bluuebunny/crossref_metadata_2025_split huggingface dataset:
First Sub-parsec-scale Mapping of Magnetic Fields in the Vicinity of a Very-low-luminosity Object, L1521F-IRS
Authors: Soam Archana , Lee Chang Won , Andersson B-G , Maheswar G. , Juvela Mika , Liu Tie , Kim Gwanjeong , Rao Ramprasad , Chung Eun Jung , Kwon Woojin , Ekta S. 
Published: September 2019

Abstract
L1521F is found to be forming multiple cores and it is cited as an example of the densest core with an embedded VeLLO in a highly dynamical environment. We present the core-scale magnetic fields (B-fields) in the near vicinity of the VeLLO L1521F-IRS using submillimeter polarization measurements at 850 μm using JCMT POL-2. This is the first attempt to use high-sensitivity observations to map the sub-parsec-scale B-fields in a core with a VeLLO. The B-fields are ordered and very well connected to the parsec-scale field geometry seen in our earlier optical polarization observations and the large-scale structure seen in Planck dust polarization. The core-scale B-field strength estimated using the Davis–Chandrasekhar–Fermi relation is 330 ± 100 μG, which is more than 10 times the value we obtained in the envelope (the envelope in this paper is the “core envelope”). This indicates that B-fields are getting stronger on smaller scales. The magnetic energies are found to be 1 to 2 orders of magnitude higher than nonthermal kinetic energies in the envelope and core. This suggests that magnetic fields are more important than turbulence in the energy budget of L1521F. The mass-to-flux ratio of 2.3 ± 0.7 suggests that the core is magnetically supercritical. The degree of polarization is steadily decreasing toward the denser part of the core with a power-law slope of −0.86.
Atmospheric Circulation of Brown Dwarfs and Jupiter- and Saturn-like Planets: Zonal Jets, Long-term Variability, and QBO-type Oscillations
Authors: Showman Adam P. , Tan Xianyu , Zhang Xi 
Published: September 2019

Abstract
Brown dwarfs and directly imaged giant planets exhibit significant evidence for active atmospheric circulation, which induces a large-scale patchiness in the cloud structure that evolves significantly over time, as evidenced by infrared light curves and Doppler maps. These observations raise critical questions about the fundamental nature of the circulation, its time variability, and its overall relationship to the circulation on Jupiter and Saturn. Jupiter and Saturn themselves exhibit numerous robust zonal (east–west) jet streams at the cloud level; moreover, both planets exhibit long-term stratospheric oscillations involving perturbations of zonal wind and temperature that propagate downward over time on timescales of ∼4 yr (Jupiter) and ∼15 yr (Saturn). These oscillations, dubbed the quasi-quadrennial oscillation (QQO) for Jupiter and the semiannual oscillation (SAO) on Saturn, are thought to be analogous to the quasi-biennial oscillation (QBO) on Earth, which is driven by upward propagation of equatorial waves from the troposphere. To investigate these issues, we here present global, three-dimensional, high-resolution numerical simulations of the flow in the stratified atmosphere—overlying the convective interior—of brown dwarfs and Jupiter-like planets. The effect of interior convection is parameterized by inducing small-scale, randomly varying perturbations in the radiative–convective boundary at the base of the model. Radiative damping is represented using an idealized Newtonian cooling scheme. In the simulations, the convective perturbations generate atmospheric waves and turbulence that interact with the rotation to produce numerous zonal jets. Moreover, the equatorial stratosphere exhibits stacked eastward and westward jets that migrate downward over time, exactly as occurs in the terrestrial QBO, Jovian QQO, and Saturnian SAO. This is the first demonstration of a QBO-like phenomenon in 3D numerical simulations of a giant planet.
Measuring the Distances to Quasars at High Redshifts with Strong Lensing
Authors: Liao Kai 
Published: September 2019

Abstract
Strongly lensed quasars with time-delay measurements are well known to provide the “time-delay distances”

