bluuebunny/crossref_metadata_2025 huggingface dataset:
Early cretaceous absolute geomagnetic paleointensities from Córdoba Province (Argentina)
Authors: Ruiz Ruben Cejudo , Goguitchaichvili Avto , Geuna Silvana E. , Alva-Valdivia Luis M. , Solé Jesus , Morales Juan
Published: August 2014

We present here new paleointensity and geochronology results from Early Cretaceous volcanic rocks of Sierra Chica de Cordoba (Argentina). The new K-Ar isotopic ages of 5 samples range from 136 to 122 Ma. Twenty five samples from 7 individual flows yielded acceptable paleointensity estimates. The mean paleointensity values per flow are ranging from 53.0 ± 1.9 to 25.4 ± 2.6 μT and the corresponding Virtual Dipole Moments (VDMs) are ranging from 9.3±1.3 to 4.6±0.5 (1022 Am2). This corresponds to the mean value of 7.3±1.7×1022 Am2, which is compatible to the present geomagnetic axial dipole. Currently available selected paleointensity data from 80 to 130 Ma suggest that geomagnetic field strength frequently fluctuated before and during the Cretaceous Normal Superchron while the magnetic polarity maintained stable. The mean paleointensities derived from Córdoba lavas agree remarkably well with those obtained from the Paraná Magmatic Province (133–132 Ma). This reinforces the hypothesis about the unreliability of ‘Mesozoic Dipole Low’. Key words: Paleointensity, rock-magnetism, Early Cretaceous, South America.
Rock magnetic study of fluvial Holocene soil from Buenos Aires province (Argentina)
Authors: Vasquez Carlos A. , Nami Hugo G.
Published: August 2014

The magnetic characteristics of soils are widely used in environmental and paleoclimatic investigations for studying the several factors involved in the soil formation process. We propose here a new analytical tool that takes into account the variations in magnetic properties correlated with grain sizes and concentrations of ferrimagnetic minerals. This analytical tool is based on a mathematical model of well-established magnetic properties in samples of known grain sizes and was used in this study to determine changes in the grain size and concentration of ferrimagnetic minerals along a terminal Pleistocene/Holocene fluvial section located in the northeast of Buenos Aires province. These variations may reflect a humid period prevailing in the area and may be associated with climate changes that occurred in the Chaco-Pampean region during the Middle Holocene.
Estimations of the S-wave velocity structures in Chia-Yi City, Taiwan, using the array records of microtremors
Authors: Huang Huey-Chu , Wu Cheng-Feng
Published: August 2014

Shear-wave velocities (VS) have been widely used for the site characterization of earthquake ground motion. We report here our investigation of theS-wave velocity structures of Chia-Yi City, Taiwan using the array records of microtremors at seven sites. The dispersion curves at these sites were first calculated using the F-K method proposed by Capon (1969); theS-wave velocity structures in Chia-Yi City were then estimated by employing the surface wave inversion technique (Herrmann, 1991). At frequencies lower than about 1 Hz, the propagation directions are concentrated in the northwest and southwest quadrants. The generation of these may be attributed to the ocean waves of the Taiwan Strait. The harder site (CBA) has higher phase velocities, while the softer sites (CWB, SHP and YRU) have lower phase velocities, especially at frequencies between 1 and 5 Hz. The shallow velocity structures (0–1,500 m) can be roughly divided into four to five layers. The depth of the alluvium gradually increases from east to west and from north to south.
Sq and sfe currents at equatorial stations along the western and eastern African sectors
Authors: Rastogi R. G.
Published: August 2014

The paper describes the daily variations in the Sq and sfe induced ionospheric current at the equatorial stations of Addis-Ababa (Inclination: 1.0°; Declination: 1.5°) and M’Bour (Inclination: 9.0°; Declination: −9.3°). At Addis-Ababa, the diurnal SqH loop as well as sfe H currents aligned fairly well with the direction of declination. At M’Bour, the SqH as well as the sfe H vector were along the direction of about 30°W. Thus, in the region of an abnormally large declination at equatorial stations, the daily Sq current does not follow a direction normal to the declination.
Hypocenter distribution of the main- and aftershocks of the 2005 Off Miyagi Prefecture earthquake located by ocean bottom seismographic data
Authors: Hino Ryota , Yamamoto Yojiro , Kuwano Asako , Nishino Minoru , Kanazawa Toshihiko , Yamada Tomoaki , Nakahigashi Kazuo , Mochizuki Kimihiro , Shinohara Masanao , Minato Kouetsu , Aoki Gen , Okawara Nariaki , Tanaka Masayuki , Abe Masao , Araki Eiichiro , Kodaira Shuichi , Fujie Gou , Kaneda Yoshiyuki
Published: August 2014

The preliminary hypocenter distribution of the 2005 Off Miyagi Prefecture earthquake and its aftershocks is estimated using data from five ocean bottom and six onshore seismic stations located around the rupture area of the earthquake. The epicenter of the mainshock is relocated at 38.17°N, 142.18°E, and the focal depth is estimated to be 37.5 km. The aftershocks surrounding the mainshock hypocenter form several clusters that are concentrated along a distinct landward dipping plane corresponding to the plate boundary imaged by the previous seismic experiment. The strike and dip angles of the plane agree well with those of the focal mechanism solution of the mainshock. The size of the plane is about 20×25 km2 in the strike and dip directions, which is similar to that of the large coseismic slip area. The up-dip end of the planar distribution of the aftershocks corresponds to the bending point of the subducting oceanic plate, suggesting that the geometry of the plate boundary affects the spatial extent of the asperity of the 2005 earthquake
Source modeling of the 2005 off-shore Miyagi prefecture, Japan, earthquake (MJMA=7.2) using the empirical Green’s function method
Authors: Kamae K.
Published: August 2014

