bluuebunny/crossref_metadata_2025_split huggingface dataset:
Berthierine and chamosite hydrothermal: genetic guides in the Peña Colorada magnetite-bearing ore deposit, Mexico
Authors: Rivas-Sanchez M. L. , Alva-Valdivia L. M. , Arenas-Alatorre J. , Urrutia-Fucugauchi J. , Ruiz-Sandoval M. , Ramos-Molina M. A. 
Published: August 2014

Abstract
We report the first finding of berthierine and chamosite in Mexico. They occur in the iron-ore deposit of Peña Colorada, Colima. Their genetic characteristics show two different mineralization events associated mainly to the magnetite ore. Berthierine is an Fe-rich and Mg-low 1:1 layer phyllosilicate of hydrothermal sedimentary origin. Its structure is 7 Å, d
hkl [10 0] basal spacing and low degree structural ordering. The phyllosilicate has been identified by a lack of 14 Å basal reflection on X-ray diffraction (XRD) patterns. These data were supported by High Resolution Transmision Electron Microscopy (HRTEM) images that show thick packets of berthierine in well defined parallel plates. From the analysis of Fast Fourier Transform (FFT), we found around [1 0 0] reflections of berhierine 7.12 Å and corresponding angles of hexagonal crystalline structure. Berthierine has a microcrystalline structure, dark green color, and high refraction index (1.64 to 1.65). Birefringence is low, near 0.007 to null and it is associated to nanoparticles (<15 nm) and microparticles of magnetite (<25 μm), fine grain siderite, and organic matter. Its texture is intergranular-interstratified with colloform banding. The chamosite Mg-rich is of hydrothermal epigenetic origin affected by low-degree metamorphism. It is an Fe-rich 2:1 layer silicate, with basal space of 14 Å, d
hkl [0 0 1]. The chamosite occurs as lamellar in sizes ranging from 50 to 150 μm. It has intense green color and refraction index from 1.64 to 1.65. The birefringence is near 0.008, with biaxial (-) orientation and a 2V small. It is associated mainly to sericite, epidote, clay, feldspar, and magnetite. Chamosite is emplaced in open spaces filling and linings. Mössbauer spectra of berthierine and chamosite are similar. They show the typical spectra of paramagnetic substances, with two well defined unfoldings corresponding to the oxidation state of Fe+2 and Fe+3. Chemical composition of both minerals was obtained by an electron probe X-ray micro-analyzer (EPMA). The radio Fe+Mg+Mn vs Si and Al show similar chemical compositions and different XRD patterns in the crystalline structure provoked by the environmental conditions of emplacement. A hydrothermal environment was predominant, occurring before, during, and after the magnetite mineralization. The identification of magnetite nanoparticles supports the hypothesis of a marine environment, specifically exhalative sedimentary (SEDEX) for the berthierine.
Coexistence of cosmic-ray sidereal anisotropies originating in galactic space and at the heliomagnetospheric nose and tail boundaries, observed with muon detectors in the energy region of 60∼100 GeV
Authors: Nagashima K. , Fujii Z. 
Published: August 2014

Abstract
The coexistence of two kinds of cosmic-ray sidereal anisotropy was found by observations with underground muon telescopes in the energy region (> ∼200 GeV) in 1995: one is the galactic anisotropy with a deficit flux in the direction with right ascension α

G
= 12 hr and declination δ

G
= 20°. The other is the excess flux from the heliomagnetospheric tail direction (α

T
≃ 6 hr) and would be produced on the heliotail boundary where it is considered that the interaction between the galactic and solar magnetic fields could produce the cosmic-ray acceleration. On the other hand, another anisotropy of helioboundary origin from the helionose direction (α ≃ 18 hr), being accompanied by the heliotail-in anisotropy, was found through the observations with neutron monitors in the low energy region (∼20 GeV) in 2005. These observations, however, lack information in the mid-energy region (20∼200 GeV). In order to bridge the absence of information, the cosmic-ray sidereal daily variations in the energy regions (60∼100 GeV) have been derived from the observations with muon telescopes and ion chambers on the ground in the period 1936–2003. It is shown that all the three anisotropies coexist in this energy region and are subject to their respective solar modulations. On the basis of these modulations, the characteristics of the anisotropies are determined through intercomparison with the observations in the high and low energy regions.
Variations in the equatorial ionization anomaly peaks in the Western Pacific region during the geomagnetic storms of April 6 and July 15, 2000
Authors: Lin Chien-Hung , Liu Jann-Yenq , Tsai Ho-Fang , Cheng Chio-Zong 
Published: August 2014

