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Sample records for anisotropy probe wmapobservations

  1. Five-Year Wilkinson Microwave Anisotropy Probe (WMAP)Observations: Beam Maps and Window Functions

    Science.gov (United States)

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

    2008-01-01

    Cosmology and other scientific results from the WMAP mission require an accurate knowledge of the beam patterns in flight. While the degree of beam knowledge for the WMAP one-year and three-year results was unprecedented for a CMB experiment, we have significantly improved the beam determination as part of the five-year data release. Physical optics fits are done on both the A and the B sides for the first time. The cutoff scale of the fitted distortions on the primary mirror is reduced by a factor of approximately 2 from previous analyses. These changes enable an improvement in the hybridization of Jupiter data with beam models, which is optimized with respect to error in the main beam solid angle. An increase in main-beam solid angle of approximately 1% is found for the V2 and W1-W4 differencing assemblies. Although the five-year results are statistically consistent with previous ones, the errors in the five-year beam transfer functions are reduced by a factor of approximately 2 as compared to the three-year analysis. We present radiometry of the planet Jupiter as a test of the beam consistency and as a calibration standard; for an individual differencing assembly. errors in the measured disk temperature are approximately 0.5%.

  2. Results from the Wilkinson Microwave Anisotropy Probe

    Science.gov (United States)

    Komatsu, E.; Bennett, Charles L.; Komatsu, Eiichiro

    2015-01-01

    The Wilkinson Microwave Anisotropy Probe (WMAP) mapped the distribution of temperature and polarization over the entire sky in five microwave frequency bands. These full-sky maps were used to obtain measurements of temperature and polarization anisotropy of the cosmic microwave background with the unprecedented accuracy and precision. The analysis of two-point correlation functions of temperature and polarization data gives determinations of the fundamental cosmological parameters such as the age and composition of the universe, as well as the key parameters describing the physics of inflation, which is further constrained by three-point correlation functions. WMAP observations alone reduced the flat ? cold dark matter (Lambda Cold Dark Matter) cosmological model (six) parameter volume by a factor of > 68, 000 compared with pre-WMAP measurements. The WMAP observations (sometimes in combination with other astrophysical probes) convincingly show the existence of non-baryonic dark matter, the cosmic neutrino background, flatness of spatial geometry of the universe, a deviation from a scale-invariant spectrum of initial scalar fluctuations, and that the current universe is undergoing an accelerated expansion. The WMAP observations provide the strongest ever support for inflation; namely, the structures we see in the universe originate from quantum fluctuations generated during inflation.

  3. Anisotropies in the cosmic neutrino background after Wilkinson Microwave Anisotropy Probe five-year data

    International Nuclear Information System (INIS)

    We search for the presence of cosmological neutrino background (CNB) anisotropies in recent Wilkinson Microwave Anisotropy Probe (WMAP) five-year data using their signature imprinted on modifications to the cosmic microwave background (CMB) anisotropy power spectrum. By parameterizing the neutrino background anisotropies with the speed viscosity parameter cvis, we find that the WMAP five-year data alone provide only a weak indication for CNB anisotropies with cvis2>0.06 at the 95% confidence level. When we combine CMB anisotropy data with measurements of galaxy clustering, the SN-Ia Hubble diagram, and other cosmological information, the detection increases to cvis2>0.16 at the same 95% confidence level. Future data from Planck, combined with a weak lensing survey such as the one expected with DUNE from space, will be able to measure the CNB anisotropy parameter at about 10% accuracy. We discuss the degeneracy between neutrino background anisotropies and other cosmological parameters such as the number of effective neutrinos species and the dark energy equation of state

  4. Wilkinson Microwave Anisotropy Probe (WMAP) Attitude Estimation Filter Comparison

    Science.gov (United States)

    Harman, Richard R.

    2005-01-01

    The Wilkinson Microwave Anisotropy Probe (WMAP) spacecraft was launched in June of 2001. The sensor complement of WMAP consists of two Autonomous Star Trackers (ASTs), two Fine Sun Sensors (FSSs), and a gyro package which contains redundancy about one of the WMAP body axes. The onboard attitude estimation filter consists of an extended Kalman filter (EKF) solving for attitude and gyro bias errors which are then resolved into a spacecraft attitude quaternion and gyro bias. A pseudo-linear Kalman filter has been developed which directly estimates the spacecraft attitude quaternion, rate, and gyro bias. In this paper, the performance of the two filters is compared for the two major control modes of WMAP: inertial mode and observation mode.

  5. 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.

  6. Anisotropies in the gravitational wave background as a probe of the cosmic string network

    CERN Document Server

    Kuroyanagi, Sachiko; Yonemaru, Naoyuki; Kumamoto, Hiroki

    2016-01-01

    Pulsar timing arrays are one of the powerful tools to test the existence of cosmic strings through searching for the gravitational wave background. The amplitude of the background connects to information on cosmic strings such as the tension and string network properties. In addition, one may be able to extract more information on properties of cosmic strings by measuring anisotropies in the gravitational wave (GW) background. In this paper, we provide estimates of the level of anisotropy expected in the GW background generated by cusps on cosmic strings. We find that the anisotropy level strongly depends on the initial loop size $\\alpha$, and thus we may be able to put constraint on $\\alpha$ by measuring the anisotropy of the GW background. We also find that certain regions of the parameter space can be probed by shifting the observation frequency of GWs.

  7. Rotational Doppler Effect: A Probe for Molecular Orbitals Anisotropy.

    Science.gov (United States)

    Miao, Quan; Travnikova, Oksana; Gel'mukhanov, Faris; Kimberg, Victor; Sun, Yu-Ping; Thomas, T Darrah; Nicolas, Christophe; Patanen, Minna; Miron, Catalin

    2015-05-01

    The vibrationally resolved X-ray photoelectron spectra of X2Σg+(3σg−1) and B2Σu+(2σu−1) states of N2+ were recorded for different photon energies and orientations of the polarization vector. Clear dependencies of the spectral line widths on the X-ray polarization as well as on the symmetry of the final electronic states are observed. Contrary to the translational Doppler, the rotational Doppler broadening is sensitive to the photoelectron emission anisotropy. On the basis of theoretical modeling, we suggest that the different rotational Doppler broadenings observed for gerade and ungerade final states result from a Young's double-slit interference phenomenon. PMID:26263315

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

    CERN Document Server

    Furuya, Yu; Sendouda, Yuuiti

    2016-01-01

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

  9. Constraints on CPT violation from Wilkinson Microwave Anisotropy Probe three year polarization data: A wavelet analysis

    International Nuclear Information System (INIS)

    We perform a wavelet analysis of the temperature and polarization maps of the cosmic microwave background (CMB) delivered by the Wilkinson Microwave Anisotropy Probe experiment in search for a parity-violating signal. Such a signal could be seeded by new physics beyond the standard model, for which the Lorentz and CPT symmetries may not hold. Under these circumstances, the linear polarization direction of a CMB photon may get rotated during its cosmological journey, a phenomenon also called cosmological birefringence. Recently, Feng et al. have analyzed a subset of the Wilkinson Microwave Anisotropy Probe and BOOMERanG 2003 angular power spectra of the CMB, deriving a constraint that mildly favors a nonzero rotation. By using wavelet transforms we set a tighter limit on the CMB photon rotation angle Δα=-2.5±3.0 (Δα=-2.5±6.0) at the one (two) σ level, consistent with a null detection

  10. ANOMALOUS PARITY ASYMMETRY OF THE WILKINSON MICROWAVE ANISOTROPY PROBE POWER SPECTRUM DATA AT LOW MULTIPOLES

    International Nuclear Information System (INIS)

    We have investigated non-Gaussianity of our early universe by comparing the parity asymmetry of the Wilkinson Microwave Anisotropy Probe (WMAP) power spectrum with simulations. We find that odd-parity preference of the WMAP data (2 ≤ l ≤ 18) is anomalous at 4-in-1000 level. We find it likely that low quadrupole power is part of this parity asymmetry rather than an isolated anomaly. Further investigation is required to find out whether the origin of this anomaly is a cosmological or a systematic effect. The data from Planck Surveyor, which has systematics distinct from WMAP, will help us to resolve the origin of the anomalous odd-parity preference.

  11. 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; Burger, Bryce; Chervenak, Jay; Das, Sudeep; Devlin, Mark J.; Dicker, Simon R.; Bertrand Doriese, W.; Dunkley, Joanna; Dunner, Rolando; Essinger-Hileman, Thomas; Fisher, Ryan P.; Fowler, Joseph W.; Halpern, Mark; Hasselfield, Matthew; Moseley, Harvey; Wollack, Ed

    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.

  12. Anisotropies of Gravitational-Wave Standard Sirens as a New Cosmological Probe without Redshift Information.

    Science.gov (United States)

    Namikawa, Toshiya; Nishizawa, Atsushi; Taruya, Atsushi

    2016-03-25

    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, previously proposed cosmological 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, once GW observations will be well established in the future, (i) these anisotropies can be measured even at very high redshifts (z≥2), where the identification of the electromagnetic counterpart is difficult, (ii) the expected constraints on the primordial non-Gaussianity with the Einstein Telescope would be comparable to or even better than the other large-scale structure probes at the same epoch, and (iii) the cross-correlation with other cosmological observations is found to have high-statistical significance, providing additional cosmological information at very high redshifts. PMID:27058068

  13. 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.

  14. 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; Burger, Bryce; Chervenak, Jay; Das, Sudeep; Devlin, Mark J.; Dicker, Simon R.; Bertrand Doriese, W.; Dunkley, Joanna; Dunner, Rolando; Essinger-Hileman, Thomas; Fisher, Ryan P.; Fowler, Joseph W.; Halpern, Mark; Hasselfield, Matthew; Moseley, Harvey; Wollack, Ed

    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 < I < 1000, we determine the absolute calibration with an uncertainty of 2% in temperature. The precise measurement of the calibration error directly impacts the uncertainties in the 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.

  15. THE ATACAMA COSMOLOGY TELESCOPE: CALIBRATION WITH THE WILKINSON MICROWAVE ANISOTROPY PROBE USING CROSS-CORRELATIONS

    International Nuclear Information System (INIS)

    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 map-making 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 < l < 1000, we determine the absolute calibration with an uncertainty of 2% in temperature. The precise measurement of the calibration error directly impacts the uncertainties in the 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.

  16. A SEARCH FOR CONCENTRIC CIRCLES IN THE 7 YEAR WILKINSON MICROWAVE ANISOTROPY PROBE TEMPERATURE SKY MAPS

    International Nuclear Information System (INIS)

    In this Letter, we search for concentric circles with low variance in cosmic microwave background sky maps. The detection of such circles would hint at new physics beyond the current cosmological concordance model, which states that the universe is isotropic and homogeneous, and filled with Gaussian fluctuations. We first describe a set of methods designed to detect such circles, based on matched filters and χ2 statistics, and then apply these methods to the best current publicly available data, the 7 year Wilkinson Microwave Anisotropy Probe (WMAP) temperature sky maps. We compare the observations with an ensemble of 1000 Gaussian ΛCDM simulations. Based on these tests, we conclude that the WMAP sky maps are fully compatible with the Gaussian and isotropic hypothesis as measured by low-variance ring statistics.

  17. THE EFFECT OF ASYMMETRIC BEAMS IN THE WILKINSON MICROWAVE ANISOTROPY PROBE EXPERIMENT

    International Nuclear Information System (INIS)

    We generate simulations of the cosmic microwave background (CMB) temperature field as observed by the Wilkinson Microwave Anisotropy Probe (WMAP) satellite, taking into account the detailed shape of the asymmetric beams and scanning strategy of the experiment, and use these to re-estimate the WMAP beam transfer functions. This method avoids the need of artificially symmetrizing the beams, as done in the baseline WMAP approach, and instead measures the total convolution effect by direct simulation. We find only small differences with respect to the nominal transfer functions, typically less than 1% everywhere, and less than 0.5% at l s = 0.964 ± 0.014, corresponding to a negative shift of -0.1σ compared to the previously released WMAP results. Our CMB sky simulations are made publicly available and can be used for general studies of asymmetric beam effects in the WMAP data.

  18. The Microwave Anisotropy Probe (MAP) Guidance, Navigation, and Control Hardware Suite

    Science.gov (United States)

    Ward, David K.; Davis, Gary T.; O'Donnell, James R., Jr.

    2002-01-01

    The on-orbit success of the Microwave Anisotropy Probe (MAP) Guidance, Navigation, and Control System can partially be attributed to the performance of a hardware suite chosen to meet the complex attitude determination and control requirements of the mission. To meet these requirements, a diverse set of components was used. The set included two Lockheed Martin AST-201 star trackers, two Kearfott Two-Axis Rate Assemblies mounted to provide X, Y and redundant Z-axis rates, two Adcole Digital Sun Sensor heads sharing one set of electronics, twelve Adcole Coarse Sun Sensor eyes, three Ithaco E-sized Reaction Wheel Assemblies, a Propulsion Subsystem that employed eight Primex Rocket Engine Modules, and a pair of Goddard-designed Attitude Control Electronics which connect all of the components to the spacecraft processor. The performance of this hardware is documented, as are some of the spacecraft accommodations and lessons learned that came from working with this particular set of hardware.

  19. Brute force reconstruction of the primordial fluctuation spectrum from five-year Wilkinson Microwave Anisotropy Probe observations

    International Nuclear Information System (INIS)

    The primordial fluctuation spectrum is reconstructed from the five-year Wilkinson Microwave Anisotropy Probe data of the cosmic microwave background anisotropy. We divide the wave number space in the range of 1.23x10-3 Mpc-1 -2 Mpc-1 into about 50 bins, and derive probability distributions of fluctuation amplitudes on the respective scales using Monte Carlo simulations. Although the reconstructed spectrum is basically consistent with a power-law spectrum, we find a hint of fine structure at k≅0.002 Mpc-1 and 0.009 Mpc-1. The former is observed only in the temperature anisotropy, while the latter is both in the temperature and polarization anisotropies. The significance of these features are discussed, and it is shown that the deviation from a power-law spectrum at k≅0.009 Mpc-1 is at 2.8σ level.

  20. Anisotropy and probe-medium interactions in the microrheology of nematic fluids.

    Energy Technology Data Exchange (ETDEWEB)

    Cordoba, Andres; Stieger, Tillmann; Mazza, Marco G.; Schoen, Martin; de Pablo, Juan J.

    2016-01-01

    A theoretical formalism is presented to analyze and interpret microrheology experiments in anisotropic fluids with nematic order. The predictions of that approach are examined in the context of a simple coarse-grained molecular model which is simulated using nonequilibrium molecular dynamics calculations. The proposed formalism is used to study the effect of confinement, the type of anchoring at the probe-particle surface, and the strength of the nematic field on the rheological response functions obtained from probe-particle active microrheology. As expected, a stronger nematic field leads to increased anisotropy in the rheological response of the material. It is also found that the defect structures that arise around the probe particle, which are determined by the type of anchoring and the particle size, have a significant effect on the rheological response observed in microrheology simulations. Independent estimates of the bulk dynamic modulus of the model nematic fluid considered here are obtained from small-amplitude oscillatory shear simulations with Lees Edwards boundary conditions. The results of simulations indicate that the dynamic modulus extracted from particle-probe microrheology is different from that obtained in the absence of the particle, but that the differences decrease as the size of the defect also decreases. Importantly, the results of the nematic microrheology theory proposed here are in much closer agreement with simulations than those from earlier formalisms conceived for isotropic fluids. As such, it is anticipated that the theoretical framework advanced in this study could provide a useful tool for interpretation of microrheology experiments in systems such as liquid crystals and confined macromolecular solutions or gels.

  1. Mechanical anisotropy and adaptation of metastatic cells probed by magnetic microbeads

    Science.gov (United States)

    Zhang, Zhipeng; Shi, Yanhui; Jhiang, Sissy M.; Menq, Chia-Hsiang

    2010-02-01

    Metastatic cells have the ability to break through the basal lamina, enter the blood vessels, circulate through the vasculature, exit at distant sites, and form secondary tumors. This multi-step process, therefore, clearly indicates the inherent ability of metastatic cells to sense, process, and adapt to the mechanical forces in different surrounding environments. We describe a magnetic probing device that is useful in characterizing the mechanical properties of cells along arbitrary two-dimensional directions. Magnetic force, with the advantages of biocompatibility and specificity, was produced by magnetic poles placed in an octupole configuration and applied to fibronectin-coated magnetic microbeads attached on cell membrane. Cell deformation in response to the applied force was then recorded through the displacement of the microbeads. The motion of the beads was measured by computer processing the video images acquired by a high-speed CMOS camera. Rotating force vectors with constant magnitude while pointing to directions of all 360 degrees were applied to study the mechanical anisotropy of metastatic breast cancer cells MDA-MB-231. The temporal changes in magnitude and directionality of the cellular responses were then analyzed to investigate the cellular adaptation to force stimulation. This probing technology thus has the potential to provide us a better understanding of the mechano-signatures of cells.

  2. SIGNIFICANT FOREGROUND UNRELATED NON-ACOUSTIC ANISOTROPY ON THE 1 DEGREE SCALE IN WILKINSON MICROWAVE ANISOTROPY PROBE 5-YEAR OBSERVATIONS

    International Nuclear Information System (INIS)

    The spectral variation of the cosmic microwave background (CMB) as observed by WMAP was tested using foreground reduced WMAP5 data, by producing subtraction maps at the 1 deg. angular resolution between the two cosmological bands of V and W, for masked sky areas that avoid the Galactic disk. The resulting V - W map revealed a non-acoustic signal over and above the WMAP5 pixel noise, with two main properties. First, it possesses quadrupole power at the ∼1 μK level which may be attributed to foreground residuals. Second, it fluctuates also at all values of l> 2, especially on the 1 deg. scale (200 ∼< l ∼< 300). The behavior is random and symmetrical about zero temperature with an rms ∼7 μK, or 10% of the maximum CMB anisotropy, which would require a 'cosmic conspiracy' among the foreground components if it is a consequence of their existence. Both anomalies must be properly diagnosed and corrected if 'precision' cosmology is the claim. The second anomaly is, however, more interesting because it opens the question on whether the CMB anisotropy genuinely represents primordial density seeds.

  3. Inflation model constraints from the Wilkinson Microwave Anisotropy Probe three-year data

    Energy Technology Data Exchange (ETDEWEB)

    Kinney, William H.; /SUNY, Buffalo; Kolb, Edward W.; /Fermilab /Chicago U., Astron. Astrophys. Ctr.; Melchiorri, Alessandro; /Rome U. /INFN, Rome; Riotto, Antonio; /CERN

    2006-05-01

    We extract parameters relevant for distinguishing among single-field inflation models from the Wilkinson Microwave Anisotropy Probe (WMAP) three-year data set, and also from WMAP in combination with the Sloan Digital Sky Survey (SDSS) galaxy power spectrum. Our analysis leads to the following conclusions: (1) the Harrison-Zel'dovich model is consistent with both data sets at a 95% confidence level; (2) there is no strong evidence for running of the spectral index of scalar perturbations; (3) Potentials of the form V {infinity} {phi}{sup P} are consistent with the data for p = 2, and are marginally consistent with the WMAP data considered alone for p = 4, but ruled out by WMAP combined with SDSS. We perform a ''Monte Carlo reconstruction'' of the inflationary potential, and find that: (1) there is no evidence to support an observational lower bound on the amplitude of gravitational waves produced during inflation; (2) models such as simple hybrid potentials which evolve toward an inflationary late-time attractor in the space of flow parameters are strongly disfavored by the data, (3) models selected with even a weak slow-roll prior strongly cluster in the region favoring a ''red'' power spectrum and no running of the spectral index, consistent with simple single-field inflation models.

  4. IMPROVED CONSTRAINTS ON PRIMORDIAL NON-GAUSSIANITY FOR THE WILKINSON MICROWAVE ANISOTROPY PROBE 5-YEAR DATA

    International Nuclear Information System (INIS)

    We present constraints on the nonlinear coupling parameter fnl with the Wilkinson Microwave Anisotropy Probe (WMAP) data. We use an updated method based on the spherical Mexican hat wavelet (SMHW) which provides improved constraints on the fnl parameter. This paper is a continuation of a previous work by Curto et al., where several third-order statistics based on the SMHW were considered. In this paper, we use all the possible third-order statistics computed from the wavelet coefficient maps evaluated at 12 angular scales. The scales are logarithmically distributed from 6.9 arcmin to 500 arcmin. Our analysis indicates that fnl is constrained to -18 nl nl = 6 ± 5. Our result excludes at ∼99% CL the best-fitting value fnl = 87 reported by Yadav and Wandelt. We have also constrained fnl for the Q, V, and W frequency bands separately, finding compatibility with zero at 95% CL for the Q and V bands but not for the W band. We have performed some further tests to understand the cause of this deviation which indicate that systematics associated with the W radiometers could be responsible for this result. Finally, we have performed a Galactic north-south analysis for fnl. We have not found any asymmetry, i.e., the best-fitting fnl for the northern pixels is compatible with the best-fitting fnl for the southern pixels.

  5. Wilkinson Microwave Anisotropy Probe 7-yr constraints on fNL with a fast wavelet estimator

    CERN Document Server

    Casaponsa, B; Curto, A; Martínez-González, E; Vielva, P

    2010-01-01

    A new method to constrain the local non-linear coupling parameter fNL based on a fast wavelet decomposition is presented. Using a multiresolution wavelet adapted to the HEALPix pixelization, we have developed a method that is 10^2 times faster than previous estimators based on isotropic wavelets and 10^3 faster than the KSW bispectrum estimator, at the resolution of the Wilkinson Microwave Anisotropy Probe (WMAP) data. The method has been applied to the WMAP 7-yr V+W combined map, imposing constraints on fNL of -69 < fNL < 65 at the 95 per cent CL. This result has been obtained after correcting for the contribution of the residual point sources which has been estimated to be fNL = 7 +/- 6. In addition, a Gaussianity analysis of the data has been carried out using the third order moments of the wavelet coefficients, finding consistency with Gaussianity. Although the constrainsts imposed on fNL are less stringent than those found with optimal estimators, we believe that a very fast method, as the one prop...

  6. The Anisotropic Line Correlation Function as a Probe of Anisotropies in Galaxy Surveys

    CERN Document Server

    Eggemeier, Alexander; Smith, Robert E; Niemeyer, Jens

    2015-01-01

    We propose an anisotropic generalisation of the line correlation function (ALCF) to separate and quantify phase information in the large-scale structure of galaxies. The line correlation function probes the strictly non-linear regime of structure formation and since phase information drops out of the power spectrum, the line correlation function provides a complementary tool to commonly used techniques based on two-point statistics. Furthermore, it is independent of linear bias as well as the Gaussian variance on the modulus of the density field and thus may also prove to be advantageous compared to the bispectrum or similar higher-order statistics for certain cases. For future applications it is vital, though, to be able to account for observational effects that cause anisotropies in the distribution of galaxies. Based on a number of numerical studies, we find that our ALCF is well suited to accomplish this task and we demonstrate how the Alcock-Paczynski effect and kinematical redshift-space distortions can...

  7. The Microwave Anisotropy Probe (MAP): Guidance, Navigation, and Control Hardware Suite

    Science.gov (United States)

    Ward, David K.; Davis, Gary T.; Bauer, Frank H. (Technical Monitor)

    2002-01-01

    The Microwave Anisotropy Probe (MAP) was launched June 30, 2001 to create an all-sky map of the Cosmic Microwave Background. The mission's hardware suite included two Lockheed Martin AST-201 star trackers, two Kearfott Two-Axis Rate Assemblies (TARAs) mounted to provide X, Y and redundant Z-axis rates, two Adcole Digital Sun Sensor (DSS) heads sharing one set of electronics, twelve Adcole Coarse Sun Sensor (CSS) eyes, three Ithaco E-sized Reaction Wheel Assemblies (RWAs), and a Propulsion Subsystem that employed eight PRIMEX Rocket Engine Modules (REMs). This hardware has allowed MAP to meet its various Orbit and Attitude Control Requirements, including performing a complex zero-momentum scan, meeting its attitude determination requirements, and maintaining a trajectory that places MAP in a lissajous orbit around the second Sun-Earth Lagrange point (L2) via phasing loops and a lunar gravity assist. Details of MAP's attitude determination, attitude control, and trajectory design are presented separately. This paper will focus on the performance of the hardware components mentioned above, as well as the significant lessons learned through the use of these components. An emphasis will be placed on spacecraft design modifications that were needed to accommodate existing hardware designs into the MAP Observatory design.

  8. NINE-YEAR WILKINSON MICROWAVE ANISOTROPY PROBE (WMAP) OBSERVATIONS: FINAL MAPS AND RESULTS

    International Nuclear Information System (INIS)

    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 CMB maps are presented. We now implement an optimal C –1 weighting to compute the temperature angular power spectrum. The WMAP mission has resulted in a highly constrained ΛCDM 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 eff = 3.84 ± 0.40). The model fit also implies that the age of the universe is t 0 = 13.772 ± 0.059 Gyr, and the fit Hubble constant is H 0 = 69.32 ± 0.80 km s–1 Mpc–1. 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 (ns = 0.9608 ± 0.0080); and the universe is close to flat/Euclidean (Ωk = -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-parameter ΛCDM model, based

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

    International Nuclear Information System (INIS)

    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 ΩΛ, 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

  10. Nine-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Parameter Results

    Science.gov (United States)

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

    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 Lambda-CDM 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 Omega(sub b)h(exp 2), Omega(sub c)h(exp 2)and Omega(sub Lambda), are each determined to a precision of approx. 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 5 sigma 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 Lambda-CDM parameter space by a factor of 68,000 relative to pre-WMAP measurements. We investigate a number of data combinations and show that their Lambda-CDM 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 sub kappa) = (0.0027 (sub +0.0039) (sup -0.0038;) the summed mass of neutrinos is limited to Sigma M(sub nu) sub eff) = 3.84 +/- 0+/-40, when the full data are analyzed. The joint constraint on N(sub eff) and the primordial helium abundance, Y(sub 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

  11. 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; Komatsu, E.; Nolta, M. R.; Page, L.; Spergel, D. N.; Wollack, E.; Dunkley, J.; Kogut, A.; Limon,, M.; Meyer, S. S.; Tucker, G. S.; Wright, E. L.

    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

  12. NINE-YEAR WILKINSON MICROWAVE ANISOTROPY PROBE (WMAP) OBSERVATIONS: FINAL MAPS AND RESULTS

    Energy Technology Data Exchange (ETDEWEB)

    Bennett, C. L.; Larson, D.; Weiland, J. L. [Department of Physics and Astronomy, The Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218-2686 (United States); Jarosik, N.; Page, L. [Department of Physics, Jadwin Hall, Princeton University, Princeton, NJ 08544-0708 (United States); Hinshaw, G.; Halpern, M. [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1 (Canada); Odegard, N.; Hill, R. S. [ADNET Systems, Inc., 7515 Mission Drive, Suite A100, Lanham, MD 20706 (United States); Smith, K. M. [Perimeter Institute for Theoretical Physics, Waterloo, ON N2L 2Y5 (Canada); Gold, B. [School of Physics and Astronomy, University of Minnesota, 116 Church Street S.E., Minneapolis, MN 55455 (United States); Komatsu, E. [Max-Planck-Institut für Astrophysik, Karl-Schwarzschild Str. 1, D-85741 Garching (Germany); Nolta, M. R. [Canadian Institute for Theoretical Astrophysics, 60 St. George Street, University of Toronto, Toronto, ON M5S 3H8 (Canada); Spergel, D. N. [Department of Astrophysical Sciences, Peyton Hall, Princeton University, Princeton, NJ 08544-1001 (United States); Wollack, E.; Kogut, A. [Code 665, NASA/Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Dunkley, J. [Oxford Astrophysics, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH (United Kingdom); Limon, M. [Columbia Astrophysics Laboratory, 550 West 120th Street, Mail Code 5247, New York, NY 10027-6902 (United States); Meyer, S. S. [Departments of Astrophysics and Physics, KICP and EFI, University of Chicago, Chicago, IL 60637 (United States); Tucker, G. S., E-mail: cbennett@jhu.edu [Department of Physics, Brown University, 182 Hope Street, Providence, RI 02912-1843 (United States); and others

    2013-10-01

    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 CMB maps are presented. We now implement an optimal C {sup –1} weighting to compute the temperature angular power spectrum. The WMAP mission has resulted in a highly constrained ΛCDM 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 t {sub 0} = 13.772 ± 0.059 Gyr, and the fit Hubble constant is H {sub 0} = 69.32 ± 0.80 km s{sup –1} Mpc{sup –1}. 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 (Ω{sub k} = -0.0027{sup +0.0039}{sub -0.0038}). Overall, the WMAP mission has resulted in a reduction of the cosmological parameter volume by a factor

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

    Energy Technology Data Exchange (ETDEWEB)

    Hinshaw, G.; Halpern, M. [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1 (Canada); Larson, D.; Bennett, C. L.; Weiland, J. L. [Department of Physics and Astronomy, The Johns Hopkins University, 3400 N. Charles St., Baltimore, MD 21218-2686 (United States); Komatsu, E. [Max-Planck-Institut für Astrophysik, Karl-Schwarzschild Str. 1, D-85741 Garching (Germany); Spergel, D. N. [Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU, WPI), Todai Institutes for Advanced Study, University of Tokyo, Kashiwa 277-8583 (Japan); Dunkley, J. [Oxford Astrophysics, Denys Wilkinson Building, Keble Road, Oxford, OX1 3RH (United Kingdom); Nolta, M. R. [Canadian Institute for Theoretical Astrophysics, 60 St. George St., University of Toronto, Toronto, ON M5S 3H8 (Canada); Hill, R. S.; Odegard, N. [ADNET Systems, Inc., 7515 Mission Dr., Suite A100 Lanham, MD 20706 (United States); Page, L.; Jarosik, N. [Department of Physics, Jadwin Hall, Princeton University, Princeton, NJ 08544-0708 (United States); Smith, K. M. [Department of Astrophysical Sciences, Peyton Hall, Princeton University, Princeton, NJ 08544-1001 (United States); Gold, B. [University of Minnesota, School of Physics and Astronomy, 116 Church Street S.E., Minneapolis, MN 55455 (United States); Kogut, A.; Wollack, E. [Code 665, NASA/Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Limon, M. [Columbia Astrophysics Laboratory, 550 W. 120th St., Mail Code 5247, New York, NY 10027-6902 (United States); Meyer, S. S. [Departments of Astrophysics and Physics, KICP and EFI, University of Chicago, Chicago, IL 60637 (United States); Tucker, G. S., E-mail: hinshaw@physics.ubc.ca [Department of Physics, Brown University, 182 Hope St., Providence, RI 02912-1843 (United States); and others

    2013-10-01

    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 {sub b} h {sup 2}, Ω {sub c} h {sup 2}, and Ω{sub 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 < 0.13 (95% CL); the spatial curvature parameter is limited to Ω{sub k} = -0.0027{sup +0.0039}{sub -0.0038}; the summed mass of neutrinos is limited to Σm {sub ν} < 0.44 eV (95% CL); and the number of relativistic species is found to lie within N {sub eff} = 3.84 ± 0.40, when the full data are analyzed. The joint constraint on N {sub eff} and the primordial helium abundance, Y {sub 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

  14. 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.; Meyer, S.S.; Tucker, G.S.; Wright, E.L.

    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

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

    Science.gov (United States)

    Hill, Michael D.; Herrera, Acey A.; Crane, J. Allen; Packard, Edward A.; Aviado, Carlos; Sampler, Henry P.; Obenschain, Arthur (Technical Monitor)

    2000-01-01

    The Microwave Anisotropy Probe (MAP) Observatory, scheduled for a late 2000 launch, is designed to measure temperature fluctuations (anisotropy) and produce a high sensitivity and high spatial resolution (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 PG measurements met the desired requirements, enabling the desired deformations to be measured and even resolved to 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.

  16. STAR FORMATION IN MASSIVE CLUSTERS VIA THE WILKINSON MICROWAVE ANISOTROPY PROBE AND THE SPITZER GLIMPSE SURVEY

    International Nuclear Information System (INIS)

    We use the Wilkinson Microwave Anisotropy Probe (WMAP) maximum entropy method foreground emission map combined with previously determined distances to giant H II regions to measure the free-free flux at Earth and the free-free luminosity of the Galaxy. We find a total flux fν = 54, 211 Jy and a flux from 88 sources of fν = 36, 043 Jy. The bulk of the sources are at least marginally resolved, with mean radii ∼60 pc, electron density ne ∼ 9 cm-3, and filling factor ΦHII∼0.005 (over the Galactic gas disk). The total dust-corrected ionizing photon luminosity is Q = 3.2 x 1053 ± 5.1 x 1052 photons s-1, in good agreement with previous estimates. We use GLIMPSE and Midcourse Space Experiment (MSX) 8 μm images to show that the bulk of the free-free luminosity is associated with bubbles having radii r ∼ 5-100 pc, with a mean of ∼20 pc. These bubbles are leaky, so that ionizing photons emitted inside the bubble escape and excite free-free emission beyond the bubble walls, producing WMAP sources that are larger than the 8 μm bubbles. We suggest that the WMAP sources are the counterparts of the extended low density H II regions described by Mezger. The 18 most luminous WMAP sources emit half the total Galactic ionizing flux. These 18 sources have 4 x 1051 s-1 ∼52 s-1, corresponding to 6 x 104 Msun ∼* ∼5 Msun; half to two thirds of this will be in the central massive star cluster. We convert the measurement of Q to a Galactic star formation rate (SFR) M-dot*=1.3±0.2 Msun yr-1, where the errors reflect only the error in free-free luminosity. We point out, however, that our inferred M-dot* is highly dependent on the exponent Γ ∼ 1.35 of the high-mass end of the stellar initial mass function. For 1.21 sun yr-1 * sun yr-1. We also determine a SFR of 0.14 Msun yr-1 for the Large Magellanic Cloud and 0.015 Msun yr-1 for the Small Magellanic Cloud.

  17. Direct probe of anisotropy in atom-molecule collisions via quantum scattering resonances

    CERN Document Server

    Klein, Ayelet; Skomorowski, Wojciech; Żuchowski, Piotr S; Pawlak, Mariusz; Janssen, Liesbeth M C; Moiseyev, Nimrod; van de Meerakker, Sebastiaan Y T; van der Avoird, Ad; Koch, Christiane P; Narevicius, Edvardas

    2016-01-01

    Anisotropy is a fundamental property of particle interactions. It occupies a central role in cold and ultra-cold molecular processes, where long range forces have been found to significantly depend on orientation in ultra-cold polar molecule collisions. Recent experiments have demonstrated the emergence of quantum phenomena such as scattering resonances in the cold collisions regime due to quantization of the intermolecular degrees of freedom. Although these states have been shown to be sensitive to interaction details, the effect of anisotropy on quantum resonances has eluded experimental observation so far. Here, we directly measure the anisotropy in atom-molecule interactions via quantum resonances by changing the quantum state of the internal molecular rotor. We observe that a quantum scattering resonance at a collision energy of $k_B$ x 270 mK appears in the Penning ionization of molecular hydrogen with metastable helium only if the molecule is rotationally excited. We use state of the art ab initio and ...

  18. Small-scale cosmic microwave background anisotropies as probe of the geometry of the universe

    Science.gov (United States)

    Kamionkowski, Marc; Spergel, David N.; Sugiyama, Naoshi

    1994-01-01

    We perform detailed calculations of cosmic microwave background (CMB) anisotropies in a cold dark matter (CDM)-dominated open universe with primordial adiabatic density perturbations for a variety of reionization histories. The CMB anisotropies depend primarily on the geometry of the universe, which in a matter-dominated universe is determined by Omega and the optical depth to the surface of last scattering. In particular, the location on the primary Doppler peak depends primarily on Omega and is fairly insensitive to the other unknown parameters, such as Omega(sub b), h, Lambda, and the shape of the power spectrum. Therefore, if the primordial density perturbations are adiabatic, measurements of CMB anisotropies on small scales may be used to determine Omega.

  19. Direct probe of anisotropy in atom-molecule collisions via quantum scattering resonances

    OpenAIRE

    Klein, Ayelet; Shagam, Yuval; Skomorowski, Wojciech; Żuchowski, Piotr. S.; Pawlak, Mariusz; Janssen, Liesbeth M. C.; Moiseyev, Nimrod; van de Meerakker, Sebastiaan Y. T.; van der Avoird, Ad; Koch, Christiane P.; Narevicius, Edvardas

    2016-01-01

    Anisotropy is a fundamental property of particle interactions. It occupies a central role in cold and ultra-cold molecular processes, where long range forces have been found to significantly depend on orientation in ultra-cold polar molecule collisions. Recent experiments have demonstrated the emergence of quantum phenomena such as scattering resonances in the cold collisions regime due to quantization of the intermolecular degrees of freedom. Although these states have been shown to be sensi...

  20. Thermal Reflector System Design and Testing for the Microwave Anisotropy Probe

    OpenAIRE

    Neubert, Hans; Chen, Wayne

    2000-01-01

    Scheduled for a June 2001 launch, the Microwave Anisotropy Probe’s (MAP) mission is to study in detail the cosmic microwave background radiation temperature fluctuations of the universe. The cosmic microwave background is the remnant afterglow of the Big Bang, and the tiny temperature differences from place to place on the sky provides a wealth of information about the basic nature of our universe. The observatory consists of dual back-to-back Gregorian optics and dual differential pseudo-cor...

  1. In-vivo Mapping of Human Skin Anisotropy Using Multi-directional Ultrasonic Probe

    Czech Academy of Sciences Publication Activity Database

    Tokar, Daniel; Hradilová, Jana; Převorovský, Zdeněk

    Praha: ČVUT Praha Fakulta jaderná a fyzikálně inženýrská, 2013 - (Hobza, T.), s. 165-172 ISBN 978-80-01-05383-6. [SPMS 2013. Nebřich (CZ), 24.06.2013-29.06.2013] Institutional support: RVO:61388998 Keywords : anisotropy * human skin in-vivo * ultrasonic testing * viscoelasticity Subject RIV: BO - Biophysics

  2. Statistical anisotropy of CMB as a probe of conformal rolling scenario

    CERN Document Server

    Ramazanov, S R

    2012-01-01

    Search for the statistical anisotropy in the CMB data is a powerful tool for constraining models of the early Universe. In this paper we focus on the recently proposed cosmological scenario with conformal rolling. We consider two sub-scenarios, one of which involves a long intermediate stage between conformal rolling and conventional hot epoch. Primordial scalar perturbations generated within these sub-scenarios have different direction-dependent power spectra, both characterized by a single parameter h^2. We search for the signatures of this anisotropy in the seven-year WMAP data using quadratic maximum likelihood method, first applied for similar purposes by Hanson and Lewis. We confirm the large quadrupole anisotropy detected in V and W bands, which has been argued to originate from systematic effects rather than from cosmology. We construct an estimator for the parameter h^2. In the case of the sub-scenario with the intermediate stage we set an upper limit h^2 < 0.045 at the 95% confidence level. The c...

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

    Science.gov (United States)

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

    2010-01-01

    We present new full-sky temperature and polarization maps in five frequency bands from 23 to 94 GHz, based on data from the first five years of the Wilkinson Microwave Anisotropy Probe (WMAP) sky survey. The new maps are consistent with previous maps and are more sensitive. The five-year maps incorporate several improvements in data processing made possible by the additional years of data and by a more complete analysis of the instrument calibration and in-flight beam response. We present several new tests for systematic errors in the polarization data and conclude that W-band polarization data is not yet suitable for cosmological studies, but we suggest directions for further study. We do find that Ka-band data is suitable for use; in conjunction with the additional years of data, the addition of Ka band to the previously used Q- and V-band channels significantly reduces the uncertainty in the optical depth parameter, tau. Further scientific results from the five-year data analysis are presented in six companion papers and are summarized in Section 7 of this paper. With the five-year WMAP data, we detect no convincing deviations from the minimal six-parameter ACDM model: a flat universe dominated by a cosmological constant, with adiabatic and nearly scale-invariant Gaussian fluctuations. Using WMAP data combined with measurements of Type Ia supernovae and Baryon Acoustic Oscillations in the galaxy distribution, we find (68% CL uncertainties): OMEGA(sub b)h(sup 2) = 0.02267(sup +0.00058)(sub -0.00059), OMEGA(sub c)h(sup 2) = 0.1131 plus or minus 0.0034, OMEGA(sub logical and) = 0.726 plus or minus 0.015, ns = .960 plus or minus 0.013, tau = 0.84 plus or minus 0.016, and DELTA(sup 2)(sub R) = (22.445 plus or minus 0.096) x 10(exp -9) at k = 0.002 Mpc(exp -1). From these we derive sigma(sub 8) = 0.812 plus or minus 0.026, H(sub 0) = 70.5 plus or minus 1.3 kilometers per second Mpc(exp -1), OMEGA(sub b) = 0.0456 plus or minus 0.0015, OMEGA(sub c) = .228 plus or minus

  4. Faraday rotation limits on a primordial magnetic field from Wilkinson Microwave Anisotropy Probe five-year data

    International Nuclear Information System (INIS)

    A primordial magnetic field in the early universe will cause Faraday rotation of the linear polarization of the cosmic microwave background generated via Compton scattering at the surface of last scattering. This rotation induces a nonzero parity-odd (B-mode) polarization component. The Wilkinson Microwave Anisotropy Probe 5-year data puts an upper limit on the magnitude of the B-polarization power spectrum; assuming that the B-polarization signal is totally due to the Faraday rotation effect, the upper limits on the comoving amplitude of a primordial stochastic magnetic field range from 6x10-8 to 2x10-6 G on a comoving length scale of 1 Mpc, depending on the power spectrum of the magnetic field.

  5. CROSS-POWER SPECTRUM AND ITS APPLICATION ON WINDOW FUNCTIONS IN THE WILKINSON MICROWAVE ANISOTROPY PROBE DATA

    International Nuclear Information System (INIS)

    The cross-power spectrum is a quadratic estimator between two maps that can provide unbiased estimate of the underlying power spectrum of the correlated signals, which is therefore used for extracting the power spectrum in the Wilkinson Microwave Anisotropy Probe (WMAP) data. In this paper, we discuss the limit of the cross-power spectrum and derive the residual from the uncorrelated signal, which is the source of error in power spectrum extraction. We employ the estimator to extract window functions by crossing pairs of extragalactic point sources. We demonstrate its usefulness in WMAP difference assembly maps where the window functions are measured via Jupiter and then extract the window functions of the five WMAP frequency band maps.

  6. Ultrafast magneto-photocurrents as probe of anisotropy relaxation in GaAs

    CERN Document Server

    Schmidt, Christian B; Pierz, Klaus; Bieler, Mark

    2016-01-01

    We induce ultrafast photocurrents in a GaAs crystal exposed to a magnetic field by optical femtosecond excitation. The magneto-photocurrents are studied by time-resolved detection of the simultaneously emitted THz radiation. We find that their dynamics differ considerably from the dynamics of other photocurrents which are expected to follow the temporal shape of the optical intensity. We attribute this difference to the influence of carrier-anisotropy relaxation on the magneto-photocurrents. Our measurements show that the anisotropy relaxation for carrier densities ranging between $10^{16}$ cm$^{-3}$ and $5 \\times 10^{17}$ cm$^{-3}$ occurs on two different time scales. While the slow time constant is approximately 100 fs long and most likely governed by electron-phonon scattering, the fast time constant is on the order of 10 fs and presumably linked to the valence band. Our studies not only help to better understand the microscopic origins of optically induced currents but - being even more important - show t...

  7. Angular Anisotropies in the Cosmic Gamma-ray Background as a Probe of its Origin

    OpenAIRE

    Miniati, Francesco; Koushiappas, Savvas M.; Di Matteo, Tiziana

    2007-01-01

    Notwithstanding the advent of the Gamma-ray Large Area Telescope, theoretical models predict that a significant fraction of the cosmic gamma-ray background (CGB), at the level of 20% of the currently measured value, will remain unresolved. The angular power spectrum of intensity fluctuations of the CGB contains information on its origin. We show that probing the latter from a few tens of arcmin to several degree scales, together with complementary GLAST observations of gamma-ray emission from...

  8. Strain-driven Anisotropy in Multiferroic Composites Probed with Soft X-ray Techniques

    International Nuclear Information System (INIS)

    Full text: Artificial multiferroic systems, in which novel properties emerge from elastic coupling between piezoelectric and magnetostrictive phases, show promise as a route to obtain room temperature magneto-electric coupling. We have used soft X-ray photoemission electron microscopy (X-PEEM) to determine the influence of piezoelectric-ferroelectric BaTiO3 (BTO) on the magnetic properties of magnetostrictive ferrimagnetic CoFe2O4 and NiFe2O4 thin films. Circular and linear dichroism spectromicroscopy gives insight into the magneto-electric interaction in a model system of a BTO substrate with an epitaxial spinel cap layer. An induced dichroism in the ferrimagnetic films is structural in origin and directly corresponds to the ferroelectric domain structure of the BTO substrate as imaged at both the Ti L2,3 edges of BTO and the Fe L2,3 edges of the film. Temperature, angular, and polarization dependent studies reveal this strain-induced effect strongly influences the magnetic anisotropy of individual 250 nm wide magnetic domains of the spinel films. (author)

  9. Nine-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Parameter Results

    CERN Document Server

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

    2012-01-01

    We present cosmological parameter constraints based on the final nine-year WMAP data, in conjunction with additional cosmological data sets. The WMAP data alone, and in combination, continue to be remarkably well fit by a six-parameter LCDM model. When WMAP data are combined with measurements of the high-l CMB anisotropy, the BAO scale, and the Hubble constant, the densities, Omegabh2, Omegach2, and Omega_L, 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 5sigma 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 LCDM parameter space by a factor of 68,000 relative to pre-WMAP measurements. We investigate a number of data combinations and show that their LCDM parameter fits are consistent. New limits on deviations from the six-parameter model are p...

  10. Angular Anisotropies in the Cosmic Gamma-ray Background as a Probe of its Origin

    CERN Document Server

    Miniati, Francesco; Di Matteo, Tiziana

    2007-01-01

    Notwithstanding the advent of the Gamma-ray Large Area Telescope, theoretical models predict that a significant fraction of the cosmic gamma-ray background (CGB), at the level of 20% of the currently measured value, will remain unresolved. The angular power spectrum of intensity fluctuations of the CGB contains information on its origin. We show that probing the latter from a few tens of arcmin to several degree scales, together with complementary GLAST observations of gamma-ray emission from galaxy clusters and the blazars luminosity function, can discriminate between a background that originates from unresolved blazars or cosmic rays accelerated at structure formation shocks.

  11. Angular Anisotropies in the Cosmic Gamma-Ray Background as a Probe of Its Origin

    Science.gov (United States)

    Miniati, Francesco; Koushiappas, Savvas M.; Di Matteo, Tiziana

    2007-09-01

    Notwithstanding the advent of the Gamma-ray Large Area Space Telescope, theoretical models predict that a significant fraction of the cosmic γ-ray background (CGB), at a level of 20% of the currently measured value, will remain unresolved. The angular power spectrum of intensity fluctuations of the CGB contains information on its origin. We show that probing the latter on scales from a few tens of arcminutes to several degrees, together with complementary GLAST observations of γ-ray emission from galaxy clusters and the blazar luminosity function, can discriminate between a background that originates from unresolved blazars or cosmic rays accelerated at structure formation shocks.

  12. SEVEN-YEAR WILKINSON MICROWAVE ANISOTROPY PROBE (WMAP ) OBSERVATIONS: ARE THERE COSMIC MICROWAVE BACKGROUND ANOMALIES?

    International Nuclear Information System (INIS)

    statistical combination of the full-sky anisotropy fluctuations. It may be due, in part, to chance alignments between the primary and secondary anisotropy, but this only shifts the coincidence from within the last scattering surface to between it and the local matter density distribution. While this alignment appears to be remarkable, there was no model that predicted it, nor has there been a model that provides a compelling retrodiction. We examine claims of a hemispherical or dipole power asymmetry across the sky and find that the evidence for these claims is not statistically significant. We confirm the claim of a strong quadrupolar power asymmetry effect, but there is considerable evidence that the effect is not cosmological. The likely explanation is an insufficient handling of beam asymmetries. We conclude that there is no compelling evidence for deviations from the ΛCDM model, which is generally an acceptable statistical fit to WMAP and other cosmological data

  13. Seven-year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Are There Cosmic Microwave Background Anomalies?

    Science.gov (United States)

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

    2011-02-01

    statistical combination of the full-sky anisotropy fluctuations. It may be due, in part, to chance alignments between the primary and secondary anisotropy, but this only shifts the coincidence from within the last scattering surface to between it and the local matter density distribution. While this alignment appears to be remarkable, there was no model that predicted it, nor has there been a model that provides a compelling retrodiction. We examine claims of a hemispherical or dipole power asymmetry across the sky and find that the evidence for these claims is not statistically significant. We confirm the claim of a strong quadrupolar power asymmetry effect, but there is considerable evidence that the effect is not cosmological. The likely explanation is an insufficient handling of beam asymmetries. We conclude that there is no compelling evidence for deviations from the ΛCDM model, which is generally an acceptable statistical fit to WMAP and other cosmological data. WMAP is the result of a partnership between Princeton University and NASA's Goddard Space Flight Center. Scientific guidance is provided by the WMAP Science Team.

  14. SEVEN-YEAR WILKINSON MICROWAVE ANISOTROPY PROBE (WMAP ) OBSERVATIONS: SKY MAPS, SYSTEMATIC ERRORS, AND BASIC RESULTS

    International Nuclear Information System (INIS)

    New full-sky temperature and polarization maps based on seven years of data from WMAP are presented. The new results are consistent with previous results, but have improved due to reduced noise from the additional integration time, improved knowledge of the instrument performance, and improved data analysis procedures. The improvements are described in detail. The seven-year data set is well fit by a minimal six-parameter flat ΛCDM model. The parameters for this model, using the WMAP data in conjunction with baryon acoustic oscillation data from the Sloan Digital Sky Survey and priors on H0 from Hubble Space Telescope observations, are Ωb h 2 = 0.02260 ± 0.00053, Ωc h 2 = 0.1123 ± 0.0035, ΩΛ = 0.728+0.015-0.016, ns = 0.963 ± 0.012, τ = 0.087 ± 0.014, and σ8 = 0.809 ± 0.024 (68% CL uncertainties). The temperature power spectrum signal-to-noise ratio per multipole is greater that unity for multipoles l ∼m h 2 = 0.1334+0.0056-0.0055, and the epoch of matter-radiation equality, zeq = 3196+134-133, using WMAP data alone. The new WMAP data, when combined with smaller angular scale microwave background anisotropy data, result in a 3σ detection of the abundance of primordial helium, YHe = 0.326 ± 0.075. When combined with additional external data sets, the WMAP data also yield better determinations of the total mass of neutrinos, ΣMν ≤ 0.58 eV(95%CL), and the effective number of neutrino species, Neff = 4.34+0.86-0.88. The power-law index of the primordial power spectrum is now determined to be ns = 0.963 ± 0.012, excluding the Harrison-Zel'dovich-Peebles spectrum by >3σ. These new WMAP measurements provide important tests of big bang cosmology.