A preliminary source model composed of asperities for the 2005 off-shore Miyagi prefecture, Japan, earthquake (MJMA=7.2) was estimated by the empirical Green’s function method. The source parameters for two asperities located on the fault plane were determined by comparing synthesized broad-band ground motions with observed ones at several stations. We concluded that the stress parameters of the asperities are very high (90 MPa for Asp-1,300 MPa for Asp-2) and that these values are nearly equal to those (73 MPa and 29 MPa) calculated by the Earthquake Research Committee (2005) in Japan for the off-shore Miyagi prefecture earthquake that is expected in the near future. However, the location of the asperities is not completely consistent with the expected event.
Imaging S-wave scatterer distribution in southeast part of the focal area of the 2005 West Off Fukuoka Prefecture Earthquake (MJMA 7.0) by dense seismic array
Authors: Matsumoto Satoshi , Watanabe Atsushi , Matsushima Takeshi , Miyamachi Hiroki , Hirano Syuichiro
Published: August 2014

Spatial distribution of S-wave scatterers in the SE part of the focal area of the 2005 West Off Fukuoka Prefecture Earthquake (M = 7.0) has been estimated using dense seismic array data. Waveforms of 22 natural earthquakes were analyzed in a frequency range of 16–24 Hz. It is difficult to estimate the inhomogeneous structure in this wavelength range with ordinary travel time tomography despite the importance of this parameter for understanding the earthquake-generating process. After filtering and gain recovery in the coda part, observed waveforms were semblance-enhanced slant-stacked into various directions from the array. This was followed by diffraction curve summation in order to image the scatterer distribution. The spatial distribution of scatterers thus imaged revealed that higher strengths were distributed at the SE-extension of the fault plane of the event, which corresponds to a region where the rupture process of the main shock stopped
Crustal structure of the southwestern margin of the Kuril arc sited in the eastern part of Hokkaido, Japan, inferred from seismic refraction/reflection experiments
Authors: Kurashimo Eiji , Iwasaki Takaya , Hirata Naoshi , Ito Tanio , Kaneda Yoshiyuki
Published: August 2014

Hokkaido Island in northern Japan is located at the intersection of the Kuril and Northeast Japan arcs. Eastern Hokkaido represents the southwestern margin of the Kuril arc that evolved as an oceanic island arc, but its crustal structure has remained unclarified. In the summer of 2000, a highly dense onshore-offshore integrated seismic experiment was conducted in order to reveal the entire crustal section covering from the Kuril Trench to the back-arc basin of the Okhotsk Sea crossing eastern Hokkaido. High-quality refraction/wide-angle reflection data collected for the onshore survey line delineated a detailed crustal structure of easternmost part of Hokkaido Island. Our seismic velocity model shows a good correlation with the surface geology along the profile. The notable feature of the velocity model is the existence of a 6.0-km/s layer beneath the onshore survey line. A reflective middle to lower crust is also found beneath eastern Hokkaido. These results indicate that the southwestern margin of the Kuril arc is in a matured state of oceanic island-arc crust.
An example of secondary fault activity along the North Anatolian Fault on the NE Marmara Sea Shelf, NW Turkey
Authors: Tur Huseyin
Published: August 2014

Seismic data on the NE Marmara Sea Shelf indicate that a NNE-SSW-oriented buried basin and ridge system exist on the sub-marine extension of the Paleozoic Rocks delimited by the northern segment of the North Anatolian Fault (NS-NAF), while seismic and multi-beam bathymetric data imply that four NW-SE-oriented strike-slip faults also exist on the shelf area. Seismic data indicate that NW-SE-oriented strike-slip faults are the youngest structures that dissect the basin-ridge system. One of the NW-SE-oriented faults (F1) is aligned with a rupture of the North Anatolian Fault (NAF) cutting the northern slope of the Ç0imarc0ik Basin. This observation indicates that these faults have similar characteristics with the NS-NAF along the Marmara Sea. Therefore, they may have a secondary relation to the NAF since the principle deformation zone of the NAF follows the Marmara Trough in that region. The seismic energy recorded on these secondary faults is much less than that on the NAF in the Marmara Sea. These faults may, however, produce a large earthquake in the long term.
On long-term trends in European geomagnetic observatory biases
Authors: Verbanac Giuli , Korte Monika , Mandea Mioara
Published: August 2014

We investigated the European geomagnetic observatory biases over 42 years, considered as contributions of the crustal field, and generally assumed to be constant in time. To estimate these biases, we compared observatory annual means to predictions given by the continuous CM4 model, and to four other core field models for different epochs. Solar-cycle related external fields are clearly present in the residuals. Although well-known, no suitable model to minimise them exists. We found that an empirical approach, taking advantage of the homogeneity of the external influences in the European region, can minimise these influences. Their reduction is better than when the external field description included in the comprehensive CM4 model is used. At several locations clear long-term trends remain after subtraction of the core field and minimisation of external fields. We investigated whether they are due to an insufficient description of the core field secular variation by the CM4 model, or to changes in induced lithospheric fields.
Site amplification and strong ground motion of the 2007 Noto Hanto, Japan, earthquake estimated from aftershock observation
Authors: Yoshimi Masayuki , Yoshida Kunikazu
Published: August 2014