Abstract
This study utilizes total electron content (TEC) observed by a network of ground-based GPS receivers located in the Western Pacific region (∼120°E) to study the responses of the low-latitude equatorial ionization anomaly (EIA) to the two major magnetic storms that occurred during April 4–10 and July 12–18, 2000. The latitude, time, and TEC (LTT) maps in the northern and southern EIA regions show that both EIA peaks move equatorward along with a pronounced reduction of the TEC values 10–12 h after the storm onset. The variations in the EIA peak TEC values and locations in the northern EIA are highly correlated with those in the southern EIA. The correlation coefficients of the day-to-day variations of peaked TEC between the northern and southern EIA regions are 0.75 in the April storm and 0.83 in the July storm. The correlation coefficients of the day-to-day EIA peak movements between the two hemispheres are 0.98 in the April storm event and 0.88 in the July storm event. The highly correlated peaked TEC and movements between the northern and the southern hemisphere suggest that the storm-produced electrodynamics played a dominant role in affecting the low-latitude ionosphere during the two major storms.
Day-to-day variability of the equatorial electrojet current in the South American sector
Authors: Rastogi R. G. 
Published: August 2014

Abstract
A comparison of the geomagnetic H field data at Ancon, Peru and Buriticupa, Brazil for the period December 1990 and January 1991 revealed the presence of a significant correlation in day-to-day variability in the solar daily variation of H at the two stations, which are separated by about 2000 km. It is suggested that the day-to-day variability in the time as well as in the magnitude of the daily peak of the H field at an equatorial electrojet station is due to the superimposition of a semi-diurnal wave of the electric field over the normal mean daily variation.
The behaviour and detection of partial thermoremanent magnetisation (PTRM) tails in Thellier palaeointensity experiments
Authors: Biggin Andrew J. , Perrin Mireille 
Published: August 2014

Abstract
We analyse the results of Thellier palaeointensity experiments modified so that the measured magnetisation at any stage may be decomposed into components of natural remanent magnetisation (NRM) and laboratory thermal remanent magnetisation (TRM). We demonstrate that the very long high temperature tails of pTRM acquired by multidomain (MD) grains may be detected in Thellier experiments without recourse to explicit pTRM tail check measurements. This can save time in the experimental process and provides a more sensitive indication of how MD behaviour may affect that particular experiment than either pTRM tail checks or the observation of zigzagging in an IZZI experiment. We observe that the action of imparting a pTRM tail also involves some removal of NRM. However, the pTRM tails are not the analogues of classical overprints as may be intuitively expected but instead appear to favour remagnetisation over demagnetisation. This and other observed behaviour is not consistent with any phenomenological model of MD TRM but is consistent with predictions made by kinematic theory.
New K-Ar ages of the Society Islands, French Polynesia, and implications for the Society hotspot feature
Authors: Uto K. , Yamamoto Y. , Sudo M. , Uchiumi S. , Ishizuka O. , Kogiso T. , Tsunakawa H. 
Published: August 2014

Abstract
We report 52 new K-Ar age determinations of volcanic rocks from the Society Islands in French Polynesia. The newly obtained ages range from 0.51 to 4.61 Ma, which are consistent with previously reported ones. The magnetostratigraphy based on 45 data sets combining K-Ar ages and paleomagnetic polarity agrees with the geomagnetic polarity time scale at the 2s level, except for a few age data. Assuming the absolute motion of the Pacific plate, paleopositions of the dated rocks are estimated from the K-Ar ages, showing a narrow distribution in the western part of the easternmost volcano of the active hotspot region. This suggests that a hotspot of a few tens of kilometers in diameter might have been fixed nearly at the eastern margin of the presently active region in the Society archipelago and that the volcanism of each island might have persisted for about 1 myr.
Searching satellites of asteroid Itokawa by imaging observation with Hayabusa spacecraft
Authors: Fuse Tetsuharu , Yoshida Fumi , Tholen David , Ishiguro Masateru , Saito Jun 
Published: August 2014

