bluuebunny/crossref_metadata_2025 huggingface dataset:
Driving Stresses in the Antarctic Ice Sheet
Authors: Cooper A. P. R. , Mclntyre N. F. , Robin G. de Q.
Published: September 2017

Radio echo-soundings obtained during joint programmes of the US National Science Foundation (NSF), the Scott Polar Research Institute (SPRI), and the Technical University of Denmark (TUD) have provided sufficient data of good quality to map driving stress over approximately one half of the Antarctic ice sheet. Computerized averaging of data over 1 degree of latitude squares has largely eliminated local effects of longitudinal stress variations on surface slope. Methods of data handling are outlined. Variations in driving stresses between different regions are discussed in relation to the balancing restraining forces. These are primarily related to ice velocity and thickness, bedrock topography, the presence of basal water and possibly to the development of easy-glide fabric in the ice mass, to the temperature of basal ice layers, and to the excess hydrostatic pressure in areas where ice rests on bedrock well below sea-level.
Gas-Derived Aerosol in Central Antarctic Snow and Ice: the Case of Sulphuric and Nitric Acids
Authors: Delmas Robert J. , Barnola Jean Marc , Legrand Michel
Published: September 2017

New results concerning the concentration of sulphate (SO4) and nitrate (NO3) in Antarctic snow and ice are presented. At Dome C, 10-year mean values and detailed studies (more than one sample a−1) were done at different depths corresponding to ages from 0 to 23 ka BP. Global volcanic activity strongly disturbs profiles of sulphate concentration for periods of a few years. Long-term fluctuations are found to be weak for both anions. The mean values obtained for acidity agree satisfactorily with the values for sulphate and nitrate. Finally, we examine the probable origin of these gas-derived aerosols in Antarctica.
Physical and Structural Characteristics of Antarctic Sea Ice
Authors: Gow A.J. , Ackley S.F. , Weeks W.F. , Govoni J.W.
Published: September 2017

Observations during February and March 1980 of structures in 66 separate floes in Weddell Sea pack ice show widespread occurrence of frazil ice in amounts not previously reported in sea ice of comparable age and thickness in the Arctic. It is estimated that as much as 50% of the total ice production in the Weddell Sea is generated as frazil. Average floe salinities also appear higher than those of their Arctic counterparts. Comparative studies of fast ice at 28 locations in McMurdo Sound show this ice to be composed almost entirely of congelation ice that exhibits crystalline textures and orientations that are similar to those observed in Arctic fast ice. However, average fast-ice salinities in McMurdo Sound are higher than those reported for Arctic fast ice of comparable age and thickness.
Dynamics of Erebus Glacier Tongue
Authors: Holdsworth G.
Published: September 2017

Recent measurements conducted on Erebus Glacier Tongue (EGT) have enabled improvements to be made to previous analyses of earlier data (Holdsworth 1974). The use of LANDSAT imagery and controlled aerial photography up to 1978 have enabled glacier flow rates and hence strain-rates to be determined more accurately than before. Re-analysis of the stress and strain-rate data leads to flow law constants which are now more compatible with those of Thomas (1973). The thinner ice appears to be “softer” than the thicker ice. Bending of EGT appears to be the result of current pressure exerted on the south side of the glacier, and computed bending strains seem to account for most of the observed curvature of EGT.

Basal ice melting predominates over any possible refreezing; melt rates along the south edge exceed basal melt rates by a factor of 5-10. Short-period, pseudo-elastic deformations occurring in EGT as a result of ocean wave-induced motion may be responsible for continually activating crevasses and producing the apparent “softening” effect in the creep of the thinner ice. Such oscillations may also lead to the calving of EGT although recent observations suggest that a hinge-line calving due to horizontal bending of EGT may be just as likely.
On the Disintegration of Ice Shelves: the Role of Thinning
Authors: Hughes T. J.
Published: September 2017

It is proposed that an ice shelf disintegrates when its calving front retreats faster than its grounding line. This paper examines the role of ice thinning in grounding-line retreat. Thinning occurs as a result of creep spreading and ice melting. Thinning by creep is examined for the general regime of bending converging flow in an ice shelf lying in a confined embayment, and at the grounding lines of ice streams that supply the ice shelf and ice rises where the ice shelf is grounded on bedrock. Thinning by melting is examined at these grounding lines for tidal pumping and for descent of surface melt water into strandline crevasses, where concentrated melting is focused at the supposed weak links that connect the ice shelf to its embayment, its ice streams, and its ice rises. Applications are made to the Ross Ice Shelf.
Large-Scale Investigations of the Deformation Behaviour of Layers of Ice Shelves
Authors: Jessberger Hans L. , Dörr Rudolf
Published: September 2017