Site amplifications in the lowlands most affected by the 2007 Noto Hanto earthquake, Monzen, Anamizu, and Wajima, are examined using aftershock records observed at eight temporary seismic stations installed just after the mainshock and at two K-NET stations. The predominant frequencies of spectral ratios at alluvium sites in Anamizu and Wajima are approximately 1 Hz. Site amplifications at the alluvium sites are successfully reproduced from 1-D response analysis, except for that at ISK005 where 2-D or higher amplification effects are inferred to play a significant role. A source model composed of two asperities reproduces the ground motions of the mainshock using the empirical Green’s function method. The seismic moments of the asperities are 3.76×1018N m and 2.21×1018N m, respectively. Peak ground velocity (PGV) at alluvium sites during the mainshock are estimated to be 70–110 cm/s for Monzen, 50–110 cm/s for Anamizu, and 60–70 cm/s for Wajima.
Estimation of the lunar reflectance by ground-based observation using a tunable liquid-crystal filter telescope
Authors: Saiki Kazuto , Saito Kimiko , Okuno Hideaki , Suzuki Akiko , Yamanoi Yuta , Hirata Naru , Nakamura Ryosuke
Published: August 2014

Lunar reflectance data are useful not only for lithological identification of the lunar surface but also for radiometric calibration and determination of exposure time for optical sensors of lunar probes. To gain data on lunar reflectance, we acquired multi-band images (five bands: 650, 750, 900, 950, and 1000 nm) of the lunar surface and those of some standard stars using a liquid-crystal tunable filter (LCTF) telescope located on the peak of Mt. Haleakala (Hawaii, USA). The data obtained indicate that the reflectance data of Clementine UV/VIS is too high and that the correction factor is 0.59±0.06 at 950 nm. Our new reflectance data are available to the public at the web site of one of authors (K.S.). We report here our method of deriving the lunar reflectance images from the ground-based observation with a hyperspectral telescope for the users of our reflectance data. The results suggest that ground-based observation is more suitable for the radiometric calibration of the sensor of a lunar probe than laboratory data.
Displacement analysis of the GPS station of Sampali, Indonesia
Authors: Lee Eun Soo , Lee Young Wook , Park Jung Hyun
Published: August 2014

The displacement of the SAMP GPS station located in Medan City, Indonesia, is analyzed by means of an on-line point positioning method, the Canadian Spatial Reference System-Precise Point Positioning (CSRS-PPP). Based on the comparison of the results obtained with those from previous studies, we propose that CSRS-PPP can be applied to analyses of the displacement of a GPS station. Previous studies have focused solely on the “Sumatra-Andaman Islands Earthquake of December 26, 2004”; in contrast, we provide here an in-depth analysis of the crustal movements at the SAMP station for an expanded period of 2.5 years. CSRS-PPP, an Internet data processing service of the Department of Natural Resources Canada (NRCan), was used to process the data obtained at the SAMP station from January 2004 to July 2006. The data show a clear displacement in the southwestern direction from December 26, 2004 to March 28, 2005 when two major earthquakes occurred. However, after the midpoint of 2005, the data show displacement at a regular speed. In particular, the “Sumatra-Andaman Islands Earthquake (M
w = 9.0) of December 26, 2004” led to a displacement of 0.1387 m (dn = −0.0122 m, de = −0.1382 m) to the southwest. The earthquake (M
w = 8.7) that occurred on March 28, 2005 led to a displacement of 0.1921 m (dn = −0.1400 m, de = −0.1315 m) to the southwest. Starting from December 26, 2004, displacement to the southwest continued. From April 2005, however, the speed of the displacement gradually slowed down. The dn variation shows a displacement at a regular rate (−55.69 mm/year) from April 28, 2005 to July 2006, while the de variation shows a displacement at a regular rate (−23.66 mm/year) from July 5, 2005 to July 2006.
Evaluation of dehydration mechanism during heating of hydrous asteroids based on mineralogical and chemical analysis of naturally and experimentally heated CM chondrites
Authors: Nakato Aiko , Nakamura Tomoki , Kitajima Fumio , Noguchi Takaaki
Published: August 2014

Based on the evidence derived from spectroscopic observation and meteorite analysis, some hydrous asteroids were heated and dehydrated for a certain period of time after aqueous alteration. In order to reproduce the dehydration processes, we experimentally heated Murchison CM chondrite at 600°C for 1 h (600°C/1 h), 600°C/96 h, 900°C/1 h, and 900°C/96 h under controlled oxygen partial pressures. The experimental products were compared with Belgica (B-)7904 CM chondrite, a meteorite from a dehydrated asteroid in terms of characteristic mineralogical and compositional properties. B-7904 shows properties intermediate between the two experimental products heated at 900°C/1 h and 900°C/96 h. In addition, the presence or the absence of some temperature-sensitive minerals in B-7904 suggests that it experienced heating at a temperature higher than 700°C but lower than 890°C. The duration of heating, based on the diffusion time needed to achieve the Fe-Mg zoning profile in olivine in B-7904, was estimated to be between 10 and 103 days at 700°C and between 1 to 102 h at 890°C. The obtained durations are much shorter than those expected from the internal heating model which requires prolonged heating over million years. Therefore, it is unlikely that the short-lived radionuclide of 26Al is a heat source for the dehydration of B-7904. Instead, short-duration local heating, such as that from impacts or solar radiation, is a more promising heat source.
Latitudinal dependence of the solar wind density derived from remote sensing measurements using interplanetary Lyman α emission from 1999 to 2002
Authors: Nakagawa Hiromu , Fukunishi Hiroshi , Watanabe Shigeto , Takahashi Yukihiro , Taguchi Makoto , Lallement Rosine
Published: August 2014

