WorldWideScience

Sample records for total ice volume

  1. 3D Volume and Morphology of Perennial Cave Ice and Related Geomorphological Models at Scăriloara Ice Cave, Romania, from Structure from Motion, Ground Penetrating Radar and Total Station Surveys

    Science.gov (United States)

    Hubbard, J.; Onac, B. P.; Kruse, S.; Forray, F. L.

    2017-12-01

    Research at Scăriloara Ice Cave has proceeded for over 150 years, primarily driven by the presence and paleoclimatic importance of the large perennial ice block and various ice speleothems located within its galleries. Previous observations of the ice block led to rudimentary volume estimates of 70,000 to 120,000 cubic meters (m3), prospectively placing it as one of the world's largest cave ice deposits. The cave morphology and the surface of the ice block are now recreated in a total station survey-validated 3D model, produced using Structure from Motion (SfM) software. With the total station survey and the novel use of ArcGIS tools, the SfM validation process is drastically simplified to produce a scaled, georeferenced, and photo-texturized 3D model of the cave environment with a root-mean-square error (RMSE) of 0.24 m. Furthermore, ground penetrating radar data was collected and spatially oriented with the total station survey to recreate the ice block basal surface and was combined with the SfM model to create a model of the ice block itself. The resulting ice block model has a volume of over 118,000 m3 with an uncertainty of 9.5%, with additional volumes left un-surveyed. The varying elevation of the ice block basal surface model reflect specific features of the cave roof, such as areas of enlargement, shafts, and potential joints, which offer further validation and inform theories on cave and ice genesis. Specifically, a large depression area was identified as a potential area of initial ice growth. Finally, an ice thickness map was produced that will aid in the designing of future ice coring projects. This methodology presents a powerful means to observe and accurately characterize and measure cave and cave ice morphologies with ease and affordability. Results further establish the significance of Scăriloara's ice block to paleoclimate research, provide insights into cave and ice block genesis, and aid future study design.

  2. Total volume versus bouts

    DEFF Research Database (Denmark)

    Chinapaw, Mai; Klakk, Heidi; Møller, Niels Christian

    2018-01-01

    BACKGROUND/OBJECTIVES: Examine the prospective relationship of total volume versus bouts of sedentary behaviour (SB) and moderate-to-vigorous physical activity (MVPA) with cardiometabolic risk in children. In addition, the moderating effects of weight status and MVPA were explored. SUBJECTS....../METHODS: Longitudinal study including 454 primary school children (mean age 10.3 years). Total volume and bouts (i.e. ≥10 min consecutive minutes) of MVPA and SB were assessed by accelerometry in Nov 2009/Jan 2010 (T1) and Aug/Oct 2010 (T2). Triglycerides, total cholesterol/HDL cholesterol ratio (TC:HDLC ratio......, with or without mutual adjustments between MVPA and SB. The moderating effects of weight status and MVPA (for SB only) were examined by adding interaction terms. RESULTS: Children engaged daily in about 60 min of total MVPA and 0-15 min/week in MVPA bouts. Mean total sedentary time was around 7 h/day with over 3...

  3. Ice thickness measurements and volume estimates for glaciers in Norway

    Science.gov (United States)

    Andreassen, Liss M.; Huss, Matthias; Melvold, Kjetil; Elvehøy, Hallgeir; Winsvold, Solveig H.

    2014-05-01

    Whereas glacier areas in many mountain regions around the world now are well surveyed using optical satellite sensors and available in digital inventories, measurements of ice thickness are sparse in comparison and a global dataset does not exist. Since the 1980s ice thickness measurements have been carried out by ground penetrating radar on many glaciers in Norway, often as part of contract work for hydropower companies with the aim to calculate hydrological divides of ice caps. Measurements have been conducted on numerous glaciers, covering the largest ice caps as well as a few smaller mountain glaciers. However, so far no ice volume estimate for Norway has been derived from these measurements. Here, we give an overview of ice thickness measurements in Norway, and use a distributed model to interpolate and extrapolate the data to provide an ice volume estimate of all glaciers in Norway. We also compare the results to various volume-area/thickness-scaling approaches using values from the literature as well as scaling constants we obtained from ice thickness measurements in Norway. Glacier outlines from a Landsat-derived inventory from 1999-2006 together with a national digital elevation model were used as input data for the ice volume calculations. The inventory covers all glaciers in mainland Norway and consists of 2534 glaciers (3143 glacier units) covering an area of 2692 km2 ± 81 km2. To calculate the ice thickness distribution of glaciers in Norway we used a distributed model which estimates surface mass balance distribution, calculates the volumetric balance flux and converts it into thickness using the flow law for ice. We calibrated this model with ice thickness data for Norway, mainly by adjusting the mass balance gradient. Model results generally agree well with the measured values, however, larger deviations were found for some glaciers. The total ice volume of Norway was estimated to be 275 km3 ± 30 km3. From the ice thickness data set we selected

  4. Distributed ice thickness and glacier volume in southern South America

    Science.gov (United States)

    Carrivick, Jonathan L.; Davies, Bethan J.; James, William H. M.; Quincey, Duncan J.; Glasser, Neil F.

    2016-11-01

    South American glaciers, including those in Patagonia, presently contribute the largest amount of meltwater to sea level rise per unit glacier area in the world. Yet understanding of the mechanisms behind the associated glacier mass balance changes remains unquantified partly because models are hindered by a lack of knowledge of subglacial topography. This study applied a perfect-plasticity model along glacier centre-lines to derive a first-order estimate of ice thickness and then interpolated these thickness estimates across glacier areas. This produced the first complete coverage of distributed ice thickness, bed topography and volume for 617 glaciers between 41°S and 55°S and in 24 major glacier regions. Maximum modelled ice thicknesses reach 1631 m ± 179 m in the South Patagonian Icefield (SPI), 1315 m ± 145 m in the North Patagonian Icefield (NPI) and 936 m ± 103 m in Cordillera Darwin. The total modelled volume of ice is 1234.6 km3 ± 246.8 km3 for the NPI, 4326.6 km3 ± 865.2 km3 for the SPI and 151.9 km3 ± 30.38 km3 for Cordillera Darwin. The total volume was modelled to be 5955 km3 ± 1191 km3, which equates to 5458.3 Gt ± 1091.6 Gt ice and to 15.08 mm ± 3.01 mm sea level equivalent (SLE). However, a total area of 655 km2 contains ice below sea level and there are 282 individual overdeepenings with a mean depth of 38 m and a total volume if filled with water to the brim of 102 km3. Adjusting the potential SLE for the ice volume below sea level and for the maximum potential storage of meltwater in these overdeepenings produces a maximum potential sea level rise (SLR) of 14.71 mm ± 2.94 mm. We provide a calculation of the present ice volume per major river catchment and we discuss likely changes to southern South America glaciers in the future. The ice thickness and subglacial topography modelled by this study will facilitate future studies of ice dynamics and glacier isostatic adjustment, and will be important for projecting water resources and

  5. Aircraft Icing Handbook. Volume 1

    Science.gov (United States)

    1991-03-01

    Maryland - . . . Kohiman Aviation, Lawrence , Kansas Ohio State University, Columbus, Ohio .I --- t-r 1-- - -t I.Q,,- t ../e . Pratt and Whitney...lower; about six percent at -22 ’F (-30 *C). 1.2.3 Variations with Season The summer or warm season months create large warm air masses which can...on Aircraft Surfaces," NASA TM 87184, May 1986. 2-54 Hausman , R.J. and Turnock, S.R., "Investigation of Surface Water Behavior During Glaze Ice

  6. A glimpse beneath Antarctic sea ice: observation of platelet-layer thickness and ice-volume fraction with multifrequency EM

    Science.gov (United States)

    Hoppmann, Mario; Hunkeler, Priska A.; Hendricks, Stefan; Kalscheuer, Thomas; Gerdes, Rüdiger

    2016-04-01

    In Antarctica, ice crystals (platelets) form and grow in supercooled waters below ice shelves. These platelets rise, accumulate beneath nearby sea ice, and subsequently form a several meter thick, porous sub-ice platelet layer. This special ice type is a unique habitat, influences sea-ice mass and energy balance, and its volume can be interpreted as an indicator of the health of an ice shelf. Although progress has been made in determining and understanding its spatio-temporal variability based on point measurements, an investigation of this phenomenon on a larger scale remains a challenge due to logistical constraints and a lack of suitable methodology. In the present study, we applied a lateral constrained Marquardt-Levenberg inversion to a unique multi-frequency electromagnetic (EM) induction sounding dataset obtained on the ice-shelf influenced fast-ice regime of Atka Bay, eastern Weddell Sea. We adapted the inversion algorithm to incorporate a sensor specific signal bias, and confirmed the reliability of the algorithm by performing a sensitivity study using synthetic data. We inverted the field data for sea-ice and platelet-layer thickness and electrical conductivity, and calculated ice-volume fractions within the platelet layer using Archie's Law. The thickness results agreed well with drillhole validation datasets within the uncertainty range, and the ice-volume fraction yielded results comparable to other studies. Both parameters together enable an estimation of the total ice volume within the platelet layer, which was found to be comparable to the volume of landfast sea ice in this region, and corresponded to more than a quarter of the annual basal melt volume of the nearby Ekström Ice Shelf. Our findings show that multi-frequency EM induction sounding is a suitable approach to efficiently map sea-ice and platelet-layer properties, with important implications for research into ocean/ice-shelf/sea-ice interactions. However, a successful application of this

  7. Ice volume distribution and implications on runoff projections in a glacierized catchment

    Directory of Open Access Journals (Sweden)

    J. Gabbi

    2012-12-01

    Full Text Available A dense network of helicopter-based ground-penetrating radar (GPR measurements was used to determine the ice-thickness distribution in the Mauvoisin region. The comprehensive set of ice-thickness measurements was combined with an ice-thickness estimation approach for an accurate determination of the bedrock. A total ice volume of 3.69 ± 0.31 km3 and a maximum ice thickness of 290 m were found. The ice-thickness values were then employed as input for a combined glacio-hydrological model forced by most recent regional climate scenarios. This model provided glacier evolution and runoff projections for the period 2010–2100. Runoff projections of the measured initial ice volume distribution show an increase in annual runoff of 4% in the next two decades, followed by a persistent runoff decrease until 2100. Finally, we checked the influence of the ice-thickness distribution on runoff projections. Our analyses revealed that reliable estimates of the ice volume are essential for modelling future glacier and runoff evolution. Wrong estimations of the total ice volume might even lead to deviations of the predicted general runoff trend.

  8. An estimate of the glacier ice volume in the Swiss Alps

    Science.gov (United States)

    Farinotti, Daniel; Huss, Matthias; Bauder, Andreas; Funk, Martin

    2009-08-01

    Changes in glacier volume are important for questions linked to sea-level rise, water resource management, and tourism industry. With the ongoing climate warming, the retreat of mountain glaciers is a major concern. Predictions of glacier changes, necessarily need the present ice volume as initial condition, and for transient modelling, the ice thickness distribution has to be known. In this paper, a method based on mass conservation and principles of ice flow dynamics is applied to 62 glaciers located in the Swiss Alps for estimating their ice thickness distribution. All available direct ice thickness measurements are integrated. The ice volumes are referenced to the year 1999 by means of a mass balance time series. The results are used to calibrate a volume-area scaling relation, and the coefficients obtained show good agreement with values reported in the literature. We estimate the total ice volume present in the Swiss Alps in the year 1999 to be 74 ± 9 km 3. About 12% of this volume was lost between 1999 and 2008, whereas the extraordinarily warm summer 2003 caused a volume loss of about 3.5%.

  9. Influence of temperature fluctuations on equilibrium ice sheet volume

    Science.gov (United States)

    Bøgeholm Mikkelsen, Troels; Grinsted, Aslak; Ditlevsen, Peter

    2018-01-01

    Forecasting the future sea level relies on accurate modeling of the response of the Greenland and Antarctic ice sheets to changing temperatures. The surface mass balance (SMB) of the Greenland Ice Sheet (GrIS) has a nonlinear response to warming. Cold and warm anomalies of equal size do not cancel out and it is therefore important to consider the effect of interannual fluctuations in temperature. We find that the steady-state volume of an ice sheet is biased toward larger size if interannual temperature fluctuations are not taken into account in numerical modeling of the ice sheet. We illustrate this in a simple ice sheet model and find that the equilibrium ice volume is approximately 1 m SLE (meters sea level equivalent) smaller when the simple model is forced with fluctuating temperatures as opposed to a stable climate. It is therefore important to consider the effect of interannual temperature fluctuations when designing long experiments such as paleo-spin-ups. We show how the magnitude of the potential bias can be quantified statistically. For recent simulations of the Greenland Ice Sheet, we estimate the bias to be 30 Gt yr-1 (24-59 Gt yr-1, 95 % credibility) for a warming of 3 °C above preindustrial values, or 13 % (10-25, 95 % credibility) of the present-day rate of ice loss. Models of the Greenland Ice Sheet show a collapse threshold beyond which the ice sheet becomes unsustainable. The proximity of the threshold will be underestimated if temperature fluctuations are not taken into account. We estimate the bias to be 0.12 °C (0.10-0.18 °C, 95 % credibility) for a recent estimate of the threshold. In light of our findings it is important to gauge the extent to which this increased variability will influence the mass balance of the ice sheets.

  10. Improved retrieval of land ice topography from CryoSat-2 data and its impact for volume-change estimation of the Greenland Ice Sheet

    DEFF Research Database (Denmark)

    Nilsson, Johan; Gardner, Alex; Sørensen, Louise Sandberg

    2016-01-01

    of the snow/ice surface with lower sensitivity to changes in near-surface dielectric properties. To demonstrate the utility of the new processing methodology we produce elevations, elevation changes, and total volume changes from CryoSat-2 data for the Greenland Ice Sheet during the period January 2011...... to January 2015. We find that the Greenland Ice Sheet decreased in volume at a rate of 289 ± 20km3 a-1, with high interannual variability and spatial heterogeneity in rates of loss. This rate is 65km3 a-1 more negative than rates determined from ESA's L2 product, highlighting the importance of CryoSat-2...

  11. Ice thickness, volume and subglacial topography of Urumqi Glacier ...

    Indian Academy of Sciences (India)

    4 m. 3 in 1981, 2001 and 2006, respectively. It has decreased by 21.2% during the past 25 years, which is .... all cases, a velocity of 169 m µs ... of ice volume calculation using this method is quite ..... industry, and agriculture in Xinjiang Uygur.

  12. Influence of temperature fluctuations on equilibrium ice sheet volume

    Directory of Open Access Journals (Sweden)

    T. B. Mikkelsen

    2018-01-01

    Full Text Available Forecasting the future sea level relies on accurate modeling of the response of the Greenland and Antarctic ice sheets to changing temperatures. The surface mass balance (SMB of the Greenland Ice Sheet (GrIS has a nonlinear response to warming. Cold and warm anomalies of equal size do not cancel out and it is therefore important to consider the effect of interannual fluctuations in temperature. We find that the steady-state volume of an ice sheet is biased toward larger size if interannual temperature fluctuations are not taken into account in numerical modeling of the ice sheet. We illustrate this in a simple ice sheet model and find that the equilibrium ice volume is approximately 1 m SLE (meters sea level equivalent smaller when the simple model is forced with fluctuating temperatures as opposed to a stable climate. It is therefore important to consider the effect of interannual temperature fluctuations when designing long experiments such as paleo-spin-ups. We show how the magnitude of the potential bias can be quantified statistically. For recent simulations of the Greenland Ice Sheet, we estimate the bias to be 30 Gt yr−1 (24–59 Gt yr−1, 95 % credibility for a warming of 3 °C above preindustrial values, or 13 % (10–25, 95 % credibility of the present-day rate of ice loss. Models of the Greenland Ice Sheet show a collapse threshold beyond which the ice sheet becomes unsustainable. The proximity of the threshold will be underestimated if temperature fluctuations are not taken into account. We estimate the bias to be 0.12 °C (0.10–0.18 °C, 95 % credibility for a recent estimate of the threshold. In light of our findings it is important to gauge the extent to which this increased variability will influence the mass balance of the ice sheets.