, and the angular diameter distances to the lens galaxies D

L
. These two kinds of distances give stringent constraints on cosmological parameters. In this work, we explore a different use of time-delay observables: under the assumption of a flat universe, strong lensing observations can accurately measure the angular diameter distances to the sources D

S
. The corresponding redshifts of the quasars may be up to z

S
∼ 4 according to the forecast. The high-redshift distances would sample the Hubble diagram between SNe Ia and the cosmic microwave background, model-independently providing direct information on the evolution of the nature of our universe, for example, the dark energy equation of state parameter w(z). We apply our method to the existing lensing system SDSS 1206+4332 and get

at z

S
= 1.789. We also make a forecast for the era of Large Synoptic Survey Telescope. The uncertainty of D

S
depends on the redshifts of the lens and the source, the uncertainties of D
Δt
and D

L
, and the correlation between D
Δt
and D

L
. Larger correlation would result in tighter D

S
determination.
Le couple aptus-praestantia dans l’ Éthique de Spinoza
Authors: Legeay Vincent 
Published: September 2019

L’article entend montrer que la notion d’ aptus et la notion de praestantia , au scolie de la proposition 13 de la seconde partie de l’ Éthique , constituent un couple remarquable non anodin, parce qu’en partie repris à Hobbes. Après avoir analysé la teneur de cette reprise, depuis l’œuvre du philosophe anglais, dans le vocabulaire spinoziste, nous avançons que l’aptitude ne peut pas être comprise comme une valeur rapprochée de la puissance optimale, telle qu’elle a parfois été interprétée mais plutôt comme une position gnoséologique favorable vis-à-vis des causes extérieures contrariantes que sont les circonstances, et que l’on pourrait assimiler à une forme de complexité au sens contemporain.
Présentation
Authors: de Negroni Barbara 
Published: September 2019

Le texte de Pierre Francastel que nous publions ici est une communication faite durant un colloque consacré à Nicolas Poussin, qui eut lieu à Paris du 19 au 21 septembre 1958. L’ensemble des communications a été publié, sous la direction d’André Chastel, aux Éditions du CNRS, Paris, 1960. Dans ce texte, Francastel propose une lecture de l'évolution de l'œuvre de Poussin et montre la profonde inventivité de sa peinture.
Visualization of buried anti‐tank landmines and soil pollution: analyses using ground penetrating radar method with attributes and petrographical methods
Authors: Kadioğlu Selma , Kadioğlu Yusuf Kagan 
Published: September 2019

ABSTRACTThis paper presents an approximation to display buried anti‐tank landmines with ground‐penetrating radar method, including physical data attributes by measuring data in a special military field and determination of soil pollution using mineralogical and chemical features of the soil obtained by confocal Raman spectrometry and polarized energy dispersive X‐ray fluorescence, which are petro‐graphical methods, before and after bursting the mine. Two‐dimensional ground penetrating radar data were acquired on parallel profiles using 800‐MHz shielded antenna on unexploded anti‐tank landmines buried approximately 10 cm–15 cm in depth. After general processing in the time domain, we employed migration, a frequency‐wavenumber (F‐K) filter, and ground‐penetrating radar data attributes with an amplitude envelope, spectral whitening, and first‐time derivative to activate anti‐tank landmine visualization. Finally, we obtained three‐dimensional half bird ‘s eye view of the processed volume with each separate attribute. We also derived the transparent three dimensional volumes by assigning opacity to the amplitude‐colour range. The results showed that the depth slices including attributes and the transparent three‐dimensional depth‐volumes could clearly image the anti‐tank landmine. In addition, migration and F‐K filter during special processing were very important in removing data noise. Ground‐penetrating radar data atthbutes—particularly amplitude enveloping— could suppress small phase shifts in the neighbouhng traces of the landmine amplitude anomalies and helped to obtain more complete results showing location and depth in the three‐dimensional volume.The results of the analyses of the major oxide elements and heavy metal elements, such as Fe2O3 Pb, Zn, As, Mn, Mo, Co, Ni, Sb, and Sn, in the test area revealed that there were almost no major differences before and after blasting the anti‐tank landmines. This indicates that one‐time bursting of the anti‐tank landmines in the field has not polluted the soil in this area.
Physical characterisation of soils recovered from the ANZAC battlefield
Authors: Orangi Amir , Narsilio Guillermo A. 
Published: September 2019

