bluuebunny/crossref_metadata_2025_split huggingface dataset:
New precipitation and accumulation maps for Greenland
Authors: Ohmura Atsumu , Reeh Niels 
Published: September 2017

AbstractAnnual total precipitation and the annual accumulation on the Greenland ice sheet are evaluated and presented in two maps. The maps are based on accumulation measurements of 251 pits and cores obtained from the upper accumulation zone and precipitation measurements made at 35 meteorological stations in the coastal region. To construct the accumulation map, the annual precipitation was split into solid and liquid precipitation components. Annual total precipitation exceeding 2500mmw.e. occurs on the southeastern tip of Greenland, while the minimum precipitation is estimated to occur on the northeastern slope of the ice sheet. The mean annual precipitation for all of Greenland is 340 mm w.e. The largest annual accumulation of about 1500 mm w.e. is found on the glaciers in the southeastern corner of Greenland, while the smallest accumulation is found on the northeastern slope of the ice sheet west of Danmarkshavn. The mean accumulation on the Greenland ice sheet is estimated at 310mmw.e. The regional difference in accumulation is examined with respect to the 850hPa(mbar) level circulation. The present surface topography is found to play an important role in determining regional accumulation on the ice sheet.
Butyl acetate, an alternative drilling fluid for deep ice-coring projects
Authors: Gosink T.A. , Kelley J.J. , Koci B.R. , Burton T.W. , Tumeo M.A. 
Published: September 2017

AbstractDeep-drilling operations in glaciers require a fluid to maintain hydrostatic equilibrium and prevent closure due to plastic flow of the ice. Many past practices have employed various fluid mixtures using fuel oil as the base. The case for butyl acetate is presented here as an adequately dense and environmentally safe drilling fluid. Results from the 1990 drill season are highly favorable.
Ice Floes in Collision
Authors: Weber J. R. 
Published: September 2017

AbstractAn event recorded by a biaxial tilt-meter during a storm at the camp of the AIDJEX Pilot Study located on the pack ice in the Beaufort Sea in 1972 is interpreted as an acceleration caused by the collision of a faster drifting ice floe with the station floe. It is estimated that the acceleration lasted between 20 and 40 s and resulted in a velocity increase of between 84 and 120 m/h. The energy imparted per square kilometer to the station floe during collision is estimated to be between 5.7 and 8.1 MJ.The station was equipped with an acoustic bottom reference (ABR) system with a sampling rate of one minute. However, the positional scatter is too large and the sample rate too low to be able reliably to identify the collision event from the ABR data alone.
Testing of Radiometric Detection of Avalanche Victims
Authors: Coumes A. , Liva V. , Zadworny F. 
Published: September 2017

AbstractA radiometer prototype has been constructed using the S band. In this band, a theoretical evaluation of the differences of temperature which are measurable by the radiometric method proves the influence of the parameters liquid-water content of snow and snow thickness.When there is no victim, the apparent temperature of a snow layer depends on these parameters and presents important variations because of its natural inhomogeneity. In order to detect the local variation of the apparent temperature due to the presence of a victim, we must refer to an average local temperature obtained by a servo-system. Thus, we obtain a certain number of false alarms which can be suppressed only with a manual sounding. The search itself becomes very long and also requires a systematic exploration of the snow surface by parallel traverses spaced every 2 m. This exploration seems impossible on uneven ground such as a real avalanche area.
Avalanche Activity in Iceland, Climatic Conditions, and Terrain Features
Authors: Björnsson Helgi 
Published: September 2017

AbstractAbstract. Avalance activity in Iceland for the last 860 years is briefly outlined and the present avalanche problems in Iceland are explained. Statistics are given for the number of deaths from avalanches by years, months and avalanche categories (for both residents and travellers).Climatic conditions and terrain features are described for the main avalanche-hazard areas in Iceland. Data from meteorological stations for precipitation, wind, and air temperatures have been analysed for all the major avalanche cycles in the present century. Synoptic weather patterns that trigger avalanches are explained. A distinction is made between conditions that cause wet and dry avalanches. The results form the basis of an area-wide avalanche forecast in Iceland.
Avalanche Hazard in the Cairngorm Mountains, Scotland
Authors: Ward R. G. W. 
Published: September 2017