The interplanetary Lyman α backscattered emission is an effective tool for remote sensing of the global structure of the solar wind proton flux. This paper reports an attempt to derive the latitudinal dependence of the solar wind density by combining the interplanetary Lyman α measurements of the Nozomi spacecraft for the period 1999–2002 with the solar wind speed data derived from interplanetary scintillation measurements. This approach successfully revealed the slow and dense solar wind over the poles during the period of the solar maximum. Data on the polar solar wind density indicate a significant growth from the middle of 2000, and the polar values of solar wind density are close to those of the equatorial values as a result of the disappearance of the coronal hole. A marked density depletion occurred in the middle of 2001, which can be ascribed to the development of fast winds from the polar coronal hole. To evaluate the remote sensing method, we considered solar wind density data from in situ measurements obtained by the Ulysses spacecraft. We conclude that our method basically agrees with in situ measurements, although we found a significant (a factor of 2) difference between these in the middle of 2001.
Three dimensional configuration of earthward fast plasma flow in the near-Earth plasma sheet
Authors: Kondoh Koji , Ugai Masayuki , Shimizu Tohru
Published: August 2014

The earthward short-term (1-min. order) fast flow event (Flow Burst) and the long-term (10-min. order) fast flow event (Bursty Bulk Flow) observed in the near-Earth plasma sheet are examined using three dimensional MHD simulations on the basis of spontaneous fast reconnection model. It is well known that these fast flow events are closely related to the magnetic substorms. On the other hand, it is considered that these fast flow events are caused by the magnetic reconnection in the near-Earth magnetotail. The time profiles of plasma quantities in these events observed by in-situ satellites are quite different in each event. Above Flow Burst and Bursty Bulk Flow events are often examined separately due to the large difference in time scale. In this paper, these differences are interpreted by the three-dimensional position of satellite relative to the X-line and the reconnection jet channel, and the simulation results are directly compared with the results of in-situ satellite observations using the virtual satellites located in simulation domain.
Frequency-dependent attenuation of S-waves in the Kanto region, Japan
Authors: Yoshimoto Kazuo , Okada Mariko
Published: August 2014

Apparent, scattering, and intrinsicS-wave attenuations (QS−1,Qscat−1andQint−1) of the upper lithosphere in the Kanto region of Japan were measured in the 1- to 32-Hz frequency range using Multiple Lapse Time Window Analysis (MLTWA) for 115 borehole seismograms of local earthquakes. A new set of time windows for MLTWA, in which multiple isotropic scattering is assumed, was proposed and employed to estimate the frequency dependence ofS-wave attenuation parameters. Scattering attenuation was found to dominate intrinsic attenuation in theS-wave attenuation mechanism at low frequencies (<;2 Hz), whereas the opposite relation was observed at high frequencies. The transition is caused by the different frequency dependences ofQscat−1(∝f−1.5) andQint−1(∝f−0.7) at this frequency. Interestingly,Qscat−1is almost frequency independent at frequencies >8 Hz, which implies the self-similar nature of short-wavelength heterogeneities in the upper lithosphere. In terms of the upper lithosphere of the Kanto region, these results may indicate that the random heterogeneities characterized by the Gaussian autocorrelation function with a fractional fluctuationε≈ 10% and a correlation lengtha≈ 2 km are superimposed on the weak background self-similar heterogeneity.
Prehistorical archaeomagnetic directions from Hungary in comparison with those from south-eastern Europe
Authors: Márton P.
Published: August 2014

Since the beginning of the modern archaeomagnetic investigations in Hungary in the nineteen seventies, some directional data of various prehistorical ages have also accumulated beside a larger body of the historical results. These are presented here and compared with 1) coeval directional results which are available from south-eastern Europe, as well as 2) the predictions of geomagnetic field directions for Hungary of the global geomagnetic field model, CALS7K.2. The comparison with the south-eastern European data has lead to new archaeomagnetic dates for one of the studied archaeological features which are thought to be an improvement to the presently accepted radiometric dates.
An analysis of the infrasound signal from the Miyagi-Oki earthquake in Japan on 16 August 2005
Authors: Che Il-Young , Lee Hee-Il , Jeon Jeong-Soo , Kang Tae-Seob
Published: August 2014

Following the 16 August 2005 Miyagi-Oki earthquake in Japan, coherent atmospheric infrasonic waves were observed at regional distances (1200–1500 km) using three seismo-acoustic arrays on the Korean Peninsula. A source-location procedure was applied to the distinct long-duration infrasonic signals to construct earthquakegenerated infrasound source regions on the Japanese island arc. The results showed that the long-duration infrasonic signal was attributable to extensive seismic ground motions on land areas from the southwestern through to the northeastern part of the island arc as well as regions close to the earthquake epicenter. In many coherent infrasonic signals, an effect of seismic ground motions in sedimentary basins could be identified as a source of infrasound radiation from the large earthquake. These observations and interpretations were confirmed using predictions of possible infrasound arrival azimuth variation by converting real seismological data from the dense Japanese seismic network.
Variation process in stiffness inferred by nonlinear inversion during mainshocks at Kushiro Port vertical array site
Authors: Thabet Mostafa , Nemoto Hiroo , Nakagawa Koichi
Published: August 2014

