bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparisons of Ogive Systems Under Various Regimes
Authors: Atherton David 
Published: September 2017

AbstractIt is suggested that the dark and light bands associated with a wave ogive system are the result of preferential adsorption of wind-blown dust by interstitial water held in narrow coarsely crystalline bands, which are more frequent in the dark bands. These narrow bands are presumed to be produced by regelation on the closure of extensive crevasses in the cwm zone above the ice fall and that, although originally uniformly distributed, there is a bunching effect caused by velocity fluctuations in the glacier at the top of the ice fall. These velocity fluctuations, which are attenuated by irregularities in the glacier’s bed, produce waves at these points, multiple irregularities producing multiple wave systems.
Glaciation of Observation Hill, Hut Point Peninsula, Ross Island, Antarctica
Authors: Forbes Robert B. , Ester Donald W. 
Published: September 2017

AbstractEast-west glacial striations and grooves were discovered on the summit ridge of Observation Hill, which parallel the present direction of shelf ice movement to the east and south-east of the Hut Point peninsula. This evidence suggests that Observation Hill may have been glaciated by a thickened McMurdo lobe of the adjacent Ross Ice Shelf, moving west, as it does today.
Some Photogrammetric and Geodetic Aspects of Measurement of Glacier Surface Movement as Function of Time
Authors: Adler Ron K. H. 
Published: September 2017

AbstractThe ice movement on the Byrd Glacier, Antarctica, was measured as function of time, on the basis of aerial photography. The method of aero-levelling strip triangulation with a minimum of geodetic control was applied. The methods and procedures were verified over Laufen-Bauma test area.
Water Pressure under a Glacier
Authors: Mathews W. H. 
Published: September 2017

AbstractObservations in a deep mine working which reached the base of a valley glacier some 150 m. below the ice surface indicated an initial cold and impervious condition at and near the ice–rock contact. Later, however, an excellent hydraulic connection with free water in the upper layers of the glacier was established, perhaps by the thawing of a passage upward through the ice by warm water escaping from the mine. Subsequent records of water levels, or of water pressures, within the mine, reflecting conditions in the upper part of the glacier, show periods of moderately steady conditions, at times showing slight diurnal fluctuations, interrupted by irregular and catastrophic surges, particularly during periods of rapid snow melt and heavy rains. A seasonal cycle in pressure is suggested by the record.
Non-Basal Slip as a Major Deformation Process in the Creep of Polycrystalline Ice
Authors: Tegart W. J. McG. 
Published: September 2017

AbstractPublished data on the creep of polycrystalline ice and crystals oriented for non-basal slip are discussed in terms of theories of prismatic slip in hexagonal metals. It is concluded that creep of polycrystalline ice near the melting point is controlled by non-basal slip but a decision on the exact mechanism of slip cannot be made on the basis of available data.
Net Balance, Surface Lowering, and Ice-Flow Pattern in the Interior of Lewis Glacier, Mount Kenya, Kenya
Authors: Hastenrath Stefan 
Published: September 2017

AbstractObservations obtained in a long-term monitoring program on Lewis Glacier, Mount Kenya, include measurements of net balance and velocity at a stake network over the period 1978–82, and airborne mapping of the glacier surface topography at the beginning and end of this interval. Horizontal and vertical flow components and mass continuity are evaluated along the longitudinal axis of the glacier.The largest horizontal velocity at the surface is about 5 m a−1, while the submergent vertical velocity at the surface in the upper, and the emergent component in the lower glacier are of the order of 1–2 m a−1. Horizontal and vertical flow components in the interior of the glacier are calculated from the surface observations under plausible assumptions. Isotachs and streamlines plotted in a longitudinal–vertical cross-section permit the estimation of representative residence times of ice within Lewis Glacier. The largest values for the longest trajectories with submergence at the surface in the uppermost area of the glacier and emergence near the snout are of the order of a few centuries. However, such estimates are compromised, in particular, by the continuing non-equilibrium conditions of Lewis Glacier.Mass continuity is directly related to the vertical motion field. In the upper area of the glacier the submergence velocity exceeds the rise of glacier surface observed with respect to the stake network, while in the lower glacier the emergent flow component falls short of the local negative net balance. This differing behavior of altitudinal zones is consistent with the fact that actual lowering of the glacier surface topography documented by the repeated airborne mappings is larger than expected from the stake network in the upper but less in the lower glacier. This differing behavior of altitude zones appears mitigated by the tendency for confluence in the upper and diffluence in the lower glacier.
Elastic Constants of Artificial and Natural Ice Samples by Brillouin Spectroscopy
Authors: Gammon P. H. , Kiefte H. , Clouter M. J. , Denner W. W. 
Published: September 2017

