bluuebunny/crossref_metadata_2025_split huggingface dataset:
Flux of debris transported by ice at three Alaskan tidewater glaciers
Authors: Hunter Lewis E. , Powell Ross D. , Lawson Daniel E. 
Published: September 2017

AbstractThe stability of a tidewater terminus is controlled by glacial dynamics, calving processes and sedimentary processes at the grounding line. An investigation of grounding-line sediment dynamics and morainal-bank sediment budgets in Glacier Bay, Alaska, U.S.A., has yielded data that enable us to determine the debris fluxes of Grand pacific, Margerie and Muir Glaciers. Debris flux ranges from 105 to 106 m3 a−1, one to two orders of magnitude lower than the glacifluvial sediment fluxes (106−107 m3 a−1). Combined, these fluxes represent the highest yields known for glacierized basins. Large debris fluxes reflect the combined effects of rapid glacier flow, driven by the maritime climate of southeast Alaska, and highly erodible bedrock. Englacial-debris distribution is affected by valley width and relief, both of which control the availability of sediment. The number of tributaries controls the distribution and volume of debris in englacial and supraglacial moraines. At the terminus, iceberg-rafting removes up to two orders of magnitude more sediment from the ice-proximal environment than is deposited by melt-out or is dumped during calving events. Rough estimates of the sediment flux by deforming beds suggests that soft-bed deformation may deliver up to an order of magnitude more sediment to the terminus than is released from within the glacier ice.
Study of an Ice Core to the Bedrock in the Accumulation zone of an Alpine Glacier
Authors: Vallon M. , Petit J.-R. , Fabre B. 
Published: September 2017

AbstractA water table appearing every summer where the ice begins, at a gerpth of approximately 30 m, accelerates the transformation of firn into ice during the summer (80% of the ice formed every year appears in less than 2 months). The ice formed in this way contains from 0 to 0.6% water. The average water content increases gradually with the gerpth because of the heat of gerformation. But, near bedrock, between 180 and 187 m, the permeability of the blue ice is such that the water content drops (0.3% as compared to 1.3% between 160 and 180 m).From a gerpth of 33 m, a foliation of sedimentary origin gradually gervelops in the ice. Its dip increases regularly to a gerpth of 145 m. At 145 m it jumps sudgernly freom 20° to 40°, then at 170 m freom 40° to 65°, which can be explained by old modifications in the bergschrund. This foliation disappears near bedrock (180-187 m), where there are no bubbles in the ice.The average size of an ice crystal increases slowly in the firn, shows seasonal fluctuations between 30 and 50 m, then jumps freom a diameter of 1 or 2 mm to 10 or 20 mm between 50 and 80 m. Between 180 and 187 m, the ice is mager of large crystals (3-10 cm diameter; the figure, however, is probably inexact due to a recrystallization of the samples).The very strong sub-vertical orientation of the optic axes of the firn crystals disappears quickly, and freom 66 m on, in ice with large crystals, a fabric of multiple maxima appears (generally, 3 or 4 directions, forming a triangle or a rhombus). On the other hand, in the small crystals that form bands parallel to the plane of foliation, only one direction of preferential orientation can be seen, or two close to one another. Crystals of intermediate size (10 to 50 mm) generally have two directions of preferred orientation at an angle of approximately 50° to one another. No matter how big the crystals are, the angle between the most common c-axis orientation and the vertical does not change freom 60 to 170 m gerpth.
Resurvey of the “Byrd” Station, Antarctica, Drill Hole
Authors: Garfield D. E. , Ueda H. T. 
Published: September 2017

AbstractThe drill hole at “Byrd” station, which was completed in January 1968 to a vertical gerpth of 7 063 ft (2 153 m) below the top of the hole casing, was resurveyed in January 1975 to a vertical gerpth of 4 835 ft (1 474 m)· Inclination and azimuth measurements were mager with a Parsons multiple shoe inclinometer and compared with the earlier measurements mager during drilling. The results indicate a progressively increasing displacement with gerpth to a value of 51.2 ft (15.6 m) or about 7.3 ft/year (2.23 m/year) at the 4 835 ft (1 474 m) level. The direction of movement relative to the surface varies freom south-west at 300 ft (91.5 m) to north-east at 1 100 ft (335 m) to east at 3 368 ft (1 027 m) to north-east at 4835 ft (l 474 m), indicative of a complex twisting motion. An increase in accessible gerpth along the hole axis of 18 ft (549 m) beyond the 1969 gerpth was noted. No attempt was mager to measure hole diameter or vertical strain. It is recommengerd that the hole be resurveyed in 3-5 years if it is still logistically feasible, using a more up-dated inclinometer.
Radio-echo Sounding of Temperate Glaciers: Ice Properties and Sounder Design Criteria
Authors: Watts Raymond D. , England Anthony W. 
Published: September 2017