  13. Observations of Recent Arctic Sea Ice Volume Loss and Its Impact on Ocean-Atmosphere Energy Exchange and Ice Production

    Science.gov (United States)

    Kurtz, N. T.; Markus, T.; Farrell, S. L.; Worthen, D. L.; Boisvert, L. N.

    2011-01-01

    Using recently developed techniques we estimate snow and sea ice thickness distributions for the Arctic basin through the combination of freeboard data from the Ice, Cloud, and land Elevation Satellite (ICESat) and a snow depth model. These data are used with meteorological data and a thermodynamic sea ice model to calculate ocean-atmosphere heat exchange and ice volume production during the 2003-2008 fall and winter seasons. The calculated heat fluxes and ice growth rates are in agreement with previous observations over multiyear ice. In this study, we calculate heat fluxes and ice growth rates for the full distribution of ice thicknesses covering the Arctic basin and determine the impact of ice thickness change on the calculated values. Thinning of the sea ice is observed which greatly increases the 2005-2007 fall period ocean-atmosphere heat fluxes compared to those observed in 2003. Although there was also a decline in sea ice thickness for the winter periods, the winter time heat flux was found to be less impacted by the observed changes in ice thickness. A large increase in the net Arctic ocean-atmosphere heat output is also observed in the fall periods due to changes in the areal coverage of sea ice. The anomalously low sea ice coverage in 2007 led to a net ocean-atmosphere heat output approximately 3 times greater than was observed in previous years and suggests that sea ice losses are now playing a role in increasing surface air temperatures in the Arctic.

  14. Improving volume loss estimates of the northwestern Greenland Ice Sheet 2002-2010

    DEFF Research Database (Denmark)

    Korsgaard, Niels Jákup; Khan, Shfaqat Abbas; Kjeldsen, Kristian Kjellerup

    Studies have been carried out using various methods to estimate the Greenland ice sheet mass balance. Remote sensing techniques used to determine the ice sheet volume includes airborne and satellite radar and laser methods and measurements of ice flow of outlet glaciers use InSAR satellite radar......) does not work on sloping surfaces and is affected by radar penetration into the snow. InSAR estimates require knowledge of outlet glacier thickness. GRACE has limited spatial resolution and is affected by mass variations not just from ice changes, but also from hydrologic and ocean mass variability...... and mass redistribution within the solid Earth. The accuracy of ice mass and ice volume estimates can be assessed by comparing results from different techniques. Here, we focus on volume loss estimates from ICESat, ATM and LVIS data. We estimate catchment-wide ice volume change in northwest Greenland...

  15. HCCR TBS LOCA and ICE into small confined volume

    International Nuclear Information System (INIS)

    Jin, Hyung Gon; Ahn, Mu-Young

    2016-01-01

    KAERI has participated in the development of HCCR (Helium Cooled Ceramic Reflector) TBS (Test Blanket System) as a member of the KO TBM Team. Conceptual design review of this system had been performed in 2015 and after resolving the chits, the final approval was achieved in March 2016. This safety issue is one of the category II chits in the CDR and resolution strategy was already approved, however, safety analysis should be done until PDR (Preliminary Design Review). In this paper, model and nodalization for the accident are given and preliminary result is included. Nominal design pressure of HCS loop is 8 MPa, therefore, as indicated in the figure below. During the break of cooling pipe between TBM and Shield, the high pressure coolant will ingress to the 'interspace' between TBM, Shield and Frame. The coolant will be released through the front gaps between TBM and Frame towards VV primary vacuum. Accident analysis about HCCR TBS LOCA and ICE into small confined volume has been done successfully. Inverspace volume is compatibly small volume for 8MPa helium loop rupture, which causes fast pressure build-up the space but it decrease within 10 seconds. It is expected that other type of TBM has almost the same behavior

  16. Ice forces on marine structures. Volume 2, discussion

    Energy Technology Data Exchange (ETDEWEB)

    Marcellus, R W; Morrison, T B; Allyn, N F.B.; Croasdale, K R; Iyer, H S; Tseng, J

    1988-01-01

    A comprehensive state-of-the-art review is provided of the current methodologies in use for estimating the impact of ice forces on various kinds of marine structures: vertical sided or sloping stationary structures, floating structures, and artificial islands. Introductory chapters present ice statistics from selected Canadian marine regions, the failure modes and mechanical properties of ice, and general principles of ice/structure interactions. The methods for calculating ice loads are basically alternative methods for predicting the behavior of ice under different loading conditions; as such, none of the models have been successful in predicting the behavior of ice under all loading conditions. Currently the only reliable method for accurately predicting ice forces on marine structures is to use large-scale empirical data for ice of the same state as that predicted for design. Extrapolation from ice behavioral data at a smaller scale or ice of a different state is generally required. In comparison to current uncertainties, reasonably accurate estimates of upper bound static ice forces can be made, and a design approach using this upper bound force is appropriate for very massive rigid structures and in designing for overall global stability. The periodicity of ice forces also needs to be considered in terms of dynamic amplification of structure deformation, potential liquefaction of soils, and fatigue life. In certain cases, the deflection of the structure can change the ice failure process and therefore change the level and nature of the ice force. 221 refs., 171 figs., 19 tabs.

  17. Total tree, merchantable stem and branch volume models for ...

    African Journals Online (AJOL)

    Total tree, merchantable stem and branch volume models for miombo woodlands of Malawi. Daud J Kachamba, Tron Eid. Abstract. The objective of this study was to develop general (multispecies) models for prediction of total tree, merchantable stem and branch volume including options with diameter at breast height (dbh) ...

  18. Estimating the rates of mass change, ice volume change and snow volume change in Greenland from ICESat and GRACE data

    NARCIS (Netherlands)

    Slobbe, D.C.; Ditmar, P.G.; Lindenbergh, R.C.

    2008-01-01

    The focus of this paper is on the quantification of ongoing mass and volume changes over the Greenland ice sheet. For that purpose, we used elevation changes derived from the Ice, Cloud, and land Elevation Satellite (ICESat) laser altimetry mission and monthly variations of the Earth’s gravity field

  19. Vestibular schwannomas: Accuracy of tumor volume estimated by ice cream cone formula using thin-sliced MR images.

    Science.gov (United States)

    Ho, Hsing-Hao; Li, Ya-Hui; Lee, Jih-Chin; Wang, Chih-Wei; Yu, Yi-Lin; Hueng, Dueng-Yuan; Ma, Hsin-I; Hsu, Hsian-He; Juan, Chun-Jung

    2018-01-01

    We estimated the volume of vestibular schwannomas by an ice cream cone formula using thin-sliced magnetic resonance images (MRI) and compared the estimation accuracy among different estimating formulas and between different models. The study was approved by a local institutional review board. A total of 100 patients with vestibular schwannomas examined by MRI between January 2011 and November 2015 were enrolled retrospectively. Informed consent was waived. Volumes of vestibular schwannomas were estimated by cuboidal, ellipsoidal, and spherical formulas based on a one-component model, and cuboidal, ellipsoidal, Linskey's, and ice cream cone formulas based on a two-component model. The estimated volumes were compared to the volumes measured by planimetry. Intraobserver reproducibility and interobserver agreement was tested. Estimation error, including absolute percentage error (APE) and percentage error (PE), was calculated. Statistical analysis included intraclass correlation coefficient (ICC), linear regression analysis, one-way analysis of variance, and paired t-tests with P ice cream cone method, and ellipsoidal and Linskey's formulas significantly reduced the APE to 11.0%, 10.1%, and 12.5%, respectively (all P ice cream cone method and other two-component formulas including the ellipsoidal and Linskey's formulas allow for estimation of vestibular schwannoma volume more accurately than all one-component formulas.

  20. Ice volume and climate changes from a 6000 year sea-level record in French Polynesia.

    Science.gov (United States)

    Hallmann, N; Camoin, G; Eisenhauer, A; Botella, A; Milne, G A; Vella, C; Samankassou, E; Pothin, V; Dussouillez, P; Fleury, J; Fietzke, J

    2018-01-18

    Mid- to late-Holocene sea-level records from low-latitude regions serve as an important baseline of natural variability in sea level and global ice volume prior to the Anthropocene. Here, we reconstruct a high-resolution sea-level curve encompassing the last 6000 years based on a comprehensive study of coral microatolls, which are sensitive low-tide recorders. Our curve is based on microatolls from several islands in a single region and comprises a total of 82 sea-level index points. Assuming thermosteric contributions are negligible on millennial time scales, our results constrain global ice melting to be 1.5-2.5 m (sea-level equivalent) since ~5500 years before present. The reconstructed curve includes isolated rapid events of several decimetres within a few centuries, one of which is most likely related to loss from the Antarctic ice sheet mass around 5000 years before present. In contrast, the occurrence of large and flat microatolls indicates periods of significant sea-level stability lasting up to ~300 years.

  1. Trends in Arctic Sea Ice Volume 2010-2013 from CryoSat-2

    Science.gov (United States)

    Tilling, R.; Ridout, A.; Wingham, D.; Shepherd, A.; Haas, C.; Farrell, S. L.; Schweiger, A. J.; Zhang, J.; Giles, K.; Laxon, S.

    2013-12-01

    Satellite records show a decline in Arctic sea ice extent over the past three decades with a record minimum in September 2012, and results from the Pan-Arctic Ice-Ocean Modelling and Assimilation System (PIOMAS) suggest that this has been accompanied by a reduction in volume. We use three years of measurements recorded by the European Space Agency CryoSat-2 (CS-2) mission, validated with in situ data, to generate estimates of seasonal variations and inter-annual trends in Arctic sea ice volume between 2010 and 2013. The CS-2 estimates of sea ice thickness agree with in situ estimates derived from upward looking sonar measurements of ice draught and airborne measurements of ice thickness and freeboard to within 0.1 metres. Prior to the record minimum in summer 2012, autumn and winter Arctic sea ice volume had fallen by ~1300 km3 relative to the previous year. Using the full 3-year period of CS-2 observations, we estimate that winter Arctic sea ice volume has decreased by ~700 km3/yr since 2010, approximately twice the average rate since 1980 as predicted by the PIOMAS.

  2. A combined approach of remote sensing and airborne electromagnetics to determine the volume of polynya sea ice in the Laptev Sea

    Directory of Open Access Journals (Sweden)

    L. Rabenstein

    2013-06-01

    Full Text Available A combined interpretation of synthetic aperture radar (SAR satellite images and helicopter electromagnetic (HEM sea-ice thickness data has provided an estimate of sea-ice volume formed in Laptev Sea polynyas during the winter of 2007/08. The evolution of the surveyed sea-ice areas, which were formed between late December 2007 and middle April 2008, was tracked using a series of SAR images with a sampling interval of 2–3 days. Approximately 160 km of HEM data recorded in April 2008 provided sea-ice thicknesses along profiles that transected sea ice varying in age from 1 to 116 days. For the volume estimates, thickness information along the HEM profiles was extrapolated to zones of the same age. The error of areal mean thickness information was estimated to be between 0.2 m for younger ice and up to 1.55 m for older ice, with the primary error source being the spatially limited HEM coverage. Our results have demonstrated that the modal thicknesses and mean thicknesses of level ice correlated with the sea-ice age, but that varying dynamic and thermodynamic sea-ice growth conditions resulted in a rather heterogeneous sea-ice thickness distribution on scales of tens of kilometers. Taking all uncertainties into account, total sea-ice area and volume produced within the entire surveyed area were 52 650 km2 and 93.6 ± 26.6 km3. The surveyed polynya contributed 2.0 ± 0.5% of the sea-ice produced throughout the Arctic during the 2007/08 winter. The SAR-HEM volume estimate compares well with the 112 km3 ice production calculated with a~high-resolution ocean sea-ice model. Measured modal and mean-level ice thicknesses correlate with calculated freezing-degree-day thicknesses with a factor of 0.87–0.89, which was too low to justify the assumption of homogeneous thermodynamic growth conditions in the area, or indicates a strong dynamic thickening of level ice by rafting of even thicker ice.

  3. Effect Of Adding Sago Flour In Yoghurt Based On Viscosity, Overrun, Melting Rate And Total Solid Of Yoghurt Ice Cream

    Directory of Open Access Journals (Sweden)

    Ika Ayu Wijayanti

    2017-03-01

    Full Text Available The purpose of this research was to find out the best concentration of adding sago flour in yoghurt based on viscosity, overrun, melting rate and total solid of yoghurt ice cream. The experiment was designed by Completely Randomized Design (CRD using four treatments were 0 %, 2 %, 4 %, 6 % from volume of fresh milk and four replication. The data were analyzed by using Analysis of Variance (ANOVA and continued by Duncan’s Multiple Range Test (DMRT. Result of this research showed that concentration of adding sago flour in yoghurt gave highly significant difference effect (P<0.01 on viscosity, overrun, melting rate and total solid of yoghurt ice cream. It can be concluded that the adding of sago flour 2% in yoghurt gave the best result with the viscosity was 1750.75 cP, overrun was 25.14%, melting rate was 39.13 minutes/50 g, total solid was 36.20% and gave the best quality of yoghurt ice cream.

  4. Predicting uncertainty in future marine ice sheet volume using Bayesian statistical methods

    Science.gov (United States)

    Davis, A. D.

    2015-12-01

    The marine ice instability can trigger rapid retreat of marine ice streams. Recent observations suggest that marine ice systems in West Antarctica have begun retreating. However, unknown ice dynamics, computationally intensive mathematical models, and uncertain parameters in these models make predicting retreat rate and ice volume difficult. In this work, we fuse current observational data with ice stream/shelf models to develop probabilistic predictions of future grounded ice sheet volume. Given observational data (e.g., thickness, surface elevation, and velocity) and a forward model that relates uncertain parameters (e.g., basal friction and basal topography) to these observations, we use a Bayesian framework to define a posterior distribution over the parameters. A stochastic predictive model then propagates uncertainties in these parameters to uncertainty in a particular quantity of interest (QoI)---here, the volume of grounded ice at a specified future time. While the Bayesian approach can in principle characterize the posterior predictive distribution of the QoI, the computational cost of both the forward and predictive models makes this effort prohibitively expensive. To tackle this challenge, we introduce a new Markov chain Monte Carlo method that constructs convergent approximations of the QoI target density in an online fashion, yielding accurate characterizations of future ice sheet volume at significantly reduced computational cost.Our second goal is to attribute uncertainty in these Bayesian predictions to uncertainties in particular parameters. Doing so can help target data collection, for the purpose of constraining the parameters that contribute most strongly to uncertainty in the future volume of grounded ice. For instance, smaller uncertainties in parameters to which the QoI is highly sensitive may account for more variability in the prediction than larger uncertainties in parameters to which the QoI is less sensitive. We use global sensitivity

  5. Ice volume changes (1936–1990–2007 and ground-penetrating radar studies of Ariebreen, Hornsund, Spitsbergen

    Directory of Open Access Journals (Sweden)

    Javier Lapazaran

    2013-08-01

    Full Text Available Ariebreen is a small (0.37 km2-valley glacier located in southern Spitsbergen. Our ground-penetrating radar surveys of the glacier show that it is less than 30 m thick on average, with a maximum thickness of 82 m, and it appears to be entirely cold. By analysing digital terrain models of the ice surface from different dates, we determine the area and volume changes during two periods, 1936–1990 and 1990–2007. The total ice volume of the glacier has decreased by 73% during the entire period 1936–2007, which is equivalent to a mean mass balance rate of −0.61±0.17 m y−1 w.eq. The glacier thinning rate has increased markedly between the first and second periods, from −0.50±0.22 to −0.95±0.17 m y−1 w.eq.

