instabilities when they are injected toward Earth, our simple model (that reproduces most observational features on the anisotropic DFB ion distributions) may shed new lights on the coupling process between magnetotail and inner magnetosphere.

  5. Studies of anisotropy of iron based superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Murphy, Jason [Iowa State Univ., Ames, IA (United States)

    2013-01-01

    To study the electronic anisotropy in iron based superconductors, the temperature dependent London penetration depth, Δλ (T), have been measured in several compounds, along with the angular dependent upper critical field, Hc2(T). Study was undertaken on single crystals of Ba(Fe1-xCox)2As2 with x=0.108 and x=0.127, in the overdoped range of the doping phase diagram, characterized by notable modulation of the superconducting gap. Heavy ion irradiation with matching field doses of 6 T and 6.5 T respectively, were used to create columnar defects and to study their effect on the temperature Δλ (T). The variation of the low-temperature penetration depth in both pristine and irradiated samples was fitted with a power-law function Δλ (T) = ATn. Irradiation increases the magnitude of the pre-factor A and decreases the exponent n, similar to the effect on the optimally doped samples. This finding supports the universal s± scenario for the whole doping range. Knowing that the s± gap symmetry exists across the superconducting dome for the electron doped systems, we next looked at λ (T), in optimally - doped, SrFe2(As1-xPx)2, x =0.35. Both, as-grown (Tc ~ 25 K) and annealed (Tc ~ 35 K) single crystals of SrFe2(As1-xPx)2 were measured. Annealing decreases the absolute value of the London penetration depth from λ(0) = 300 ± 10 nm in as-grown samples to λ (0) = 275±10 nm. At low temperatures, λ (T) ~ T indicates a superconducting gap with line nodes. Analysis of the full-temperature range superfluid density is consistent with the line nodes, but differs from the simple single-gap d-wave. The observed behavior is very similar to that of BaFe2(As1-xPx)2, showing that isovalently substituted pnictides are inherently different from

  6. Altered Fractional Anisotropy in Early Huntington's Disease

    Directory of Open Access Journals (Sweden)

    Silky Singh

    2013-02-01

    Full Text Available Huntington's disease (HD is a dominantly inherited neurodegenerative disease best known for chorea. The disorder includes numerous other clinical features including mood disorder, eye movement abnormalities, cognitive disturbance, pendular knee reflexes, motor impersistence, and postural instability. We describe a mild case of HD early in the disease course with depression and subtle neurological manifestations. In addition, we review MRI and diffusion tensor imaging features in this patient. The bicaudate ratio, a measure of caudate atrophy, was increased. Fractional anisotropy values of the bilateral caudate and putamen were increased, signifying neurodegeneration of these structures in HD.

  7. Fusion barrier distributions and fission anisotropies

    International Nuclear Information System (INIS)

    Hinde, D.J.; Morton, C.R.; Dasgupta, M.; Leigh, J.R.; Lestone, J.P.; Lemmon, R.C.; Mein, J.C.; Newton, J.O.; Timmers, H.; Rowley, N.; Kruppa, A.T.

    1995-01-01

    Fusion excitation functions for 16,17 O+ 144 Sm have been measured to high precision. The extracted fusion barrier distributions show a double-peaked structure interpreted in terms of coupling to inelastic collective excitations of the target. The effect of the positive Q-value neutron stripping channel is evident in the reaction with 17 O. Fission and evaporation residue cross-sections and excitation functions have been measured for the reaction of 16 O+ 208 Pb and the fusion barrier distribution and fission anisotropies determined. It is found that the moments of the fusion l-distribution determined from the fusion and fission measurements are in good agreement. ((orig.))

  8. Anisotropy in cohesive, frictional granular media

    International Nuclear Information System (INIS)

    Luding, Stefan

    2005-01-01

    The modelling of cohesive, frictional granular materials with a discrete particle molecular dynamics is reviewed. From the structure of the quasi-static granular solid, the fabric, stress, and stiffness tensors are determined, including both normal and tangential forces. The influence of the material properties on the flow behaviour is also reported, including relations between the microscopic attractive force and the macroscopic cohesion as well as the dependence of the macroscopic friction on the microscopic contact friction coefficient. Related to the dynamics, the anisotropy of both structure and stress are exponentially approaching the maximum

  9. Magnetic anisotropy of deposited transition metal clusters

    Science.gov (United States)

    Bornemann, S.; Minár, J.; Staunton, J. B.; Honolka, J.; Enders, A.; Kern, K.; Ebert, H.

    2007-12-01

    We present results of magnetic torque calculations using the fully relativistic spin-polarized Korringa-Kohn-Rostoker approach applied to small Co and Fe clusters deposited on the Pt(111) surface. From the magnetic torque one can derive amongst others the magnetic anisotropy energy (MAE). It was found that this approach is numerically much more stable and also computationally less demanding than using the magnetic force theorem that allows to calculate the MAE directly. Although structural relaxation effects were not included our results correspond reasonably well to recent experimental data.

  10. Fermi-LAT γ-ray anisotropy and intensity explained by unresolved radio-loud active galactic nuclei

    International Nuclear Information System (INIS)

    Mauro, Mattia Di; Cuoco, Alessandro; Donato, Fiorenza; Siegal-Gaskins, Jennifer M.