AbstractAvalanche accidents are increasing in Scotland and fatalities now average two each year. The victims are either mountaineers or cross-country skiers as the problem is confined to the steeper and remoter slopes. Studies in the Cairngorm Mountains have shown that Scottish snow differs from alpine snow in three respects: depth hoar does not occur in Scotland, higher values are found for density and rammsonde penetration, and ice layers are more abundant. Slab avalanches are found on slopes of about 35° and sluffs on slopes of 30° and steeper. Although most avalanches are small, crown fracture lines reach a maximum length of 500 m, and slabs may be up to eight metres thick. Preliminary correlations between avalanche release and weather conditions have shown the importance of cold periods following heavy snow falls and the significance of thaws. Much more needs to be done before an avalanche-forecasting service could be provided, not the least of which is persuading likely beneficiaries that such a service would be worthwhile.
Techniques for Thermal Conductivity Measurements in Antarctica
Authors: Ewing Richard E. , Falk Richard S. , Bolzan John F. , Whillans Ian M. 
Published: September 2017

An accurate knowledge of the thermal properties of firn and ice within a glacier is essential for any reliable mathematical model of heat transfer. This paper considers the problem of determining the thermal properties of firn at Dome C, Antarctica, for use in such a model.First, the difficulties in accurately determining thermal properties are discussed. Then a physical experiment which can be performed under field conditions, but which will yield a well-posed mathematical problem for determining the unknown properties, is presented. Next, two different numerical techniques for solving the mathematical problem are discussed. Finally, some numerical approximations and error estimates are presented for the results of applying our numerical procedure to data from Dome C. Although insufficient data were obtained to test our methods fully, we have established a measurement procedure and a method of analysis which appear to be promising.
Recent Variations in Heavy Metal Concentrations in Firn and Air From the Antarctic Peninsula
Authors: Peel D. A. , Wolff E. W. 
Published: September 2017

A snow-pit and hand-drilled core have been sampled at Spaatz Island in the Antarctic Peninsula to obtain evidence on the importance of short-term fluctuations of heavy metal (Cd, Cu, Pb, and Zn) concentrations. A programme of air sampling was undertaken at the same time to investigate directly the link between concentrations in air and in snow. The snow samples and air filters have been analysed by atomic absorption spectrometry (AAS) following preconcentration on tungsten wires and by differential pulse anodic stripping voltammetry (DPASV). One sequence of snow samples was preconcentrated in the field and analysed later for Cd in the laboratory.The snow analyses confirm that year-to-year variations in heavy metal concentrations may be comparable with changes due to long-term variations in global emission rates to the atmosphere from industrial sources. The importance of understanding these apparently meteorologically controlled processes is underlined. Averaged data from the combined air/snow sampling programme show a satisfactory linear relationship between concentrations in air and in snow for both the heavy metals and for the cation component of the marine aerosol. The results, considered in the light of Junge's model for static rainout, give a ratio for concentration in air (ng m−3)/concentration in snow (ng g−1) of 0.6±0.3.
Landsat Images and Mosaics of Antarctica for Mapping and Glaciological Studies
Authors: Williams Richard S. , Ferrigno Jane G. , Kent Tina M. , Schoonmaker James W. 
Published: September 2017

The preparation of a US Geological Survey Professional Paper, “Satellite image atlas of glaciers”, has produced a 1:5 000 000 scale “Landsat index map of Antarctica”, in which each of the 2 470 Landsat nominal scene centers is represented by a symbol showing the suitability of available Landsat images for the preparation of planimetric image maps and for glaciological studies. Landsat has the potential for imaging about 79% of the area of Antarctica, and 70% of the Landsat imaging area, or about 55% of the continent, was found to have excellent or good (less than 10% cloud cover) coverage.Australia, Japan, New Zealand, the United Kingdom, and the United States of America have published Landsat image maps, either as single Landsat scenes or as mosaics of two or more images. The Federal Republic of Germany and the Republic of South Africa also plan to publish Landsat image maps in the near future.Available Landsat images could be used, in combination with Doppler satellite technology for geodetic control, to triple the area of Antarctica presently mapped at scales of 1:250 000 or larger. Landsat-3 RBV images can also be used to prepare 1:100 000 scale image maps.In addition to eventually using Landsat images to compile an accurate coastline of Antarctica, Landsat images have been successfully used for glaciological studies. Recent measurements of successive images of Pine Island Glacier, Walgreen Coast, West Antarctica, showed an average speed of flow of the terminus of 6 m d−1 over 750 d.
Structure Of The Energy Balance In The Ice Sheet-Atmosphere System As An Index Of Antarctic Glaciation (Abstract only)
Authors: Aver'yanov V. G. 
Published: September 2017