Abstract
We carried out a search for satellites around Itokawa, the target asteroid of the Japanese Hayabusa mission. An imaging instrument, AMICA, on the spacecraft was used to take four images of Itokawa and its vicinity on September 1, 2005. The distance of the spacecraft from Itokawa was approximately 1,700 km, somewhat longer than the original plan (1,000 km) due to the mission schedule. The field-of-view of AMICA corresponded to 170 km × 170 km around Itokawa. Since the Hill sphere of Itokawa was estimated to be 33 km at the time of the observations, the images completely covered the detectable area of satellites. However, we cannot find the motion of Itokawa satellites between the four images, because the observation period was set to 2 hr due to the mission schedule and the region where satellites would be observable was only within 8 km of Itokawa, which is inside the extensive glare of Itokawa on the images. In addition, high-energy protons produced by a huge solar flare impacted the spacecraft during the observations, and hence the four images suffered from many random spots. Comparing the positions of the spots with catalogued stars, we managed to identify stellar images. No evidence of satellites was found. Additionally, we evaluated the 1-m detection limit of the images from the limiting magnitude of 9.5. The absence of satellites of Itokawa is consistent with past optical and radar observations as well as other results by the Hayabusa spacecraft.
Deep Impact and sample return
Authors: A’Hearn Michael F. , Belton Michael J. S. , Collins Steven M. , Farnham Tony L. , Feaga Lori M. , Groussin Olivier , Lisse Carey M. , Meech Karen J. , Schultz Peter H. , Sunshine Jessica M. 
Published: August 2014

Abstract
Returning a cold sample containing the ices from a cometary nucleus has long been an unachievable goal of cometary scientists. The results from the Deep Impact encounter with comet Tempel 1 suggest that the task is much easier than previously thought. Thus a cold sample return with ice becomes an achievable goal, at least from comet Tempel 1 and plausibly from other, active Jupiter-family comets.
Asteroids and the origin of life—two steps of chemical evolution on the surface of these objects
Authors: Simakov M. B. 
Published: August 2014

Abstract
It is now well-known that carbonaceous chondrites contain large quantities of prebiotic molecules, including amino acids, carbohydrates, and heterocyclic bases of nucleic acids. It has become evident that the chemical evolution proceeds under conditions of open space, which serves as a huge chemical reactor. The extraterrestrial origin of these prebiotic molecules has been established on the basis of diversity, molecular structure, and isotopic composition. The molecular composition of a meteorite’s organics resembles abiotic processes governed by physico-chemical processes that occurred on the parent bodies, including asteroids. The synthesis of soluble compounds in carbonaceous chondrites consists of a multi-step process in which organic precursors were formed in the interstellar cloud, incorporated with many volatiles into icy planetesimals and, upon aqueous processing produced the variety of compounds which can form complexes under space energy sources. We show experimentally that the solid mixtures of biologically significant compounds (nucleosides and amino acids) produce more complex compounds when they are exposed to either vacuum UV photons or ionizing radiation.
Performance and scientific objectives of the SELENE (KAGUYA) Multiband Imager
Authors: Ohtake Makiko , Haruyama Junichi , Matsunaga Tsuneo , Yokota Yasuhiro , Morota Tomokatsu , Honda Chikatoshi ,   LISM team
Published: August 2014