  6. Southern Alaska Glaciers: Spatial and Temporal Variations in Ice Volume

    Science.gov (United States)

    Sauber, J.; Molnia, B. F.; Lutchke, S.; Rowlands, D.; Harding, D.; Carabajal, C.; Hurtado, J. M.; Spade, G.

    2004-01-01

    Although temperate mountain glaciers comprise less than 1% of the glacier-covered area on Earth, they are important because they appear to be melting rapidly under present climatic conditions and, therefore, make significant contributions to rising sea level. In this study, we use ICESat observations made in the last 1.5 years of southern Alaska glaciers to estimate ice elevation profiles, ice surface slopes and roughness, and bi-annual and/or annual ice elevation changes. We report initial results from the near coastal region between Yakutat Bay and Cape Suckling that includes the Malaspina and Bering Glaciers. We show and interpret ice elevations changes across the lower reaches of the Bagley Ice Valley for the period between October 2003 and May 2004. In addition, we use off-nadir pointing observations to reference tracks over the Bering and Malaspina Glaciers in order to estimate annual ice elevation change. Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and Shuttle Radar Topography Mission (SRTM) derived DEMs are used to estimate across track regional slopes between ICESat data acquisitions. Although the distribution and quantity of ICESat elevation profiles with multiple, exact repeat data is currently limited in Alaska, individual ICESat data tracks, provide an accurate reference surface for comparison to other elevation data (e.g. ASTER and SRTM X- and C-band derived DEMs). Specifically we report the elevation change over the Malaspina Glacier's piedmont lobe between a DEM derived from SRTM C-band data acquired in Feb. 2000 and ICESat Laser #2b data from Feb.-March 2004. We also report use of ICESat elevation data to enhance ASTER derived absolute DEMs. Mountain glaciers generally have rougher surfaces and steeper regional slopes than the ice sheets for which the ICESat design was optimized. Therefore, rather than averaging ICESat observations over large regions or relying on crossovers, we are working with well-located ICESat

  7. Atlas of total body radionuclide imaging. Volume I and II

    International Nuclear Information System (INIS)

    Fordham, E.W.; Ali, A.; Turner, D.A.; Charters, J.

    1982-01-01

    This two-volume work on total body imaging may well be regarded by future historians of nuclear medicine as representing the high points in the art of total body imaging in clinical nuclear medicine. With regard to information content and volume, it is the largest collection of well-interpreted, beautifully reproduced, total body images available to date. The primary goal of this atlas is to demonstrate patterns of abnormality in both typical and less typical variations. This goal is accomplished with many well-described examples of technical artifacts, of normal variants, of common and of rare diseases, and of pitfalls in interpretations. Volume I is entirely dedicated to skeletal imaging with Tc-99m labeled phosphates or phosphonates. The volume is divided into 22 chapters, which include chapters on methodology and instrumentation, chapters on the important bone diseases and other topics such as a treatise on false-negative and false-positive scans, and soft tissue and urinary tract abnormalities recognizable on bone scintigrams

  8. Bayesian prediction of future ice sheet volume using local approximation Markov chain Monte Carlo methods

    Science.gov (United States)

    Davis, A. D.; Heimbach, P.; Marzouk, Y.

    2017-12-01

    We develop a Bayesian inverse modeling framework for predicting future ice sheet volume with associated formal uncertainty estimates. Marine ice sheets are drained by fast-flowing ice streams, which we simulate using a flowline model. Flowline models depend on geometric parameters (e.g., basal topography), parameterized physical processes (e.g., calving laws and basal sliding), and climate parameters (e.g., surface mass balance), most of which are unknown or uncertain. Given observations of ice surface velocity and thickness, we define a Bayesian posterior distribution over static parameters, such as basal topography. We also define a parameterized distribution over variable parameters, such as future surface mass balance, which we assume are not informed by the data. Hyperparameters are used to represent climate change scenarios, and sampling their distributions mimics internal variation. For example, a warming climate corresponds to increasing mean surface mass balance but an individual sample may have periods of increasing or decreasing surface mass balance. We characterize the predictive distribution of ice volume by evaluating the flowline model given samples from the posterior distribution and the distribution over variable parameters. Finally, we determine the effect of climate change on future ice sheet volume by investigating how changing the hyperparameters affects the predictive distribution. We use state-of-the-art Bayesian computation to address computational feasibility. Characterizing the posterior distribution (using Markov chain Monte Carlo), sampling the full range of variable parameters and evaluating the predictive model is prohibitively expensive. Furthermore, the required resolution of the inferred basal topography may be very high, which is often challenging for sampling methods. Instead, we leverage regularity in the predictive distribution to build a computationally cheaper surrogate over the low dimensional quantity of interest (future ice

  9. A glimpse beneath Antarctic sea ice: observation of platelet-layer thickness and ice-volume fraction with multi-frequency EM

    Science.gov (United States)

    Hendricks, S.; Hoppmann, M.; Hunkeler, P. A.; Kalscheuer, T.; Gerdes, R.

    2015-12-01

    In Antarctica, ice crystals (platelets) form and grow in supercooled waters below ice shelves. These platelets rise and accumulate beneath nearby sea ice to form a several meter thick sub-ice platelet layer. This special ice type is a unique habitat, influences sea-ice mass and energy balance, and its volume can be interpreted as an indicator for ice - ocean interactions. Although progress has been made in determining and understanding its spatio-temporal variability based on point measurements, an investigation of this phenomenon on a larger scale remains a challenge due to logistical constraints and a lack of suitable methodology. In the present study, we applied a lateral constrained Marquardt-Levenberg inversion to a unique multi-frequency electromagnetic (EM) induction sounding dataset obtained on the ice-shelf influenced fast-ice regime of Atka Bay, eastern Weddell Sea. We adapted the inversion algorithm to incorporate a sensor specific signal bias, and confirmed the reliability of the algorithm by performing a sensitivity study using synthetic data. We inverted the field data for sea-ice and sub-ice platelet-layer thickness and electrical conductivity, and calculated ice-volume fractions from platelet-layer conductivities using Archie's Law. The thickness results agreed well with drill-hole validation datasets within the uncertainty range, and the ice-volume fraction also yielded plausible results. Our findings imply that multi-frequency EM induction sounding is a suitable approach to efficiently map sea-ice and platelet-layer properties. However, we emphasize that the successful application of this technique requires a break with traditional EM sensor calibration strategies due to the need of absolute calibration with respect to a physical forward model.

  10. Replicating the Ice-Volume Signal of the Early Pleistocene with a Complex Earth System Model

    Science.gov (United States)

    Tabor, C. R.; Poulsen, C. J.; Pollard, D.

    2013-12-01

    Milankovitch theory proposes high-latitude summer insolation intensity paces the ice ages by controlling perennial snow cover amounts (Milankovitch, 1941). According to theory, the ~21 kyr cycle of precession should dominate the ice-volume records since it has the greatest influence on high-latitude summer insolation. Modeling experiments frequently support Milankovitch theory by attributing the majority of Northern Hemisphere high-latitude summer snowmelt to changes in the cycle of precession (e.g. Jackson and Broccoli, 2003). However, ice-volume proxy records, especially those of the Early Pleistocene (2.6-0.8 Ma), display variability with a period of ~41 kyr (Raymo and Lisiecki, 2005), indicative of insolation forcing from obliquity, which has a much smaller influence on summer insolation intensity than precession. Several hypotheses attempt to explain the discrepancies between Milkankovitch theory and the proxy records by invoking phenomena such as insolation gradients (Raymo and Nisancioglu, 2003), hemispheric offset (Raymo et al., 2006; Lee and Poulsen, 2009), and integrated summer energy (Huybers, 2006); however, all of these hypotheses contain caveats (Ruddiman, 2006) and have yet to be supported by modeling studies that use a complex GCM. To explore potential solutions to this '41 kyr problem,' we use an Earth system model composed of the GENESIS GCM and Land Surface model, the BIOME4 vegetation model, and the Pennsylvania State ice-sheet model. Using an asynchronous coupling technique, we run four idealized transient combinations of obliquity and precession, representing the orbital extremes of the Pleistocene (Berger and Loutre, 1991). Each experiment is run through several complete orbital cycles with a dynamic ice domain spanning North America and Greenland, and fixed preindustrial greenhouse-gas concentrations. For all orbital configurations, model results produce greater ice-volume spectral power at the frequency of obliquity despite significantly

  11. Implications of changing scattering properties on Greenland ice sheet volume change from Cryosat-2 altimetry

    DEFF Research Database (Denmark)

    Simonsen, Sebastian Bjerregaard; Sørensen, Louise Sandberg

    2017-01-01

    ) in the elevation change algorithm, to correct for temporal changes in the ratio between surface- and volume-scatter in Cryosat-2 observations. We present elevation and volume changes for the Greenland ice sheet in the period from 2010 until 2014. The waveform parameters considered here are the backscatter...... waveform parameters to be applicable for correcting for changes in volume scattering. The best results in the Synthetic Aperture Radar Interferometric mode area of the GrIS are found when applying only the backscatter correction, whereas the best result in the Low Resolution Mode area is obtained by only......Long-term observations of surface elevation change of the Greenland ice sheet (GrIS) is of utmost importance when assessing the state of the ice sheet. Satellite radar altimetry offers a long time series of data over the GrIS, starting with ERS-1 in 1991. ESA's Cryosat-2 mission, launched in 2010...

  12. Modeling the imprint of Milankovitch cycles on early Pleistocene ice volume

    Science.gov (United States)

    Roychowdhury, R.; DeConto, R.; Pollard, D.

    2017-12-01

    Global climate during Quaternary and Late Pliocene (present-3.1 Ma) is characterized by alternating glacial and interglacial conditions. Several proposed theories associate these cycles with variations in the Earth's orbital configuration. In this study, we attempt to address the anomalously strong obliquity forcing in the Late Pliocene/Early Pleistocene ice volume records (41 kyr world), which stands in sharp contrast to the primary cyclicity of insolation, which is at precessional periods (23 kyr). Model results from GCM simulations show that at low eccentricities (e0.015), precessional response is important, and the insolation metrics vary out-of-phase between the two hemispheres. Using simulations from a GCM-driven ice sheet model, we simulate time continuous ice volume changes from Northern and Southern Hemispheres. Under eccentricities lower than 0.015, ice sheets in both hemispheres respond only to obliquity cycle, and grow and melt together (in-phase). If the ice sheet is simulated with eccentricity higher than 0.015, both hemispheres become more sensitive to precessional variation, and vary out-of-phase with each other, which is consistent with proxy observations from the late Pleistocene glaciations. We use the simulated ice volumes from 2.0 to 1.0 ma to empirically calculate global benthic δ18O variations based on the assumption that relationships between collapse and growth of ice-sheets and sea level is linear and symmetric and that the isotopic signature of the individual ice-sheets has not changed with time. Our modeled global benthic δ18O values are broadly consistent with the paleoclimate proxy records such as the LR04 stack.

  13. County-Level Climate Uncertainty for Risk Assessments: Volume 25 Appendix X - Forecast Sea Ice Age.

    Energy Technology Data Exchange (ETDEWEB)

    Backus, George A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lowry, Thomas Stephen [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Jones, Shannon M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Walker, La Tonya Nicole [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Roberts, Barry L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Malczynski, Leonard A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-05-01

    This report uses the CMIP5 series of climate model simulations to produce country- level uncertainty distributions for use in socioeconomic risk assessments of climate change impacts. It provides appropriate probability distributions, by month, for 169 countries and autonomous-areas on temperature, precipitation, maximum temperature, maximum wind speed, humidity, runoff, soil moisture and evaporation for the historical period (1976-2005), and for decadal time periods to 2100. It also provides historical and future distributions for the Arctic region on ice concentration, ice thickness, age of ice, and ice ridging in 15-degree longitude arc segments from the Arctic Circle to 80 degrees latitude, plus two polar semicircular regions from 80 to 90 degrees latitude. The uncertainty is meant to describe the lack of knowledge rather than imprecision in the physical simulation because the emphasis is on unfalsified risk and its use to determine potential socioeconomic impacts. The full report is contained in 27 volumes.

  14. County-Level Climate Uncertainty for Risk Assessments: Volume 23 Appendix V - Forecast Sea Ice Thickness

    Energy Technology Data Exchange (ETDEWEB)

    Backus, George A.; Lowry, Thomas Stephen; Jones, Shannon M; Walker, La Tonya Nicole; Roberts, Barry L; Malczynski, Leonard A.

    2017-04-01

    This report uses the CMIP5 series of climate model simulations to produce country- level uncertainty distributions for use in socioeconomic risk assessments of climate change impacts. It provides appropriate probability distributions, by month, for 169 countries and autonomous-areas on temperature, precipitation, maximum temperature, maximum wind speed, humidity, runoff, soil moisture and evaporation for the historical period (1976-2005), and for decadal time periods to 2100. It also provides historical and future distributions for the Arctic region on ice concentration, ice thickness, age of ice, and ice ridging in 15-degree longitude arc segments from the Arctic Circle to 80 degrees latitude, plus two polar semicircular regions from 80 to 90 degrees latitude. The uncertainty is meant to describe the lack of knowledge rather than imprecision in the physical simulation because the emphasis is on unfalsified risk and its use to determine potential socioeconomic impacts. The full report is contained in 27 volumes.

  15. County-Level Climate Uncertainty for Risk Assessments: Volume 24 Appendix W - Historical Sea Ice Age.

    Energy Technology Data Exchange (ETDEWEB)

    Backus, George A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lowry, Thomas Stephen [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Jones, Shannon M [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Walker, La Tonya Nicole [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Roberts, Barry L [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Malczynski, Leonard A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-05-01

    This report uses the CMIP5 series of climate model simulations to produce country- level uncertainty distributions for use in socioeconomic risk assessments of climate change impacts. It provides appropriate probability distributions, by month, for 169 countries and autonomous-areas on temperature, precipitation, maximum temperature, maximum wind speed, humidity, runoff, soil moisture and evaporation for the historical period (1976-2005), and for decadal time periods to 2100. It also provides historical and future distributions for the Arctic region on ice concentration, ice thickness, age of ice, and ice ridging in 15-degree longitude arc segments from the Arctic Circle to 80 degrees latitude, plus two polar semicircular regions from 80 to 90 degrees latitude. The uncertainty is meant to describe the lack of knowledge rather than imprecision in the physical simulation because the emphasis is on unfalsified risk and its use to determine potential socioeconomic impacts. The full report is contained in 27 volumes.

  16. County-Level Climate Uncertainty for Risk Assessments: Volume 22 Appendix U - Historical Sea Ice Thickness

    Energy Technology Data Exchange (ETDEWEB)

    Backus, George A.; Lowry, Thomas Stephen; Jones, Shannon M; Walker, La Tonya Nicole; Roberts, Barry L; Malczynski, Leonard A.

    2017-06-01

    This report uses the CMIP5 series of climate model simulations to produce country- level uncertainty distributions for use in socioeconomic risk assessments of climate change impacts. It provides appropriate probability distributions, by month, for 169 countries and autonomous-areas on temperature, precipitation, maximum temperature, maximum wind speed, humidity, runoff, soil moisture and evaporation for the historical period (1976-2005), and for decadal time periods to 2100. It also provides historical and future distributions for the Arctic region on ice concentration, ice thickness, age of ice, and ice ridging in 15-degree longitude arc segments from the Arctic Circle to 80 degrees latitude, plus two polar semicircular regions from 80 to 90 degrees latitude. The uncertainty is meant to describe the lack of knowledge rather than imprecision in the physical simulation because the emphasis is on unfalsified risk and its use to determine potential socioeconomic impacts. The full report is contained in 27 volumes.