For the investigation of time-dependent vertical deformation of upper layers of ice shelves loaded by accumulated snow and/or structures a large-scale field test was started in 1980-81 at Georg von Neumayer station (70°37´S, 8°22´W), Antarctica. Specially developed base plugs were fixed to the bottoms of 5.0 and 10.0 m deep bore holes by melting and refreezing the surrounding firn. The deformations of the snow firn layers will be measured between these base plugs and metal plates placed on the snow surface during installation. The bore holes are kept open by tubes of different diameters in order to allow for load-induced vertical deformations of snow and firn. Some measurements are directly affected by the presence of the station. The design of the measuring device, the procedure of installation, and the measurement of deformation are described. The results of calculations of deformation and measurements of first settlement are presented.
The Brine Zone in the McMurdo Ice Shelf, Antarctica
Authors: Kovacs A. , Gow A. J. , Cragin J.
Published: September 2017

Infiltration of brine into the McMurdo Ice Shelf is dominated by wave-like intrusions of sea-water triggered by periodic break-outs of the ice front. Observations of a brine step 4.4 m in height in the McMurdo Ice Shelf show that it has migrated about 1.2 kin in four years. The present brine wave is overriding an older brine-soaked layer. This migration is proof of the dynamic nature of the step, which is the leading edge of a brine wave that originated at the ice front after a major break-out of the McMurdo Ice Shelf. The inland boundary of brine penetration is characterized by a series of descending steps that are believed to represent terminal positions of separate intrusions of brine of similar origin. The inland boundary of brine percolation is probably controlled largely by the depth at which brine encounters the firn/ice transition (43 m). However, this boundary is not fixed by permeability considerations alone, since measurable movement of brine is still occurring at the inland boundary. Freeze-fraction-ation of the sea-water as it migrates through the ice shelf precipitates virtually all sodium sulfate, and preferentially concomitant removal of water by freezing in the pore spaces of the infiltrated firn produces residual brines approximately seven times more concentrated than the original sea-water.
Atmospheric CO2 Content in the Past Deduced from Ice-Core Analyses
Authors: Oeschger H. , Stauffer B. , Neftel A. , Schwander J. , Zumbrunn R.
Published: September 2017

Probably the only direct way to reconstruct historic atmospheric CO2/air ratios is by measuring the air occluded in ice samples. For such studies, ice samples from very cold regions have an advantage in that the snow and ice probably never had been in contact with liquid water, which interacts with trapped atmospheric CO2. However, even ice samples from very cold regions may have additional CO2, which could have been enclosed during the formation of precipitation, adsorbed at the surface of snow and firn grains, or produced in the ice by chemical reactions on impurities. The gas in ice samples from Camp Cenand Byrd station was extracted both by a vacuum-melting and by a mechanical crushing procedure and the CO2 abundance measured by two different analytical methods. N2/O2/Ar ratios were also measured. The shift to lower CO2 concentration in both cores at a certain depth found previously is confirmed. Changes in the atmospheric CO2 concentration at the corresponding time, about the end of the last glaciation, is the probable explanation of our CO2 results.
Nitrate Fluctuations in Antarctic Snow and Firn: Potential Sources and Mechanisms of Formation
Authors: Parker Bruce C. , Zeller Edward J. , Gow Anthony J.
Published: September 2017

We summarize here data on in situ nitrate ion concentrations in snow pits and firn cores over the last ∼3 250 a. Nitrate fluctuations show seasonal, 11 and 22 a periodicities, and long-term changes both at South Pole station and Vostok. High nitrate levels conform to winter darkness and solar activity peaks. Long-term lows and highs conform to solar activity minima and maxima. The data available support the hypothesis that nitrate is fixed in the upper atmosphere by some solar-mediated phenomenon causing a periodicity in East Antarctica snow. Background levels and non-periodic spikes in nitrate come from other sources.
Analysis of A 870 M Deep Temperature Profile at Dome C
Authors: Ritz Catherine , Lliboutry Louis , Rado Claude
Published: September 2017

The French 870 m deep temperature profile gives us temperature differences with an accuracy of 0.01 deg (to obtain such an accuracy, the sensors must be applied against the walls of the bore hole). The error on the vertical gradient T' cannot be lessened by weighted running means. Thus, only a mean value of its derivative T" can be reached.