In the present study, a set of three strong motions accompanied by 21 before and after mainshock motions from liquefied soil at the Kushiro Port vertical array site have been obtained.S-wave velocity variation is estimated using a new proposed nonlinear GA inversion technique. This inversion technique is reproductive in assessment forS-wave velocities due to its direct link with the simulation FEM program and matching technique between the observed and simulated waveforms. Layers (6 ∼ 23 m depth) have been found to be responsible for liquefaction at the Kushiro Port site. Stiffness degradation due to liquefaction could be predicted by applying the inversion technique on the horizontal components of the mainshocks at different time-windows and then multiplying the weighting functions by the nonlinear simulated ground motions. These weighting functions were applied to delete the misfit time window of the nonlinear simulated ground motions when these were compared to the observed records. Finally, stacking was applied for the weighted nonlinear simulated ground motions. A strong degree of liquefaction is concluded during the Kushiro-Oki (1993) and the Hokkaido Toho-Oki (1994) earthquakes, whereas a low degree of liquefaction was detected to have occurred during the Tokachi-Oki (2003) earthquake due to high increase of rigidity following a trend that resembles a consolidation curve.
Substorm onset dynamics in the magnetotail as derived from joint TC-1 and Cluster data analysis
Authors: Wang H. , Lühr H. , Ma S. Y. , Ridley A. J.
Published: August 2014

This study investigates two substorm onset events with favorable constellations of spacecraft, TC-1 and Cluster, separated by several Earth radii. The substorms have been identified in both auroral regions. One is believed to be triggered by a northward turning of the interplanetary magnetic field (IMF), while the other occurs under generally southward IMF. For both events, Cluster was located tailward of TC-1, but observed the dipolarization at earlier time for one event while at later time for the other. The timing difference of dipolarization at different positions could be explained by the earthward or tailward propagation of the field disturbances in the radial direction. The earthward dipolarization front was found in one case to bounce back and forth at TC-1. The earthward propagation was accompanied by a fast earthward plasma flow for the 21 September 2005 event. The event analysis suggests that substorms can be quite different from case to case due to differences in the solar wind condition and magnetotail configuration.
Postseismic slip associated with the 2007 Chuetsu-oki, Niigata, Japan, Earthquake (M 6.8 on 16 July 2007) as inferred from GPS data
Authors: Iinuma Takeshi , Ohta Yusaku , Miura Satoshi , Tachibana Kenji , Matsushima Takeshi , Takahashi Hiroaki , Sagiya Takeshi , Ito Takeo , Miyazaki Shin’ichi , Doke Ryosuke , Takeuchi Akira , Miyao Kayo , Hirao Akihiko , Maeda Takahiro , Yamaguchi Teruhiro , Takada Masamitsu , Iwakuni Makiko , Ochi Tadafumi , Meilano Irwan , Hasegawa Akira
Published: August 2014

Postseismic crustal deformation associated with the 2007 Chuetsu-oki Earthquake, which occurred on 16 July 2007 with a magnitude of 6.8 at the southeastern rim of the Sea of Japan, near the coast of Mid-Niigata Prefecture, Central Japan, are detected by GPS observations. We analyzed continuous GPS data from the sites of the Geographical Survey Institute of Japan (GSI) and another dense temporary network, which we established just after the main shock to reveal spatio-temporal evolution of postseismic slip for 50 days after the main shock by geodetic inversion methods. Four models of faults are configured following Ohtaet al.(2008, this issue), and these are optimized based on ABIC (Akaike’s Bayesian Information Criterion). The results of the inversion analysis show that the postseismic slip on the faults occurred at a downdip and updip extension of the coseismically slipped portion. The slip in the shallower portion decayed to be negligible within 2 weeks, and the slip in the deeper portion was still large after the slip in the shallower portion had almost terminated.
Electrodynamics of the vertical coupling processes in the atmosphere-ionosphere system of the low latitude region
Authors: Abdu M. A. , Brum C. G. M.
Published: August 2014

Dynamical, electro-dynamical and electrical coupling processes originating from upward propagation of atmospheric waves, and magnetosphere-ionosphere interaction are responsible for the large degree of variabilities observed in the low latitude ionosphere. One of the most outstanding aspects of its phenomenology is related to the sunset electrodynamical processes responsible for the evening enhancements in zonal and vertical electric fields and the associated spread of F/plasma bubble irregularity development. Recent observational results have provided evidence of significant contribution to their quiet time variability arising from thermospheric wind patterns, upward propagating planetary waves and possibly sporadic E layers. This paper provides an overview and some new results on planetary wave coupling with the equatorial F region, the E layer conductivity as key connecting mechanism, a possibly interactive role by sporadic E layers, and the resulting day-to-day variability in the evening prereversal electric field enhancements with consequences on spread F development.
Reflection and refraction of acoustic waves at poroelastic ocean bed
Authors: Vashishth A. K. , Sharma M. D.
Published: August 2014