  17. Clinical associations of total kidney volume: the Framingham Heart Study.

    Science.gov (United States)

    Roseman, Daniel A; Hwang, Shih-Jen; Oyama-Manabe, Noriko; Chuang, Michael L; O'Donnell, Christopher J; Manning, Warren J; Fox, Caroline S

    2017-08-01

    Total kidney volume (TKV) is an imaging biomarker that may have diagnostic and prognostic utility. The relationships between kidney volume, renal function and cardiovascular disease (CVD) have not been characterized in a large community-dwelling population. This information is needed to advance the clinical application of TKV. We measured TKV in 1852 Framingham Heart Study participants (mean age 64.1 ± 9.2 years, 53% women) using magnetic resonance imaging. A healthy sample was used to define reference values. The associations between TKV, renal function and CVD risk factors were determined using multivariable logistic regression analysis. Overall, mean TKV was 278 ± 54 cm3 for women and 365 ± 66 cm3 for men. Risk factors for high TKV (>90% healthy referent size) were body surface area (BSA), diabetes, smoking and albuminuria, while age, female and estimated glomerular filtration rate (eGFR) kidney damage including albuminuria and eGFR <60 mL/min/1.73 m2, while high TKV is associated with diabetes and decreased odds of eGFR <60 mL/min/1.73 m2. Prospective studies are needed to characterize the natural progression and clinical consequences of TKV. Published by Oxford University Press on behalf of ERA-EDTA 2016. This work is written by US Government employees and is in the public domain in the US.

  18. Ice Ih anomalies: Thermal contraction, anomalous volume isotope effect, and pressure-induced amorphization

    Science.gov (United States)

    Salim, Michael A.; Willow, Soohaeng Yoo; Hirata, So

    2016-05-01

    Ice Ih displays several anomalous thermodynamic properties such as thermal contraction at low temperatures, an anomalous volume isotope effect (VIE) rendering the volume of D2O ice greater than that of H2O ice, and a pressure-induced transition to the high-density amorphous (HDA) phase. Furthermore, the anomalous VIE increases with temperature, despite its quantum-mechanical origin. Here, embedded-fragment ab initio second-order many-body perturbation (MP2) theory in the quasiharmonic approximation (QHA) is applied to the Gibbs energy of an infinite, proton-disordered crystal of ice Ih at wide ranges of temperatures and pressures. The quantum effect of nuclei moving in anharmonic potentials is taken into account from first principles without any empirical or nonsystematic approximation to either the electronic or vibrational Hamiltonian. MP2 predicts quantitatively correctly the thermal contraction at low temperatures, which is confirmed to originate from the volume-contracting hydrogen-bond bending modes (acoustic phonons). It qualitatively reproduces (but underestimates) the thermal expansion at higher temperatures, caused by the volume-expanding hydrogen-bond stretching (and to a lesser extent librational) modes. The anomalous VIE is found to be the result of subtle cancellations among closely competing isotope effects on volume from all modes. Consequently, even ab initio MP2 with the aug-cc-pVDZ and aug-cc-pVTZ basis sets has difficulty reproducing this anomaly, yielding qualitatively varied predictions of the sign of the VIE depending on such computational details as the choice of the embedding field. However, the temperature growth of the anomalous VIE is reproduced robustly and is ascribed to the librational modes. These solid-state MP2 calculations, as well as MP2 Born-Oppenheimer molecular dynamics, find a volume collapse and a loss of symmetry and long-range order in ice Ih upon pressure loading of 2.35 GPa or higher. Concomitantly, rapid softening of

  19. Ice Ih anomalies: Thermal contraction, anomalous volume isotope effect, and pressure-induced amorphization

    Energy Technology Data Exchange (ETDEWEB)

    Salim, Michael A.; Willow, Soohaeng Yoo; Hirata, So, E-mail: sohirata@illinois.edu [Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801 (United States)

    2016-05-28

    Ice Ih displays several anomalous thermodynamic properties such as thermal contraction at low temperatures, an anomalous volume isotope effect (VIE) rendering the volume of D{sub 2}O ice greater than that of H{sub 2}O ice, and a pressure-induced transition to the high-density amorphous (HDA) phase. Furthermore, the anomalous VIE increases with temperature, despite its quantum-mechanical origin. Here, embedded-fragment ab initio second-order many-body perturbation (MP2) theory in the quasiharmonic approximation (QHA) is applied to the Gibbs energy of an infinite, proton-disordered crystal of ice Ih at wide ranges of temperatures and pressures. The quantum effect of nuclei moving in anharmonic potentials is taken into account from first principles without any empirical or nonsystematic approximation to either the electronic or vibrational Hamiltonian. MP2 predicts quantitatively correctly the thermal contraction at low temperatures, which is confirmed to originate from the volume-contracting hydrogen-bond bending modes (acoustic phonons). It qualitatively reproduces (but underestimates) the thermal expansion at higher temperatures, caused by the volume-expanding hydrogen-bond stretching (and to a lesser extent librational) modes. The anomalous VIE is found to be the result of subtle cancellations among closely competing isotope effects on volume from all modes. Consequently, even ab initio MP2 with the aug-cc-pVDZ and aug-cc-pVTZ basis sets has difficulty reproducing this anomaly, yielding qualitatively varied predictions of the sign of the VIE depending on such computational details as the choice of the embedding field. However, the temperature growth of the anomalous VIE is reproduced robustly and is ascribed to the librational modes. These solid-state MP2 calculations, as well as MP2 Born–Oppenheimer molecular dynamics, find a volume collapse and a loss of symmetry and long-range order in ice Ih upon pressure loading of 2.35 GPa or higher. Concomitantly, rapid

  20. Response of faults to climate-driven changes in ice and water volumes on Earth's surface.

    Science.gov (United States)

    Hampel, Andrea; Hetzel, Ralf; Maniatis, Georgios

    2010-05-28

    Numerical models including one or more faults in a rheologically stratified lithosphere show that climate-induced variations in ice and water volumes on Earth's surface considerably affect the slip evolution of both thrust and normal faults. In general, the slip rate and hence the seismicity of a fault decreases during loading and increases during unloading. Here, we present several case studies to show that a postglacial slip rate increase occurred on faults worldwide in regions where ice caps and lakes decayed at the end of the last glaciation. Of note is that the postglacial amplification of seismicity was not restricted to the areas beneath the large Laurentide and Fennoscandian ice sheets but also occurred in regions affected by smaller ice caps or lakes, e.g. the Basin-and-Range Province. Our results do not only have important consequences for the interpretation of palaeoseismological records from faults in these regions but also for the evaluation of the future seismicity in regions currently affected by deglaciation like Greenland and Antarctica: shrinkage of the modern ice sheets owing to global warming may ultimately lead to an increase in earthquake frequency in these regions.

  1. Sea level and global ice volumes from the Last Glacial Maximum to the Holocene.

    Science.gov (United States)

    Lambeck, Kurt; Rouby, Hélène; Purcell, Anthony; Sun, Yiying; Sambridge, Malcolm

    2014-10-28

    The major cause of sea-level change during ice ages is the exchange of water between ice and ocean and the planet's dynamic response to the changing surface load. Inversion of ∼1,000 observations for the past 35,000 y from localities far from former ice margins has provided new constraints on the fluctuation of ice volume in this interval. Key results are: (i) a rapid final fall in global sea level of ∼40 m in sea level, the main phase of deglaciation occurred from ∼16.5 ka BP to ∼8.2 ka BP at an average rate of rise of 12 m⋅ka(-1) punctuated by periods of greater, particularly at 14.5-14.0 ka BP at ≥40 mm⋅y(-1) (MWP-1A), and lesser, from 12.5 to 11.5 ka BP (Younger Dryas), rates; (iv) no evidence for a global MWP-1B event at ∼11.3 ka BP; and (v) a progressive decrease in the rate of rise from 8.2 ka to ∼2.5 ka BP, after which ocean volumes remained nearly constant until the renewed sea-level rise at 100-150 y ago, with no evidence of oscillations exceeding ∼15-20 cm in time intervals ≥200 y from 6 to 0.15 ka BP.

  2. Ice-volume-forced erosion of the Chinese Loess Plateau global Quaternary stratotype site

    DEFF Research Database (Denmark)

    Stevens, T.; Buylaert, J.-P.; Thiel, C.

    2018-01-01

    propose a new independent age model and reconstruct monsoon climate and desert expansion/contraction for the last similar to 250 ka. Our record demonstrates the dominant influence of ice volume on desert expansion, dust dynamics and sediment preservation, and further shows that East Asian Summer Monsoon...... chronology for the Quaternary terrestrial type section at Jingbian, desert marginal Chinese Loess Plateau, is inaccurate. There are large hiatuses and depositional changes expressed across a dynamic gully landform at the site, which demonstrates rapid environmental shifts at the East Asian desert margin. We...... (EASM) variation closely matches that of ice volume, but lags insolation by similar to 5 ka. These observations show that the EASM at the monsoon margin does not respond directly to precessional forcing....

  3. Quantifying volume loss from ice cliffs on debris-covered glaciers using high-resolution terrestrial and aerial photogrammetry

    NARCIS (Netherlands)

    Brun, Fanny; Buri, Pascal; Miles, Evan S.; Wagnon, Patrick; Steiner, J.F.; Berthier, Etienne; Ragettli, S.; Kraaijenbrink, P.D.A.; Immerzeel, W.W.; Pellicciotti, Francesca

    Mass losses originating from supraglacial ice cliffs at the lower tongues of debris-covered glaciers are a potentially large component of the mass balance, but have rarely been quantified. In this study, we develop a method to estimate ice cliff volume losses based on high-resolution topographic

  4. Ice formation via deposition nucleation on mineral dust and organics: dependence of onset relative humidity on total particulate surface area

    International Nuclear Information System (INIS)

    Kanji, Zamin A; Florea, Octavian; Abbatt, Jonathan P D

    2008-01-01

    We present ice nucleation results for Arizona test dust, kaolinite, montmorillonite, silica, silica coated with a hydrophobic octyl chain, oxalic acid dihydrate, Gascoyne leonardite (a humic material), and Aldrich humic acid (sodium salt). The focus was on deposition mode nucleation below water saturation at 233 K. Particles were deposited onto a hydrophobic cold stage by atomization of a slurry/solution and exposed to a constant partial pressure of water vapor. By lowering the temperature of the stage, the relative humidity with respect to ice (RH i ) was gradually increased until ice nucleation was observed using digital photography. Different numbers of particles were deposited onto the cold stage by varying the atomization solution concentration and deposition time. For the same total particulate surface area, mineral dust particles nucleated ice at lower supersaturations than all other materials. The most hydrophobic materials, i.e. Gascoyne leonardite and octyl silica, were the least active. For our limit of detection of one ice crystal, the ice onset RH i values were dependent on the total surface area of the particulates, indicating that no unique threshold RH i for ice nucleation prevails

  5. Ice formation via deposition nucleation on mineral dust and organics: dependence of onset relative humidity on total particulate surface area

    Energy Technology Data Exchange (ETDEWEB)

    Kanji, Zamin A; Florea, Octavian; Abbatt, Jonathan P D [Department of Chemistry, University of Toronto, 80 St George Street, Toronto, ON, M5S 3H6 (Canada)], E-mail: zkanji@chem.utoronto.ca

    2008-04-15

    We present ice nucleation results for Arizona test dust, kaolinite, montmorillonite, silica, silica coated with a hydrophobic octyl chain, oxalic acid dihydrate, Gascoyne leonardite (a humic material), and Aldrich humic acid (sodium salt). The focus was on deposition mode nucleation below water saturation at 233 K. Particles were deposited onto a hydrophobic cold stage by atomization of a slurry/solution and exposed to a constant partial pressure of water vapor. By lowering the temperature of the stage, the relative humidity with respect to ice (RH{sub i}) was gradually increased until ice nucleation was observed using digital photography. Different numbers of particles were deposited onto the cold stage by varying the atomization solution concentration and deposition time. For the same total particulate surface area, mineral dust particles nucleated ice at lower supersaturations than all other materials. The most hydrophobic materials, i.e. Gascoyne leonardite and octyl silica, were the least active. For our limit of detection of one ice crystal, the ice onset RH{sub i} values were dependent on the total surface area of the particulates, indicating that no unique threshold RH{sub i} for ice nucleation prevails.

  6. Global ice volume variations through the last glacial cycle simulated by a 3-D ice-dynamical model

    NARCIS (Netherlands)

    Bintanja, R.; Wal, R.S.W. van de; Oerlemans, J.

    2002-01-01

    A coupled ice sheet—ice shelf—bedrock model was run at 20km resolution to simulate the evolution of global ice cover during the last glacial cycle. The mass balance model uses monthly mean temperature and precipitation as input and incorporates the albedo—mass balance feedback. The model is forced

  7. Capillary ion chromatography with on-column focusing for ultra-trace analysis of methanesulfonate and inorganic anions in limited volume Antarctic ice core samples.

    Science.gov (United States)

    Rodriguez, Estrella Sanz; Poynter, Sam; Curran, Mark; Haddad, Paul R; Shellie, Robert A; Nesterenko, Pavel N; Paull, Brett

    2015-08-28

    Preservation of ionic species within Antarctic ice yields a unique proxy record of the Earth's climate history. Studies have been focused until now on two proxies: the ionic components of sea salt aerosol and methanesulfonic acid. Measurement of the all of the major ionic species in ice core samples is typically carried out by ion chromatography. Former methods, whilst providing suitable detection limits, have been based upon off-column preconcentration techniques, requiring larger sample volumes, with potential for sample contamination and/or carryover. Here, a new capillary ion chromatography based analytical method has been developed for quantitative analysis of limited volume Antarctic ice core samples. The developed analytical protocol applies capillary ion chromatography (with suppressed conductivity detection) and direct on-column sample injection and focusing, thus eliminating the requirement for off-column sample preconcentration. This limits the total sample volume needed to 300μL per analysis, allowing for triplicate sample analysis with Application to composite ice-core samples is demonstrated, with coupling of the capillary ion chromatograph to high resolution mass spectrometry used to confirm the presence and purity of the observed methanesulfonate peak. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Stereological quantification of tumor volume, mean nuclear volume and total number of melanoma cells correlated with morbidity and mortality

    DEFF Research Database (Denmark)

    Bønnelykke-Behrndtz, Marie Louise; Sørensen, Flemming Brandt; Damsgaard, Tine Engberg

    2008-01-01

    potential indicators of prognosis. Sixty patients who underwent surgery at the Department of Plastic Surgery, Aarhus University Hospital, from 1991 to 1994 were included in the study. Total tumor volume was estimated by the Cavalieri technique, total number of tumor cells by the optical dissector principle...... showed a significant impact on both disease-free survival (p=0.001) and mortality (p=0.009). In conclusion, tumor volume and total number of cancer cells were highly reproducible but did not add additional, independent prognostic information regarding the study population.......Stereological quantification of tumor volume, total number of tumor cells and mean nuclear volume provides unbiased data, regardless of the three-dimensional shape of the melanocytic lesion. The aim of the present study was to investigate whether these variables are reproducible and may represent...

  9. CryoSat-2 Processing and Model Interpretation of Greenland Ice Sheet Volume Changes

    Science.gov (United States)

    Nilsson, J.; Gardner, A. S.; Sandberg Sorensen, L.