AbstractThis is the first paper in a two-part series which gerscribes the gersign, operation, and testing of a successful 5 MHz radio-echo soungerr for temperate glaciers. This part gerals with the electromagnetic characteristics of temperate glaciers at radio freequencies. Earlier workers' problems in sounding through temperate ice are explained in terms of electromagnetic scattering by water-filled voids. The freequency gerpengernce of the scattering indicates that returns freom scatterers diminish rapidly at freequencies below about 10 MHz. A system with the following characteristics is recommengerd: a transmitted pulse with a center freequency of about 5 MHz, duration of about 1 cycle, and a receiver which is untuned and which measures field intensity rather than power. Spectral methods for studying the size distribution of scatterers are presented. An actual instrument and field trials will be gerscribed in a forthcoming publication by R. S. Vickers and R. Bollen.
Pleistocene Glaciation in Ethiopia: New Evidence
Authors: Potter E. C. 
Published: September 2017

AbstractGeomorphological evigernce indicates that Mount Badda, Ethiopia, had a Pleistocene ice cap of at least 140 km2. Altituger of the snow line was probably about 4 000 m, only 350 m below the summit, suggesting that glaciation occurred during the Würm glacial maximum.
Bubbles and Bubble Pressures in Antarctic Glacier Ice
Authors: Gow Anthony J. 
Published: September 2017

Application of the gas law to fourth-place density measurements of ice samples from two deep drill holes at “Byrd” station and “Little America V”, Antarctica, shows that virtually all density increase beyond the pore close-off density (0.830 g cm−3) can be attributed to compression of the entrapped bubbles of air. Data from “Byrd” station also indicate that the lag between overburden pressure and bubble pressure, initially 4–5 kg cm−2 at pore close-off, diminishes to less than 1.0 kg cm−2 at about 200 m depth. By substituting the overburden pressure for the bubble pressure in the pressure-density relationship based on the gas law, one can determine ice densities below 200 m more accurately than they can be measured per se on cores, because of the relaxation that occurs in samples recovered from high confining pressures. This relaxation, resulting in a progressive increase in the bulk volume of the ice with time, is generally attributed to decompression of the entrapped air bubbles following removal of the ice from high confining pressures. However. calculations of the stress in ice due to bubble pressure, together with measurements of bubble sizes in cores from various depths at “Byrd” station, both tend to indicate that there has been negligible decompression of the inclosed bubbles. It is suggested that most of this relaxation may be due to the formation of micro-cracks in the ice. Anomalous bubble pressure–density relations at “Little America V” tend to confirm abundant petrographic evidence of the existence of considerable deformation in the upper part of the Ross Ice Shelf.Studies of crystal–bubble relations at “Byrd” station revealed that the concentration of bubbles in ice remains remarkably constant at approximately 220 bubbles/cm3. Bubbles and crystals were found to be present in approximately equal numbers at pore close-off at 64 m depth, at which level the average bubble diameter was 0·95 mm, decreasing to 0.49 mm at 116 m and to 0·33 mm at 279 m. Despite a ten-fold increase in the size of crystals between 64 and 279 m, the bubbles showed no tendency to migrate to grain boundaries during recrystallization of the ice. The observation that most of the bubbles had assumed substantially spherical shapes by 120 m depth points to essentially hydrostatic conditions in the upper layers of the ice sheet at “Byrd” station.
The Complexities of the Three-Dimensional Shape of Individual Crystals in Glacier Ice
Authors: Rigsby George P. 
Published: September 2017