Abstract
The Multiband Imager (MI) is one of the 14 instruments for the Japanese SELENE (KAGUYA) mission. Goal of the SELENE (KAGUYA) mission is to understand origin and evolution of the Moon by obtaining global element and mineral compositions, topological structure, gravity field of the whole Moon, and electromagnetic and particle environment of the Moon. MI is designed to be a high-resolution multiband imaging camera with a spatial resolution in visible bands of 20 m and a spatial resolution in near-infrared bands of 62 m from the 100 km SELENE (KAGUYA) orbit altitude. The MI flight model has been manufactured and integrated. MTF, viewing vector, over-all sensibility, sensor linearity and electrical noise level (S/N estimation test) were measured, and the results indicate that the MI will provide sufficient MTF and low-noise data, just as estimated in the MI design phase. Operation and data analyses plans have been established, and related tools and algorithms have been developed and checked. One of MI scientific objectives is to investigate small but scientifically very important areas such as crater central peaks and crater walls and to investigate magnesian anorthosites.
Numerical estimation of lunar X-ray emission for X-ray spectrometer onboard SELENE
Authors: Ogawa Kazunori , Okada Tatsuaki , Shirai Kei , Kato Manabu 
Published: August 2014

Abstract
We conducted a numerical estimation of lunar X-ray spectra, which is applicable for lunar X-ray fluorescence observations using an X-ray spectrometer (XRS) onboard the SELENE orbiter, with an improved simulation model. We investigated the integration times of measurements for six elements (Mg, Al, Si, Ca, Ti, and Fe) to achieve signal-to-background ratio of over 10 under various solar conditions. The results of these calculations indicate that expected along-the-track spatial resolutions of a single orbital path for Mg, Al and Si will be <90 km and 20 km under normal and active Sun conditions, respectively. Ca, Ti and Fe will be also detectable with a spatial resolution of 20 km during the periods active solar flares over M1 class happen to occur.
The possibility of studying the lunar ionosphere with the SELENE radio science experiment
Authors: Imamura Takeshi , Oyama Koh-Ichiro , Iwata Takahiro , Kono Yusuke , Matsumoto Koji , Liu Qinghui , Noda Hirotomo , Futaana Yoshifumi , Nabatov Alexander 
Published: August 2014

Abstract
The electron density profiles above the lunar surface will be observed by the radio occultation technique during the SELENE mission using the Vstar sub-satellite. Previous radio occultation observations have indicated the existence of an ionosphere with densities of up to 1000 cm−3 above the dayside lunar surface. The measured densities are difficult to explain theoretically when the removal of plasma by the solar wind is considered, and thus the generation mechanism of the lunar ionosphere is a major issue, with even the validity of previous observations still under debate. The SELENE radio science experiment will establish the morphology of the lunar ionosphere and will reveal its relationship with various physical conditions to provide possible clues to the mechanism.
Effects of interactions between stations on the calculation of geomagnetically induced currents in an electric power transmission system
Authors: Pirjola Risto 
Published: August 2014

Abstract
“Geomagnetically induced currents” (GIC) in ground-based technological networks are a manifestation of space weather. GIC are a potential source of problems to the systems and therefore important in practice. GIC in a power system (or in principle in any other discretely-earthed system) can be calculated conveniently by using matrix equations presented earlier. Since temporal variations associated with GIC are slow compared to the 50/60 Hz frequency used in power transmission, a dc treatment is acceptable. An essential quantity in calculations of GIC in a power grid is the earthing impedance matrix, which is the transfer function coupling GIC flowing to (from) the Earth with the voltages between the earthing points, called nodes or (sub)stations, and a remote earth. The diagonal elements of the matrix equal the earthing resistances of the nodes whereas an off-diagonal element expresses how much GIC at one earthing point affects the voltage at another node. In GIC calculations, except for some special treatments of individual sites, the off-diagonal elements are usually neglected by saying simply that the earthing points (are assumed to) lie distantly enough. In this paper, we examine the effects of off-diagonal elements of the earthing impedance matrix, i.e. the effects of interactions between different stations, on GIC calculations in greater detail and more quantitatively than before. We consider a fictitious system that represents a high-voltage power grid and a simple “network” consisting of two stations with a line connecting them. For both systems, the conclusion can be drawn that the off-diagonal elements do not play a major role in practice. Modelling them only approximately, or even ignoring them, is not of great significance compared to other shortcomings involved in GIC calculations. This is particularly true when looking at a power grid as a whole although at some individual stations the neglect may lead to larger errors in GIC values.
A detector telescope’s pitch angle sampling of magnetospheric particles
Authors: Adel Miah M. 
Published: August 2014