    2015-12-01

    CryoSat-2 was launched in late 2010 tasked with monitoring the changes of the Earth's land and sea ice. It carries a novel radar altimeter allowing the satellite to monitor changes in highly complex terrain, such as smaller ice caps, glaciers and the marginal areas of the ice sheets. Here we present on the development and validation of an independent elevation retrieval processing chain and respective elevation changes based on ESA's L1B data. Overall we find large improvement in both accuracy and precision over Greenland relative to ESA's L2 product when comparing against both airborne data and crossover analysis. The seasonal component and spatial sampling of the surface elevation changes where also compared against ICESat derived changes from 2003-2009. The comparison showed good agreement between the to product on a local scale. However, a global sampling bias was detected in the seasonal signal due to the clustering of CryoSat-2 data in higher elevation areas. The retrieval processing chain presented here does not correct for changes in surface scattering conditions and appears to be insensitive to the 2012 melt event (Nilsson et al., 2015). This in contrast to the elevation changes derived from ESA's L2 elevation product, which where found to be sensitive to the effects of the melt event. The positive elevation bias created by the event introduced a discrepancy between the two products with a magnitude of roughly 90 km3/year. This difference can directly be attributed to the differences in retracking procedure pointing to the importance of the retracking of the radar waveforms for altimetric volume change studies. Greenland 2012 melt event effects on CryoSat-2 radar altimetry./ Nilsson, Johan; Vallelonga, Paul Travis; Simonsen, Sebastian Bjerregaard; Sørensen, Louise Sandberg; Forsberg, René; Dahl-Jensen, Dorthe; Hirabayashi, Motohiro; Goto-Azuma, Kumiko; Hvidberg, Christine S.; Kjær, Helle A.; Satow, Kazuhide.

  10. County-Level Climate Uncertainty for Risk Assessments: Volume 21 Appendix T - Forecast Sea Ice Area Fraction.

    Energy Technology Data Exchange (ETDEWEB)

    Backus, George A.; Lowry, Thomas Stephen; Jones, Shannon M; Walker, La Tonya Nicole; Roberts, Barry L; Malczynski, Leonard A.

    2017-06-01

    This report uses the CMIP5 series of climate model simulations to produce country- level uncertainty distributions for use in socioeconomic risk assessments of climate change impacts. It provides appropriate probability distributions, by month, for 169 countries and autonomous-areas on temperature, precipitation, maximum temperature, maximum wind speed, humidity, runoff, soil moisture and evaporation for the historical period (1976-2005), and for decadal time periods to 2100. It also provides historical and future distributions for the Arctic region on ice concentration, ice thickness, age of ice, and ice ridging in 15-degree longitude arc segments from the Arctic Circle to 80 degrees latitude, plus two polar semicircular regions from 80 to 90 degrees latitude. The uncertainty is meant to describe the lack of knowledge rather than imprecision in the physical simulation because the emphasis is on unfalsified risk and its use to determine potential socioeconomic impacts. The full report is contained in 27 volumes.

  11. County-Level Climate Uncertainty for Risk Assessments: Volume 20 Appendix S - Historical Sea Ice Area Fraction

    Energy Technology Data Exchange (ETDEWEB)

    Backus, George A.; Lowry, Thomas Stephen; Jones, Shannon M; Walker, La Tonya Nicole; Roberts, Barry L; Malczynski, Leonard A.

    2017-06-01

    This report uses the CMIP5 series of climate model simulations to produce country- level uncertainty distributions for use in socioeconomic risk assessments of climate change impacts. It provides appropriate probability distributions, by month, for 169 countries and autonomous-areas on temperature, precipitation, maximum temperature, maximum wind speed, humidity, runoff, soil moisture and evaporation for the historical period (1976-2005), and for decadal time periods to 2100. It also provides historical and future distributions for the Arctic region on ice concentration, ice thickness, age of ice, and ice ridging in 15-degree longitude arc segments from the Arctic Circle to 80 degrees latitude, plus two polar semicircular regions from 80 to 90 degrees latitude. The uncertainty is meant to describe the lack of knowledge rather than imprecision in the physical simulation because the emphasis is on unfalsified risk and its use to determine potential socioeconomic impacts. The full report is contained in 27 volumes.

  12. First in situ measurement of the vertical distribution of ice volume in a mesospheric ice cloud during the ECOMA/MASS rocket-campaign

    Energy Technology Data Exchange (ETDEWEB)

    Rapp, M.; Strelnikova, I.; Strelnikov, B. [Leibniz-Institute of Atmospheric Physics, Kuehlungsborn (DE)] (and others)

    2009-07-01

    We present in situ observations of mesospheric ice particles with a new particle detector which combines a classical Faraday cup with the active photoionization of particles and subsequent detection of photoelectrons. Our observations of charged particles and free electrons within a decaying PMSE-layer reveal that the presence of charged particles is a necessary but not sufficient condition for the presence of PMSE. That is, additional requirements like a sufficiently large electron density - which we here estimate to be on the order of {proportional_to}100 cm{sup -3} - and the presence of small scale structures (commonly assumed to be caused by turbulence) need to be satisfied. Our photoelectron measurements reveal a very strong horizontal structuring of the investigated ice layer, i.e., a very broad layer (82-88 km) seen on the upleg is replaced by a narrow layer from 84.5-86 km only 50 km apart on the downleg of the rocket flight. Importantly, the qualitative structure of these photoelectron profiles is in remarkable qualitative agreement with photometer measurements on the same rocket thus demonstrating the reliability of this new technique. We then show that the photoelectron currents are a unique function of the ice particle volume density (and hence ice mass) within an uncertainty of only 15% and we derive corresponding altitude profiles of ice volume densities. Derived values are in the range {proportional_to}2-8 x 10{sup -14} cm{sup 3}/cm{sup 3} (corresponding to mass densities of {proportional_to}20-80 ng/m{sup 3}, and water vapor mixing ratios of 3-12 ppm) and are the first such estimates with the unique spatial resolution of an in situ measurement. (orig.)

  13. First in situ measurement of the vertical distribution of ice volume in a mesospheric ice cloud during the ECOMA/MASS rocket-campaign

    Directory of Open Access Journals (Sweden)

    M. Rapp

    2009-02-01

    Full Text Available We present in situ observations of mesospheric ice particles with a new particle detector which combines a classical Faraday cup with the active photoionization of particles and subsequent detection of photoelectrons. Our observations of charged particles and free electrons within a decaying PMSE-layer reveal that the presence of charged particles is a necessary but not sufficient condition for the presence of PMSE. That is, additional requirements like a sufficiently large electron density – which we here estimate to be on the order of ~100 cm−3 – and the presence of small scale structures (commonly assumed to be caused by turbulence need to be satisfied. Our photoelectron measurements reveal a very strong horizontal structuring of the investigated ice layer, i.e., a very broad layer (82–88 km seen on the upleg is replaced by a narrow layer from 84.5–86 km only 50 km apart on the downleg of the rocket flight. Importantly, the qualitative structure of these photoelectron profiles is in remarkable qualitative agreement with photometer measurements on the same rocket thus demonstrating the reliability of this new technique. We then show that the photoelectron currents are a unique function of the ice particle volume density (and hence ice mass within an uncertainty of only 15% and we derive corresponding altitude profiles of ice volume densities. Derived values are in the range ~2–8×10−14 cm3/cm3 (corresponding to mass densities of ~20–80 ng/m3, and water vapor mixing ratios of 3–12 ppm and are the first such estimates with the unique spatial resolution of an in situ measurement.

  14. First in situ measurement of the vertical distribution of ice volume in a mesospheric ice cloud during the ECOMA/MASS rocket-campaign

    Directory of Open Access Journals (Sweden)

    M. Rapp

    2009-02-01

    Full Text Available We present in situ observations of mesospheric ice particles with a new particle detector which combines a classical Faraday cup with the active photoionization of particles and subsequent detection of photoelectrons. Our observations of charged particles and free electrons within a decaying PMSE-layer reveal that the presence of charged particles is a necessary but not sufficient condition for the presence of PMSE. That is, additional requirements like a sufficiently large electron density – which we here estimate to be on the order of ~100 cm−3 – and the presence of small scale structures (commonly assumed to be caused by turbulence need to be satisfied. Our photoelectron measurements reveal a very strong horizontal structuring of the investigated ice layer, i.e., a very broad layer (82–88 km seen on the upleg is replaced by a narrow layer from 84.5–86 km only 50 km apart on the downleg of the rocket flight. Importantly, the qualitative structure of these photoelectron profiles is in remarkable qualitative agreement with photometer measurements on the same rocket thus demonstrating the reliability of this new technique. We then show that the photoelectron currents are a unique function of the ice particle volume density (and hence ice mass within an uncertainty of only 15% and we derive corresponding altitude profiles of ice volume densities. Derived values are in the range ~2–8×10−14 cm3/cm3 (corresponding to mass densities of ~20–80 ng/m3, and water vapor mixing ratios of 3–12 ppm and are the first such estimates with the unique spatial resolution of an in situ measurement.

  15. Controls on Arctic sea ice from first-year and multi-year ice survival rates

    Science.gov (United States)

    Armour, K.; Bitz, C. M.; Hunke, E. C.; Thompson, L.

    2009-12-01

    The recent decrease in Arctic sea ice cover has transpired with a significant loss of multi-year (MY) ice. The transition to an Arctic that is populated by thinner first-year (FY) sea ice has important implications for future trends in area and volume. We develop a reduced model for Arctic sea ice with which we investigate how the survivability of FY and MY ice control various aspects of the sea-ice system. We demonstrate that Arctic sea-ice area and volume behave approximately as first-order autoregressive processes, which allows for a simple interpretation of September sea-ice in which its mean state, variability, and sensitivity to climate forcing can be described naturally in terms of the average survival rates of FY and MY ice. This model, used in concert with a sea-ice simulation that traces FY and MY ice areas to estimate the survival rates, reveals that small trends in the ice survival rates explain the decline in total Arctic ice area, and the relatively larger loss of MY ice area, over the period 1979-2006. Additionally, our model allows for a calculation of the persistence time scales of September area and volume anomalies. A relatively short memory time scale for ice area (~ 1 year) implies that Arctic ice area is nearly in equilibrium with long-term climate forcing at all times, and therefore observed trends in area are a clear indication of a changing climate. A longer memory time scale for ice volume (~ 5 years) suggests that volume can be out of equilibrium with climate forcing for long periods of time, and therefore trends in ice volume are difficult to distinguish from its natural variability. With our reduced model, we demonstrate the connection between memory time scale and sensitivity to climate forcing, and discuss the implications that a changing memory time scale has on the trajectory of ice area and volume in a warming climate. Our findings indicate that it is unlikely that a “tipping point” in September ice area and volume will be

  16. Relative blood volume changes underestimate total blood volume changes during hemodialysis

    NARCIS (Netherlands)

    Dasselaar, Judith J.; Lub-de Hooge, Marjolijn N.; Pruim, Jan; Nijnuis, Hugo; Wiersum, Anneke; de Jong, Paul E.; Huisman, Roel M.; Franssen, Casper F. M.

    Background: Measurements of relative blood volume changes (ARBV) during hemodialysis (HD) are based on hemoconcentration and assume uniform mixing of erythrocytes and plasma throughout the circulation. However, whole-body hematocrit (Ht) is lower than systemic Ht. During HD, a change in the ratio

  17. The impact of dynamic topography on the bedrock elevation and volume of the Pliocene Antarctic Ice Sheet

    Science.gov (United States)

    Austermann, Jacqueline; Pollard, David; Mitrovica, Jerry X.; Moucha, Robert; Forte, Alessandro M.; DeConto, Robert M.

    2015-04-01

    Reconstructions of the Antarctic ice sheet over long timescales (i.e. Myrs) require estimates of bedrock elevation through time. Ice sheet models have accounted, with varying levels of sophistication, for changes in the bedrock elevation due to glacial isostatic adjustment (GIA), but they have neglected other processes that may perturb topography. One notable example is dynamic topography, the deflection of the solid surface of the Earth due to convective flow within the mantle. Numerically predicted changes in dynamic topography have been used to correct paleo shorelines for this departure from eustasy, but the effect of such changes on ice sheet stability is unknown. In this study we use numerical predictions of time-varying dynamic topography to reconstruct bedrock elevation below the Antarctic ice sheet during the mid Pliocene warm period (~3 Ma). Moreover, we couple this reconstruction to a three-dimensional ice sheet model to explore the impact of dynamic topography on the evolution of the Antarctic ice sheet since the Pliocene. Our modeling indicates significant uplift in the area of the Transantarctic Mountains (TAM) and the adjacent Wilkes basin. This predicted uplift, which is at the lower end of geological inferences of uplift of the TAM, implies a lower elevation of the basin in the Pliocene. Relative to simulations that do not include dynamic topography, the lower elevation leads to a smaller Antarctic Ice Sheet volume and a more significant retreat of the grounding line in the Wilkes basin, both of which are consistent with offshore sediment core data. We conclude that reconstructions of the Antarctic Ice Sheet during the mid-Pliocene warm period should be based on bedrock elevation models that include the impact of both GIA and dynamic topography.

  18. The relationship of hospital charges and volume to surgical site infection after total hip replacement.

    Science.gov (United States)

    Boas, Rebecca; Ensor, Kelsey; Qian, Edward; Hutzler, Lorraine; Slover, James; Bosco, Joseph

    2015-05-01

    The purpose of this study was to analyze the effect of hospital volume and charges on the rate of surgical site infections for total hip replacements (THRs) in New York State (NYS). In NYS, higher volume hospitals have higher charges after THR. The study team analyzed 93,620 hip replacements performed in NYS between 2008 and 2011. Hospital charges increased significantly from $43,713 in 2008 to $50,652 in 2011 (P<.01). Compared with lower volume hospitals, patients who underwent THR at the highest volume hospitals had significantly lower surgical site infection rates (P=.003) and higher total hospital charges (P<.0001). The study team found that in the highest volume hospitals, preventing one surgical site infection was associated with $1.6 million dollars in increased charges. © 2014 by the American College of Medical Quality.

  19. The Effect of Structured Exercise Intervention on Intensity and Volume of Total Physical Activity

    Directory of Open Access Journals (Sweden)

    Niko Wasenius

    2014-12-01

    Full Text Available This study aimed to investigate the effects of a 12-week structured exercise intervention on total physical activity and its subcategories. Twenty-three overweight or obese middle aged men with impaired glucose regulation were randomized into a 12-week Nordic walking group, a power-type resistance training group, and a non-exercise control group. Physical activity was measured with questionnaires before the intervention (1–4 weeks and during the intervention (1–12 weeks and was expressed in metabolic equivalents of task. No significant change in the volume of total physical activity between or within the groups was observed (p > 0.050. The volume of total leisure-time physical activity (structured exercises + non-structured leisure-time physical activity increased significantly in the Nordic walking group (p 0.050 compared to the control group. In both exercise groups increase in the weekly volume of total leisure-time physical activity was inversely associated with the volume of non-leisure-time physical activities. In conclusion, structured exercise intervention did not increase the volume of total physical activity. Albeit, endurance training can increase the volume of high intensity physical activities, however it is associated with compensatory decrease in lower intensity physical activities. To achieve effective personalized exercise program, individuality in compensatory behavior should be recognised.

  20. Sea-ice monitoring by ship-based visual observation during JARE ―Simplification of observation method based on the ASPeCt protocol―

    OpenAIRE

    Kay I. Ohshima; Shuki Ushio; Akihisa S. Otsuki

    2006-01-01

    A protocol for ship-based visual observation of sea ice is proposed for the Japanese Antarctic Research Expedition (JARE). The protocol is a simplified version of the ASPeCt protocol, used for extracting quantitative information on sea ice. The ship-based visual observations started from JARE-46. In the pack ice region, ice thickness, ratio of deformed ice, and total ice volume increased toward the coast. Continuous monitoring of sea ice, particularly its thickness, by ship-based observation ...