AbstractThe method of Brillouin spectroscopy has been used to measure the dynamic elastic moduli of local homogeneous regions in ice samples representing four different environments of formation. These included artificial ice frozen from distilled water, clear monocrystalline glacial ice, bubbly lake ice, and sea ice. The samples studied were found to have identical local elastic properties. Accordingly the elastic properties of homogeneous monocrystalline ice have been found not to vary with sample age, with impurities present at the time of freezing, or with crystal quality. The bulk elastic properties of ice remain, of course, subject to modification by different crystal grain textures and the presence of inclusions of various sorts. Because the elastic constants obtained in the present work are subject to smaller overall uncertainty than values measured previously, it is believed that they are the most reliable obtained to date. The values at −16 °C were determined to be c11 = 139.29 ± 0.41, c12 = 70.82 ± 0.39, c13 = 57.65 ± 0.23, c33 = 150.10 ± 0.46, c44 = 30.14 ± 0.11 (units of 108 N m− 2 or kbar). A full range of derived elastic parameters for monocrystalline ice and for homogeneous isotropic polycrystalline ice has been calculated.
Annual net balance of North Cascade glaciers, 1984-94
Authors: Pelto Mauri S. 
Published: September 2017

AbstractAnnual net balance eight North Cascade glaciers during the 1984-94 period has been determined by measurement of total mass loss firn and ice melt and ice melt and, residual snow depth at the end of the Summer season. Overall spatial density of measurment points is 200 points km−2. Mean annual balance of North Clascade glaciers from 1984 to 1994 has been −0.38 ma−1. The resulting 4.2 m loss in water-equivalent thickness is significant, since North Cascade glaciers have an average thickness of 30–50 m.Cross-correlation of annual net balance Ior eight glaciers ranges from 0.83 to 0.97. This indicates the mass balances of the eight glaciers have been responding similarly to elimate conditions despite their range of topographic and geographic characteristics. Annual net balance of individual glaciers was correlated with climate records. The highest ablation-season correlation coefficient is mean May–August temperature, ranging from 0.63 to 0.84. The highest accumulation-season correlation coefficient is total accumulation-season precipitation, ranging from 0.35 to 0.59.
Measurement of ice-sheet topography using satellite-radar interferometry
Authors: Joughin Ian , Winebrenner Dale , Fahnestock Mark , Kwok Ron , Krabill William 
Published: September 2017

AbstractDetailed digital elevation models (DEMs) do not exist for much of the Greenland and Antartic ice sheets. Radar altimetry is at present the primary, in many cases the only, source of topographic data over the ice sheets, but the horizontal resolution of such data is coarse. Satellite-radar interferometry uses the phase difference between pairs of synthetic aperture radar (SAR) images to measure both ice-sheet topography and surface displacement. We have applied this technique using ERS-1 SAR data to make detailed (i.e. 80 m horizontal resolution) maps of surface topography in a 100 km by 300 km strip in West Greenland, extending northward from just above Jakobshavns Isbræ. Comparison with а 76 km long line of airborne laser-altimeter data shows that We have achieved a relative accuracy of 2.5 m along the profile. These observations provide a detailed view of dynamically Supported topography near the margin of an ice sheet. In the final section We compare our estimate of topography with phase contours due to motion, and confirm our earlier analysis concerning vertical ice-sheet motion and complexity in ERS-1 SAR interferograms.
Instruments and methods: Submersible remotely operated vehicles (ROVs) for investigations of the glacier-ocean-sediment interface
Authors: Dowdeswell Julian A. , Powell Ross D. 
Published: September 2017

