bluuebunny/crossref_metadata_2025_split huggingface dataset:
Derived Characteristics of the Ross Ice Shelf, Antarctica (Abstract only)
Authors: Thomas R.H. , Macayeal D.R. 
Published: September 2017

Results of the Ross Ice Shelf Geophysical and Glaciologlcal Survey (RIGGS) provide the most complete data set available for any large portion of the polar ice sheets. In this paper, we use RIGGS data to calculate some ice-shelf characteristics. These include steady-state particle trajectories through the ice shelf and the depth of isochronous surfaces, which are of particular importance in choosing a drilling site where ice from the grounded West Antarctic ice sheet is likely to be near the surface. Our estimates for depth to ice originating from the 500 m elevation contour show good agreement with depths to a glaciochemical transition in four ice cores that is believed to be associated with this elevation. This suggests that, for much of the ice shelf, there have been no dramatic and sustained departures from steady state during the past 1.5 to 2.5 ka. With the RIGGS data and an assumed bottom melting rate distribution we calculate steady-state temperature profiles at each of the measurement stations. Then, adopting an ice-flow law deduced from laboratory experiments and ice-shelf measurements, we obtain an effective flow-law parameter for each of these sites. Using these values, the measured strain rate field is transformed to an equivalent stress field over the ice shelf. The stresses are determined by the ice-shelf freeboard and by the force field exerted on the ice shelf by its sides and by ice rises, and our analysis yields estimates of these restraining forces F for the Ross Ice Shelf. An apparent increase in F very close to the ice front suggests that the ice shelf possesses a narrow seaward fringe of anomalously stiff ice. We suspect that this represents the effects of increased bottom-melting rates (and therefore colder and stiffer ice) very close to the ice front.In order to illustrate the role of the restraining forces in controlling ice-shelf behavior, we calculate the strain-rate field for an unrestricted Ross Ice Shelf, i.e. one that is detached from its sides and contains no ice rises. Currently the creepthinning rate for most of the ice shelf is 0.5 to 1m a−1 for an unrestricted ice shelf, but it would increase to 1 to 10 m a −1, with values up to 60 ma− 1 up-stream of the ice risesThis paper has been accepted for publication in the Journal of Glaciology.
Mechanical Tests of Fresh Ice Core (Abstract only)
Authors: Shoji H. , Langway C.C. 
Published: September 2017

Uniaxial compression tests (UCT) under constant cross-head speed and simple shear tests (SST) under constant load have been carried out in a snow cave at -16°C on ice cores within at most one month of extraction from depths of 235, 504, 708, and 896 m at Dye-3, Greenland, as part of the Greenland Ice Sheet Program (GISP), in order to improve understanding of flow behavior. UCT specimens had their stress axis at 45° from the core axis and SST specimens had their shear parallel to the horizontal plane of the core, so that in both cases maximum resolved shear stress was in the horizontal plane of the ice sheet.Fracture stresses in UCT had characteristic values for each depth corresponding to core quality. When effective strain-rate was plotted against effective shear stress on a double logarithmic plot, (1) data from the same depth fell on the same straight line for both tests, (2) for a given stress, strainrate varied with core-depth by less than half an order of magnitude, and (3) the stress exponent lay between 2 and 2.5, significantly less than the 3 to 4 reported for polycrystalline ice.Values extrapolated from the present data agree quite well with those deduced from bore-hole tilting measurements at Byrd station, Antarctica, and Camp Century, Greenland.
Subglacial Processes at Bondhusbreen, Norway: Preliminary Results
Authors: Hagen Jon Ove , Wold Bjørn , Liestøl Olav , Østrem Gunnar , Sollid Johan Ludvig 
Published: September 2017