  1. Developmentally Sensitive Interaction Effects of Genes and the Social Environment on Total and Subcortical Brain Volumes.

    Science.gov (United States)

    Richards, Jennifer S; Arias Vásquez, Alejandro; Franke, Barbara; Hoekstra, Pieter J; Heslenfeld, Dirk J; Oosterlaan, Jaap; Faraone, Stephen V; Buitelaar, Jan K; Hartman, Catharina A

    2016-01-01

    Smaller total brain and subcortical volumes have been linked to psychopathology including attention-deficit/hyperactivity disorder (ADHD). Identifying mechanisms underlying these alterations, therefore, is of great importance. We investigated the role of gene-environment interactions (GxE) in interindividual variability of total gray matter (GM), caudate, and putamen volumes. Brain volumes were derived from structural magnetic resonance imaging scans in participants with (N = 312) and without ADHD (N = 437) from N = 402 families (age M = 17.00, SD = 3.60). GxE effects between DAT1, 5-HTT, and DRD4 and social environments (maternal expressed warmth and criticism; positive and deviant peer affiliation) as well as the possible moderating effect of age were examined using linear mixed modeling. We also tested whether findings depended on ADHD severity. Deviant peer affiliation was associated with lower caudate volume. Participants with low deviant peer affiliations had larger total GM volumes with increasing age. Likewise, developmentally sensitive GxE effects were found on total GM and putamen volume. For total GM, differential age effects were found for DAT1 9-repeat and HTTLPR L/L genotypes, depending on the amount of positive peer affiliation. For putamen volume, DRD4 7-repeat carriers and DAT1 10/10 homozygotes showed opposite age relations depending on positive peer affiliation and maternal criticism, respectively. All results were independent of ADHD severity. The presence of differential age-dependent GxE effects might explain the diverse and sometimes opposing results of environmental and genetic effects on brain volumes observed so far.

  2. Developmentally Sensitive Interaction Effects of Genes and the Social Environment on Total and Subcortical Brain Volumes.

    Directory of Open Access Journals (Sweden)

    Jennifer S Richards

    Full Text Available Smaller total brain and subcortical volumes have been linked to psychopathology including attention-deficit/hyperactivity disorder (ADHD. Identifying mechanisms underlying these alterations, therefore, is of great importance. We investigated the role of gene-environment interactions (GxE in interindividual variability of total gray matter (GM, caudate, and putamen volumes. Brain volumes were derived from structural magnetic resonance imaging scans in participants with (N = 312 and without ADHD (N = 437 from N = 402 families (age M = 17.00, SD = 3.60. GxE effects between DAT1, 5-HTT, and DRD4 and social environments (maternal expressed warmth and criticism; positive and deviant peer affiliation as well as the possible moderating effect of age were examined using linear mixed modeling. We also tested whether findings depended on ADHD severity. Deviant peer affiliation was associated with lower caudate volume. Participants with low deviant peer affiliations had larger total GM volumes with increasing age. Likewise, developmentally sensitive GxE effects were found on total GM and putamen volume. For total GM, differential age effects were found for DAT1 9-repeat and HTTLPR L/L genotypes, depending on the amount of positive peer affiliation. For putamen volume, DRD4 7-repeat carriers and DAT1 10/10 homozygotes showed opposite age relations depending on positive peer affiliation and maternal criticism, respectively. All results were independent of ADHD severity. The presence of differential age-dependent GxE effects might explain the diverse and sometimes opposing results of environmental and genetic effects on brain volumes observed so far.

  3. Forecasting on the total volumes of Malaysia's imports and exports by multiple linear regression

    Science.gov (United States)

    Beh, W. L.; Yong, M. K. Au

    2017-04-01

    This study is to give an insight on the doubt of the important of macroeconomic variables that affecting the total volumes of Malaysia's imports and exports by using multiple linear regression (MLR) analysis. The time frame for this study will be determined by using quarterly data of the total volumes of Malaysia's imports and exports covering the period between 2000-2015. The macroeconomic variables will be limited to eleven variables which are the exchange rate of US Dollar with Malaysia Ringgit (USD-MYR), exchange rate of China Yuan with Malaysia Ringgit (RMB-MYR), exchange rate of European Euro with Malaysia Ringgit (EUR-MYR), exchange rate of Singapore Dollar with Malaysia Ringgit (SGD-MYR), crude oil prices, gold prices, producer price index (PPI), interest rate, consumer price index (CPI), industrial production index (IPI) and gross domestic product (GDP). This study has applied the Johansen Co-integration test to investigate the relationship among the total volumes to Malaysia's imports and exports. The result shows that crude oil prices, RMB-MYR, EUR-MYR and IPI play important roles in the total volumes of Malaysia's imports. Meanwhile crude oil price, USD-MYR and GDP play important roles in the total volumes of Malaysia's exports.

  4. Genetic Schizophrenia Risk Variants Jointly Modulate Total Brain and White Matter Volume

    DEFF Research Database (Denmark)

    Terwisscha van Scheltinga, Afke F; Bakker, Steven C; van Haren, Neeltje E M

    2013-01-01

    with total brain volume (R(2)=.048, p=1.6×10(-4)) and white matter volume (R(2)=.051, p=8.6×10(-5)) equally in patients and control subjects. The number of (independent) SNPs that substantially influenced both disease risk and white matter (n=2020) was much smaller than the entire set of SNPs that modulated...... modulating schizophrenia and brain volume. METHODS: Odds ratios for genome-wide SNP data were calculated in the sample collected by the Psychiatric Genome-wide Association Study Consortium (8690 schizophrenia patients and 11,831 control subjects, excluding subjects from the present study). These were used...

  5. Total brain, cortical and white matter volumes in children previously treated with glucocorticoids

    DEFF Research Database (Denmark)

    Holm, Sara K; Madsen, Kathrine S; Vestergaard, Martin

    2018-01-01

    BACKGROUND: Perinatal exposure to glucocorticoids and elevated endogenous glucocorticoid-levels during childhood can have detrimental effects on the developing brain. Here, we examined the impact of glucocorticoid-treatment during childhood on brain volumes. METHODS: Thirty children and adolescents...... with rheumatic or nephrotic disease previously treated with glucocorticoids and 30 controls matched on age, sex, and parent education underwent magnetic resonance imaging (MRI) of the brain. Total cortical grey and white matter, brain, and intracranial volume, and total cortical thickness and surface area were...... were mainly driven by the children with rheumatic disease. Total cortical thickness and cortical surface area did not significantly differ between groups. We found no significant associations between glucocorticoid-treatment variables and volumetric measures. CONCLUSION: Observed smaller total brain...

  6. Skeletal and total body volumes of human fetuses: assessment of reference data by spiral CT

    International Nuclear Information System (INIS)

    Braillon, Pierre M.; Buenerd, Annie; Bouvier, Raymonde; Lapillonne, Alexandre

    2002-01-01

    Objective: To define reference data for skeletal and total body volumes of normal human fetuses. Materials and methods: Spiral CT was used to assess the skeletal and total body volumes of 31 normal human stillborn infants with gestational age (GA) and body weight (BW) ranging from 14 to 41.5 weeks and 22 to 3,760 g, respectively. CT scans (slice thickness 2.7 mm, pitch 0.7) were performed within the first 24 h after delivery. Precise bone and soft-tissue windows were defined from analysis of the density along the diaphysis of the fetal long bones and from the measurement of a phantom that mimics soft tissues. Lengths and volumes were obtained from 3D reconstructions. The femur lengths measured from CT images (FLct) were compared with those provided by US studies (FLus). Results: Significant correlations (r>0.9) were found between BW, measured volumes of the entire skeleton or head, long-bone lengths, biparietal diameter and GA. Strong linear correlations (r>0.98) were observed between FLct and FLus. Conclusions: Skeletal and total body volume values obtained using spiral CT were significantly correlated with fetal biometric measurements. These data could complement those obtained in obstetric investigations with US. (orig.)

  7. Environmental and ice volume changes based on seismic stratigraphy in Sabrina Coast, East Antarctica: Preliminary results from NBP1402

    Science.gov (United States)

    Gulick, S. P. S.; Fernandez-Vasquez, R. A.; Frederick, B.; Saustrup, S., Sr.; Domack, E. W.; Lavoie, C.; Shevenell, A.; Blankenship, D. D.; Leventer, A.

    2014-12-01

    In 2014, the R/V Nathaniel B. Palmer (NBP1402) sailed to a virtually unexplored continental shelf along the Sabrina Coast, East Antarctica. The shelf contains the sedimentary record of environmental and ice volume changes within the Aurora Subglacial Basin (ASB), which is presently occupied by ~7 m sea level-rise equivalent of ice. We acquired 750 km of high-resolution seismic data proximal to the Reynolds Trough and Moscow University Ice Shelf glacial systems west of the Dalton Ice Tongue using dual 45/45 cu. in. G.I. guns and a 24 ch. streamer with 3.125 m groups providing a vertical resolution of ~3 m simultaneously with CHIRP data. These are the first images of this margin acquired and show a remarkable set of sequence stratigraphic transitions. Crystalline basement is at the seafloor landward and buried seaward with a transition to smoother reflection interface. Reflective sedimentary strata overlie the basement, dip seaward, and are capped by a landward-dipping regional angular unconformity. Above this are a series of transparent seismic facies that, along with the middle to outer shelf seafloor, dip landward towards a shelf-oblique glacial trough. The older, seaward-dipping strata include a deeper series of units that display at least three stratal architectures interpreted to be shelf deltas implying a pre-glacial, fluvial environment within the drainage basin. Above these sequences, the seismic facies transition to surfaces exhibiting significant erosion, small u-shaped valleys, and channel fill sequences, all of which are reminiscent of temperate glacial features. We interpret these sequences as including sub-ice tunnel valleys and grounding zone wedges with interspersed non-glacial to pro-glacial deposits. Increasing glaciogenic facies upsection suggests a gradual fluvial to glacial transition and increasing glacial extent with time. The subsequent transition to ice sheets is marked by erosion to basement landward and the angular unconformity seaward

  8. Measurement of thyroid volume, iodine concentration and total iodine content by CT and its clinical significance

    International Nuclear Information System (INIS)

    Nakaji, Shunsuke; Imanishi, Yoshimasa; Okamoto, Kyouko; Shinagawa, Toshihito

    2007-01-01

    Recently, Imanishi et al have developed new CT software for quantitative in vivo measurement of thyroid iodine. Using a CT system with the software, we measured volume, iodine concentration and total iodine content of thyroids in 63 controls and 435 patients with various diffuse thyroid diseases and thyroid nodules. In controls, all of them showed no difference between the sexes. Although the iodine concentration of the thyroid showed no difference among children, adults and seniles, the volume and total iodine content of the thyroid appeared smaller in children and seniles than in adults. In addition, although the volume and iodine concentration of the thyroid had two peaks in distribution, the total iodine content had almost normal distribution. Normal range of volume, iodine concentration and total iodine content in adults were 5.2-15.5 cm 3 , 0.28831-0.85919 mg/cm 3 and 2.35-11.69 mg, respectively. In thyroid nodule, there is no significant difference in volume, iodine concentration and total iodine content between benign and malignant nodules. All nodules with iodine concentration of less than 0.00007 mg/cm 3 were benign. No thyroid was higher in iodine concentration than the normal range although the thyroid was lower in 78.7% of patients with diffuse thyroid diseases. In all thyroids with increasing iodine concentration and total iodine content in medication course, thyroidal symptoms and signs were uncontrollable by the medication. In 43.8% of patients with long-period systemic diseases, the thyroid showed abnormality in any of the three. We concluded that quantitative in vivo measurement of thyroid iodine by CT could assist the diagnosis of thyroid diseases and decision of therapeutic methods. (author)

  9. Constraints on ice volume changes of the WAIS and Ross Ice Shelf since the LGM based on cosmogenic exposure ages in the Darwin-Hatherton glacial system of the Transantarctic Mountains

    Science.gov (United States)

    Fink, David; Storey, Bryan; Hood, David; Joy, Kurt; Shulmeister, James

    2010-05-01

    Quantitative assessment of the spatial and temporal scale of ice volume change of the West Antarctic ice sheet (WAIS) and Ross Ice Shelf since the last glacial maximum (LGM) ~20 ka is essential to accurately predict ice sheet response to current and future climate change. Although global sea level rose by approximately 120 metres since the LGM, the contribution of polar ice sheets is uncertain and the timing of any such contribution is controversial. Mackintosh et al (2007) suggest that sectors of the EAIS, similar to those studied at Framnes Mountains where the ice sheet slowly calves at coastal margins, have made marginal contributions to global sea-level rise between 13 and 7 ka. In contrast, Stone et al (2003) document continuing WAIS decay during the mid-late Holocene, raising the question of what was the response of the WAIS since LGM and into the Holocene. Terrestrial evidence is restricted to sparse coastal oasis and ice free mountains which archive limits of former ice advances. Mountain ranges flanking the Darwin-Hatherton glaciers exhibit well-defined moraines, weathering signatures, boulder rich plateaus and glacial tills, which preserve the evidence of advance and retreat of the ice sheet during previous glacial cycles. Previous studies suggest a WAIS at the LGM in this location to be at least 1,000 meters thicker than today. As part of the New Zealand Latitudinal Gradient Project along the Transantarctic, we collected samples for cosmogenic exposure dating at a) Lake Wellman area bordering the Hatherton Glacier, (b) Roadend Nunatak at the confluence of the Darwin and Hatherton glaciers and (c) Diamond Hill which is positioned at the intersection of the Ross Ice Shelf and Darwin Glacier outlet. While the technique of exposure dating is very successful in mid-latitude alpine glacier systems, it is more challenging in polar ice-sheet regions due to the prevalence of cold-based ice over-riding events and absence of outwash processes which removes

  10. Extracellular space, blood volume, and the early dumping syndrome after total gastrectomy

    Energy Technology Data Exchange (ETDEWEB)

    Miholic, J.; Reilmann, L.; Meyer, H.J.; Koerber, H.K.; Kotzerke, J.; Hecker, H. (Medzinische Hochschule Hannover (Germany, F.R.))

    1990-10-01

    Extracellular space and blood volume were measured using 82Br dilution and 51Cr-tagged erythrocytes in 24 tumor-free patients after total gastrectomy. Eleven of the patients suffered from early dumping. Age, blood volume, and extracellular space were significantly smaller in dumpers (P less than 0.05). The dumping score could be predicted by a multiple regression model considering blood volume per lean body mass and extracellular space (r = 0.637; P = 0.0039). Rapid (t1/2 less than 360 seconds) emptying of the gastric substitute, assessed using a 99Tc-labeled solid test meal, was significantly associated with dumping in addition to extracellular space and blood volume (r = 0.876; P = 0.0018). Both rapid emptying and a narrow extracellular space seem to contribute to the early dumping syndrome.

  11. A Novel Grey Wave Method for Predicting Total Chinese Trade Volume

    Directory of Open Access Journals (Sweden)

    Kedong Yin

    2017-12-01

    Full Text Available The total trade volume of a country is an important way of appraising its international trade situation. A prediction based on trade volume will help enterprises arrange production efficiently and promote the sustainability of the international trade. Because the total Chinese trade volume fluctuates over time, this paper proposes a Grey wave forecasting model with a Hodrick–Prescott filter (HP filter to forecast it. This novel model first parses time series into long-term trend and short-term cycle. Second, the model uses a general GM (1,1 to predict the trend term and the Grey wave forecasting model to predict the cycle term. Empirical analysis shows that the improved Grey wave prediction method provides a much more accurate forecast than the basic Grey wave prediction method, achieving better prediction results than autoregressive moving average model (ARMA.