  15. Local structure and magnetism of L10-type FeNi alloy films with perpendicular magnetic anisotropy studied through 57Fe nuclear probes

    International Nuclear Information System (INIS)

    The local structure and magnetism of FeNi alloy films prepared by alternate deposition of Fe and Ni monatomic layers, where perpendicular magnetic anisotropy has been observed, were investigated through 57Fe nuclear probes using Mössbauer spectroscopy. It was confirmed that the films are composed of L10-type ordered FeNi phase and A1-type disordered FeNi phase. For the films grown at 40–70 °C, which have no perpendicular anisotropy, the A1-disordered phase is dominant, whereas for the films grown at 100–190 °C, which have a stronger perpendicular anisotropy, the relative amount of the L10-ordered phase reaches 40% or more. It was clearly shown that the magnetic anisotropy of these films is strongly correlated with the local environments of Fe in the films. The results imply that if a further increase in the ratio of the L10-ordered phase is successfully achieved, one would obtain films with a stronger magnetic anisotropy applicable to perpendicular magnetic recording. (paper)

  16. SPINNING DUST EMISSION: EFFECTS OF IRREGULAR GRAIN SHAPE, TRANSIENT HEATING, AND COMPARISON WITH WILKINSON MICROWAVE ANISOTROPY PROBE RESULTS

    International Nuclear Information System (INIS)

    Planck is expected to answer crucial questions on the early universe, but it also provides further understanding on anomalous microwave emission. Electric dipole emission from spinning dust grains continues to be the favored interpretation of anomalous microwave emission. In this paper, we present a method to calculate the rotational emission from small grains of irregular shape with moments of inertia I1 ≥ I2 ≥ I3. We show that a torque-free rotating irregular grain with a given angular momentum radiates at multiple frequency modes. The resulting spinning dust spectrum has peak frequency and emissivity increasing with the degree of grain shape irregularity, which is defined by I1:I2:I3. We discuss how the orientation of the dipole moment μ in body coordinates affects the spinning dust spectrum for different regimes of internal thermal fluctuations. We show that the spinning dust emissivity for the case of strong thermal fluctuations is less sensitive to the orientation of μ than in the case of weak thermal fluctuations. We calculate spinning dust spectra for a range of gas density and dipole moment. The effect of compressible turbulence on spinning dust emission is investigated. We show that the emission in a turbulent medium increases by a factor from 1.2 to 1.4 relative to that in a uniform medium, as the sonic Mach number Ms increases from 2 to 7. Finally, spinning dust parameters are constrained by fitting our improved model to five-year Wilkinson Microwave Anisotropy Probe cross-correlation foreground spectra, for both the Hα-correlated and 100-μm-correlated emission spectra.

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

    International Nuclear Information System (INIS)

    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.

  18. EVOLUTION OF THE COSMIC MICROWAVE BACKGROUND POWER SPECTRUM ACROSS WILKINSON MICROWAVE ANISOTROPY PROBE DATA RELEASES: A NONPARAMETRIC ANALYSIS

    International Nuclear Information System (INIS)

    Using a nonparametric function estimation methodology, we present a comparative analysis of the Wilkinson Microwave Anisotropy Probe (WMAP) 1-, 3-, 5-, and 7-year data releases for the cosmic microwave background (CMB) angular power spectrum with respect to the following key questions. (1) How well is the power spectrum determined by the data alone? (2) How well is the ΛCDM model supported by a model-independent, data-driven analysis? (3) What are the realistic uncertainties on peak/dip locations and heights? Our results show that the height of the power spectrum is well determined by data alone for multipole l approximately less than 546 (1-year), 667 (3-year), 804 (5-year), and 842 (7-year data). We show that parametric fits based on the ΛCDM model are remarkably close to our nonparametric fits in l-regions where data are sufficiently precise. In contrast, the power spectrum for an HΛCDM model is progressively pushed away from our nonparametric fit as data quality improves with successive data realizations, suggesting incompatibility of this particular cosmological model with respect to the WMAP data sets. We present uncertainties on peak/dip locations and heights at the 95% (2σ) level of confidence and show how these uncertainties translate into hyperbolic 'bands' on the acoustic scale (lA ) and peak shift (φm) parameters. Based on the confidence set for the 7-year data, we argue that the low-l upturn in the CMB power spectrum cannot be ruled out at any confidence level in excess of about 10% (≈0.12σ). Additional outcomes of this work are a numerical formulation for minimization of a noise-weighted risk function subject to monotonicity constraints, a prescription for obtaining nonparametric fits that are closer to cosmological expectations on smoothness, and a method for sampling cosmologically meaningful power spectrum variations from the confidence set of a nonparametric fit.

  19. Real space tests of the statistical isotropy and Gaussianity of the Wilkinson Microwave Anisotropy Probe cosmic microwave background data

    International Nuclear Information System (INIS)

    We introduce and analyze a method for testing statistical isotropy and Gaussianity and apply it to the Wilkinson Microwave Anisotropy Probe (WMAP) cosmic microwave background (CMB) foreground reduced temperature maps. We also test cross-channel difference maps to constrain levels of residual foreground contamination and systematic uncertainties. We divide the sky into regions of varying size and shape and measure the first four moments of the one-point distribution within these regions, and using their simulated spatial distributions we test the statistical isotropy and Gaussianity hypotheses. By randomly varying orientations of these regions, we sample the underlying CMB field in a new manner, that offers a richer exploration of the data content, and avoids possible biasing due to a single choice of sky division. In our analysis we account for all two-point correlations between different regions and also show the impact on the results when these correlations are neglected. The statistical significance is assessed via comparison with realistic Monte Carlo simulations. We find the three-year WMAP maps to agree well with the isotropic, Gaussian random field simulations as probed by regions corresponding to the angular scales ranging from 6° to 30° at 68% confidence level (CL). We report a strong, anomalous (99.8% CL) dipole 'excess' in the V band of the three-year WMAP data and also in the V band of the WMAP five-year data (99.3% CL). Using our statistics, we notice large scale hemispherical power asymmetry, and find that it is not highly statistically significant in the WMAP three-year data (≲97%) at scales l≤40. The significance is even smaller if multipoles up to l=1024 are considered (∼90% CL). We give constraints on the amplitude of the previously proposed CMB dipole modulation field parameter. We find some hints of foreground contamination in the form of a locally strong, anomalous kurtosis excess in the Q+V +W co-added map, which however is not

  20. DETECTION OF ANOMALOUS MICROWAVE EMISSION IN THE PLEIADES REFLECTION NEBULA WITH WILKINSON MICROWAVE ANISOTROPY PROBE AND THE COSMOSOMAS EXPERIMENT

    International Nuclear Information System (INIS)

    We present evidence for anomalous microwave emission (AME) in the Pleiades reflection nebula, using data from the seven-year release of the Wilkinson Microwave Anisotropy Probe and from the COSMOSOMAS (Cosmological Structures on Medium Angular Scales) experiment. The flux integrated in a 1° radius around R.A. = 56.024, decl. = 23.078 (J2000) is 2.15 ± 0.12 Jy at 22.8 GHz, where AME is dominant. COSMOSOMAS data show no significant emission, but allow one to set upper limits of 0.94 and 1.58 Jy (99.7% confidence level), respectively, at 10.9 and 14.7 GHz, which are crucial to pin down the AME spectrum at these frequencies, and to discard any other emission mechanisms which could have an important contribution to the signal detected at 22.8 GHz. We estimate the expected level of free-free emission from an extinction-corrected Hα template, while the thermal dust emission is characterized from infrared DIRBE data and extrapolated to microwave frequencies. When we deduct the contribution from these two components at 22.8 GHz, the residual flux, associated with AME, is 2.12 ± 0.12 Jy (17.7σ). The spectral energy distribution from 10 to 60 GHz can be accurately fitted with a model of electric dipole emission from small spinning dust grains distributed in two separated phases of molecular and atomic gas, respectively. The dust emissivity, calculated by correlating the 22.8 GHz data with 100 μm data, is found to be 4.36 ± 0.17 μK (MJy sr–1)–1, a value considerably lower than in typical AME clouds, which present emissivities of ∼20 μK (MJy sr–1)–1, although higher than the 0.2 μK (MJy sr–1)–1 of the translucent cloud LDN 1780, where AME has recently been claimed. The physical properties of the Pleiades nebula, in particular its low extinction AV ∼ 0.4, indicate that this is indeed a much less opaque object than those where AME has usually been studied. This fact, together with the broad knowledge of the stellar content of this region, provides an

  1. Anisotropy of weakly vibrated granular flows.

    Science.gov (United States)

    Wortel, Geert H; van Hecke, Martin

    2015-10-01

    We experimentally probe the anisotropy of weakly vibrated flowing granular media. Depending on the driving parameters-flow rate and vibration strength-this anisotropy varies significantly. We show how the anisotropy collapses when plotted as a function of the driving stresses, uncovering a direct link between stresses and anisotropy. Moreover, our data suggest that for small anisotropies, the shear stresses vanish. Anisotropy of the fabric of granular media thus plays a crucial role in determining the rheology of granular flows. PMID:26565148

  2. Anisotropy of Weakly Vibrated Granular Flows

    OpenAIRE

    Wortel, Geert; Van Hecke, Martin

    2014-01-01

    We experimentally probe the anisotropy of the fabric of weakly vibrated, flowing granular media. Depending on the driving parameters --- flow rate and vibration strength --- this anisotropy varies significantly. We show how the anisotropy collapses when plotted as function of the driving stresses, uncovering a direct link between stresses and anisotropy. Moreover, our data suggests that for small anisotropies, the shear stresses vanish. Anisotropy of the fabric of granular media thus plays a ...

  3. Magnetic anisotropy of the Kondo lattice CePd1-xRhx probed with polarized neutrons

    International Nuclear Information System (INIS)

    We have investigated the magnetic anisotropy of the Kondo lattice system CePd1-xRhx at low temperatures by using polarized neutrons at the instrument POLI-HEIDI where the polarization analysis device CryoPad has been installed recently. The system CePd1-xRhx shows significant anisotropy for low Rh concentrations xC(x) changes sign at Rh concentration x=0.65 and a cluster glass phase emerges. Our data are consistent with previous measurements of the magnetisation. The measured polarization matrices allows us to quantify the average domain size in each direction of space and give us important hints of magnetic stray fields of the sample induced even in zero external magnetic field.

  4. MICROWAVE EMISSION FROM THE EDGEWORTH-KUIPER BELT AND THE ASTEROID BELT CONSTRAINED FROM THE WILKINSON MICROWAVE ANISOTROPY PROBE

    International Nuclear Information System (INIS)

    Objects in the Edgeworth-Kuiper Belt and the main asteroid belt should emit microwaves that may give rise to extra anisotropy signals in the multipole of the cosmic microwave background (CMB) experiment. Constraints are derived from the absence of positive detection of such anisotropies for l ∼+. This limit is consistent with the mass extrapolated from the observable population with the size of a ∼> 15 km, assuming that the small-object population follows the power law in size dN/da ∼ a-q with the canonical index expected for collisional equilibrium, q ≅ 3.5, with which 23% of the mass is ascribed to objects smaller than are observationally accessible down to grains. A similar argument applied to the main asteroid belt indicates that the grain population should not increase more quickly than q ≅ 3.6 toward smaller radii, if the grain population follows the power law that continues to observed asteroids with larger radii. Both cases are at or only slightly above the limit that can be physically significant, implying the importance of further tightening the CMB anisotropy limit, which may be attained with observation at higher radio frequencies.

  5. THE CONTRIBUTION OF THE KINEMATIC SUNYAEV-ZEL'DOVICH EFFECT FROM THE WARM-HOT INTERGALACTIC MEDIUM TO THE FIVE-YEAR WILKINSON MICROWAVE ANISOTROPY PROBE DATA

    International Nuclear Information System (INIS)

    We study the contribution of the kinematic Sunyaev-Zel'dovich (kSZ) effect, generated by the warm-hot intergalactic medium, to the cosmic microwave background temperature anisotropies in the five-year Wilkinson Microwave Anisotropy Probe (WMAP) data. We explore the concordance ΛCDM cosmological model, with and without this kSZ contribution, using a Markov chain Monte Carlo algorithm. Our model requires a single extra parameter to describe this new component. Our results show that the inclusion of the kSZ signal improves the fit to the data without significantly altering the best-fit cosmological parameters except Ωb h 2. The improvement is localized at the l ∼> 500 multipoles. For the best-fit model, this extra component peaks at l ∼ 450 with an amplitude of 129 μK2, and represents 3.1% of the total power measured by WMAP. Nevertheless, at the 2σ level a null kSZ contribution is still compatible with the data. Part of the detected signal could arise from unmasked point sources and/or Poissonianly distributed foreground residuals. A statistically more significant detection requires the wider frequency coverage and angular resolution of the forthcoming Planck mission.

  6. Poly(acrylic acid) interpolymer complexation: use of a fluorescence time resolved anisotropy as a poly(acrylamide) probe

    OpenAIRE

    Swift, T.; Swanson, L; Rimmer, S.

    2014-01-01

    A low concentration poly(acrylamide) sensor has been developed which uses the segmental mobility of another polymer probe with a covalently attached fluorescent marker. Interpolymer complexation with poly(acrylic acid) leads to reduced segmental mobility which can be used to determine the concentration of polymer in solution. This technique could be useful in detecting the runoff of polymer dispersants and flocculants in fresh water supplies following water purification processes

  7. 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.

  8. FIVE-YEAR WILKINSON MICROWAVE ANISOTROPY PROBE (WMAP) OBSERVATIONS: BAYESIAN ESTIMATION OF COSMIC MICROWAVE BACKGROUND POLARIZATION MAPS

    International Nuclear Information System (INIS)

    We describe a sampling method to estimate the polarized cosmic microwave background (CMB) signal from observed maps of the sky. We use a Metropolis-within-Gibbs algorithm to estimate the polarized CMB map, containing Q and U Stokes parameters at each pixel, and its covariance matrix. These can be used as inputs for cosmological analyses. The polarized sky signal is parameterized as the sum of three components: CMB, synchrotron emission, and thermal dust emission. The polarized Galactic components are modeled with spatially varying power-law spectral indices for the synchrotron, and a fixed power law for the dust, and their component maps are estimated as by-products. We apply the method to simulated low-resolution maps with pixels of side 7.2 deg, using diagonal and full noise realizations drawn from the WMAP noise matrices. The CMB maps are recovered with goodness of fit consistent with errors. Computing the likelihood of the E-mode power in the maps as a function of optical depth to reionization, τ, for fixed temperature anisotropy power, we recover τ = 0.091 ± 0.019 for a simulation with input τ = 0.1, and mean τ = 0.098 averaged over 10 simulations. A 'null' simulation with no polarized CMB signal has maximum likelihood consistent with τ = 0. The method is applied to the five-year WMAP data, using the K, Ka, Q, and V channels. We find τ = 0.090 ± 0.019, compared to τ = 0.086 ± 0.016 from the template-cleaned maps used in the primary WMAP analysis. The synchrotron spectral index, β, averaged over high signal-to-noise pixels with standard deviation σ(β) < 0.25, but excluding ∼6% of the sky masked in the Galactic plane, is -3.03 ± 0.04. This estimate does not vary significantly with Galactic latitude, although includes an informative prior.

  9. Relic gravitational waves in light of the 7-year Wilkinson Microwave Anisotropy Probe data and improved prospects for the Planck mission

    International Nuclear Information System (INIS)

    The new release of data from Wilkinson Microwave Anisotropy Probe improves the observational status of relic gravitational waves. The 7-year results enhance the indications of relic gravitational waves in the existing data and change to the better the prospects of confident detection of relic gravitational waves by the currently operating Planck satellite. We apply to WMAP7 data the same methods of analysis that we used earlier [W. Zhao, D. Baskaran, and L. P. Grishchuk, Phys. Rev. D 80, 083005 (2009)] with WMAP5 data. We also revised by the same methods our previous analysis of WMAP3 data. It follows from the examination of consecutive WMAP data releases that the maximum likelihood value of the quadrupole ratio R, which characterizes the amount of relic gravitational waves, increases up to R=0.264, and the interval separating this value from the point R=0 (the hypothesis of no gravitational waves) increases up to a 2σ level. The primordial spectra of density perturbations and gravitational waves remain blue in the relevant interval of wavelengths, but the spectral indices increase up to ns=1.111 and nt=0.111. Assuming that the maximum likelihood estimates of the perturbation parameters that we found from WMAP7 data are the true values of the parameters, we find that the signal-to-noise ratio S/N for the detection of relic gravitational waves by the Planck experiment increases up to S/N=4.04, even under pessimistic assumptions with regard to residual foreground contamination and instrumental noises. We comment on theoretical frameworks that, in the case of success, will be accepted or decisively rejected by the Planck observations.

  10. Temperature dependence of the perpendicular magnetic anisotropy in Ta/Co2FeAl/MgO structures probed by Anomalous Hall Effect

    Science.gov (United States)

    Gabor, M. S.; Petrisor, T.; Pop, O.; Colis, S.; Tiusan, C.

    2015-10-01

    We report a detailed study of the temperature dependence of the magnetic anisotropy in Ta/Co2FeAl/MgO structures by means of Anomalous Hall Effect measurements. The volume magnetic anisotropy, although negligible at room temperature, shows a non-negligible value at low temperatures and favors an in-plane easy magnetization axis. The surface magnetic anisotropy, which promotes the perpendicular magnetic easy axis, shows an increase from 0.76 ± 0.05 erg /cm2 at 300 K, up to 1.08 ± 0.04 erg /cm2 at 5 K, attributed to the evolution of the Co2FeAl layer saturation magnetization with temperature.

  11. Probing anisotropies of gravitational-wave backgrounds with a space-based interferometer: Geometric properties of antenna patterns and their angular power

    International Nuclear Information System (INIS)

    We discuss the sensitivity to anisotropies of stochastic gravitational-wave backgrounds (GWBs) observed via space-based interferometer. In addition to the unresolved galactic binaries as the most promising GWB source of the planned Laser Interferometer Space Antenna (LISA), the extragalactic sources for GWBs might be detected in the future space missions. The anisotropies of the GWBs thus play a crucial role to discriminate various components of the GWBs. We study general features of antenna pattern sensitivity to the anisotropies of GWBs beyond the low-frequency approximation. We show that the sensitivity of space-based interferometer to GWBs is severely restricted by the data combinations and the symmetries of the detector configuration. The spherical harmonic analysis of the antenna pattern functions reveals that the angular power of the detector response increases with frequency and the detectable multipole moments with effective sensitivity heff∼10-20 Hz-1/2 may reach l∼8-10 at f∼f*=10 mHz in the case of the single LISA detector. However, the cross correlation of optimal interferometric variables is blind to the monopole (l=0) intensity anisotropy, and also to the dipole (l=1) in some case, irrespective of the frequency band. Besides, all the self-correlated signals are shown to be blind to the odd multipole moments (l=odd), independently of the frequency band

  12. Probing anisotropies of gravitational-wave backgrounds with a space-based interferometer: geometric properties of antenna patterns and their angular power

    CERN Document Server

    Kudoh, H; Kudoh, Hideaki; Taruya, Atsushi

    2005-01-01

    We discuss the sensitivity to anisotropies of stochastic gravitational-wave backgrounds (GWBs) observed via space-based interferometer. In addition to the un-resolved Galactic binaries as the most promising GWB source of the planned Laser Interferometer Space Antenna (LISA), the extra-galactic sources for GWBs might be detected in the future space missions. The anisotropies of the GWBs thus play a crucial role to discriminate various components of the GWBs. We study general features of antenna pattern sensitivity to the anisotropies of GWBs beyond the low-frequency approximation. We show that the sensitivity of space-based interferometer to GWBs is severely restricted by the data combinations and the symmetries of the detector configuration. The spherical harmonic analysis of the antenna pattern functions reveals that the angular power of the detector response increases with frequency and the detectable multipole moments with effective sensitivity h_{eff}\\sim 10^{-20} Hz^{-1/2} may reach $\\ell \\sim $ 8 - 10 a...

  13. Secondary anisotropies of the CMB

    International Nuclear Information System (INIS)

    The Cosmic Microwave Background fluctuations provide a powerful probe of the dark ages of the universe through the imprint of the secondary anisotropies associated with the reionization of the universe and the growth of structure. We review the relation between the secondary anisotropies and the primary anisotropies that are directly generated by quantum fluctuations in the very early universe. The physics of secondary fluctuations is described, with emphasis on the ionization history and the evolution of structure. We discuss the different signatures arising from the secondary effects in terms of their induced temperature fluctuations, polarization and statistics. The secondary anisotropies are being actively pursued at present, and we review the future and current observational status

  14. Amiba Observation of CMB Anisotropies

    Science.gov (United States)

    Ng, Kin-Wang

    2003-03-01

    The Array for Microwave Background Anisotropies (AMiBA), a 13-element dual-channel 85-105 GHz interferometer array with full polarization capabilities, is being built to search for high redshift clusters of galaxies via the Sunyaev-Zel'dovich effect as well as to probe the polarization properties of the cosmic microwave background (CMB). We discuss several important issues in the observation of the CMB anisotropies such as observing strategy, l space resolution and mosaicing, optimal estimation of the power spectra, and ground pickup removal.

  15. Probing solute-solvent interaction in 1-ethyl-3-methylimidazolium-based room temperature ionic liquids: A time-resolved fluorescence anisotropy study.

    Science.gov (United States)

    Das, Sudhir Kumar; Sarkar, Moloy

    2014-03-01

    Rotational diffusion of two organic solutes, coumarin153 (C153) and 4-aminophthalimide (AP) has been investigated in four ionic liquids (ILs), viz. 1-ethyl-3-methylimidazolium trifluoroacetate (EMIMTFA), 1-ethyl-3-methylimidazolium ethylsulfate (EMIMESU), 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMTFB) and 1-ethyl-3-methylimidazolium tetracyanoborate (EMIMTCB), as a function of temperature. Between the two probes, AP can act as hydrogen-bond-donor to the solvents having hydrogen bond acceptor ability. The results indicate that the rotational dynamics of C153 is mainly governed by the viscosity of the medium. On the other hand, the rotational motion of AP is found to be significantly hindered in the ILs depending on the nature of anions of the ILs. Rotational coupling constant values for AP in the ILs follow the order TFA > ESU > TCB > TFB. The slower rotational motion of AP in these ILs has been attributed to the specific hydrogen bonding interaction between AP and anions of ILs. PMID:24158315

  16. The anisotropy of granular materials

    OpenAIRE

    Alonso-Marroquin, F.; Luding, S.; Herrmann, H. J.

    2004-01-01

    The effect of the anisotropy on the elastoplastic response of two dimensional packed samples of polygons is investigated here, using molecular dynamics simulation. We show a correlation between fabric coefficients, characterizing the anisotropy of the granular skeleton, and the anisotropy of the elastic response. We also study the anisotropy induced by shearing on the subnetwork of the sliding contacts. This anisotropy provides an explanation to some features of the plastic deformation of gra...

  17. Analysis of complex anisotropy decays from single-frequency polarized-phasor ellipse plots

    Science.gov (United States)

    Kozer, Noga; Clayton, Andrew H. A.

    2016-06-01

    The anisotropy decay of a fluorescently-labelled macromolecule provides information on the internal and global dynamics of the macromolecule. Weber was a pioneer of fluorescent probes, polarization and polarized phase-modulation methods and revealed the power of combining or comparing these methods to disentangle complex modes of emission depolarization. In this paper we take a similar course and show that when measurements of dynamic depolarization are combined with steady-state anisotropy, complex anisotropy decays can be deduced from measurements at a single modulation frequency. Specifically, a double exponential anisotropy decay can be resolved by combining one of the polarized emission phasors with the steady-state anisotropy. The key is the polarized phasor ellipse plot which provides a convenient visualisation aid and reduces the dimensionality of the minimisation problem from three variables to one variable. We illustrate these concepts with an experimental measurement of the anisotropy decay of a small cytoplasmic fluorescent probe in live cells.

  18. Anisotropy in OLEDs

    Science.gov (United States)

    Callens, M. K.; Yokoyama, D.; Neyts, K.

    2015-09-01

    Small-molecule OLEDs, deposited by thermal evaporation, allow for precise control over layer thicknesses. This enables optimisation of the optical behaviour of the stack which ultimately determines the outcoupling efficiency. In terms of optical outcoupling there are limits to the efficiency by which the generated electromagnetic radiation can be extracted from the stack. These limitations are linked to the refractive indices of the individual layers. Values for maximum outcoupling efficiency are sometimes calculated under the implicit assumptions that the OLED stack is planar, that all layers are isotropic with a certain refractive index and that the emitters are not preferentially oriented. In reality it is known that these assumptions are not always valid, be it intentional or unintentional. In our work we transcend these limiting assumptions and look at different forms of anisotropy in OLEDs. Anisotropy in OLEDs comes in three distinct flavours; 1. Geometrical anisotropy, as for example in gratings, lenses or other internal or external scattering centres, 2. Anisotropic emitters, where the orientation significantly influences the direction in which radiation is emitted and 3. Anisotropic optical materials, where their anisotropic nature breaks the customary assumption of isotropic OLED materials. We investigate the effect of these anisotropic features on the outcoupling efficiency and ultimately, on the external quantum efficiency (EQE).

  19. 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...

  20. 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...

  1. 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 of...

  2. 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). The...

  3. A CMB Gibbs sampler for localized secondary anisotropies

    CERN Document Server

    Bull, Philip; Eriksen, Hans Kristian; Ferreira, Pedro G; Fuskeland, Unni; Gorski, Krzysztof M; Jewell, Jeffrey B

    2014-01-01

    As well as primary fluctuations, CMB temperature maps contain a wealth of additional information in the form of secondary anisotropies. Secondary effects that can be identified with individual objects, such as the thermal and kinetic Sunyaev-Zel'dovich (SZ) effects due to galaxy clusters, are difficult to unambiguously disentangle from foreground contamination and the primary CMB, which currently inhibits their use as precision cosmological probes. We develop a Bayesian formalism for rigorously characterising anisotropies that are localised on the sky, taking the TSZ and KSZ effects as an example. Using a Gibbs sampling scheme, we are able to efficiently sample from the joint posterior distribution for a multi-component model of the sky with many thousands of correlated physical parameters. The posterior can then be exactly marginalised to estimate properties of the secondary anisotropies, fully taking into account degeneracies with the other signals in the CMB map. We show that this method is computationally...

  4. Anisotropy in solid inflation

    International Nuclear Information System (INIS)

    In the model of solid / elastic inflation, inflation is driven by a source that has the field theoretical description of a solid. To allow for prolonged slow roll inflation, the solid needs to be extremely insensitive to the spatial expansion. We point out that, because of this property, the solid is also rather inefficient in erasing anisotropic deformations of the geometry. This allows for a prolonged inflationary anisotropic solution, providing the first example with standard gravity and scalar fields only which evades the conditions of the so called cosmic no-hair conjecture. We compute the curvature perturbations on the anisotropic solution, and the corresponding phenomenological bound on the anisotropy. Finally, we discuss the analogy between this model and the f(φ)F2 model, which also allows for anisotropic inflation thanks to a suitable coupling between the inflaton φ and a vector field. We remark that the bispectrum of the curvature perturbations in solid inflation is enhanced in the squeezed limit and presents a nontrivial angular dependence, as had previously been found for the f(φ)F2 model

  5. Anisotropy in rotating drums

    Science.gov (United States)

    Povall, Timothy; McBride, Andrew; Govender, Indresan

    2015-11-01

    An anisotropic relationship between the stress and the strain rate has been observed in two-dimensional simulations of rotating drums. The objective of this work is to investigate the structure of the constitutive relation using three-dimensional discrete-element-method simulations of a rotating drum containing identical rigid spheres for a range of rotational speeds. Anisotropy is quantified from the alignment of the stress and strain rate tensors, with the strain rate computed using a least-squares fit. It is shown that in certain regions there is a strong anisotropic relationship, regardless of the speed of rotation. The effective friction coefficient is examined in order to determine the phase space in which the μ (I) rheology is valid. Lastly, a depth-averaged approach through the flowing layer is employed to determine the relationship between the velocity tangential to the equilibrium surface and the height of the flowing layer. A power-law relationship that approaches linear at high speeds is observed. Supported by NRF/DST Scarce Skills (South Africa).

  6. Neutrino Anisotropies after Planck

    CERN Document Server

    Gerbino, Martina; Said, Najla

    2013-01-01

    We present new constraints on the rest-frame sound speed, c_eff^2, and the viscosity parameter, c_vis^2, of the Cosmic Neutrino Background from the recent measurements of the Cosmic Microwave Background anisotropies provided by the Planck satellite. While broadly consistent with the ex- pectations of c_eff^2 = c_vis^2 = 1/3 in the standard scenario, the Planck dataset hints for a higher value of the viscosity parameter, with c_vis^2 = 0.60 +/- 0.18 at 68% c.l., and a lower value of the sound speed, with c_eff^2 = 0.304 +/- 0.013 at 68% c.l.. We find a correlation between the neutrino parameters and the lensing amplitude of the temperature power spectrum A_L. When the latter parameter is allowed to vary, we find a better consistency with the standard model with c_vis^2 = 0.51 +/- 0.22, c_eff^2 = 0.311 +/- 0.019 and A_L = 1.08 +/- 0.18 at 68% c.l.. This result indicates that the anomalous large value of A_L measured by Planck could be connected to non-standard neutrino properties. Including additional datasets ...

  7. Flow stress anisotropy in aluminium

    DEFF Research Database (Denmark)

    Juul Jensen, D.; Hansen, N.

    1990-01-01

    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 < 3.00). Flow stresses (0.2% offset) were measured at room temperature by uniaxial...... 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 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 is...

  8. Braneworld cosmological models with anisotropy

    International Nuclear Information System (INIS)

    For a cosmological Randall-Sundrum braneworld with anisotropy, i.e., of Bianchi type, the modified Einstein equations on the brane include components of the five-dimensional Weyl tensor for which there are no evolution equations on the brane. If the bulk field equations are not solved, this Weyl term remains unknown, and many previous studies have simply prescribed it as ad hoc. We construct a family of Bianchi braneworlds with anisotropy by solving the five-dimensional field equations in the bulk. We analyze the cosmological dynamics on the brane, including the Weyl term, and shed light on the relation between anisotropy on the brane and the Weyl curvature in the bulk. In these models, it is not possible to achieve geometric anisotropy for a perfect fluid or scalar field - the junction conditions require anisotropic stress on the brane. But the solutions can isotropize and approach a Friedmann brane in an anti-de Sitter bulk

  9. Braneworld cosmological models with anisotropy

    Science.gov (United States)

    Campos, Antonio; Maartens, Roy; Matravers, David; Sopuerta, Carlos F.

    2003-11-01

    For a cosmological Randall-Sundrum braneworld with anisotropy, i.e., of Bianchi type, the modified Einstein equations on the brane include components of the five-dimensional Weyl tensor for which there are no evolution equations on the brane. If the bulk field equations are not solved, this Weyl term remains unknown, and many previous studies have simply prescribed it as ad hoc. We construct a family of Bianchi braneworlds with anisotropy by solving the five-dimensional field equations in the bulk. We analyze the cosmological dynamics on the brane, including the Weyl term, and shed light on the relation between anisotropy on the brane and the Weyl curvature in the bulk. In these models, it is not possible to achieve geometric anisotropy for a perfect fluid or scalar field—the junction conditions require anisotropic stress on the brane. But the solutions can isotropize and approach a Friedmann brane in an anti de Sitter bulk.

  10. Braneworld cosmological models with anisotropy

    CERN Document Server

    Campos, A; Matravers, D; Sopuerta, C F; Campos, Antonio; Maartens, Roy; Matravers, David; Sopuerta, Carlos F.

    2003-01-01

    For a cosmological Randall-Sundrum braneworld with anisotropy, i.e., of Bianchi type, the modified Einstein equations on the brane include components of the five-dimensional Weyl tensor for which there are no evolution equations on the brane. If the bulk field equations are not solved, this Weyl term remains unknown, and many previous studies have simply prescribed it ad hoc. We construct a family of Bianchi braneworlds with anisotropy by solving the five-dimensional field equations in the bulk. We analyze the cosmological dynamics on the brane, including the Weyl term, and shed light on the relation between anisotropy on the brane and Weyl curvature in the bulk. In these models, it is not possible to achieve geometric anisotropy for a perfect fluid or scalar field -- the junction conditions require anisotropic stress on the brane. But the solutions can isotropize and approach a Friedmann brane in an anti-de Sitter bulk.

  11. Broadband optical limiter based on nonlinear photoinduced anisotropy in bacteriorhodopsin film

    Science.gov (United States)

    Huang, Yuhua; Siganakis, Georgios; Moharam, M. G.; Wu, Shin-Tson

    2004-11-01

    Nonlinear photoinduced anisotropy in a bacteriorhodopsin film was theoretically and experimentally investigated and a broadband active optical limiter was demonstrated in the visible spectral range. A diode-pumped second harmonic yttrium aluminum garnet laser was used as a pumping beam and three different wavelengths at λ =442, 532, and 655nm from different lasers were used as probing beams. The pump and probe beams overlap at the sample. When the pumping beam is absent, the probing beam cannot transmit the crossed polarizers. With the presence of the pumping beam, a portion of the probing light is detected owing to the photoinduced anisotropy. Due to the optical nonlinearity, the transmitted probing beam intensity is clamped at a certain value, which depends on the wavelength, when the pumping beam intensity exceeds 5mW/mm2. Good agreement between theory and experiment is found.

  12. Probing vibrational anisotropy with nuclear resonance vibrational spectroscopy.

    Energy Technology Data Exchange (ETDEWEB)

    Pavlik, J. W.; Barabanschikov, A.; Oliver, A. G.; Alp, E. E.; Sturhahn, W.; Zhao, J.; Sage, J. T.; Scheidt, W. R. (X-Ray Science Division); (Univ. of Notre Dame); (Northeastern Univ.)

    2010-06-14

    A NRVS single-crystal study (NRVS=nuclear resonance vibrational spectroscopy) has provided detailed information on the in-plane modes of nitrosyl iron porphyrinate [Fe(oep)(NO)] (see picture; oep=octaethylporphyrin). The axial nitrosyl ligand controls the direction of the in-plane iron motion.

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

    Indian Academy of Sciences (India)

    Robert G Crittenden

    2004-10-01

    It has been a little over a year since WMAP produced its dramatic new glimpse of the cosmic microwave background. I review the results of the WMAP mission and the science that has arisen from it, focusing on the qualitatively new features of the data: the temperature-polarization correlation, correlations with large scale structure, the large-scale power deficit and its implications, and the search for non-Gaussianity.

  14. Spin confinement by anisotropy modulation

    Energy Technology Data Exchange (ETDEWEB)

    Bland, J.A.C. [Cavendish Laboratory, University of Cambridge, Cambridge (United Kingdom)]. E-mail: jacb1@phy.cam.ac.uk; Lew, W.S.; Li, S.P.; Lopez-Diaz, L.; Vaz, C.A.F. [Cavendish Laboratory, University of Cambridge, Cambridge (United Kingdom); Natali, M.; Chen, Y. [Laboratoire de Photonique et de Nanostructures, CNRS-LPN, Marcoussis (France)

    2002-10-07

    The spin configuration in a magnet is in general a 'natural' consequence of both the intrinsic properties of the material and the sample dimensions. We demonstrate that this limitation can be overcome in a homogeneous ferromagnetic film by engineering an anisotropy contrast. Substrates with laterally modulated single-crystal and polycrystalline surface regions were used to induce selective epitaxial growth of a ferromagnetic Ni film. The resulting spatially varying magnetic anisotropy leads to regular perpendicular and in-plane magnetic domains, separated by a new type of magnetic domain wall-the 'anisotropy constrained' magnetic wall. Micromagnetic simulations indicate that the wall is asymmetric, has a small out-of-plane component and has no mobility under external perturbation. (author)

  15. Spin confinement by anisotropy modulation

    Science.gov (United States)

    Bland, J. A. C.; Lew, W. S.; Li, S. P.; Lopez-Diaz, L.; Vaz, C. A. F.; Natali, M.; Chen, Y.

    2002-10-01

    The spin configuration in a magnet is in general a `natural' consequence of both the intrinsic properties of the material and the sample dimensions. We demonstrate that this limitation can be overcome in a homogeneous ferromagnetic film by engineering an anisotropy contrast. Substrates with laterally modulated single-crystal and polycrystalline surface regions were used to induce selective epitaxial growth of a ferromagnetic Ni film. The resulting spatially varying magnetic anisotropy leads to regular perpendicular and in-plane magnetic domains, separated by a new type of magnetic domain wall-the `anisotropy constrained' magnetic wall. Micromagnetic simulations indicate that the wall is asymmetric, has a small out-of-plane component and has no mobility under external perturbation.

  16. Spacetime anisotropy affects cosmological entanglement

    CERN Document Server

    Pierini, Roberto; Mancini, Stefano

    2016-01-01

    Most existing cosmological entanglement studies are focused on the isotropic Robertson-Walker (RW) spacetime. Here we go beyond this limitation and study the influence of anisotropy on entanglement generated by dynamical spacetime. Since the isotropic spacetime is viewed as a background medium and the anisotropy is incorporated as perturbation, we decompose entanglement entropy into isotropic and anisotropic contributions. The latter is shown to be non-negligible by analyzing two cosmological models with weak and conformal coupling. We also show the possibility of using entanglement to infer about universe features.

  17. 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...

  18. CMB Anisotropies by Collapsing Textures

    OpenAIRE

    Sousa, Kepa; Urrestilla, Jon

    2013-01-01

    CMB photons passing through a collapsing texture knot receive an energy shift, creating characteristic cold and hot spots on the sky. We calculate the anisotropy pattern produced by collapsing texture knots of arbitrary shape. The texture dynamics are solved numerically on a Minkowski background.

  19. Ultrasonic characterization of CFRP anisotropy

    Czech Academy of Sciences Publication Activity Database

    Kling, M.; Tokar, Daniel; Převorovský, Zdeněk

    Praha: ČVUT v Praze, 2015 - (Hobza, T.), s. 71-80 ISBN 978-80-01-05841-1. [Stochastic and Physical Monitoring Systems 2015. Praha (CZ), 22.06.2015-27.06.2015] Institutional support: RVO:61388998 Keywords : anisotropy * carbon fiber -reinforced plastic * ultrasonic testing * signal processing Subject RIV: BI - Acoustics

  20. 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.

  1. Excitonic intraband relaxation and polarization anisotropies in PTCDA on femtosecond and picosecond timescales

    International Nuclear Information System (INIS)

    We report on investigations of optical excitations in polycrystalline organic molecular crystals with quasi-1D-stacked crystal structure and negative exciton dispersion. As model system, we choose thin films of the perylene derivative 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA). Using pump-probe spectroscopy, we show how the relaxation from the absorbing state towards the border of the Brillouin zone occurs on a 120 fs timescale. Time-resolved luminescence anisotropy gives evidence that as a result of the coherent coupling between adjacent stacks, populations of the Davydov-split states that are prepared during photo-excitation relax into the emitting states in less than 5 ps. The behavior of the luminescence anisotropy can be explained by the orientation of the two PTCDA molecules in the unit cell. However, a full understanding of the ultrafast pump-probe anisotropy requires novel explanations beyond current models

  2. Cosmic ray anisotropy and its time variations

    International Nuclear Information System (INIS)

    Cosmic ray anisotropy is analysed on the base of the data of the worldwide network of neutron monitors for the period of 1958-1972. 11-year variation of anisotropy phase and amplitude is investigated. Three-dimensional cosmic ray anisotropy in interplanetary space is calculated. (orig./WBU)

  3. 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. Thi

  4. On the origin of the cosmic microwave background anisotropies

    OpenAIRE

    Follop, Ria; Rassat, Anais; Cooray, Asantha; Abdalla, Filipe B.

    2007-01-01

    Suggestions have been made that the microwave background observed by COBE and WMAP and dubbed Cosmic Microwave Background (CMB) may have an origin within our own Galaxy or Earth. To consider the signal that may be correlated with Earth, a correlate-by-eye exercise was attempted by overlaying the CMB map from Wilkinson Microwave Anisotropy Probe on a topographical map of Earth. Remarkably, several hot spots in the CMB map are found to be well aligned with either large cities on Earth or region...

  5. Magnetoresistance Anisotropy in WTe2

    Science.gov (United States)

    Thoutam, Laxman Raju; Wang, Yonglei; Xiao, Zhili; Das, Saptarshi; Luican Mayer, Adina; Divan, Ralu; Crabtree, George W.; Kwok, Wai Kwong

    We report the angle dependence of the magnetoresistance in WTe2. Being a layered material, WTe2 is considered to be electronically two-dimensional (2D). Our results demonstrate that it is in fact 3D with an anisotropy of effective mass as small as 2. We measured the magnetic field dependence of the sample resistance R(H) at various angles between the applied magnetic field with respect to the c-axis of the crystal and found that they can be scaled based on the mass anisotropy, which changes from ~2 to ~5 with decreasing temperature in the Fermi liquid state. We will also discuss the origin of the turn-on temperature behavior in this material.

  6. Microwave Anisotropies from Random Sources

    CERN Document Server

    Ferreira, P G

    1996-01-01

    I report on recent developments in the theory of cosmic background radiation perturbations. I describe ways of modeling alternatives to the canonical Gaussian theories within the standard framework of cosmological perturbation theory. Some comments are made on using these techniques to resolve the uncertainties in theories of structure formation with topological defects. (To appear in the proceedings of the XXXIth Moriond meeting, ``Microwave Background Anisotropies'')

  7. [Cosmic Microwave Background (CMB) Anisotropies

    Science.gov (United States)

    Silk, Joseph

    1998-01-01

    One of the main areas of research is the theory of cosmic microwave background (CMB) anisotropies and analysis of CMB data. Using the four year COBE data we were able to improve existing constraints on global shear and vorticity. We found that, in the flat case (which allows for greatest anisotropy), (omega/H)0 less than 10-7, where omega is the vorticity and H is the Hubble constant. This is two orders of magnitude lower than the tightest, previous constraint. We have defined a new set of statistics which quantify the amount of non-Gaussianity in small field cosmic microwave background maps. By looking at the distribution of power around rings in Fourier space, and at the correlations between adjacent rings, one can identify non-Gaussian features which are masked by large scale Gaussian fluctuations. This may be particularly useful for identifying unresolved localized sources and line-like discontinuities. Levin and collaborators devised a method to determine the global geometry of the universe through observations of patterns in the hot and cold spots of the CMB. We have derived properties of the peaks (maxima) of the CMB anisotropies expected in flat and open CDM models. We represent results for angular resolutions ranging from 5 arcmin to 20 arcmin (antenna FWHM), scales that are relevant for the MAP and COBRA/SAMBA space missions and the ground-based interferometer. Results related to galaxy formation and evolution are also discussed.

  8. [Cosmic Microwave Background (CMB) Anisotropies

    Science.gov (United States)

    Silk, Joseph

    1998-01-01

    One of the main areas of research is the theory of cosmic microwave background (CMB) anisotropies and analysis of CMB data. Using the four year COBE data we were able to improve existing constraints on global shear and vorticity. We found that, in the flat case (which allows for greatest anisotropy), (omega/H)0 less than 10(exp -7), where omega is the vorticity and H is the Hubble constant. This is two orders of magnitude lower than the tightest, previous constraint. We have defined a new set of statistics which quantify the amount of non-Gaussianity in small field cosmic microwave background maps. By looking at the distribution of power around rings in Fourier space, and at the correlations between adjacent rings, one can identify non-Gaussian features which are masked by large scale Gaussian fluctuations. This may be particularly useful for identifying unresolved localized sources and line-like discontinuities. Levin and collaborators devised a method to determine the global geometry of the universe through observations of patterns in the hot and cold spots of the CMB. We have derived properties of the peaks (maxima) of the CMB anisotropies expected in flat and open CDM models. We represent results for angular resolutions ranging from 5 arcmin to 20 arcmin (antenna FWHM), scales that are relevant for the MAP and COBRA/SAMBA space missions and the ground-based interferometer. Results related to galaxy formation and evolution are also discussed.

  9. Probing magnetochirality

    Indian Academy of Sciences (India)

    Rupamanjari Ghosh

    2002-08-01

    Magnetochiral anisotropy refers to the phenomenon that when light is passed through a chiral medium placed in an external magnetic field, the refractive index, or equivalently, the absorption encountered by the light differs depending on whether it travels parallel or antiparallel to the magnetic field. It is a very small effect, the change in refractive index because of this effect alone being of the order of 10-11. This effect has recently been measured in an active ring laser interferometer in which the detection scheme convincingly eliminates the contributions from natural optical activity, the Faraday effect and other stray anisotropies in the system. The phenomenon is important in the context of fundamental interactions between light and matter and the governing symmetry principles, and also in biochemistry as one possible explanation for the homochirality of life.

  10. On the problem of electron-induced anisotropy effect in As2S3-based glasses

    International Nuclear Information System (INIS)

    Effect of electron-induced anisotropy was observed in glassy As2S3-based samples irradiated by accelerated electrons (E=2.8 MeV) in the perpendicular plane to the probe light. Spectral and compositional dependences of this effect and its time stability at room temperature were discussed. It was supposed that the microstructural mechanism of the anisotropy effect was connected with electron-induced formation of new oriented (relatively to the electron flow) defects in the form of broken chemical bonds

  11. Lichtinduzierte Generierung und Charakterisierung optischer Anisotropie

    OpenAIRE

    Jung, Carl Christoph

    2005-01-01

    Eine Nutzung der optischen Anisotropie dünner Schichten ist vor allem für die Displaytechnologie, die optische Datenspeicherung und für optische Sicherheitselemente von hoher Bedeutung. Diese Doktorarbeit befasst sich mit theoretischen und experimentellen Untersuchung von dreidimensionaler Anisotropie und dabei insbesondere mit der Untersuchung von lichtinduzierter dreidimensionaler Anisotropie in organischen dünnen Polymer-Schichten. Die gewonnenen Erkentnisse und entwickelten Methoden könne...

  12. Anomalous Nernst Effect with Magnetocrystalline Anisotropy (110)

    Science.gov (United States)

    Chesman, Carlos; Costa Neto, Jose; Department of Physics-UFRN Team

    2014-03-01

    When a ferromagnetic material is submitted to a temperature gradient and the magnetic field generates voltage on the edges of the samples, this is called the Anomalous Nernst Effect (ANE). The Heusler alloys that currently exhibit this effect are the most promising for spintronics and spin caloritronics. In this study we perform a theoretical investigation of voltage curves associated to the ANE, when the material displays magnetocrystalline anisotropy for experimental results in two configurations, ANE versus applied magnetic field and planar angle variations of ANE. We analyzed three types of magnetocrystalline anisotropy: cubic anisotropy (100) with C4 symmetry, uniaxial anisotropy with C2 symmetry and cubic anisotropy (110). The aim was to prove that cubic anisotropy (110) is equivalent to anisotropy (100) combined with uniaxial anisotropy. Theoretical fitting of experimental ANE data demonstrates this total equivalence and that a new interpretation with the use of cubic anisotropy (110) may be due to the atomic arrangement of the so-called full-Heusler. Comparative analyses of Co2FeAl and Co2MnGe alloys will be presented. CNPq, CAPES, FAPERN.

  13. DNA probes

    International Nuclear Information System (INIS)

    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 32P. 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

  14. Probing Capacity

    CERN Document Server

    Asnani, Himanshu; Weissman, Tsachy

    2010-01-01

    We consider the problem of optimal probing of states of a channel by transmitter and receiver for maximizing rate of reliable communication. The channel is discrete memoryless (DMC) with i.i.d. states. The encoder takes probing actions dependent on the message. It then uses the state information obtained from probing causally or non-causally to generate channel input symbols. The decoder may also take channel probing actions as a function of the observed channel output and use the channel state information thus acquired, along with the channel output, to estimate the message. We refer to the maximum achievable rate for reliable communication for such systems as the 'Probing Capacity'. We characterize this capacity when the encoder and decoder actions are cost constrained. To motivate the problem, we begin by characterizing the trade-off between the capacity and fraction of channel states the encoder is allowed to observe, while the decoder is aware of channel states. In this setting of 'to observe or not to o...

  15. Measuring nanoscale forces with living probes.

    Science.gov (United States)

    Olof, S N; Grieve, J A; Phillips, D B; Rosenkranz, H; Yallop, M L; Miles, M J; Patil, A J; Mann, S; Carberry, D M

    2012-11-14

    Optical trapping techniques have been used to investigate fundamental biological processes ranging from the identification of the processive mechanisms of kinesin and myosin to understanding the mechanics of DNA. To date, these investigations have relied almost exclusively on the use of isotropic probes based on colloidal microspheres. However, there are many potential advantages in utilizing more complex probe morphologies: use of multiple trapping points enables control of the interaction volume; increasing the distance between the optical trap and the sample minimizes photodamage in sensitive biological materials; and geometric anisotropy introduces the potential for asymmetric surface chemistry and multifunctional probes. Here we demonstrate that living cells of the freshwater diatom Nitzschia subacicularis Hustedt can be exploited as advanced probes for holographic optical tweezing applications. We characterize the optical and material properties associated with the high shape anisotropy of the silica frustule, examine the trapping behavior of the living algal cells, and demonstrate how the diatoms can be calibrated for use as force sensors and as force probes in the presence of rat B-cell hybridoma (11B11) cells. PMID:23092335

  16. Crystal growth and anisotropy of high temperature thermoelectric properties of yttrium borosilicide single crystals

    Science.gov (United States)

    Hossain, M. Anwar; Tanaka, Isao; Tanaka, Takaho; Khan, A. Ullah; Mori, Takao

    2016-01-01

    We studied thermoelectric properties of YB41Si1.3 single crystals grown by the floating zone method. The composition of the grown crystal was confirmed by electron probe micro-analysis. We have determined the growth direction for the first time for these borosilicides, and discovered relatively large anisotropy in electrical properties. We measured the electrical resistivity and Seebeck coefficient along [510] (the growth direction) and [052] directions and we found that this crystal exhibits strong electrical anisotropy with a maximum of more than 8 times. An interesting layered structural feature is revealed along [510] with dense boron cluster layers and yttrium layers, with conductivity enhanced along this direction. We obtained 3.6 times higher power factor along [510] compared to that along [052]. Although the ZT of the present system is low, anisotropy in the thermoelectric properties of a boride was reported for the first time, and can be a clue in developing other boride systems also.

  17. Anisotropy of successive air showers

    Science.gov (United States)

    Ochi, N.; Wada, T.; Yamashita, Y.; Ohashi, A.; Yamamoto, I.; Nakatsuka, T.; Large Area Air Shower (LAAS) Group

    2001-04-01

    We have investigated the anisotropy of successive air shower (SAS) events, which we define as the detection of many air showers within a short time window, using data from six stations of the Large Area Air Shower (LAAS) group. On the criterion of 22 air showers within 20 minutes, five SAS events are found against 1.4 expected from the Poisson distribution in Okayama University station's data. From six stations' data, we find 24 SAS events in total. By plotting them in equatorial coordinates, it is revealed that SAS events are observed more frequently when the Galactic plane is around the zenith. This can be attributed to a hypothetical small flux of ultra-high-energy γ-rays from the direction of the Galactic plane superposed on conventional cosmic rays. If this hypothesis is true, the analytical procedure used here has potential to measure ultra-high-energy γ-ray sources by even small air shower arrays like ours.

  18. Anisotropy of successive air showers

    International Nuclear Information System (INIS)

    We have investigated the anisotropy of successive air shower (SAS) events, which we define as the detection of many air showers within a short time window, using data from six stations of the Large Area Air Shower (LAAS) group. On the criterion of 22 air showers within 20 minutes, five SAS events are found against 1.4 expected from the Poisson distribution in Okayama University station's data. From six stations' data, we find 24 SAS events in total. By plotting them in equatorial coordinates, it is revealed that SAS events are observed more frequently when the Galactic plane is around the zenith. This can be attributed to a hypothetical small flux of ultra-high-energy γ-rays from the direction of the Galactic plane superposed on conventional cosmic rays. If this hypothesis is true, the analytical procedure used here has potential to measure ultra-high-energy γ-ray sources by even small air shower arrays like ours

  19. CMB anisotropy science: a review

    CERN Document Server

    Challinor, Anthony

    2012-01-01

    The cosmic microwave background (CMB) provides us with our most direct observational window to the early universe. Observations of the temperature and polarization anisotropies in the CMB have played a critical role in defining the now-standard cosmological model. In this contribution we review some of the basics of CMB science, highlighting the role of observations made with ground-based and balloon-borne Antarctic telescopes. Most of the ingredients of the standard cosmological model are poorly understood in terms of fundamental physics. We discuss how current and future CMB observations can address some of these issues, focusing on two directly relevant for Antarctic programmes: searching for gravitational waves from inflation via B-mode polarization, and mapping dark matter through CMB lensing.