Abstract
A geometrical method developed for a particle detector can be extended for application to the determination of the pitch angle sampling capability of the particle telescope of any orientation and for the parent satellite of any orbital orientation. A unit vector tangent to a dipole geomagnetic field line has been calculated from the dipole magnetic field equations in the geomagnetic coordinate system. Rotation matrices have been used, step-by-step, to align the geomagnetic coordinate frame with the detector coordinate frame. The detector selected in this work has its axis tilted with the local zenith direction. The component of the unit vector in the detector coordinate system is found at an observation point characterized by longitude, latitude, and the geocentric radial distance. Pitch angles are measured with respect to the guiding field direction. The pitch angle sampling factor is used in the calculation of detector response functions to particles of different pitch angles. The sampling efficiency functions are useful to make an absolute comparison of magnetospheric particle fluxes measured by particle telescopes under different solar conditions pertaining to different epochs.
A simple model for mantle-driven flow at the top of Earth’s core
Authors: Amit Hagay , Aubert Julien , Hulot Gauthier , Olson Peter 
Published: August 2014

Abstract
We derive a model for the steady fluid flow at the top of Earth’s core driven by thermal coupling with the heterogeneous lower mantle. The model uses a thermal wind balance for the core flow, and assumes a proportionality between the horizontal density gradients at the top of the core and horizontal gradients in seismic shear velocity in the lowermost mantle. It also assumes a proportionality between the core fluid velocity and its radial shear. This last assumption is validated by comparison with numerical models of mantle-driven core flow, including self-sustaining dynamo (supercritical) models and non-magnetic convection (subcritical) models. The numerical dynamo models show that thermal winds with correlated velocity and radial shear dominate the boundary-driven large-scale flow at the top of the core. We then compare the thermal wind flow predicted by mantle heterogeneity with the 150 year time-average flow obtained from inverting the historical geomagnetic secular variation, focusing on the non-zonal components of the flows because of their sensitivity to the boundary heterogeneity. Comparing magnitudes provides an estimate of the ratio of lower mantle seismic anomalies to core density anomalies. Comparing patterns shows that the thermal wind model and the time-average geomagnetic flow have comparable length scales and exhibit some important similarities, including an anticlockwise vortex below the southern Indian and Atlantic Oceans, and another anticlockwise vortex below Asia, suggesting these parts of the non-zonal core flow could be thermally controlled by the mantle. In other regions, however, the two flows do not match well, and some possible reasons for the dissimilarity between the predicted and observed core flow are identified. We propose that better agreement could be obtained using core flows derived from geomagnetic secular variation over longer time periods.
Depth estimation of fumarolic gas source deduced by fume pressure measurement
Authors: Mori Takehiko , Suzuki Takashi , Hirabayashi Jun’ichi , Nogami Kenji , Ohwada Michiko , Yoshikawa Shin 
Published: August 2014

Abstract
The origin of fumarolic gas is hydrothermal boiling in the active fumarolic area and magma degassing in the active volcano where high temperature gas is discharged. The determination of the fumarolic gas source is important for understanding the geothermal activity or the eruption process. However, it is difficult to determine the gas source by geophysical prospecting using seismic or geomagnetic techniques due to the resolution limitation of these techniques. New measurement tools are therefore necessary. The aim of this study was to determine the conduit length—i.e., the depth of the fumarolic gas source—by measuring the fume pressure, which in turn facilitates the determination of the pressure oscillation of a conduit generated by acoustic resonance. We initially assembled the measuring device and measured the fume pressure at an active fumarole in Kusatsu-Shirane volcano, Japan. Our measuring device succeeded in measuring the pressure oscillation generated by acoustic resonance, revealing that the fumarolic gas source at Kusatsu-Shirane volcano has a depth of approximately 40 m. We propose that the use of an acoustic resonance is an effective approach for deducing the fumarolic gas source.