  12. 29 CFR 779.253 - What is included in computing the total annual inflow volume.

    Science.gov (United States)

    2010-07-01

    ... FAIR LABOR STANDARDS ACT AS APPLIED TO RETAILERS OF GOODS OR SERVICES Employment to Which the Act May... taxes and other charges which the enterprise must pay for such goods. Generally, all charges will be... computing the total annual inflow volume. The goods which the establishment purchases or receives for resale...

  13. Does early tetralogy of Fallot total correction give better final lung volumes?

    Science.gov (United States)

    Sadeghi, Hasan Allah; Miri, Seyed Reza; Bakhshandeh, Hooman; Mirmesdagh, Yalda; Paziraee, Nazita

    2013-06-01

    Pulmonary blood flow may affect lung development in adulthood. Early total correction of tetralogy of Fallot may affect development of final lung volumes. We evaluated the effect of age at total correction on lung volumes years after the operation. In a retrospective cohort study on patients with totally corrected tetralogy of Fallot (mean age, 13.40 years at the time of follow-up), forced vital capacity, slow vital capacity, forced expiratory volume in 1 s, and other parameters were measured 154.8 ± 46.25 months after the operation. Comparison were made of 3 groups: ≤2-, 2-8-, and >8-years old at the time of total correction surgery. Among 322 enrolled patients, the mean values of the follow-up spirometry results in ≤2-, 2-8-, >8-year-olds and the percentage of predicted values were respectively: vital capacity: 4.46 ± 0.57 L (107% ± 10.96%), 3.89 ± 0.58 L (91.10% ± 12.25%), 3.25 ± 0.48 L (82.35% ± 10.62%), p volume in 1 s: 4.22 ± 0.63 L (104.84% ± 13.64%), 3.66 ± 0.58 L (90.61% ± 12.59%), 3.02 ± 0.48 L (84.31% ± 12%), p volumes and capacities. It is better to consider total correction for all tetralogy of Fallot patients below 2-years old, or at least below 8-years old, if it is technically possible.

  14. Tranexamic Acid Reduced the Percent of Total Blood Volume Lost During Adolescent Idiopathic Scoliosis Surgery.

    Science.gov (United States)

    Jones, Kristen E; Butler, Elissa K; Barrack, Tara; Ledonio, Charles T; Forte, Mary L; Cohn, Claudia S; Polly, David W

    2017-01-01

    Multilevel posterior spine fusion is associated with significant intraoperative blood loss. Tranexamic acid is an antifibrinolytic agent that reduces intraoperative blood loss. The goal of this study was to compare the percent of total blood volume lost during posterior spinal fusion (PSF) with or without tranexamic acid in patients with adolescent idiopathic scoliosis (AIS). Thirty-six AIS patients underwent PSF in 2011-2014; the last half (n=18) received intraoperative tranexamic acid. We retrieved relevant demographic, hematologic, intraoperative and outcomes information from medical records. The primary outcome was the percent of total blood volume lost, calculated from estimates of intraoperative blood loss (numerator) and estimated total blood volume per patient (denominator, via Nadler's equations). Unadjusted outcomes were compared using standard statistical tests. Tranexamic acid and no-tranexamic acid groups were similar (all p>0.05) in mean age (16.1 vs. 15.2 years), sex (89% vs. 83% female), body mass index (22.2 vs. 20.2 kg/m2), preoperative hemoglobin (13.9 vs. 13.9 g/dl), mean spinal levels fused (10.5 vs. 9.6), osteotomies (1.6 vs. 0.9) and operative duration (6.1 hours, both). The percent of total blood volume lost (TBVL) was significantly lower in the tranexamic acid-treated vs. no-tranexamic acid group (median 8.23% vs. 14.30%, p = 0.032); percent TBVL per level fused was significantly lower with tranexamic acid than without it (1.1% vs. 1.8%, p=0.048). Estimated blood loss (milliliters) was similar across groups. Tranexamic acid significantly reduced the percentage of total blood volume lost versus no tranexamic acid in AIS patients who underwent PSF using a standardized blood loss measure.Level of Evidence: 3. Institutional Review Board status: This medical record chart review (minimal risk) study was approved by the University of Minnesota Institutional Review Board.

  15. Effect of knee joint icing on knee extension strength and knee pain early after total knee arthroplasty: a randomized cross-over study.

    Science.gov (United States)

    Holm, Bente; Husted, Henrik; Kehlet, Henrik; Bandholm, Thomas

    2012-08-01

    To investigate the acute effect of knee joint icing on knee extension strength and knee pain in patients shortly after total knee arthroplasty. A prospective, single-blinded, randomized, cross-over study. A fast-track orthopaedic arthroplasty unit at a university hospital. Twenty patients (mean age 66 years; 10 women) scheduled for primary unilateral total knee arthroplasty. The patients were treated on two days (day 7 and day 10) postoperatively. On one day they received 30 minutes of knee icing (active treatment) and on the other day they received 30 minutes of elbow icing (control treatment). The order of treatments was randomized. Maximal knee extension strength (primary outcome), knee pain at rest and knee pain during the maximal knee extensions were measured 2-5 minutes before and 2-5 minutes after both treatments by an assessor blinded for active or control treatment. The change in knee extension strength associated with knee icing was not significantly different from that of elbow icing (knee icing change (mean (1 SD)) -0.01 (0.07) Nm/kg, elbow icing change -0.02 (0.07) Nm/kg, P = 0.493). Likewise, the changes in knee pain at rest (P = 0.475), or knee pain during the knee extension strength measurements (P = 0.422) were not different between treatments. In contrast to observations in experimental knee effusion models and inflamed knee joints, knee joint icing for 30 minutes shortly after total knee arthroplasty had no acute effect on knee extension strength or knee pain.

  16. 21 CFR 201.323 - Aluminum in large and small volume parenterals used in total parenteral nutrition.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 4 2010-04-01 2010-04-01 false Aluminum in large and small volume parenterals... for Specific Drug Products § 201.323 Aluminum in large and small volume parenterals used in total parenteral nutrition. (a) The aluminum content of large volume parenteral (LVP) drug products used in total...

  17. Effects of respiratory rate and tidal volume on gas exchange in total liquid ventilation.

    Science.gov (United States)

    Bull, Joseph L; Tredici, Stefano; Fujioka, Hideki; Komori, Eisaku; Grotberg, James B; Hirschl, Ronald B

    2009-01-01

    Using a rabbit model of total liquid ventilation (TLV), and in a corresponding theoretical model, we compared nine tidal volume-respiratory rate combinations to identify a ventilator strategy to maximize gas exchange, while avoiding choked flow, during TLV. Nine different ventilation strategies were tested in each animal (n = 12): low [LR = 2.5 breath/min (bpm)], medium (MR = 5 bpm), or high (HR = 7.5 bpm) respiratory rates were combined with a low (LV = 10 ml/kg), medium (MV = 15 ml/kg), or high (HV = 20 ml/kg) tidal volumes. Blood gases and partial pressures, perfluorocarbon gas content, and airway pressures were measured for each combination. Choked flow occurred in all high respiratory rate-high volume animals, 71% of high respiratory rate-medium volume (HRMV) animals, and 50% of medium respiratory rate-high volume (MRHV) animals but in no other combinations. Medium respiratory rate-medium volume (MRMV) resulted in the highest gas exchange of the combinations that did not induce choke. The HRMV and MRHV animals that did not choke had similar or higher gas exchange than MRMV. The theory predicted this behavior, along with spatial and temporal variations in alveolar gas partial pressures. Of the combinations that did not induce choked flow, MRMV provided the highest gas exchange. Alveolar gas transport is diffusion dominated and rapid during gas ventilation but is convection dominated and slow during TLV. Consequently, the usual alveolar gas equation is not applicable for TLV.

  18. MRI estimation of total renal volume demonstrates significant association with healthy donor weight

    International Nuclear Information System (INIS)

    Cohen, Emil I.; Kelly, Sarah A.; Edye, Michael; Mitty, Harold A.; Bromberg, Jonathan S.

    2009-01-01

    Purpose: The purpose of this study was to correlate total renal volume (TRV) calculations, obtained through the voxel-count method and ellipsoid formula with various physical characteristics. Materials and methods: MRI reports and physical examination from 210 healthy kidney donors (420 kidneys), on whom renal volumes were obtained using the voxel-count method, were retrospectively reviewed. These values along with ones obtained through a more traditional method (ellipsoid formula) were correlated with subject height, body weight, body mass index (BMI), and age. Results: TRV correlated strongly with body weight (r = 0.7) and to a lesser degree with height, age, or BMI (r = 0.5, -0.2, 0.3, respectively). The left kidney volume was greater than the right, on average (p < 0.001). The ellipsoid formula method over-estimated renal volume by 17% on average which was significant (p < 0.001). Conclusions: Body weight was the physical characteristic which demonstrated the strongest correlation with renal volume in healthy subjects. Given this finding, a formula was derived for estimating the TRV for a given patient based on the his or her weight: TRV = 2.96 x weight (kg) + 113 ± 64.

  19. Sea Ice

    Science.gov (United States)

    Perovich, D.; Gerland, S.; Hendricks, S.; Meier, Walter N.; Nicolaus, M.; Richter-Menge, J.; Tschudi, M.

    2013-01-01

    During 2013, Arctic sea ice extent remained well below normal, but the September 2013 minimum extent was substantially higher than the record-breaking minimum in 2012. Nonetheless, the minimum was still much lower than normal and the long-term trend Arctic September extent is -13.7 per decade relative to the 1981-2010 average. The less extreme conditions this year compared to 2012 were due to cooler temperatures and wind patterns that favored retention of ice through the summer. Sea ice thickness and volume remained near record-low levels, though indications are of slightly thicker ice compared to the record low of 2012.

  20. Sixty volumes of the Journal du Conseil / ICES Journal of Marine Science

    NARCIS (Netherlands)

    Ramster, J.; Daan, N.; Frid, C.; Megrey, B.; Payne, A.; Pepin, P.

    2003-01-01

    Article 1 of the ICES Convention of 1964 sets out the fundamental purposes of the Council and includes as the third and final point: "to publish or otherwise disseminate the results of research and investigations carried out under its auspices or to encourage the publication thereof". Publication

  1. Grid-connected ICES: preliminary feasibility analysis and evaluation. Volume 2. Final report

    Energy Technology Data Exchange (ETDEWEB)

    1977-06-30

    The HEAL Complex in New Orleans will serve as a Demonstration Community for which the ICES Demonstration System will be designed. The complex is a group of hospitals, clinics, research facilities, and medical educational facilities. The five tasks reported on are: preliminary energy analysis; preliminary institutional assessment; conceptual design; firming-up of commitments; and detailed work management plan.

  2. Effect of knee joint icing on knee extension strength and knee pain early after total knee arthroplasty: a randomized cross-over study

    DEFF Research Database (Denmark)

    Holm, Bente; Husted, Henrik; Kehlet, Henrik

    2012-01-01

    Objective: To investigate the acute effect of knee joint icing on knee extension strength and knee pain in patients shortly after total knee arthroplasty.Design: A prospective, single-blinded, randomized, cross-over study.Setting: A fast-track orthopaedic arthroplasty unit at a university hospital.......Participants: Twenty patients (mean age 66 years; 10 women) scheduled for primary unilateral total knee arthroplasty.Interventions: The patients were treated on two days (day 7 and day 10) postoperatively. On one day they received 30 minutes of knee icing (active treatment) and on the other day they received 30...... minutes of elbow icing (control treatment). The order of treatments was randomized.Main outcome measures: Maximal knee extension strength (primary outcome), knee pain at rest and knee pain during the maximal knee extensions were measured 2-5 minutes before and 2-5 minutes after both treatments...

  3. Feasibility of Commercially Available, Fully Automated Hepatic CT Volumetry for Assessing Both Total and Territorial Liver Volumes in Liver Transplantation

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Cheong Il; Kim, Se Hyung; Rhim, Jung Hyo; Yi, Nam Joon; Suh, Kyung Suk; Lee, Jeong Min; Han, Joon Koo; Choi, Byung Ihn [Seoul National University Hospital, Seoul (Korea, Republic of)

    2013-02-15

    To assess the feasibility of commercially-available, fully automated hepatic CT volumetry for measuring both total and territorial liver volumes by comparing with interactive manual volumetry and measured ex-vivo liver volume. For the assessment of total and territorial liver volume, portal phase CT images of 77 recipients and 107 donors who donated right hemiliver were used. Liver volume was measured using both the fully automated and interactive manual methods with Advanced Liver Analysis software. The quality of the automated segmentation was graded on a 4-point scale. Grading was performed by two radiologists in consensus. For the cases with excellent-to-good quality, the accuracy of automated volumetry was compared with interactive manual volumetry and measured ex-vivo liver volume which was converted from weight using analysis of variance test and Pearson's or Spearman correlation test. Processing time for both automated and interactive manual methods was also compared. Excellent-to-good quality of automated segmentation for total liver and right hemiliver was achieved in 57.1% (44/77) and 17.8% (19/107), respectively. For both total and right hemiliver volumes, there were no significant differences among automated, manual, and ex-vivo volumes except between automate volume and manual volume of the total liver (p = 0.011). There were good correlations between automate volume and ex-vivo liver volume ({gamma}= 0.637 for total liver and {gamma}= 0.767 for right hemiliver). Both correlation coefficients were higher than those with manual method. Fully automated volumetry required significantly less time than interactive manual method (total liver: 48.6 sec vs. 53.2 sec, right hemiliver: 182 sec vs. 244.5 sec). Fully automated hepatic CT volumetry is feasible and time-efficient for total liver volume measurement. However, its usefulness for territorial liver volumetry needs to be improved.

  4. Feasibility of Commercially Available, Fully Automated Hepatic CT Volumetry for Assessing Both Total and Territorial Liver Volumes in Liver Transplantation

    International Nuclear Information System (INIS)

    Shin, Cheong Il; Kim, Se Hyung; Rhim, Jung Hyo; Yi, Nam Joon; Suh, Kyung Suk; Lee, Jeong Min; Han, Joon Koo; Choi, Byung Ihn

    2013-01-01

    To assess the feasibility of commercially-available, fully automated hepatic CT volumetry for measuring both total and territorial liver volumes by comparing with interactive manual volumetry and measured ex-vivo liver volume. For the assessment of total and territorial liver volume, portal phase CT images of 77 recipients and 107 donors who donated right hemiliver were used. Liver volume was measured using both the fully automated and interactive manual methods with Advanced Liver Analysis software. The quality of the automated segmentation was graded on a 4-point scale. Grading was performed by two radiologists in consensus. For the cases with excellent-to-good quality, the accuracy of automated volumetry was compared with interactive manual volumetry and measured ex-vivo liver volume which was converted from weight using analysis of variance test and Pearson's or Spearman correlation test. Processing time for both automated and interactive manual methods was also compared. Excellent-to-good quality of automated segmentation for total liver and right hemiliver was achieved in 57.1% (44/77) and 17.8% (19/107), respectively. For both total and right hemiliver volumes, there were no significant differences among automated, manual, and ex-vivo volumes except between automate volume and manual volume of the total liver (p = 0.011). There were good correlations between automate volume and ex-vivo liver volume (γ= 0.637 for total liver and γ= 0.767 for right hemiliver). Both correlation coefficients were higher than those with manual method. Fully automated volumetry required significantly less time than interactive manual method (total liver: 48.6 sec vs. 53.2 sec, right hemiliver: 182 sec vs. 244.5 sec). Fully automated hepatic CT volumetry is feasible and time-efficient for total liver volume measurement. However, its usefulness for territorial liver volumetry needs to be improved.