Data have been analysed by assuming a two-dimensional flow over a plane horizontal bedrock. As a first step, the steady state at an ice divide has been calculated by solving the complete set of equations. The vertical strain-rate is a constant over two-thirds of the ice sheet. It appears that, at Dome C, sliding and no-sliding solutions are plausible, as well as cyclic oscillations between them. Next, the temperature response of the ice sheet to an impulse for the surface temperature has been computed, and convolved with surface palaeotemperatures deduced from the 180 profile, to obtain the time derivative Ṫ.

Mean values of T', T" and Ṫ allow an estimation of the vertical velocity, which is much smaller than the balance one. Therefore, the ice sheet has thickened by 200 to 280 m during the last 10 ka.
Subglacial Water flow Under Ice Streams and West Antarctic Ice-Sheet Stability
Authors: Weertman J. , Birchfield G. E.
Published: September 2017

An analysis is made of the steady-state width of an ice sheet whose base is below sea-level, whose basal temperatures are such that appreciable melting occurs at the base, and which is fringed by fastmoving ice streams that drain most of the outward ice flux. The fast ice velocities of the ice streams are considered to be a consequence of substantial subglacial water flow underneath the ice streams. The source of this water is the water melted from the base of the ice sheet which is diverted to flow beneath the ice streams. If the depth of the sea at the edge of the ice sheet is not a function of the width of the ice sheet, then an ice sheet with a steady-state width is in a situation of unstable equilibrium. Only if the sea-level depth at the edge of the ice sheet increases as a function of ice-sheet width at a rate greater than the 2/3rd power of the width can a stable, steady-state ice sheet exist. This condition (taking into account elastic rebound) is not satisfied for the West Antarctic ice sheet along an ice-flow path from the ice divide above Byrd station out to the Ross Sea. An increase of the mean precipitation, such as might occur under a C02-induced climatic warming, would cause growth of both stable or unstable steady-state ice sheets.
The Radiation Budget At Mizuho Station, Antarctica, 1979
Authors: Yamanouchi Takashi , Wada Makoto , Mae Shinji , Kawaguchi Sadao , Kusunoki Kou
Published: September 2017

Radiation budget measurements were made at Mizuho station (70°42'S, 44"20'E, 2 230 m a. s.1.), East Antarctica, in 1979, within the framework of the Japanese POLEX-South programme. Global, and reflected short-wave and downward and upward long-wave radiat i on fluxes were measured at the snow surface and at the top of a 30 m tower. Direct solar radiation was also measured at the snow surface.

Seasonal variations of net radiation and net short-wave and net long-wave radiation are presented. Daily variation of net radiation is also presented with the daily value of meteorological elements. The monthly amounts of net radiation in winter months had very large negative values of about -80 MJ m−2 month−1. (-2 kly month−1). Daily totals of net radiation for clear skies were negative even i n summer, and were always smaller than those for cloudy skies. Monthly amounts of net radiation in summer months (about -1 MJ m−2 month−1 in December) were the smallest among the several Antarctic stations compared, and whether the balance was negative or positive depended on the ratio of clear and cloudy days. Comparison of seasonal variations of radiation components was made and the dominant cause of the radiation balance was discussed.
Field Studies of Bottom Crevasses in the Ross Ice Shelf, Antarctica (Abstract only)
Authors: Jezek Kenneth C. , Bentley Charles R.
Published: September 2017

Surface and airborne radar sounding data were used to identify and map fields of bottom crevasses on the Ross Ice Shelf. Two major concentrations of crevasses were found, one along the grid-eastern grounding line and another, made up of eight smaller sites, grid-west of Crary Ice Rise.