Various methods have been used to estimate mean multi-year values of moisture, radiation, and heat exchange in the Antarctic ice sheet/atmosphere system. The major components of the balance have been determined as absolute and relative values. The net advection of moisture is taken as 100%, of which 83% is deposited as accumulation on the ice sheet, and the residue in the atmosphere is 15%; loss from the icesheet surface is 2%. In the radiation balance, input at the top of the atmosphere is 57%, absorption in the atmosphere is 43%, loss due to reflected shortwave radiation is 35%, and long-wave radiation from the atmosphere is 78%, while net outgoing long-wave radiation from the surface is 9%. The heat-budget components are:
The Antarctic ice sheet is a vast heat sink. Constant negative surface-radiation balance and low temperature of the ice sheet suggests that it will survive with even small amounts of precipitation. Thus the contemporary glaciation of Antarctica is rather stable.
The East Antarctic Ice Sheet: The Problem of Palaeoglaciological Reconstruction (Abstract only)
Authors: Bardin V.I. 
Published: September 2017

Palaeoglaciological studies, including glaciogeomorphological observations and comprehensive studies of the composition of glacial deposits, undertaken by scientists of a number of countries, enable the major stages in the evolution of glaciation of some regions of East Antarctica to be outlined.In this report, palaeoglaciological reconstructions for certain key territories: Queen Maud Land, Mac. Robertson Land, and Victoria Land are considered. The completeness and reliability of such reconstructions are also discussed.The region of Prince Charles Mountains (Mac. Robertson Land) turned out to be one of the most significant for palaeoglaciology. In this region, the author has discovered and studied glacial deposits of at least six age stages, their formation having taken place during approximately 20 Ma.An attempt is made to compare the results of regional studies and to present the evolution of the development of the whole East Antarctic ice sheet in space and time.Different examples of palaeoglaciological reconstructions of the ice sheet of East Antarctica are presented, the possibilities of different approaches are evaluated practically, and schematic maps of the change in glaciation of East Antarctic regions at different evolutional stages, compiled by the author, are presented for discussion.
The Vertical Structure of the Antarctic Ice Sheet and Palaeoclimatic Interpretation of the Data (Abstract only)
Authors: Korotkevich Ye. , Petrov V.N. , Barkov N.I. , Lipenkov V.Ya. 
Published: September 2017

The ice core from the 1 415 m Vostok bore hole has been studied. It was found that the ice-grain size increases with depth in the upper 700 m, a sharp gradient change occurring in the 300 to 400 m range. The grain cross-section area at depths of 100, 200, 300, 400, 500, 600, and 700 m was 1.1, 2.0, 1.5, 1.9, 2.6, and 3.3 mm2 respectively. Since grain size is a function of age, and is determined by initial size and growth rate, the latter being exponentially related to ice temperature, an attempt was made to interpret the obtained data in terms of palaeoclimatology.Calculations show that the upper part of the ice sheet (down to 300 m depth) formed during the past 12 ka, and grew under temperatures higher than those at which the lower part of the ice formed, that is ice at 300 to 700 m depth. This conclusion was confirmed by the results of oxygen isotope analysis.The air content of ice at depths 100 to 650, 650 to 850, 850 to 1 100, and 1 100 to 1 400 m reduced to normal conditions was 65, 70, 75, and 70 mm3 g−1 respectively. Calculations suggest that 3 to 30 ka BP the ice-sheet elevation at Vostok station was close to the present one, while 30 to 40, 40 to 55, and 55 to 75 ka BP it was 500, 1 000, and 500 m lower than at present, respectively.
Control Exerted by Sea-Ice Extent Over Oxygen Isotope Ratios In Coastal Antarctic Precipitation (Abstract only)
Authors: Weaver Clark , Bromwich David H. 
Published: September 2017