Subglacial hydrology, sediment transport, pressure, and temperature have been studied beneath approximately 160 m of ice at Sondhusbreen, an outlet glacier from Folgefonni in south-western Norway.The volume of the mean annual water discharge passing through the study area is about 60x106 m3. Most of this water is diverted into a tunnel system in the rock beneath the glacier and used for hydroelectric power generation. At the beginning of the melt season, this water flows in multiple small channels, but later it collects in one or two main channels. The discharge of eroded material is about 7 600 tonnes a−1. Of this, roughly 90% is transported by running water.Pressure gauges and thermistors were installed at two sites under the glacier. Results from one of the sites indicated that ice can stagnate in some leeward positions, as almost no ice movement was recorded during most of the period of measurement and the pressure distribution was nearly hydrostatic. However, increased water pressure during the summer apparently resulted in the opening of subglacial cavities, adding a local up-glacier component to the flow at this site.At another location, about 20 m up-glacier, non-hydrostatic differential pressures of up to 30 bar were recorded across an artificial dome-shaped obstacle. The flow at this location was more steady, in general, but rather dramatic effects were recorded when a boulder 0.3 m3 in size passed over the obstacle, destroying one of the pressure sensors. This sensor recorded a pressure of 90 bar before failing. The boulder was moving at a speed of about 40 mm d-1, whereas the sliding velocity of the ice was 80 mm d-1. Temperature measurements suggest that the difference in temperature across this obstacle was less than 0.03 deg, or an order of magnitude less than expected. This may mean that water was squeezed out of the ice on the stoss side of the obstacle as suggested by Robin (1976), and thus was not available to warm the lee-side ice by refreezing.
A Surface Integral Method for Determining Ice Loads on Offshore Structures from In Situ Measurements
Authors: Johnson Jerome B. 
Published: September 2017

Two methods are presented for calculating ice loads on structures using measurements from sensors imbedded in a floating ice sheet and from instruments attached to a structure. The first method uses a mathematical model describing ice/structure interaction for a cylindrical structure to interpret stress measurements. This technique requires only a few sensors to develop an estimate of ice loads, However, analytical and experimental results indicate that using a mathematical model to interpret stress measurements can result in inaccurate load estimates due to uncertainty in the accuracy of the model and and the uncertainty of using local ice stresses to calculate total ice forces. The second method of calculating ice loads on structures utilizes Euler and Cauchy’s stress principle. In this, the surface integral method, the force acting on a structure is determined by summing the stress vectors acting on a surface which encompasses the structure. Application of this technique requires that the shear and normal components of stress be known along the surface. Sensors must be spaced close enough together so that local stress variations due to the process of ice failure around a structure can be detected. The surface integral method is a useful technique for interpreting load and stress measurements since a knowledge of the mechanism of ice/structure interactions is not needed. The accuracy of the method is determined by the density of sensors along the surface. A disadvantage of the technique is that a relatively large number of sensors are needed to determine the stress tensor along the surface of interest.The surface integral method can be used to examine the effects of grounded ice rubble on structural ice loads. Two instrumented surfaces, one enclosing a structure and the other enclosing the structure and rubble field can be used to estimate the load acting only on the structure and also on the structure/ rubble-field system.
Automatic Collection of Tilt and Strain Data from Tabular Icebergs
Authors: Kristensen Monica , Squire Vernon A. 
Published: September 2017

Drift tracks of Antarctic tabular icebergs have been studied by means of satellite-tracked buoys since the early 1970s. More recently, a growing interest in the possibility of using Antarctic icebergs to supply fresh water to arid areas has made resources available for more sophisticated experiments, and in 1978 three prototype stations were designed to measure interactions between tabular icebergs and the ocean. These stations were deployed in late 1979, and in early 1981.The purpose of this paper is, firstly, to communicate some of our experiences with an earlier type of automatic data collection platform, and, secondly, to show that the substantial amount of tilt and strain data available from this station is unsuitable for data analysis. We discuss aspects of the data collected by the first of the three automatic stations, paying particular attention to the quality of the recorded strain and tilt data. It is shown that an unfortunate choice of instrument sensitivity and range severely limits the usefulness of the collected data, and that limitations in the data sampling regime make data analysis by conventional statistical methods very difficult. Several changes are proposed for the design of future data collection platforms for tabular icebergs, and some suggestions are made about data sampling. As this paper only concerns iceberg research, we do not discuss investigations of sea-ice drift made in the same area.
NITROXYNIL UNCOUPLES OXIDATIVE PHOSPHORYLATION IN THE CELL MITOCHONDRIA AND A DRUG WHEREVER INJECTABLES ARE PREFERRED OVER DRENCHES
Authors: Rahman M. M. , Kabir A. , Ahmed S. , Islam M. K. , Rahman M. S. , Alam A. , Mubeen M. A. A. , Yasmin M. S. , Hossain M. S. , Haque M. W. U , Mia M. T. 
Published: September 2017