Ocean bottom is considered as a plane interface between non-viscous liquid and anisotropic dissipative poroelastic solid. The dissipation comes from the viscosity of pore-fluid as well as the anelasticity of the porous frame. Biot’s theory is used to derive a system of modified Christoffel equations for the propagation of plane harmonic waves in a porous medium. The non-trivial solution of this system is ensured by a determinantal equation. This equation is solved into a polynomial equation of degree eight, whose roots represent the vertical slowness values for the waves propagating upward and downward in a porous medium. The eight, numerically obtained, slowness values are identified with the four waves propagating towards (or away from) the boundary in the porous medium. Incidence of acoustic wave through the liquid at the interface results in its reflection and the refraction of four attenuating waves in the poroelastic medium. The energy partition among the reflected and refracted waves is calculated at the interface. Conservation of energy is obtained except in the case of partially opened surface pores of the porous medium. Energy refracted to the dissipative porous medium is expressed through an energy matrix. The four diagonal elements of this matrix represent the energy shares of the four inhomogeneous waves and the sum of all the off-diagonal elements of this matrix represents the interaction energy. Few significant results are extracted from the observations in the numerical examples studied. These results represent the effect of anisotropic symmetries, anelasticity, wave-frequency, opening, configuration and flow-impedance of pores, on the energy shares of reflected and refracted waves.
Multi-year temperature measurements of the middle atmosphere at Chatanika, Alaska (65°N, 147°W)
Authors: Thurairajah Brentha , Collins Richard L. , Mizutani Kohei
Published: August 2014

Over an eight-year period (1997–2005) Rayleigh lidar temperature measurements of the stratosphere and mesosphere (40–80 km) have been made at Poker Flat Research Range, Chatanika, Alaska (65°N, 147°W). The Rayleigh lidar measurements have been made between mid-August and mid-May. These measurements have yielded a total of approximately 904 hours of temperature measurements of the middle atmosphere over 116 nights. The seasonal evolution of the middle atmosphere shows an annual cycle with maximum in summer below 60 km and a reversal of the cycle with minimum in summer above 60 km. The monthly mean stratopause has a highest temperature of 273 K at an altitude of 47.5 km in May and a lowest temperature of 243 K at an altitude of 54.7 km in January. However, nightly stratopause temperatures in January and December are sometimes warmer than those in May and August. An elevated stratopause (>65 km) is observed on 5 occasions in 41 observations in January and February. The Chatanika measurements are compared with five other Arctic data sets and models. The upper stratosphere at this site is slightly colder than the zonal mean as well as sites in Greenland and Scandinavia with the largest differences found in January. We discuss the wintertime temperatures in the upper stratosphere and lower mesosphere in terms of the position of the polar vortex and the increased occurrence of stratospheric warming events during the 1997–2005 observation period.
A new instrument for the study of wave-particle interactions in space: One-chip Wave-Particle Interaction Analyzer
Authors: Fukuhara Hajime , Kojima Hirotsugu , Ueda Yoshikatsu , Omura Yoshiharu , Katoh Yuto , Yamakawa Hiroshi
Published: August 2014

Wave-particle interactions in a collisionless plasma have been analyzed in several past space science missions but direct and quantitative measurement of the interactions has not been conducted. We here introduce the Wave-Particle Interaction Analyzer (WPIA) to observe wave-particle interactions directly by calculating the inner product between the electric field of plasma waves and of plasma particles. The WPIA has four fundamental functions: waveform calibration, coordinate transformation, time correction, and interaction calculation. We demonstrate the feasibility of One-chip WPIA (O-WPIA) using a Field Programmable Gate Array (FPGA) as a test model for future science missions. The O-WPIA is capable of real-time processing with low power consumption. We validate the performance of the O-WPIA including determination of errors in the calibration and power consumption.
Application of GOCE data for regional gravity field modeling
Authors: Janák Juraj , Fukuda Yoichi , Xu Peiliang
Published: August 2014

In principle, every component of a disturbing gravity gradient tensor measured in a satellite orbit can be used to obtain gravity anomalies on the Earth’s surface. Consequently, these can be used in combination with ground or marine data for further gravity field modeling or for verification of satellite data. Theoretical relations can be derived both in spectral and spatial forms. In this paper, we focus on the derivation of a spatial integral form in the geocentric spherical coordinates that seems to be the most convenient one for regional gravity field modeling. All of the second partial derivatives of the generalized Stokes’s kernel are derived, and six surface Fredholm integral equations are formulated and discretized. The inverse problems formulated for particular components clearly reveal different behaviors in terms of numerical stability of the solution. Simulated GOCE data disturbed with Gaussian noise are used to study the performance of two regularization methods: truncated singular value decomposition and ridge regression. The optimal ridge regression method shows slightly better results in terms of the root mean squared deviation of the differences from the exact solution.
The effect of distribution of stations upon location error: Statistical tests based on the double-difference earthquake location algorithm and the bootstrap method
Authors: Bai Ling , Wu Zhongliang , Zhang Tianzhong , Kawasaki Ichiro
Published: August 2014

In this letter, we investigate the effect of station distribution (including the number and azimuthal gap of stations) upon location error based on the field data observed at Northern California Seismic Network (NCSN) using a double-difference earthquake location algorithm and a bootstrap method. The earthquakes relocated by all 117 stations are set as reference and the error of location is defined as the RMS of the difference to the reference. We find that the location error has a nonlinear relationship with the distribution of stations. The results may be used as guidelines for building seismic network.
Mass-redistribution-induced crustal deformation of global satellite laser ranging stations due to non-tidal ocean and land water circulation
Authors: Takiguchi Hiroshi , Otsubo Toshimichi , Fukuda Yoichi
Published: August 2014