The observations of the stable oxygen isotope composition δ of precipitation at the coastal Syowa station for 1974, which are reported and analyzed by Kato (1977, 1978), are reassessed on a monthly time scale. The relationship between oxygen isotope ratio and temperature is examined in detail. The mean temperature of the preceding month, rather than the temperature at the time of sample collection, has the best association with monthly averaged δ. This one-month lagged relationship suggests the strong influence of sea ice which is related to the average temperature in the same fashion. Linear regression analyses, using monthly variations of Antarctic seaice extent for 1974, as reported by Zwally and others (1979), reveal the following interrelationships which provide good support for the contention that sea-ice extent is a dominant factor for δ values in coastal Antarctic precipitation: For August 1974 the δ values are persistently less than those predicted by sea-ice area. Over the Southern Ocean, the zonal circulation in August was weak in comparison to the 1972–79 average. It is hypothesized that this anomalous circulation resulted in the source region of moisture precipitated at Syowa being located substantially farther north.This paper will be published in full elsewhere.
Trident: A Universal Tool for Generating Synthetic Absorption Spectra from Astrophysical Simulations
Authors: Hummels Cameron B. , Smith Britton D. , Silvia Devin W. 
Published: September 2017

Abstract
Hydrodynamical simulations are increasingly able to accurately model physical systems on stellar, galactic, and cosmological scales; however, the utility of these simulations is often limited by our ability to directly compare them with the data sets produced by observers: spectra, photometry, etc. To address this problem, we have created trident, a Python-based open-source tool for post-processing hydrodynamical simulations to produce synthetic absorption spectra and related data. trident can (i) create absorption-line spectra for any trajectory through a simulated data set mimicking both background quasar and down-the-barrel configurations; (ii) reproduce the spectral characteristics of common instruments like the Cosmic Origins Spectrograph; (iii) operate across the ultraviolet, optical, and infrared using customizable absorption-line lists; (iv) trace simulated physical structures directly to spectral features; (v) approximate the presence of ion species absent from the simulation outputs; (vi) generate column density maps for any ion; and (vii) provide support for all major astrophysical hydrodynamical codes. trident was originally developed to aid in the interpretation of observations of the circumgalactic medium and intergalactic medium, but it remains a general tool applicable in other contexts.
Pebble Accretion in Turbulent Protoplanetary Disks
Authors: Xu Ziyan , Bai Xue-Ning , Murray-Clay Ruth A. 
Published: September 2017

Abstract
It has been realized in recent years that the accretion of pebble-sized dust particles onto planetary cores is an important mode of core growth, which enables the formation of giant planets at large distances and assists planet formation in general. The pebble accretion theory is built upon the orbit theory of dust particles in a laminar protoplanetary disk (PPD). For sufficiently large core mass (in the “Hill regime”), essentially all particles of appropriate sizes entering the Hill sphere can be captured. However, the outer regions of PPDs are expected to be weakly turbulent due to the magnetorotational instability (MRI), where turbulent stirring of particle orbits may affect the efficiency of pebble accretion. We conduct shearing-box simulations of pebble accretion with different levels of MRI turbulence (strongly turbulent assuming ideal magnetohydrodynamics, weakly turbulent in the presence of ambipolar diffusion, and laminar) and different core masses to test the efficiency of pebble accretion at a microphysical level. We find that accretion remains efficient for marginally coupled particles (dimensionless stopping time

) even in the presence of strong MRI turbulence. Though more dust particles are brought toward the core by the turbulence, this effect is largely canceled by a reduction in accretion probability. As a result, the overall effect of turbulence on the accretion rate is mainly reflected in the changes in the thickness of the dust layer. On the other hand, we find that the efficiency of pebble accretion for strongly coupled particles (down to

) can be modestly reduced by strong turbulence for low-mass cores.
Model-independent Constraints on Cosmic Curvature and Opacity
Authors: Wang Guo-Jian , Wei Jun-Jie , Li Zheng-Xiang , Xia Jun-Qing , Zhu Zong-Hong 
Published: September 2017