In the absence of effective vaccines and because of practical limitations in management options to control the snail intermediate hosts, the control of liver fluke infection and disease in livestock relies heavily on the use of flukicidal anthelmintics. Nitroxynil is a nitrate derivative from benzene compounds and presents a flukicide effect and is commonly used as the one with best spectrum from all the nitrate derivative trematocides. The drug is in fact, a low spectrum anthelmintic effective against fascioliasis, an important parasitic disease caused by flukes like Fasciola hepatica, Fasciola gigantica, affecting significantly the ruminant production by means of reducing the growth, conversion rate, milk production, quality and quantity of meat and reproduction. Nitroxynil also does hold efficacy against few roundworms mainly blood-sucking species as well as certain myiasis. It is not effective against most of the tape worms or external parasites. It is chemically constitute of yellow benzene crystals, slightly soluble in water and soluble in organic solvents, almost odorless and is characterized for being a stable solution, but it precipitates in presence of calcium and other salts. It is marketed as bright orange-red injectable solution due that by this route is six times more efficient than by oral route. Nitroxynil is a safe drug and it can be used at any stage of pregnancy. It does not affect fertility, gestation or fetus formation and in no way impede the reproductive performance of stallions. Its presented as two salts, nitroxynil megaglumine and nitroxynil eglumine. The nitroxynil in salt is hydrosoluble having neutral pH and is exclusively administered to animals by subcutaneous route. The flukicide resistance phenomenon is already present in many countries in the same way that resistance against other anthelmintic drugs is spreading around worldwide. Because of the absence of new drugs against fluke infections, it is necessary to prove and compare the efficacy of the anthelmintics to prevent resistance development. In view of that we endeavored elucidating the latest progress of one such widely used flukicide nitroxynil.
Quasar Rain: The Broad Emission Line Region as Condensations in the Warm Accretion Disk Wind
Authors: Elvis Martin 
Published: September 2017

Abstract
The origin of the broad emission line region (BELR) in quasars and active galactic nuclei is still unclear. I propose that condensations form in the warm, radiation-pressure-driven, accretion disk wind of quasars creating the BEL clouds and uniting them with the other two manifestations of cool (∼104 K) gas in quasars, the low ionization phase of the warm absorbers (WAs) and the clouds causing X-ray eclipses. The cool clouds will condense quickly (days to years), before the WA outflows reach escape velocity (which takes months to centuries). Cool clouds form in equilibrium with the warm phase of the wind because the rapidly varying X-ray quasar continuum changes the force multiplier, causing pressure waves to move gas into stable locations in pressure–temperature space. The narrow range of two-phase equilibrium densities may explain the (luminosity)

scaling of the BELR size, while the scaling of cloud formation timescales could produce the Baldwin effect. These dense clouds have force multipliers of order unity and so cannot be accelerated to escape velocity. They fall back on a dynamical timescale (months to centuries), producing an inflow that rains down toward the central black hole. As they soon move at Mach ∼10–100 with respect to the WA outflow, these “raindrops” will be rapidly destroyed within months. This rain of clouds may produce the elliptical BELR orbits implied by velocity-resolved reverberation mapping in some objects and can explain the opening angle and destruction timescale of the narrow “cometary” tails of the clouds seen in X-ray eclipse observations. Some consequences and challenges of this “quasar rain” model are presented, along with several avenues for theoretical investigation.
First Detection of a Strong Magnetic Field on a Bursty Brown Dwarf: Puzzle Solved
Authors: Berdyugina S. V. , Harrington D. M. , Kuzmychov O. , Kuhn J. R. , Hallinan G. , Kowalski A. F. , Hawley S. L. 
Published: September 2017