Based upon an analysis of bottom crevasse heights and locations, and of the strength of radar waves diffracted from the apex and bottom corners of the gridcrevasses, we conclude that the crevasses are formed at discrete locations on the ice shelf. By comparing the locations of crevasse formation with ice thickness and bottom topography, we conclude that most of the crevasse sites are associated with grounding. Hence we have postulated that six grounded areas, in addition to Crary Ice Rise and Roosevelt Island, exist in the grid-western sector of the ice shelf. These pinning points may be important for interpreting the dynamics of the West Antarctic ice sheet.
Absolute Movements, Mass Balance, and Snow Temperatures of the Riiser-Larsenisen (Abstract only)
Authors: Gjessing Yngvar , Wold Bjørn
Published: September 2017

During the Norwegian Antarctic Research Expeditions 1967–77 and 1978–79 a land party worked on Riiser-Larsenisen, an ice shelf 120 km wide on the coast of Dronning Maud Land (15° to 20°W). In February 1977 three patterns of six stakes each were laid out over areas of about 4 km2 as part of a combined investigation into absolute movements and strain-rates. Eight stakes for absolute movement were also laid out. The stakes were also used for determination of mean snow accumulation together with a stake line across the ice shelf. The positions of the stakes were determined by theodolite observations from the stake points and from trigonometric stations located on land and on an ice rise near the ice front.

In February 1979 all these measurements were repeated, and absolute movement, deformation, and mean accumulation were calculated. The absolute velocity of the ice shelf varied from 30 m a−1 near the grounding line to 130 m a−1 near the ice front. The mean annual accumulation was 510 mm water equivalent on the outer part of the ice shelf and 580 mm at the grounding line. Based on these measurements, together with snow-density measurements down to 16 m and measurements of the height of the ice shelf, the mass balance of the ice shelf was studied.

The stake pattern across the grounding line showed considerable expansion. This is interpreted as a result of water freezing in bottom crevasses made by the tides.

In 1979 snow temperatures were measured in eight bore holes down to 10 m depth. The snow temperatures at 10 m depth were used as a measure of the annual mean air temperature. The annual mean air temperature ranged from -16.8°C near the ice front to -19.2°C at the grounding line. Snow temperatures in bore holes on the slope of the ice rise and inland indicate a mean atmospheric temperature inversion of 0.28°C 100 m−1 for a 440 m layer near the grounding line, and 0.30°C 100 m−1 for a 160 m layer near the ice front. Here a mean inversion of 2.8°C 100 m−1 was found for the lowest 40 m layer of the atmosphere.
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 rises

This 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.
Description and Analysis of a 20-Year (1960-79) Digital Ice-Concentration Database for the Great Lakes of North America
Authors: Assel Raymond A.
Published: September 2017

A digital ice-concentration database spanning 20 years (1960 to 1979) was established for the Great Lakes of North America. Data on ice concentration, i.e. the percentage of a unit surface area of the lake that is ice-covered, were abstracted from over 2 800 historic ice charts produced by United States and Canadian government agencies. The database consists of ice concentrations ranging from zero to 100% in 10% increments for individual grid cells of size 5 × 5 km constituting the surface area of each Great Lake. The data set for each of the Great Lakes was divided into half-month periods for statistical analysis. Maxinium, minimum, median, mode, and average ice-concentrations statistics were calculated for each grid cell and half-month period. A lakewide average value was then calculated for each of the half-month ice-concentration statistics for all grid cells for a given lake. Ice-cover variability and the normal extent and progression of the ice cover is discussed within the context of the lakewide averaged value of the minimum and maximum ice concentrations and the lakewide averaged value of the median ice concentrations, respectively. Differences in ice-cover variability among the five Great Lakes are related to mean lake depth and accumulated freezing degree-days. A Great Lakes ice atlas presenting a series of ice charts which depict the maximum, minimum, and median icecover concentrations for each of the Great Lakes for nine half-monthly periods, starting the last half of December and continuing through the last half of April will be published in 1983 by the National Oceanic and Atmospheric Administration (NOAA). The database will be archived at the National Snow and Ice Data Center of the National Environmental Satellite Data and Information Service (NESDIS) in Boulder, Colorado, USA, also in 1983.
Icing Cloud Microstructure from in Situ Measurements
Authors: Gayet J. F. , Bain M.
Published: September 2017

In several experiments carried out in France, the Republic of the Ivory Coast, and Spain, icing clouds were penetrated at different heights by instrumented research aircraft. This paper describes the range and the frequencies of occurrence of the relevant icing parameters computed on the cloud scale and for different cloud types. Comparisons between micro-physical parameters and meteorolagical radar signatures show the limitations of these radars when used as a means of locating icing clouds.
Frequency and Characteristics of Glacier Floods in the Swiss Alps
Authors: Haeberli Wilfried
Published: September 2017