ABSTRACTAs part of a unique tri‐nation study to commemorate the centenary of the iconic First World War ANZAC battlefield, this paper summarises the results of a laboratory experimental investigation of some geotechnical and geophysical characteristics of soil recovered from this field in Gallipoli, Turkey. The geophysical characterisation of these samples comprises the determination of the dielectric properties, namely real, imaginary and dielectric dispersion, over a frequency band between 200 MHz and 6 GHz. This characterisation is performed at the samples’ in situ state as well as in a controlled range of water content from oven‐dried to saturation. Specific frequencies pertaining to certain in situ geophysical applications and satellite surveys have been targeted as reference frequencies to study the dielectric data. Moreover, attenuation coefficients related to ground‐penetrating radar applications are also estimated at 200 MHz for a range of water contents. Microstructure and mineralogy were examined by environmental scanning electron microscopy and X‐ray diffraction techniques, respectively. Given the historical and archaeological significance of the ANZAC battlefield, these results can be used for future feasibility studies, planning, and result interpretation of geophysical investigations, including choosing the most appropriate time of the year and geophysical prospection tools, in this restricted‐access study area.
The 3D Autojuggie: automating acquisition of 3D near‐surface seismic reflection data
Authors: Miller Brian E. , Sloan Steven D. , Tsoflias Georgios P. , Steeples Don W. 
Published: September 2019

ABSTRACTNew instrumentation, known as the 3D Autojuggie, has been developed that allows acquisition of three‐dimensional shallow seismic reflection data in a cost‐effective manner. The 3D Autojuggie is capable of simultaneously planting 220 geophones with 0.5‐m spacing in the inline and crossline directions in less than 1 minute. Likewise, all 220 geophones can be picked up in the same amount of time so that the receiver grid can be moved and redeployed on the order of a few minutes without disconnecting cables and seismographs. This significantly reduces the time required to roll geo‐phones and cables and the number of crew members needed for three‐dimensional high‐resolution seismic surveying. While efficiency of three‐dimensional surveying is demonstrated here, the use of the Autojuggie will be limited in rough terrain and in dry or rocky top soil.This study presents two field tests of the 3D Autojuggie. The first one was conducted over soil using conventional geophones with spikes, and the second one was conducted over hard pavement using geophones mounted on base plates. Each dataset is compared to corresponding walkaway lines of conventional manually placed control geophones. Data acquired using the 3D Autojuggie are directly comparable and nearly indistinguishable to hand‐planted geophones. Field experiments resulted in a minimum of triple the acquisition efficiency increase compared with conventional geophone deployment methods. This work demonstrates that the 3D Autojuggie can facilitate the acquisition of high‐resolution three‐dimensional seismic data, making possible routine ultra‐shallow seismic imaging.
Using ground‐penetrating radar to explore the cemented soil horizon in an arid region in Iran
Authors: Abbaszadeh Afshar Farideh , Ayoubi Shamsollah , Castrignanò Annamaria , Quarto Ruggiero , Mahmoudzadeh Ardekani Mohammad Reza 
Published: September 2019