The effect of the non-tidal ocean load (NTOL) and the continental water load (CWL) on crustal deformation are calculated for global satellite laser ranging (SLR) stations and on 4°×4° grids (only over the land). For the regions most severely affected, the peak-to-peak displacements due to the NTOL are found to be as large as 3 mm for the horizontal components and 10 mm for the vertical component. The peak-to-peak displacements due to the CWL reach 3 mm for the horizontal components and 15 mm for the vertical component. We apply the time series of NTOL and CWL to precise SLR analysis. The LAGEOS orbit analysis reveals that the Estimating the Circulation and Climate of the Ocean (ECCO) model makes the root mean square (RMS) of the range residual 0.2% smaller, and that the CWL makes it 0.8% smaller, compared with the case where loading displacement is neglected. On the other hand, with the NTOL derived from Topex/Poseidon altimetry data, the SLR orbit fit is not improved.
Context-aware recommender for mobile learners
Authors: Benlamri Rachid , Zhang Xiaoyun
Published: August 2014

As mobile technologies become widespread, new challenges are facing the research community to develop lightweight learning services adapted to the learner’s profile, context, and task at hand. This paper attempts to solve some of these challenges by proposing a knowledge-driven recommender for mobile learning on the Semantic Web. The contribution of this work is an approach for context integration and aggregation using an upper ontology space and a unified reasoning mechanism to adapt the learning sequence and the learning content based on the learner’s activity, background, used technology, and surrounding environment. Whenever context change occurs, the system identifies the new contextual features and translates them into new adaptation constraints in the operating environment. The proposed system has been implemented and tested on various mobile devices. The experimental results show many learning scenarios to demonstrate the usefulness of the system in practice.
Synthesis and characterization of macrocyclic poly(.-methylstyrene)
Authors: Dong Dahai , Hogen-Esch Thieo E.
Published: August 2014

The synthesis is described of macrocyclic poly(α-methylstyrene) (PAMS) by the lithium naphthalide initiated polymerization of AMS followed by high dilution end to end coupling with 1,4-bis(bromomethyl)benzene (DBX). The cyclization is carried out by simultaneous addition of tetrahydrofuran solutions of the PAMS dianion and DBX at about -100ºC. A sample of the matching linear PAMS is obtained by protonation of the PAMS dianion. The purified cycles are obtained by fractional precipitation that is monitored by size exclusion chromatograhy. A careful study of the coupling reactions carried out at high concentrations indicates that coupling is efficient and this is borne out by the ratios () of apparent molecular weights (MW’s) of cycles and matching linear polymers. The  values of the cycles tend to vary with MW in the same manner as was demonstrated for polystyrene and other vinyl polymers and increase from around 0.74 at MW of about 30000 to values of around 0.82 at MW of about 2500. A higher apparent  value was observed for a very low MW PAMS but this sample could not be purified and analyzed adequately. As was also observed for other macrocyclic vinylpolymers, the glass transition temperatures of the cycles are MW independent above MW of about 5000 but decrease sharply at lower MW’s.
Polyzwitterionic aqueous solutions – a new class of electrorheological fluids
Authors: Georgiev George S. , Tzoneva Anna A. , Spassov Velin A.
Published: August 2014

It has been established that the electroviscosity effect of polyzwitterionic (PZI) aqueous solutions is more considerable than and acts in a direction opposite to that of aqueous polyelectrolyte solutions. Temperature and electric field strength influence the electroviscosity of PZI aqueous solutions in parallel, though the reasons for these effects are quite different. The unusual electroviscosity behaviour of PZI solutions is explained by a ‘core-shell’ model for the structural organization of PZI macromolecules, suggesting that cluster formation is due to intensive dipoledipole interactions between monomer units of the same or of different macromolecules.
Photoluminescence and electroluminescence of mono- and dialkyl-substituted soluble polythiophenes
Authors: Angiolini Luigi , Salatelli Elisabetta , Bolognesi Alberto , Botta Chiara
Published: August 2014

We report a comparison between optical properties (photoluminescence and UV-Vis absorption) and electroluminescence in a series of soluble polyalkylthiophenes with the aim of better understanding the role of different structural parameters, viz. length of side chains and introduction of unsubstituted thiophenes and their position in the backbone, on the electro-optical properties. The potential of these polymers as material for an active film in a single layer light emitting diode is evaluated.
Towards polymer-inorganic hybrid molecular composites: calorimetric studies of the polymer-inorganic particles interaction
Authors: Penczek Stanislaw , Kaluzynski Krzysztof , Pretula Julia , Bartczak Zbigniew , Zielenkiewicz Wojciech , Kaminski Miron
Published: August 2014

Inorganic particles of 3 CaO ⋅ SiO2 were reacted in water dispersion with dihydrophilic ionic-nonionic block copolymers, and the heat effect of interaction was measured by calorimetry. The ionic block was constituted of monoesters of phosphoric acid or alkyl phosphonic acid, both built on the polyglycidol block, attached to the poly(ethylene oxide) block. The heat evolved during the interaction is a function of the degree of phosphorylation (phosphonylation). The higher the degree of -OH substitution the stronger the interaction, the latter being stronger for phosphates than for phosphonates.
Chain expansion and chain localisation in the homogenous regime of blends of liquid low molar mass polysiloxanes as revealed by neutron scattering investigations
Authors: Götz Heide , Ewen Bernd , Maschke Ulrich , Monkenbusch Michael , Meier Gerd
Published: August 2014