Damage due to glacier floods in the Swiss Alps occurs about once every two years at present, despite the pronounced retreat of glaciers during the twentieth century and the installation of many water reservoirs, which act as flood retention basins. Over half (60 to 70%) of the observed floods are caused by outbursts of marginal glacier lakes or sudden breaks of ice dams, and 30 to 40% by ruptures of water pockets. In a glacierized mountain region as densely populated as the Swiss Alps, even debris flows triggered by outbursts of very small water masses may be dangerous. Historical information about glacier floods in the Swiss Alps, although incomplete and heterogeneous, is used as an empirical basis for an attempt to recognize potential hazards at an early stage by considering outburst processes, volumes of water involved, potential peak-discharge values, lithology and inclination within the reach of glacier streams.
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.
On Forecasting Mesoscale Ice Dynamics and Build-Up
Authors: Hibler W. D. , Udin Ingemar , Ullerstig Anders
Published: September 2017

Due to the nonlinear nature of the ice interaction, sea-ice build-up against coasts and structures is a complex process. This build-up signifycantly affects mesoscale (10 to 100 km) ice motions over typical forecast time scales of several days. To examine the ramifications of assuming a non-linear ice interaction in ice forecast models, we have carried out a series of idealized simulations employing a viscous plastic sea-ice rheology (Hibler 1979). These simulations employ constant wind fields at a grid resolution of 18.5 km and allow the ice to build up and strengthen. With the plastic ice interaction the ice build-up is found to take place by means of a ridging front. Depending on the nature of the strength-thickness coupling, this build-up is accompanied by kinematic wave propagation effects. The nonlinear interaction can also result in fluctuating velocities in certain locations, even though the forcing is fixed. The build-up results are found to be consistent with the analytic solution of a one-dimensional rigid plastic model.
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.
Estimates of Ocean Currents Using a Labrador Sea Ice Model
Authors: Keliher T. E. , Foley J. S.
Published: September 2017

Efforts to develop a dynamical model of Labrador pack ice have been hampered by a lack of input data, especially ocean current data. This work reports the results of approaching this problem in another way, where model simulations are used as a basis for adjusting the input currents to obtain agreement with ice drift data. The ice drift data comes from a period in February 1977 when a ship was fast in the northern Labrador pack. Unfortunately, the ship experienced navigation problems and the direct current observations were suspect. The model simulations bear this out indicating that it would have been very unlikely that the observed currents along with the other forcing terms could lead to the observed ice drift. A climatological current data set gave better agreement and was slightly modified to give the best agreement. This improved data set was used for a short sensitivity test of the rheological specifications of the model. It was found that the ice drift tracks were not very sensitive to the linear viscous stress law but were more sensitive to the parameterization used to reduce ice velocities in areas of high ice concentration and fast ice. Further plans are to use a model with a more realistic rheological component in order to assess its importance in estimating currents.
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.
Snow and Slush on Floating Lake Ice
Authors: Röthlisberger Hans.
Published: September 2017

The behaviour of a floating sheet of lake ice was investigated for the case when it becomes loaded by a layer of fresh snow which is later soaked with water. This latter condition interferes with the traditional horse races of St Moritz, which are held on the lake each year. A piezometric precision gauge which measures accurately the vertical movements of the floating ice relative to the free surface of the lake is described. The level of the lake, in turn, oscillates, depending on the use of water by the local power company. Detailed measurements from the winter of 1978-79 are presented, showing that the piezometric level rises in direct response to precipitation, and that it rises further when the snow becomes soaked with water. With a simple model it is shown that the ultimate level is a function of the snow density, and it is concluded that immediate compaction of falling snow is an appropriate measure to reduce the amount of water entering the snow. It is very unlikely that the oscillations of the level of the lake caused by the demands of the power company have an influence on the slush problem.
An Elasticity Solution for Vibration Analysis of Laminated Plates with Functionally Graded Core Reinforced by Multi-walled Carbon Nanotubes
Authors: Tahouneh Vahid
Published: September 2017

In the present work, vibration characteristics of functionally graded (FG) sandwich rectangular plates reinforced by multiwalled carbon nanotubes (MWCNTs) resting on Pasternak foundation are presented. The response of the elastic medium is formulated by the Winkler/Pasternak model. Modified Halpin-Tsai equation is used to evaluate the Young’s modulus of the MWCNT/epoxy composite samples by the incorporation of an orientation as well as an exponential shape factor in the equation. The mass density and Poisson’s ratio of the MWCNT/phenolic composite are considered based on the rule of mixtures. The proposed sandwich rectangular plates have two opposite edges simply supported, while all possible combinations of free, simply supported and clamped boundary conditions are applied to the other two edges. The effects of two-parameter elastic foundation modulus, geometrical and material parameters together with the boundary conditions on the frequency parameters of the sandwich plates are investigated.
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.
Phytochemical composition of Anastatica hierochuntica L., can it fight the toxigenic bacterial agents responsible for food poisoning?
Authors: Benyagoub Elhassan , Razni Dalila , Moghtet Snoussi
Published: September 2017