ABSTRACTPetrosalic horizon (cemented by soluble salts) is identified as a root‐restricting layer in the arid and semi‐arid regions. The knowledge of the variability of cemented layers within the soil profiles provides valuable information to decision‐makers for agricultural and/or engineering activities. This study was conducted to evaluate the potential of ground‐penetrating radar in detecting petrosalic horizon within the soil pedon in an arid area (Kerman Province, southeastern Iran). The measurements were performed using an impulse ground‐penetrating radar system with a centre frequency of 250 MHz along ten parallel transects of 100‐m length and 10‐m distance between two consecutive transects at two sites. The results of the soil stratigraphy indicated the presence of petrosalic horizons at 12‐ to 36‐cm depth. The ground‐penetrating radar images showed patterns corresponding to these soil horizons. The interpreted radargrams were quite consistent with the findings of the soil pedons. It is, therefore, suggested that ground‐penetrating radar could be employed to detect the boundaries between different soil horizons in the arid areas with various degrees of conductivity. This, in turn, helps differentiate soil‐mapping units and improve the reliability and accuracy of digital soil maps. The results confirmed that ground‐penetrating radar could be used as a rapid, efficient and non‐destructive tool providing highresolution and continuous visualisation of the soil horizons to detect the presence and depth of petro‐salic horizons. Such information could be crucial in making decisions in agricultural practices (e.g., creating gardens) and engineering activities (e.g., constructing roads and buildings).
Probe rotation effects on direction of arrival estimation in array‐type directional borehole radar
Authors: Ebihara Satoshi , Wada Kazushige , Karasawa Shinsuke , Kawata Kentaro 
Published: September 2019

ABSTRACTThis paper discusses the relationship between feeding line delay compensation and direction of arrival estimation in an array‐type directional borehole radar. In this radar, since the space available for an array antenna is limited by the borehole diameter, direction of arrival estimation is based on small travel time differences among array elements, and an accurate compensation of feeding line delays is important. Computer simulation confirmed that the radar probe rotation in a borehole leads to errors in the direction of arrival estimation of greater than 15° if the delays associated with the feeding array antenna elements are not compensated to within 0.1 ns. This may be caused by a failure to measure the time delays of electrical circuits around the feeding points of the antenna elements. In this case, we suggest that the lengths of system components other than the coaxial cables should be kept to less than 3 cm. Based on these investigations, we developed an array‐type directional borehole radar for a geotechnical project to locate foundation piles. In a field experiment, we confirmed that direction of arrival estimation errors were below about 15°, although the radar probe rotated through more than 180° during the measurement, thanks to correct compensation of the cables. With the correct compensation, we demonstrated three‐dimensional location of a buried cylindrical conducting object, which was located at 2 m from the radar in wet soil. We were able to estimate the reflection point position with an accuracy of 34 cm, which is the averaged error of the three‐dimensional location, while allowing the radar probe to rotate.
A shear‐wave seismic system using full‐waveform inversion to look ahead of a tunnel‐boring machine
Authors: Bharadwaj Pawan , Drijkoningen Guy , Mulder Wim , Thorbecke Jan , Neducza Boriszlav , Jenneskens Rob 
Published: September 2019

ABSTRACTIn the near surface with unconsolidated soils, shear‐wave properties can often be characterised better and with a higher resolution than compressional‐wave properties. To enable imaging ahead of a tunnel‐boring machine, we developed a seismic prediction system with a few shear‐wave vibrators and horizontal receivers. The boring process is interrupted at regular intervals to carry out active surveys. The vibrators are then pushed against the rock or soil in front of the cutting wheel of the machine. The design of the vibrators is based on linear synchronous motor technology that can generate very low frequencies, starting at 5 Hz. These vibrators generate a force in a direction perpendicular to the tunnel axis. Horizontal receivers measure the particle velocity, mainly due to the horizontally polarised shear waves. Because imaging with conventional migration methods suffers from artefacts, caused by the incomplete aperture and inaccuracies in the assumed velocity model, we use two‐dimensional horizontally polarised shear full‐waveform inversion to resolve the subsurface shear properties. The classic cycle‐skipping problem, which can make the application of full‐waveform inversion cumbersome, is avoided by the capacity of the vibrators to generate low frequencies. In this paper, we demonstrate the capabilities of the proposed seismic system through a number of synthetic and field experiments.
Forward and inverse modelling of electrical properties of some sandstone rocks using renormalisation group method
Authors: Gomaa Mohamed M. , Kassab Mohamed A. 
Published: September 2019