AbstractSubmersible remotely operated vehicles (ROVs) are valuable research tools for data collection in dangerous or inaccessible environments associated with glaciers terminating in the sea. At tide-water ice cliffs, iceberg calving makes close approaches for extended time periods In manned vessels dangerous. ROVs can be operated from relatively safe distances (hundreds of metres); they can also descend to considerably greater depths (hundreds rather than tens of metres) than scuba diving permits. They can provide data on glacier grounding-line and sea-floor morphology and water-column characteristics (e.g. salinity, turbidity, current velocity). They are also used for. diving under floating glacier tongues and ice shelves where no other access is possible. They can be fitted with a variety of oceanographic sensors, imaging sensors, tracking devices and water and sediment samplers, making them versatile research instruments that can supply qualitative and quantitative data for process studies in logistically difficult environments.
Pleistocene Ice at the Base of the Barnes Ice Cap, Baffin Island, N.W.T., Canada
Authors: Leb. Hooke Roger 
Published: September 2017

AbstractOxygen-isotope ratios indicate that a distinctive band of white ice along the margin of the Barnes Ice Cap is of Pleistocene age. It is estimated freom a flow mogerl that beneath the center of the ice cap the thickness of the band shuuld be abont 0.6 times its thickness at the margin, or about 8 m. However, an ingerpengernt estimate, based on calculated vertical strain-rates and explicitly assuming no basal melting, predicts a thickness of about 22 m beneath the center of the ice cap. The discrepancy between the two thickness estimates is interpreted as indicating that basal melting has occurred. Calculated basal temperatures support this conclusion.
On the Hypothesis of Ice Ages Suggested by Captain E. S. Gernet
Authors: Chizhov O. P. 
Published: September 2017

This paper is devoted to the causes of initiation and development of the Quaternary glaciation and climatic fluctuations connected with it. There are many hypotheses on this problem. The most interesting of them are those suggesting the evolution of glaciers and ice sheets, and variation of climate as a self-regulating process.The first person to offer a definite mechanism for such self-regulation was the Russian sailor, Captain E. S. Gernet, whose book about this was published in 1930. The book is of great scientific importance, but so far few people appear to have known anything about it. This paper gives a brief summary of the book, shows the similarity between the main ideas of Captain Gernet and the American geologists, W. L. Stokes, M. Ewing and W. L. Donn (the theory of the two latter authors has become well known recently), and justifies naming this concept after Gernet and Stokes in honour of the men who first proposed it.
Snow-Slope Stabili1y – A Probabilistic Approach
Authors: Conway H. , Abrahamson J. 
Published: September 2017

AbstractMeasurements of snow properties across and down snow slopes have been used to calculate a safety margin — the difference between the basal shear strength and the applied static stress. Areas of basal deficit exist when the applied shear stress exceeds the basal shear strength (the safety margin is negative), and basal areas are pinned when the safety margin is positive. As the size of deficit increases, stresses within the overlying slab also increase, and these may be sufficient to cause an avalanche.Measurements made on five slopes (four of which had avalanched) were characterized by considerable spatial variability, and the safety margin has been treated as a random function which varies over the slope. Statistical models of Vanmarcke (1977[a], 1983) have been applied to determine the most likely size of deficit required for avalanching (95% confidence). In one case, an avalanche occurred when the length of deficit was only 2.9 m, and in the other cases the length was always less than 7 m. This size of deficit is small compared with the total area of many avalanche slopes which suggests that avalanches initiate from small zones of deficit, and makes it difficult to locate a deficit with just a few tests.The optimum sampling interval and number of tests required to yield an adequate estimate of the statistical parameters of the safety margin are also discussed.
Bed Topography and Mass-Balance Distribution of Columbia Glacier, Alaska, U.S.A., Determined from Sequential Aerial Photography
Authors: Rasmussen L. A. 
Published: September 2017