  20. Statistical anisotropy from inflationary magnetogenesis

    CERN Document Server

    Giovannini, Massimo

    2016-01-01

    Provided the quantum fluctuations are amplified in the presence of a classical gauge field configuration the resulting curvature perturbations exhibit a mild statistical anisotropy which should be sufficiently weak not to conflict with current observational data. The curvature power spectra induced by weakly anisotropic initial states are computed here for the first time when the electric and the magnetic gauge couplings evolve at different rates as it happens, for instance, in the relativistic theory of van der Waals interactions. After recovering the results valid for coincident gauge couplings, the constraints imposed by the isotropy and the homogeneity of the initial states are discussed. The obtained bounds turn out to be more stringent than naively expected and cannot be ignored when discussing the underlying magnetogenesis scenarios.

  1. Polarization-modulation setup for ultrafast infrared anisotropy experiments to study liquid dynamics.

    Science.gov (United States)

    Tros, Martijn; Woutersen, Sander

    2015-06-01

    An infrared pump-probe setup using rapid polarization modulation has been developed to perform time-resolved vibrational anisotropy measurements. A photo-elastic modulator is used as a rapidly switchable half-wave plate, enabling the measurement of transient absorptions for parallel and perpendicular polarizations of the pump and probe pulses on a shot-to-shot basis. In this way, infrared intensity fluctuations are nearly completely canceled, significantly enhancing the accuracy of the transient-anisotropy measurement. The method is tested on the OD-stretch vibration of HDO in H2O, for which the signal-to-noise ratio is found to be 4 times better than with conventional methods. PMID:26030569

  2. High Redshift Intergalactic Medium: Probes and Physical Models

    CERN Document Server

    Sethi, S K

    2004-01-01

    Recent years have seen major advances in understanding the state of the intergalactic medium (IGM) at high redshift. Some aspects of this understanding are reviewed here. In particular, we discuss: (1) Different probes of IGM like Gunn-Peterson test, CMBR anisotropies, and neutral hydrogen emission from reionization, and (2) some models of reionization of the universe.

  3. Primordial anisotropies in gauged hybrid inflation

    International Nuclear Information System (INIS)

    We study primordial anisotropies generated in the model of gauged hybrid inflation in which the complex waterfall field is charged under a U(1)gauge field. Primordial anisotropies are generated either actively during inflation or from inhomogeneities modulating the surface of end of inflation during waterfall transition. We present a consistent δN mechanism to calculate the anisotropic power spectrum and bispectrum. We show that the primordial anisotropies generated at the surface of end of inflation do not depend on the number of e-folds and therefore do not produce dangerously large anisotropies associated with the IR modes. Furthermore, one can find the parameter space that the anisotropies generated from the surface of end of inflation cancel the anisotropies generated during inflation, therefore relaxing the constrains on model parameters imposed from IR anisotropies. We also show that the gauge field fluctuations induce a red-tilted power spectrum so the averaged power spectrum from the gauge field can change the total power spectrum from blue to red. Therefore, hybrid inflation, once gauged under a U(1) field, can be consistent with the cosmological observations

  4. Anisotropy of rare-earth magnets

    Institute of Scientific and Technical Information of China (English)

    R.Skomski; D.J.Sellmyer

    2009-01-01

    Rare-earth intermetallics such as Nd2FeI4B and Sm-Co are widely used as high-performance permanent magnets,because they combine high magnetocrystalline anisotropy with reasonable magnetization and Curie temperature.The anisotropy is a combined effect of spin-orbit coupling and electrostatic crystal-field interactions.The main contribution comes from the rare-earth 4f electrons,which are well-screened from the crystalline environment but exhibit a strong spin-orbit coupling.In this limit,the magnetocrystalline anisotropy has a very transparent physical interpretation,the anisotropy energy essentially being equal to the energy of Hund's-rules 4f ion in the crystal field.The corresponding expression for the lowest-order uniaxial anisotropy constant K1 is used to discuss rare-earth substitutions,which have recently attracted renewed interest due to shifts in the rare-earth production and demand.Specific phenomena reviewed in this article are the enhancement of the anisotropy of Sm2Fe17 due to interstitial nitrogen,the use of Sm-Co magnets for high-temperature applications,and the comparison of rare-earth single-ion anisotropy with other single-ion and two-ion mechanisms.

  5. Preparation and Fluorescence Anisotropy Study of a Ribonuclease-Lucifer Yellow Conjugate

    Science.gov (United States)

    Malone, C. C.; Sumida, J.; Pusey, M. L.; Rose, M. Franklin (Technical Monitor)

    2000-01-01

    We have prepared a chemical derivative of ribonuclease A (RNase) with lucifer yellow (LY). The rotational dynamics of the LY-RNase conjugate were characterized by steady state and time resolved fluorescence techniques. Steady state anisotropy measurements were performed at varying viscosities at 10C and 20C, and the rotational correlation time of both RNase and the covalently linked LY probe were determined by time resolved frequency domain measurements. Our data suggest that the fluorophore is rigidly bound at 10C.

  6. Influence of interface exchange coupling in perpendicular anisotropy [Pt/Co]50/TbFe bilayers

    OpenAIRE

    Mangin, S.; Hauet, Thomas; Fischer, P.; Kim, D. H.; Kortright, J.B.; Chesnel, K.; Arenholz, E.; Fullerton, Eric E.

    2008-01-01

    International audience We present the magnetization evolution of perpendicular anisotropy TbFe and ͓Co/ Pt͔ 50 thin films either in direct contact resulting in antiferromagnetic interfacial coupling or separated by a thick decoupling Pt layer. Magnetometry and x-ray magnetic circular dichroism spectroscopy determine the spatially averaged magnetic properties. Resonant magnetic x-ray small-angle scattering and magnetic soft x-ray transmission microscopy probed the domain configurations and ...

  7. Report on 3- and 4-Point Correlation Statistics in COBE DMR Anisotropy Maps

    Science.gov (United States)

    Hinshaw, Gary; Gorski, Krzystof M.; Bennett, Charles L.; Banday, Anthony J.

    1996-01-01

    As part of the work performed under this contract, we have computed the 3- and 4-point correlation functions of the COBE-DMR 2-year and 4-year anisotropy maps. The results of our work showed that the 3-point correlation function is consistent with zero and that the 4-point function is not a very sensitive probe of non-Gaussian behavior in the COBE-DMR data.

  8. A subnanomolar fluorescent probe for protein kinase CK2 interaction studies

    DEFF Research Database (Denmark)

    Enkvist, Erki; Viht, Kaido; Bischoff, Nils;

    2012-01-01

    -1502 with PromoFluor-647 gave the fluorescent probe ARC-1504 that possessed subnanomolar affinity towards both CK2α and the holoenzyme. The probe was used in a fluorescence anisotropy-based binding assay to measure the concentration of CK2α and characterize non-labelled ligands binding to the active...

  9. CMB Anisotropies: Their Discovery and Utilization

    CERN Document Server

    Smoot, George F

    2008-01-01

    This article is a written and modified version of a talk presented at the conference `A Century of Cosmology' held at San Servolo, Venice, Italy, in August 2007. The talk focuses on some of the cosmology history leading to the discovery and exploitation of Cosmic Microwave Background (CMB) Radiation anisotropies. We have made tremendous advances first in the development of the techniques to observe these anisotropies and in observing and interpreting them to extract their contained cosmological information. CMB anisotropies are now a cornerstone in our understanding of the cosmos and our future progress in the field. This is an outcome that Dennis Sciama hoped for and encouraged.

  10. Magnetic Domain Confinement by Anisotropy Modulation

    Science.gov (United States)

    Li, S. P.; Lew, W. S.; Bland, J. A.; Lopez-Diaz, L.; Vaz, C. A.; Natali, M.; Chen, Y.

    2002-02-01

    The spin configuration in a magnet is in general a ``natural'' consequence of both the intrinsic properties of the material and the sample dimensions. We demonstrate that this limitation can be overcome in a homogeneous ferromagnetic film by engineering an anisotropy contrast. Substrates with laterally modulated single-crystal and polycrystalline surface regions were used to induce selective epitaxial growth of a ferromagnetic Ni film. The resulting spatially varying magnetic anisotropy leads to regular perpendicular and in-plane magnetic domains, separated by a new type of magnetic wall-the ``anisotropy constrained'' magnetic wall.

  11. Apparent resistivity of azimuthal anisotropy layered media

    Institute of Scientific and Technical Information of China (English)

    阮爱国; 毛桐恩; 李清河; 葛双成

    2002-01-01

    The electric field, equations of boundary conditions and calculation formula of apparent resistivity are derived for azimuthal anisotropy layered media with DC method based on anisotropic Ohm(s law. Taking Schlumberger symmetric system as an example and using recurrence formula of nuclear function, the paper theoretically simulates a model of four layers with the same anisotropy coefficient for each layer. The deep sounding curves of resistivity and the pattern of contours are obtained for the model. The results shows the theoretical formula of this paper is correct, the deep sounding curves not only exhibit the difference of resistivity among layers but also indicate the anisotropy characteristics of layers.

  12. Exhaustive study of cosmic microwave background anisotropies in quintessential scenarios

    Science.gov (United States)

    Brax, Philippe; Martin, Jérôme; Riazuelo, Alain

    2000-11-01

    Recent high-precision measurements of the CMB anisotropies performed by the BOOMERanG and MAXIMA-1 experiments provide an unmatched set of data allowing us to probe different cosmological models. Among these scenarios, motivated by the recent measurements of the luminosity distance versus redshift relation for type Ia supernovas, is the quintessence hypothesis. It consists of 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 presence of quintessence. We also compare the CMB multipoles calculated with the help of a full Boltzmann code with the BOOMERanG and MAXIMA-1 data. We pay special attention to the location of the second peak and demonstrate that it significantly differs from the location obtained in the cosmological constant case. Finally, we argue that the SUGRA potential is compatible with all the recent data with standard values of the cosmological parameters. In particular, it fits the MAXIMA-1 data better than a cosmological constant or the Ratra-Peebles potential.

  13. Fracture toughness anisotropy in shale

    Science.gov (United States)

    Chandler, Michael R.; Meredith, Philip G.; Brantut, Nicolas; Crawford, Brian R.

    2016-03-01

    The use of hydraulic fracturing to recover shale gas has focused attention on the fundamental fracture properties of gas-bearing shales, but there remains a paucity of available experimental data on their mechanical and physical properties. Such shales are strongly anisotropic, so that their fracture propagation trajectories depend on the interaction between their anisotropic mechanical properties and the anisotropic in situ stress field in the shallow crust. Here we report fracture toughness measurements on Mancos shale determined in all three principal fracture orientations: Divider, Short Transverse, and Arrester, using a modified short-rod methodology. Experimental results for a range of other sedimentary and carbonate rocks are also reported for comparison purposes. Significant anisotropy is observed in shale fracture toughness measurements at ambient conditions, with values, as high as 0.72 MPa m1/2 where the crack plane is normal to the bedding, and values as low as 0.21 MPa m1/2 where the crack plane is parallel to the bedding. For cracks propagating nonparallel to bedding, we observe a tendency for deviation toward the bedding-parallel orientation. Applying a maximum energy release rate criterion, we determined the conditions under which such deviations are more or less likely to occur under more generalized mixed-mode loading conditions. We find for Mancos shale that the fracture should deviate toward the plane with lowest toughness regardless of the loading conditions.

  14. Higher order anisotropies in the Buda-Lund model -- disentangling flow and density field anisotropies

    CERN Document Server

    Lökös, Sándor; Csörgő, Tamás; Tomášik, Boris

    2016-01-01

    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.

  15. Shell effects and fission fragments angular anisotropy

    International Nuclear Information System (INIS)

    The impact of the shell corrections attenuation effect with growth of the fissionable nuclei temperature on the angular anisotropy of the fission fragments is considered. The experimental data on the anisotropy of the fission fragments angular distributions of the compound nucleus, formed in the 4He + 238U reactions, are analyzed within the frames of the transition states model in the fission barriers saddle point and statistic theory of nuclear reactions. The obvious kind of the shell corrections attenuation function is obtained

  16. Conductivity-type anisotropy in molecular solids

    OpenAIRE

    Ostrick, J. R.; Dodabalapur, A.; Torsi, L.; Lovinger, A, J.; Kwock, E. W.; Miller, T. M.; Galvin, M; Berggren, Magnus; Katz, H. E.

    1997-01-01

    Thin polycrystalline films of perylenetetracarboxylic dianyhydride (PTCDA), an organic molecular solid, exhibits substantial anisotropies in its electronic transport properties. Only electrons transport in the directions along molecular planes, while mainly holes transport in the direction normal to molecular planes. A series of measurements on both field effect transistors with PTCDA active layers and light emitting diodes with PTCDA transport layers documents the anisotropy seen in the elec...

  17. The Cosmic Microwave Background Anisotropy Experiments

    OpenAIRE

    Smoot, George F.

    1997-01-01

    This paper reports a summary of the contents contents of six hours of lectures on the CMB anisotropy experiments given at the Strasbourg NATO school on the CMB and cosmology. (Its companion paper, astro-ph/9705101 reports the lectures on the CMB spectrum.) A context is set as a bridge from the theoretical CMB anisotropy lectures and the experimental situation. The COBE DMR results are reveiwed in detail and as pioneer for future space missions. Current and planned experiments are discussed in...

  18. CMB Anisotropies: Their Discovery and Utilization

    OpenAIRE

    Smoot, George F.

    2008-01-01

    This article is a written and modified version of a talk presented at the conference `A Century of Cosmology' held at San Servolo, Venice, Italy, in August 2007. The talk focuses on some of the cosmology history leading to the discovery and exploitation of Cosmic Microwave Background (CMB) Radiation anisotropies. We have made tremendous advances first in the development of the techniques to observe these anisotropies and in observing and interpreting them to extract their contained cosmologic...

  19. Magnetic anisotropy in rare-earth metals

    DEFF Research Database (Denmark)

    Nielsen, Mourits; Bjerrum Møller, Hans; Lindgård, Per-Anker; Mackintosh, A.R.

    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...... entirely the result of magnetoelastic effects. The temperature dependences of the anisotropy parameters have been deduced from the results...

  20. Seismic anisotropy in the Sumatra subduction zone

    OpenAIRE

    R. Collings; Rietbrock, A.; Lange, Dietrich; F. Tilmann; S. Nippress; D. Natawidjaja

    2013-01-01

    An important tool for understanding deformation occurring within a subduction zone is the measurement of seismic anisotropy through observations of shear wave splitting (SWS). In Sumatra, two temporary seismic networks were deployed between December 2007 and February 2009, covering the fore arc between the fore-arc islands to the back arc. We use SKS and local SWS measurements to determine the type, amount, and location of anisotropy. Local SWS measurements from the fore-arc islands exhibit t...

  1. Does deformation saturate seismic anisotropy?

    Science.gov (United States)

    Tatham, D. J.; Lloyd, G. E.; Butler, R. W.; Casey, M.

    2006-12-01

    The progressive simple shear deformation that characterizes ductile fault zones in the crust involves both rotation and intensification of the strain ellipsoid. These mathematic predictions have been confirmed repeatedly by finite strain determinations in outcrop studies of natural shear zones and used to test geodynamic models of mountain belts. Seismic anisotropy (SA) methods offer the opportunity to pursue these approaches in situ. First however, we must calibrate the magnitude and orientation of the SA ellipsoid against naturally deformed tectonites of known strain state and microstructure. Here we present data from a field analogue of mafic ductile crust in an amphibolite-facies shear zone developed in a deformed mafic dyke embedded within the Lewisian Gneiss (Badcall, NW Scotland). Deflection of pre-existing linear and planar elements and attenuation of the dyke into the shear zone are used to determine the strain gradient. Specimens collected along this gradient were used to establish the geometric fabric intensity defined by different minerals (hornblende grain alignment and ellipticity of plagioclase clots). Finally, petrophysical properties were calculated for the specimens using the SEM-EBSD measured populations of lattice preferred orientations (LPO) for all mineral phases. It is the hornblende-plagioclase LPO, combined in their modal proportions and modulated by the individual mineral single crystal elastic properties, which define the SA profile across the shear zone. Hornblende develops a strong preferred dimensional orientation and hence LPO at shear strains of about 2, whereas the plagioclase LPO remains close to random regardless of bulk strain. The modelled SA of the samples is dominated therefore by the amphibole LPO. Although the values of bulk shear strain vary across the shear zone (0 at the margins to greater than 12 in the centre), the calculated intensity of SA saturates at a shear strain of about 2. These results, if typical of large

  2. Friction anisotropy in boronated graphite

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, N., E-mail: niranjan@igcar.gov.in [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam (India); Radhika, R. [Crystal Growth Centre, Anna University, Chennai (India); Kozakov, A.T. [Research Institute of Physics, Southern Federal University, Rostov-on-Don (Russian Federation); Pandian, R. [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam (India); Chakravarty, S. [UGC-DAE CSR, Kalpakkam (India); Ravindran, T.R.; Dash, S.; Tyagi, A.K. [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam (India)

    2015-01-01

    Graphical abstract: - Highlights: • Friction anisotropy in boronated graphite is observed in macroscopic sliding condition. • Low friction coefficient is observed in basal plane and becomes high in prismatic direction. • 3D phase of boronated graphite transformed into 2D structure after friction test. • Chemical activity is high in prismatic plane forming strong bonds between the sliding interfaces. - Abstract: Anisotropic friction behavior in macroscopic scale was observed in boronated graphite. Depending upon sliding speed and normal loads, this value was found to be in the range 0.1–0.35 in the direction of basal plane and becomes high 0.2–0.8 in prismatic face. Grazing-incidence X-ray diffraction analysis shows prominent reflection of (0 0 2) plane at basal and prismatic directions of boronated graphite. However, in both the wear tracks (1 1 0) plane become prominent and this transformation is induced by frictional energy. The structural transformation in wear tracks is supported by micro-Raman analysis which revealed that 3D phase of boronated graphite converted into a disordered 2D lattice structure. Thus, the structural aspect of disorder is similar in both the wear tracks and graphite transfer layers. Therefore, the crystallographic aspect is not adequate to explain anisotropic friction behavior. Results of X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy shows weak signature of oxygen complexes and functional groups in wear track of basal plane while these species dominate in prismatic direction. Abundance of these functional groups in prismatic plane indicates availability of chemically active sites tends to forming strong bonds between the sliding interfaces which eventually increases friction coefficient.

  3. Friction anisotropy in boronated graphite

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Friction anisotropy in boronated graphite is observed in macroscopic sliding condition. • Low friction coefficient is observed in basal plane and becomes high in prismatic direction. • 3D phase of boronated graphite transformed into 2D structure after friction test. • Chemical activity is high in prismatic plane forming strong bonds between the sliding interfaces. - Abstract: Anisotropic friction behavior in macroscopic scale was observed in boronated graphite. Depending upon sliding speed and normal loads, this value was found to be in the range 0.1–0.35 in the direction of basal plane and becomes high 0.2–0.8 in prismatic face. Grazing-incidence X-ray diffraction analysis shows prominent reflection of (0 0 2) plane at basal and prismatic directions of boronated graphite. However, in both the wear tracks (1 1 0) plane become prominent and this transformation is induced by frictional energy. The structural transformation in wear tracks is supported by micro-Raman analysis which revealed that 3D phase of boronated graphite converted into a disordered 2D lattice structure. Thus, the structural aspect of disorder is similar in both the wear tracks and graphite transfer layers. Therefore, the crystallographic aspect is not adequate to explain anisotropic friction behavior. Results of X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy shows weak signature of oxygen complexes and functional groups in wear track of basal plane while these species dominate in prismatic direction. Abundance of these functional groups in prismatic plane indicates availability of chemically active sites tends to forming strong bonds between the sliding interfaces which eventually increases friction coefficient

  4. Probing the Frontiers of QCD

    CERN Document Server

    Horowitz, W A

    2010-01-01

    With the energy scales opened up by RHIC and LHC the age of high-pT physics is upon us. This has created new opportunities and novel mysteries, both of which will be explored in this thesis. The possibility now exists experimentally to exploit these high momentum particles to uniquely probe the unprecedented state of matter produced in heavy ion collisions. At the same time naive theoretical expectations have been dashed by data. The first puzzle we confront is that of the enormous intermediate-pT azimuthal anisotropy, or v2, of jets observed at RHIC. The second puzzle is the surprisingly similar suppression of light mesons and nonphotonic electrons, which precludes perturbative predictions predicated on gluon bremsstrahlung radiation as the dominant energy loss channel. Near qualitative agreement results from including collisional energy loss and integrating over the fluctuating jet pathlengths. Another conjecture for heavy quark energy loss comes via explicit construction using the AdS/CFT correspondence; t...

  5. On the problem of electron-induced anisotropy effect in As{sub 2}S{sub 3}-based glasses

    Energy Technology Data Exchange (ETDEWEB)

    Balitska, V.O.; Shpotyuk, O.I. E-mail: karat@ipm.lviv.ua

    2000-05-02

    Effect of electron-induced anisotropy was observed in glassy As{sub 2}S{sub 3}-based samples irradiated by accelerated electrons (E=2.8 MeV) in the perpendicular plane to the probe light. Spectral and compositional dependences of this effect and its time stability at room temperature were discussed. It was supposed that the microstructural mechanism of the anisotropy effect was connected with electron-induced formation of new oriented (relatively to the electron flow) defects in the form of broken chemical bonds.

  6. Velocity anisotropy in tidally limited star clusters

    CERN Document Server

    Tiongco, Maria; Varri, Anna Lisa

    2015-01-01

    We explore the long-term evolution of the anisotropy in the velocity space of star clusters starting with different structural and kinematical properties. We show that the evolution of the radial anisotropy strength and its radial variation within a cluster contain distinct imprints of the cluster initial structural properties, dynamical history, and of the external tidal field of its host galaxy. Initially isotropic and compact clusters with small initial values of the ratio of the half-mass to Jacobi radius, $r_h/r_J$, develop a strong radial anisotropy during their long-term dynamical evolution. Many clusters, if formed with small values of $r_h/r_J$, should now be characterized by a significant radial anisotropy increasing with the distance from the cluster centre, reaching its maximum at a distance between 0.2 $r_J$ and 0.4 $r_J$, and then becoming more isotropic or mildly tangentially anisotropic in the outermost regions. A similar radial variation of the anisotropy can also result from an early violent...

  7. The expected anisotropy in solid inflation

    International Nuclear Information System (INIS)

    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 F2 gives frozen and scale invariant vector perturbations on superhorizon scales

  8. Surface anisotropy characterisation with meteosat observations

    Science.gov (United States)

    Lattanzio, A.; Govaerts, Y. M.; Pinty, B.

    Surface albedo, or more precisely Directional Hemispherical Reflectance (DHR), is the integral the Bi-directional Reflectance Factor (BRF) of the surface over all angles of the upward hemisphere. The retrieval of the DHR trough space observations requires accounting for the scattering and absorption processes in the atmosphere as well as for the angular anisotropy of the surface, the two systems being radiatively coupled. The accuracy achieved in the albedo estimation depends thus on the density of the angular sampling and the reliability of the atmospheric correction. Pinty et al. demonstrated the possibility to derive reliable surface albedo from observations acquired by Meteosat, the European meteorological geostationary satellite. The purpose of this presentation is to analyse the accuracy of this new Meteosat Surface Albedo (MSA) product, including the effects due to instrument changes and associated calibration uncertainties. In particular, the consistency of the surface anisotropy characterisation is examined in detail. To this end, observations acquired by two adjacent geostationary spacecrafts, i.e., Meteosat-7 and Meteosat-5 have been processed with the MSA algorithm. These satellites are located respectively at 0 and 63 degrees East. Data acquired by these two instruments overlap over a large area encompassing most of Africa and the Arabian Peninsula. The consistency of the surface anisotropy retrieval is evaluated through a reconstruction of the Meteosat-5 (-7) observations with the Meteosat-7 (-5) surface anisotropy characterisation. No differences larger than the calibration uncertainties have been found, which indicates that the MSA algorithm accounts correctly for the surface anisotropy and instrument differences.

  9. Large Friction Anisotropy of a Polydiacetylene Monolayer

    International Nuclear Information System (INIS)

    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

  10. Measurements of magnetic anisotropy in sickle cells

    International Nuclear Information System (INIS)

    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)

  11. Hydraulic Conductivity Anisotropy of Heterogeneous Unsaturated Soils

    Science.gov (United States)

    Sun, Dongmin; Zhu, Jianting

    2010-05-01

    The effects of saturation degree (or capillary pressure) on hydraulic conductivity anisotropy in unsaturated soils have not been fully understood. This study developed an approach based on a conceptualization of combining the neural network based pedo-transfer function (PTF) results with the thin layer concept to explore the capillary pressure-dependent anisotropy in relation to soil texture and soil bulk density. The main objective is to examine how anisotropy characteristics are related to the relationships between hydraulic parameters and the basic soil attributes such as texture and bulk density. The hydraulic parameters are correlated with the texture and bulk density based on the pedo-transfer function (PTF) results. It is demonstrated that non-monotonic behavior of the unsaturated soil anisotropy in relation to the capillary pressure is only observed when the saturated hydraulic conductivity and the shape parameter are both related to the mean particle diameter. When only one hydraulic parameter is related to the grain diameter or when both are not related to the same attribute simultaneously, the unsaturated soil anisotropy increases monotonically with the increasing capillary pressure head. Therefore, it is suggested that this behavior is mainly due to the coupled dependence of the layer saturated hydraulic conductivities and the shape factors on the texture and bulk density. The correlation between the soil grain diameter and bulk density decreases the anisotropy effects of the unsaturated layered soils. The study illustrates that the inter-relationships of soil texture, bulk density, and hydraulic properties may cause vastly different characteristics of anisotropic unsaturated soils.

  12. Electromagnetic surface wave induced magnetic anisotropy

    International Nuclear Information System (INIS)

    Femtosecond laser induced electromagnetic surface waves, supported by a gold overlayer on top of a magnetic iron garnet (IG) single-crystalline film, are demonstrated to induce a change in the magnetic anisotropy of the IG. This effect is found to be similar to the previously reported photo-induced magnetic anisotropy in this material. However, its dependence on the polarization of the light and orientation of the magnetization is found to be different. This electromagnetic surface wave control of the spins opens new interesting possibilities for all-optical ultrafast control of the magnetization at a nanometre length scale.

  13. Electromagnetic surface wave induced magnetic anisotropy

    Energy Technology Data Exchange (ETDEWEB)

    Le Guyader, L [Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland); Kirilyuk, A; Rasing, Th [IMM, Radboud University Nijmegen, Toernooiveld 1, 6525ED Nijmegen (Netherlands); Smolyaninov, I I [Department of Electrical and Computer Engineering, University of Maryland, College Park, MD (United States)], E-mail: loic.leguyader@psi.ch

    2009-05-21

    Femtosecond laser induced electromagnetic surface waves, supported by a gold overlayer on top of a magnetic iron garnet (IG) single-crystalline film, are demonstrated to induce a change in the magnetic anisotropy of the IG. This effect is found to be similar to the previously reported photo-induced magnetic anisotropy in this material. However, its dependence on the polarization of the light and orientation of the magnetization is found to be different. This electromagnetic surface wave control of the spins opens new interesting possibilities for all-optical ultrafast control of the magnetization at a nanometre length scale.

  14. Anisotropy of the Topopah Spring Member Tuff

    International Nuclear Information System (INIS)

    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

  15. Orientational dynamics of ferrofluids with finite magnetic anisotropy of the particles: relaxation of magneto-birefringence in crossed fields.

    Science.gov (United States)

    Raikher, Yu L; Stepanov, V I; Bacri, J-C; Perzynski, R

    2002-08-01

    Dynamic birefringence in a ferrofluid subjected to crossed bias (constant) and probing (pulse or ac) fields is considered, assuming that the nanoparticles have finite magnetic anisotropy. This is done on the basis of the general Fokker-Planck equation that takes into account both internal magnetic and external mechanical degrees of freedom of the particle. We describe the orientation dynamics in terms of the integral relaxation time of the macroscopic orientation order parameter. To account for an arbitrary relation between the bias (external) and anisotropy (internal) fields, an interpolation expression for the integral relaxation time is proposed and justified. A developed description is used to interpret the measurements of birefringence relaxation in magnetic fluids with nanoparticles of high (cobalt ferrite) and low (maghemite) anisotropy. The proposed theory appears to be in full qualitative agreement with all the experimental data available. PMID:12241160

  16. 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.

  17. Developments of UTDefect: Rough rectangular cracks, anisotropy, etc

    International Nuclear Information System (INIS)

    for the strip-like crack, so the immersion probes can likewise be used for all defects except the strip-like crack. As a new option the exact integration can also be used for the contact probes for all defects except the strip-like crack. The surface-breaking strip-like crack was earlier treated as the limit of an interior crack. This is questionable as it leads to an incorrect behaviour at the crack mouth which is forced to be closed. By a new expansion of the crack opening displacement the surface breaking crack has been treated in a more realistic way. By example it is seen that this new way leads to different predictions except in the most common situation when the corner effect is dominating. A new addition in UTDefect is that the component can now be viscoelastic so that damping is modelled. This is specified as the drop in dB per wavelength. It should be noticed that this damping model does not include grain scattering, meaning that no noise mechanism is included. In parallel with the development of UTDefect, which is valid for an isotropic component, there has been on-going work for an anisotropic component. Mainly due to computer storage requirements, it has been decided not to include an anisotropic component into, UTDefect. This is instead an independent program which at present only contains one defect type, namely the strip-like crack, possibly with a planar back surface. Both the crack and the back surface may be arbitrarily tilted and skewed. The anisotropy in the component is assumed to be orthotropic (with transverse isotropy as a special case), but can be arbitrarily oriented (specified by three Euler angles)

  18. Is there evidence for anomalous dipole anisotropy in the large-scale structure?

    CERN Document Server

    Bengaly,, C A P; Alcaniz, J S; Xavier, H S; Novaes, C P

    2016-01-01

    We probe the anisotropy of the large-scale structure (LSS) with the WISE-2MASS catalogue. This analysis is performed by a directional comparison of the galaxy number counts through the entire celestial sphere once systematic effects, such as star-galaxy separation and foregrounds contamination, are properly taken into account. We find a maximal hemispherical asymmetry whose dipolar component is $A = 0.0507 \\pm 0.0014$ toward the $(l,b) = (323^{\\circ},-5^{\\circ})$ direction. This result is consistent with previous estimations of our proper motion in low and intermediate redshifts, as those carried out with Type Ia Supernovae and similar LSS catalogues.Furthermore, this dipole amplitude obtained is statistically consistent with mock catalogues simulated according to the $\\Lambda$CDM matter density expected fluctuations, in addition to observational biases such as the incomplete celestial coverage, anisotropic sky exposure. Our results suggest, therefore, that there is no strong evidence for anomalous anisotropy...

  19. Strain-activated structural anisotropy in BaFe2As2

    Science.gov (United States)

    Chen, Xiang; Harriger, Leland; Sefat, Athena; Birgeneau, R. J.; Wilson, Stephen D.

    2016-04-01

    High-resolution single crystal neutron diffraction measurements are presented probing the magnetostructural response to uniaxial pressure in the iron pnictide parent system BaFe2As2 . Scattering data reveal a strain-activated, anisotropic broadening of nuclear Bragg reflections, which increase upon cooling below the resolvable onset of global orthorhombicity. This anisotropy in lattice coherence continues to build until a lower temperature scale—the first-order onset of antiferromagnetism—is reached. Our data suggest that antiferromagnetism and strong magnetoelastic coupling drive the strain-activated lattice response in this material and that the development of anisotropic lattice correlation lengths under strain is a possible origin for the high temperature transport anisotropy in this compound.

  20. Morphological diagram of diffusion driven aggregate growth in plane: Competition of anisotropy and adhesion

    Science.gov (United States)

    Menshutin, A. Yu.; Shchur, L. N.

    2011-09-01

    Two-dimensional structures grown with Witten and Sander algorithm are investigated. We analyze clusters grown off-lattice and clusters grown with antenna method with N=3,4,5,6,7 and 8 allowed growth directions. With the help of variable probe particles technique we measure fractal dimension of such clusters D(N) as a function of their size N. We propose that in the thermodynamic limit of infinite cluster size the aggregates grown with high degree of anisotropy ( N=3,4,5) tend to have fractal dimension D equal to 3/2, while off-lattice aggregates and aggregates with lower anisotropy ( N>6) have D≈1.710. Noise-reduction procedure results in the change of universality class for DLA. For high enough noise-reduction value clusters with N⩾6 have fractal dimension going to 3/2 when N→∞.

  1. Modeling of current characteristics of Segmented Langmuir Probe on DEMETER

    Science.gov (United States)

    Imtiaz, Nadia; Marchand, Richard

    2012-10-01

    We model current characteristics of a Segmented Langmuir probe mounted on DEMETER satellite. The probe is used to measure electron density and temperature in the ionosphere on DEMETER at altitudes of 700 km.It also serves as a Mach probe and used to measure the plasma flow velocities in satellite frame of reference.The probe is partitioned into seven segments: six electrically insulated spherical caps and a Guard electrode (sphere). Comparisons are made between the model predictions and measurements for characteristics of various segments for actual ionospheric plasma conditions encountered along DEMETER orbit. Segment characteristics are computed numerically with PTetra, a 3 D PIC simulation code. The model accounts for several physical effects of importance in the interaction of spacecraft with the space environment e.g. satellite charging, photoelectron and secondary electron emission. The supersonic flow of plasma results in different characteristics for different segments of the probe. This anisotropy in turn can be used to infer the velocity of the background plasma. It is observed in that a positive bias can significantly modify plasma sheath region and wake formation around the probe.Computed characteristics and their angular anisotropy are compared with measurements.

  2. Temperature Anisotropies in a Universe with Global Defects

    OpenAIRE

    Coulson, David

    1994-01-01

    We present a technique of calculating microwave anisotropies from global defects in a reionised universe. We concentrate on angular scales down to one degree where we expect the nongaussianity of the temperature anisotropy in these models to become apparent.

  3. 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 enti...

  4. 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.

  5. What we learn from CMB Anisotropies

    CERN Document Server

    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.

  6. Angular anisotropy representation by probability tables

    International Nuclear Information System (INIS)

    In this paper, we improve point-wise or group-wise angular anisotropy representation by using probability tables. The starting point of this study was to give more flexibility (sensitivity analysis) and more accuracy (ray effect) to group-wise anisotropy representation by Dirac functions, independently introduced at CEA (Mao, 1998) and at IRSN (Le Cocq, 1998) ten years ago. Basing ourselves on our experience of cross-section description, acquired in CALENDF (Sublet et al., 2006), we introduce two kinds of moment based probability tables, Dirac (DPT) and Step-wise (SPT) Probability Tables where the angular probability distribution is respectively represented by Dirac functions or by a step-wise function. First, we show how we can improve equi-probable cosine representation of point-wise anisotropy by using step-wise probability tables. Then we show, by Monte Carlo techniques, how we can obtain a more accurate description of group-wise anisotropy than the one usually given by a finite expansion on a Legendre polynomial basis (that can induce negative values) and finally, we describe it by Dirac probability tables. This study is carried out in the framework of GALILEE project R and D activities (Coste-Delclaux, 2008). (authors)

  7. Anisotropy of Magnetic Properties in Textured Materials

    OpenAIRE

    J. A. Szpunar

    1989-01-01

    A short survey is presented of techniques and methods used to correlate the texture with the magnetic anisotropy of various properties of soft and hard magnetic materials. Also, examples of magnetic materials are discussed with emphasis on techniques of processing which optimize the texture.

  8. Azimuthal anisotropy of jet quenching at LHC

    Indian Academy of Sciences (India)

    I P Lokhtin; S V Petrushanko; L I Sarycheva; A M Snigirev

    2003-05-01

    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.

  9. Impact of rock anisotropy on fracture development

    Institute of Scientific and Technical Information of China (English)

    Lianbo Zeng; Jiyong Zhao; Shengju Zhu; Weiliang Xiong; Yonghong He; Jianwen Chen

    2008-01-01

    Experiments on uniaxial and triaxial rock mechanics and rock acoustic emissions have been conducted for research on the impact of rock anisotropy on the development of the fractures of different directions by taking as an example the ultra-low-permeability sandstone reservoir in the Upper Triassic Yanchang Formation within the Ordos Basin. The experimental results prove the existence of anisotropy of the rock mechanical property in the different directions on the plane, which is the chief reason for the production of impacts on the development of different assemblages of fractures in the geological periods. The rock anisotropy usually restricts the development of one assemblage of conjugate shear fractures. The fractures in the Yanchang Formation within the Ordos Basin are mainly shear fractures that formed under two tectonic actions. Theoretically, here, four assemblages of shear fractures should have developed, but due to the effect of a strong rock anisotropy, in each period one assemblage of fractures chiefly developed. Thus, two assemblages of fractures are usually developed in every part at present.

  10. 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…

  11. Tuning the Magnetic Anisotropy of Single Molecules.

    Science.gov (United States)

    Heinrich, Benjamin W; Braun, Lukas; Pascual, Jose I; Franke, Katharina J

    2015-06-10

    The magnetism of single atoms and molecules is governed by the atomic scale environment. In general, the reduced symmetry of the surrounding splits the d states and aligns the magnetic moment along certain favorable directions. Here, we show that we can reversibly modify the magnetocrystalline anisotropy by manipulating the environment of single iron(II) porphyrin molecules adsorbed on Pb(111) with the tip of a scanning tunneling microscope. When we decrease the tip-molecule distance, we first observe a small increase followed by an exponential decrease of the axial anisotropy on the molecules. This is in contrast to the monotonous increase observed earlier for the same molecule with an additional axial Cl ligand ( Nat. Phys. 2013 , 9 , 765 ). We ascribe the changes in the anisotropy of both species to a deformation of the molecules in the presence of the attractive force of the tip, which leads to a change in the d level alignment. These experiments demonstrate the feasibility of a precise tuning of the magnetic anisotropy of an individual molecule by mechanical control. PMID:25942560

  12. Ultrasonic evaluation of local biological tissue anisotropy

    Czech Academy of Sciences Publication Activity Database

    Tokar, Daniel; Převorovský, Zdeněk; Hradilová, Jana

    Brno: University of Technology, 2014. s. 26-27. ISBN 978-80-214-5019-6. [European Conference on Non-Destructive Testing (ECNDT 2014) /11./. 06.10.2014-10.10.2014, Praha] Institutional support: RVO:61388998 Keywords : ultrasonic testing (UT) * signal processing * medical application * anisotropy Subject RIV: BI - Acoustics

  13. Surface stress anisotropy of Ge(001)

    NARCIS (Netherlands)

    Middel, M.T.; Zandvliet, H.J.W.; Poelsema, Bene

    2002-01-01

    By analyzing the equilibrium shape of vacancy islands on the Ge(001) surface we have determined the surface stress anisotropy, i.e., the difference between the compressive stress component along the substrate dimer rows and the tensile stress component perpendicular to the substrate dimer rows. In o

  14. Gaussian Anisotropy In Strange Quark Stars

    CERN Document Server

    Panahi, H; Eghdami, I

    2015-01-01

    In this paper for studying the anisotropic strange quark stars, we assume that the radial pressure inside the anisotropic star is a superposition of pressure in an isotropic case plus a Gaussian perturbation term. Considering a proportionality between electric charge density and the density of matter, we solve the TOV equation for different cases numerically. Our results indicate that anisotropy increases the maximum mass $M_{max}$ and also its corresponding radius $R$ for a typical strange quark star. According to our calculations, an anisotropy amplitude of $A=3\\times10^{33}Nm^{-2}$ with a standard deviation of $\\sigma=3\\times10^{3}m$ leads to a neutron star of 1.97$M_{\\odot}$. Furthermore, electric charge not only increases the maximum mass and its corresponding radius, but also raises up the anisotropy factor. We can see that the tangential pressure $p_{t}$ and anisotropy factor $\\Delta$ unlike the radial pressure $p_{r}$ have a maximum on the surface and this maximum increases by adding electric charge e...

  15. Gold Spiky Nanodumbbells: Anisotropy in Gold Nanostars

    OpenAIRE

    Novikov, Sergey M.; Sánchez-Iglesias, Ana; Schmidt, Mikołaj K.; Chuvilin, Andrey; Aizpurua, Javier; Grzelczak, Marek; Liz-Marzán, Luis M.

    2013-01-01

    A new type of gold nanoparticle—called “spiky nanodumbbells”—is introduced. These particles combine the anisotropy of nanorods with sharp nanoscale features of nanostars, which are important for SERS applications. Both the morphology and the optical response of the particles are characterized in detail, and the experimental results are compared with FDTD simulations, showing good agreement.

  16. Competing anisotropies in holmium-erbium superlattices

    DEFF Research Database (Denmark)

    Simpson, J.A.; McMorrow, D.F.; Cowley, R.A.; Jehan, D.A.; Ward, R.C.C.; Wells, M.R.; Clausen, K.N.

    1994-01-01

    The effect of competing crystal-field anisotropies on magnetic order has been investigated in a series of Ho/Er superlattices. For temperatures in the interval T(N)(Er) less-than-or-equal-to T less-than-or-equal-to T(N)(Ho) the Ho basal-plane order propagates coherently through the paramagnetic E...

  17. 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...

  18. Anisotropy and texture. Studies in magnetic media

    International Nuclear Information System (INIS)

    The rapid development of magnetic materials for recording media applications increased the demands for new and more precise experimental investigation techniques. In respect with these demands, this project is focused on experimental analyses of advanced particulate media and magnetic thin film samples. A new extended rotational remanence technique for anisotropy field measurements was developed. The technique is suitable for samples that contain aligned or partially aligned particles and provides both: in-plane anisotropy field distributions and the in-plane anisotropy field. This technique was also extended to out-of-plane anisotropy field measurements. Rotational hysteresis was introduced as an alternative method for anisotropy field measurements. This applies well in the case of samples without texture or samples having very small magnetic moment (i.e. thin films). The two techniques for anisotropy field measurement compare well and the experimental results were interpreted in terms of inter-particles interactions. Two measurement methods for determination of the demagnetizing field acting perpendicular to a sample plane were also developed. The first method is based on the in-plane and out-of-plane anisotropy field determination using an extended rotational remanence technique. The second method can provide the demagnetizing field starting from in-plane and out-of-plane transverse hysteresis loops. Comparison between the results from the two methods showed good agreement. Furthermore, the demagnetizing field values were used to calculate the magnetic coating thickness, so the two methods provide a non-destructive method for magnetic thickness measurements in film samples. The in-plane easy axis distribution (EAD) was experimentally determined using vector VSM techniques. Correlations between in-plane tape texture and magnetic thickness were obtained for a series of advanced MP tapes. A theoretical approach was used in order to relate the orientation ratio to

  19. Multi-scale characterization of topographic anisotropy

    Science.gov (United States)

    Roy, S. G.; Koons, P. O.; Osti, B.; Upton, P.; Tucker, G. E.

    2016-05-01

    We present the every-direction variogram analysis (EVA) method for quantifying orientation and scale dependence of topographic anisotropy to aid in differentiation of the fluvial and tectonic contributions to surface evolution. Using multi-directional variogram statistics to track the spatial persistence of elevation values across a landscape, we calculate anisotropy as a multiscale, direction-sensitive variance in elevation between two points on a surface. Tectonically derived topographic anisotropy is associated with the three-dimensional kinematic field, which contributes (1) differential surface displacement and (2) crustal weakening along fault structures, both of which amplify processes of surface erosion. Based on our analysis, tectonic displacements dominate the topographic field at the orogenic scale, while a combination of the local displacement and strength fields are well represented at the ridge and valley scale. Drainage network patterns tend to reflect the geometry of underlying active or inactive tectonic structures due to the rapid erosion of faults and differential uplift associated with fault motion. Regions that have uniform environmental conditions and have been largely devoid of tectonic strain, such as passive coastal margins, have predominantly isotropic topography with typically dendritic drainage network patterns. Isolated features, such as stratovolcanoes, are nearly isotropic at their peaks but exhibit a concentric pattern of anisotropy along their flanks. The methods we provide can be used to successfully infer the settings of past or present tectonic regimes, and can be particularly useful in predicting the location and orientation of structural features that would otherwise be impossible to elude interpretation in the field. Though we limit the scope of this paper to elevation, EVA can be used to quantify the anisotropy of any spatially variable property.

  20. Synthesis of transport layers with controlled anisotropy and application thereof to study proton exchange membrane fuel cell performance

    Science.gov (United States)

    Todd, Devin; Mérida, Walter

    2016-04-01

    We report on a novel method for the synthesis of fibre-based proton exchange membrane (PEM) fuel cell porous transport layers (PTLs) with controllable fibre alignment. We also report the first application of such layers as diagnostics tools to probe the effect of within-plane PTL anisotropy upon PEM fuel cell performance. These structures are realized via adaptation of electrospinning technology. Electrospun layers with progressive anisotropy magnitude are produced and evaluated. This novel approach is distinguished from the state-of-the-art because an equivalent study using commercially available materials is impossible due to lack of structurally similar substrates with different anisotropies. The anisotropy is visualized via scanning electron microscopy, and quantified using electrical resistivity. The capacity is demonstrated to achieve fibre alignment, and the associated impact on transport properties. A framework is presented for assessing the in-situ performance, whereby transport layer orientation versus bipolar plate flow-field geometry is manipulated. While an effect upon the commercial baseline cannot be discerned, electrospun transport layers with greater anisotropy magnitude suggest greater sensitivity to orientation; where greater performance is obtained with fibres cross-aligned to flow-field channels. Our approach of electrospun transport enables deterministic structures by which fuel cell performance can be explained and optimized.

  1. First-order reversal curve analysis of graded anisotropy FePtCu films

    Science.gov (United States)

    Bonanni, Valentina; Fang, Yeyu; Dumas, Randy K.; Zha, Chaolin; Bonetti, Stefano; Nogués, Josep; Åkerman, Johan

    2010-11-01

    The reversal mechanisms of graded anisotropy FePtCu films have been investigated by alternating gradient magnetometer (AGM) and magneto-optical Kerr effect (MOKE) measurements with first-order reversal curve (FORC) techniques. The AGM-FORC analysis, which clearly shows the presence of soft and hard components, is unable to resolve how these phases are distributed throughout the film thickness. MOKE-FORC measurements, which preferentially probe the surface of the film, reveal that the soft components are indeed located toward the top surface. Combining AGM-FORC with the inherent surface sensitivity of MOKE-FORC analysis allows for a comprehensive analysis of heterogeneous systems such as graded materials.

  2. Reduction of anisotropy influence and contacting effects in in-vitro bioimpedance measurements

    International Nuclear Information System (INIS)

    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.

  3. 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.

  4. Nonlinear photoinduced anisotropy and modifiable optical image display in a bacteriorhodopsin/polymer composite film

    Science.gov (United States)

    Wei, Lai; Luo, Jia; Zhu, Jiang; Lu, Ming; Zhao, You-yuan; Ma, De-wang; Ding, Jian-dong

    2007-04-01

    The nonlinear photoinduced anisotropy with large birefringence in a bacteriorhodopsin/polymer composite (bR/PC) film was observed. The contrast ratio, a ratio of the maximum to the minimum intensity of transmitted probe light through the bR/PC film within the linear gray scale range could reach ˜350:1. An all-optical image display in different colors was performed. The intensity of the transmitted signal could be modulated by adjusting the multibeam polarization states and intensities. Therefore, the positive image, negative image, and image erasure in display were demonstrated.

  5. Coherent control of the optical nonlinear and luminescence anisotropies in molecular thin films by multiphoton excitations.

    Science.gov (United States)

    Bidault, Sébastien; Brasselet, Sophie; Zyss, Joseph

    2004-06-01

    Photoinduced orientational distributions are implemented with one- and two-photon absorption interference in polymer films containing chromophores that exhibit luminescent and nonlinear properties. The odd- and even-order parameters of the final distribution are probed by simultaneous measurement of second-harmonic generation (SHG) and two-photon fluorescence (TPF). We show the possibility of engineering local SHG and TPF anisotropies by controlling the polarization states and intensities of the writing optical fields. Complex multipolar orders are modeled with an irreducible spherical tensor-based formalism jointly applied to the molecular polarizabilities and field tensors. PMID:15214309

  6. 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.

  7. Evolution of Tidally Truncated Globular Clusters with Anisotropy

    CERN Document Server

    Takahashi, K; Inagaki, S

    1997-01-01

    The evolution of tidally truncated globular clusters is investigated by integrating two-dimensional Fokker-Planck equation that allows the development of velocity anisotropy. We start from the isotropic Plummer model with tidal cut off and followed the evolution through the corecollapse. The heating by three-binary is included to obtain the evolution past the corecollapse. The anisotropy in velocity dispersion develops during the precollapse evolution. However, the anisotropy becomes highly depressed during the post-collapse evolution because of rapid loss of radial orbits. Maximum radial anisotropy appears just after the beginning of the expansion, and degree of anisotropy decreases slowly as the total mass of the cluster decreases. Thus it may be possible to determine the evolutionary status of a cluster if the velocity anisotropy can be measured in the sense that the postcollapse clusters always have very little degree of anisotropy. The structure of the post-collapse cluster can be well fitted to King mod...

  8. The Cosmic Microwave Background Anisotropy Experiments

    CERN Document Server

    Smoot, G F

    1997-01-01

    This paper reports a summary of the contents contents of six hours of lectures on the CMB anisotropy experiments given at the Strasbourg NATO school on the CMB and cosmology. (Its companion paper, astro-ph/9705101 reports the lectures on the CMB spectrum.) A context is set as a bridge from the theoretical CMB anisotropy lectures and the experimental situation. The COBE DMR results are reveiwed in detail and as pioneer for future space missions. Current and planned experiments are discussed in preference to reviewing already completed observations. The NASA MidEX mission MAP is discussed in some detail including figures. The ESA M3 mission Max Planck Surveyor is also reviewed in some detail though its final configuration is not yet fully settled. The recent history and current versions are presented. Tables and references for experiments are included.

  9. Anisotropies in the cosmic microwave background: Theory

    Energy Technology Data Exchange (ETDEWEB)

    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.

  10. Physics of the cosmic microwave background anisotropy

    CERN Document Server

    Bucher, Martin

    2015-01-01

    Observations of the cosmic microwave background (CMB), especially of its frequency spectrum and its anisotropies, both in temperature and in polarization, have played a key role in the development of modern cosmology and our understanding of the very early universe. We review the underlying physics of the CMB and how the primordial temperature and polarization anisotropies were imprinted. Possibilities for distinguishing competing cosmological models are emphasized. The current status of CMB experiments and experimental techniques with an emphasis toward future observations, particularly in polarization, is reviewed. The physics of foreground emissions, especially of polarized dust, is discussed in detail, since this area is likely to become crucial for measurements of the B modes of the CMB polarization at ever greater sensitivity.

  11. Anisotropy and micromagnetics in complex oxide thin films

    Science.gov (United States)

    Wynn, Thomas Andrew

    maintained a [110] easy axis. To examine magnetocrystalline effects at further reduced length scales, a series of two-micron micromagnets of various shapes and orientations were patterned via argon ion implantation into LSMO thin films deposited on a SrTiO 3 substrates. The magnetic ground state was observed via x-ray photoemission electron microscopy (X-PEEM), directly probing the competition between magnetocrystalline and shape anisotropies. Analysis of the images showed that the domain patterns consisted of a superposition of Landau and vortex patterns. A metric, named the vortex fraction, was formulated to quantify this behavior as a function of temperature and radius in circular micromagnets. Vortex fractions were used to compare X-PEEM images to simulations performed by the Object Oriented Micromagnetics Framework (OOMMF) and MuMax3 micromagnetics simulation software; results allowed for the extraction of magnetocrystalline anisotropy constant at sub-micron length scales from X-PEEM data. These results illustrate the potential for tuning magnetic ground states for future spintronic devices.