    2014-01-01

    Radio-loud active galactic nuclei (AGN) are expected to contribute substantially to both the intensity and anisotropy of the isotropic γ-ray background (IGRB). In turn, the measured properties of the IGRB can be used to constrain the characteristics of proposed contributing source classes. We consider individual subclasses of radio-loud AGN, including low-, intermediate-, and high-synchrotron-peaked BL Lacertae objects, flat-spectrum radio quasars, and misaligned AGN. Using updated models of the γ-ray luminosity functions of these populations, we evaluate the energy-dependent contribution of each source class to the intensity and anisotropy of the IGRB. We find that collectively radio-loud AGN can account for the entirety of the IGRB intensity and anisotropy as measured by the Fermi Large Area Telescope (LAT). Misaligned AGN provide the bulk of the measured intensity but a negligible contribution to the anisotropy, while high-synchrotron-peaked BL Lacertae objects provide the dominant contribution to the anisotropy. In anticipation of upcoming measurements with the Fermi-LAT and the forthcoming Cherenkov Telescope Array, we predict the anisotropy in the broader energy range that will be accessible to future observations

  11. Fermi-LAT γ-ray anisotropy and intensity explained by unresolved radio-loud active galactic nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Mauro, Mattia Di; Cuoco, Alessandro; Donato, Fiorenza [Dipartimento di Fisica, Università di Torino, via P. Giuria 1, Torino, 10125 Italy (Italy); Siegal-Gaskins, Jennifer M., E-mail: mattia.dimauro@to.infn.it, E-mail: alessandro.cuoco@to.infn.it, E-mail: donato@to.infn.it, E-mail: jsg@tapir.caltech.edu [California Institute of Technology, 1200 E. California Blvd., Pasadena, CA, 91125 (United States)

    2014-11-01

    Radio-loud active galactic nuclei (AGN) are expected to contribute substantially to both the intensity and anisotropy of the isotropic γ-ray background (IGRB). In turn, the measured properties of the IGRB can be used to constrain the characteristics of proposed contributing source classes. We consider individual subclasses of radio-loud AGN, including low-, intermediate-, and high-synchrotron-peaked BL Lacertae objects, flat-spectrum radio quasars, and misaligned AGN. Using updated models of the γ-ray luminosity functions of these populations, we evaluate the energy-dependent contribution of each source class to the intensity and anisotropy of the IGRB. We find that collectively radio-loud AGN can account for the entirety of the IGRB intensity and anisotropy as measured by the Fermi Large Area Telescope (LAT). Misaligned AGN provide the bulk of the measured intensity but a negligible contribution to the anisotropy, while high-synchrotron-peaked BL Lacertae objects provide the dominant contribution to the anisotropy. In anticipation of upcoming measurements with the Fermi-LAT and the forthcoming Cherenkov Telescope Array, we predict the anisotropy in the broader energy range that will be accessible to future observations.

  12. Interplay of uniaxial and cubic anisotropy in epitaxial Fe thin films on MgO (001 substrate

    Directory of Open Access Journals (Sweden)

    Srijani Mallik

    2014-09-01

    Full Text Available Epitaxial Fe thin films were grown on annealed MgO(001 substrates at oblique incidence by DC magnetron sputtering. Due to the oblique growth configuration, uniaxial anisotropy was found to be superimposed on the expected four-fold cubic anisotropy. A detailed study of in-plane magnetic hysteresis for Fe on MgO thin films has been performed by Magneto Optic Kerr Effect (MOKE magnetometer. Both single step and double step loops have been observed depending on the angle between the applied field and easy axis i.e. along ⟨100⟩ direction. Domain images during magnetization reversal were captured by Kerr microscope. Domain images clearly evidence two successive and separate 90° domain wall (DW nucleation and motion along cubic easy cum uniaxial easy axis and cubic easy cum uniaxial hard axis, respectively. However, along cubic hard axis two 180° domain wall motion dominate the magnetization reversal process. In spite of having four-fold anisotropy it is essential to explain magnetization reversal mechanism in 0°< ϕ < 90° span as uniaxial anisotropy plays a major role in this system. Also it is shown that substrate rotation can suppress the effect of uniaxial anisotropy superimposed on four-fold anisotropy.

  13. Northern Sky Galactic Cosmic Ray Anisotropy between 10 and 1000 TeV with the Tibet Air Shower Array

    Energy Technology Data Exchange (ETDEWEB)

    Amenomori, M. [Department of Physics, Hirosaki University, Hirosaki 036-8561 (Japan); Bi, X. J.; Chen, W. Y.; Ding, L. K.; Feng, Zhaoyang; Gou, Q. B.; Guo, Y. Q.; He, H. H.; Hu, H. B.; Huang, J. [Key Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); Chen, D. [National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Chen, T. L.; Danzengluobu; Hu, Haibing [Department of Mathematics and Physics, Tibet University, Lhasa 850000 (China); Cui, S. W.; He, Z. T. [Department of Physics, Hebei Normal University, Shijiazhuang 050016 (China); Feng, C. F. [Department of Physics, Shandong University, Jinan 250100 (China); Feng, Z. Y. [Institute of Modern Physics, Southwest Jiaotong University, Chengdu 610031 (China); Hibino, K. [Faculty of Engineering, Kanagawa University, Yokohama 221-8686 (Japan); Hotta, N. [Faculty of Education, Utsunomiya University, Utsunomiya 321-8505 (Japan); Collaboration: Tibet AS γ Collaboration; and others

    2017-02-20

    We report on the analysis of the 10–1000 TeV large-scale sidereal anisotropy of Galactic cosmic rays (GCRs) with the data collected by the Tibet Air Shower Array from 1995 October