Abstract
We report the first direct detection of a strong, 5 kG magnetic field on the surface of an active brown dwarf. LSR J1835+3259 is an M8.5 dwarf exhibiting transient radio and optical emission bursts modulated by fast rotation. We have detected the surface magnetic field as circularly polarized signatures in the 819 nm sodium lines when an active emission region faced the Earth. Modeling Stokes profiles of these lines reveals the effective temperature of 2800 K and log gravity acceleration of 4.5. These parameters place LSR J1835+3259 on evolutionary tracks as a young brown dwarf with the mass of

and age of 22 ± 4 Myr. Its magnetic field is at least 5.1 kG and covers at least 11% of the visible hemisphere. The active region topology recovered using line profile inversions comprises hot plasma loops with a vertical stratification of optical and radio emission sources. These loops rotate with the dwarf in and out of view causing periodic emission bursts. The magnetic field is detected at the base of the loops. This is the first time that we can quantitatively associate brown dwarf non-thermal bursts with a strong, 5 kG surface magnetic field and solve the puzzle of their driving mechanism. This is also the coolest known dwarf with such a strong surface magnetic field. The young age of LSR J1835+3259 implies that it may still maintain a disk, which may facilitate bursts via magnetospheric accretion, like in higher-mass T Tau-type stars. Our results pave a path toward magnetic studies of brown dwarfs and hot Jupiters.
On the Nature of Off-limb Flare Continuum Sources Detected by SDO/HMI
Authors: Heinzel P. , Kleint L. , Kašparová J. , Krucker S. 
Published: September 2017

Abstract
The Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory has provided unique observations of off-limb flare emission. White-light continuum enhancements were detected in the “continuum” channel of the Fe 6173 Å line during the impulsive phase of the observed flares. In this paper we aim to determine which radiation mechanism is responsible for such enhancement being seen above the limb, at chromospheric heights around or below 1000 km. Using a simple analytical approach, we compare two candidate mechanisms, the hydrogen recombination continuum (Paschen) and the Thomson continuum due to scattering of disk radiation on flare electrons. Both mechanisms depend on the electron density, which is typically enhanced during the impulsive phase of a flare as the result of collisional ionization (both thermal and also non-thermal due to electron beams). We conclude that for electron densities higher than 1012 cm−3, the Paschen recombination continuum significantly dominates the Thomson scattering continuum and there is some contribution from the hydrogen free–free emission. This is further supported by detailed radiation-hydrodynamical (RHD) simulations of the flare chromosphere heated by the electron beams. We use the RHD code FLARIX to compute the temporal evolution of the flare-heating in a semi-circular loop. The synthesized continuum structure above the limb resembles the off-limb flare structures detected by HMI, namely their height above the limb, as well as the radiation intensity. These results are consistent with recent findings related to hydrogen Balmer continuum enhancements, which were clearly detected in disk flares by the IRIS near-ultraviolet spectrometer.
A Theoretical Model of X-Ray Jets from Young Stellar Objects
Authors: Takasao Shinsuke , Suzuki Takeru K. , Shibata Kazunari 
Published: September 2017

Abstract
There is a subclass of X-ray jets from young stellar objects that are heated very close to the footpoint of the jets, particularly DG Tau jets. Previous models have attributed the strong heating to shocks in the jets. However, the mechanism that localizes the heating at the footpoint remains puzzling. We presented a different model of such X-ray jets, in which the disk atmosphere is magnetically heated. Our disk corona model is based on the so-called nanoflare model for the solar corona. We show that the magnetic heating near the disks can result in the formation of a hot corona with a temperature of ≳106 K, even if the average field strength in the disk is moderately weak, ≳1 G. We determine the density and the temperature at the jet base by considering the energy balance between the heating and cooling. We derive the scaling relations of the mass-loss rate and terminal velocity of jets. Our model is applied to the DG Tau jets. The observed temperature and estimated mass-loss rate are consistent with the prediction of our model in the case of a disk magnetic field strength of ∼20 G and a heating region of <0.1 au. The derived scaling relation of the temperature of X-ray jets could be a useful tool for estimating the magnetic field strength. We also find that the jet X-ray can have a significant impact on the ionization degree near the disk surface and the dead zone size.
3XMM J181923.7–170616: An X-Ray Binary with a 408 s Pulsar
Authors: Qiu Hao , Zhou Ping , Yu Wenfei , Li Xiangdong , Xu Xiaojie 
Published: September 2017