  12. Reionization Revisited: Secondary CMB Anisotropies and Polarization

    OpenAIRE

    Hu, Wayne

    1999-01-01

    Secondary CMB anisotropies and polarization provide a laboratory to study structure formation in the reionized epoch. We consider the kinetic Sunyaev-Zel'dovich effect from mildly nonlinear large-scale structure and show that it is a natural extension of the perturbative Vishniac effect. If the gas traces the dark matter to overdensities of order 10, as expected from simulations, this effect is at least comparable to the Vishniac effect at arcminute scales. On smaller scales, it may be used t...

  13. Interferometric Observation of Cosmic Microwave Background Anisotropies

    CERN Document Server

    White, M; Dragovan, M; White, Martin; Carlstrom, John E.; Dragovan, Mark

    1999-01-01

    We present a formalism for analyzing interferometric observations of Cosmic Microwave Background (CMB) anisotropy and polarization data. The formalism is based upon the ell-space expansion of the angular power spectrum favoured in recent years. Explicit discussions of maximum likelihood analysis, power spectrum reconstruction, parameter estimation, imaging and polarization are given. As an example, several calculations for the Degree Angular Scale Interferometer (DASI) and Cosmic Background Interferometer (CBI) experiments are presented.

  14. Anisotropy of SANS in metallic glasses

    International Nuclear Information System (INIS)

    SANS in metallic glasses is anisotropic and depends on the ribbon's orientation. Pd-based melt spun and Ni-based electrochemically deposited glasses exhibit different anisotropies. Both glasses contain scattering centers of the order of 40nm wide in the ribbon plane. In the melt-spun alloy, the scatterers are very thin along the thickness perpendicular to the substrate. In the deposited alloy however, the defects are long along the thickness perpendicular to the electrode

  15. Seismic Anisotropy Beneath the Sumatra Subduction Zone

    OpenAIRE

    R. Collings; Rietbrock, A.; S. Mippress; Lange, D.; D. Natawidjaja; B. Suwargadi; Frederik Tilmann

    2011-01-01

    The Sumatra subduction zone is located on the eastern side of the Sunda Arc between the Sunda Strait and the Andaman Islands, where the Indo-Australian plate is subducting beneath the Eurasian plate. An important tool in understanding the style and geometry of deformation within a subduction zone is the measurement of seismic anisotropy, through observations of shear wave splitting, which provides information about the mantle flow. In Sumatra two temporary seismic networks were deployed withi...

  16. 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

  17. 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

  18. Gaussian Anisotropy In Strange Quark Stars

    OpenAIRE

    Panahi, H.; Monadi, R.; Eghdami, I.

    2015-01-01

    In this paper for studying the anisotropic strange quark stars, we assume that the radial pressure inside the anisotropic star is a superposition of pressure in an isotropic case plus a Gaussian perturbation term. Considering a proportionality between electric charge density and the density of matter, we solve the TOV equation for different cases numerically. Our results indicate that anisotropy increases the maximum mass $M_{max}$ and also its corresponding radius $R$ for a typical strange q...

  19. Relativistic Density Functional Treatment of Magnetic Anisotropy

    OpenAIRE

    Zhang, Hongbin

    2009-01-01

    Spin-orbit coupling (SOC) reduces the spatial symmetry of ferromagnetic solids. That is, the physical properties of ferromagnetic materials are anisotropic, depending on the magnetization direction. In this thesis, by means of numerical calculations with full-relativistic density functional theory, we studied two kinds of physical properties: surface magnetic anisotropy energy (MAE) and anisotropic thermoelectric power due to Lifshitz transitions. After a short introduction to ...

  20. Anisotropy estimation properties for microstructural models

    Czech Academy of Sciences Publication Activity Database

    Beneš, Viktor; Hlawiczková, M.; Gokhale, A. M.; Vander Voort, G. F.

    2001-01-01

    Roč. 46, 2/3 (2001), s. 93-98. ISSN 1044-5803 R&D Projects: GA ČR GA201/99/0269 Grant ostatní: NSF(US) DMR-9816618 Institutional research plan: AV0Z1075907 Keywords : anisotropy * fibre system * Prokhorov distance Subject RIV: BB - Applied Statistics, Operational Research Impact factor: 0.447, year: 2001

  1. Microwave anisotropies from the Galactic halo

    CERN Document Server

    Walker, M; Mori, M; Walker, Mark; Ohishi, Michiko; Mori, Masaki

    2002-01-01

    Models in which a large fraction of the Galactic dark matter takes the form of cold gas clouds imply that there is thermal microwave emission from the Galactic dark halo. Such models can therefore be directly constrained by existing data on the microwave sky, and in particular the very sensitive observations of microwave anisotropies. To this end we have computed the anisotropy power-spectrum expected for a Galactic dark halo made of cold, dense gas clouds, including the effects of clustering with a CDM-like mass spectrum of mini-halo substructure. The power-spectrum displays two peaks: one, at l~50, is the Poisson noise for the mini-halos, and the second, much larger and at much higher l, is the Poisson noise of the individual clouds. The predicted fluctuation amplitude on degree-scales is a small (~1%) fraction of the observed (~70 micro-K) anisotropies if one considers small areas of sky at high Galactic latitude, increasing by a factor of a few for large areas of sky around 30 degrees latitude. Consequent...

  2. Measuring Anisotropies in the Cosmic Neutrino Background

    CERN Document Server

    Lisanti, Mariangela; Tully, Christopher G

    2014-01-01

    Neutrino capture on tritium has emerged as a promising method for detecting the cosmic neutrino background (CvB). We show that relic neutrinos are captured most readily when their spin vectors are anti-aligned with the polarization axis of the tritium nuclei and when they approach along the direction of polarization. As a result, CvB observatories may measure anisotropies in the cosmic neutrino velocity and spin distributions by polarizing the tritium targets. A small dipole anisotropy in the CvB 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 non-standard neutrino interactions that would induce larger anisotropies and help discriminate between Majorana versus Dirac neu...

  3. Effective surface anisotropy in polycrystalline ferromagnetic nanowires

    International Nuclear Information System (INIS)

    Highlights: • Here we make a mixing of two models. A macroscopic and a microscopic model. • The principal idea in this paper is to write the free magnetic energy for a soft magnetic cylindrical nanowire and make the comparison with our previous models. • The model is tested to determine the effective constant in Ni nanowires. - Abstract: Here we express the effective surface anisotropy for soft ferromagnetic nanowires as the function of the micro-structural behaviors. Many papers about these systems determine the reversal modes for the magnetization to explain magnetic properties of the nanowires. Our previous works related morphological structure with magnetic properties. The principal idea in this paper is to write the free magnetic energy for a soft magnetic cylindrical nanowire and make the comparison with our previous models. In this way we include the macroscopic effective anisotropy due to the disordered atoms and ignoring other microstructure terms related in our previous works. From this idea and our last model to these systems, we made an association that permit to express the effective anisotropy in function of the principal morphological characteristics of nanowires. The model is tested to determine the numerical value of the mentioned constant in Ni nanowires obtained by electrodeposition in porous anodic aluminum oxide membranes using the Transmission Electron Microscopy

  4. 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.

  5. Getting Anisotropy in the Seismic Data Processing

    Directory of Open Access Journals (Sweden)

    Edenia de la Caridad Camejo Cordero

    2013-06-01

    Full Text Available In a conventional processing of seismic data (processing of only one type of wave, P or S, to getimages for hydrocarbons exploration, an isotropic model of the earth is assumed. Studies havedemonstrated that in areas with evidences of anisotropy, the conventional process of time migrationproduces images with poor resolution or erroneous lateral localization of structural events with highinclinations, due to variations in the elastic properties according to the direction of propagation of theseismic waves. At present this topic is of great importance in seismic acquisitions because of thevast employ of the far offset (large distances source–receptor. To, compensate this negative effectsis a priority objective to improve the seismic information. To obtain the anisotropy first started from asequence of high density processing that takes into consideration the characteristics of the earth;and data can be analyzed in all volume. As a final result; getting the comparison between the timemigration stack, with the application of standard normal Moveout correction (NMO and the others,that takes into consideration the obtained anisotropy values, allowing an improvement in the continuityof the reflectors in the seismic images, and at the same time a more reliable interpretation, with theconsequent decrease of the uncertainty and the risks in the oil exploration.

  6. Detecting 3D vegetation structure with the Galileo space probe: Can a distant probe detect vegetation structure on Earth?

    CERN Document Server

    Doughty, Christopher E

    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 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 an...

  7. The intrinsic quasar luminosity function: Accounting for accretion disk anisotropy

    International Nuclear Information System (INIS)

    Quasar luminosity functions are a fundamental probe of the growth and evolution of supermassive black holes. Measuring the intrinsic luminosity function is difficult in practice, due to a multitude of observational and systematic effects. As sample sizes increase and measurement errors drop, characterizing the systematic effects is becoming more important. It is well known that the continuum emission from the accretion disk of quasars is anisotropic—in part due to its disk-like structure—but current luminosity function calculations effectively assume isotropy over the range of unobscured lines of sight. Here, we provide the first steps in characterizing the effect of random quasar orientations and simple models of anisotropy on observed luminosity functions. We find that the effect of orientation is not insignificant and exceeds other potential corrections such as those from gravitational lensing of foreground structures. We argue that current observational constraints may overestimate the intrinsic luminosity function by as much as a factor of ∼2 on the bright end. This has implications for models of quasars and their role in the universe, such as quasars' contribution to cosmological backgrounds.

  8. On the origin of the cosmic microwave background anisotropies

    CERN Document Server

    Follop, Ria; Cooray, Asantha; Abdalla, Filipe B

    2007-01-01

    Suggestions have been made that the microwave background observed by COBE and WMAP and dubbed Cosmic Microwave Background (CMB) may have an origin within our own Galaxy or Earth. To consider the signal that may be correlated with Earth, a correlate-by-eye exercise was attempted by overlaying the CMB map from Wilkinson Microwave Anisotropy Probe on a topographical map of Earth. Remarkably, several hot spots in the CMB map are found to be well aligned with either large cities on Earth or regions of high altitude. To further study the correlations between Earth and CMB, we performed a complicated cross-correlation analysis in the multipole space. The overall correlations are detected at more than 5 sigma confidence level. These results can be naively interpreted to suggest that large angular scale fluctuations in CMB are generated on Earth by a process that traces the altitude relative to a mean radius. Simply extending our analysis, we suggest that cross-correlations between CMB and any other map of a Solar sys...

  9. Theoretical analysis of a dual-probe scanning tunneling microscope setup on graphene

    OpenAIRE

    Settnes, Mikkel; Stephen R. Power; Petersen, Dirch Hjorth; Jauho, Antti-Pekka

    2014-01-01

    Experimental advances allow for the inclusion of multiple probes to measure the transport properties of a sample surface. We develop a theory of dual-probe scanning tunneling microscopy using a Green's function formalism, and apply it to graphene. Sampling the local conduction properties at finite length scales yields real space conductance maps which show anisotropy for pristine graphene systems and quantum interference effects in the presence of isolated impurities. Spectral signatures in t...

  10. Anisotropy-Guided Enantiomeric Enhancement in AlanineUsing 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 13C-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.

  11. Small-scale microwave background anisotropies due to tangled primordial magnetic fields

    CERN Document Server

    Subramanian, K; Subramanian, Kandaswamy; Barrow, John D.

    2002-01-01

    An inhomogeneous cosmological magnetic field creates vortical perturbations that survive Silk damping on much smaller scales than compressional modes. This ensures that there is no sharp cut-off in anisotropy on arc-minute scales. As we had pointed out earlier, tangled magnetic fields, if they exist, will then be a potentially important contributor to small-angular scale CMBR anisotropies. Several ongoing and new experiments, are expected to probe the very small angular scales, corresponding to multipoles with l>1000. In view of this observational focus, we revisit the predicted signals due to primordial tangled magnetic fields, for different spectra and different cosmological parameters. We also identify a new regime, where the photon mean-free path exceeds the scale of the perturbation, which dominates the predicted signal at very high l. A scale-invariant spectrum of tangled fields which redshifts to a present value B_{0}=3\\times 10^{-9} Gauss, produces temperature anisotropies at the 10 micro Kelvin level...

  12. 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....

  13. 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.

  14. Fabrication of electrodeposited Co nanowire arrays with perpendicular anisotropy

    Science.gov (United States)

    Ge, Shihui; Ma, Xiao; Li, Chao; Li, Wei

    2001-05-01

    Co nanowire arrays have been electrodeposited into polycarbonate membranes with nanosized pores at different voltages. By means of X-ray diffraction, electron diffraction, vibrating sample magnetometer, their microstructures and magnetic properties were investigated at full length. The sample prepared at -1.2 V, 250 mA/cm 2 shows perpendicular anisotropy, but the one deposited at -1.0V, 125 mA/cm 2 has no perpendicular anisotropy. This different magnetic behavior can be explained from their different microstructures. X-ray diffraction and electron diffraction evidence that the former sample is amorphous, and the latter is polycrystalline. In the polycrystalline sample, due to the competition of shape anisotropy and magnetocrystal anisotropy, the sample does not display perpendicular anisotropy. But magnetocrystal anisotropy is very small in amorphous sample, therefore, shape anisotropy plays a dominant role which leads to strong perpendicular anisotropy because of shape anisotropy. Furthermore, applying a magnetic field during deposition, Co grains will preferentially grow with c-axis along the wire axis, which also leads to strong perpendicular anisotropy.

  15. Fabrication of electrodeposited Co nanowire arrays with perpendicular anisotropy

    International Nuclear Information System (INIS)

    Co nanowire arrays have been electrodeposited into polycarbonate membranes with nanosized pores at different voltages. By means of X-ray diffraction, electron diffraction, vibrating sample magnetometer, their microstructures and magnetic properties were investigated at full length. The sample prepared at -1.2 V, 250 mA/cm2 shows perpendicular anisotropy, but the one deposited at -1.0V, 125 mA/cm2 has no perpendicular anisotropy. This different magnetic behavior can be explained from their different microstructures. X-ray diffraction and electron diffraction evidence that the former sample is amorphous, and the latter is polycrystalline. In the polycrystalline sample, due to the competition of shape anisotropy and magnetocrystal anisotropy, the sample does not display perpendicular anisotropy. But magnetocrystal anisotropy is very small in amorphous sample, therefore, shape anisotropy plays a dominant role which leads to strong perpendicular anisotropy because of shape anisotropy. Furthermore, applying a magnetic field during deposition, Co grains will preferentially grow with c-axis along the wire axis, which also leads to strong perpendicular anisotropy

  16. Analytic spectra of CMB anisotropies and polarization generated by scalar perturbations in synchronous gauge

    International Nuclear Information System (INIS)

    The temperature anisotropies and polarization of the cosmic microwave background (CMB) radiation not only serve as indispensable cosmological probes, but also provide a unique channel to detect relic gravitational waves (RGW) at very long wavelengths. Analytical studies of the anisotropies and polarization improve our understanding of various cosmic processes and help to separate the contribution of RGW from that of density perturbations. We present a detailed analytical calculation of CMB temperature anisotropies αk and polarization βk generated by scalar metric perturbations in synchronous gauge, parallel to our previous work with RGW as a generating source. This is realized primarily by an analytic time integration of Boltzmann's equation, yielding the closed forms of αk and βk. Approximations, such as the tight-coupling approximation for photons a priori to the recombination and the long-wavelength limit for scalar perturbations, are used. The residual gauge modes in scalar perturbations are analyzed and a proper joining condition of scalar perturbations at the radiation-matter equality is chosen, ensuring the continuity of energy perturbation. The resulting analytic expressions of the multipole moments of polarization aEl and of temperature anisotropies aTl are explicit functions of the scalar perturbations, recombination time, recombination width, photon-free streaming damping factor, baryon fraction, initial amplitude, primordial scalar spectral index and the running index. These results show that a longer recombination width yields higher amplitudes of polarization on large scales and more damping on small scales, and that a late recombination time shifts the peaks of CXX'l to larger angular scales. Calculations show that aEl is generated in the presence of the quadrupole α2 of temperature anisotropies via scattering, both having similar structures and being smaller than the total aTl, which consists of the contributions from the monopole, dipole

  17. Test for anisotropy in the mean of the CMB temperature fluctuation in spherical harmonic space

    Science.gov (United States)

    Kashino, Daichi; Ichiki, Kiyotomo; Takeuchi, Tsutomu T.

    2012-03-01

    The standard models of inflation predict statistically homogeneous and isotropic primordial fluctuations, which should be tested by observations. In this paper we illustrate a method to test the statistical isotropy of the mean of the cosmic microwave background temperature fluctuations in the spherical harmonic space and apply the method to the Wilkinson Microwave Anisotropy Probe seven-year observation data. A classical method to test a mean, like the simple Student’s t test, is not appropriate for this purpose because the Wilkinson Microwave Anisotropy Probe data contain anisotropic instrumental noise and suffer from the effect of the mask for the foreground emissions which breaks the statistical independence. Here we perform a band-power analysis with Monte Carlo simulations in which we take into account the anisotropic noise and the mask. We find evidence of a nonzero mean at 99.93% confidence level in a particular range of multipoles. The evidence against the zero-mean assumption as a whole is still significant at the 99% confidence level even if the fact is taken into account that we have tested multiple ranges.

  18. Determination of anisotropy to enhance the durability of natural stone

    International Nuclear Information System (INIS)

    Anisotropy is a petrophysical property of natural stone and other construction materials that determines their quality and resistance to decay due to a variety of agents, such as water. A study was conducted on nine types of stone widely used in Spain's built heritage, using six previously defined anisotropy indices. These indices can be used to determine the degree of anisotropy, which helps explain the differential decay observed in stone materials quarried in the same bed and used to build the same structure. The conclusion reached is that anisotropy should be determined in the natural stone used both to restore the architectural heritage and in new construction, since the appropriate choice of material quality ensures greater resistance to decay and, therefore, increased durability. Materials with the lowest possible anisotropy should be selected, as this property governs their hydraulic behaviour: the lower the anisotropy in a material, the better its behaviour in relation to water and the longer its durability

  19. Extending Velocity Channel Analysis for Studying Turbulence Anisotropies

    CERN Document Server

    Kandel, Dinesh; Pogosyan, Dmitri

    2016-01-01

    We extend the analysis of the fluctuations in the velocity slices of Position-Position- Velocity (PPV) spectroscopic data from Doppler broadened lines, i.e. Velocity Channel Analysis (VCA) introduced by Lazarian & Pogosyan (2000), to study anisotropy of the underlying velocity and density turbulence statistics that arises from the presence of magnetic field. In particular, we study analytically how the measurable anisotropy of the statistics of the channel map fluctuations changes with the thickness of velocity channels. In agreement with the earlier VCA studies we find that the anisotropy of the thick channels reflects the anisotropy of the density field, while the relative contribution of density and velocity fluctuations to the thin velocity channels depends on the density spectral slope. We show that the anisotropies arising from Alfven, slow and fast modes are different, in particular, the anisotropy in PPV created by fast modes is opposite to that created by Alfven and slow modes and this can be use...

  20. Low-temperature magnetic anisotropy in micas and chlorite

    DEFF Research Database (Denmark)

    Biedermann, Andrea R.; Bender Koch, Christian; Lorenz, Wolfram E A;

    2014-01-01

    use the magnetic anisotropy to understand a rock fabric, it is necessary to identify the minerals responsible for the magnetic anisotropy. Techniques have been developed to separate contributions of the ferrimagnetic, antiferromagnetic, paramagnetic, and diamagnetic susceptibilities to the anisotropy......Phyllosilicates, such as micas and chlorite, are common rock-forming minerals and often show preferred orientation in deformed rocks. In combination with single-crystal anisotropy, this leads to anisotropy of physical properties in the rock, such as magnetic susceptibility. In order to effectively...... of magnetic susceptibility. Because diamagnetic and paramagnetic susceptibility are both linearly dependent on field, separation of the anisotropic contributions requires understanding how the degree of anisotropy of the paramagnetic susceptibility changes as a function of temperature. Note that...

  1. Lichtinduzierte Generierung und Charakterisierung optischer Anisotropie. - [überarb. Diss.

    OpenAIRE

    Jung, Carl Christoph

    2005-01-01

    Eine Nutzung der optischen Anisotropie dünner Schichten ist vor allem für die Displaytechnologie, die optische Datenspeicherung und für optische Sicherheitselemente von hoher Bedeutung. Diese Doktorarbeit befasst sich mit theoretischen und experimentellen Untersuchung von dreidimensionaler Anisotropie und dabei insbesondere mit der Untersuchung von lichtinduzierter dreidimensionaler Anisotropie in organischen dünnen Polymer-Schichten. Die gewonnenen Erkentnisse und entwickelten Methoden könne...

  2. Anisotropies in the Gravitational-Wave Stochastic Background

    CERN Document Server

    Olmez, S; Siemens, X

    2011-01-01

    We consider anisotropies in the stochastic background of gravitational-waves (SBGW) arising from random fluctuations in the number of gravitational-wave sources. We first develop the general formalism which can be applied to different cosmological or astrophysical scenarios. We then apply this formalism to calculate the anisotropies of SBGW associated with the fluctuations in the number of cosmic string loops, considering both cosmic string cusps and kinks. We calculate the anisotropies as a function of angle and frequency.

  3. Anisotropies in the Gravitational-Wave Stochastic Background

    OpenAIRE

    Olmez, S.; Mandic, V.; Siemens, X.

    2011-01-01

    We consider anisotropies in the stochastic background of gravitational-waves (SBGW) arising from random fluctuations in the number of gravitational-wave sources. We first develop the general formalism which can be applied to different cosmological or astrophysical scenarios. We then apply this formalism to calculate the anisotropies of SBGW associated with the fluctuations in the number of cosmic string loops, considering both cosmic string cusps and kinks. We calculate the anisotropies as a ...

  4. Anisotropies in the gravitational-wave stochastic background

    International Nuclear Information System (INIS)

    We consider anisotropies in the stochastic background of gravitational-waves (SBGW) arising from random fluctuations in the number of gravitational-wave sources. We first develop the general formalism which can be applied to different cosmological or astrophysical scenarios. We then apply this formalism to calculate the anisotropies of SBGW associated with the fluctuations in the number of cosmic string loops, considering both cosmic string cusps and kinks. We calculate the anisotropies as a function of angle and frequency

  5. Influence of spin on fission fragments anisotropy

    Directory of Open Access Journals (Sweden)

    Ghodsi Omid N.

    2005-01-01

    Full Text Available An analysis of selected fission fragment angular distribution when at least one of the spins of the projectile or target is appreciable in induced fission was made by using the statistical scission model. The results of this model predicate that the spins of the projectile or target are affected on the nuclear level density of the compound nucleus. The experimental data was analyzed by means of the couple channel spin effect formalism. This formalism suggests that the projectile spin is more effective on angular anisotropies within the limits of energy near the fusion barrier.

  6. Shape anisotropy of polymers in disordered environment.

    Science.gov (United States)

    Blavatska, Viktoria; Janke, Wolfhard

    2010-11-14

    We study the influence of structural obstacles in a disordered environment on the size and shape characteristics of long flexible polymer macromolecules. We use the model of self-avoiding random walks on diluted regular lattices at the percolation threshold in space dimensions d=2 and d=3. Applying the pruned-enriched Rosenbluth method, we numerically estimate rotationally invariant universal quantities such as the averaged asphericity and prolateness of polymer chain configurations. Our results quantitatively reveal the extent of anisotropy of macromolecules due to the presence of structural defects. PMID:21073228

  7. Skyrmion Dynamics in Perpendicular Magnetic Anisotropy Nanostructures

    International Nuclear Information System (INIS)

    Full text: Topological solitons in perpendicular magnetic anisotropy (PMA) nanostructures have a rich excitation spectrum that is directly linked to their topological properties, as described by their Skyrmion number. They have been predicted to exhibit intriguing dynamics well as ultra-fast switching. We provide here direct imaging of dynamics of PMA topological solitons in CoB/Pt nanostructures with picosecond time resolution, using Scanning Transmission soft X-ray Microscopy. Specifically, we observe breathing-like and translational dynamical behaviour. We thereby establish a link between the dynamics of PMA solitons and their underlying topology, while also providing a much wider scope for dynamical experiments in magnetic elements. (author)

  8. Three-layer model for exchange anisotropy

    Science.gov (United States)

    Rezende, S. M.; Azevedo, A.; de Aguiar, F. M.; Fermin, J. R.; Egelhoff, W. F.; Parkin, S. S.

    2002-08-01

    Recent x-ray absorption measurements have indicated that the interface between the antiferromagnetic (AF) and the ferromagnetic (FM) layers in AF/FM bilayers instead of being abrupt, consists of a thin layer with uncompensated spins. Here the effect of an interfacial layer between the AF and FM layers on the ferromagnetic resonance response is investigated using a three-layer model for the exchange anisotropy. The calculated dependence of the resonance field with the azimuthal angle of the in-plane external field agrees quite well with experimental data in several samples, lending support to the existence of the uncompensated interfacial layer.

  9. Cosmology with cosmic microwave background anisotropy

    Indian Academy of Sciences (India)

    Tarun Sourdeep

    2006-10-01

    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 early Universe have also been established - `acausally' correlated initial perturbations in a flat, statistically isotropic Universe, adiabatic nature of primordial density perturbations. Direct evidence for gravitational instability mechanism for structure formation from primordial perturbations has been established. In the next decade, future experiments promise to strengthen these deductions and uncover the remaining crucial signature of inflation - the primordial gravitational wave background.

  10. Anisotropy in cohesive, frictional granular media

    International Nuclear Information System (INIS)

    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

  11. Molecular anisotropy effects in carbon K-edge scattering: depolarized diffuse scattering and optical anisotropy

    Energy Technology Data Exchange (ETDEWEB)

    Stone, Kevin H.

    2014-07-14

    Some polymer properties, such as conductivity, are very sensitive to short- and intermediate-range orientational and positional ordering of anisotropic molecular functional groups, and yet means to characterize orientational order in disordered systems are very limited. We demonstrate that resonant scattering at the carbon K-edge is uniquely sensitive to short-range orientation correlations in polymers through depolarized scattering at high momentum transfers, using atactic polystyrene as a well-characterized test system. Depolarized scattering is found to coexist with unpolarized fluorescence, and to exhibit pronounced anisotropy. We also quantify the spatially averaged optical anisotropy from low-angle reflectivity measurements, finding anisotropy consistent with prior visible, x-ray absorption, and theoretical studies. The average anisotropy is much smaller than that in the depolarized scattering and the two have different character. Both measurements exhibit clear spectral signatures from the phenyl rings and the polyethylene-like backbone. Discussion focuses on analysis considerations and prospects for using this depolarized scattering for studies of disorder in soft condensed matter.

  12. The study of the shape anisotropy in patterned permalloy films

    Institute of Scientific and Technical Information of China (English)

    Zhang Dong; Zhai Ya; Zhai Hong-Ru

    2007-01-01

    In this paper a systematic ferromagnetic resonance study shows that an in-plane magnetic anisotropy in the patterned micron octagon permalloy (Ni80Fe20) elements is mainly determined by the element geometry. The easy-axis is along the edge of the elements, and the hard-axis is along the diagonal. The shape anisotropy of the octagon elements is determined by square and equilateral octagon, and the theoretical calculation was studied on the shape anisotropy. The shape anisotropy of rectangular was calculated by using the same theory.

  13. Random and uniform anisotropy in soft magnetic nanocrystalline alloys (invited)

    Energy Technology Data Exchange (ETDEWEB)

    Flohrer, Sybille, E-mail: Sybille.Flohrer@vacuumschmelze.co [VACUUMSCHMELZE GmbH and Co. KG, Gruener Weg 37, D-63450 Hanau (Germany); Herzer, Giselher [VACUUMSCHMELZE GmbH and Co. KG, Gruener Weg 37, D-63450 Hanau (Germany)

    2010-05-15

    In amorphous and nanocrystalline transition metal based alloys with low magnetostriction, the soft magnetic properties are mainly determined by magneto-elastic and annealing-induced anisotropies which are uniform on a scale much larger than the exchange correlation length. Though, in the nanocrystalline case, there are situations where the random magneto-crystalline anisotropy of the grains becomes relevant. The present paper surveys the interplay between the random magneto-crystalline and the uniform field-induced anisotropy in nanocrystalline FeCuNbSiB soft magnets. Typical examples where the contribution of the random anisotropy becomes particularly visible in the magnetic domain structure will be reviewed.

  14. Computing magnetic anisotropy constants of single molecule magnets

    Indian Academy of Sciences (India)

    S Ramasesha; Shaon Sahoo; Rajamani Raghunathan; Diptiman Sen

    2009-09-01

    We present here a theoretical approach to compute the molecular magnetic anisotropy parameters, and for single molecule magnets in any given spin eigenstate of exchange spin Hamiltonian. We first describe a hybrid constant -valence bond (VB) technique of solving spin Hamiltonians employing full spatial and spin symmetry adaptation and we illustrate this technique by solving the exchange Hamiltonian of the Cu6Fe8 system. Treating the anisotropy Hamiltonian as perturbation, we compute the and values for various eigenstates of the exchange Hamiltonian. Since, the dipolar contribution to the magnetic anisotropy is negligibly small, we calculate the molecular anisotropy from the single-ion anisotropies of the metal centers. We have studied the variation of and by rotating the single-ion anisotropies in the case of Mn12Ac and Fe8 SMMs in ground and few low-lying excited states of the exchange Hamiltonian. In both the systems, we find that the molecular anisotropy changes drastically when the single-ion anisotropies are rotated. While in Mn12Ac SMM values depend strongly on the spin of the eigenstate, it is almost independent of the spin of the eigenstate in Fe8 SMM. We also find that the value is almost insensitive to the orientation of the anisotropy of the core Mn(IV) ions. The dependence of on the energy gap between the ground and the excited states in both the systems has also been studied by using different sets of exchange constants.

  15. Exonuclease III-assisted graphene oxide amplified fluorescence anisotropy strategy for ricin detection.

    Science.gov (United States)

    Xiao, Xue; Tao, Jing; Zhang, Hong Zhi; Huang, Cheng Zhi; Zhen, Shu Jun

    2016-11-15

    Graphene oxide (GO) is an excellent fluorescence anisotropy (FA) amplifier. However, in the conventional GO amplified FA strategy, one target can only induce the FA change of one fluorophore on probe, which limits the detection sensitivity. Herein, we developed an exonuclease III (Exo III) aided GO amplified FA strategy by using aptamer as an recognition element and ricin B-chain as a proof-of-concept target. The aptamer was hybridized with a blocker sequence and linked onto the surface of magnetic beads (MBs). Upon the addition of ricin B-chain, blocker was released from the surface of MBs and hybridized with the dye-modified probe DNA on the surface of GO through the toehold-mediated strand exchange reaction. The formed blocker-probe DNA duplex triggered the Exo III-assisted cyclic signal amplification by repeating the hybridization and digestion of probe DNA, liberating the fluorophore with several nucleotides (low FA value). Thus, ricin B-chain could be sensitively detected by the significantly decreased FA. The linear range was from 1.0μg/mL to 13.3μg/mL and the limit of detection (LOD) was 400ng/mL. This method improved the sensitivity of FA assay and it could be generalized to any kind of target detection based on the use of an appropriate aptamer. PMID:27295569

  16. Traversing probe system

    International Nuclear Information System (INIS)

    This invention comprises a rotatable annular probe-positioner which carries at least one radially disposed sensing probe, such as a Pitot tube having a right-angled tip. The positioner can be coaxially and rotatably mounted within a compressor casing or the like and then actuated to orient the sensing probe as required to make measurements at selected stations in the annulus between the positioner and compressor casing. The positioner can be actuated to (a) selectively move the probe along its own axis, (b) adjust the yaw angle of the right-angled probe tip, and (c) revolve the probe about the axis common to the positioner and casing. A cam plate engages a cam-follower portion of the probe and normally rotates with the positioner. The positioner includes a first-motor-driven ring gear which effects slidable movement of the probe by rotating the positioner at a time when an external pneumatic cylinder is actuated to engage the cam plate and hold it stationary. When the pneumatic cylinder is not actuated, this ring gear can be driven to revolve the positioner and thus the probe to a desired circumferential location about the above-mentioned common axis. A second motor-driven ring gear included in the positioner can be driven to rotate the probe about its axis, thus adjusting the yaw angle of the probe tip. The positioner can be used in highly corrosive atmosphere, such as gaseous uranium hexafluoride. 10 claims, 6 figures

  17. The Anisotropy of Replicated Aluminum Foams

    Directory of Open Access Journals (Sweden)

    Eugeny L. Furman

    2014-01-01

    Full Text Available The replication casting process gives the open-cell aluminum foams that can be used in many industrial applications as well as in filtering technology. The essential requirement for filters is the uniformity of filtering degree which is defined by the minimal pore size. However the structure of replication castings is often inhomogeneous and the minimal pore radius is decreasing in the direction of melt infiltration. The objective of this investigation is to study the dynamics of melt impregnation of the porous medium by vacuum suction to identify the possibility of reducing the anisotropy. Theoretical data illustrate the processes at the boundary between melt and gas medium. The experiments were carried out using the replication aluminum samples produced according to commercial technology. It was found that the permeability coefficient varies throughout the height of castings. A method for estimation of pressure on the line of melt movement was proposed. The resistance of NaCl layer and circular vents of the mold causes the inhomogeneity of castings. Finally the ways of minimizing the anisotropy were offered.

  18. Texture and anisotropy analysis of Qusaiba shales

    KAUST Repository

    Kanitpanyacharoen, Waruntorn

    2011-02-17

    Scanning and transmission electron microscopy, synchrotron X-ray diffraction, microtomography and ultrasonic velocity measurements were used to characterize microstructures and anisotropy of three deeply buried Qusaiba shales from the Rub\\'al-Khali basin, Saudi Arabia. Kaolinite, illite-smectite, illite-mica and chlorite show strong preferred orientation with (001) pole figure maxima perpendicular to the bedding plane ranging from 2.4-6.8 multiples of a random distribution (m.r.d.). Quartz, feldspars and pyrite crystals have a random orientation distribution. Elastic properties of the polyphase aggregate are calculated by averaging the single crystal elastic properties over the orientation distribution, assuming a nonporous material. The average calculated bulk P-wave velocities are 6.2 km/s (maximum) and 5.5 km/s (minimum), resulting in a P-wave anisotropy of 12%. The calculated velocities are compared with those determined from ultrasonic velocity measurements on a similar sample. In the ultrasonic experiment, which measures the effects of the shale matrix as well as the effects of porosity, velocities are smaller (P-wave maximum 5.3 km/s and minimum 4.1 km/s). The difference between calculated and measured velocities is attributed to the effects of anisotropic pore structure and to microfractures present in the sample, which have not been taken into account in the matrix averaging. © 2011 European Association of Geoscientists & Engineers.

  19. Cosmic microwave anisotropies from BPS semilocal strings

    CERN Document Server

    Urrestilla, Jon; Hindmarsh, Mark; Kunz, Martin; Liddle, Andrew R

    2007-01-01

    We present the first ever calculation of cosmic microwave background CMB anisotropy power spectra from semilocal cosmic strings, obtained via simulations of a classical field theory. Semilocal strings are a type of non-topological defect arising in some models of inflation motivated by fundamental physics, and are thought to relax the constraints on the symmetry breaking scale as compared to models with (topological) cosmic strings. We derive constraints on the model parameters, including the string tension parameter mu, from fits to cosmological data, and find that in this regard BPS semilocal strings resemble textures more than topological strings. The observed microwave anisotropy at l=10 is reproduced if Gmu = 4.9x10^{-6} (G is Newton's constant). However as with other defects the spectral shape does not match observations, and in models with inflationary perturbations plus semilocal strings the 95% confidence level upper bound is Gmu<1.9x10^{-6} when CMB data, Hubble Key Project and Big Bang Nucleosyn...

  20. α-Zr self-diffusion anisotropy

    International Nuclear Information System (INIS)

    Self-diffusion coefficients (D) have been measured in nominally pure (NP) α-Zr single crystals (∼ 50 ppma Fe) in the range 867-1107 K, in directions either parallel (Dpa) or perpendicular (Dpe) to the c-axis. Measurements were also made on high-purity (HP) α-Zr single crystals (95Zr) counting. Sectioning was done with a sputtering device, or a microtome (some NP experiments at 1107 K). D values for NP Zr are about an order of magnitude higher than the corresponding values for HP Zr. Diffusion anisotropy is complicated. The sputter-sectioned NP Zr specimens show increasing anisotropy ratios (AR = Dpa/Dpe), from 1.0 to 3.2, with decreasing temperatures, whereas AR = 0.53 for both the microtome-sectioned NP and sputter-sectioned HP Zr: the low AR value is consistent with expectations based on intrinsic self-diffusion in hcp metals with c/a < 1.633. (author). 12 refs., 1 tab., 3 figs

  1. Electromagnetic Instabilities Excited by Electron Temperature Anisotropy

    Institute of Scientific and Technical Information of China (English)

    陆全明; 王连启; 周艳; 王水

    2004-01-01

    One-dimensional particle-in-cell simulations are performed to investigate the nonlinear evolution of electromagnetic instabilities excited by the electron temperature anisotropy in homogeneous plasmas with different parameters. The results show that the electron temperature anisotropy can excite the two right-hand electromagnetic instabilities, one has the frequency higher than Ωe, the other is the whistler instability with larger amplitude,and its frequency is below Ωe. Their dispersion relations are consistent with the prediction from the cold plasma theory. In the initial growth stage (prediction from linear theory), the frequency of the dominant mode (the mode whose amplitude is large enough) of the whistler wave almost does not change, but in the saturation stage the situation is different. In the case that the ratio of electron plasma frequency to cyclotron frequency is larger than 1, the frequency of the dominant mode of the whistler wave drifts from high to low continuously. However, for the case of the ratio smaller than 1, besides the original dominant mode of the whistler wave whose frequency is about 2.6ωe, another dominant mode whose frequency is about 1.55ωe also begins to be excited at definite time,and its amplitude increases with time until it exceeds the original dominant mode.

  2. Scanning anisotropy parameters in complex media

    KAUST Repository

    Alkhalifah, Tariq Ali

    2011-03-21

    Parameter estimation in an inhomogeneous anisotropic medium offers many challenges; chief among them is the trade-off between inhomogeneity and anisotropy. It is especially hard to estimate the anisotropy anellipticity parameter η in complex media. Using perturbation theory and Taylor’s series, I have expanded the solutions of the anisotropic eikonal equation for transversely isotropic (TI) media with a vertical symmetry axis (VTI) in terms of the independent parameter η from a generally inhomogeneous elliptically anisotropic medium background. This new VTI traveltime solution is based on a set of precomputed perturbations extracted from solving linear partial differential equations. The traveltimes obtained from these equations serve as the coefficients of a Taylor-type expansion of the total traveltime in terms of η. Shanks transform is used to predict the transient behavior of the expansion and improve its accuracy using fewer terms. A homogeneous medium simplification of the expansion provides classical nonhyperbolic moveout descriptions of the traveltime that are more accurate than other recently derived approximations. In addition, this formulation provides a tool to scan for anisotropic parameters in a generally inhomogeneous medium background. A Marmousi test demonstrates the accuracy of this approximation. For a tilted axis of symmetry, the equations are still applicable with a slightly more complicated framework because the vertical velocity and δ are not readily available from the data.

  3. Determination of the magnetic anisotropy constant of Cu/Fe/SiO2/Si by a magneto-optical Kerr effect susceptometer

    International Nuclear Information System (INIS)

    The magneto-optical Kerr effect susceptometry technique is proposed to determine the uniaxial magnetic anisotropy (UMA) constant Ku. The magnetic properties of Cu/Fe/SiO2/Si grown by dc magnetron sputtering were investigated. The in-plane uniaxial magnetic anisotropy was probed by the magneto-optical Kerr effect (MOKE). The value of UMA, Ku = 2.5 ×103 J/m3, was simulated from the field dependence of ac susceptibility along the hard axis according to the Stoner—Wohlfarth (S—W) model, which is consistent with Ku = 2.7 × 103 J/m3 calculated from the magnetic hysteresis loops. Our results show that the magneto-optical Kerr effect susceptometry can be employed to determine the magnetic anisotropy constant owing to its high sensitivity. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  4. Measurements of cosmic ray anisotropies from Pioneers 10 and 11

    International Nuclear Information System (INIS)

    Cosmic ray anisotropy measurements are performed by the University of California, San Diego experiments on Pioneers 10 and 11. A directional Cerenkov counter sensitive to protons and α particles with kinetic energies >= 480 MeV/nucleon is used to determine east-west and north-south anisotropies. (orig./WBU)

  5. Probing primordial features with future galaxy surveys

    CERN Document Server

    Ballardini, Mario; Fedeli, Cosimo; Moscardini, Lauro

    2016-01-01

    We study the capability of future measurements of the galaxy clustering power spectrum to probe departures from a power-law spectrum for primordial fluctuations. On considering the information from the galaxy clustering power spectrum up to quasi-linear scales, i.e. $k<0.1$ h Mpc$^{-1}$, we present forecasts for DESI, Euclid and SPHEREx in combination with CMB measurements. As examples of departures in the primordial power spectrum from a simple power-law, we consider four $Planck$ 2015 best-fits motivated by inflationary models with different breaking of the slow-roll approximation. These four representative models provide an improved fit to CMB temperature anisotropies, although not at statistical significant level. As for other extensions in the matter content of the simplest $\\Lambda$CDM model, the complementarity of the information in the resulting matter power spectrum expected from these galaxy surveys and in the primordial power spectrum from CMB anisotropies can be effective in constraining cosmol...

  6. An approach to directly probe simultaneity

    CERN Document Server

    Kipreos, Edward T

    2016-01-01

    The theory of special relativity derives from the Lorentz transformation. The Lorentz transformation implies differential simultaneity and light speed isotropy. Experiments to probe differential simultaneity should be able to distinguish the Lorentz transformation from a kinematically-similar alternate transformation that predicts absolute simultaneity, the absolute Lorentz transformation. Here, we describe how published optical tests of light speed isotropy/anisotropy cannot distinguish between the two transformations. We show that the shared equations of the two transformations, from the perspective of the "stationary" observer, are sufficient to predict null results in optical resonator experiments and in tests of frequency changes in one-way light paths. In an influential 1910 exposition on differential simultaneity, Comstock described how a "stationary" observer would observe different clock readings for spatially-separated "moving" clocks. The difference in clock readings is an integral aspect of differ...

  7. Probing SZ Source Detection with Gasdynamical Simulations

    CERN Document Server

    Bond, J R; Wadsley, J W; Gladders, M D; Ruetalo, Marcelo I.; Wadsley, James W.; Gladders, Michael D.

    2001-01-01

    The huge worldwide investment in CMB experiments should make the Sunyaev-Zeldovich (SZ) effect a key probe of the cosmic web in the near future. For the promise to be realized, substantial development of simulation and analysis tools to relate observation to theory is needed. The high nonlinearity and dissipative/feedback gas physics lead to highly non-Gaussian patterns that are much more difficult to analyze than Gaussian primary anisotropies for which the procedures are reasonably well developed. Historical forecasts for what CMB experiments might see used semi-analytic tools, including large scale map constructions, with localized and simplified pressure structures distributed on a point process of (clustered) sources. Hydro studies beyond individual cluster/supercluster systems were inadequate, but now large-volume simulations with high resolution are beginning to shift the balance. We illustrate this by applying ``Gasoline'' (parallelized Tree+SPH) computations to construct SZ maps and derive statistical...

  8. Magnetisation reversal in anisotropy graded Co/Pd multilayers

    International Nuclear Information System (INIS)

    We demonstrate high precision controllability of the magnetization reversal nucleation process in [Co/Pd]8 multilayer films consisting of two sets of bilayers with high and low perpendicular anisotropy, respectively. The anisotropy of the entire film is set by the degree of Co/Pd interfacial mixing during deposition which provides fine control of the anisotropy of an individual bilayer in the multilayer stack. The relative number of each type of bilayer is used to select the magnetisation reversal behavior such that changing one bilayer changes the properties of the entire multilayer through anisotropy averaging. A simple extension to the sputtering protocol would provide multilayer films with fully graded anisotropy, while maintaining a constant saturation magnetization opening new possibilities for the creation of highly engineered multilayer structures for spin torque devices and future magnetic recording media

  9. Structural anisotropy in amorphous Fe-Tb thin films

    International Nuclear Information System (INIS)

    We have used conventional and anomalous dispersion x-ray scattering to study the near-neighbor atomic environments in sputter-deposited amorphous Fe-Tb thin films with a large perpendicular magnetic anisotropy. The as-deposited films show a clear structural anisotropy, with more Fe-Tb near neighbor pairs in the out-of-plane direction. Upon annealing, the magnetic anisotropy drops significantly, and we see a corresponding reduction in the structural anisotropy. The number of Fe-Tb near-neighbors increases in the in-plane direction, but does not change in the out-of-plane direction. Therefore, the distribution of Fe-Tb near neighbors becomes more uniform upon annealing. We conclude that the observed reduction in perpendicular magnetic anisotropy energy is a result of this change in structure. copyright 1996 The American Physical Society

  10. Discriminating neurogenic from myopathic disease via measurement of muscle anisotropy.

    Science.gov (United States)

    Garmirian, Lindsay P; Chin, Anne B; Rutkove, Seward B

    2009-01-01

    Skeletal muscle is electrically anisotropic, with a tendency for applied electrical current to flow more readily along muscle fibers than across them. In this study, we assessed a method for non-invasive measurement of anisotropy to determine its potential to serve as a new technique for distinguishing neurogenic from myopathic disease. Measurements were made on the biceps brachii and tibialis anterior muscles in 15 normal subjects and 12 patients with neuromuscular disease (6 with amyotrophic lateral sclerosis and 6 with various myopathies) using 50 kHZ applied current. Consistent multi-angle anisotropic patterns were found for reactance and phase in both muscles in normal subjects. Normalized anisotropy differences for each subject were defined, and group average values identified. The amyotrophic lateral sclerosis (ALS) patients demonstrated increased and distorted anisotropy patterns, whereas myopathic patients demonstrated normal or reduced anisotropy. These results suggest that non-invasive measurement of muscle anisotropy has potential for diagnosis of neuromuscular diseases. PMID:19058193

  11. Tuning the Magnetic Anisotropy at a Molecule-Metal Interface

    DEFF Research Database (Denmark)

    Bairagi, K.; Bellec, A.; Repain, V.; Chacon, C.; Girard, Y.; Garreau, Y.; Lagoute, J.; Rousset, S.; Breitwieser, R.; Hu, Yu-Cheng; Chao, Yen Cheng; Pai, Woei Wu; Li, D.; Smogunov, A.; Barreteau, Cyrille

    2015-01-01

    We demonstrate that a C60 overlayer enhances the perpendicular magnetic anisotropy of a Co thin film, inducing an inverse spin reorientation transition from in plane to out of plane. The driving force is the C60/Co interfacial magnetic anisotropy that we have measured quantitatively in situ as a...... function of the C60 coverage. Comparison with state-of-the-art ab initio calculations show that this interfacial anisotropy mainly arises from the local hybridization between C60 pz and Co dz2 orbitals. By generalizing these arguments, we also demonstrate that the hybridization of C60 with a Fe(110......) surface decreases the perpendicular magnetic anisotropy. These results open the way to tailor the interfacial magnetic anisotropy in organic-material-ferromagnet systems....

  12. Carrier-dependent magnetic anisotropy of Gd-adsorbed graphene

    Directory of Open Access Journals (Sweden)

    Yuan Lu

    2016-05-01

    Full Text Available Using first-principles calculation based on density functional theory, we study the magnetic anisotropy of Gd-adsorbed graphene and its dependence on carrier accumulation. We show that carrier accumulation not only impacts the magnitude of magnetic anisotropy but also switches its sign. Hole accumulation enhances the perpendicular anisotropy up to ∼16 meV per Gd atom, while electron accumulation switches the anisotropy from perpendicular to in-plane direction. Moreover, we find that the first order perturbation of spin-orbit coupling interaction induces a pseudo-gap at Γ for the perpendicular magnetization, which leads to the the anomalous magnetic anisotropy for the neutral composite. Our findings pave the way for magneto-electric materials based on rare-earth-decorated graphene for voltage-controlled spintronics.

  13. Intrinsic anisotropy-defined magnetization reversal in submicron ring magnets

    Science.gov (United States)

    Li, S. P.; Lew, W. S.; Bland, J. A. C.; Natali, M.; Lebib, A.; Chen, Y.

    2002-12-01

    We report a study of the effect of magnetocrystalline anisotropy in the magnetization reversal of submicron Co rings fabricated by nanoimprint lithography. For weak magnetocrystalline anisotropy, the complete reversal takes place via a transition from saturation at large negative fields, into a vortex configuration at small fields, and back to reverse saturation at large positive fields. When the anisotropy strength is increased to a critical value, the intermediate vortex configuration no longer exists in the magnetization reversal along the easy axis; instead, the reversal occurs through a rapid jump. However, when the applied field direction is far from the easy axis, the presence of the magnetocrystalline anisotropy favors local vortex nucleation, and this leads to a similar switching process as found for low anisotropy. Micromagnetic simulations indicate that the magnetization reversal process of the rings, starts from a buckling-like reverse domain nucleation, followed by local vortex formation and an avalanche process of local vortex nucleation.

  14. Polarization and dilepton anisotropy in pion-nucleon collisions

    CERN Document Server

    Speranza, Enrico; Friman, Bengt

    2016-01-01

    Hadronic polarization and the related anisotropy of the dilepton angular distribution are studied for the reaction $\\pi N \\rightarrow Ne^+ e^-$. We employ consistent effective interactions for baryon resonances up to spin-5/2, where non-physical degrees of freedom are eliminated, to compute the anisotropy coefficients for isolated intermediate baryon resonances. It is shown that the spin and parity of the intermediate baryon resonance is reflected in the angular dependence of the anisotropy coefficient. We then compute the anisotropy coefficient including the $N(1520)$ and $N(1440)$ resonances, which are essential at the collision energy of the recent data obtained by the HADES collaboration on this reaction. We conclude that the anisotropy coefficient provides useful constraints for unravelling the resonance contributions to this process.

  15. Carrier-dependent magnetic anisotropy of Gd-adsorbed graphene

    Science.gov (United States)

    Lu, Yuan; Zhou, Tie-ge; Shao, Bin; Zuo, Xu; Feng, Min

    2016-05-01

    Using first-principles calculation based on density functional theory, we study the magnetic anisotropy of Gd-adsorbed graphene and its dependence on carrier accumulation. We show that carrier accumulation not only impacts the magnitude of magnetic anisotropy but also switches its sign. Hole accumulation enhances the perpendicular anisotropy up to ˜16 meV per Gd atom, while electron accumulation switches the anisotropy from perpendicular to in-plane direction. Moreover, we find that the first order perturbation of spin-orbit coupling interaction induces a pseudo-gap at Γ for the perpendicular magnetization, which leads to the the anomalous magnetic anisotropy for the neutral composite. Our findings pave the way for magneto-electric materials based on rare-earth-decorated graphene for voltage-controlled spintronics.

  16. Fine structure constant variation or spacetime anisotropy?

    International Nuclear Information System (INIS)

    Recent observations on the quasar absorption spectra supply evidence for the variation of the fine structure constant α. In this paper, we propose another interpretation of the observational data on the quasar absorption spectra: a scenario with spacetime inhomogeneity and anisotropy. Maybe the spacetime is characterized by the Finsler geometry instead of the Riemann one. The Finsler geometry admits fewer symmetries than the Riemann geometry does. We investigate the Finslerian geodesic equations in the Randers spacetime (a special Finsler spacetime). It is found that the cosmological redshift in this spacetime deviates from the one in general relativity. The modification term to the redshift could be generally revealed as a monopole plus dipole function of spacetime locations and directions. We suggest that this modification corresponds to the spatial monopole and dipole of α variation in the quasar absorption spectra. (orig.)