The present work aims to study the biological activity of Anastatica hierochuntica L., against four bacterial strains considered as toxigenic responsible for food-borne infection. The plant was collected from Tindouf region (Far Southwest of Algeria). In this study we performed a phytochemical screening and evaluation of antibacterial activity of three macerates of two vegetative parts (seeds and stems) by two methods (disk and wells diffusion method). The yield of aqueous, methanolic and etheric macerates of the seeds and stems were (5.1; 3.8), (5; 1.4) and (2; 0.95)% respectively. Also, it appears that macerates obtained were rich in bioactive phyto-constituents particularly the seed of the plant. They showed the presence of ten large chemical groups. The antibiotic resistance profile of the bacterial strains tested showed an increased resistance to several families of antibiotics. The evaluation of the antibacterial activity of the extracts showed that methanolic and aqueous macerates of the seed were more active against Gram positive bacteria. The methanolic macerate of the stems was less active. However, other macerates were ineffective. The results obtained show that the plant has an average antibacterial activity and that depends on extract concentration used.Microbes and Health, June 2017, 6(1): 5-8
Variability of Precipitation in Arid Climates Using the Wavelet Approach: Case Study of Watershed of Gabes in South-East Tunisia
Authors: Jemai Sabrine , Ellouze Manel , Abida Habib
Published: September 2017

This study examines the variability of precipitation in the south-east of Tunisia through the analysis of data about annual and monthly precipitation at five stations in the Watershed of Gabes, from 1977 to 2015. Standardized precipitation ratio, wavelet and coherence wavelet analyses were applied to examine the temporal variability of monthly and annual precipitation and to determine the effect of climatic fluctuations on rainfall variability. Results of wavelet analysis showed varied energy bands at the studied stations at annual and inter-annual scales. The depicted bands spread according to intervals of 1-, 2- to 4-, 4- to 8- and 8- to 12-year cycles, obviously influenced by regional factors including altitude, proximity to the Mediterranean Sea and global fluctuations. Eventually, an analysis of wavelet coherence showed a strong correlation between precipitation and Mediterranean Oscillation (MO) in Gabes Watershed at different temporal scales. Contribution of the MO ranged between 51% and 93% of fluctuations (8–12 years) in the different examined rainfall stations.
The Madden-Julian Oscillation: A Tool for Regional Seasonal Precipitation Outlooks?
Authors: Curtis Scott
Published: September 2017

The Madden-Julian Oscillation (MJO) is an important intraseasonal climate signal which circles the global tropics, but also impacts extratropical weather regimes. Few studies have investigated whether the MJO is a source of regional seasonal climate predictability. The present objective is to determine the extent to which the season and phase (geographic location) of MJO contribute to the frequency of global rainfall anomalies in ensuing seasons. Indices of June-July-August and December-January-February MJO activity for each phase and the El Niño/Southern Oscillation (ENSO) were correlated to three-month averages of rainfall up to a six-month lead time. Field significance was calculated and patterns of the relationships were described. In general, MJO shows some skill in regional seasonal precipitation prediction, but to a lesser extent than ENSO. However, the presence of MJO in the western Indian Ocean and near the date line did reveal a persistent and significant relationship with regional seasonal rainfall, especially over Northern Hemisphere land areas.
Orness For Idempotent Aggregation Functions
Authors: Legarreta Leire , Lizasoain Inmaculada , Mardones-Pérez Iraide
Published: September 2017

Aggregation functions are mathematical operators that merge given data in order to obtain a global value that preserves the information given by the data as much as possible. In most practical applications, this value is expected to be between the infimum and the supremum of the given data, which is guaranteed only when the aggregation functions are idempotent. Ordered weighted averaging (OWA) operators are particular cases of this kind of function, with the particularity that the obtained global value depends on neither the source nor the expert that provides each datum, but only on the set of values. They have been classified by means of the orness—a measurement of the proximity of an OWA operator to the OR-operator. In this paper, the concept of orness is extended to the framework of idempotent aggregation functions defined both on the real unit interval and on a complete lattice with a local finiteness condition.
Nonequilibrium Phenomena in Confined Systems
Authors: Franzese Giancarlo , Latella Ivan , Rubi J.
Published: September 2017