AbstractAn internally consistent data set of geometry and flow variables for the lower part of Columbia Glacier, south-central Alaska, is derived entirely from vertical aerial photography. The principle of mass conservation is imposed on the data in the form of a centered finite-difference approximation of the continuity equation. It is applied on a 120-node section of a square grid covering the 15 km long, high-velocity stretch ending at the grounded, heavily calving terminus of this large glacier.Photography was obtained 22 times between June 1977 and September 1981. Surface altitudes on the dates of the flights and the displacement vectors between pairs of flights were determined photogrammetrically. Natural features on the glacier surface were sufficiently prominent and enduring to be followed from the date of one flight to the next.Because both the altitude points and displacement vectors were irregularly positioned spatially, interpolation was necessary to get values on the grid nodes. The points had already been subjected to the method of optimum interpolation to get surface altitudes on the grid nodes. The displacement vectors are subjected here to a constrained–interpolation method to get velocity vectors at the grid nodes that are consistent, through the continuity equation, with the other variables.The other variables needed to achieve closure of the variable set are bed topography and mass-balance distribution. The latter was taken to be a separate linear function of altitude for each time interval. Values for bed altitudes at 120 nodes and two coefficients of each 21 balance functions were inferred as the 162 model parameters in a non-linear minimization problem having 4305 observed velocity components as its data.
Snaefell, East Iceland
Authors: Jennings J. N. 
Published: September 2017

AbstractThe morphology of Snaefell, East Iceland, and the state of its glaciers in 1937 are described. There are four small glaciers. Two of these exist in well-developed cirques incised into the lavas, tuffs and breccias of this Pleistocene volcano. The third receives ice from a summit ice cap, while the fourth also receives ice from the same source as well as lying in a cirque. The firn line in 1937 is put between 1350 and 1500 m. so that the mass balance of the glaciers is unlikely to have been favourable, although only one showed any abandoned moraines. An explanation of the varying glacial modification of the different slopes of Snaefell is suggested in terms of structural trends, shading from the sun and snow-drifting.
Brittle Fracture of Ice at 77 K
Authors: Parameswaran V. R. , Jones Stephen J. 
Published: September 2017

AbstractLaboratory-grown single crystals, both pure and HF-doped, and pure polycrystals of ice, as well as natural, columnar-grained ice from the River St Lawrence, have been deformed in uniaxial compression at 77 K at strain-rates between 10-5 and 10-3 s-1. Brittle fracture was observed, with stress-strain curves similar to those found for rocks at room temperature. The first cracks appeared at low stresses, ≈0.3 MN m-2, in agreement with theory, but the failure or fracture stress was high ≈50 MN m-2. The ratio of experimental to theoretical strength was o.28. HF doping of the single crystals had no effect at this temperature.
Fitting Formulae and Constraints for the Existence of S-type and P-type Habitable Zones in Binary Systems
Authors: Wang 王兆 Zhaopeng 鹏 , Cuntz Manfred 
Published: September 2017

Abstract
We derive fitting formulae for the quick determination of the existence of S-type and P-type habitable zones (HZs) in binary systems. Based on previous work, we consider the limits of the climatological HZ in binary systems (which sensitively depend on the system parameters) based on a joint constraint encompassing planetary orbital stability and a habitable region for a possible system planet. Additionally, we employ updated results on planetary climate models obtained by Kopparapu and collaborators. Our results are applied to four P-type systems (Kepler-34, Kepler-35, Kepler-413, and Kepler-1647) and two S-type systems (TrES-2 and KOI-1257). Our method allows us to gauge the existence of climatological HZs for these systems in a straightforward manner with detailed consideration of the observational uncertainties. Further applications may include studies of other existing systems as well as systems to be identified through future observational campaigns.
Analyzing Exoplanet Phase Curve Information Content: Toward Optimized Observing Strategies
Authors: Placek Ben , Angerhausen Daniel , Knuth Kevin H. 
Published: September 2017