A block of ice from Blue Glacier. Washington, was successively sectioned at close intervals as a means of determining exact crystal shape in three dimensions. Two crystals occupying over 20 per cent of the entire sample are used as examples, and their volumes calculated. These crystals were found to be much larger and more complex in shape than expected from thin-section examination alone. The surface-to-volume ratio was calculated using a simple relationship between the length of lines in a grid crossing the crystal and grid-line intercepts with the crystal boundary. From this ratio the surface area of each crystal was calculated.A measurement of irregularity or jaggedness is introduced in order to compare crystals of different size with one another. This is necessary because surface-to-volume ratio of a body of the same shape decreases as the size increases.
The Dynamics of Temperate Glaciers from the Detailed Viewpoint
Authors: Lliboutry L. 
Published: September 2017

The stresses and strains in a limited region of a temperate glacier are approximated by polynomials. In this case it seems that we can replace Glen’s law by the more convenient law . We initially consider a plane problem with a flat glacier surface. In a simple example the theoretical possibility of very important deviations from the classical relation τxz = ρgz sin α is demonstrated. The calculation is then extended to the more general case when the surface of the glacier is no longer a plane (the contours remaining always parallel) and where the width of the glacier varies.Starting from a precise survey of the surface and measurements of surface velocity, one can then obtain velocities and stresses at depth, and extrapolate the bedrock profile into regions inaccessible by seismic sounding. A provisional calculation has been made for the ice fall between the Glacier du Géant and the Glacier du Tacul (Mont-Blanc massif). In the lower part, the existence of a gorge near the right bank and the fact that the various ice streams partially superpose instead of flowing side by side, make the calculations uncertain.In this way the law of friction can be determined experimentally. Proceeding down-glacier, the sliding velocity decreases from about 830 m/year to about 250 m/year, while the normal pressure increases from about 2.8 to about 18.5 bar. At the same time the friction increases from about 1.1 to about 4.3 bar, approximately proportional to the pressure, which seems to be in agreement with the author’s theory of friction.
Structure and Flow in the Margin of the Barnes Ice Cap, Baffin Island, N.W.T., Canada
Authors: Hooke Roger Leb. 
Published: September 2017

The structure and flow field in the margin of the Barnes Ice Cap was determined through observations on the ice-cap surface, in four bore holes, and in a 125 m ice tunnel. A band of fine bubbly white ice with a single maximum fabric appears at the glacier surface about 160 m from the margin. This band is overlain by coarse blue ice with a four-maximum fabric, and underlain by alternating bands of fine ice with a single-maximum fabric and moderately coarse ice with a two or three-maximum fabric.The effective strain rate was determined from the bore-hole and tunnel deformation data, and possible variations in the other three parameters in Glen’s flow law, , were studied. It appears that τxy is independent of depth near the surface, and that relative to the coarse blue ice, A is 40 to 50% lower in the white ice and possibly 10% lower in the fine blue ice.Dips of foliation planes decrease rapidly with increasing depth and distance from the margin. This foliation is assumed to have developed near and parallel to the bed some distance from the margin. An analysis based on this assumption predicts the observed change in dip, but suggests that it did not develop under the present flow field. The ice cap was probably thicker a few tens of years ago, and the observed foliation pattern may be a relict from that time.
Mesoscale Strain Measurements on the Beaufort Sea Pack Ice (Aidjex 1971)
Authors: Hibler W. D. , Weeks W. F. , Ackley S. , Kovacs A. , Campbell W. J. 
Published: September 2017

AbstractThe deformation of a strain triangle (≈6 km × 8 km × 11 km) located on first-year ice in the Beaufort Sea was observed over a two-week period in March 1971. Significant strain events (≈ 1.5%) were observed to occur during short (≈6 h) time periods. The long-term (one day or more) divergence rate varied between 0.04 and 0.08 × 10−3 h−1. Short-term divergence rates showed values as high as 0.29 × 10−3 h−1. The observed shearing motion indicated that the floes to the east were moving to the south relative to the floes to the west. This agrees with the shear pattern that might be expected considering the location of the station in the Pacific Gyre. Studies of fracture (lead and crack) orientations in the vicinity of the strain triangle indicate reasonable correlations with the orientation of the strain-rate ellipse. A qualitative relation is suggested between the fracture density and the long-term divergence rate. Correlations were also observed between the divergence of the wind field as computed from the surface pressure field and the ice divergence.
Evolution of Variegated Glacier, Alaska, U.S.A., Prior to its Surge
Authors: Raymond C. F. , Harrison W. D. 
Published: September 2017