ABSTRACTElectrical properties of some sandstone rocks (conductivity and dielectric constant) were investigated as a function of frequency (100 Hz to 100 kHz). Such heterogeneous specimens contain semiconducting constituents (silt and clay) and insulating constituents (sand, air, and carbonates). A theoretical pseudo‐random renormalisation group method was used to predict the electrical properties of such random mixture. Four phases were used in the model to consider the detailed texture of the constituent materials. The measured electrical properties (conductivity and dielectric constant) versus frequency of these samples were analysed to predict the texture or connections of these four phases. From the analysis, these four phases were suggested to be (1) carbonates, (2) sand coated with clay and coated with air, (3) carbonates coated with clay and coated with air, and (4) pure sand. The forward problem predicts the electrical properties versus frequency using the pseudo‐random renormalisation group method for certain concentrations of the constituent materials distributed among the random four phases. The forward model is used to fit the measured response to obtain the expected concentrations of rock constituents in the proposed four phases using a parameter search method (inverse problem). The obtained accordance between the experimental and modelled characteristics in much of the frequency band used suggests that the pseudo‐random renormalisation group method with the supposed four phases reasonably represents the main mineralogical composition of the rock.
Direct monitoring of active geohazards: emerging geophysical tools for deep‐water assessments
Authors: Clare Michael A. , Vardy Mark E. , Cartigny Matthieu J.B. , Talling Peter J. , Himsworth Matthew D. , Dix Justin K. , Harris John M. , Whitehouse Richard J.S. , Belal Mohammad 
Published: September 2019

ABSTRACTSeafloor networks of cables, pipelines, and other infrastructure underpin our daily lives, providing communication links, information, and energy supplies. Despite their global importance, these networks are vulnerable to damage by a number of natural seafloor hazards, including landslides, turbidity currents, fluid flow, and scour. Conventional geophysical techniques, such as high‐resolution reflection seismic and side‐scan sonar, are commonly employed in geohazard assessments. These conventional tools provide essential information for route planning and design; however, such surveys provide only indirect evidence of past processes and do not observe or measure the geohazard itself. As such, many numerical‐based impact models lack field‐scale calibration, and much uncertainty exists about the triggers, nature, and frequency of deep‐water geohazards. Recent advances in technology now enable a step change in their understanding through direct monitoring. We outline some emerging monitoring tools and how they can quantify key parameters for deep‐water geohazard assessment. Repeat seafloor surveys in dynamic areas show that solely relying on evidence from past deposits can lead to an under‐representation of the geohazard events. Acoustic Doppler current profiling provides new insights into the structure of turbidity currents, whereas instrumented mobile sensors record the nature of movement at the base of those flows for the first time. Existing and bespoke cabled networks enable high bandwidth, low power, and distributed measurements of parameters such as strain across large areas of seafloor. These techniques provide valuable new measurements that will improve geohazard assessments and should be deployed in a complementary manner alongside conventional geophysical tools.
Measurement of geophysical parameters on clay samples at the solid–fluid transition
Authors: Carrière Simon R. , Bièvre Gregory , Jongmans Denis , Chambon Guillaume , Bellot Hervé , Lebourg Thomas 
Published: September 2019

ABSTRACTFluidisation occurring in clay‐rich landslides poses serious threats to populations and infrastructures and has been the subject of numerous studies to apprehend its rheological origin. In parallel, noninvasive geophysical techniques for monitoring landslides have shown considerable developments as a means to obtain thein‐situgeotechnical parameters. This study investigates the influence of fluidisation on two geophysical parameters: the shear wave velocity,, and the electrical resistivity,. Both parameters are widely used in landslide monitoring as they are sensitive, respectively, to soil stiffness and water content, two key parameters for material fluidisation. Laboratory tests were carried out on soil samples collected in five flow‐like landslides occurring in very different geological conditions. A plate–plate rheometer was used to provoke fluidisation, andwas measured during oscillatory tests. The rheometer was redesigned for resistivity measurements, incorporating circular electrodes in polyvinyl chloride plates. Results show that (i) all soils exhibit a dramatic drop inat the fluidisation, and (ii) the resistivity does not significantly vary at the solid–fluid transition. These last results are analysed in terms of clay particles arrangement using the laws of Archie and Waxman–Smits, and the impact on geophysical monitoring of a landslide is discussed.