  17. CMB Anisotropies from a Gradient Mode

    CERN Document Server

    Mirbabayi, Mehrdad

    2014-01-01

    A pure gradient mode must have no observable dynamical effect at linear level. We confirm this by showing that its contribution to the dipolar power asymmetry of CMB anisotropies vanishes, if Maldacena's consistency condition is satisfied. To this end, the existing second order Sachs-Wolfe formula in the squeezed limit is extended to include a gradient in the long mode and to account for the change in the location of the last scattering surface induced by this mode. At second order, a gradient mode generated in Single-field inflation is shown to induce a quadrupole moment. For instance in a matter-dominated model it is equal to 5/18 times the square of the linear gradient part. This quadrupole can be cancelled by superposing a quadratic perturbation. The result is shown to be a non-linear extension of Weinberg's adiabatic modes: a long-wavelength physical mode which looks locally like a coordinate transformation.

  18. Creep anisotropy of Zircaloy cladding tubes

    International Nuclear Information System (INIS)

    First of all, a survey is given on the texture of Zircaloy cladding tubes obtained depending on the manufacturing conditions, and the state of knowledge on the anisotropy of the mechanical properties of the zirconium alloys connected with the texture is outlined. Theoretical formulations are set up for the phenomenological representation of the anisotropic creep. The results of tension and compression tests and the thus obtained creep site curves exhibit distinct differences with tubes having different textures. Furthermore, on asymmetry regarding compressive tensile stress is found in such a manner that the material under compression stress is more resistant to creep. Finally, discussions follow on the deformation mechanisms and a comparison with flow processes as well as indications on the significance of these creep results within the framework of fuel rod design are given. (IHoe/LH)

  19. Orientational anisotropy and interfacial transport in polycrystals

    Science.gov (United States)

    Moghadam, M. M.; Rickman, J. M.; Harmer, M. P.; Chan, H. M.

    2016-04-01

    Interfacial diffusion is governed to a large degree by geometric parameters that are determined by crystallographic orientation. In this study, we assess the impact of orientational anisotropy on mass transport at internal interfaces, focusing on the role of preferred crystallographic orientation (i.e., texture) on mass diffusion in a polycrystal. More specifically, we perform both numerical and analytical studies of steady-state diffusion for polycrystals having various grain-orientation distributions. By relating grain misorientation to grain-boundary energies and, via the Borisov relation, to the diffusivity, we link microstructure variability to kinetics. Our aim is to correlate shape features of the orientation distribution, such as the location and shapes of peaks, with the calculated effective diffusivity. Finally, we discuss the role of crystallographic constraints, such as those associated with grain junctions, in determining the effective diffusivity of a polycrystal.

  20. Perpendicular anisotropy in Fe/Ag multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Fetzer, C.; Szucs, I.S.; Dezsi, I. [KFKI Research Institute for Particle and Nuclear Physics, Budapest (Hungary); Kaptas, D.; Kiss, L.F.; Vincze, I. [Research Institute for Solid State Physics and Optics, Budapest (Hungary); Balogh, J.

    2008-08-15

    The direction of the spontaneous magnetization changes from out of plane to in plane at around x=0.6 in[Ag(2.6 nm)/Fe(x nm)]{sub 10} multilayers (0.2{<=}x{<=}1) prepared on Si(111) substrate by vacuum evaporation. Transmission Moessbauer spectroscopy measurements of removed samples with a thick capping layer are compared to conversion electron Moessbauer spectroscopy measurements of samples on the Si substrate with a thin capping layer. The stress arising because of the application of a thick capping layer and the removal of the samples from the substrate is shown to have negligible effect on the spontaneous magnetization. The results support that the appearance of the perpendicular anisotropy below x=0.6 is an intrinsic property of Fe/Ag multilayers. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  1. Nanopatterning reconfigurable magnetic landscapes via thermally assisted scanning probe lithography

    Science.gov (United States)

    Albisetti, E.; Petti, D.; Pancaldi, M.; Madami, M.; Tacchi, S.; Curtis, J.; King, W. P.; Papp, A.; Csaba, G.; Porod, W.; Vavassori, P.; Riedo, E.; Bertacco, R.

    2016-06-01

    The search for novel tools to control magnetism at the nanoscale is crucial for the development of new paradigms in optics, electronics and spintronics. So far, the fabrication of magnetic nanostructures has been achieved mainly through irreversible structural or chemical modifications. Here, we propose a new concept for creating reconfigurable magnetic nanopatterns by crafting, at the nanoscale, the magnetic anisotropy landscape of a ferromagnetic layer exchange-coupled to an antiferromagnetic layer. By performing localized field cooling with the hot tip of a scanning probe microscope, magnetic structures, with arbitrarily oriented magnetization and tunable unidirectional anisotropy, are reversibly patterned without modifying the film chemistry and topography. This opens unforeseen possibilities for the development of novel metamaterials with finely tuned magnetic properties, such as reconfigurable magneto-plasmonic and magnonic crystals. In this context, we experimentally demonstrate spatially controlled spin wave excitation and propagation in magnetic structures patterned with the proposed method.

  2. Seven-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Galactic Foreground Emission

    CERN Document Server

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

    2010-01-01

    [Abridged] We present updated estimates of Galactic foreground emission using seven years of WMAP data. Using the power spectrum of differences between multi-frequency template-cleaned maps, we find no evidence for foreground contamination outside of the updated (KQ85y7) foreground mask. We place a 15 microKelvin upper bound on rms foreground contamination in the cleaned maps used for cosmological analysis. We find no indication in the polarization data of an extra "haze" of hard synchrotron emission from energetic electrons near the Galactic center. We provide an updated map of the cosmic microwave background (CMB) using the internal linear combination (ILC) method, updated foreground masks, and updates to point source catalogs with 62 newly detected sources. Also new are tests of the Markov chain Monte Carlo (MCMC) foreground fitting procedure against systematics in the time-stream data, and tests against the observed beam asymmetry. Within a few degrees of the Galactic plane, WMAP total intensity data show...

  3. Seven-year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Interpretation

    OpenAIRE

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

    2011-01-01

    (Abridged) The 7-year WMAP data and improved astrophysical data rigorously test the standard cosmological model and its extensions. By combining WMAP with the latest distance measurements from BAO and H0 measurement, we determine the parameters of the simplest LCDM model. The power-law index of the primordial power spectrum is n_s=0.968+-0.012, a measurement that excludes the scale-invariant spectrum by 99.5%CL. The other parameters are also improved from the 5-year results. Notable examples ...

  4. Star Formation in Massive Clusters via the Wilkinson Microwave Anisotropy Probe and the Spitzer Glimpse Survey

    CERN Document Server

    Murray, N W

    2009-01-01

    We use the WMAP maximum entropy method foreground emission map combined with previously determined distances to giant HII regions to measure the free-free flux at Earth and the free-free luminosity of the galaxy. We find a total flux f_\

  5. SEVEN-YEAR WILKINSON MICROWAVE ANISOTROPY PROBE (WMAP ) OBSERVATIONS: GALACTIC FOREGROUND EMISSION

    International Nuclear Information System (INIS)

    We present updated estimates of Galactic foreground emission using seven years of WMAP data. Using the power spectrum of differences between multi-frequency template-cleaned maps, we find no evidence for foreground contamination outside of the updated (KQ85y7) foreground mask. We place a 15 μK upper bound on rms foreground contamination in the cleaned maps used for cosmological analysis. Further, the cleaning process requires only three power-law foregrounds outside of the mask. We find no evidence for polarized foregrounds beyond those from soft (steep-spectrum) synchrotron and thermal dust emission; in particular we find no indication in the polarization data of an extra 'haze' of hard synchrotron emission from energetic electrons near the Galactic center. We provide an updated map of the cosmic microwave background (CMB) using the internal linear combination method, updated foreground masks, and updates to point source catalogs using two different techniques. With additional years of data, we now detect 471 point sources using a five-band technique and 417 sources using a three-band CMB-free technique. In total there are 62 newly detected point sources, a 12% increase over the five-year release. Also new are tests of the Markov chain Monte Carlo foreground fitting procedure against systematics in the time-stream data, and tests against the observed beam asymmetry. Within a few degrees of the Galactic plane, the behavior in total intensity of low-frequency foregrounds is complicated and not completely understood. WMAP data show a rapidly steepening spectrum from 20 to 40 GHz, which may be due to emission from spinning dust grains, steepening synchrotron, or other effects. Comparisons are made to a 1 deg 408 MHz map (Haslam et al.) and the 11 deg ARCADE 2 data (Singal et al.). We find that spinning dust or steepening synchrotron models fit the combination of WMAP and 408 MHz data equally well. ARCADE data appear inconsistent with the steepening synchrotron model and consistent with the spinning dust model, though some discrepancies remain regarding the relative strength of spinning dust emission. More high-resolution data in the 10-40 GHz range would shed much light on these issues.

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

    International Nuclear Information System (INIS)

    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 (H0) measurement, we determine the parameters of the simplest six-parameter ΛCDM model. The power-law index of the primordial power spectrum is ns = 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, ΣMν eff = 4.34+0.86-0.88 (68% CL), which benefit from better determinations of the third peak and H0. The limit on a constant dark energy equation of state parameter from WMAP+BAO+H0, 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 Yp = 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.o1 ± 1.o4(statistical) ± 1.o5(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.

  7. SEVEN-YEAR WILKINSON MICROWAVE ANISOTROPY PROBE (WMAP ) OBSERVATIONS: PLANETS AND CELESTIAL CALIBRATION SOURCES

    International Nuclear Information System (INIS)

    We present WMAP seven-year observations of bright sources which are often used as calibrators at microwave frequencies. Ten objects are studied in five frequency bands (23-94 GHz): the outer planets (Mars, Jupiter, Saturn, Uranus, and Neptune) and five fixed celestial sources (Cas A, Tau A, Cyg A, 3C274, and 3C58). The seven-year analysis of Jupiter provides temperatures which are within 1σ of the previously published WMAP five-year values, with slightly tighter constraints on variability with orbital phase (0.2% ± 0.4%), and limits (but no detections) on linear polarization. Observed temperatures for both Mars and Saturn vary significantly with viewing geometry. Scaling factors are provided which, when multiplied by the Wright Mars thermal model predictions at 350 μm, reproduce WMAP seasonally averaged observations of Mars within ∼2%. An empirical model is described which fits brightness variations of Saturn due to geometrical effects and can be used to predict the WMAP observations to within 3%. Seven-year mean temperatures for Uranus and Neptune are also tabulated. Uncertainties in Uranus temperatures are 3%-4% in the 41, 61, and 94 GHz bands; the smallest uncertainty for Neptune is 8% for the 94 GHz band. Intriguingly, the spectrum of Uranus appears to show a dip at ∼30 GHz of unidentified origin, although the feature is not of high statistical significance. Flux densities for the five selected fixed celestial sources are derived from the seven-year WMAP sky maps and are tabulated for Stokes I, Q, and U, along with polarization fraction and position angle. Fractional uncertainties for the Stokes I fluxes are typically 1% to 3%. Source variability over the seven-year baseline is also estimated. Significant secular decrease is seen for Cas A and Tau A: our results are consistent with a frequency-independent decrease of about 0.53% per year for Cas A and 0.22% per year for Tau A. We present WMAP polarization data with uncertainties of a few percent for Tau A. Where appropriate, WMAP results are compared against previous findings in the literature. With an absolute calibration uncertainty of 0.2%, WMAP data are a valuable asset for calibration work.

  8. First Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations Determination of Cosmological Parameters

    CERN Document Server

    Spergel, D N; Peiris, H V; Komatsu, E; Nolta, M R; Bennett, C L; Halpern, M; Hinshaw, G; Jarosik, N C; Kogut, A J; Limon, M; Meyer, S S; Page, L; Tucker, G S; Weiland, J L; Wollack, E; Wright, E L

    2003-01-01

    WMAP precision data enables accurate testingof cosmological models. We find that the emerging standard model of cosmology, a flat Lambda-dominated universe seeded by a nearly scale-invariant adiabatic Gaussian fluctuations, fits the WMAP data. With parameters fixed only by WMAP data, we can fit finer scale CMB measurements and measurements of large scale structure (galaxy surveys and the Lyman Alpha forest). This simple model is also consistent with a host of other astronomical measurements. We then fit the model parameters to a combination of WMAP data with other finer scale CMB experiments (ACBAR and CBI), 2dFGRS measurements and Lyman Alpha forest data to find the model's best fit cosmological parameters: h = 0.71^{+ 0.04}_{- 0.03}}, Omega_bh^2 = 0.0224+/-0.0009}, Omega_mh^2 = 0.135^{+ 0.008}_{- 0.009}}, tau = 0.17+/-0.06}, n_s(0.05 Mpc$^{-1}) = 0.93 \\pm 0.03}, and sigma_8 = 0.84+/-0.04}. WMAP's best determination of tau=0.17+/-0.04 arises directly from the TE data and not from this model fit, but they are...

  9. Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Likelihoods and Parameters from the WMAP data

    CERN Document Server

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

    2008-01-01

    This paper focuses on cosmological constraints derived from analysis of WMAP data alone. A simple LCDM cosmological model fits the five-year WMAP temperature and polarization data. The basic parameters of the model are consistent with the three-year data and now better constrained: Omega_b h^2 = 0.02273+-0.00062, Omega_c h^2 = 0.1099+-0.0062, Omega_L = 0.742+-0.030, n_s = 0.963+0.014- 0.015, tau = 0.087+-0.017, sigma_8 = 0.796+-0.036. With five years of polarization data, we have measured the optical depth to reionization, tau>0, at 5 sigma significance. The redshift of an instantaneous reionization is constrained to be z_reion = 11.0+-1.4 with 68% confidence. This excludes a sudden reionization of the universe at z=6 at more than 3.5 sigma significance, suggesting that reionization was an extended process. Using two different methods for polarized foreground cleaning, and foreground marginalization, we get consistent estimates for the optical depth. This cosmological model also fits small-scale CMB data, and...

  10. The COBE cosmic 3 K anisotropy experiment: A gravity wave and cosmic string probe

    Science.gov (United States)

    Bennett, Charles L.; Smoot, George F.

    1989-01-01

    Among the experiments to be carried into orbit next year, by the COBE satellite, are differential microwave radiometers. They will make sensitive all-sky maps of the temperature of the cosmic microwave background radiation at three frequencies, giving dipole, quadrupole, and higher order multipole measurements of the background radiation. The experiment will either detect, or place significant constraints on, the existence of cosmic strings and long wavelength gravity waves.

  11. Seven-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Planets and Celestial Calibration Sources

    CERN Document Server

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

    2010-01-01

    We present WMAP seven-year observations of bright sources which are often used as calibrators at microwave frequencies. Ten objects are studied in five frequency bands (23 - 94 GHz): the outer planets (Mars, Jupiter, Saturn, Uranus and Neptune) and five fixed celestial sources (Cas A, Tau A, Cyg A, 3C274 and 3C58). The seven-year analysis of Jupiter provides temperatures which are within 1-sigma of the previously published WMAP five-year values, with slightly tighter constraints on variability with orbital phase, and limits (but no detections) on linear polarization. Scaling factors are provided which, when multiplied by the Wright Mars thermal model predictions at 350 micron, reproduce WMAP seasonally averaged observations of Mars within ~2%. An empirical model is described which fits brightness variations of Saturn due to geometrical effects and can be used to predict the WMAP observations to within 3%. Seven-year mean temperatures for Uranus and Neptune are also tabulated. Uncertainties in Uranus temperatu...

  12. 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

  13. Large anisotropy of electron and hole g factors in infrared-emitting InAs/InAlGaAs self-assembled quantum dots

    Science.gov (United States)

    Belykh, V. V.; Yakovlev, D. R.; Schindler, J. J.; Zhukov, E. A.; Semina, M. A.; Yacob, M.; Reithmaier, J. P.; Benyoucef, M.; Bayer, M.

    2016-03-01

    A detailed study of the g -factor anisotropy of electrons and holes in InAs/In0.53Al0.24Ga0.23As self-assembled quantum dots emitting in the telecom spectral range of 1.5 -1.6 μ m (around 0.8 eV photon energy) is performed by time-resolved pump-probe ellipticity technique using a superconducting vector magnet. All components of the g -factor tensors are measured, including their spread in the quantum dot (QD) ensemble. Surprisingly, the electron g factor shows a large anisotropy changing from ge ,x=-1.63 to ge ,z=-2.52 between directions perpendicular and parallel to the dot growth axis, respectively, at an energy of 0.82 eV. The hole g -factor anisotropy at this energy is even stronger: | gh,x|=0.64 and | gh,z|=2.29 . On the other hand, the in-plane anisotropies of electron and hole g factors are small. The pronounced out-of-plane anisotropy is also observed for the spread of the g factors, determined from the spin dephasing time. The hole longitudinal g factors are described with a theoretical model that allows us to estimate the QD parameters. We find that the QD height-to-diameter ratio increases while the indium composition decreases with increasing QD emission energy.

  14. 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

  15. Small molecule aptamer assays based on fluorescence anisotropy signal-enhancer oligonucleotides.

    Science.gov (United States)

    Perrier, Sandrine; Bouilloud, Prisca; De Oliveira Coelho, Gisella; Henry, Mickael; Peyrin, Eric

    2016-08-15

    Herein, we design novel fluorescence anisotropy (FA) aptamer sensing platforms dedicated to small molecule detection. The assay strategy relied on enhanced fluctuations of segmental motion dynamics of the aptamer tracer mediated by an unlabelled, partially complementary oligonucleotide. The signal-enhancer oligonucleotide (SEO) essentially served as a free probe fraction revealer. By targeting specific regions of the signalling functional nucleic acid, the SEO binding to the unbound aptamer triggered perturbations of both the internal DNA flexibility and the localized dye environment upon the free probe to duplex structure transition. This potentiating effect determined increased FA variations between the duplex and target bound states of the aptameric probe. FA assay responses were obtained with both pre-structured (adenosine) and unstructured (tyrosinamide) aptamers and with dyes of different photochemical properties (fluorescein and texas red). The multiplexed analysis ability was further demonstrated through the simultaneous multicolour detection of the two small targets. The FA method appears to be especially simple, sensitive and widely applicable. PMID:27085946

  16. Irreversible magnetic processes under biaxial and uniaxial magnetic anisotropies

    Science.gov (United States)

    Pokharel, S.; Akioya, O.; Alqhtany, N. H.; Dickens, C.; Morgan, W.; Wuttig, M.; Lisfi, A.

    2016-05-01

    Irreversible magnetic processes have been investigated in magnetic systems with two different anisotropy symmetries (uniaxial and biaxial) through angular measurement of the switching field, the irreversible susceptibility and the magnetic viscosity. These two systems consist of two-dimensional cobalt ferrite hetero-structures epitaxially grown on (100) and (110) MgO substrate. It is found that for uniaxial anisotropy the irreversible characteristics of the magnetization are large and display a strong angular dependence, which exhibits its maximum at the easy axis and drops quickly to vanish at the hard axis. However, for biaxial anisotropy the magnetization irreversible characteristics are considerably reduced and are less sensitive to the field angle.

  17. Magnetic anisotropy in geometrically frustrated kagome staircase lattices

    International Nuclear Information System (INIS)

    This paper reviews experimental results concerning magnetic anisotropy in geometrically frustrated kagome staircase lattices. Following problems are discussed: high-temperature susceptibility measurements of kagome single crystals; inelastic neutron scattering measurements on Co3V2O8 single crystals; EPR of Co2+ ions in kagome staircase Mg3V2O8 single crystals. The single-ion anisotropy Hamiltonian is used to analyze experimental results. It is suggested that the magnetic anisotropy in kagome staircase M3V2O8 (M=Co, Ni, Mn) oxides has mainly single-ion origin

  18. Small-scale Anisotropies of Cosmic Rays from Relative Diffusion

    Science.gov (United States)

    Ahlers, Markus; Mertsch, Philipp

    2015-12-01

    The arrival directions of multi-TeV cosmic rays show significant anisotropies at small angular scales. It has been argued that this small-scale structure can naturally arise from cosmic ray scattering in local turbulent magnetic fields that distort a global dipole anisotropy set by diffusion. We study this effect in terms of the power spectrum of cosmic ray arrival directions and show that the strength of small-scale anisotropies is related to properties of relative diffusion. We provide a formalism for how these power spectra can be inferred from simulations and motivate a simple analytic extension of the ensemble-averaged diffusion equation that can account for the effect.

  19. Review of the anisotropy working group at UHECR-2012

    Directory of Open Access Journals (Sweden)

    Ivanov A.

    2013-06-01

    Full Text Available The study of ultra-high energy cosmic rays (UHECRs has recently experienced a jump in statistics as well as improved instrumentation. This has allowed a better sensitivity in searching for anisotropies in the arrival directions of cosmic rays. In this written version of the presentation given by the inter-collaborative “Anisotropy Working Group” at the International Symposium on Future Directions in UHECR physics at CERN in February 2012, we report on the current status for anisotropy searches in the arrival directions of UHECRs.

  20. Dual-probe spectroscopic fingerprints of defects in graphene

    DEFF Research Database (Denmark)

    Settnes, Mikkel; Power, Stephen; Petersen, Dirch Hjorth;

    2014-01-01

    (e.g., an extended graphene sheet). Applying this method, we study the transport anisotropies in pristine graphene sheets, and analyze the spectroscopic fingerprints arising from quantum interference around single-site defects, such as vacancies and adatoms. Furthermore, we demonstrate that the dual......-probe setup is a useful tool for characterizing the electronic transport properties of extended defects or designed nanostructures. In particular, we show that nanoscale perforations, or antidots, in a graphene sheet display Fano-type resonances with a strong dependence on the edge geometry of the perforation....

  1. Role of structural anisotropy of biological tissues in poroelastic wave propagation.

    Science.gov (United States)

    Cardoso, Luis; Cowin, Stephen C

    2012-01-01

    Ultrasound waves have a broad range of clinical applications as a non-destructive testing approach in imaging and in the diagnoses of medical conditions. Generally, biological tissues are modeled as an homogenized equivalent medium with an apparent density through which a single wave propagates. Only the first wave arriving at the ultrasound probe is used for the measurement of the speed of sound. However, the existence of a second wave in tissues such as cancellous bone has been reported and its existence is an unequivocal signature of Biot type poroelastic media. To account for the fact that ultrasound is sensitive to microarchitecture as well as density, a fabric-dependent anisotropic poroelastic ultrasound (PEU) propagation theory was recently developed. Key to this development was the inclusion of the fabric tensor - a quantitative stereological measure of the degree of structural anisotropy of bone - into the linear poroelasticity theory. In the present study, this framework is extended to the propagation of waves in several soft and hard tissues. It was found that collagen fibers in soft tissues and the mineralized matrix in hard tissues are responsible for the anisotropy of the solid tissue constituent through the fabric tensor in the model. PMID:22162897

  2. On the Observation of the Cosmic Ray Anisotropy below 10$^{15}$ eV

    CERN Document Server

    Di Sciascio, G

    2014-01-01

    The measurement of the anisotropy in the arrival direction of cosmic rays is complementary to the study of their energy spectrum and chemical composition to understand their origin and propagation. It is also a tool to probe the structure of the magnetic fields through which cosmic rays travel. As cosmic rays are mostly charged nuclei, their trajectories are deflected by the action of galactic magnetic field they propagate through before reaching the Earth atmosphere, so that their detection carries directional information only up to distances as large as their gyro-radius. If cosmic rays below $10^{15}{\\rm\\,eV}$ are considered and the local galactic magnetic field ($\\sim3{\\rm\\,\\mu G}$) is accounted for, gyro-radii are so short that isotropy is expected. At most, a weak di-polar distribution may exist, reflecting the contribution of the closest CR sources. However, a number of experiments observed an energy-dependent \\emph{"large scale"} anisotropy in the sidereal time frame with an amplitude of about 10$^{-4...

  3. Time delay anisotropy in photoelectron emission from the isotropic ground state of helium

    CERN Document Server

    Heuser, Sebastian; Cirelli, Claudio; Sabbar, Mazyar; Boge, Robert; Lucchini, Matteo; Gallmann, Lukas; Ivanov, Igor; Kheifets, Anatoli S; Dahlström, J Marcus; Lindroth, Eva; Argenti, Luca; Martín, Fernando; Keller, Ursula

    2015-01-01

    Time delays of electrons emitted from an isotropic initial state and leaving behind an isotropic ion are assumed to be angle-independent. Using an interferometric method involving XUV attosecond pulse trains and an IR probe field in combination with a detection scheme, which allows for full 3D momentum resolution, we show that time delays between electrons liberated from the $1s^{2}$ spherically symmetric ground state of He depend on the emission direction of the electrons with respect to the linear polarization axis of the ionizing XUV light. Such time delays can exhibit values as large as 60 attoseconds. With the help of refined theoretical models we can attribute the observed anisotropy to the interplay between different final quantum states, which arise naturally when two photons are involved in the photoionization process. Since most measurement techniques tracing attosecond electron dynamics have involved at least two photons so far, this is a general, significant, and initially unexpected effect that m...

  4. Recovering hidden signals of statistical anisotropy from a masked or partial CMB sky

    CERN Document Server

    Aluri, Pavan K; Rotti, Aditya; Souradeep, Tarun

    2015-01-01

    Any isotropy violating phenomena on cosmic microwave background (CMB) induces off-diagonal correlations in the two-point function. These correlations themselves can be used to estimate the underlying anisotropic signals. Masking due to residual foregrounds, or availability of partial sky due to survey limitation, are unavoidable circumstances in CMB studies. But, masking induces additional correlations, and thus complicates the recovery of such signals. In this work, we discuss a procedure based on bipolar spherical harmonic (BipoSH) formalism to comprehensively addresses any spurious correlations induced by masking and successfully recover hidden signals of anisotropy in observed CMB maps. This method is generic, and can be applied to recover a variety of isotropy violating phenomena. Here, we illustrate the procedure by recovering the subtle Doppler boost signal from simulated boosted CMB skies, which has become possible with the unprecedented full-sky sensitivity of PLANCK probe.

  5. CMB anisotropies from a gradient mode

    Science.gov (United States)

    Mirbabayi, Mehrdad; Zaldarriaga, Matias

    2015-03-01

    A linear gradient mode must have no observable dynamical effect on short distance physics. We confirm this by showing that if there was such a gradient mode extending across the whole observable Universe, it would not cause any hemispherical asymmetry in the power of CMB anisotropies, as long as Maldacena's consistency condition is satisfied. To study the effect of the long wavelength mode on short wavelength modes, we generalize the existing second order Sachs-Wolfe formula in the squeezed limit to include a gradient in the long mode and to account for the change in the location of the last scattering surface induced by this mode. Next, we consider effects that are of second order in the long mode. A gradient mode Φ = qṡx generated in Single-field inflation is shown to induce an observable quadrupole moment. For instance, in a matter-dominated model it is equal to Q = 5(qṡx)2/18. This quadrupole can be canceled by superposition of a quadratic perturbation. The result is shown to be a nonlinear extension of Weinberg's adiabatic modes: a long-wavelength physical mode which looks locally like a coordinate transformation.

  6. Twinning anisotropy of tantalum during nanoindentation

    International Nuclear Information System (INIS)

    Unlike other BCC metals, the plastic deformation of nanocrystalline Tantalum (Ta) during compression is regulated by deformation twinning. Whether or not this twinning exhibits anisotropy was investigated through simulation of displacement-controlled nanoindentation test using molecular dynamics (MD) simulation. MD data was found to correlate well with the experimental data in terms of surface topography and hardness measurements. The mechanism of the transport of material was identified due to the formation and motion of prismatic dislocations loops (edge dislocations) belonging to the 1/2〈111〉 type and 〈100〉 type Burgers vector family. Further analysis of crystal defects using a fully automated dislocation extraction algorithm (DXA) illuminated formation and migration of twin boundaries on the (110) and (111) orientation but not on the (010) orientation and most importantly after retraction all the dislocations disappeared on the (110) orientation suggesting twinning to dominate dislocation nucleation in driving plasticity in tantalum. A significant finding was that the maximum shear stress (critical Tresca stress) in the deformation zone exceeded the theoretical shear strength of Ta (Shear modulus/2π~10.03 GPa) on the (010) orientation but was lower than it on the (110) and the (111) orientations. In light of this, the conventional lore of assuming the maximum shear stress being 0.465 times the mean contact pressure was found to break down at atomic scale

  7. Studies of anisotropy of iron based superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Murphy, Jason A. [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.

  8. Helicon mode driven by O+ thermal anisotropy

    International Nuclear Information System (INIS)

    Preliminary results from an investigation of the helicon instability in a plasma composed of protons, electrons and singly charged oxygen ions, are presented. The velocity distribution function for each plasma component is modeled by a bi-Lorentzian distribution, which allows each particle species to possess a power law tail of arbitrary spectral index. This permits us to model accurately the shape of the power law tails observed on particle species in the plasma sheet region, where the helicon mode is believed to play an important role. The presence of a hard power law tail on the oxygen component is found to dramatically enhance the maximum growth rate of the instability when the oxygen ions possess a small T(parallel)>T(perpendicular) anisotropy. Above a certain value of T(parallel)/T(perpendicular), however, this behavior is reversed. The growth rate decreases as the spectral index of the protons is decreased. The relevance of these effects to the central plasma sheet region is briefly discussed

  9. Surface-Charge Anisotropy of Scheelite Crystals.

    Science.gov (United States)

    Gao, Zhiyong; Hu, Yuehua; Sun, Wei; Drelich, Jaroslaw W

    2016-06-28

    Atomic force microscopy was employed to measure the colloidal interactions between silicon nitride cantilever tips and scheelite crystal surfaces in 1 mM KCl solutions of varying pH. By fitting the Derjguin-Landau-Verwey-Overbeek (DLVO) theoretical model to the recorded force-distance curves, the surface-charge density and surface-potential values were calculated for three crystallographic surfaces including {112}, {101}, and {001}. The calculated surface-potential values were negative in both acidic and basic solutions and varied among crystallographic surfaces. The determined surface-potential values were within zeta-potential values reported in the literature for powdered scheelite minerals. The surface {101} was the most negatively charged surface, followed by {112} and {001}. The surface potential for {001} was only slightly affected by pH, whereas the surface potential for both {112} and {101} increased with increasing pH. Anisotropy in surface-charge density was analyzed in relation to the surface density of active oxygen atoms, that is, the density of oxygen atoms with one or two broken bond(s) within tungstate ions located in the topmost surface layer. On a surface with a higher surface density of active oxygen atoms, a larger number of OH(-) are expected to adsorb through hydrogen bonding, leading to a more negatively charged surface. PMID:27269369

  10. Twinning anisotropy of tantalum during nanoindentation

    Energy Technology Data Exchange (ETDEWEB)

    Goel, Saurav, E-mail: S.GOEL@qub.ac.uk [School of Mechanical and Aerospace Engineering, Queen' s University, Belfast, BT9 5AH (United Kingdom); Beake, Ben [Micro Materials Limited, Willow House, Yale Business Village, Ellice Way, Wrexham LL13 7YL (United Kingdom); Dalton Research Institute, Manchester Metropolitan University, Manchester, M15GD (United Kingdom); Chan, Chi-Wai [School of Mechanical and Aerospace Engineering, Queen' s University, Belfast, BT9 5AH (United Kingdom); Haque Faisal, Nadimul [School of Engineering, Robert Gordon University, Garthdee Road, Aberdeen AB10 7GJ (United Kingdom); Dunne, Nicholas [School of Mechanical and Aerospace Engineering, Queen' s University, Belfast, BT9 5AH (United Kingdom)

    2015-03-11

    Unlike other BCC metals, the plastic deformation of nanocrystalline Tantalum (Ta) during compression is regulated by deformation twinning. Whether or not this twinning exhibits anisotropy was investigated through simulation of displacement-controlled nanoindentation test using molecular dynamics (MD) simulation. MD data was found to correlate well with the experimental data in terms of surface topography and hardness measurements. The mechanism of the transport of material was identified due to the formation and motion of prismatic dislocations loops (edge dislocations) belonging to the 1/2〈111〉 type and 〈100〉 type Burgers vector family. Further analysis of crystal defects using a fully automated dislocation extraction algorithm (DXA) illuminated formation and migration of twin boundaries on the (110) and (111) orientation but not on the (010) orientation and most importantly after retraction all the dislocations disappeared on the (110) orientation suggesting twinning to dominate dislocation nucleation in driving plasticity in tantalum. A significant finding was that the maximum shear stress (critical Tresca stress) in the deformation zone exceeded the theoretical shear strength of Ta (Shear modulus/2π~10.03 GPa) on the (010) orientation but was lower than it on the (110) and the (111) orientations. In light of this, the conventional lore of assuming the maximum shear stress being 0.465 times the mean contact pressure was found to break down at atomic scale.

  11. Issues on generating primordial anisotropies at the end of inflation

    International Nuclear Information System (INIS)

    We revisit the idea of generating primordial anisotropies at the end of inflation in models of inflation with gauge fields. To be specific we consider the charged hybrid inflation model where the waterfall field is charged under a U(1) gauge field so the surface of end of inflation is controlled both by inflaton and the gauge fields. Using δN formalism properly we find that the anisotropies generated at the end of inflation from the gauge field fluctuations are exponentially suppressed on cosmological scales. This is because the gauge field evolves exponentially during inflation while in order to generate appreciable anisotropies at the end of inflation the spectator gauge field has to be frozen. We argue that this is a generic feature, that is, one can not generate observable anisotropies at the end of inflation within an FRW background

  12. Contribution of Bright Extragalactic Radio Sources to Microwave Anisotropy

    CERN Document Server

    Sokasian, A; Smoot, G F; Sokasian, Aaron; Gawiser, Eric; Smoot, George F.

    2001-01-01

    We estimate the contribution of extragalactic radio sources to fluctuations in sky temperature over the range of frequencies (10-300 GHz) used for Cosmic Microwave Background (CMB) anisotropy measurements. CMB anisotropy observations at high resolution and low frequencies are especially sensitive to this foreground. We have compiled a catalog of 2207 bright radio sources, including 758 sources with flux measurements at 90 GHz. We develop a method to extrapolate the source spectra and predict skymaps of extragalactic radio sources at instrument resolutions of 10 arcmin to 10 degrees FWHM. Our results indicate that the brightest sources will dominate microwave anisotropy for a wide range of resolutions and frequencies. Our skymaps predict the location and flux of the brightest radio sources at each frequency, making it straightforward to develop a template for masking the pixels containing them. This masking should be sufficient to protect high resolution CMB anisotropy observations from unacceptable radio sour...

  13. Contribution of extragalactic infrared sources to CMB foreground anisotropy

    CERN Document Server

    Gawiser, E; Gawiser, Eric; Smoot, George F

    1996-01-01

    We estimate the level of confusion of CMB anisotropy measurements caused by extragalactic infrared sources. CMB anisotropy observations at high resolution and high frequencies are especially sensitive to this foreground. We have combined IRAS data on bright infrared galaxies with information about the Galaxy from the DIRBE and FIRAS instruments of COBE. Using the spectrum of the Milky Way as a template, we predict the microwave emission of the 5319 brightest infrared galaxes. We simulate skymaps over the relevant range of frequencies (30-900 GHz) and instrument resolutions (10'-10 degrees Full Width Half Max). Analysis of the temperature anisotropy of these skymaps shows a level of extragalactic infrared foreground that is nearly consistent with previous estimates based on galaxy-evolution models. A reasonable observationalwindow is still available for medium- and small-angular scale CMB anisotropy measurements.

  14. Axisymmetric equilibria with pressure anisotropy and plasma flow

    CERN Document Server

    Evangelias, A

    2016-01-01

    A generalised Grad-Shafranov equation that governs the equilibrium of an axisymmetric toroidal plasma with anisotropic pressure and incompressible flow of arbitrary direction is derived. This equation includes six free surface functions and recovers known Grad-Shafranov-like equations in the literature as well as the usual static, isotropic one. The form of the generalised equation indicates that pressure anisotropy and flow act additively on equilibrium. In addition, two sets of analytical solutions, an extended Solovev one with a plasma reaching the separatrix and an extended Hernegger-Maschke one for a plasma surrounded by a fixed boundary possessing an X-point, are constructed, particularly in relevance to the ITER and NSTX tokamaks. Furthermore, the impacts both of pressure anisotropy and plasma flow on these equilibria are examined. It turns out that depending on the maximum value and the shape of an anisotropy function, the anisotropy can act either paramagnetically or diamagnetically. Also, in most of...

  15. Effects of electron temperature anisotropy on proton mirror instability evolution

    CERN Document Server

    Ahmadi, Narges; Raeder, Joachim

    2016-01-01

    Proton mirror modes are large amplitude nonpropagating structures frequently observed in the magnetosheath. It has been suggested that electron temperature anisotropy can enhance the proton mirror instability growth rate while leaving the proton cyclotron instability largely unaffected, therefore causing the proton mirror instability to dominate the proton cyclotron instability in Earth's magnetosheath. Here, we use particle-in-cell simulations to investigate the electron temperature anisotropy effects on proton mirror instability evolution. Contrary to the hypothesis, electron temperature anisotropy leads to excitement of the electron whistler instability. Our results show that the electron whistler instability grows much faster than the proton mirror instability and quickly consumes the electron free energy, so that there is no electron temperature anisotropy left to significantly impact the evolution of the proton mirror instability.

  16. Electric Field Induced Magnetic Anisotropy in a Ferromagnet

    Energy Technology Data Exchange (ETDEWEB)

    Gamble, S. J.

    2010-02-24

    We report the first observation of a transient all electric field induced magnetic anisotropy in a thin film metallic ferromagnet. We generate the anisotropy with a strong (-10{sup 9} V/m) and short (70 fs) {rvec E}-field pulse. This field is large enough to distort the valence charge distribution in the metal, yet its duration is too brief to change the atomic positions. This pure electronic structure alteration of the sample generates a new type of transient anisotropy axis and strongly influences the magnetization dynamics. The successful creation of such an anisotropy opens the possibility for all {rvec E}-field induced magnetization reversal in thin metallic films - a greatly desired yet unachieved process.

  17. Tuning Exchange Anisotropy of Exchange-Biased System

    Institute of Scientific and Technical Information of China (English)

    XU Yan; HU Jing-Guo; R.L.Stamps

    2008-01-01

    Exchange anisotropy in FM/AFM bilayers has given a lot of static magnetization properties such as enhanced coercivity and magnetization loop shifts.These phenomena are primarily from the effective anisotropies intro-duced into a ferromagnet by exchange coupling with a strongly anisotropic antiferromagnet.These effective anisotropies can also be used to explain the dynamic consequences of exchange-biased bilayers.In this article,the dynamic con-sequences such as exchange-induced susceptibility,exchange-induced permeability,and the corresponding domain wall characteristics in the exchange-biased structures of ferromagnet/antiferromagnetl/antiferromagnet2 are studied.The results show that the second antiferromagnetic layer can largely affect the dynamic consequences of exchange-biased bilayers.Especially in the ease of critical temperature,the effects become more obvious.Practically,the exchange anisotropy of biased bilayer system can be tuned by exchange coupling with the second antiferromagnetic layer.

  18. Axisymmetric equilibria with pressure anisotropy and plasma flow

    CERN Document Server

    Evangelias, Achilleas

    2016-01-01

    In this Master thesis we investigate the influence of pressure anisotropy and incompressible flow of arbitrary direction on the equilibrium properties of magnetically confined, axisymmetric toroidal plasmas. The main novel contribution is the derivation of a pertinent generalised Grad-Shafranov equation. This equation includes six free surface functions and recovers known Grad-Shafranov-like equations in the literature as well as the usual static, isotropic one. The form of the generalised equation indicates that pressure anisotropy and flow act additively on equilibrium. In addition, two sets of analytical solutions, an extended Solovev one with a plasma reaching the separatrix and an extended Hernegger-Maschke one for a plasma surrounded by a fixed boundary possessing an X-point, are constructed, particularly in relevance to the ITER and NSTX tokamaks. Furthermore, the impacts both of pressure anisotropy, through an anisotropy function assumed to be uniform on the magnetic surfaces, and plasma flow, via the...

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

    CERN Document Server

    Santo-Lima, R; Pino, E M de Gouveia Dal; Lazarian, A

    2016-01-01

    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 MHD turbulence shows a very different statistical behaviour from the isotropic (standard) one and is unable to amplify seed magnetic fields, in disagreement with previous cosmological MHD simulations which are able to explain the observed magnetic fields in the ICM. On the other hand, temperature anisotropy can also drive kinetic instabilities which grow faster near the ions kinetic scales. Observations from the solar wind suggest that these micro- instabilities scatter the ions, thus relaxing the anisotropy. This work aims to compare this relaxation rate with the growth rate of the anisotropies driven by the turbulence. We employ quasilinear theory to estimate the scattering rate provided by...

  20. An evaluation of mechanical anisotropy of Zircaloy using (impression testing)

    International Nuclear Information System (INIS)

    A knowledge of the mechanical anisotropy is important for predictability of dimensional changes and stability of fuel rods in service. In addition, the anisotropy parameters control formability and the ease with which Zircaloy tubing can be pilgered from tube-reduced extrusions (TREX). The mechanical anisotropy parameters are usually determined using tensile and internal pressurization tests while monitoring the biaxial (hoop and axial) strains; the parameters are evaluated INDIRECTLY from stresses and strains. We report here the application of the recently developed impression test method in evaluating these anisotropy parameters relatively more DIRECTLY from yield and flow stresses along the three orthogonal directions, namely axial, hoop and radial directions of the tubing. In addition, this type of testing can be made on relatively small specimens, which is of great advantage in investigating radiation effects on materials

  1. Primordial Statistical Anisotropies: The Effective Field Theory Approach

    CERN Document Server

    Abolhasani, Ali Akbar; Emami, Razieh; Firouzjahi, Hassan

    2015-01-01

    In this work we present the effective field theory of primordial statistical anisotropies generated during anisotropic inflation involving a background $U(1)$ gauge field. Besides the usual Goldstone boson associated with the breaking of time diffeomorphism we have two additional Goldstone bosons associated with the breaking of spatial diffeomorphisms. We further identify these two new Goldstone bosons with the expected two transverse degrees of the $U(1)$ gauge field fluctuations. Upon defining the appropriate unitary gauge, we present the most general quadratic action which respects the remnant symmetry in the unitary gauge. The interactions between various Goldstone bosons leads to statistical anisotropy in curvature perturbation power spectrum. Calculating the general results for power spectrum anisotropy, we recover the previously known results in specific models of anisotropic inflation. In addition, we present novel results for statistical anisotropy in models with non-trivial sound speed for inflaton ...

  2. Small-scale anisotropies of cosmic rays from relative diffusion

    CERN Document Server

    Mertsch, Philipp

    2015-01-01

    The arrival directions of multi-TeV cosmic rays show significant anisotropies at small angular scales. It has been argued that this small scale structure is reflecting the local, turbulent magnetic field in the presence of a global dipole anisotropy in cosmic rays as determined by diffusion. This effect is analogous to weak gravitational lensing of temperature fluctuations of the cosmic microwave background. We show that the non-trivial power spectrum in this setup can be related to the properties of relative diffusion and we study the convergence of the angular power spectrum to a steady-state as a function of backtracking time. We also determine the steady-state solution in an analytical approach based on a modified BGK ansatz. A rigorous mathematical treatment of the generation of small scale anisotropies will help in unraveling the structure of the local magnetic field through cosmic ray anisotropies.

  3. Searches for Anisotropy of Cosmic Rays with the Telescope Array

    Science.gov (United States)

    Cady, Robert; Telescope Array Collaboration

    2016-03-01

    With over seven years of data from the TA surface detector array, we will present the results of various searches for anisotropies in the arrival direction of cosmic rays, including an update of the hotspot above 57 EeV.

  4. ORIGIN OF COBALT ANISOTROPY IN RARE EARTH-COBALT INTERMETALLICS

    OpenAIRE

    Ballou, Rafik; Lemaire, R.

    1988-01-01

    The strong cobalt anisotropies in rare earth-cobalt intermetallics are shown to arise from orbitally selective 3d band energy dispersion due to either chain like or layered like cobalt staking rather than from usual crystal field effect.

  5. Dipole interactions with random anisotropy in a frozen ferrofluid

    OpenAIRE

    Luo, Weili; Nagel, S. R.; Rosenbaum, T.F.; Rosensweig, R. E.

    1991-01-01

    Glassy behavior (including hysteresis, irreversibility, a peak in the zero-field-cooled magnetization, and nonexponential relaxation) is observed in a quenched ferrofluid system consisting of 50-angstrom magnetite particles. An Arrott plot, M^2 vs H/M, shows clear features of random anisotropy similar to what is found in amorphous ferromagnets. We discuss the glassy behavior in terms of both the random anisotropy and the dipole interactions, and we contrast the unusual response of our system ...

  6. Anisotropy signature in extended images from reverse-time migration

    KAUST Repository

    Sava, Paul

    2012-11-04

    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 (CIPs), carry enough information to characterize the angle-dependent illumination and to provide measurements for migration velocity analysis. Furthermore, inaccurate anisotropy leaves a distinctive signature in CIPs, which can be used to evaluate anisotropy through techniques similar to the ones used in conventional wavefield tomography.

  7. Topographical Anisotropy and Wetting of Ground Stainless Steel Surfaces

    OpenAIRE

    Cornelia Bellmann; Alfredo Calvimontes; Marc Mauermann

    2012-01-01

    Microscopic and physico-chemical methods were used for a comprehensive surface characterization of different mechanically modified stainless steel surfaces. The surfaces were analyzed using high-resolution confocal microscopy, resulting in detailed information about the topographic properties. In addition, static water contact angle measurements were carried out to characterize the surface heterogeneity of the samples. The effect of morphological anisotropy on water contact angle anisotropy w...

  8. Contribution of Bright Extragalactic Radio Sources to Microwave Anisotropy

    OpenAIRE

    Sokasian, Aaron; Gawiser, Eric; Smoot, George F.

    1998-01-01

    We estimate the contribution of extragalactic radio sources to fluctuations in sky temperature over the range of frequencies (10-300 GHz) used for Cosmic Microwave Background (CMB) anisotropy measurements. CMB anisotropy observations at high resolution and low frequencies are especially sensitive to this foreground. We have compiled a catalog of 2207 bright radio sources, including 758 sources with flux measurements at 90 GHz. We develop a method to extrapolate the source spectra and predict ...

  9. Contribution of Extragalactic Infrared Sources to CMB Foreground Anisotropy

    OpenAIRE

    Gawiser, Eric; Smoot, George F.

    1996-01-01

    We estimate the level of confusion to Cosmic Microwave Background anisotropy measurements caused by extragalactic infrared sources. CMB anisotropy observations at high resolution and high frequencies are especially sensitive to this foreground. We use data from the COBE satellite to generate a Galactic emission spectrum covering mm and sub-mm wavelengths. Using this spectrum as a template, we predict the microwave emission of the 5319 brightest infrared galaxies seen by IRAS. We simulate skym...

  10. Anisotropy of thermal diffusivity in the upper mantle

    OpenAIRE

    Tommasi, A.; Gibert, B.; U. Seipold; Mainprice, D.;  

    2001-01-01

    Heat transfer in the mantle is a key process controlling the Earth's dynamics. Upper-mantle mineral phases, especially olivine, have been shown to display highly anisotropic thermal diffusivity at ambient conditions, and seismic anisotropy data show that preferred orientations of olivine induced by deformation are coherent at large scales (>50 km) in the upper mantle. Thus heat transport in the upper mantle should be anisotropic. But the thermal anisotropy of mantle minerals at high temperatu...

  11. Magnetic anisotropies of late transition metal atomic clusters

    OpenAIRE

    Fernández-Seivane, Lucas; Ferrer, Jaime

    2006-01-01

    We analyze the impact of the magnetic anisotropy on the geometric structure and magnetic ordering of small atomic clusters of palladium, iridium, platinum and gold, using Density Functional Theory. Our results highlight the absolute need to include self-consistently the spin orbit interaction in any simulation of the magnetic properties of small atomic clusters, and a complete lack of universality in the magnetic anisotropy of small-sized atomic clusters.

  12. Anisotropy of magnetic emulsions induced by magnetic and electric fields

    OpenAIRE

    Dikansky, Yury I.; Tyatyushkin, Alexander N.; Zakinyan, Arthur R.

    2011-01-01

    The anisotropy of magnetic emulsions induced by simultaneously acting electric and magnetic fields is theoretically and experimentally investigated. Due to the anisotropy, the electric conductivity and magnetic permeability of a magnetic emulsion are no longer scalar coefficients, but are tensors. The electric conductivity and magnetic permeability tensors of sufficiently diluted emulsions in sufficiently weak electric and magnetic fields are found as functions of the electric and magnetic in...

  13. Markarian galaxies and the anisotropy of the Hubble constant

    International Nuclear Information System (INIS)

    Taking into account all the observational data of Markarian galaxies, problems of redshifts can be studied with a sample from rather numerous sources. A test on their distribution in the sky confirms the significant anisotropy of the Hubble constant: this anisotropy was, in fact, observed for the first time by Rubin, Ford and Rubin, and confirmed by Le Denmat and Vigier with type I supernovae galaxies

  14. Polarimetric investigation of materials with both linear and circular anisotropy

    DEFF Research Database (Denmark)

    Naydenova, I.; Nikolova, L.; Todorov, T.; Andruzzi, F.; Hvilsted, Søren; Ramanujam, P.S.

    1997-01-01

    We investigate light propagation through materials with both linear and circular anisotropy and find the relation of the amplitude and polarization transfer functions to the four anisotropic characteristics: linear circular birefringence, and linear and circular dichroism. We determine these four...... characteristics of anisotropic samples by measuring the output intensity and polarization corresponding to different input polarization azimuths and fitting the theoretical and experimental results. In our experiments we have used films of side-chain azobenzene polyesters in which optical anisotropy had been...

  15. The Concept of Mean Anisotropy of Signals with Nonzero Mean

    Czech Academy of Sciences Publication Activity Database

    Kurdyukov, A.; Kustov, A.; Tchaikovsky, M.; Kárný, Miroslav

    Bratislava: Slovak University of Technology in Bratislava, 2013 - (Fikar, M.; Kvasnica, M.) ISBN 978-80-227-3951-1. [19th International Conference on Process Control. Strbske Pleso (SK), 18.06.2013-21.06.2013] Institutional support: RVO:67985556 Keywords : anisotropy * control Subject RIV: BB - Applied Statistics, Operational Research http://library.utia.cas.cz/separaty/2013/AS/karny-the concept of mean anisotropy of signals with nonzero mean.pdf

  16. Anisoft 4.2. – Anisotropy data browser

    Czech Academy of Sciences Publication Activity Database

    Chadima, Martin; Jelínek, V.