AbstractDuring the decade prior to its 1982–83 surge, Variegated Glacier experienced progressive changes in geometry and velocity. It thickened in the upper 60% and thinned in the lower 40% of its 20 km length. Thickness changes were up to 20%. Annual velocity increased by up to 500%, reaching a maximum of 0.7 m d−1 in the year before surge onset. Amplitude of seasonal variation in velocity increased up to 0.3 m d−1 by 1978, but did not increase markedly after that. The changes in velocity were larger than predicted from changes in deformation rate caused by changes in shear stress and depth. This anomalous velocity was especially large after 1978 in the zone of thickening on the upper glacier. If it is assumed to arise from basal sliding, the inferred pattern of sliding shows qualitative features consistent with a direct effect from basal shear stress and an inverse effect from effective normal stress. A drop in effective normal stress in a zone of decreasing surface slope up-glacier from the largest thickness increase may have been significant in the initiation of surge motion in 1982.
Identification of Chernobyl Fall-Out as a New Reference Level in Northern Hemisphere Glaciers
Authors: Pourchet M. , Pinglot J. F. , Reynaud L. , Holdsworth G. 
Published: September 2017

AbstractAmong the various artificial radioactive markers (mainly from atmospheric nuclear tests), the contamination from the Chernobyl accident has been found at five sampling sites on Northern Hemisphere glaciers. Total beta-activity measurements reveal a very high radio-active level. However, due to the short time of its occurrence, the temporal resolution of this event in the snow layers can be generally quite low and positive results require careful sampling. The size of the signal also depends on the trajectory of the contaminant cloud, the amount of precipitation, and the surface conditions during deposition.
A High Resolution Survey of the Galactic Plane at 408 MHz
Authors: Tung A. K. , Kothes R. , Landecker T. L. , Geisbüsch J. , Rizzo D. Del , Taylor A. R. , Brunt C. M. , Gray A. D. , Dougherty S. M. 
Published: September 2017

Abstract
The interstellar medium is a complex “ecosystem” with gas constituents in the atomic, molecular and ionized states, dust, magnetic fields, and relativistic particles. The Canadian Galactic Plane Survey has imaged these constituents at multiple radio and infrared frequencies with angular resolution of the order of arcminutes. This paper presents radio continuum data at 408 MHz over the area of

,

, with an extension to

in the range of

, with angular resolution

cosecδ. Observations were made with the Synthesis Telescope at the Dominion Radio Astrophysical Observatory as part of the Canadian Galactic Plane Survey. The calibration of the survey using existing radio source catalogs is described. The accuracy of 408 MHz flux densities from the data is 6%. Information on large structures has been incorporated into the data using the single-antenna survey of Haslam et al. The paper presents the data, describes how it can be accessed electronically, and gives examples of applications of the data to ISM research.
Weighing Uranus’ Moon Cressida with the η Ring
Authors: Chancia Robert O. , Hedman Matthew M. , French Richard G. 
Published: September 2017

Abstract
The η ring is one of the narrow rings of Uranus, consisting of a dense core that is 1–2 km wide and a diffuse outer sheet spanning about 40 km. Its dense core lies just exterior to the 3:2 Inner Lindblad Resonance of the small moon Cressida. We fit the η ring radius residuals and longitudes from a complete set of both ground-based and Voyager stellar and radio occultations of the Uranian rings spanning 1977–2002. We find variations in the radial position of the η ring that are likely generated by this resonance, and take the form of a 3-lobed structure rotating at an angular rate equal to the mean motion of the moon Cressida. The amplitude of these radial oscillations is 0.667 ± 0.113 km, which is consistent with the expected shape due to the perturbations from Cressida. The magnitude of these variations provides the first measurement of the mass and density of the moon Cressida (

kg and

g cm−3) or, indeed, any of Uranus’ small inner moons. A better grasp of inner Uranian satellite masses will provide another clue to the composition, dynamical stability, and history of Uranus’ tightly packed system of small moons.
The Interior Angular Momentum of Core Hydrogen Burning Stars from Gravity-mode Oscillations
Authors: Aerts C. , Reeth T. Van , Tkachenko A. 
Published: September 2017