Using small angle neutron scattering and neutron spin echo spectroscopy, two isotopic blends of low molar mass polydimethylsiloxane (PDMS) and polyethylmethylsiloxane (PEMS), and the corresponding binary blends d-PDMS/ p-PEMS and p-PDMS/d-PEMS (d: deuterated, p: protonated) were studied at the critical composition in the homogeneous regime. From the scattering data it becomes evident that coil dimensions and collective dynamics of these both blend systems behave significantly different. Compared to the isotopic mixtures, which exhibit the expected unperturbed chain dimensions and the typical Rouse relaxation, in the binary blends, which differ by a large shift with respect to the critical temperature, considerable coil expansion and spatially restricted Rouse relaxation occur. Both these structural and dynamic effects are in agreement with the model of droplet formation and chain localization, resulting from the existence of microscopic heterogeneities within the spinodal boundaries of the phase diagram. In addition, the observation of Rouse relaxation, spatially restricted to microscopic length scales, provides a new access to the molecular understanding of the critical slowing down of the mutual diffusion process, observed by photon correlation spectroscopy.
31P NMR measurement of the homolysis rate constant of the C-ON bond of β-phosphorylated alkoxyamines
Authors: Bertin Denis , Gigmes Didier , Marque Sylvain , Tordo Paul
Published: August 2014

In the presence of an excess of various alkyl radical scavengers or nitroxide reductants (TEMPO, phenylhydrazine and thiophenol), 31P NMR monitoring was used to determine the homolysis rate constant (kd) of β-phosphorylated alkoxyamines. The kd values for a mixture of diastereoisomeric alkoxyamines can be obtained in a single experiment and the formation of reaction products can be followed. The measured values were in good agreement with those obtained with other approaches involving chromatography or electron paramagnetic resonance (EPR).
Novel photosensitive polyurethanes based on photochromic dithienylethene monomers: synthesis, characterization and photophysical properties of a new film-building material for photonic applications
Authors: Bens Arthur Thomas , Comanici Radu , Gabel Bianca , Kryschi Carola , Martin Hans-Dieter , Ritter Helmut
Published: August 2014

The synthesis of a novel photochromic dithienylethene-based polyurethane and its characterization by optical spectroscopy and scanning tunneling microscopy are presented. This linear polyurethane builds up perfect free-standing films suited for photonic applications. Moreover it may be extruded to long mechanically stable fibers. The photochromic reactions of the polyurethane, as being the electrocyclic ring-closure and ring-opening reactions of the dithienylethene unit in the polymer backbone, occur in a completely reversible and highly efficient fashion.
Impact modification of polyamide-12 through blending with liquid polybutadiene, 3 a Properties of compatibilized blends of PA12 and liquid polybutadiene
Authors: Talon Olivier , Couvercelle Jean-Pierre , Bunel Claude
Published: August 2014

Blends of polyamide 12 (PA12) and liquid polybutadiene (HTPB) compatibilized with pyromellitic anhydride (APy) were prepared by melt blending. 10%, 12% and 20% HTPB blends were prepared, with various amounts of APy. The influence of the amount of APy on the morphology of the blends was studied for a wide composition range in the 12% series. Injection moulded tensile and Charpy testing bars were prepared from 10% and 20% binary and compatibilized blends. The deformations of the matrix under room temperature impact and the morphology of the blends were investigated with scanning electron microscopy. Partial miscibilization of HTPB with PA12 due to the addition of APy was postulated to explain the disappearance of polybutadiene in some cases. The mechanical properties of the blends were correlated with morphological parameters. A strong correlation between impact fracture toughness and the amount of non-miscible HTPB was found.
Approach to observe folded chains of syndiotactic polystyrene on solution-grown crystals by atomic force microscopy
Authors: Suto Nobuyuki , Fujimori Atsuhiro , Masuko Toru
Published: August 2014

Folded chains of syndiotactic polystyrene located on the surface of its solution-grown crystals (SGCs) have been observed on nano scale by use of atomic force microscopy (AFM). Transmission electron micrographs of the SGCs on the mesoscopic scale exhibited truncated-lozenge platelets accompanied by a sharp electron diffraction pattern of the β”-form. AFM images of selected areas on the SGC surface indicated folded chains existing periodically on the surface with c. 1.3 to 1.4 nm spacing, suggesting that the polymer chains are aligned in parallel with the {230} growth faces of SGC.
Atom transfer radical polymerization of styrene initiated by the novel initiator N-bromosuccinimide
Authors: Zhang Wei , Zhu Xiulin , Zhu Jian
Published: August 2014

Heterogeneous atom transfer radical polymerization of styrene initiated by N-bromosuccinimide in bulk was successfully carried out with CuBr/2,2’-bipyridine as the catalyst. The kinetics follow first order in monomer and molecular weights (polydispersities Mw/Mn = 1.23 - 1.66) increase linearly with monomer conversion, indicating the ‘living’/controlled nature of the polymerization. However, the number-average molecular weights were usually higher than the theoretical ones. That demonstrates the relatively low efficiency of the initiator, the causes of which are discussed. The obtained polystyrenes functionalized with α-α-pyrrolidine- 2,5-dionyl and ω-Br as the end groups were characterized by 1H NMR spectroscopy. They can be used as macroinitiators for chain extension reaction. A polymerization mechanism for this novel initiation system is proposed.