Abstract
In this paper, we propose to estimate the spatial curvature of the universe and the cosmic opacity in a model-independent way with expansion rate measurements, H(z), and type Ia supernova (SNe Ia). On the one hand, using a nonparametric smoothing method Gaussian process, we reconstruct a function H(z) from opacity-free expansion rate measurements. Then, we integrate the H(z) to obtain distance modulus μ
H, which is dependent on the cosmic curvature. On the other hand, distances of SNe Ia can be determined by their photometric observations and thus are opacity-dependent. In our analysis, by confronting distance moduli μ
H with those obtained from SNe Ia, we achieve estimations for both the spatial curvature and the cosmic opacity without any assumptions for the cosmological model. Here, it should be noted that light curve fitting parameters, accounting for the distance estimation of SNe Ia, are determined in a global fit together with the cosmic opacity and spatial curvature to get rid of the dependence of these parameters on cosmology. In addition, we also investigate whether the inclusion of different priors for the present expansion rate (H
0: global estimation, 67.74 ± 0.46 km s−1 Mpc−1, and local measurement, 73.24 ± 1.74 km s−1 Mpc−1) exert influence on the reconstructed H(z) and the following estimations of the spatial curvature and cosmic opacity. Results show that, in general, a spatially flat and transparent universe is preferred by the observations. Moreover, it is suggested that priors for H
0 matter a lot. Finally, we find that there is a strong degeneracy between the curvature and the opacity.
Les activités sportives « hybrides » comme réponse à l’accélération des rythmes de vie
Authors: Quidu Matthieu 
Published: September 2017

Dans le monde contemporain, la majorité des acteurs sociaux fait quotidiennement l’expérience d’une accélération effrénée des rythmes de vie. Cette course contre la montre, qui tend à devenir chronique, semble affecter non seulement la sphère des obligations professionnelles et familiales mais aussi le champ des pratiques de loisirs. Dans un contexte de pénurie temporelle, où le temps est devenu une denrée aussi rare que précieuse, consentir d’y consacrer une partie à des activités non productives suppose de pouvoir obtenir un retour sur investissement. Quels types d’activités sportives peuvent satisfaire cette condition en permettant désormais aux pratiquants d’en avoir non seulement pour leur argent mais surtout pour leur temps ? À partir d’une étude de cas, la pratique d’un sport de combat de synthèse, le Mixed Martial Arts, par des étudiants de l’École Normale Supérieure de Lyon et anciens élèves des Classes Préparatoires aguerris à la gestion de l’urgence temporelle, nous montrerons que les activités sportives que nous qualifierons d’« hybrides » apparaissent, pour cette population, comme une réponse particulièrement pertinente au manque de temps en autorisant un engagement jugé rentable et efficient.
The relationship between lower limb muscle strength and lower extremity function in HIV disease
Authors: Mhariwa Peter C. , Myezwa Hellen , Galantino Mary L. , Maleka Douglas 
Published: September 2017

Background: Human immunodeficiency virus (HIV) negatively impacts muscle strength and function. This study aimed to establish the relationship between lower limb muscle strength and lower extremity function in HIV disease.Method: A cross-sectional study was undertaken with a sample of 113 HIV-positive participants. Lower limb muscle strength and self-reported function were established using dynamometry and the Lower Extremity Functional Scale (LEFS), respectively. Muscle strength and functional status were established in a subset of 30 HIV-negative participants to determine normative values.Results: Muscle strength for participants with HIV ranged from an ankle dorsiflexion mean of 9.33 kg/m2 to 15.79 kg/m2 in hip extensors. In the HIV-negative group, ankle dorsiflexors recorded 11.17 kg/m2, whereas hip extensors were the strongest, generating 17.68 kg/m2. In the HIV-positive group, linear regression showed a positive relationship between lower limb muscle strength and lower extremity function (r = 0.71, p = 0.00). Fifty per cent of the changes in lower extremity function were attributable to lower limb muscle strength. A simple linear regression model showed that lower limb ankle plantar flexors contributed the most to lower extremity function in this cohort, contrary to the literature which states that hip and trunk muscles are the most active in lower limb functional activities.Conclusion: Lower extremity strength impacts perceived function in individuals stabilised on antiretroviral therapy for HIV disease. These findings demonstrate that ankle plantar flexors produce more force over hip flexors. Careful attention should be paid to the implications for strength training in this population.