    2008-01-01

    Roč. 38, special issue (2008), s. 41-41. ISSN 1335-2806. [Paleo, Rock and Environmental Magnetism. Castle Meeting /11./. 22.06.2008-28.06.2008, Bojnice] R&D Projects: GA AV ČR IAA300130612 Institutional research plan: CEZ:AV0Z30130516 Keywords : anisotropy of magnetic susceptibility * tensor statisticsntation * anisotropy of magnetic remanence Subject RIV: DE - Earth Magnetism, Geodesy , Geography http://gauss.savba.sk/GPIweb/conferences/nt2008/abstr/Chadima-2.pdf

  17. In-plane anisotropy of 1545 aluminum alloy sheet

    Institute of Scientific and Technical Information of China (English)

    PENG Yong-yi; YIN Zhi-min; YANG Jin; DU Yu-xuan

    2005-01-01

    The microstructures and the tensile mechanical properties in the rolling plane of 1545 aluminum alloy sheet at different orientations with respect to the rolling direction were studied by means of tensile test,X-ray diffractometer(XRD),optical microscope and transmission electron microscope.The in-plane anisotropy of tensile mechanical properties was calculated and the inverse pole figures of the rolling plane,transversal section and longitudinal section were obtained by Harris method.The results show that the 1545 Al alloy sheet has remarkable in-plane anisotropy of mechanical properties and the main texture component is{110}texture.On the basis of the model that regards the sheet containing only{110}texture as a monocrystal,the relationship of in-plane anisotropy and the anisotropy of crystallography was analyzed.The study shows that it is the combined effects of the anisotropy of crystallography and microstructures that cause the in-plane anisotropy of mechanical properties,but the main cause is the crystallographic texture.

  18. Physical modelling of elastic anisotropy in porous media

    Energy Technology Data Exchange (ETDEWEB)

    Furre, Anne-Kari

    1997-12-31

    During the last decades, anisotropy has become increasingly interesting in hydrocarbon prospecting. Knowledge of anisotropy in the subsurface can improve reservoir production and data interpretation. This thesis presents experimental studies of three different artificial anisotropic media: layered materials, isotropic matrix with stress-induced fractures, and layered media with controlled crack patterns at an oblique angle relative to layering. Layered media were constructed by varying grain size distributions for different layers, which resulted in acoustic and permeability anisotropy. The thin layer materials could be described by Backus modelling provided the wavelength was much larger than the layer periods. Frequency dependent scattering was observed for waves travelling normal to the layers. Saturated wave velocities were consistent with transverse isotropic Biot theory, but because the permeability anisotropy was small, no flow dependent attenuation anisotropy was observed. When sandstones were cemented under stress and then released, to simulate a vertical core or uplift process, predominantly horizontal cracks developed in the samples. On reloading to the cementing stress level, the velocities were below the initial values, which supports the theories of crack growth. In further triaxial tests on the same material a stress-dependent anisotropy occurred similar to what is often seen in natural samples taken from large depths. 70 refs., 200 figs., 56 tabs.

  19. Anisotropy of magnetic susceptibility in alkali feldspar and plagioclase

    Science.gov (United States)

    Biedermann, Andrea R.; Pettke, Thomas; Angel, Ross J.; Hirt, Ann M.

    2016-04-01

    Feldspars are the most abundant rock-forming minerals in the Earth's crust, but their magnetic properties have not been rigorously studied. This work focuses on the intrinsic magnetic anisotropy of 31 feldspar samples with various chemical compositions. Because feldspar is often twinned or shows exsolution textures, measurements were performed on twinned and exsolved samples as well as single crystals. The anisotropy is controlled by the diamagnetic susceptibility and displays a consistent orientation of principal susceptibility axes; the most negative or minimum susceptibility is parallel to [010], and the maximum (least negative) is close to the crystallographic [001] axis. However, the magnetic anisotropy is weak when compared to other rock-forming minerals, 1.53 × 10-9 m3 kg-1 at maximum. Therefore, lower abundance minerals, such as augite, hornblende or biotite, often dominate the bulk paramagnetic anisotropy of a rock. Ferromagnetic anisotropy is not significant in most samples. In the few samples that do show ferromagnetic anisotropy, the principal susceptibility directions of the ferromagnetic subfabric do not display a systematic orientation with respect to the feldspar lattice. These results suggest that palaeointensity estimates of the geomagnetic field made on single crystals of feldspar will not be affected by a systematic orientation of the ferromagnetic inclusions within the feldspar lattice.

  20. Anisotropy of eddy variability in the global ocean

    Science.gov (United States)

    Stewart, K. D.; Spence, P.; Waterman, S.; Sommer, J. Le; Molines, J.-M.; Lilly, J. M.; England, M. H.

    2015-11-01

    The anisotropy of eddy variability in the global ocean is examined in geostrophic surface velocities derived from satellite observations and in the horizontal velocities of a 1/12° global ocean model. Eddy anisotropy is of oceanographic interest as it is through anisotropic velocity fluctuations that the eddy and mean-flow fields interact dynamically. This study is timely because improved observational estimates of eddy anisotropy will soon be available with Surface Water and Ocean Topography (SWOT) altimetry data. We find there to be good agreement between the characteristics and distributions of eddy anisotropy from the present satellite observations and model ocean surface. In the model, eddy anisotropy is found to have significant vertical structure and is largest close to the ocean bottom, where the anisotropy aligns with the underlying isobaths. The highly anisotropic bottom signal is almost entirely contained in the barotropic variability. Upper-ocean variability is predominantly baroclinic and the alignment is less sensitive to the underlying bathymetry. These findings offer guidance for introducing a parameterization of eddy feedbacks, based on the eddy kinetic energy and underlying bathymetry, to operate on the barotropic flow and better account for the effects of barotropic Reynolds stresses unresolved in coarse-resolution ocean models.

  1. Magnetic anisotropies of (Ga,Mn)As films and nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Hoffmann, Frank

    2011-02-02

    In this work the magnetic anisotropies of the diluted magnetic semiconductor (Ga,Mn)As were investigated experimentally. (Ga,Mn)As films show a superposition of various magnetic anisotropies which depend sensitively on various parameters such as temperature, carrier concentration or lattice strain. However, the anisotropies of lithographically prepared (Ga,Mn)As elements differ significantly from an unpatterned (Ga,Mn)As film. In stripe-shaped structures this behaviour is caused by anisotropic relaxation of the compressive lattice strain. In order to determine the magnetic anisotropies of individual (Ga,Mn)As nanostructures a combination of ferromagnetic resonance and time-resolved scanning Kerr microscopy was employed in this thesis. In addition, local changes of the magnetic anisotropy in circular and rectangular structures were visualized by making use of spatially resolved measurements. Finally, also the influence of the laterally inhomogeneous magnetic anisotropies on the static magnetic properties, such as coercive fields, was investigated employing spatially resolved static MOKE measurements on individual (Ga,Mn)As elements. (orig.)

  2. Slow shock formation and temperature anisotropy in collisionless magnetic reconnection

    Science.gov (United States)

    Higashimori, K.; Hoshino, M.

    2011-12-01

    We perform a two-dimensional simulation by using an electromagnetic hybrid code to study the formation of slow-mode shocks in collisionless magnetic reconnection in low beta plasmas, and we argue that one of important agents of the formation of slow shocks is the ion temperature anisotropy enhanced at the shock downstream region. As magnetic reconnection develops, it is known that the parallel temperature along the magnetic field becomes large in association with the anisotropic PSBL ion beams, and this temperature anisotropy has a tendency to suppress the formation of slow shock. Although preceding studies on magnetic reconnection with kinetic codes have shown such ion temperature anisotropy along the reconnection layer, the direct relation between formation of slow shocks and the ion temperature anisotropy has not been investigated. Based on our simulation result, we found that the slow shock formation is suppressed due to the large temperature anisotropy near the X-type region, but the downstream ion temperature anisotropy relaxes with increasing the distance from the magnetic neutral point. As a result, two pairs of current structures, which are the strong evidence of dissipation of magnetic field in slow shocks, are formed at the distance |x| > 115 λ i from the neutral point.

  3. Characterization of optical anisotropy in quantum wells under compressive anisotropic in-plane strain

    Energy Technology Data Exchange (ETDEWEB)

    Biermann, Mark L [Physics Department, 566 Brownson Rd., U.S. Naval Academy, Annapolis, MD 21402 (United States); Walters, Matthew [Physics Department, 566 Brownson Rd., U.S. Naval Academy, Annapolis, MD 21402 (United States); Diaz-Barriga, James [Physics Department, 566 Brownson Rd., U.S. Naval Academy, Annapolis, MD 21402 (United States); Rabinovich, W S [Naval Research Laboratory, Code 5652, 4555 Overlook Ave. SW, Washington, DC 20375-5320 (United States)

    2003-10-21

    Anisotropic in-plane strain in quantum wells leads to an optical polarization anisotropy that can be exploited for device applications. We have determined that for many anisotropic compressive strain cases, the dependence of the optical anisotropy is linear in the strain anisotropy. This result holds for a variety of well and barrier materials and widths and for various overall strain conditions. Further, the polarization anisotropy per strain anisotropy varies as the reciprocal of the energy separation of the relevant hole sub-bands. Hence, a general result for the polarization anisotropy per strain anisotropy is available for cases of compressive anisotropic in-plane strain.

  4. An Ultrasonographic Periodontal Probe

    Science.gov (United States)

    Bertoncini, C. A.; Hinders, M. K.

    2010-02-01

    Periodontal disease, commonly known as gum disease, affects millions of people. The current method of detecting periodontal pocket depth is painful, invasive, and inaccurate. As an alternative to manual probing, an ultrasonographic periodontal probe is being developed to use ultrasound echo waveforms to measure periodontal pocket depth, which is the main measure of periodontal disease. Wavelet transforms and pattern classification techniques are implemented in artificial intelligence routines that can automatically detect pocket depth. The main pattern classification technique used here, called a binary classification algorithm, compares test objects with only two possible pocket depth measurements at a time and relies on dimensionality reduction for the final determination. This method correctly identifies up to 90% of the ultrasonographic probe measurements within the manual probe's tolerance.

  5. Hard probes 2006 Asilomar

    CERN Multimedia

    2006-01-01

    "The second international conference on hard and electromagnetic probes of high-energy nuclear collisions was held June 9 to 16, 2006 at the Asilomar Conference grounds in Pacific Grove, California" (photo and 1/2 page)

  6. Weak-anisotropy approximations of P-wave phase and ray velocities for anisotropy of arbitrary symmetry

    Czech Academy of Sciences Publication Activity Database

    Farra, V.; Pšenčík, Ivan

    2016-01-01

    Roč. 60 (2016). ISSN 0039-3169 Institutional support: RVO:67985530 Keywords : weak anisotropy * P-wave * phase velocity * ray velocity Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 0.806, year: 2014

  7. Can modified gravity models reconcile the tension between CMB anisotropy and lensing maps in Planck-like observations?

    CERN Document Server

    Hu, Bin

    2015-01-01

    Planck-2015 data seem to favour a large value of the lensing amplitude parameter, $A_{\\rm L}=1.22\\pm0.10$, in CMB spectra. This result is in $2\\sigma$ tension with the lensing reconstruction result, $A_{\\rm L}^{\\phi\\phi}=0.95\\pm0.04$. In this paper, we simulate several CMB anisotropy and CMB lensing spectra based on Planck-2015 best-fit cosmological parameter values and Planck blue book beam and noise specifications. We analyse several modified gravity models within the effective field theory framework against these simulations and find that models whose effective Newton constant is enhanced can modulate the CMB anisotropy spectra in a way similar to that of the $A_{\\rm L}$ parameter. However, in order to lens the CMB anisotropies sufficiently, like in the Planck-2015 results, the growth of matter perturbations is substantially enhanced and gives a high $\\sigma_8$ value. This in turn proves to be problematic when combining these data to other probes, like weak lensing from CFHTLenS, that favour a smaller ampl...

  8. Quenching and anisotropy of hydromagnetic turbulent transport

    International Nuclear Information System (INIS)

    Hydromagnetic turbulence affects the evolution of large-scale magnetic fields through mean-field effects like turbulent diffusion and the α effect. For stronger fields, these effects are usually suppressed or quenched, and additional anisotropies are introduced. Using different variants of the test-field method, we determine the quenching of the turbulent transport coefficients for the forced Roberts flow, isotropically forced non-helical turbulence, and rotating thermal convection. We see significant quenching only when the mean magnetic field is larger than the equipartition value of the turbulence. Expressing the magnetic field in terms of the equipartition value of the quenched flows, we obtain for the quenching exponents of the turbulent magnetic diffusivity about 1.3, 1.1, and 1.3 for Roberts flow, forced turbulence, and convection, respectively. However, when the magnetic field is expressed in terms of the equipartition value of the unquenched flows, these quenching exponents become about 4, 1.5, and 2.3, respectively. For the α effect, the exponent is about 1.3 for the Roberts flow and 2 for convection in the first case, but 4 and 3, respectively, in the second. In convection, the quenching of turbulent pumping follows the same power law as turbulent diffusion, while for the coefficient describing the Ω×J effect nearly the same quenching exponent is obtained as for α. For forced turbulence, turbulent diffusion proportional to the second derivative along the mean magnetic field is quenched much less, especially for larger values of the magnetic Reynolds number. However, we find that in corresponding axisymmetric mean-field dynamos with dominant toroidal field the quenched diffusion coefficients are the same for the poloidal and toroidal field constituents.

  9. Anisotropy in electron-atom collisions

    International Nuclear Information System (INIS)

    Most of the work described in this thesis deals with studies using coincidence experiments, particularly for investigating the electron impact excitation of the 21P and 31D states in helium. A peculiarity is that in the 31D studies the directly emitted 31D → 21P photons are not observed but the 21P → 11S photons resulting from the 31D → 21P → 11S cascade instead. Another interesting point is the choice of the quantisation axis. The author demonstrates that it is of great advantage to take the quantisation axis perpendicular to the scattering plane rather than in the direction of the incident beam, as was done (on historical grounds) in previously reported electron-photon coincidence experiments. Contrary to the incident beam direction the axis perpendicular to the scattering plane really represents an axis of symmetry in the coincidence experiment. In Chapter II the so-called 'parity unfavoured' excitation of the (2p2)3P state of helium by electrons is studied. In chapter III the anisotropy parameters for the electron impact excitation of the 21P state of helium in the energy range from 26.6 to 40 eV and in the angular range from 300 to 1100 are determined. Chapter IV contains a description of a scattered electron cascaded-photon coincidence experiment on the electron impact excitation of helium's 31D state. The measurement of complex scattering amplitudes for electron impact excitation of the 31D and 31P states of helium is discussed in Chapter V. (Auth./C.F.)

  10. Electrical conductivity anisotropy in partially molten peridotite under shear deformation

    Science.gov (United States)

    Zhang, Baohua; Yoshino, Takashi; Yamazaki, Daisuke; Manthilake, Geeth; Katsura, Tomoo

    2014-11-01

    The electrical conductivity of partially molten peridotite was measured during deformation in simple shear at 1 GPa in a DIA type apparatus with a uniaxial deformation facility. To detect development of electrical anisotropy during deformation of partially molten system, the electrical conductivity was measured simultaneously in two directions of three principal axes: parallel and normal to the shear direction on the shear plane, and perpendicular to the shear plane. Impedance spectroscopy measurement was performed at temperatures of 1523 K for Fe-bearing and 1723 K for Fe-free samples, respectively, in a frequency range from 0.1 Hz to 1 MHz. The electrical conductivity of partially molten peridotite parallel to shear direction increased to more than one order of magnitude higher than those normal to shear direction on the shear plane. This conductivity difference is consistent with the magnitude of the conductivity anisotropy observed in the oceanic asthenosphere near the Eastern Pacific Rise. On the other hand, conductivity perpendicular to the shear plane decreased gradually after the initiation of shear and finally achieved a value close to that of olivine. The magnitude and development style of conductivity anisotropy was almost the same for both Fe-bearing and Fe-free melt-bearing systems, and also independent of shear strain. However, such conductivity anisotropy was not developed in melt-free samples during shear deformation, suggesting that the conductivity anisotropy requires a presence of partial melting under shear stress. Microstructural observations of deformed partially molten peridotite samples demonstrated that conductivity anisotropy was attributed to the elongation of melt pockets parallel to the shear direction. Horizontal electrical conductivity anisotropy revealed by magnetotelluric surveys in the oceanic asthenosphere can be well explained by the realignment of partial melt induced by shear stress.

  11. Global inversion for anisotropy during full-waveform inversion

    Science.gov (United States)

    Debens, H. A.; Warner, M.; Umpleby, A.

    2015-12-01

    Full-waveform inversion (FWI) is a powerful tool for quantitative estimation of high-resolution high-fidelity models of subsurface seismic parameters, typically P-wave velocity. The solution to FWI's posed nonlinear inverse problem is obtained via an iterative series of linearized local updates to a start model, assuming this model lies within the basin of attraction to the global minimum. Thanks to many successful published applications to three-dimensional (3D) field datasets, its advance has been rapid and driven in large-part by the oil and gas industry. The consideration of seismic anisotropy during FWI is of vital importance, as it holds influence over both the kinematics and dynamics of seismic waveforms. If not appropriately taken into account then inadequacies in the anisotropy model are likely to manifest as significant error in the recovered velocity model. Conventionally, anisotropic FWI employs either an a priori anisotropy model, held fixed during FWI, or it uses a multi-parameter local inversion scheme to recover the anisotropy as part of the FWI; both of these methods can be problematic. Constructing an anisotropy model prior to FWI often involves intensive (and hence expensive) iterative procedures, such as travel-time tomography or moveout velocity analysis. On the other hand, introducing multiple parameters to FWI itself increases the complexity of what is already an underdetermined inverse problem. We propose that global rather than local FWI can be used to recover the long-wavelength acoustic anisotropy model, and that this can then be followed by more-conventional local FWI to recover the detailed model. We validate this approach using a full 3D field dataset, demonstrating that it avoids problems associated to crosstalk that can bedevil local inversion schemes, and reconciles well with in situ borehole measurements. Although our approach includes a global inversion for anisotropy, it is nonetheless affordable and practical for 3D field data.

  12. Model for resonant plasma probe.

    Energy Technology Data Exchange (ETDEWEB)

    Warne, Larry Kevin; Johnson, William Arthur; Hebner, Gregory Albert; Jorgenson, Roy E.; Coats, Rebecca Sue

    2007-04-01

    This report constructs simple circuit models for a hairpin shaped resonant plasma probe. Effects of the plasma sheath region surrounding the wires making up the probe are determined. Electromagnetic simulations of the probe are compared to the circuit model results. The perturbing effects of the disc cavity in which the probe operates are also found.

  13. A small dimension intraoperative probe

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    This article introduces the usage of the intraoperative probe in surgical based on RGS and proposes one method to design the probe. Also, a charge-sensitive preamplifier used in semiconductor detector was constructed which can reduce the dimension of the probe. At last the probe is tested by some animal experiments. Results showed that the property of this system are reliable.

  14. Thermocouple probe manufacturing

    International Nuclear Information System (INIS)

    Thermocouple probe for high temperature measuring was carried out. Aim of this experiment is to refunction of the thermocouple, so this thermocouple can be used for measuring temperature. Probe is made of stainless steel pipe in which that size are 53 cm length, 0,25 cm thick, and 2,24 cm of outer diameter. One ending of the probe was closed off by a piece of stainless steel in which the welding process was carried out on this connection. After probe was integrated on the thermocouple, calibration of this system was investigated. A process of comparing between this thermocouple to the oven thermocouple is a method for calibration. Oven temperature was increased from 150°C up to 700°C in 50°C intervals. Result of this experiment show that thermocouple covered by stainless steel has a deviation of 0,7 % - 6,7 %. Conclusion of thi activity is that thermocouple covered by stainless steel probe is suitable for measuring temperature. (author)

  15. Evaluation of a multi-electrode bioimpedance spectroscopy tensor probe to detect the anisotropic conductivity spectra of biological tissues

    International Nuclear Information System (INIS)

    This paper presents bioimpedance spectroscopy measurements of anisotropic tissues using a 16 electrode probe and reconstruction method of estimating the anisotropic impedance spectrum in a local region just underneath the center of the probe. This may enable in-vivo surface bioimpedance measurements with similar performance to the ex-vivo gold standard that requires excising and placing the entire tissue sample in a unit measurement cell with uniform electric field. The multiple surface electrodes enable us to create a focused current pattern so that the resulting measured voltage is more sensitive to a local region and less sensitive to other areas. This is exploited in a reconstruction method to provide improved bioimpedance and anisotropy measurements. In this paper, we describe the current pattern for localized electrical energy concentration, performance with the spring loaded pin electrodes, data calibration and experimental results on anisotropic agar phantoms and different tissue types. The anisotropic conductivity spectra are able to differentiate insulating films of different thickness and detect their orientation. Bioimpedance spectra of biological tissues are in agreement with published data and reference instruments. The anisotropy expressed as the ratio of eigenvalues and the orientation of eigenfunctions were reconstructed at 45° intervals. This information is used to predict the underlying anisotropy of the region under the probe. Tissue measurements clearly demonstrate the expected higher anisotropy of muscle tissue compared to liver tissue and spectral changes. (paper)

  16. Evaluation of a multi-electrode bioimpedance spectroscopy tensor probe to detect the anisotropic conductivity spectra of biological tissues

    Science.gov (United States)

    Karki, Bishal; Wi, Hun; McEwan, Alistair; Kwon, Hyeuknam; In Oh, Tong; Woo, Eung Je; Seo, Jin Keun

    2014-07-01

    This paper presents bioimpedance spectroscopy measurements of anisotropic tissues using a 16 electrode probe and reconstruction method of estimating the anisotropic impedance spectrum in a local region just underneath the center of the probe. This may enable in-vivo surface bioimpedance measurements with similar performance to the ex-vivo gold standard that requires excising and placing the entire tissue sample in a unit measurement cell with uniform electric field. The multiple surface electrodes enable us to create a focused current pattern so that the resulting measured voltage is more sensitive to a local region and less sensitive to other areas. This is exploited in a reconstruction method to provide improved bioimpedance and anisotropy measurements. In this paper, we describe the current pattern for localized electrical energy concentration, performance with the spring loaded pin electrodes, data calibration and experimental results on anisotropic agar phantoms and different tissue types. The anisotropic conductivity spectra are able to differentiate insulating films of different thickness and detect their orientation. Bioimpedance spectra of biological tissues are in agreement with published data and reference instruments. The anisotropy expressed as the ratio of eigenvalues and the orientation of eigenfunctions were reconstructed at 45° intervals. This information is used to predict the underlying anisotropy of the region under the probe. Tissue measurements clearly demonstrate the expected higher anisotropy of muscle tissue compared to liver tissue and spectral changes.

  17. Laser-induced nuclear orientation and gamma anisotropy in sodium

    International Nuclear Information System (INIS)

    The use of laser optical pumping to induce nuclear orientation in several isotopes and one isomer of atomic sodium vapor is described. Essentially complete nuclear polarization, P > 90%, has been achieved in stable 23Na when pumping with modest laser intensities (I approx. = 10 mW/cm2). The volume of the sample cell was approximately 10 cc, and was filled with a sodium density of about 10'' atoms/cc. Complete coverage of the Doppler distribution was accomplished with the use of trace amounts (less than or equal to 1 torr) of argon buffer gas to induce velocity changing collisions. A theoretical model which accurately predicts the amount of polarization is developed. The orientation of nuclei which are unstable to gamma decay can manifest itself in anisotropic gamma ray emission. This anisotropy can be used to measure isotope and isomer shifts, from which nuclear properties can be derived. Gamma anisotropy was observed in two systems, 22Na and /sup 24m/Na. From the observed anisotropy in /sup 24m/Na, a negative sign for the g factor is determined. Values are derived for the magnetic moment, μ = 2.56 +- 0.64 nm, and the isomer shift, deltaν/sub 24m/ = 288 +- 191 MHz (D1 line). A model is described which relates various laser and fubber gas parameters to the observed gamma anisotropy lineshape. This model facilitates the extraction of physical parameters from knowledge of the laser frequency at which the anisotropy is a maximum

  18. Axisymmetric equilibria with pressure anisotropy and plasma flow

    Science.gov (United States)

    Evangelias, A.; Throumoulopoulos, G. N.

    2016-04-01

    A generalised Grad-Shafranov equation that governs the equilibrium of an axisymmetric toroidal plasma with anisotropic pressure and incompressible flow of arbitrary direction is derived. This equation includes six free surface functions and recovers known Grad-Shafranov-like equations in the literature as well as the usual static, isotropic one. The form of the generalised equation indicates that pressure anisotropy and flow act additively on equilibrium. In addition, two sets of analytical solutions, an extended Solovev one with a plasma reaching the separatrix and an extended Hernegger-Maschke one for a plasma surrounded by a fixed boundary possessing an X-point, are constructed, particularly in relevance to the ITER and NSTX tokamaks. Furthermore, the impacts both of pressure anisotropy and plasma flow on these equilibria are examined. It turns out that depending on the maximum value and the shape of an anisotropy function, the anisotropy can act either paramagnetically or diamagnetically. Also, in most of the cases considered both the anisotropy and the flow have stronger effects on NSTX equilibria than on ITER ones.

  19. Scaling of coercivity in a 3d random anisotropy model

    International Nuclear Information System (INIS)

    The random-anisotropy Heisenberg model is numerically studied on lattices containing over ten million spins. The study is focused on hysteresis and metastability due to topological defects, and is relevant to magnetic properties of amorphous and sintered magnets. We are interested in the limit when ferromagnetic correlations extend beyond the size of the grain inside which the magnetic anisotropy axes are correlated. In that limit the coercive field computed numerically roughly scales as the fourth power of the random anisotropy strength and as the sixth power of the grain size. Theoretical arguments are presented that provide an explanation of numerical results. Our findings should be helpful for designing amorphous and nanosintered materials with desired magnetic properties. - Highlights: • We study the random-anisotropy model on lattices containing up to ten million spins. • Irreversible behavior due to topological defects (hedgehogs) is elucidated. • Hysteresis loop area scales as the fourth power of the random anisotropy strength. • In nanosintered magnets the coercivity scales as the six power of the grain size

  20. Anisotropies in the HI gas distribution toward 3C196

    CERN Document Server

    Kalberla, P M W

    2016-01-01

    The local Galactic HI gas was found to contain cold neutral medium (CNM) filaments that are aligned with polarized dust emission. These filaments appear to be dominated by the magnetic field and in this case turbulence is expected to show distinct anisotropies. We use the Galactic Effelsberg--Bonn HI Survey (EBHIS) to derive 2D turbulence spectra for the HI distribution in direction to 3C196 and two more comparison fields. Prior to Fourier transform we apply a rotational symmetric 50% Tukey window to apodize the data. We derive average as well as position angle dependent power spectra. Anisotropies in the power distribution are defined as the ratio of the spectral power in orthogonal directions. We find strong anisotropies. For a narrow range in position angle, in direction perpendicular to the filaments and the magnetic field, the spectral power is on average more than an order of magnitude larger than parallel. In the most extreme case the anisotropy reaches locally a factor of 130. Anisotropies increase on...

  1. Axisymmetric equilibria with pressure anisotropy and plasma flow

    Science.gov (United States)

    Throumoulopoulos, George; Evangelias, Achilleas

    2015-11-01

    A generalised Grad-Shafranov equation that governs the equilibrium of an axisymmetric toroidal plasma with anisotropic pressure and incompressible flow of arbitrary direction is derived. This equation includes six free surface functions and recovers known Grad-Shafranov-like equations in the literature as well as the usual static, isotropic one. The form of the generalised equation indicates that pressure anisotropy and flow act additively on equilibrium. In addition, two sets of analytical solutions, an extended Solovev one with a free boundary and an extended Hernegger-Maschke one for a plasma surrounded by a fixed boundary possessing an X-point, are constructed, particularly in relevance to the ITER and NSTX tokamaks. Furthermore, the impacts both of pressure anisotropy and plasma flow on these equilibria are examined. It turns out that depending on the maximum value and the shape of an anisotropy function, the anisotropy can act either paramagnetically or diamagnetically. Also, in most of the cases considered both the anisotropy and the flow have stronger effects on NSTX equilibria than on ITER ones. This work has been carried out within the framework of the EUROfusion Consortium and has received funding from (a) the National Programme for the Controlled Thermonuclear Fusion, Hellenic Republic, (b) Euratom research and training programme 2014-2018.

  2. Performance of ERNE in particle flux anisotropy measurement

    Directory of Open Access Journals (Sweden)

    E. Riihonen

    Full Text Available The HED particle detector of the ERNE experiment to be flown on the SOHO spacecraft is unique compared to the earlier space-born detectors in its high directional resolution (better than 2°, depending on the track inclination. Despite the fixed view cone due to the three-axis stabilization of the spacecraft, the good angular and temporal resolution of the detector provides a new kind of opportunity for monitoring in detail the development of the anisotropies pertaining, for example, to the onset of SEP events, or passage of shock fronts related to gradual events. In order to optimize the measurement parameters, we have made a preflight simulation study of the HED anisotropy measurement capabilities. The purpose was to prove the feasibility of the selected measurement method and find the physical limits for the HED anisotropy detection. The results show HED to be capable of detecting both strong anisotropies related to impulsive events, and smoother anisotropies associated with gradual events.

  3. Phenomenological description of anisotropy effects in some ferromagnetic superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Shopova, Diana V., E-mail: sho@issp.bas.bg [TCCM Research Group, Institute of Solid State Physics, Bulgarian Academy of Sciences, BG-1784 Sofia (Bulgaria); Todorov, Michail D. [Department of Applied Mathematics and Computer Science, Technical University of Sofia, 1000 Sofia (Bulgaria)

    2015-07-03

    We study phenomenologically the role of anisotropy in ferromagnetic superconductors UGe{sub 2}, URhGe, and UCoGe for the description of their phase diagrams. We use the Ginzburg–Landau free energy in its uniform form as we will consider only spatially independent solutions. This is an expansion of previously derived results where the effect of Cooper-pair and crystal anisotropies is not taken into account. The three compounds are separately discussed with the special stress on UGe{sub 2}. The main effect comes from the strong uniaxial anisotropy of magnetization while the anisotropy of Cooper pairs and crystal anisotropy only slightly change the phase diagram in the vicinity of Curie temperature. The limitations of this approach are also discussed. - Highlights: • Anisotropic Landau energy for description of ferromagnetic superconductors is proposed. • Meissner phases are described with their existence and stability conditions. • The application of the model to UGe{sub 2} is discussed. • The limitations to apply the model for description of experimental data are explained.

  4. 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.

  5. Anisotropic magnetorestistance and magnetic anisotropy of Heusler compound thin films

    Energy Technology Data Exchange (ETDEWEB)

    Althammer, Matthias; Krupp, Alexander T.; Czeschka, Franz D.; Opel, Matthias; Gross, Rudolf; Goennenwein, Sebastian T.B. [Walther-Meissner-Institut, Bayerische Akademie der Wissenschaften, Garching (Germany); Imort, Inga-Mareen; Reiss, Guenter; Thomas, Andy [Fakultaet fuer Physik, Universitaet Bielefeld, Bielefeld (Germany)

    2011-07-01

    Magnetic anisotropy is of fundamental importance in ferromagnets, as it strongly influences their properties. Using anisotropic magnetoresistance (AMR) measurements, we investigate the magnetic anisotropy of the ferromagnetic Heusler compound Co{sub 2}FeAl. Thin Co{sub 2}FeAl films grown on (001)-oriented MgO substrate were patterned into Hall-bar mesa structures via optical lithography and etching. To quantify the magnetic anisotropy, we recorded the angle dependent magnetoresistance (ADMR), i.e., the AMR as a function of magnetic field orientation for different magnetic field magnitudes H. From the ADMR data taken at high vertical stroke H vertical stroke, the resistivity coefficients are obtained. The magnetic anisotropy is then extracted from ADMR taken at lower vertical stroke H vertical stroke. We will quantitatively compare the resistivity coefficients and the magnetic anisotropy in Co{sub 2}FeAl thin films with thicknesses of 20 nm, 50 nm, 80 nm, 100 nm, as a function of temperature from 5 K to 350 K.

  6. Phenomenological description of anisotropy effects in some ferromagnetic superconductors

    International Nuclear Information System (INIS)

    We study phenomenologically the role of anisotropy in ferromagnetic superconductors UGe2, URhGe, and UCoGe for the description of their phase diagrams. We use the Ginzburg–Landau free energy in its uniform form as we will consider only spatially independent solutions. This is an expansion of previously derived results where the effect of Cooper-pair and crystal anisotropies is not taken into account. The three compounds are separately discussed with the special stress on UGe2. The main effect comes from the strong uniaxial anisotropy of magnetization while the anisotropy of Cooper pairs and crystal anisotropy only slightly change the phase diagram in the vicinity of Curie temperature. The limitations of this approach are also discussed. - Highlights: • Anisotropic Landau energy for description of ferromagnetic superconductors is proposed. • Meissner phases are described with their existence and stability conditions. • The application of the model to UGe2 is discussed. • The limitations to apply the model for description of experimental data are explained

  7. Ice-Borehole Probe

    Science.gov (United States)

    Behar, Alberto; Carsey, Frank; Lane, Arthur; Engelhardt, Herman

    2006-01-01

    An instrumentation system has been developed for studying interactions between a glacier or ice sheet and the underlying rock and/or soil. Prior borehole imaging systems have been used in well-drilling and mineral-exploration applications and for studying relatively thin valley glaciers, but have not been used for studying thick ice sheets like those of Antarctica. The system includes a cylindrical imaging probe that is lowered into a hole that has been bored through the ice to the ice/bedrock interface by use of an established hot-water-jet technique. The images acquired by the cameras yield information on the movement of the ice relative to the bedrock and on visible features of the lower structure of the ice sheet, including ice layers formed at different times, bubbles, and mineralogical inclusions. At the time of reporting the information for this article, the system was just deployed in two boreholes on the Amery ice shelf in East Antarctica and after successful 2000 2001 deployments in 4 boreholes at Ice Stream C, West Antarctica, and in 2002 at Black Rapids Glacier, Alaska. The probe is designed to operate at temperatures from 40 to +40 C and to withstand the cold, wet, high-pressure [130-atm (13.20-MPa)] environment at the bottom of a water-filled borehole in ice as deep as 1.6 km. A current version is being outfitted to service 2.4-km-deep boreholes at the Rutford Ice Stream in West Antarctica. The probe (see figure) contains a sidelooking charge-coupled-device (CCD) camera that generates both a real-time analog video signal and a sequence of still-image data, and contains a digital videotape recorder. The probe also contains a downward-looking CCD analog video camera, plus halogen lamps to illuminate the fields of view of both cameras. The analog video outputs of the cameras are converted to optical signals that are transmitted to a surface station via optical fibers in a cable. Electric power is supplied to the probe through wires in the cable at a

  8. Pressure measuring probe

    Science.gov (United States)

    Ashby, George C., Jr. (Inventor)

    1988-01-01

    The invention is a probe for measuring changes in pressure in a high velocity fluid stream over and adjacent to the surface of an object. The probe is formed of an exterior housing having a closed pressure chamber in which a piezoelectric pressure transducer is mounted. An open connector tube having a probe tip passes a portion of the fluid stream into the closed pressure chamber; any change of pressure within, which requires a settling-time to appear in the closed pressure chamber, is inversely proportional to the cross-sectional area of the connector tube. A cooling chamber formed around the pressure chamber is connected to a source of cooling fluid by means of inlet and outlet tubes.

  9. Multispectral imaging probe

    Science.gov (United States)

    Sandison, David R.; Platzbecker, Mark R.; Descour, Michael R.; Armour, David L.; Craig, Marcus J.; Richards-Kortum, Rebecca

    1999-01-01

    A multispectral imaging probe delivers a range of wavelengths of excitation light to a target and collects a range of expressed light wavelengths. The multispectral imaging probe is adapted for mobile use and use in confined spaces, and is sealed against the effects of hostile environments. The multispectral imaging probe comprises a housing that defines a sealed volume that is substantially sealed from the surrounding environment. A beam splitting device mounts within the sealed volume. Excitation light is directed to the beam splitting device, which directs the excitation light to a target. Expressed light from the target reaches the beam splitting device along a path coaxial with the path traveled by the excitation light from the beam splitting device to the target. The beam splitting device directs expressed light to a collection subsystem for delivery to a detector.

  10. Asymmetric velocity anisotropies in remnants of collisionless mergers

    CERN Document Server

    Sparre, Martin

    2012-01-01

    Dark matter haloes in cosmological N-body simulations are affected by processes such as mergers, accretion and the gravitational interaction with baryonic matter. In typical analyses of dark matter haloes, the velocity distributions are assumed to be spherically symmetric. The validity of this assumption has, however, not been explicitly tested. We derive properties of particles in cones parallel or perpendicular to the collision axis of merger remnants. We find that the velocity anisotropy, which describes differences in the radial and tangential velocity dispersion, has a strong dependence on direction. The finding that the direction-dependence of the velocity anisotropy of a halo depends on the merger history, explain why a large diversity is seen in the velocity anisotropy profiles in the outer parts of high-resolution simulations of cosmological haloes.

  11. Interplay between anisotropy and spatial dispersion in metamaterial waveguide

    CERN Document Server

    Koshelev, Kirill L

    2016-01-01

    We analyze spectrum of waveguide modes of an arbitrary uniaxial anisotropic metamaterial slab with non-local electromagnetic response whose permittivity tensor could be described within Drude approximation. Spatial dispersion was introduced within the hydrodynamical model. Both anisotropy and spatial dispersion were considered as perturbations. This helps to distinguish their effect on the spectrum of the slab and to analyze lifting of the degeneracy of eigenmodes at plasma frequency in detail. Spatial dispersion is shown to result in break of the singularity in the den- sity of optical states in the hyperbolic regime and in suppression of negative dispersion induced by anisotropy. Mutual effect of spatial dispersion and anisotropy can bring light to a complete stop at certain frequencies.

  12. Deformed flux tubes produce azimuthal anisotropy in heavy ion collisions

    Science.gov (United States)

    Pirner, H. J.; Reygers, K.; Kopeliovich, B. Z.

    2016-03-01

    We investigate the azimuthal anisotropy v2 of particle production in nucleus-nucleus collisions in the maximum entropy approach. This necessitates two new phenomenological input parameters δ and λ2 compared with integrated multiplicity distributions. The parameter δ describes the deformation of a flux tube and can be theoretically calculated in a bag model with a bag constant which depends on the density of surrounding flux tubes. The parameter λ2 defines the anisotropy of the particle distribution in momentum space and can be connected to δ via the uncertainty relation. In this framework we compute the anisotropy v2 as a function of centrality, transverse momentum, and rapidity in qualitative agreement with Large Hadron Collider data.

  13. Jc anisotropy in 122 and 1111 pnictide thin films

    International Nuclear Information System (INIS)

    We have successfully grown epitaxial, superconducting films in two families of iron pnictides, Ba(Fe1-xCox)2As2 (122) and LaFeAs(O1-x,Fx) (1111). Detailed investigations of their critical current density Jc with respect to temperature as well as both the applied magnetic field magnitude and orientation are shown in this contribution. Both films grow very clean and without observable correlated defects parallel to the c-axis, as confirmed by TEM. This is also reflected in the absence of a c-axis peak in Jc(θ). In contrast to cuprate high-Tc superconductors such as YBCO or even Bi2223, the pnictides have very low anisotropies in their Jc(θ) behaviour as well as in their characteristic and critical fields, such as Hirr and Hc2. Both families show the same anisotropy behaviour, 122 having slightly lower anisotropies.

  14. Optical activity of chitosan films with induced anisotropy

    Science.gov (United States)

    Gegel, Natalia O.; Shipovskaya, Anna B.

    2016-04-01

    The optical anisotropy and optical activity of salt and basic chitosan films, both initial and modified in formic acid vapor were studied. The modification of such films was found to be accompanied by induced time-stable optical anisotropy, by varying the values of specific optical rotation [α] and an inversion of the sign of [α]. The angular dependences (indicatrices) of the specific optical rotation of films on the orientation angle of the sample relative to the direction of the polarization vector of the incident light beam in a plane perpendicular to the beam were obtained. The indicatrices of the initial chitosan films have an almost symmetrical character while those of the films modified in formic acid vapor are irregular. It is concluded of the formation of a vitrified cholesteric mesophase in the chitosan films with induced optical anisotropy.

  15. Finite-size anisotropy in statistically uniform porous media

    CERN Document Server

    Koza, Zbigniew; Khalili, Arzhang

    2009-01-01

    Anisotropy of the permeability tensor in statistically uniform porous media of sizes used in typical computer simulations is studied. Although such systems are assumed to be isotropic by default, we show that de facto their anisotropic permeability can give rise to significant changes of transport parameters such as permeability and tortuosity. The main parameter controlling the anisotropy is $a/L$, being the ratio of the obstacle to system size. Distribution of the angle $\\alpha$ between the external force and the volumetric fluid stream is found to be approximately normal, and the standard deviation of $\\alpha$ is found to decay with the system size as $(a/L)^{d/2}$, where $d$ is the space dimensionality. These properties can be used to estimate both anisotropy-related statistical errors in large-scale simulations and the size of the representative elementary volume.

  16. Anisotropy of radiation emitted from planar wire arrays

    Energy Technology Data Exchange (ETDEWEB)

    Kantsyrev, V. L.; Esaulov, A. A.; Safronova, A. S.; Williamson, K. M.; Osborne, G. C.; Shrestha, I. K.; Weller, M. E.; Shlyaptseva, V. V. [Department of Physics, University of Nevada, Reno, Nevada 89557 (United States); Chuvatin, A. S. [Laboratorie de Physique des Plasmas, Ecole Polytechnique, 91128 Palaiseau (France); Rudakov, L. I. [Icarus Research, Inc., P. O. Box 30780, Bethesda, Maryland 20824-0780 (United States); Velikovich, A. [Naval Research Laboratory, Plasma Physics Division, Washington, DC 20375 (United States)

    2013-07-15

    The planar wire array (PWA) is a promising load for new multi-source inertial confinement fusion (ICF) hohlraums [B. Jones et al., Phys. Rev. Lett. 104, 125001 (2010)]. The hohlraum radiation symmetry is an important issue for ICF. It was found that extreme ultraviolet and sub-keV photon emission from PWAs may have considerable anisotropy in the load azimuthal plane. This experimental result is obtained on the UNR 1–1.7 MA Zebra generator. The time-dependent anisotropy effect is detected. This feature is studied in 2D numerical simulations and can be explained by initial anisotropy of implosion of those non-cylindrical loads radiating essentially as surface sources in sub-keV quanta and also by radiation absorption in cold magnetized plasma tails forming in the direction of magnetic compression.

  17. SIMULTANEOUS MEASUREMENT OF CIRCULAR DICHROISM AND FLUORESCENCE POLARIZATION ANISOTROPY.

    Energy Technology Data Exchange (ETDEWEB)

    SUTHERLAND,J.C.

    2002-01-19

    Circular dichroism and fluorescence polarization anisotropy are important tools for characterizing biomolecular systems. Both are used extensively in kinetic experiments involving stopped- or continuous flow systems as well as titrations and steady-state spectroscopy. This paper presents the theory for determining circular dichroism and fluorescence polarization anisotropy simultaneously, thus insuring the two parameters are recorded under exactly the same conditions and at exactly the same time in kinetic experiments. The approach to measuring circular dichroism is that used in almost all conventional dichrographs. Two arrangements for measuring fluorescence polarization anisotropy are described. One uses a single fluorescence detector and signal processing with a lock-in amplifier that is similar to the measurement of circular dichroism. The second approach uses classic ''T'' format detection optics, and thus can be used with conventional photon-counting detection electronics. Simple extensions permit the simultaneous measurement of the absorption and excitation intensity corrected fluorescence intensity.

  18. Polarization of thermal bremsstrahlung emission due to electron pressure anisotropy

    CERN Document Server

    Komarov, S; Churazov, E; Schekochihin, A

    2016-01-01

    Astrophysical plasmas are typically magnetized, with the Larmor radii of the charged particles many orders of magnitude smaller than their collisional mean free paths. The fundamental properties of such plasmas, e.g., conduction and viscosity, may depend on the instabilities driven by the anisotropy of the particle distribution functions and operating at scales comparable to the Larmor scales. We discuss a possibility that the pressure anisotropy of thermal electrons could produce polarization of thermal bremsstrahlung emission. In particular, we consider coherent large-scale motions in galaxy clusters to estimate the level of anisotropy driven by stretching of the magnetic-field lines by plasma flow and by heat fluxes associated with thermal gradients. Our estimate of the degree of polarization is $\\sim 0.1 \\%$ at energies $\\gtrsim kT$. While this value is too low for the forthcoming generation of X-ray polarimeters, it is potentially an important proxy for the processes taking place at extremely small scale...

  19. Irreversible magnetic processes under biaxial and uniaxial magnetic anisotropies

    Directory of Open Access Journals (Sweden)

    S. Pokharel

    2016-05-01

    Full Text Available Irreversible magnetic processes have been investigated in magnetic systems with two different anisotropy symmetries (uniaxial and biaxial through angular measurement of the switching field, the irreversible susceptibility and the magnetic viscosity. These two systems consist of two-dimensional cobalt ferrite hetero-structures epitaxially grown on (100 and (110 MgO substrate. It is found that for uniaxial anisotropy the irreversible characteristics of the magnetization are large and display a strong angular dependence, which exhibits its maximum at the easy axis and drops quickly to vanish at the hard axis. However, for biaxial anisotropy the magnetization irreversible characteristics are considerably reduced and are less sensitive to the field angle.

  20. Cosmic Ray Small Scale Anisotropies and Local Turbulent Magnetic Fields

    CERN Document Server

    López-Barquero, Vanessa; Xu, S; Desiati, P; Lazarian, A

    2015-01-01

    Cosmic ray anisotropy is observed in a wide energy range and at different angular scales by a variety of experiments. However, a comprehensive and satisfactory explanation has been elusive for over a decade now. The arrival distribution of cosmic rays on 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 angular scale structure could be an effect of non diffusive propagation of cosmic rays in perturbed magnetic fields. In particular, a possible explanation of the observed small scale anisotropy observed at TeV energy scale, may come from the effect of particle scattering in turbulent magnetized plasmas. We perform numerical integration of test particle trajectories in low-$\\beta$ compressible mag...

  1. Stress-induced permeability anisotropy in fractured reservoir

    Energy Technology Data Exchange (ETDEWEB)

    Du, J.; Wong, R.C.K. [Calgary Univ., AB (Canada)

    2002-07-01

    The approach generally used to analyze the anisotropy of a heterogeneous, naturally fractured reservoirs was examined to verify if the approach is appropriate. Most reservoir simulations account for permeability anisotropy in fractured reservoirs through 3 principal permeabilities and 3 mutually orthogonal principal axes. It is demonstrated that the deformation of the fractures from changes in stress could result in an offset of the permeability tensor. This would result in an error in well interpretation because the conventional simple anisotropy model does not consider the cross permeability effect. The stress displacement behaviour of the fracture was also examined in this study through a non-linear model that can be used to describe the closure process of the fracture under varying stresses. The authors propose a comprehensive coupled model for geomechanical reservoir analysis. The advantage of the newly proposed model is that it takes into account the full permeability tensor and non-linear deformation properties of the fracture. 10 refs., 8 figs.

  2. 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

  3. Enhancement of rotatable anisotropy in ferrite doped FeNi thin film with oblique sputtering

    Science.gov (United States)

    Zhou, Cai; Jiang, Changjun; Zhao, Zhong

    2015-07-01

    Rotatable anisotropy of stripe domain (SD) was investigated in a ferrite doped FeNi thin film with different oblique angles. Rotation of SD under an in-plane magnetic field was observed by magnetic force microscopy, suggesting the existence of rotatable anisotropy. A rotatable anisotropy field Hrot was derived from the fitting curves of the in-plane resonance field versus the angle between the orientation of easy axis and applied field. As the oblique angle increases, an increase of Hrot from 305 Oe to 468 Oe was observed and the perpendicular anisotropy increased as well, indicating a correlation between rotatable anisotropy and perpendicular anisotropy.

  4. Three dimensional solar anisotropy of galactic cosmic rays near the recent solar minimum 23/24

    CERN Document Server

    Modzelewska, R

    2015-01-01

    Three dimensional (3D) galactic cosmic ray (GCR) anisotropy has been studied for 2006- 2012. The GCR anisotropy, both in the ecliptic plane and in polar direction, were obtained based on the neutron monitors (NMs) and Nagoya muon telescopes (MT) data. We analyze two dimensional (2D) GCR anisotropy in the ecliptic plane and north-south anisotropy normal to the ecliptic plane. We reveal quasi-periodicities - the annual and 27-days waves in the GCR anisotropy in 2006-2012. We investigate the relationship of the 27-day variation of the GCR anisotropy in the ecliptic plane and in the polar direction with the parameters of solar activity and solar wind.

  5. 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

  6. Seismic anisotropy in granite at the Underground Research Laboratory, Manitoba

    International Nuclear Information System (INIS)

    The Shear-Wave Experiment at Atomic Energy of Canada Limited's Underground Research Laboratory was probably the first controlled-source shear-wave survey in a mine environment. Taking place in conjunction with the excavation of the Mine-by test tunnel at 420 m depth, the shear-wave experiment was designed to measure the in situ anisotropy of the rockmass and to use shear waves to observe excavation effects using the greatest variety of raypath directions of any in situ shear-wave survey to date. Inversion of the shear-wave polarizations shows that the anisotropy of the in situ rockmass is consistent with hexagonal symmetry with an approximate fabric orientation of strike 023degree and dip 35degree. The in situ anisotropy is probably due to microcracks with orientations governed by the in situ stress field and to mineral alignment within the weak gneissic layering. However, there is no unique interpretation as to the cause of the in situ anisotropy as the fabric orientation agrees approximately with both the orientation expected from extensive-dilatancy anisotropy and that of the gneissic layering. Eight raypaths with shear waves propagating wholly or almost wholly through granodiorite, rather than granite, do not show the expected shear-wave splitting and indicate a lower in situ anisotropy, which may be due to the finer grain size and/or the absence of gneissic layering within the granodiorite. These results suggest that shear waves may be used to determine crack and mineral orientations and for remote monitoring of a rockmass. This has potential applications in mining and waste monitoring

  7. Probing The New Cosmology

    CERN Document Server

    Zentner, A R

    2003-01-01

    Improvements in observational techniques have transformed cosmology into a field inundated with ever-expanding, high-quality data sets and driven cosmology toward a standard model where the classic cosmological parameters are accurately measured. I briefly discuss some of the methods used to determine cosmological parameters, particularly primordial nucleosynthesis, the magnitude- redshift relation of supernovae, and cosmic microwave background anisotropy. I demonstrate how cosmological data can be used to complement particle physics and constrain extensions to the Standard Model. Specifically, I present bounds on light particle species and the properties of unstable, weakly-interacting, massive particles. Despite the myriad successes of the emerging standard cosmological model, unanswered questions linger. Numerical simulations of structure formation predict galactic central densities that are considerably higher than observed. They also reveal hundreds of satellites orbiting Milky Way-like galaxies while th...

  8. Perpendicular Magnetic Anisotropy in CoFeB/Pd Bilayers

    OpenAIRE

    COEY, JOHN; FOWLEY, CIARAN; OGUZ, KAAN; Rode, Karsten; Kurt, Huseyin

    2010-01-01

    PUBLISHED Perpendicular magnetic anisotropy is observed in ultrathin (0.6 nm) amorphous Co40Fe40B20 when sputtered on an MgO (001) buffer layer and capped with Pd. The layers are superparamagnetic with a blocking temperature of similar to 230 K, below which they show an exponential temperature dependence of coercivity. Perpendicular magnetic anisotropy is observed in the as-deposited state and the mechanism is different from that of CoFeB/Pt, which requires postannealing. These ultrathin l...

  9. Depth dependence of anisotropy of Earth's inner core

    OpenAIRE

    Song, Xiaodong; Helmberger, Don V.

    1995-01-01

    Both body wave (PKP) travel times (Creager, 1992; Song and Helmberger, 1993a; McSweeney and Creager, 1993; Shearer, 1994) and fits to the splitting of core modes (Tromp, 1993) show general agreement that the top 300 km of inner core is very anisotropic. The anisotropy displays axial symmetry around the Earth's spin axis, with the polar direction 3% faster than the equatorial direction. One key problem now is the depth dependence of the inner core anisotropy. Here we extend our polar path stud...