Confined systems exhibit a large variety of nonequilibrium phenomena. In this special issue, we have collected a limited number of papers that were presented during the XXV Sitges Conference on Statistical Mechanics, devoted to “Nonequilibrium phenomena in confined systems”.[...]
Zebrafish in Translational Cancer Research: Insight into Leukemia, Melanoma, Glioma and Endocrine Tumor Biology
Authors: Idilli Aurora , Precazzini Francesca , Mione Maria , Anelli Viviana
Published: September 2017

Over the past 15 years, zebrafish have emerged as a powerful tool for studying human cancers. Transgenic techniques have been employed to model different types of tumors, including leukemia, melanoma, glioblastoma and endocrine tumors. These models present histopathological and molecular conservation with their human cancer counterparts and have been fundamental for understanding mechanisms of tumor initiation and progression. Moreover, xenotransplantation of human cancer cells in embryos or adult zebrafish offers the advantage of studying the behavior of human cancer cells in a live organism. Chemical-genetic screens using zebrafish embryos have uncovered novel druggable pathways and new therapeutic strategies, some of which are now tested in clinical trials. In this review, we will report on recent advances in using zebrafish as a model in cancer studies—with specific focus on four cancer types—where zebrafish has contributed to novel discoveries or approaches to novel therapies.
Timeliness of Childhood Primary Immunization and Risk Factors Related with Delays: Evidence from the 2014 Zhejiang Provincial Vaccination Coverage Survey
Authors: Hu Yu , Li Qian , Chen Yaping
Published: September 2017

Background: this study aimed to assess both immunization coverage and timeliness, as well as reasons for non-vaccination, and identity the risk factors of delayed immunization, for the vaccines scheduled during the first year of life, in Zhejiang province, east China. Methods: A cluster survey among children aged 24–35 months was conducted. Demographic information and socio-economic characteristics of the selected child, the mother, and the household were collected. Immunization data were transcribed from immunization cards. Timeliness was assessed with Kaplan–Meier analysis for each vaccine given before 12 months of age, based on the time frame stipulated by the expanded program on immunization of China. Cox proportional hazard regression was applied to identify risk factors of delayed immunization. Results: A total of 2772 eligible children were surveyed. The age-appropriate coverage ranged from 25.4% (95% CI: 23.7–27.0%) for Bacillus Calmette–Guerin (BCG) to 91.3% (95% CI: 90.2–92.3%) for the first dose of oral poliomyelitis vaccine (OPV1). The most frequent reason for non-vaccination was parent’s fear of adverse events of immunization. Delayed immunizations were associated with mother having a lower education level, mother having a job, delivery at home, increasing number of children per household, and having a lower household income. Conclusions: Although the timeliness of immunization has improved since 2011, necessary steps are still needed to achieve further improvement. Timeliness of immunization should be considered as another important indicator of expanded program on immunization (EPI) performance. Future interventions on vaccination coverage should take into consideration demographic and socio-economic risk factors identified in this study. The importance of adhering to the recommended schedule should be explained to parents.
To Wnt or Lose: The Missing Non-Coding Linc in Colorectal Cancer
Authors: Shen Peng , Pichler Martin , Chen Meng , Calin George , Ling Hui
Published: September 2017

Colorectal cancer (CRC) is the third most frequent cancer and one of the leading causes for cancer-related mortality. Aberrant activation of the Wnt signaling is an essential initiating factor in colon carcinogenesis, and a driving force of CRC progression. Recently, long non-coding RNAs (lncRNAs) have emerged as significant players in CRC pathogenesis through diversified mechanisms. Although both Wnt signaling and lncRNAs represent interesting research areas for CRC, an effort of directly connecting these two areas is lacking. To fill in the knowledge gap, we focus on the reported findings of lncRNAs that regulate Wnt signaling or essential Wnt signaling targets. These include several newly discovered lncRNAs originated from the amplified cancer-associated chromosome 8q24 region that surrounds the essential Wnt target MYC gene, lncRNAs reported to be involved in CRC stem cells, and several individual lncRNAs connected to Wnt signaling through other mechanisms. This review will provide essential information that assists in understanding the missing link of lncRNAs to the classical Wnt signaling in CRC.