Abstract
Secondary eclipses and phase curves reveal information about the reflectivity and heat distribution in exoplanet atmospheres. The phase curve is composed of a combination of reflected and thermally emitted light from the planet, and for circular orbits the phase curve peaks during the secondary eclipse or at an orbital phase of 0.5. Physical mechanisms have been discovered that shift the phase curve maximum of tidally locked close-in planets to the right, or left, of the secondary eclipse. These mechanisms include cloud formations and atmospheric superrotation, both of which serve to shift the thermally bright hot-spot or highly reflective bright spot of the atmosphere away from the sub-stellar point. Here, we present a methodology for optimizing observing strategies for both secondary eclipses and phase curves with the goal of maximizing the information gained about the planetary atmosphere while minimizing the (assumed) continuous observation time. We show that we can increase the duty cycle of observations aimed at the measurements of phase curve characteristics (amplitude, phase offset) by up to 50% for future platforms such as CHaracterising ExOPlanets Satellite (CHEOPS) and JWST. We apply this methodology to the test cases of the Spitzer phase curve of 55-Cancri-e, which displays an eastward shift in its phase curve maximum as well as model-generated observations of an ultra-short period planet observed with CHEOPS.
« Professions des parents ? Loisirs ? Projet ? ». Pratiques et regards croisés d’enseignants et d’élèves sur les fiches de renseignements
Authors: Murillo Audrey , Blanc Julie , Veyrac Hélène , Sahuc Philippe 
Published: September 2017

L’article porte sur les tout premiers cours de l’année scolaire, en lycée, lorsque les enseignants demandent aux élèves de se présenter, soit à l’oral, soit à l’écrit par le biais de fiches de renseignements. En convoquant une approche interactionniste et ergonomique, nous nous intéressons à l’activité des enseignants et des élèves, lors de ces moments de présentations. Nous montrons que les enseignants prennent des informations sur les élèves, informations qui font instrument pour eux. En prenant ces informations, les enseignants s’attachent à préserver la face des élèves : leurs prises d’informations sont ainsi parfois empêchées, déguisées, facultatives, non normatives, ou encore privées. Toutefois, les élèves sont parfois mis dans l’embarras par les questions posées par leurs enseignants, et cherchent à préserver leur face. Enfin, nous nous attachons à croiser les regards entre enseignants et élèves, et montrons que la clairvoyance des uns sur l’activité des autres est limitée.
Lipschitz 1-connectedness for Some Solvable Lie Groups
Authors: Cohen David Bruce 
Published: September 2017

AbstractA space X is said to be Lipschitz 1-connected if every Lipschitz loop 𝛾 : S
1 → X bounds a O (Lip(𝛾))-Lipschitz disk f : D
2 → X. A Lipschitz 1-connected space admits a quadratic isoperimetric inequality, but it is unknown whether the converse is true. Cornulier and Tessera showed that certain solvable Lie groups have quadratic isoperimetric inequalities, and we extend their result to show that these groups are Lipschitz 1-connected.
Elements of -algebras Attaining their Norm in a Finite-dimensional Representation
Authors: Courtney Kristin , Shulman Tatiana 
Published: September 2017

AbstractWe characterize the class of RFD $C^{\ast }$-algebras as those containing a dense subset of elements that attain their norm under a finite-dimensional representation. We show further that this subset is the whole space precisely when every irreducible representation of the $C^{\ast }$-algebra is finite-dimensional, which is equivalent to the $C^{\ast }$-algebra having no simple infinite-dimensional AF subquotient. We apply techniques from this proof to show the existence of elements in more general classes of $C^{\ast }$-algebras whose norms in finite-dimensional representations fit certain prescribed properties.