  10. Anisotropy of charge and spin motion in perylene hexafluoroarsenate salts

    Energy Technology Data Exchange (ETDEWEB)

    Warth, A; Jauregui, D Saez de; Dormann, E [Physikalisches Institut, Universitaet Karlsruhe (Thailand), D-76128 Karlsruhe, Germany

    2005-08-03

    Conduction electron spin echo attenuation in well defined magnetic field gradients provides more accurate values of the anisotropy of electron spin motion than microwave conductivity measurements. The electron spin diffusion coefficient for motion along the perylene (PE) radical cation stack, D{sub parallel}(T), in the PE hexafluoroarsenate salt is influenced temperature dependently by perpendicular-to-stack motion and reflects the varying average unrestricted chain length, l{sub parallel}bar(T). The anisotropy of D{sub parallel}(T):D{sub perpendicular}(T) is larger than 7300:1 at 250 K.

  11. Anisotropy of charge and spin motion in perylene hexafluoroarsenate salts

    International Nuclear Information System (INIS)

    Conduction electron spin echo attenuation in well defined magnetic field gradients provides more accurate values of the anisotropy of electron spin motion than microwave conductivity measurements. The electron spin diffusion coefficient for motion along the perylene (PE) radical cation stack, Dparallel(T), in the PE hexafluoroarsenate salt is influenced temperature dependently by perpendicular-to-stack motion and reflects the varying average unrestricted chain length, lparallelbar(T). The anisotropy of Dparallel(T):Dperpendicular(T) is larger than 7300:1 at 250 K

  12. The magnetocaloric effect: The role of magnetic anisotropy

    Energy Technology Data Exchange (ETDEWEB)

    Bennett, L.H.; McMichael, R.D.; Shull, R.D.; Swartzendruber, L.J. (NIST, Gaithersburg, Maryland 20899 (United States)); Watson, R.E. (Brookhaven National Laboratory, Upton, New York 11973 (United States))

    1993-05-15

    In a ferromagnet, the magnetic entropy change induced by the application of a magnetic field is greatest in the temperature regime near the Curie point. In the paramagnetic temperature regime, the magnitude of the magnetocaloric effect is expected to rise monotonically with the size of the individual moments that make up the material. The magnetic properties of such materials are relevant to devices employing magnetic refrigeration. One aspect of the problem, namely the impact of uniaxial magnetic anisotropy on the magnetocaloric effect, is explored. The results of Monte Carlo simulations for classical Heisenberg ferromagnets on a fcc lattice with anisotropy are presented.

  13. The magnetocaloric effect: The role of magnetic anisotropy

    International Nuclear Information System (INIS)

    In a ferromagnet, the magnetic entropy change induced by the application of a magnetic field is greatest in the temperature regime near the Curie point. In the paramagnetic temperature regime, the magnitude of the magnetocaloric effect is expected to rise monotonically with the size of the individual moments that make up the material. The magnetic properties of such materials are relevant to devices employing magnetic refrigeration. One aspect of the problem, namely the impact of uniaxial magnetic anisotropy on the magnetocaloric effect, is explored. The results of Monte Carlo simulations for classical Heisenberg ferromagnets on a fcc lattice with anisotropy are presented

  14. Fabrication of epitaxial Fe nanodot arrays and anisotropy engineering

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, H. M.; Kim, S. H.; Lee, H. S.; Lee, J. [Yonsei University, Seoul (Korea, Republic of)

    2010-04-15

    Arrays of Fe nanodots were fabricated from an epitaxial Fe (20 nm) film on Cu (001)/Si(001) by using laser interference lithography and chemical wet etching. The nanodots were aligned parallel to the two magnetic hard directions of the film and were arranged on rectangular lattices of different periods in order to engineer the magnetic anisotropy of the system by using the shape of array. As the separation between dots along one direction decrease from 550 nm to 150 nm, the dipole interaction effect became strong, and finally a uniaxial magnetic anisotropy were realized.

  15. Dielectric and magnetic anisotropy of a nematic ytterbium complex

    International Nuclear Information System (INIS)

    The sign and the magnitude of the dielectric anisotropy of an ytterbium-based paramagnetic nematic liquid crystal complex, namely, tris[1-(4-(4-propylcyclohexyl)phenyl)octane-1,3-dione]-[5,5'-di (heptadecile)-2,2'-bipyridine]ytterbium, are determined. The temperature dependence of the permittivity components of the complex is obtained in the temperature range of a nematic phase. The sign of the anisotropy of the magnetic susceptibility of this compound is experimentally determined

  16. Dielectric and magnetic anisotropy of a nematic ytterbium complex

    Energy Technology Data Exchange (ETDEWEB)

    Dobrun, L. A., E-mail: l.dobrun@spbu.ru; Sakhatskii, A. S.; Kovshik, A. P.; Ryumtsev, E. I.; Kolomiets, I. P. [St. Petersburg State University (Russian Federation); Knyazev, A. A.; Galyametdinov, Yu. G. [Kazan National Research Technological University (Russian Federation)

    2015-05-15

    The sign and the magnitude of the dielectric anisotropy of an ytterbium-based paramagnetic nematic liquid crystal complex, namely, tris[1-(4-(4-propylcyclohexyl)phenyl)octane-1,3-dione]-[5,5'-di (heptadecile)-2,2'-bipyridine]ytterbium, are determined. The temperature dependence of the permittivity components of the complex is obtained in the temperature range of a nematic phase. The sign of the anisotropy of the magnetic susceptibility of this compound is experimentally determined.

  17. Influence of temperature on the Zircaloy-4 plastic anisotropy

    International Nuclear Information System (INIS)

    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

  18. Creep anisotropy of recrystallized Zircaloy-4 TREX using impression tests

    International Nuclear Information System (INIS)

    It is well known that zirconium alloys develop preferred orientation (texture) during forming processes. This arises from the anisotropy of hcp single crystal Zr and from the limited number of operating slip systems. These measurements were complemented by calculations of R and P based on lower bound plasticity models (Murty and Adams, 1985, Murty et al., 1985) using Crystallite Orientation Distribution Functions [CODFs] generated from X-ray crystallographic techniques. This two-fold approach leads to a comparison between the creep anisotropy measured by the impression test and that derived from the plasticity model. (orig./GL)

  19. Group constant estimation and account for scattering anisotropy

    International Nuclear Information System (INIS)

    Suggested approach to estimation of group constants lies in preservation of characteristics of neutron flux which is formed after interaction with nucleus-target in exact and approximate descriptions of scattering anisotropy. Requirement of preserving a series of corresponding harmonics of resulting secondary flux, multiplying properties of substance, matrix elements of intergroup approaches and energy release leads to formulas of generalized transport approximation for scattering anisotropy. Introduction of limitations on the value of cross section correction leads to consistent values of probability of intergroup transitions. 6 refs

  20. Small-angle anisotropies in the CMBR from active sources

    CERN Document Server

    Battye, R A

    1997-01-01

    We consider the effects of photon diffusion on the small-angle microwave background anisotropies due to active source models. We find that fluctuations created just before the time of last scattering allow anisotropy to be created on scales much smaller than allowed by standard Silk damping. Using simple models for string and texture structure functions as examples, we illustrate the differences in the angular power spectrum at scales of order a few arcminutes. In particular, we find that the Doppler peak heights are modified by 10-50% and the small-angle fall-off is power law rather than exponential.

  1. Re-entrant behaviour in a random anisotropy magnet

    International Nuclear Information System (INIS)

    Amorphous Gd7-xDyxNi3 is a model random anisotropy system in which the exchange J can be varied whilst maintaining a constant single ion anisotropy D. Investigation of the magnetic phase diagram as x, and hence D/J, increases reveals a re-entrant transition from correlated speromagnet to speromagnet for x4 the paramagnetic-speromagnetic transition is direct. A multicritical point is observed at x=4, at which the exponent γ increases suddenly from 1.35 to 2. ((orig.))

  2. Random-anisotropy Blume-Emery-Griffiths model

    Science.gov (United States)

    Maritan, Amos; Cieplak, Marek; Swift, Michael R.; Toigo, Flavio; Banavar, Jayanth R.

    1992-01-01

    The results are described of studies of a random-anisotropy Blume-Emery-Griffiths spin-1 Ising model using mean-field theory, transfer-matrix calculations, and position-space renormalization-group calculations. The interplay between the quenched randomness of the anisotropy and the annealed disorder introduced by the spin-1 model leads to a rich phase diagram with a variety of phase transitions and reentrant behavior. The results may be relevant to the study of the phase separation of He-3 - He-4 mixtures in porous media in the vicinity of the superfluid transition.

  3. Anisotropy in layered half-metallic Heusler alloy superlattices

    Energy Technology Data Exchange (ETDEWEB)

    Azadani, Javad G.; Munira, Kamaram; Sivakumar, Chockalingam; Butler, William H. [Center for Materials for Information Technology, University of Alabama, Tuscaloosa, Alabama 35487 (United States); Department of Physics and Astronomy, University of Alabama, Tuscaloosa, Alabama 35487 (United States); Romero, Jonathon [Department of Physics and Astronomy, University of Alabama, Tuscaloosa, Alabama 35487 (United States); Ma, Jianhua; Ghosh, Avik W. [Department of Electrical and Computer Engineering, University of Virginia, Charlottesville, Virginia 22904 (United States)

    2016-01-28

    We show that when two Heusler alloys are layered in the [001], [110], or [111] directions for various thicknesses to form a superlattice, the Slater-Pauling rule may still be satisfied and the resulting superlattice is often half-metallic with gaps comparable to or larger than those of its constituents. In addition, uniaxial magnetocrystalline anisotropy is induced because of the differences in the electronic structure of the two Heuslers in the superlattice. Various full-full, full-half, and half-half Heusler superlattices are studied, and potential half-metallic superlattices with perpendicular magnetocrystalline anisotropy are identified.

  4. Anisotropies of Cosmic Background Radiation from a Local Collapse

    OpenAIRE

    Wu, Xiang-Ping; Fang, Li-Zhi

    1993-01-01

    We present an exact solution of the anisotropies of cosmic background radiation (CBR) from a local collapse described by a spherical over-dense region embedded in a flat universe, with the emphasis on the relationship between the dipole $(\\Delta {\\sf T}/{\\sf T})_d$ and the quadrupole $(\\Delta {\\sf T}/{\\sf T})_q$ anisotropy. This result has been used to examine the kinematic quadrupole correction $(\\Delta {\\sf T}/{\\sf T})_q=(\\Delta {\\sf T}/{\\sf T})_d^2/2$, which is usually applied to remove th...

  5. Topographical Anisotropy and Wetting of Ground Stainless Steel Surfaces

    Directory of Open Access Journals (Sweden)

    Cornelia Bellmann

    2012-12-01

    Full Text Available Microscopic and physico-chemical methods were used for a comprehensive surface characterization of different mechanically modified stainless steel surfaces. The surfaces were analyzed using high-resolution confocal microscopy, resulting in detailed information about the topographic properties. In addition, static water contact angle measurements were carried out to characterize the surface heterogeneity of the samples. The effect of morphological anisotropy on water contact angle anisotropy was investigated. The correlation between topography and wetting was studied by means of a model of wetting proposed in the present work, that allows quantifying the air volume of the interface water drop-stainless steel surface.

  6. Friction anisotropy dependence on lattice orientation of graphene

    Science.gov (United States)

    Zhang, Yu; Liu, LianQing; Xi, Ning; Wang, YueChao; Dong, ZaiLi; Wejinya, Uchechukwu C.

    2014-04-01

    The observation of friction anisotropy on graphene by friction measurement at atomic scale has been reported in this paper. Atomic-scale friction measurement revealed friction anisotropy with a periodicity of 60°, which is consistent with the hexagonal periodicity of the graphene. Both experiments and theory show that the value of the friction force is related to the graphene lattice orientation, and the friction force along armchair orientation is also larger than the one along zigzag orientation. These results will play a critical role in the use of graphene to manufacture nanoscale devices.

  7. Influence of Elastic Anisotropy on Extended Dislocation Nodes

    International Nuclear Information System (INIS)

    The interaction forces between the partial dislocations forming an extended dislocation node are calculated using elasticity theory for anisotropic media.s are carried out for nodes of screw, edge and mixed character in Ag, which has an anisotropy ratio A equal to 3, and in a hypothetic material with A = 1 and the same shear modulus as Ag. The results are compared with three previous theories using isotropic elasticity theory. As expected, in Ag the influence of anisotropy is of the same order as the uncertainty due to the dislocation core energy

  8. Anisotropy of mechanical properties of zirconium and zirconium alloys

    International Nuclear Information System (INIS)

    In studies of technological applications of zirconium to fuel elements of nuclear reactor, it was found that the use of plasticity equations for isotropic materials is not in agreement with experimental results, because of the strong anisotropy of zirconium. The present review describes recent progress on the knowledge of the influence of anisotropy on mechanical properties, after Douglass' review in 1971. The review was written to be selfconsistent, changing drastically the presentation of some of the referenced papers. It is also suggested some particular experiments to improve developments in this area

  9. Electronic nematic phase transition in the presence of anisotropy

    OpenAIRE

    Yamase, Hiroyuki

    2014-01-01

    We study the phase diagram of electronic nematic instability in the presence of xy anisotropy. While a second order transition cannot occur in this case, mean-field theory predicts that a first order transition occurs near van Hove filling and its phase boundary forms a wing structure, which we term a Griffiths wing, referring to his original work of He3-He4 mixtures. When crossing the wing, the anisotropy of the electronic system exhibits a discontinuous change, leading to a meta-nematic tra...

  10. Galactic foreground contribution to the BEAST CMB Anisotropy Maps

    OpenAIRE

    Mejía, Jorge; Bersanelli, Marco; Burigana, Carlo; Childers, Jeff; Figueiredo, Newton; Kangas, Miikka; Lubin, Philip; Maino, Davide; Mandolesi, Nazzareno; Marvil, Josh; Meinhold, Peter; O'Dwyer, Ian; O'Neill, Hugh,; Platania, Paola; Seiffert, Michael

    2004-01-01

    We report limits on the Galactic foreground emission contribution to the Background Emission Anisotropy Scanning Telescope (BEAST) Ka- and Q-band CMB anisotropy maps. We estimate the contribution from the cross-correlations between these maps and the foreground emission templates of an H${\\alpha}$ map, a de-striped version of the Haslam et al. 408 MHz map, and a combined 100 $\\mu$m IRAS/DIRBE map. Our analysis samples the BEAST $\\sim10^\\circ$ declination band into 24 one-hour (RA) wide sector...

  11. Probing the Solar System

    Science.gov (United States)

    Wilkinson, John

    2013-01-01

    Humans have always had the vision to one day live on other planets. This vision existed even before the first person was put into orbit. Since the early space missions of putting humans into orbit around Earth, many advances have been made in space technology. We have now sent many space probes deep into the Solar system to explore the planets and…

  12. One-Probe Search

    DEFF Research Database (Denmark)

    Östlin, Anna; Pagh, Rasmus

    2002-01-01

    We consider dictionaries that perform lookups by probing a single word of memory, knowing only the size of the data structure. We describe a randomized dictionary where a lookup returns the correct answer with probability 1 - e, and otherwise returns don't know. The lookup procedure uses an expan...

  13. 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

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

    OpenAIRE

    Dalla, S.; Balogh, A.

    2000-01-01

    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 A...

  15. Anisotropy in the electronic states of self-assembled quantum dots

    International Nuclear Information System (INIS)

    Full text: Self-assembled quantum dots (QD) are semiconductor nanostructures that have been widely reported for use in technological devices such as optical memories and detectors. Besides this commercial potential, their zero-dimensional characteristics unveil a vast realm of fundamental physics to be explored in condensed matter physics. An example is the tailorable InAsP QD system, which allows one to control emission energy and QD sizes, among other properties. In this work we use polarized optical techniques in order to determine the origin of some structures previously identified via photoluminescence (PL) and photomodulated transmission (PT). We show that by varying the linear polarization of either excitation beam (PL) or probe beam (PT) it was possible to identify both QD and wetting layer (WL) contributions for the optical spectra of InAsP QDs. PT shows clearly that lower energy spectral structures present an anisotropy as a function of the polarization direction, which can be associated to QD recombination, since some degree of spatial anisotropy is expected for these nanostructures. WL contributions, however, appears at higher energies and shows isotropic behavior as a function of linear polarization, a characteristics of a two-dimensional layer. Polarized PL measurements seem to confirm the above identification, however a slightly dependence on WL intensity as a function of excitation polarization was found; it might be related to the diffraction grating polarization response of our spectrometer, and this is under investigation at the moment. Higher states for both WL and QD, although faint in the spectra, are present for samples with deeper confining potentials. (author)

  16. Experimental Study of Rock Drill-ability Anisotropy by Acoustic Velocity

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Rock drill-ability anisotropy has significant effects on directional drilling and deviation control. Its evaluation is an important but difficult research subject. Definitions of drill-ability anisotropy and acoustic anisotropy of rock are given in this paper. The acoustic velocities and the drill-ability parameters of several rock samples from the Engineering Center for Chinese Continental Scientific Drilling (CCSD) are respectively measured with the device for testing the rock drill-ability and the ultrasonic testing system in laboratory, so that their drill-ability anisotropy and acoustic anisotropy are respectively calculated and discussed in detail by using the experimental data. On the basis of these experimental results and calculations, correlations between drill-ability anisotropy and acoustic anisotropy of the rock samples are illustrated through regression analyses. Thus, a mathematical model developed may be used to evaluate the rock drill-ability anisotropy with the acoustic logging or seismic data to a certain extent.

  17. Anisotropy of sublimation from equivalent crystal faces of carbon-containing tungsten monocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Dekhtyar, I.Ya.; Kolesnik, V.N.; Ovsienko, D.E.; Patoka, V.I.; Silant' ev, V.I.; Sosnina, E.I. (AN Ukrainskoj SSR, Kiev. Inst. Metallofiziki)

    1981-08-01

    Anisotropy of sublimation parameters was found in equivalent faces (100) or (1O0) of W single crystals oriented perpendicular or parallel to the growth direction. The anisotropy value depends on C concentration in W single crystals.

  18. Anisotropy of sublimation from equivalent crystal faces of carbon-containing tungsten monocrystals

    International Nuclear Information System (INIS)

    Anisotropy of sublimation parameters was found in equivalent faces (100) or (1O0) of W single crystals oriented perpendicular or parallel to the growth direction. The anisotropy value depends on C concentration in W single crystals

  19. Anomalous Electronic Anisotropy Triggered by Ferroelastic Coupling in Multiferroic Heterostructures.

    Science.gov (United States)

    Ju, Changcheng; Yang, Jan-Chi; Luo, Cheng; Shafer, Padraic; Liu, Heng-Jui; Huang, Yen-Lin; Kuo, Ho-Hung; Xue, Fei; Luo, Chih-Wei; He, Qing; Yu, Pu; Arenholz, Elke; Chen, Long-Qing; Zhu, Jinsong; Lu, Xiaomei; Chu, Ying-Hao

    2016-02-01

    The ferroelastic strain coupling in multiferroic heterostructures is explored aiming at novel physical effects and fascinating functionality. Ferroelastic domain walls in manganites induced by a stripe BiFeO3 template can modulate the electronic transfer and sufficiently block the magnetic ordering, creating a vast anisotropy. The findings suggest the great importance of ferroelastic strain engineering in material modifications. PMID:26640119

  20. Grain boundary enegineering and alterations in anisotropy of interfacial properties

    Czech Academy of Sciences Publication Activity Database

    Lejček, Pavel; Gärtnerová, Viera; Jäger, Aleš

    654-656, - (2010), s. 2350-2353. ISSN 0255-5476 R&D Projects: GA AV ČR KAN300100801; GA ČR GA106/08/0369 Institutional research plan: CEZ:AV0Z10100520 Keywords : grain boundary segregation, * anisotropy * compensation effect * thermodynamics Subject RIV: BM - Solid Matter Physics ; Magnetism

  1. 3D analyses of cavitation instabilities accounting for plastic anisotropy

    DEFF Research Database (Denmark)

    Legarth, Brian Nyvang; Tvergaard, Viggo

    2010-01-01

    main focus is on the effect of different degrees of plastic anisotropy. Loading cases are considered, where all the macroscopic principal stresses differ. The numerical quasi‐static solutions are obtained by a full transient analysis of the equations of motion, in which the loading is applied so slowly...

  2. Window Function for Non-Circular Beam CMB Anisotropy Experiment

    OpenAIRE

    Souradeep, Tarun; Ratra, Bharat

    2001-01-01

    We develop computationally rapid methods to compute the window function for a cosmic microwave background anisotropy experiment with a non-circular beam which scans over large angles on the sky. To concretely illustrate these methods we compute the window function for the Python V experiment which scans over large angles on the sky with an elliptical Gaussian beam.

  3. Exotic skyrmion crystals in chiral magnets with compass anisotropy

    Science.gov (United States)

    Chen, J. P.; Zhang, Dan-Wei; Liu, J. -M.

    2016-01-01

    The compass-type anisotropy appears naturally in diverse physical contexts with strong spin-orbit coupling (SOC) such as transition metal oxides and cold atomic gases etc, and it has been receiving substantial attention. Motivated by recent studies and particularly recent experimental observations on helimagnet MnGe, we investigate the critical roles of this compass-type anisotropy in modulating various spin textures of chiral magnets with strong SOC, by Monte Carlo simulations based on a classical Heisenberg spin model with Dzyaloshinsky-Moriya interaction and compass anisotropy. A phase diagram with emergent spin orders in the space of compass anisotropy and out-of-plane magnetic field is presented. In this phase diagram, we propose that a hybrid super-crystal structure consisting of alternating half-skyrmion and half-anti-skyrmion is the possible zero-field ground state of MnGe. The simulated evolution of the spin structure driven by magnetic field is in good accordance with experimental observations on MnGe. Therefore, this Heisenberg spin model successfully captures the main physics responsible for the magnetic structures in MnGe, and the present work may also be instructive to research on the magnetic states in other systems with strong SOC. PMID:27377149

  4. The importance of anisotropy for relativistic fluids with spherical symmetry

    OpenAIRE

    Ivanov, B. V.

    2010-01-01

    It is shown that an effective anisotropic spherically symmetric fluid model with heat flow can absorb the addition to a perfect fluid of pressure anisotropy, heat flow, bulk and shear viscosity, electric field and null fluid. In most cases the induction of effective heat flow can be avoided.

  5. Flow stress anisotropy caused by geometrically necessary boundaries

    DEFF Research Database (Denmark)

    Hansen, N.; Juul Jensen, D.

    1992-01-01

    The microstructural anisotropy of deformed metal is related to the formation of geometrically necessary boundaries such as dense dislocation walls and microbands. These boundaries have a macroscopic orientation with respect to the sample axes and they can resist slip due to a high concentration of...

  6. K Variations and Anisotropy: Microstructure Effect and Numerical Predictions

    Institute of Scientific and Technical Information of China (English)

    李旭东; 李华清

    2003-01-01

    Computer experiments were performed on simulated polycrystalline material samples that possess locally anisotropic microstructures to investigate stress intensity factor ( K ) variations and anisotropy along fronts of microcracks of different sizes. The anisotropic K , arising from inhomogeneous stresses in broken grains, was determined for planar microcracks by using a weight function-based numerical technique. It has been found that the grain-orientation-geometry-induced local anisotropy produces large variations in K along front of microcracks, when the crack size is of the order of few grain diameters. Synergetic effect of grain orientation and geometry of broken grains control K variations and evolution along the microcrack front. The K variations may diminish at large crack sizes, signifying a shift of K calculation to bulk stress dependence from local stress dependence. Local grain geometry and texture may lead to K anisotropy, producing unusually higher/lower K at a segment of the crack front. Either K variation or anisotropy cannot be ignored when assessing a microcrack.

  7. Anisotropy of the magnetocaloric effect in DyNiAl

    Czech Academy of Sciences Publication Activity Database

    Kaštil, J.; Javorský, P.; Andreev, Alexander V.

    2009-01-01

    Roč. 321, č. 15 (2009), s. 2318-2321. ISSN 0304-8853 Institutional research plan: CEZ:AV0Z10100520 Keywords : magnetocaloric effec * DyNiAl * magnetism * anisotropy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.204, year: 2009

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

    International Nuclear Information System (INIS)

    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

  9. Large-Angular Scales CMB Anisotropy from Excited Initial Mode

    CERN Document Server

    Sojasi, A; Yusofi, E

    2015-01-01

    According to the inflationary cosmology, the CMB anisotropy gives an opportunity to test predictions of the new physics hypothesis. Initial state of quantum fluctuations is one of the important options at high energy scale, which can affect on the observables such as CMB power spectrum. In this study a quasi-de Sitter inflationary background with approximate de Sitter mode function built over the Bunch-Davies mode is applied to investigate the scale-dependency of the CMB anisotropy. Indeed, considering the recent Planck constraint on spectral index, motivated us to examine the effect of new excited mode function (instead of pure de Sitter mode) on the CMB anisotropy in large-angular scales. In so doing, it was revealed that the angular scale-invariance in the CMB temperature fluctuations is broken and in the limit $ \\ell<200 $ the tiny deviation is appeared. Also, it was shown that the power spectrum of CMB anisotropy is dependent on the slow-roll parameter $\\epsilon $.

  10. Influence of magnetic anisotropy on the superferromagnetic ordering in nanocomposites

    DEFF Research Database (Denmark)

    Mørup, Steen; Christiansen, Gunnar Dan

    1993-01-01

    Magnetic interaction between ultrafine particles may result in superferromagnetism, i.e., ordering of the magnetic moments of particles which would be superparamagnetic if they were noninteracting. In this article we discuss the influence of the magnetic anisotropy on the temperature dependence of...... the order parameter. Journal of Applied Physics is copyrighted by The American Institute of Physics....

  11. Large-Angular-Scale Anisotropy in the Cosmic Background Radiation

    Science.gov (United States)

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

    1980-05-01

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

  12. Diamagnetic Anisotropy: Two Iron Complexes as Laboratory Examples

    Science.gov (United States)

    Fernandez, Ignacio; Sanchez, Jorge Fernando Fernandez

    2010-01-01

    There are relatively few experiments describing the NMR properties of bis(amine) iron(II) phthalocyanine complexes. Several features make this experiment attractive: First, it nicely illustrates the diamagnetic anisotropy phenomena, providing both students and teachers an opportunity to gain insight into aspects such as phase correction and…

  13. Effect of earthquake locations on Rayleigh wave azimuthal anisotropy

    Science.gov (United States)

    Ma, Z.; Masters, G.

    2013-12-01

    We have compiled a large dataset for Rayleigh wave phase arrival times from 5mHz to 35mHz by using cluster analysis method. Estimation of source phase is improved by using a second order approximation of the associated Legendre functions. Currently, we have about 300,000 measurements for 5mHz, 600,000 for 10mHz, 400,000 for 20mHz and 280,000 for 35mHz. We use our new dataset to invert for the 2-phi terms of Rayleigh wave azimuthal anisotropy. We have found differences in the inverted fast directions when using PDE versus CMT source locations, especially near subduction zones where most earthquakes happen. Allowing small changes in earthquake locations (latitude and longitude) in our inversion greatly reduces such discrepancies. Residue patterns and checkerboard tests both indicate that the azimuthal anisotropy patterns in ocean basins are likely coherent over large distances, especially in the Pacific. To model the change of anisotropy amplitudes in the Pacific for different frequencies, we follow the approach proposed by Montagner and Nataf (1986). Values of elastic constants are compiled from Anderson and Isaak (1995) and Abramson et al (1997). The depth extent of anisotropy will be discussed.

  14. Anisotropie d'agrégats de cobalt

    OpenAIRE

    Morel, Robert

    2009-01-01

    Ce mémoire présente une revue sur la croissance d'agrégats de cobalt par condensation en phase gazeuse. Suit une revue des différent mécanismes physiques à l'origine de l'anisotropie magnétique du cobalt, et de leurs manifestations dans des particules nanométriques.

  15. Influence of thermal heating to elastic anisotropy of granulites

    Czech Academy of Sciences Publication Activity Database

    Lokajíček, Tomáš; Rudajev, Vladimír; Goel, R.; Dwivedi, R.; Swarup, A.

    s. l. : European Seismological Comission, 2010. -----. [European Seismological Comission General Assembly /32./. 06.09.2010-10.09.2010, Montpellier] R&D Projects: GA AV ČR IAA300130906 Institutional research plan: CEZ:AV0Z30130516 Keywords : elastic anisotropy * granulites * thermal heating Subject RIV: DC - Siesmology, Volcanology, Earth Structure

  16. Photoinduzierte Mikrostrukturierung und Anisotropie in Bakteriorhodopsin-Filmen

    OpenAIRE

    Yang, Zijiang

    2009-01-01

    Im Rahmen dieser Dissertation wurden zwei Effekte von Bakteriorhodopsin untersucht. Im ersten Teil der Arbeit wurde die photoinduzierte Mikrostrukturierung erforscht und ihre Anwendung zur Darstellung von Beugungsgittern gezeigt. Im zweiten Teil wurde die photoinduzierte Anisotropie untersucht und für die Datenspeicherung mit mehreren Informationen angewendet.

  17. Exotic skyrmion crystals in chiral magnets with compass anisotropy

    Science.gov (United States)

    Chen, J. P.; Zhang, Dan-Wei; Liu, J.-M.

    2016-07-01

    The compass-type anisotropy appears naturally in diverse physical contexts with strong spin-orbit coupling (SOC) such as transition metal oxides and cold atomic gases etc, and it has been receiving substantial attention. Motivated by recent studies and particularly recent experimental observations on helimagnet MnGe, we investigate the critical roles of this compass-type anisotropy in modulating various spin textures of chiral magnets with strong SOC, by Monte Carlo simulations based on a classical Heisenberg spin model with Dzyaloshinsky-Moriya interaction and compass anisotropy. A phase diagram with emergent spin orders in the space of compass anisotropy and out-of-plane magnetic field is presented. In this phase diagram, we propose that a hybrid super-crystal structure consisting of alternating half-skyrmion and half-anti-skyrmion is the possible zero-field ground state of MnGe. The simulated evolution of the spin structure driven by magnetic field is in good accordance with experimental observations on MnGe. Therefore, this Heisenberg spin model successfully captures the main physics responsible for the magnetic structures in MnGe, and the present work may also be instructive to research on the magnetic states in other systems with strong SOC.

  18. AMiBA-array for microwave background anisotropy

    Science.gov (United States)

    Kesteven, M.

    2002-03-01

    AMiBA is a 90 GHz interferometric array of the ASIAA (Academia Sinica, Institue of Astronomy and Astrophysics). It will make a detailed study of the polarization of the CMB anisotropy; it will also undertake a survey of Sunyaev-Zel'dovich clusters. It is under construction at present, with an expected completion date of late 2003. .

  19. Seismic anisotropy of serpentinite from Val Malenco, Italy

    Czech Academy of Sciences Publication Activity Database

    Kern, H.; Lokajíček, Tomáš; Svitek, Tomáš; Wenk, H.-R.

    2015-01-01

    Roč. 120, č. 6 (2015), s. 4113-4129. ISSN 2169-9313 R&D Projects: GA MŠk LH13102 Institutional support: RVO:67985831 Keywords : serpentinite * anisotropy Subject RIV: DE - Earth Magnetism, Geodesy, Geography Impact factor: 3.440, year: 2013

  20. On the magnetocrystalline anisotropy of greigite (Fe3S4)

    Science.gov (United States)

    Winklhofer, Michael; Chang, Liao; Eder, Stephan H. K.

    2014-04-01

    ferrimagnetic mineral greigite (cubic Fe3S4) is well known as an intracellular biomineralization product in magnetic bacteria and as a widely occurring authigenic mineral in anoxic sediments. Due to the lack of suitable single-crystal specimens, the magnetic anisotropy parameters of greigite have remained poorly constrained, to the point where not even the easy axis of magnetization is known. Here we report on an effort to determine the anisotropy parameters on the basis of ferromagnetic resonance (FMR) powder spectroscopy on hydrothermally synthesized, chemically pure greigite microcrystals dispersed in a nonmagnetic matrix. In terms of easy axis orientations, the FMR data are consistent with or , or less likely, a more general type. With a g factor of 2.09, the anisotropy field is about 90 mT and in some samples may reach 125 mT, compared to 30 mT for cubic magnetite. This confirms the dominating role of cubic anisotropy on the magnetic properties of greigite, which we show to be responsible for large SIRM/k values. K1 is in the range -15 … -23 J/m3 () or +10 … +15 kJ/m3 (), yielding upper limits of 44 or 34 nm for the superparamagnetic grain size, respectively.

  1. On the magnetocrystalline anisotropy of greigite (Fe3S 4)

    NARCIS (Netherlands)

    Winklhofer, M.; Chang, L.; Eder, S.H.K.

    2014-01-01

    The ferrimagnetic mineral greigite (cubic Fe3S4) is well known as an intracellular biomineralization product in magnetic bacteria and as a widely occurring authigenic mineral in anoxic sediments. Due to the lack of suitable single-crystal specimens, the magnetic anisotropy parameters of greigite hav

  2. Photoinduced Circular Anisotropy in Side-Chain Azobenzene Polyesters

    DEFF Research Database (Denmark)

    Nikolova, L.; Todorov, T.; Ivanov, M.;

    1997-01-01

    We report for the first time the inducing of large circular anisotropy in previously unoriented films of side-chain azobenzene polyesters on illumination with circularly polarized light at a wavelength of 488 nm. The circular dichroism and optical activity are measured simultaneously in real time...

  3. Controlling the structural and functional anisotropy of engineered cardiac tissues

    International Nuclear Information System (INIS)

    The ability to control the degree of structural and functional anisotropy in 3D engineered cardiac tissues would have high utility for both in vitro studies of cardiac muscle physiology and pathology as well as potential tissue engineering therapies for myocardial infarction. Here, we applied a high aspect ratio soft lithography technique to generate network-like tissue patches seeded with neonatal rat cardiomyocytes. Fabricating longer elliptical pores within the patch networks increased the overall cardiomyocyte and extracellular matrix alignment within the patch. Improved uniformity of cell and matrix alignment yielded an increase in anisotropy of action potential propagation and faster longitudinal conduction velocity (LCV). Cardiac tissue patches with a higher degree of cardiomyocyte alignment and electrical anisotropy also demonstrated greater isometric twitch forces. After two weeks of culture, specific measures of electrical and contractile function (LCV = 26.8 ± 0.8 cm s−1, specific twitch force = 8.9 ± 1.1 mN mm−2 for the longest pores studied) were comparable to those of neonatal rat myocardium. We have thus described methodology for engineering of highly functional 3D engineered cardiac tissues with controllable degree of anisotropy. (paper)

  4. 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.

  5. Uniaxial strain controlling magnetic anisotropy in (Ga,Mn)As

    Czech Academy of Sciences Publication Activity Database

    Zemen, Jan; Jungwirth, Tomáš; Wunderlich, J.; Gallagher, B. L.

    2007-01-01

    Roč. 112, č. 2 (2007), 431-435. ISSN 0587-4246 Grant ostatní: NANOSPIN(XE) FP6-2002-IST-015728 Institutional research plan: CEZ:AV0Z10100521 Keywords : ferromagnetic semiconductors * magnetocrystalline anisotropy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.340, year: 2007

  6. Galactic foreground contribution to the BEAST CMB Anisotropy Maps

    CERN Document Server

    Mejia, J; Burigana, C; Childers, J; Figueiredo, N; Kangas, M; Lubin, P; Maino, D; Mandolesi, N; Marvil, J; Meinhold, P; O'Dwyer, I; O'Neill, H; Platania, P; Seiffert, M; Stebor, N; Tello, C A S; Villela, T; Wandelt, B; Wünsche, C A; Mej\\'{\\i}a, Jorge; Bersanelli, Marco; Burigana, Carlo; Childers, Jeff; Figueiredo, Newton; Kangas, Miikka; Lubin, Philip; Maino, Davide; Mandolesi, Nazzareno; Marvil, Josh; Meinhold, Peter; Dwyer, Ian O'; Neill, Hugh O'; Platania, Paola; Seiffert, Michael; Stebor, Nathan; Tello, Camilo; Villela, Thyrso; Wandelt, Benjamin; Wuensche, Carlos Alexandre

    2004-01-01

    We report limits on the Galactic foreground emission contribution to the Background Emission Anisotropy Scanning Telescope (BEAST) Ka- and Q-band CMB anisotropy maps. We estimate the contribution from the cross-correlations between these maps and the foreground emission templates of an H${\\alpha}$ map, a de-striped version of the Haslam et al. 408 MHz map, and a combined 100 $\\mu$m IRAS/DIRBE map. Our analysis samples the BEAST $\\sim10^\\circ$ declination band into 24 one-hour (RA) wide sectors with $\\sim7900$ pixels each, where we calculate: (a) the linear correlation coefficient between the anisotropy maps and the templates; (b) the coupling constants between the specific intensity units of the templates and the antenna temperature at the BEAST frequencies and (c) the individual foreground contributions to the BEAST anisotropy maps. The peak sector contributions of the contaminants in the Ka-band are of 56.5% free-free with a coupling constant of $8.3\\pm0.4$ $\\mu$K/R, and 67.4% dust with $45.0\\pm2.0$ $\\mu$K/...

  7. Mobile Probes in Mobile Learning

    OpenAIRE

    Ørngreen, Rikke; Blomhøj, Ulla; Duvaa, Uffe

    2011-01-01

    In this paper experiences from using mobile probes in educational design of a mobile learning application is presented. The probing process stems from the cultural probe method, and was influenced by qualitative interview and inquiry approaches. In the project, the mobile phone was not only acting as an agent for acquiring empirical data (as the situation in hitherto mobile probe settings) but was also the technological medium for which data should say something about (mobile learning). Conse...

  8. Probing Properties of Cold Radiofrequency Plasma with Polymer Probe

    CERN Document Server

    Bormashenko, Edward; Multanen, Victor

    2014-01-01

    The probe intended for the characterization of cold plasma is introduced. The probe allows estimation of the Debye length of the cold plasma. The probe is based on the pronounced modification of surface properties (wettability) of polymer films by cold plasmas. The probe was tested with the cold radiofrequency inductive air plasma discharge. The Debye length and the concentration of charge carriers were estimated for various gas pressures. The reported results coincide reasonably with the corresponding values established by other methods. The probe makes possible measurement of characteristics of cold plasmas in closed chambers.

  9. ATA probe beam experiment

    International Nuclear Information System (INIS)

    The philosophy of these tests is to measure the motion of a low current, small diameter electron beam in the accelerator before running high current. By using low current, we can study particle motion in the applied fields without any extra complications associated with the self-forces of high currents. With the steering magnets off, we have measured the transverse drift of the probe beam. Also, we have used the probe beam to optimize the current in the steering magnets to compensate for the drift. There have been concurrent efforts to locate the source of the error field which is presumed to cause the drift. So far, the source has not been established but the search is continuing

  10. Magnetism of One-Dimensional Dipolar-Interaction Spin Chains with Perpendicular Anisotropy*

    Institute of Scientific and Technical Information of China (English)

    ZHANG Kai-Cheng; ZHU Yan

    2011-01-01

    We have investigated the magnetism of one-dimensional dipolar-interaction spin chains with perpendicular anisotropy by simulation.The behaviors of the magnetizations and the orientation correlations change dramatically as the anisotropy increases to the critical value.The domain length can be controlled by adjusting the temperature and the external field as well as the anisotropy.These properties are interesting and arise from the competition between the anisotropy and the interaction along the chain.

  11. Anisotropy of thermal expansion and electric resistance of cermet germanium telluride

    International Nuclear Information System (INIS)

    Anisotropies of thermal expansion α and electric resistance ρ of cermet germanium telluride were investigated depending on pressing conditions. It is shown that anisotropy of cermet germanium telluride depends sufficiently on pressing conditions with respect to thermal expansion and electric resistance. It was established that anisotropy of the cermet germanium telluride was strongly affected by pressing force and temperature. Anisotropy of the cermet germanium telluride also depends with respect to α and ρ on the material and size of the mould

  12. Properties of Broezel static probe

    Science.gov (United States)

    Gašparovič, Peter; Semrád, Karol; Cúttová, Miroslava

    2016-03-01

    The properties of flat static probe designed by Broezel and used in sailplanes are investigated for its planned use in low speed tunnel. Both the numerical CFD model and experiment in low speed wind tunnel confirm yaw insensitivity of the static pressure measured by the probe. The results indicate that the probe is sufficiently accurate for its planned use in wind tunnel measurements.

  13. Scanning Probe Microscopy and Spectroscopy

    Science.gov (United States)

    Wiesendanger, Roland

    1994-09-01

    Preface; List of acronyms; Introduction; Part I. Experimental Methods and Theoretical Background of Scanning Probe Microscopy and Spectroscopy: 1. Scanning tunnelling microscopy; 2. Scanning force microscopy; 3. Related scanning probe techniques; Part II. Applications of Scanning Probe Microscopy and Spectroscopy: 4. Condensed matter physics; 5. Chemistry; 6. Organic materials; 7. Metrology and standards; 8. Nanotechnology; References; Index.

  14. Ultrasonic temperature measuring probe

    International Nuclear Information System (INIS)

    The temperature measuring probe made of sensor wire and the tube encasing it is suited for being used in fuel columns at temperatures above 20000C. The thermal expansion coefficient, the linear dimensions, and the fastening points are chosen in such manner that the temperature fluctuations occuring during operation produce such relative variations in length that formation of bridges between sensor wire and encasing tube are suppressed already in the initial stage. (DG) 891 HP/DG 892 MKO

  15. Small-angle CMB temperature anisotropies induced by cosmic strings

    International Nuclear Information System (INIS)

    We use Nambu-Goto numerical simulations to compute the cosmic microwave background (CMB) temperature anisotropies induced at arcminute angular scales by a network of cosmic strings in a Friedmann-Lemaitre-Robertson-Walker (FLRW) expanding universe. We generate 84 statistically independent maps on a 7.2 deg. field of view, which we use to derive basic statistical estimators such as the one-point distribution and two-point correlation functions. At high multipoles, the mean angular power spectrum of string-induced CMB temperature anisotropies can be described by a power law slowly decaying as l-p, with p=0.889 (+0.001,-0.090) (including only systematic errors). Such a behavior suggests that a nonvanishing string contribution to the overall CMB anisotropies may become the dominant source of fluctuations at small angular scales. We therefore discuss how well the temperature gradient magnitude operator can trace strings in the context of a typical arcminute diffraction-limited experiment. Including both the thermal and nonlinear kinetic Sunyaev-Zel'dovich effects, the Ostriker-Vishniac effect, and the currently favored adiabatic primary anisotropies, we find that, on such a map, strings should be 'eye visible', with at least of order ten distinctive string features observable on a 7.2 deg. gradient map, for tensions U down to GU≅2x10-7 (in Planck units). This suggests that, with upcoming experiments such as the Atacama Cosmology Telescope (ACT), optimal non-Gaussian, string-devoted statistical estimators applied to small-angle CMB temperature or gradient maps may put stringent constraints on a possible cosmic string contribution to the CMB anisotropies.

  16. Einstein Inflationary Probe (EIP)

    Science.gov (United States)

    Hinshaw, Gary

    2004-01-01

    I will discuss plans to develop a concept for the Einstein Inflation Probe: a mission to detect gravity waves from inflation via the unique signature they impart to the cosmic microwave background (CMB) polarization. A sensitive CMB polarization satellite may be the only way to probe physics at the grand-unified theory (GUT) scale, exceeding by 12 orders of magnitude the energies studied at the Large Hadron Collider. A detection of gravity waves would represent a remarkable confirmation of the inflationary paradigm and set the energy scale at which inflation occurred when the universe was a fraction of a second old. Even a strong upper limit to the gravity wave amplitude would be significant, ruling out many common models of inflation, and pointing to inflation occurring at much lower energy, if at all. Measuring gravity waves via the CMB polarization will be challenging. We will undertake a comprehensive study to identify the critical scientific requirements for the mission and their derived instrumental performance requirements. At the core of the study will be an assessment of what is scientifically and experimentally optimal within the scope and purpose of the Einstein Inflation Probe.

  17. Weak-anisotropy moveout approximations for P-waves in homogeneous layers of monoclinic or higher anisotropy symmetries

    Czech Academy of Sciences Publication Activity Database

    Farra, V.; Pšenčík, Ivan; Jílek, P.

    2016-01-01

    Roč. 81, č. 2 (2016), C39-C59. ISSN 0016-8033 R&D Projects: GA ČR(CZ) GAP210/11/0117 Keywords : anisotropy * P-wave * traveltime * moveout Subject RIV: DC - Siesmology, Volcanology, Earth Structure

  18. ContainerProbe-Net

    International Nuclear Information System (INIS)

    ContainerProbe-Net is a global system concept for high throughput Risk Screening of inter-modal containers while they are in motion. It will have the following detection capabilities: 1. Mis-declared hazardous materials: - illegal waste exports or imports; - hazardous materials causing many annual maritime insurance claims; - accumulated pest poisons. 2. Contraband materials: - smuggled and counterfeit goods to avoid import duties and restrictions; - narcotic drugs; - weapons for criminals; - illegal immigrants. 3. Terrorism materials: - explosives and precursors - Weapons of Mass Destruction - fissile materials. The demand for this type of detection capability with high throughput has been declared by the EU, USA and other nations as a consequence of the rising policy of Civil Security. Efforts to advocate ContainerProbe-Net to both U.S.A. and EU security research administrators are progressing as the private investment base grows. ContainerProbe-Net directly addresses the 100% Risk Screening of containers requirement. Neutron interrogation of each container on a train or on an automated vehicle passing through the ContainerProbe portal will provide information about the bulk elemental composition of the contents. A burst of pulsed neutrons for a combination of prompt γ and secondary neutron emissions can provide a measured 'fingerprint' which will remain constant from the start to the end of the container's journey. A period of two seconds is available per container in order to capture data for each container on a moving train. Contents of containers are already, to some extent, registered in the export logistics databases. However these disparate systems have evolved with computer science and the needs of ports and customs authorities. Today such systems are far from complete. The global access to such registered container data and the fusion of this information with actual physical measurement data is the Network part of the concept. Risk screening implies

  19. Comparative evaluation of probing depth and clinical attachment level using a manual probe and Florida probe

    Directory of Open Access Journals (Sweden)

    Amandeep Kour

    2016-01-01

    Full Text Available Background: To compare and evaluate the intra- and inter-examiner efficacy and reproducibility of the first-generation manual (Williams probe and the third-generation Florida probe in terms of measuring pocket probing depth (PD and clinical attachment level (CAL. Materials and Methods: Forty subjects/4000 sites were included in this comparative, cross-sectional study. Group- and site-wise categorizations were done. Based on gingival index, PD, and CAL, patients were divided into four groups, i.e., periodontally healthy, gingivitis, mild to moderate periodontitis, and severe periodontitis. Further, based on these parameters, a total of 4000 sites, with 1000 sites in each category randomly selected from these 40 patients, were taken. Full mouth PD and CAL measurements were recorded with two probes, by Examiner 1 and on Ramfjord teeth by Examiner 2. Results: Full mouth and Ramfjord teeth group- and site-wise PD obtained with the manual probe by both the examiners were statistically significantly deeper than that obtained with the Florida probe. The full mouth and Ramfjord teeth mean CAL measurement by Florida probe was higher as compared to manual probe in mild to moderate periodontitis group and sites, whereas in severe periodontitis group and sites, manual probe recorded higher CAL as compared to Florida probe. Conclusion: Mean PD and CAL measurements were deeper with the manual probe as compared to the Florida probe in all the groups and sites, except for the mild-moderate periodontitis group and sites where the CAL measurements with the manual probe were less than the Florida probe. Manual probe was more reproducible and showed less interexaminer variability as compared to the Florida probe.

  20. 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

  1. Probe-based data storage

    CERN Document Server

    Koelmans, Wabe W; Abelmann, L

    2015-01-01

    Probe-based data storage attracted many researchers from academia and industry, resulting in unprecendeted high data-density demonstrations. This topical review gives a comprehensive overview of the main contributions that led to the major accomplishments in probe-based data storage. The most investigated technologies are reviewed: topographic, phase-change, magnetic, ferroelectric and atomic and molecular storage. Also, the positioning of probes and recording media, the cantilever arrays and parallel readout of the arrays of cantilevers are discussed. This overview serves two purposes. First, it provides an overview for new researchers entering the field of probe storage, as probe storage seems to be the only way to achieve data storage at atomic densities. Secondly, there is an enormous wealth of invaluable findings that can also be applied to many other fields of nanoscale research such as probe-based nanolithography, 3D nanopatterning, solid-state memory technologies and ultrafast probe microscopy.

  2. Modeling of current characteristics of segmented Langmuir probe on DEMETER

    Energy Technology Data Exchange (ETDEWEB)

    Imtiaz, Nadia; Marchand, Richard [Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E1 (Canada); Lebreton, Jean-Pierre [Laboratoire de Physique et Chimie de l' Environnement et de l' Espace (LPC2E), CNRS-Université d' Orléans, Orléans Cedex (France)

    2013-05-15

    We model the current characteristics of the DEMETER Segmented Langmuir probe (SLP). The probe is used to measure electron density and temperature in the ionosphere at an altitude of approximately 700 km. It is also used to measure the plasma flow velocity in the satellite frame of reference. The probe is partitioned into seven collectors: six electrically insulated spherical segments and a guard electrode (the rest of the sphere and the small post). Comparisons are made between the predictions of the model and DEMETER measurements for actual ionospheric plasma conditions encountered along the satellite orbit. Segment characteristics are computed numerically with PTetra, a three-dimensional particle in cell simulation code. In PTetra, space is discretized with an unstructured tetrahedral mesh, thus, enabling a good representation of the probe geometry. The model also accounts for several physical effects of importance in the interaction of spacecraft with the space environment. These include satellite charging, photoelectron, and secondary electron emissions. The model is electrostatic, but it accounts for the presence of a uniform background magnetic field. PTetra simulation results show different characteristics for the different probe segments. The current collected by each segment depends on its orientation with respect to the ram direction, the plasma composition, the magnitude, and the orientation of the magnetic field. It is observed that the presence of light H{sup +} ions leads to a significant increase in the ion current branch of the I-V curves of the negatively polarized SLP. The effect of the magnetic field is demonstrated by varying its magnitude and direction with respect to the reference magnetic field. It is found that the magnetic field appreciably affects the electron current branch of the I-V curves of certain segments on the SLP, whereas the ion current branch remains almost unaffected. PTetra simulations are validated by comparing the computed

  3. Radiative transfer studies and Next-Generation NIR probe prototype

    International Nuclear Information System (INIS)

    As a part of the PAT-KIVA project, this report summarizes the results of the work packages (WP's) 1.1 and 1.4. The WP1.4 consisted of laboratory studies to measure the absorption and scattering properties of several pharmaceutical powders. It also included the designing and building of the spectrometer accessories to make the measurements possible. The WP1.4 was needed to support of the WP1.1, where a wireless online probe of powder blend homogeneity was to be built. The idea was to be able to separate the chemical concentrations from the physical determinants of the powder blends by spatially resolved diffuse reflectance spectroscopy (SDR). The chemical concentrations were assumed, according to previous studies by others, to be faithfully represented in the calculated absorption coefficient. On the other hand, the physical properties like particle size distribution were assumed to be separated into the scattering coefficient and anisotropy factor. However, the studies indicated, that with the growth of particle size, these assumptions do not hold to any reasonable degree. Therefore it was decided not to design the online probe, but a laboratory research probe employing the SDR principle and being as versatile as possible regarding the wavelength range and illumination features. The design of the laboratory probe was nearly completed, but due to various reasons, it could not be built within the PAT-KIVA project. The main results of the WP1.4 were the building of spectrometer accessories and the measured optical properties of various powders. The main results of the WP1.1 were the preliminary comparison of SDR measurements to the 'reference' measurements done in WP1.4, and the near completion of the very challenging design task of the laboratory SDR probe. Another main result connected with both work packages was the development of simulation software to solve the inverse problem of calculating samples' optical properties from spectroscopic measurements. (orig.)