Abstract
We carry out a dedicated study of 3XMM J181923.7–170616 with an approximate pulsation period of 400 s using the XMM-Newton and Swift observations spanning across nine years. We have refined the period of the source to 407.904(7) s (at epoch MJD 57142) and constrained the 1σ upper limit on the period derivative

. The source radiates hard, persistent X-ray emission during the observation epochs, which is best described by an absorbed power-law model (Γ ∼ 0.2–0.8) plus faint Fe lines at 6.4 and 6.7 keV. The X-ray flux revealed a variation within a factor of 2, along with a spectral hardening as the flux increased. The pulse shape is sinusoid-like and the spectral properties of different phases do not present significant variation. The absorption

(

) is similar to the total Galactic hydrogen column density along the direction, indicating that it is a distant source. A search for the counterpart in optical and near-infrared surveys reveals a low-mass K-type giant, while the existence of a Galactic OB supergiant is excluded. A symbiotic X-ray binary (SyXB) is the favored nature of 3XMM J181923.7–170616 and can essentially explain the low luminosity of

, slow pulsation, hard X-ray spectrum, and possible K3 III companion. An alternative explanation of the source is a persistent Be X-ray binary (BeXB) with a companion star no earlier than B3-type.
An Upper Limit on the Milky Way Mass from the Orbit of the Sagittarius Dwarf Satellite
Authors: Dierickx Marion I. P. , Loeb Abraham 
Published: September 2017

Abstract
As one of the most massive Milky Way (MW) satellites, the Sagittarius dwarf galaxy played an important role in shaping the Galactic disk and stellar halo morphologies. The disruption of Sagittarius over several close-in passages has populated the halo of our Galaxy with large-scale tidal streams and offers a unique diagnostic tool for measuring its gravitational potential. Here, we test different progenitor mass models for the MW and Sagittarius by modeling the full infall of the satellite. We constrain the mass of the Galaxy based on the kinematics of the satellite remnant and multiple tidal streams of Sagittarius. Our semianalytic modeling of the orbital dynamics agrees with full N-body simulations, and favors low values for the MW mass,

. This conclusion eases the tension between ΛCDM and the observed parameters of the MW satellites.
3D Magnetohydrodynamic Models of Nonthermal Photon Emission in the Binary System γ2 Velorum
Authors: Reitberger K. , Kissmann R. , Reimer A. , Reimer O. 
Published: September 2017

Abstract
Recent reports claiming an association of the massive star binary system

Velorum (WR 11) with a high-energy γ-ray source observed by Fermi-LAT contrast the so far exclusive role of η Carinae as the hitherto only detected γ-ray emitter in the source class of particle-accelerating colliding-wind binary (CWB) systems. We offer support to this claim of association by providing dedicated model predictions for the nonthermal photon emission spectrum of

Velorum. We use 3D magnetohydrodynamic modeling (MHD) to investigate the structure and conditions of the wind-collision region (WCR) of

Velorum including the important effect of radiative braking in the stellar winds. A transport equation is then solved for the entire computational domain to study the propagation of relativistic electrons and protons. The resulting distributions of particles are subsequently used to compute nonthermal photon emission components. In agreement with observation in X-ray spectroscopy, our simulations yield a large shock-cone opening angle. We find the nonthermal γ-ray emission of

Velorum to be of hadronic origin owing to the strong radiation fields in the binary system, which inhibit the acceleration of electrons to energies sufficiently high for efficient inverse-Compton radiation. We also discuss the strong dependence of a hadronic γ-ray component on the energy-dependent diffusion used in the simulations. Of two mass-loss rates for the WR star found in literature, only the higher rate is able to accommodate the observed γ-ray spectrum with reasonable values for important simulation parameters such as the injection ratio of high-energy particles within the WCR.