Abstract
A major uncertainty in the theory of stellar evolution is the angular momentum distribution inside stars and its change during stellar life. We compose a sample of 67 stars in the core hydrogen burning phase with a

value from high-resolution spectroscopy, as well as an asteroseismic estimate of the near-core rotation rate derived from gravity-mode oscillations detected in space photometry. This assembly includes 8 B-type stars and 59 AF-type stars, covering a mass range from 1.4 to 5 M
⊙, i.e., it concerns intermediate-mass stars born with a well-developed convective core. The sample covers projected surface rotation velocities

km s−1 and core rotation rates up to 26 μHz, which corresponds to 50% of the critical rotation frequency. We find deviations from rigid rotation to be moderate in the single stars of this sample. We place the near-core rotation rates in an evolutionary context and find that the core rotation must drop drastically before or during the short phase between the end of the core hydrogen burning and the onset of core helium burning. We compute the spin parameter, which is the ratio of twice the rotation rate to the mode frequency (also known as the inverse Rossby number), for 1682 gravity modes and find the majority (95%) to occur in the sub-inertial regime. The 10 stars with Rossby modes have spin parameters between 14 and 30, while the gravito-inertial modes cover the range from 1 to 15.
The Value of the Frontalis Suspension Procedure as a Repeat Intervention in Congenital Blepharoptosis
Authors: Ural Özlem , Mocan Mehmet C. , Erdener Ugur 
Published: September 2017

Purpose:
To evaluate the therapeutic benefits of frontalis suspension as a repeat intervention in congenital blepharoptosis.

Methods:

Pediatric patients diagnosed as having congenital ptosis who had at least 2 years of postoperative follow-up were included in this retrospective study. A successful outcome was defined as a postoperative margin-reflex distance of 3 mm or greater. The chi-square, Student's
t
, and Mann–Whitney
U
tests were used in comparisons.

Results:

Eighty-four eyes of 77 patients with a follow-up period of 8.4 ± 0.7 years were included. The initial surgery was levator resection in 29 (34.5%) eyes and frontalis suspension in 55 (65.5%) eyes. Frontalis suspension was performed for all repeat interventions (n = 20). Surgical success was achieved in 61.9% of patients with single surgery (75.9% for levator resection vs 54.5% for frontalis suspension;
P
= .06) and in 77.4% of patients following repeated surgeries (93.1% vs 69.1% for patients who initially underwent levator resection vs frontalis suspension, respectively;
P
= .012). A higher success rate was associated with better preoperative levator function (
P
= .01) and a higher margin-reflex distance (
P
= .004), and was inversely proportional to ptosis severity (
P
= .04).

Conclusions:
Frontalis suspension as a repeat intervention for congenital blepharoptosis is associated with a further increase in long-term anatomic success rates and should be considered when initial procedures fail or remain inadequate.

[
J Pediatr Ophthalmol Strabismus
. 2017;54(5):320–323.]
L’inscription paradoxale du dispositif Diwan en Bretagne
Authors: Balcou-Debussche Maryvette , Tupin Frédéric 
Published: September 2017

Cette contribution interroge l’inscription sociale du dispositif bilingue Diwan en Bretagne, près de 40 ans après les débuts d’un projet qui soutient le choix de l’immersion totale en langue bretonne, dans un contexte régional où le nombre de locuteurs « naturels » ne cesse de baisser. Envisagée dans ses dimensions « hors-sol », l’intervention éducative est questionnée ici à travers ses dimensions didactiques, psychopédagogiques, organisationnelles, institutionnelles et sociales. Les analyses prennent appui sur 48 entretiens semi-directifs menés auprès des équipes de direction, des enseignants, des élèves et des parents d’élèves, ainsi que sur des observations in situ réalisées dans 10 établissements. Les résultats permettent de mettre en exergue les points d’appui sur lesquels le dispositif s’est construit, mais ils soulignent aussi les lieux de tensions et de controverses, tant du côté des actions et des acteurs eux-mêmes que du côté des orientations privilégiées par ces derniers.