  4. Cleavable DNA-protein hybrid molecular beacon: A novel efficient signal translator for sensitive fluorescence anisotropy bioassay.

    Science.gov (United States)

    Hu, Pan; Yang, Bin

    2016-01-15

    Due to its unique features such as high sensitivity, homogeneous format, and independence on fluorescent intensity, fluorescence anisotropy (FA) assay has become a hotspot of study in oligonucleotide-based bioassays. However, until now most FA probes require carefully customized structure designs, and thus are neither generalizable for different sensing systems nor effective to obtain sufficient signal response. To address this issue, a cleavable DNA-protein hybrid molecular beacon was successfully engineered for signal amplified FA bioassay, via combining the unique stable structure of molecular beacon and the large molecular mass of streptavidin. Compared with single DNA strand probe or conventional molecular beacon, the DNA-protein hybrid molecular beacon exhibited a much higher FA value, which was potential to obtain high signal-background ratio in sensing process. As proof-of-principle, this novel DNA-protein hybrid molecular beacon was further applied for FA bioassay using DNAzyme-Pb(2+) as a model sensing system. This FA assay approach could selectively detect as low as 0.5nM Pb(2+) in buffer solution, and also be successful for real samples analysis with good recovery values. Compatible with most of oligonucleotide probes' designs and enzyme-based signal amplification strategies, the molecular beacon can serve as a novel signal translator to expand the application prospect of FA technology in various bioassays. PMID:26592607

  5. Plasma Membrane Lesions In Anthracycline-Resistant Tumor Cells Probed Using A Fluorescent Dye

    Science.gov (United States)

    Burke, Thomas G.; Doroshow, James H.

    1989-06-01

    Human cancer cells selected for resistance to several structurally unrelated cytotoxic drugs are known to display plasma membrane alterations such as amplified levels of a variety of glycoproteins, modifications in lipid composition, alterations in membrane fluidity and increased cellular fragility to osmotic shock. We have studied the plasma membrane fluidity of HL60 human leukemia cells and MCF-7 human breast cancer cells that have been selected for acquired resistance against the cytocidal effects of the anthracycline anticancer drug Adriamycin. Fluidity measurements were accomplished by evaluating the fluorescence anisotropy of the plasma membrane specific probe trimethylamino-1,6-dipihenylhexatriene (TMA.DPH) bound to whole, living cells. TMA.DPH anisotropy values for MCF-7 sensitive and 12-fold resistant cells were 0.306 and 0.285, respectively, while anisotropy values for HL-60 sensitive and 80-fold resistant cells lines were 0.310 and 0.295, respectively. In all cases, cell viability exceeded 97% and anisotropy values were subject to a day-to-day uncertainty of +/-2%. Our results demonstrate that increased plasma membrane fluidity apparently accompanies the development of resistance in both cell lines. Because it is known that increased membrane fluidity results in significantly decreased Adriamycin binding in artificial membrane systems, we propose here that decreased drug associations with fluidized, plasma membrane lipid bilayer regions may be a mechanism which contributes, in part, to the reduced rates of drug accumulation observed in HL60 and MCF-7 cells resistant to Adriamycin.

  6. Pump probe spectroscopy of quasiparticle dynamics in cuprate superconductors

    International Nuclear Information System (INIS)

    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

  7. Stress, strain rate and anisotropy in Kyushu, Japan

    Science.gov (United States)

    Savage, M. K.; Aoki, Y.; Unglert, K.; Ohkura, T.; Umakoshi, K.; Shimizu, H.; Iguchi, M.; Tameguri, T.; Ohminato, T.; Mori, J.

    2016-04-01

    Seismic anisotropy, the directional dependence of wave speeds, may be caused by stress-oriented cracks or by strain-oriented minerals, yet few studies have quantitatively compared anisotropy to stress and strain over large regions. Here we compare crustal stress and strain rates on the Island of Kyushu, Japan, as measured from inversions of focal mechanisms, GPS and shear wave splitting. Over 85,000 shear wave splitting measurements from local and regional earthquakes are obtained from the NIED network between 2004 and 2012, and on Aso, Sakurajima, Kirishima and Unzen volcano networks. Strain rate measurements are made from the Japanese Geonet stations. JMA-determined S arrival times processed with the MFAST shear wave splitting code measure fast polarisations (Φ), related to the orientation of the anisotropic medium and time delays (dt), related to the path length and the percent anisotropy. We apply the TESSA 2-D delay time tomography and spatial averaging code to the highest quality events, which have nearly vertical incidence angles, separating the 3455 shallow (depth = 40 km) earthquakes. Using square grids with 30 km sides for all the inversions, the best correlations are observed between splitting from shallow earthquakes and stress. Axes of maximum horizontal stress (SHmax) and Φ correlate with a coefficient c of 0.56, significant at the 99% confidence level. Their mean difference is 31.9°. Axes of maximum compressional strain rate and SHmax are also well aligned, with an average difference of 28°, but they do not correlate with each other, meaning that where they differ, the difference is not systematic. Anisotropy strength is negatively correlated with the stress ratio parameter determined from focal mechanism inversion (c = - 0.64; significant at the 99% confidence level). The anisotropy and stress results are consistent with stress-aligned microcracks in the crust in a dominantly strike-slip regime. Eigenvalues of maximum horizontal strain rate

  8. Diffusion creep in the mantle may create and maintain anisotropy

    Science.gov (United States)

    Wheeler, John

    2014-05-01

    Diffusion creep is thought to play an important role in lower mantle deformation and hence must be understood in detail if Earth behaviour is to be explained. It is commonly claimed that diffusion creep gives rise to equant grain shapes and destroys any crystallographic preferred orientation (CPO), so all physical properties would be isotropic. Some experiments on olivine support the first assertion but other minerals, and polyphase rocks, commonly show inequant grain shapes in nature and experiment even when diffusion creep is thought to be a major contribution to strain. Numerical models allow rigorous exploration of the effects of deformation under conditions not easily reached in experiments. A numerical model named 'DiffForm' (Wheeler & Ford 2007) gives insight into how grain shapes and microstructures evolve during diffusion creep. Modelling shows that whilst grains may initially rotate in apparently chaotic fashion during diffusion creep, such rotations slow down as grains become inequant. Consequently, an initial CPO (formed, for example, by dislocation creep at higher strain rates) will be decreased in intensity but not destroyed. Seismic anisotropy will decrease but not disappear (Wheeler 2009). Diffusion creep is also predicted to have intense mechanical anisotropy. In simple models diffusion creep is controlled entirely by diffusion and sliding along grain boundaries; there is no crystallographic influence. An aggregate of equant grains must then be mechanically isotropic, but a model microstructure with inequant grains has marked mechanical anisotropy (Wheeler 2010) - an effect related to the fact that grain boundary sliding is an intrinsic part of diffusion creep. That work was based on a very simple microstructure with a single inequant grain shape but I present here new results showing that for more complicated microstructures, mechanical anisotropy is intense even for quite modest grain elongations. There will be feedback between strain and

  9. Constraining depth-dependent anisotropy: A new approach

    Science.gov (United States)

    Ishii, M.; Okeler, A.

    2014-12-01

    Splitting of shear waves is commonly used to infer anisotropy of the Earth's interior. However, most data, such as SKS splitting, provide depth-integrated measure of anisotropy along the ray path, and it is difficult to separate contributions from different layers within the Earth. There have been efforts to focus on specific depth range by analyzing differences in splitting between two ray paths, but these studies only report observed differences or rely upon forward modeling with limited parameter-space search. We have developed a new approach to examine the P-to-S converted phases that allows one to construct depth-dependent multi-layer anisotropy models through combination of inversion and grid search. In addition to the conventional fast splitting direction and delay time, the technique allows one to investigate the tilt of the symmetry axis and dip of the discontinuity associated with the P-to-S conversion. Furthermore, the formulation is such that it naturally extends to include and examine multiple layers with different anisotropic properties. With these flexibilities, we can address anisotropic contributions from different layers in two separate procedures. The first scheme takes advantage of data with similar ray paths (e.g., SKS and SKKS waves recorded at the same station). The rays sample different structure when their ray paths differ (e.g., near the core-mantle boundary), but they sample the same structure when the paths are similar (e.g., in the upper part of the mantle and crust). Using our new approach, we can set up the problem as a two-layer anisotropy model where the layer with ray paths sampling different regions (e.g., lowermost mantle) is allowed to vary laterally. The second type of problem that can be addressed by the new approach is layer-by-layer investigation of anisotropy from top to bottom. This procedure combines the new method with receiver function analysis to obtain anisotropic properties of each layer using P-to-S converted waves

  10. Downscaling Smooth Tomographic Models: Separating Intrinsic and Apparent Anisotropy

    Science.gov (United States)

    Bodin, Thomas; Capdeville, Yann; Romanowicz, Barbara

    2016-04-01

    In recent years, a number of tomographic models based on full waveform inversion have been published. Due to computational constraints, the fitted waveforms are low pass filtered, which results in an inability to map features smaller than half the shortest wavelength. However, these tomographic images are not a simple spatial average of the true model, but rather an effective, apparent, or equivalent model that provides a similar 'long-wave' data fit. For example, it can be shown that a series of horizontal isotropic layers will be seen by a 'long wave' as a smooth anisotropic medium. In this way, the observed anisotropy in tomographic models is a combination of intrinsic anisotropy produced by lattice-preferred orientation (LPO) of minerals, and apparent anisotropy resulting from the incapacity of mapping discontinuities. Interpretations of observed anisotropy (e.g. in terms of mantle flow) requires therefore the separation of its intrinsic and apparent components. The "up-scaling" relations that link elastic properties of a rapidly varying medium to elastic properties of the effective medium as seen by long waves are strongly non-linear and their inverse highly non-unique. That is, a smooth homogenized effective model is equivalent to a large number of models with discontinuities. In the 1D case, Capdeville et al (GJI, 2013) recently showed that a tomographic model which results from the inversion of low pass filtered waveforms is an homogenized model, i.e. the same as the model computed by upscaling the true model. Here we propose a stochastic method to sample the ensemble of layered models equivalent to a given tomographic profile. We use a transdimensional formulation where the number of layers is variable. Furthermore, each layer may be either isotropic (1 parameter) or intrinsically anisotropic (2 parameters). The parsimonious character of the Bayesian inversion gives preference to models with the least number of parameters (i.e. least number of layers, and

  11. Anisotropy magnetic susceptibility measurements of vulcanic rock from merapi mountain in central Java

    International Nuclear Information System (INIS)

    Anisotropy Magnetic susceptibility indicated a differences of Magnetic susceptibility value of a sample due to the direction or orientation of magnetic field on it. The 22 sample's were taken from lour area around Merapi mountain in central Java and their Anisotropy Magnetic susceptibility were measured by using MS2 Bartington. The 22 sample's shown a high susceptibility value about 8037.5 x 105. Eleven sample's have high anisotropy ( it's anisotropy degree about 16% ). The rest of the sample have an anisotropy degree less than 6% (sample's from pasar bubar, Kali Kuning, Kali Gendong, Kali Gendol Utara). This result give an indication that a part of the sample's can be used for paleomagnetic

  12. Structural origins of magnetic anisotropy in sputtered amorphous Tb-Fe films

    International Nuclear Information System (INIS)

    Using x-ray-absorption fine-structure measurements we have obtained clear evidence for structural anisotropy in amorphous sputter-deposited TbFe films exhibiting perpendicular magnetic anisotropy. Modeling of the data shows that perpendicular anisotropy in these films is associated with Fe-Fe and Tb-Tb pair correlations which are greater in plane and Tb-Fe correlations which are greater perpendicular to the film plane. Upon annealing at 300 degree C the measured structural anisotropy disappears and the magnetic anisotropy decreases to a level consistent with magnetoelastic interactions between the film and substrate

  13. Spectroscopic ellipsometry investigations of optical anisotropy in obliquely deposited hafnia thin films

    Science.gov (United States)

    Tokas, R. B.; Jena, Shuvendu; Haque, S. Maidul; Rao, K. Divakar; Thakur, S.; Sahoo, N. K.

    2016-05-01

    In present work, HfO2 thin films have been deposited at various oblique incidences on Si substrates by electron beam evaporation. These refractory oxide films exhibited anisotropy in refractive index predictably due to special columnar microstructure. Spectroscopic ellipsometry being a powerful tool for optical characterization has been employed to investigate optical anisotropy. It was observed that the film deposited at glancing angle (80°) exhibits the highest optical anisotropy. Further, anisotropy was noticed to decrease with lower values of deposition angles while effective refractive index depicts opposite trend. Variation in refractive index and anisotropy has been explained in light of atomic shadowing during growth of thin films at oblique angles.

  14. Bubble and skyrmion crystals in frustrated magnets with easy-axis anisotropy

    Science.gov (United States)

    Hayami, Satoru; Lin, Shi-Zeng; Batista, Cristian D.

    2016-05-01

    We clarify the conditions for the emergence of multiple-Q structures out of lattice and easy-axis spin anisotropy in frustrated magnets. By considering magnets whose exchange interaction has multiple global minima in momentum space, we find that both types of anisotropy stabilize triple-Q orderings. Moderate anisotropy leads to a magnetic-field-induced skyrmion crystal, which evolves into a bubble crystal for increasing spatial and spin anisotropy. The bubble crystal exhibits a quasicontinuous (devil's staircase) temperature-dependent ordering wave vector, characteristic of the competition between frustrated exchange and strong easy-axis anisotropy.

  15. Pump-probe SAXS experiments on ultrafast demagnetization of magnetic multilayers

    International Nuclear Information System (INIS)

    We have investigated the ultrafast optical demagnetization of domain patterns in magnetic multilayers with perpendicular magnetic anisotropy in an infrared-pump x-ray-probe experiment. As a probe we used small angle x-ray scattering which, via x-ray magnetic circular dichroism at the Co M-edge, allows us to simultaneously obtain information on the magnitude of the local magnetization and the characteristic length scale of the magnetic domains. The free-electron laser source FLASH at Hamburg was tuned to deliver λ=20.9nm x-ray pulses of approx. 25 fs duration which were synchronized to an infrared fs laser for pump-probe experiments with sub-ps time resolution. In addition to ultrafast demagnetization, we observe sub-ps structural changes of the magnetic domain configuration. Models to explain this ultrafast structural change will be discussed.

  16. PROcess Based Diagnostics PROBE

    Science.gov (United States)

    Clune, T.; Schmidt, G.; Kuo, K.; Bauer, M.; Oloso, H.

    2013-01-01

    Many of the aspects of the climate system that are of the greatest interest (e.g., the sensitivity of the system to external forcings) are emergent properties that arise via the complex interplay between disparate processes. This is also true for climate models most diagnostics are not a function of an isolated portion of source code, but rather are affected by multiple components and procedures. Thus any model-observation mismatch is hard to attribute to any specific piece of code or imperfection in a specific model assumption. An alternative approach is to identify diagnostics that are more closely tied to specific processes -- implying that if a mismatch is found, it should be much easier to identify and address specific algorithmic choices that will improve the simulation. However, this approach requires looking at model output and observational data in a more sophisticated way than the more traditional production of monthly or annual mean quantities. The data must instead be filtered in time and space for examples of the specific process being targeted.We are developing a data analysis environment called PROcess-Based Explorer (PROBE) that seeks to enable efficient and systematic computation of process-based diagnostics on very large sets of data. In this environment, investigators can define arbitrarily complex filters and then seamlessly perform computations in parallel on the filtered output from their model. The same analysis can be performed on additional related data sets (e.g., reanalyses) thereby enabling routine comparisons between model and observational data. PROBE also incorporates workflow technology to automatically update computed diagnostics for subsequent executions of a model. In this presentation, we will discuss the design and current status of PROBE as well as share results from some preliminary use cases.

  17. Dual crystal scintillation probe

    International Nuclear Information System (INIS)

    A scintillation probe is described which employs two scintillation detectors having partially overlapping fields of view. The overlapping fields of view allow radioactive events from a particular spatial region to be identified and tabulated separately. Preferably, one crystal is annularly positioned with respect to the other and is collimated so that radioactive events from the left ventricle of the human heart can be isolated to a large extent from simultaneous background. Useful cardiac information is obtained in a non-invasive technique of medical examination of living patients requiring only a single injection of a radioisotope

  18. Mobile Probing Kit

    DEFF Research Database (Denmark)

    Larsen, Jakob Eg; Sørensen, Lene Tolstrup; Sørensen, J.K.;

    2007-01-01

    Mobile Probing Kit is a low tech and low cost methodology for obtaining inspiration and insights into user needs, requirements and ideas in the early phases of a system's development process. The methodology is developed to identify user needs, requirements and ideas among knowledge workers...... characterized as being highly nomadic and thus potential users of mobile and ubiquitous technologies. The methodology has been applied in the 1ST MAGNET Beyond project in order to obtain user needs and requirements in the process of developing pilot services. We report on the initial findings from applying this...

  19. Experimental probes of axions

    Energy Technology Data Exchange (ETDEWEB)

    Chou, Aaron S.; /Fermilab

    2009-10-01

    Experimental searches for axions or axion-like particles rely on semiclassical phenomena resulting from the postulated coupling of the axion to two photons. Sensitive probes of the extremely small coupling constant can be made by exploiting familiar, coherent electromagnetic laboratory techniques, including resonant enhancement of transitions using microwave and optical cavities, Bragg scattering, and coherent photon-axion oscillations. The axion beam may either be astrophysical in origin as in the case of dark matter axion searches and solar axion searches, or created in the laboratory from laser interactions with magnetic fields. This note is meant to be a sampling of recent experimental results.

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

    International Nuclear Information System (INIS)

    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)

  1. OBSERVATION OF ANISOTROPY IN THE ARRIVAL DIRECTIONS OF GALACTIC COSMIC RAYS AT MULTIPLE ANGULAR SCALES WITH IceCube

    International Nuclear Information System (INIS)

    Between 2009 May and 2010 May, the IceCube neutrino detector at the South Pole recorded 32 billion muons generated in air showers produced by cosmic rays with a median energy of 20 TeV. With a data set of this size, it is possible to probe the southern sky for per-mil anisotropy on all angular scales in the arrival direction distribution of cosmic rays. Applying a power spectrum analysis to the relative intensity map of the cosmic ray flux in the southern hemisphere, we show that the arrival direction distribution is not isotropic, but shows significant structure on several angular scales. In addition to previously reported large-scale structure in the form of a strong dipole and quadrupole, the data show small-scale structure on scales between 150 and 300. The skymap exhibits several localized regions of significant excess and deficit in cosmic ray intensity. The relative intensity of the smaller-scale structures is about a factor of five weaker than that of the dipole and quadrupole structure. The most significant structure, an excess localized at (right ascension α = 122.04 and declination δ = -47.04), extends over at least 200 in right ascension and has a post-trials significance of 5.3σ. The origin of this anisotropy is still unknown.

  2. Crustal anisotropy of Taihang Mountain Range using azimuthal variation of receiver functions

    Institute of Scientific and Technical Information of China (English)

    TIAN Bao-feng; LI Juan; YAO Zhen-xing

    2008-01-01

    We discussed the possibility of studying crust anisotropy by analyzing azimuthal variation of the receiver functions and presented a technique for computing the transmission response of a flat-layered medium with arbitrarily ori- ented hexagonally symmetric anisotropy using the reflectivity algorithm. Using this method we investigated the crust anisotropy of Taihang Mountain Range (TMR). Our result shows that there is significant anisotropy with a slow symmetry axis in the upper crust and a fast symmetry axis in the lower crust. The anisotropy magnitude of about 8%~15% is found in the upper crust and a smaller magnitude of about 3%~5% in the lower crust. Orienta- tion of the symmetry axes and the depth of anisotropy appearance as deduced from the seismic records of four individual seismic stations are different from each other. The crust anisotropy beneath the four stations may be associated with the local crustal fabrics in a small area.

  3. Uniaxial magnetic anisotropy of cobalt thin films on different substrates using CW-MOKE technique

    Energy Technology Data Exchange (ETDEWEB)

    Shukla, Vijay, E-mail: shuklavs@rrcat.gov.in [Laser Physics Applications Section, Raja Ramanna Centre for Advanced Technology, Indore 452013 (India); Mukherjee, C. [Mechanical and Optical Support Section, Raja Ramanna Centre for Advanced Technology, Indore 452013 (India); Chari, R. [Laser Physics Applications Section, Raja Ramanna Centre for Advanced Technology, Indore 452013 (India); Rai, S. [Indus Synchrotron Utilization Division, Raja Ramnna Centre for Advanced Technology, Indore 452013 (India); Bindra, K.S. [Solid State Laser Division, Raja Ramanna Centre for Advanced Technology, Indore 452013 (India); Banerjee, A. [BARC training school at RRCAT and Homi Bhabha National Institute, Raja Ramanna Centre for Advanced Technology, Indore 452013 (India)

    2014-12-15

    Cobalt thin films were deposited on GaAs, Si and Glass substrates by RF-magnetron sputtering. The structure was studied using atomic force microscopy, X-ray reflectivity and grazing incidence X-ray diffraction. Magnetic properties were determined with the magneto-optic Kerr effect. The deposited films have in-plane uniaxial anisotropy and after annealing the anisotropy reduces. The reduction in anisotropy may be due to release of stress and the remaining anisotropy after annealing may be due to shape anisotropy of the particulates. - Highlights: • Deposited cobalt thin films on different substrates and annealed at 300 °C. • Characterized as-grown and annealed films by GIXRD, AFM and MOKE. • Uniaxial magnetic anisotropy observed for all the samples. • Decrease in anisotropy on annealing may be due to release of stress during deposition.

  4. High Spatial Resolution Kelvin Probe Force Microscopy With Coaxial Probes

    OpenAIRE

    Westervelt, Robert M.; Brown, Keith A.; Satziner, 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...

  5. Electric field modulation of magnetic anisotropy and microwave absorption properties in Fe50Ni50/Teflon composite films

    Directory of Open Access Journals (Sweden)

    Zhenjun Xia

    2016-05-01

    Full Text Available Fe50Ni50 nanoparticle films with the size about 6 nm were deposited by a high energetic cluster deposition source. An electric field of about 0 - 40 kV was applied on the sample platform when the films were prepared. The field assisted deposition technique can dramatically induce in-plane magnetic anisotropy. To probe the microwave absorption properties, the Fe50Ni50 nanoparticles were deliberately deposited on the dielectric Teflon sheet. Then the laminated Fe50Ni50/Teflon composites were used to do reflection loss scan. The results prove that the application of electric field is an effective avenue to improve the GHz microwave absorption performance of our magnetic nanoparticles films expressed by the movement of reflection loss peak to high GHz region for the composites.

  6. Electric field modulation of magnetic anisotropy and microwave absorption properties in Fe50Ni50/Teflon composite films

    Science.gov (United States)

    Xia, Zhenjun; He, Jun; Ou, Xiulong; Wang, Yu; He, Shuli; Zhao, Dongliang; Yu, Guanghua

    2016-05-01

    Fe50Ni50 nanoparticle films with the size about 6 nm were deposited by a high energetic cluster deposition source. An electric field of about 0 - 40 kV was applied on the sample platform when the films were prepared. The field assisted deposition technique can dramatically induce in-plane magnetic anisotropy. To probe the microwave absorption properties, the Fe50Ni50 nanoparticles were deliberately deposited on the dielectric Teflon sheet. Then the laminated Fe50Ni50/Teflon composites were used to do reflection loss scan. The results prove that the application of electric field is an effective avenue to improve the GHz microwave absorption performance of our magnetic nanoparticles films expressed by the movement of reflection loss peak to high GHz region for the composites.

  7. Anisotropy of thermal infrared exitance in sunflower canopies

    Science.gov (United States)

    Tha Paw u, Kyaw; Ustin, Susan L.; Zhang, Chang-An

    1989-01-01

    Anisotropy of thermal infrared exitance above and within a relatively closed fully irrigated sunflower canopy is detailed. Azimuthal variation in thermal infrared exitance above canopies was weakly (statistically) related to solar position and was comparable to or larger than errors in satellite-based canopy estimates. Anisotropy within canopies was significantly lower and decreased with canopy closure and depth into the canopy. Measured azimuthal isotropy within canopies supports the use of this assumption in radiative transfer models. Significant differences in canopy temperature measurements were found depending upon whether the instruments were within or above the canopy. These differences could produce errors of 20-35 percent in latent energy estimates during periods of high evapotranspiration (ET) and greater errors in periods of restricted ET.

  8. Mechanical behaviour of ferritic ODS steels - Temperature dependancy and anisotropy

    Science.gov (United States)

    Fournier, B.; Steckmeyer, A.; Rouffie, A.-L.; Malaplate, J.; Garnier, J.; Ratti, M.; Wident, P.; Ziolek, L.; Tournie, I.; Rabeau, V.; Gentzbittel, J. M.; Kruml, T.; Kubena, I.

    2012-11-01

    Ferritic 14%Cr and 18%Cr ODS steels produced at CEA in round bars or plates were tested mechanically. The present paper reports results obtained in tension, impact, fatigue, creep and toughness tests. These tests were carried out at various temperatures and in different directions. These materials show a pronounced anisotropy at all tested temperatures. No matter the loading, the transversal direction is always found to be far less resistant than the longitudinal one. This anisotropy is mainly observed in terms of damage mechanisms, with intergranular fracture preferentially occurring along the extrusion direction. This intergranular fracture mode leads to very low and anisotropic toughness values and to the absence of tertiairy creep stage, pointing out the unstable nature of fracture, even at high temperature. The unrealistically high values of the Norton exponent measured in creep suggests the existence of a threshold stress, which is consistent with the mainly kinematic nature of the stress as revealed by fatigue tests.

  9. Lateral-drag Casimir forces induced by anisotropy

    CERN Document Server

    Nefedov, Igor S

    2016-01-01

    We predict the existence of lateral drag forces near the flat surface of an absorbing slab of an anisotropic material. The forces originate from the fluctuations of the electromagnetic field, when the anisotropy axis of the material forms a certain angle with the surface. In this situation, the spatial spectra of the fluctuating electromagnetic fields becomes asymmetric, different for positive and negative transverse wave vectors components. Differently from the case of van der Waals interactions in which the forward-backward symmetry is broken due to the particle movement or in quantum noncontact friction where it is caused by the mutual motion of the bodies, in our case the lateral motion results merely from the anisotropy of the slab. This new effect, of particular significance in hyperbolic materials, could be used for the manipulation of nanoparticles.

  10. Deciphering the Dipole Anisotropy of Galactic Cosmic Rays

    CERN Document Server

    Ahlers, Markus

    2016-01-01

    Recent measurements of the dipole anisotropy in the arrival directions of Galactic cosmic rays (CRs) indicate a strong energy dependence of the dipole amplitude and phase in the TeV-PeV range. We argue here that these observations can be well understood within standard diffusion theory as a combined effect of (i) one or more local sources at Galactic longitude 120deg < l < 300deg dominating the CR gradient below 0.1-0.3 PeV, (ii) the presence of a strong ordered magnetic field in our local environment, (iii) the relative motion of the solar system, and (iv) the limited reconstruction capabilities of ground-based observatories. We show that an excellent candidate of the local CR source responsible for the dipole anisotropy at 1-100 TeV is the Vela supernova remnant.

  11. Dynamical Condensation in a Holographic Superconductor Model with Anisotropy

    CERN Document Server

    Bai, Xiaojian; Park, Miok; Sunly, Khimphun

    2014-01-01

    We study dynamical condensation process in a holographic superconductor model with anisotropy. The time-dependent numerical solution is constructed for the Einstein-Maxwell-dilaton theory with complex scalar in asymptotic AdS spacetime. The introduction of dilaton field generates the anisotropy in boundary spatial directions. In analogy of isotropic case, we have two black hole solutions below certain critical temperature $T_c$, the anisotropic charged black hole with and without scalar hair, corresponding respectively to the supercooled normal phase and superconducting phase in the boundary theory. The instability of the supercooled anisotropic black hole will drive a small perturbation of the scalar field to rise exponentially, until the final stable hairy black hole configuration is reached. Via AdS/CFT correspondence, we extract time evolution of the condensate operator and anisotropic pressure of the boundary system. Both of them experience exponential growth and subsequent saturation, but with different...

  12. Monte Carlo simulations of medium-scale CMB anisotropy

    CERN Document Server

    Kogut, A J

    1996-01-01

    Recent detections of cosmic microwave background (CMB) anisotropy at half-degree angular scales show considerable scatter in the reported amplitude even at similar angular resolution. We use Monte Carlo techniques to simulate the current set of medium-scale CMB observations, including all relevant aspects of sky coverage and measurement technique. The scatter in the reported amplitudes is well within the range expected for the standard cold dark matter (CDM) cosmological model, and results primarily from the restricted sky coverage of each experiment. Within the context of standard CDM current observations of CMB anisotropy support the detection of a ``Doppler peak'' in the CMB power spectrum consistent with baryon density 0.01 < Omega_b < 0.13 (95% confidence) for Hubble constant H_0 = 50 km/s/Mpc. The uncertainties are approximately evenly divided between instrument noise and cosmic variance arising from the limited sky coverage.

  13. Structural Anisotropy in Polar Fluids Subjected to Periodic Boundary Conditions

    Science.gov (United States)

    2011-01-01

    A heuristic model based on dielectric continuum theory for the long-range solvation free energy of a dipolar system possessing periodic boundary conditions (PBCs) is presented. The predictions of the model are compared to simulation results for Stockmayer fluids simulated using three different cell geometries. The boundary effects induced by the PBCs are shown to lead to anisotropies in the apparent dielectric constant and the long-range solvation free energy of as much as 50%. However, the sum of all of the anisotropic energy contributions yields a value that is very close to the isotropic one derived from dielectric continuum theory, leading to a total system energy close to the dielectric value. It is finally shown that the leading-order contribution to the energetic and structural anisotropy is significantly smaller in the noncubic simulation cell geometries compared to when using a cubic simulation cell. PMID:22303290

  14. Large scale cosmic-ray anisotropy with KASCADE

    CERN Document Server

    Antoni, T; Badea, A F; Bekk, K; Bercuci, A; Blümer, H; Bozdog, H; Brancus, I M; Büttner, C; Daumiller, K; Doll, P; Engel, R; Engler, J; Fessler, F; Gils, H J; Glasstetter, R; Haungs, A; Heck, D; Hörandel, J R; Kampert, K H; Klages, H O; Maier, G; Mathes, H J; Mayer, H J; Milke, J; Müller, M; Obenland, R; Oehlschläger, J; Ostapchenko, S; Petcu, M; Rebel, H; Risse, A; Risse, M; Roth, M; Schatz, G; Schieler, H; Scholz, J; Thouw, T; Ulrich, H; Van, J; Buren; Vardanyan, A S; Weindl, A; Wochele, J; Zabierowski, J

    2004-01-01

    The results of an analysis of the large scale anisotropy of cosmic rays in the PeV range are presented. The Rayleigh formalism is applied to the right ascension distribution of extensive air showers measured by the KASCADE experiment.The data set contains about 10^8 extensive air showers in the energy range from 0.7 to 6 PeV. No hints for anisotropy are visible in the right ascension distributions in this energy range. This accounts for all showers as well as for subsets containing showers induced by predominantly light respectively heavy primary particles. Upper flux limits for Rayleigh amplitudes are determined to be between 10^-3 at 0.7 PeV and 10^-2 at 6 PeV primary energy.

  15. Nondestructive evaluation of plastic anisotropy in sheets with ultrasound

    International Nuclear Information System (INIS)

    According to the method of production the deep-drawing behavior of sheets more or less distinctly depends on the direction of rolling. It is generally descirbed by coefficients of anisotropy of the plastic behavior like R, r, Rsub(m) and ΔR. There are alternatives to this time-consuming and destructive method, like the X-ray texture image (nondestructive) or measurement of Young's modulus at specimens (i.e. taking of a sample). They are based on a correlation between elastic (texture) and plastic anisotropy. This paper describes a simple nondestructive method applied to the sheet itself: measurement of the directional dependence of the group velocity of guided ultrasonic waves. The positive results obtained up to now show that the method is appropriate for practical application. (orig.)

  16. TEXTURE ET ANISOTROPIE PLASTIQUE D'ALLIAGES AI-Li

    OpenAIRE

    MIZERA, Jaroslaw

    1993-01-01

    Le rôle spécifique des éléments d'alliage Li, Zr et Cu dans les alliages A1Li est déterminé en termes de leur influence sur l'évolution de la texture pendant un laminage et de leur incidence sur l'anisotropie plastique. Trois alliages modèles (Al-2,3% Li; Al-2,3% Li-0,1% Zr; Al-2,3%-1,2% Cu-0,1% Zr) sont lamines à chaud et à froid jusqu'à une réduction d'épaisseur de 92%. L'évolution de la texture et l'anisotropie des propriétés mécaniques de ces alliages sont caractérisées systématiquement a...

  17. Backscatter, anisotropy, and polarization of solar hard X-rays

    Science.gov (United States)

    Bai, T.; Ramaty, R.

    1978-01-01

    The problems of anisotropy, polarization, center-to-limb variation of the X-ray spectrum, and Compton backscatter are investigated in a study of solar hard X-rays. Effect of backscatter are found particularly important for anisotropic sources which emit hard X-rays predominantly toward the photosphere; for such anisotropic primary X-ray sources, the observed X-ray flux near 30 keV does not depend significantly on the position of the flare. In addition, the degree of polarization of the sum of the primary and reflected X-rays with energies in the 15 to 30 keV range may be as high as 30%. Determination of the height and anisotropy of the primary X-ray sources from study of the albedo patch is also discussed.

  18. Anisotropy Spectra for Enantiomeric Differentiation of Biomolecular Building Blocks

    DEFF Research Database (Denmark)

    Evans, Amanda C.; Meinert, Cornelia; Bredehoft, Jan H.;

    2013-01-01

    All biopolymers are composed of homochiral building blocks, and both D-sugars and L-amino acids uniquely constitute life on Earth. These monomers were originally enantiomerically differentiated under prebiotic conditions. Particular progress has recently been made in support of the photochemical...... model for this differentiation: the interaction of circularly polarized light with racemic molecules is currently thought to have been the original source for life’s biological homochirality. The differential asymmetric photoreactivity of particular small molecules can be characterized by both circular...... light. This chapter will: (1) present the theory and configuration of anisotropy spectroscopy; (2) explain experimentally recorded anisotropy spectra of selected chiral biomolecules such as amino acids; and (3) discuss the relevance of these spectra for the investigation of the origin of the molecular...

  19. Non-elliptic wavevector anisotropy for magnetohydrodynamic turbulence

    Science.gov (United States)

    Narita, Y.

    2015-11-01

    A model of non-elliptic wavevector anisotropy is developed for the inertial-range spectrum of magnetohydrodynamic turbulence and is presented in the two-dimensional wavevector domain spanning the directions parallel and perpendicular to the mean magnetic field. The non-elliptic model is a variation of the elliptic model with different scalings along the parallel and the perpendicular components of the wavevectors to the mean magnetic field. The non-elliptic anisotropy model reproduces the smooth transition of the power-law spectra from an index of -2 in the parallel projection with respect to the mean magnetic field to an index of -5/3 in the perpendicular projection observed in solar wind turbulence, and is as competitive as the critical balance model to explain the measured frequency spectra in the solar wind. The parameters in the non-elliptic spectrum model are compared with the solar wind observations.

  20. Magnetic anisotropy in EuS-PbS multilayers

    International Nuclear Information System (INIS)

    We present the results of ferromagnetic resonance studies of the thickness dependence of magnetic anisotropy in 2 series of EuS-PbS multilayers grown on (111) BaF2 and (100) KCl substrates with the EuS thickness varying in the range d = 6-70 A. The anisotropy constant K was found to follow the dependence K(d) = KV + 2KS/d, with the surface term KS larger for layers grown on BaF2 as compared to KCl.This difference is discussed in terms of different thermal stress-induced distortions of cubic crystal lattice of EuS. We found that the thickness of EuS layer required for the perpendicular (to the layer) magnetization is d ≤ 2-3 A, i,e., it is below 1 monolayer. (author)

  1. Optimization of artificial flockings by means of anisotropy measurements

    CERN Document Server

    Makiguchi, Motohiro

    2010-01-01

    An effective procedure to determine the optimal parameters appearing in artificial flockings is proposed in terms of optimization problems. We numerically examine genetic algorithms (GAs) to determine the optimal set of such parameters such as the weights for three essential interactions in BOIDS by Reynolds (1987) under `zero-collision' and `no-breaking-up' constraints. As a fitness function (the energy function) to be maximized by the GA, we choose the so-called the $\\textyen gamma$-value of anisotropy which can be observed empirically in typical flocks of starling. We confirm that the GA successfully finds the solution having a large $\\textyen gamma$-value leading-up to a strong anisotropy. The numerical experience shows that the procedure might enable us to make more realistic and efficient artificial flocking of starling even in our personal computers.

  2. Magnetic anisotropy of metal functionalized phthalocyanine 2D networks

    Science.gov (United States)

    Zhu, Guojun; Zhang, Yun; Xiao, Huaping; Cao, Juexian

    2016-06-01

    The magnetic anisotropy of metal including Cr, Mn, Fe, Co, Mo, Tc, Ru, Rh, W, Re, Os, Ir atoms functionalized phthalocyanine networks have been investigated with first-principles calculations. The magnetic moments can be expressed as 8-n μB with n the electronic number of outmost d shell in the transition metals. The huge magnetocrystalline anisotropy energy (MAE) is obtained by torque method. Especially, the MAE of Re functionalized phthalocyanine network is about 20 meV with an easy axis perpendicular to the plane of phthalocyanine network. The MAE is further manipulated by applying the external biaxial strain. It is found that the MAE is linear increasing with the external strain in the range of -2% to 2%. Our results indicate an effective approach to modulate the MAE for practical application.

  3. Edge anisotropy and the geometric perspective on flow networks

    CERN Document Server

    Molkenthin, Nora; Tupikina, Liubov; Marwan, Norbert; Donges, Jonathan F; Feudel, Ulrike; Kurths, Jürgen; Donner, Reik V

    2016-01-01

    Spatial networks have recently attracted great interest in various fields of research. While the traditional network-theoretic viewpoint is commonly restricted to their topological characteristics (often disregarding existing spatial constraints), this work takes a geometric perspective, which considers vertices and edges as objects in a metric space and quantifies the corresponding spatial distribution and alignment. For this purpose, we introduce the concept of edge anisotropy and define a class of measures characterizing the spatial directedness of connections. Specifically, we demonstrate that the local anisotropy of edges incident to a given vertex provides useful information about the local geometry of geophysical flows based on networks constructed from spatio-temporal data, which is complementary to topological characteristics of the same flow networks. Taken both structural and geometric viewpoints together can thus assist the identification of underlying flow structures from observations of scalar v...

  4. Controlling magnetic anisotropy in epitaxial FePt(001) films

    International Nuclear Information System (INIS)

    Epitaxial equiatomic Fe50Pt50 thin films with a variable order parameter ranging from 0 to 0.9 and Fe100-xPtx thin films with x ranging from 33 to 50 were deposited on MgO (001) substrates by dc sputtering. A seed layer consisting of nonmagnetic Cr (4 nm)/Pt (12 nm) was used to promote the crystallinity of the magnetic films. The crystal structure and magnetic properties were gauged using x-ray diffraction and magnetometry. The magnetic anisotropy can be controlled by changing the order parameter. For Fe100-xPtx films, the increase in Fe composition leads to an increase in coercivity in the hard axis loop and causes a loss of perpendicular anisotropy.

  5. Differential expansion of space and the Hubble flow anisotropy

    CERN Document Server

    Bolejko, Krzysztof; Wiltshire, David L

    2015-01-01

    The Universe on scales $10-100~h^{-1}$ Mpc is dominated by a cosmic web of voids, filaments, sheets and knots of galaxy clusters. These structures participate differently in the global expansion of the Universe: from non-expanding clusters to the above average expansion rate of voids. In this paper we characterize Hubble expansion anisotropies in the COMPOSITE sample of 4534 galaxies and clusters. We concentrate on the dipole and quadrupole in the rest frame of the Local Group. These both have statistically significant amplitudes. These anisotropies, and their redshift dependence, cannot be explained solely by a boost of the Local Group in the Friedmann-Lema\\^{i}tre-Robertson-Walker (FLRW) model which expands isotropically in the rest frame of the cosmic microwave background (CMB) radiation. We simulate the local expansion of the Universe with inhomogeneous Szekeres models, which match the standard FLRW model on $> 100~ h^{-1}$ Mpc scales but exhibit nonkinematic differential expansion on small scales. We res...

  6. Electron temperature anisotropy constraints in the solar wind

    Czech Academy of Sciences Publication Activity Database

    Štverák, Štěpán; Trávníček, Pavel M.; Maksimovic, M.; Marsch, E.; Fazakerley, A.; Scime, E. E.

    2008-01-01

    Roč. 113, A3 /2008/ (2008), A03103/1-A03103/10. ISSN 0148-0227 R&D Projects: GA AV ČR IAA300420602 Grant ostatní: EU(XE) ESA-PECS project No. 98024 Institutional research plan: CEZ:AV0Z10030501; CEZ:AV0Z30420517 Keywords : solar wind electrons * temperature anisotropy * radial Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 3.147, year: 2008

  7. A Coupled Multiscale Model of Texture Evolution and Plastic Anisotropy

    Science.gov (United States)

    Gawad, J.; Van Bael, A.; Yerra, S. K.; Samaey, G.; Van Houtte, P.; Roose, D.

    2010-06-01

    In this paper we present a multiscale model of a plastic deformation process in which the anisotropy of plastic properties is related to the evolution of the crystallographic texture. The model spans several length scales from the macroscopic deformation of the workpiece to the microscale interactions between individual grains in a polycrystalline material. The macroscopic behaviour of the material is described by means of a Finite Element (FE) model. Plastic anisotropy is taken into account in a constitutive law, based on the concept of a plastic potential in strain rate space. The coefficients of a sixth-order Facet equation are determined using the Taylor theory, provided that the current crystallographic texture at a given FE integration point is known. Texture evolution in the FE integration points is predicted by an ALAMEL micromechanical model. Mutual interactions between coarse and fine scale are inherent in the physics of the deformation process. These dependencies are taken into account by full bidirectional coupling in the model. Therefore, the plastic deformation influences the crystallographic texture and the evolution of the texture induces anisotropy of the macroscopic deformation. The presented approach enables an adaptive texture and yield surface update scheme with respect to the local plastic deformation in the FE integration points. Additionally, the computational cost related to the updates of the constitutive law is reduced by application of parallel computing techniques. Suitability of on-demand computing for this computational problem is discussed. The parallelisation strategy addresses both distributed memory and shared memory architectures. The cup drawing process has been simulated using the multiscale model outlined above. The discussion of results includes the analysis of the planar anisotropy in the cup and the influence of complex deformation path on texture development. Evolution of texture at selected material points is assessed as

  8. Alterations in white matter fractional anisotropy in subsyndromal perimenopausal depression

    OpenAIRE

    Wang, Xianglan; Tao, Jiong; Li, Lingjiang; Zhong, Zhiyong; Liu, Sha; Jiang, Tianzi; Zhang, Jinbei

    2014-01-01

    Background Subsyndromal depression (SSD) is considered as a predictor for future depressive disorders, however whether white matter abnormalities are involved in the high-susceptibility of women to depressive disorders during perimenopause is unknown. The purpose of this study was to investigate fractional anisotropy (FA) in the white matter of the whole brain in perimenopausal women with SSD using diffusion tensor imaging (DTI). Methods In a cross-sectional study, 24 perimenopausal women wit...

  9. Flow anisotropies due to momentum deposition from hard partons

    CERN Document Server

    Tomasik, Boris

    2015-01-01

    In nuclear collisions at the LHC large number of hard partons are created in initial partonic interactions, so that it is reasonable to suppose that they do not thermalise immediately but deposit their energy and momentum later into the evolving hot quark-gluon fluid. We show that this mechanism leads to contribution to flow anisotropies at all orders which are non-negligible and should be taken into account in realistic simulations.

  10. Light-controlled anisotropy in dielectrics containing azobenzene

    Czech Academy of Sciences Publication Activity Database

    Rais, David; Nešpůrek, Stanislav; Sedláková, Zdeňka; Zakrevskyy, Y.; Stumpe, J.

    Vol. Nr 982. Lodz : Department of Molecular Physics, Technical University of Lodz, 2006 - (Socha, A.), s. 270-271 ISSN 0458-1555. [Conference International Dielectric Society /4./ and International Conference Dielectric and Related Phenomena /9./. Poznan (PL), 03.09.2006-07.09.2006] R&D Projects: GA AV ČR IAA4112401 Institutional research plan: CEZ:AV0Z40500505 Keywords : azobenzene * light anisotropy * photochromism Subject RIV: CD - Macromolecular Chemistry

  11. Structural Anisotropy in Polar Fluids Subjected to Periodic Boundary Conditions

    OpenAIRE

    Stenhammar, Joakim; Karlström, Gunnar; Linse, Per

    2011-01-01

    A heuristic model based on dielectric continuum theory for the long-range solvation free energy of a dipolar system possessing periodic boundary conditions (PBCs) is presented. The predictions of the model are compared to simulation results for Stockmayer fluids simulated using three different cell geometries. The boundary effects induced by the PBCs are shown to lead to anisotropies in the apparent dielectric constant and the long-range solvation free energy of as much as 50%. However, the s...

  12. Multi-region relaxed magnetohydrodynamics with anisotropy and flow

    OpenAIRE

    Dennis, Graham R.; Hudson, Stuart R.; Dewar, Robert L.; Hole, Matthew J.

    2014-01-01

    We present an extension of the multi-region relaxed magnetohydrodynamics (MRxMHD) equilibrium model that includes pressure anisotropy and general plasma flows. This anisotropic extension to our previous isotropic model is motivated by Sun and Finn's model of relaxed anisotropic magnetohydrodynamic equilibria. We prove that as the number of plasma regions becomes infinite, our anisotropic extension of MRxMHD reduces to anisotropic ideal MHD with flow. The continuously nested flux surface limit...

  13. Soliton collisions in soft magnetic nanotube with uniaxial anisotropy

    OpenAIRE

    Usov, N. A.

    2016-01-01

    The structure of stable magnetic solitons of various orders in soft magnetic nanotube with uniaxial magnetic anisotropy has been studied using numerical simulation. Solitons of even order are immobile in axially applied magnetic field. Odd solitons show decreased mobility with respect to that of head-to head domain wall. Solitons of various orders can participate in nanotube magnetization reversal process. Various coalescence and decomposition processes in soliton assembly are considered. It ...

  14. Simulation of erasure of photoinduced anisotropy by circularly polarized light

    DEFF Research Database (Denmark)

    Sajti, Sz.; Kerekes, Á.; Barabás, M.; Lorincz, E; Hvilsted, Søren; Ramanujam, P.S.

    The temporal evolution of photoinduced birefringence is investigated on the basis of a model proposed by Pedersen and co-workers, This model is extended for the case of elliptically polarized light, and used to describe the erasure of photoinduced birefringence by circularly polarized light. It i...... shown that the anisotropy is not erased, only the direction of the optical axis is changed, and this is measured as erasure. The computed results are compared with measurements and show good agreement for several intensities....

  15. Electric Field Controlled Magnetic Anisotropy in a Single Molecule

    OpenAIRE

    Zyazin, Alexander S.; Berg, Johan W. G. van den; Osorio, Edgar A; Van Der Zant, Herre S J; Konstantinidis, Nikolaos P.; Leijnse, Martin; Wegewijs, Maarten R; May, Falk; Hofstetter, Walter; Danieli, Chiara; Cornia, Andrea

    2010-01-01

    We have measured quantum transport through an individual Fe$_4$ single-molecule magnet embedded in a three-terminal device geometry. The characteristic zero-field splittings of adjacent charge states and their magnetic field evolution are observed in inelastic tunneling spectroscopy. We demonstrate that the molecule retains its magnetic properties, and moreover, that the magnetic anisotropy is significantly enhanced by reversible electron addition / subtraction controlled with the gate voltag...

  16. The Yuan-Tseh Lee Array for Microwave Background Anisotropy

    OpenAIRE

    Ho, Paul T. P.; Altamirano, Pablo; Chang, Chia-Hao; Chang, Shu-Hao; Chang, Su-Wei; Chen, Chung-Cheng; Chen, Ke-Jung; Chen, Ming-Tang; Han, Chih-Chiang; Ho, West M.; Huang, Yau-De; Hwang, Yuh-Jing; Ibanez-Romano, Fabiola; Jiang, Homin; Koch, Patrick M.

    2008-01-01

    The Yuan-Tseh Lee Array for Microwave Background Anisotropy (AMiBA) is the first interferometer dedicated to studying the cosmic microwave background (CMB) radiation at 3mm wavelength. The choice of 3mm was made to minimize the contributions from foreground synchrotron radiation and Galactic dust emission. The initial configuration of seven 0.6m telescopes mounted on a 6-m hexapod platform was dedicated in October 2006 on Mauna Loa, Hawaii. Scientific operations began with the detection of a ...

  17. Elastic anisotropy changes of granulites due to their thermal heating

    Czech Academy of Sciences Publication Activity Database

    Lokajíček, Tomáš; Rudajev, Vladimír; Dwivedi, R.

    Prague : Institute of Geology , Academy of Sciences of the Czech Republic, v. v. i, 2011 - (Rudajev, V.; Živor, R.). s. 17-17 ISBN 978-80-87443-04-0. [Polish-Czech-Slovak Symposium on Mining and Environmental Geophysics /33./. 19.09.2011-22.09.2011, Staré Splavy] Institutional research plan: CEZ:AV0Z30130516 Keywords : elastic anisotropy * ultrasonic sounding * granulite * rock heating Subject RIV: DC - Siesmology, Volcanology, Earth Structure

  18. Seismic anisotropy below Mexico and its implications for mantle dynamics

    OpenAIRE

    Stubailo, Igor

    2015-01-01

    We use data from seismic networks with unprecedented dense coverage to study the Earth's structure under Mexico. First, we develop a three-dimensional (3-D) model of shear-wave velocity and anisotropy for the Mexico subduction zone using fundamental mode Rayleigh wave phase velocity dispersion measurements. The 3-D nature of our surface-wave-based results allows for better understanding of the interaction between the subducting slab, mantle lithosphere, and asthenosphere in the top 200 km. ...

  19. Conductivity anisotropy of layered BiTe-SbTe-heterostructures

    International Nuclear Information System (INIS)

    Transport properties of ordered bismuth and antimony tellurides are studied theoretically based on first-principle electronic structure calculations using a screened Korringa-Kohn-Rostoker Greens function method. The anisotropy of the electron mobility both in the bulk materials and in layered BiTe-SbTe-heterostructures is analyzed within the relaxation time approximation of the Boltzmann theory. The influence of doping on the electrical conductivity is discussed applying the rigid band approximation.

  20. Conductivity anisotropy of layered BiTe-SbTe-heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Yavorsky, Bogdan; Hinsche, Nicki; Zahn, Peter [Martin-Luther-Universitaet Halle-Wittenberg, Institut fuer Physik, Halle (Germany); Gradhand, Martin; Mertig, Ingrid [Martin-Luther-Universitaet Halle-Wittenberg, Institut fuer Physik, Halle (Germany); MPI fuer Mikrostrukturphysik, Halle (Germany)

    2010-07-01

    Transport properties of ordered bismuth and antimony tellurides are studied theoretically based on first-principle electronic structure calculations using a screened Korringa-Kohn-Rostoker Greens function method. The anisotropy of the electron mobility both in the bulk materials and in layered BiTe-SbTe-heterostructures is analyzed within the relaxation time approximation of the Boltzmann theory. The influence of doping on the electrical conductivity is discussed applying the rigid band approximation.