  5. A sea ice model for the marginal ice zone with an application to the Greenland Sea

    DEFF Research Database (Denmark)

    Pedersen, Leif Toudal; Coon, Max D.

    2004-01-01

    A model is presented that describes the formation, transport, and desalinization of frazil and pancake ice as it is formed in marginal seas. This model uses as input the total ice concentration evaluated from Special Sensor Microwave Imager and wind speed and direction. The model calculates...... the areal concentration, thickness, volume concentration, and salinity of frazil ice as well as the areal concentration, thickness, and salinity of pancakes. A simple parameterization for the Odden region of the Greenland Sea is presented. The model is run for the winter of 1996-1997. There are direct...... observations of the thickness and salinity of pancakes and the volume concentration of frazil ice to compare with the model. The model results compare very well with the measured data. This new ice model can be tuned to work in marginal seas elsewhere to calculate ice thickness, motion, and brine rejection...

  6. Automated CT-based segmentation and quantification of total intracranial volume

    Energy Technology Data Exchange (ETDEWEB)

    Aguilar, Carlos; Wahlund, Lars-Olof; Westman, Eric [Karolinska Institute, Department of Neurobiology, Care Sciences and Society (NVS), Division of Clinical Geriatrics, Stockholm (Sweden); Edholm, Kaijsa; Cavallin, Lena; Muller, Susanne; Axelsson, Rimma [Karolinska Institute, Department of Clinical Science, Intervention and Technology, Division of Medical Imaging and Technology, Stockholm (Sweden); Karolinska University Hospital in Huddinge, Department of Radiology, Stockholm (Sweden); Simmons, Andrew [King' s College London, Institute of Psychiatry, London (United Kingdom); NIHR Biomedical Research Centre for Mental Health and Biomedical Research Unit for Dementia, London (United Kingdom); Skoog, Ingmar [Gothenburg University, Department of Psychiatry and Neurochemistry, The Sahlgrenska Academy, Gothenburg (Sweden); Larsson, Elna-Marie [Uppsala University, Department of Surgical Sciences, Radiology, Akademiska Sjukhuset, Uppsala (Sweden)

    2015-11-15

    To develop an algorithm to segment and obtain an estimate of total intracranial volume (tICV) from computed tomography (CT) images. Thirty-six CT examinations from 18 patients were included. Ten patients were examined twice the same day and eight patients twice six months apart (these patients also underwent MRI). The algorithm combines morphological operations, intensity thresholding and mixture modelling. The method was validated against manual delineation and its robustness assessed from repeated imaging examinations. Using automated MRI software, the comparability with MRI was investigated. Volumes were compared based on average relative volume differences and their magnitudes; agreement was shown by a Bland-Altman analysis graph. We observed good agreement between our algorithm and manual delineation of a trained radiologist: the Pearson's correlation coefficient was r = 0.94, tICVml[manual] = 1.05 x tICVml[automated] - 33.78 (R{sup 2} = 0.88). Bland-Altman analysis showed a bias of 31 mL and a standard deviation of 30 mL over a range of 1265 to 1526 mL. tICV measurements derived from CT using our proposed algorithm have shown to be reliable and consistent compared to manual delineation. However, it appears difficult to directly compare tICV measures between CT and MRI. (orig.)

  7. Automated CT-based segmentation and quantification of total intracranial volume

    International Nuclear Information System (INIS)

    Aguilar, Carlos; Wahlund, Lars-Olof; Westman, Eric; Edholm, Kaijsa; Cavallin, Lena; Muller, Susanne; Axelsson, Rimma; Simmons, Andrew; Skoog, Ingmar; Larsson, Elna-Marie

    2015-01-01

    To develop an algorithm to segment and obtain an estimate of total intracranial volume (tICV) from computed tomography (CT) images. Thirty-six CT examinations from 18 patients were included. Ten patients were examined twice the same day and eight patients twice six months apart (these patients also underwent MRI). The algorithm combines morphological operations, intensity thresholding and mixture modelling. The method was validated against manual delineation and its robustness assessed from repeated imaging examinations. Using automated MRI software, the comparability with MRI was investigated. Volumes were compared based on average relative volume differences and their magnitudes; agreement was shown by a Bland-Altman analysis graph. We observed good agreement between our algorithm and manual delineation of a trained radiologist: the Pearson's correlation coefficient was r = 0.94, tICVml[manual] = 1.05 x tICVml[automated] - 33.78 (R 2 = 0.88). Bland-Altman analysis showed a bias of 31 mL and a standard deviation of 30 mL over a range of 1265 to 1526 mL. tICV measurements derived from CT using our proposed algorithm have shown to be reliable and consistent compared to manual delineation. However, it appears difficult to directly compare tICV measures between CT and MRI. (orig.)

  8. Synaptic vesicle exocytosis in hippocampal synaptosomes correlates directly with total mitochondrial volume

    Science.gov (United States)

    Ivannikov, Maxim V.; Sugimori, Mutsuyuki; Llinás, Rodolfo R.

    2012-01-01

    Synaptic plasticity in many regions of the central nervous system leads to the continuous adjustment of synaptic strength, which is essential for learning and memory. In this study, we show by visualizing synaptic vesicle release in mouse hippocampal synaptosomes that presynaptic mitochondria and specifically, their capacities for ATP production are essential determinants of synaptic vesicle exocytosis and its magnitude. Total internal reflection microscopy of FM1-43 loaded hippocampal synaptosomes showed that inhibition of mitochondrial oxidative phosphorylation reduces evoked synaptic release. This reduction was accompanied by a substantial drop in synaptosomal ATP levels. However, cytosolic calcium influx was not affected. Structural characterization of stimulated hippocampal synaptosomes revealed that higher total presynaptic mitochondrial volumes were consistently associated with higher levels of exocytosis. Thus, synaptic vesicle release is linked to the presynaptic ability to regenerate ATP, which itself is a utility of mitochondrial density and activity. PMID:22772899

  9. Safe total corporal contouring with large-volume liposuction for the obese patient.

    Science.gov (United States)

    Dhami, Lakshyajit D; Agarwal, Meenakshi

    2006-01-01

    The advent of the tumescent technique in 1987 allowed for safe total corporal contouring as an ambulatory, single-session megaliposuction with the patient under regional anesthesia supplemented by local anesthetic only in selected areas. Safety and aesthetic issues define large-volume liposuction as having a 5,000-ml aspirate, mega-volume liposuction as having an 8,000-ml aspirate, and giganto-volume liposuction as having an aspirate of 12,000 ml or more. Clinically, a total volume comprising 5,000 ml of fat and wetting solution aspirated during the procedure qualifies for megaliposuction/large-volume liposuction. Between September 2000 and August 2005, 470 cases of liposuction were managed. In 296 (63%) of the 470 cases, the total volume of aspirate exceeded 5 l (range, 5,000-22,000 ml). Concurrent limited or total-block lipectomy was performed in 70 of 296 cases (23.6%). Regional anesthesia with conscious sedation was preferred, except where liposuction targeted areas above the subcostal region (the upper trunk, lateral chest, gynecomastia, breast, arms, and face), or when the patient so desired. Tumescent infiltration was achieved with hypotonic lactated Ringer's solution, adrenalin, triamcinalone, and hyalase in all cases during the last one year of the series. This approach has clinically shown less tissue edema in the postoperative period than with conventional physiologic saline used in place of the Ringer's lactate solution. The amount injected varied from 1,000 to 8,000 ml depending on the size, site, and area. Local anesthetic was included only for the terminal portion of the tumescent mixture, wherever the subcostal regions were infiltrated. The aspirate was restricted to the unstained white/yellow fat, and the amount of fat aspirated did not have any bearing on the amount of solution infiltrated. There were no major complications, and no blood transfusions were administered. The hospital stay ranged from 8 to 24 h for both liposuction and liposuction

  10. Grid-connected ICES: preliminary feasibility analysis and evaluation. Volume 3. Final report

    Energy Technology Data Exchange (ETDEWEB)

    None

    1977-06-30

    Maps, charts, and drawings of the Demonstration Community for the grid-connected ICES project composed of the medical complex in New Orleans (HEAL) are presented in Appendix A. The physical profile of the existing buildings and site plans is included. Demand profiles for steam, electric, gas, etc. are presented in Appendix B with extensive tables and graphs. Air quality and noise pollution data are presented in Appendix C. Data on financing in Appendix D are presented and also texts and information on revenue bonds are given. The final appendix gives qualifications for personnel for HEAL; NOSPI; de Laureal Engineers, Inc.; and Orr-Schelen-Mayeron and Associates, Inc.

  11. The role of surgeon volume on patient outcome in total knee arthroplasty: a systematic review of the literature

    Directory of Open Access Journals (Sweden)

    Lau Rick L

    2012-12-01

    Full Text Available Abstract Background A number of factors have been identified as influencing total knee arthroplasty outcomes, including patient factors such as gender and medical comorbidity, technical factors such as alignment of the prosthesis, and provider factors such as hospital and surgeon procedure volumes. Recently, strategies aimed at optimizing provider factors have been proposed, including regionalization of total joint arthroplasty to higher volume centers, and adoption of volume standards. To contribute to the discussions concerning the optimization of provider factors and proposals to regionalize total knee arthroplasty practices, we undertook a systematic review to investigate the association between surgeon volume and primary total knee arthroplasty outcomes. Methods We performed a systematic review examining the association between surgeon volume and primary knee arthroplasty outcomes. To be included in the review, the study population had to include patients undergoing primary total knee arthroplasty. Studies had to report on the association between surgeon volume and primary total knee arthroplasty outcomes, including perioperative mortality and morbidity, patient-reported outcomes, or total knee arthroplasty implant survivorship. There were no restrictions placed on study design or language. Results Studies were variable in defining surgeon volume (‘low’: 5 to >70 total knee arthroplasty per year. Mortality rate, survivorship and thromboembolic events were not found to be associated with surgeon volume. We found a significant association between low surgeon volume and higher rate of infection (0.26% - 2.8% higher, procedure time (165 min versus 135 min, longer length of stay (0.4 - 2.13 days longer, transfusion rate (13% versus 4%, and worse patient reported outcomes. Conclusions Findings suggest a trend towards better outcomes for higher volume surgeons, but results must be interpreted with caution.

  12. Current self-reported symptoms of attention deficit/hyperactivity disorder are associated with total brain volume in healthy adults.

    Directory of Open Access Journals (Sweden)

    Martine Hoogman

    Full Text Available BACKGROUND: Reduced total brain volume is a consistent finding in children with Attention Deficit/Hyperactivity Disorder (ADHD. In order to get a better understanding of the neurobiology of ADHD, we take the first step in studying the dimensionality of current self-reported adult ADHD symptoms, by looking at its relation with total brain volume. METHODOLOGY/PRINCIPAL FINDINGS: In a sample of 652 highly educated adults, the association between total brain volume, assessed with magnetic resonance imaging, and current number of self-reported ADHD symptoms was studied. The results showed an association between these self-reported ADHD symptoms and total brain volume. Post-hoc analysis revealed that the symptom domain of inattention had the strongest association with total brain volume. In addition, the threshold for impairment coincides with the threshold for brain volume reduction. CONCLUSIONS/SIGNIFICANCE: This finding improves our understanding of the biological substrates of self-reported ADHD symptoms, and suggests total brain volume as a target intermediate phenotype for future gene-finding in ADHD.

  13. Total-dose radiation effects data for semiconductor devices. 1985 supplement. Volume 2, part A

    International Nuclear Information System (INIS)

    Martin, K.E.; Gauthier, M.K.; Coss, J.R.; Dantas, A.R.V.; Price, W.E.

    1986-05-01

    Steady-state, total-dose radiation test data, are provided in graphic format for use by electronic designers and other personnel using semiconductor devices in a radiation environment. The data were generated by JPL for various NASA space programs. This volume provides data on integrated circuits. The data are presented in graphic, tabular, and/or narrative format, depending on the complexity of the integrated circuit. Most tests were done using the JPL or Boeing electron accelerator (Dynamitron) which provides a steady-state 2.5 MeV electron beam. However, some radiation exposures were made with a cobalt-60 gamma ray source, the results of which should be regarded as only an approximate measure of the radiation damage that would be incurred by an equivalent electron dose

  14. Reference values for total blood volume and cardiac output in humans

    Energy Technology Data Exchange (ETDEWEB)

    Williams, L.R. [Indiana Univ., South Bend, IN (United States). Division of Liberal Arts and Sciences

    1994-09-01

    Much research has been devoted to measurement of total blood volume (TBV) and cardiac output (CO) in humans but not enough effort has been devoted to collection and reduction of results for the purpose of deriving typical or {open_quotes}reference{close_quotes} values. Identification of normal values for TBV and CO is needed not only for clinical evaluations but also for the development of biokinetic models for ultra-short-lived radionuclides used in nuclear medicine (Leggett and Williams 1989). The purpose of this report is to offer reference values for TBV and CO, along with estimates of the associated uncertainties that arise from intra- and inter-subject variation, errors in measurement techniques, and other sources. Reference values are derived for basal supine CO and TBV in reference adult humans, and differences associated with age, sex, body size, body position, exercise, and other circumstances are discussed.

  15. Blood volume, blood pressure and total body sodium: internal signalling and output control

    DEFF Research Database (Denmark)

    Bie, P

    2009-01-01

    Total body sodium and arterial blood pressure (ABP) are mutually dependent variables regulated by complex control systems. This review addresses the role of ABP in the normal control of sodium excretion (NaEx), and the physiological control of renin secretion. NaEx is a pivotal determinant of ABP......, and under experimental conditions, ABP is a powerful, independent controller of NaEx. Blood volume is a function of dietary salt intake; however, ABP is not, at least not in steady states. A transient increase in ABP after a step-up in sodium intake could provide a causal relationship between ABP...... and the regulation of NaEx via a hypothetical integrative control system. However, recent data show that subtle sodium loading (simulating salty meals) causes robust natriuresis without changes in ABP. Changes in ABP are not necessary for natriuresis. Normal sodium excretion is not regulated by pressure. Plasma...

  16. Total reference air kerma can accurately predict isodose surface volumes in cervix cancer brachytherapy. A multicenter study

    DEFF Research Database (Denmark)

    Nkiwane, Karen S; Andersen, Else; Champoudry, Jerome

    2017-01-01

    PURPOSE: To demonstrate that V60 Gy, V75 Gy, and V85 Gy isodose surface volumes can be accurately estimated from total reference air kerma (TRAK) in cervix cancer MRI-guided brachytherapy (BT). METHODS AND MATERIALS: 60 Gy, 75 Gy, and 85 Gy isodose surface volumes levels were obtained from treatm...

  17. The Search for Eight Glacial Cycles of Deep-Water Temperatures and Global ice Volume From the Southern Hemisphere

    Science.gov (United States)

    Ferretti, P.; Elderfield, H.; Greaves, M.; McCave, N.

    2007-12-01

    It has been recently suggested "a substantial portion of the marine 100-ky cycle that has been object of so much attention over the past quarter of a century is, in reality, a deep-water temperature signal and not an ice volume signal" (Shackleton, 2000). There are currently few records available of deep-water temperature variations during the Pleistocene and most of our understanding is inferred from the oxygen isotopic composition (δ18O) of benthic foraminifera from deep-sea sediments. However, variations in benthic δ18O reflect some combination of local to regional changes in water mass properties (largely deep- water temperature) as well as global changes in seawater δ18O (δ18Osw) resulting from the growth and decay of continental ice. Recent studies suggest that benthic foraminiferal Mg/Ca may be useful in reconstructing deep-water temperature changes, but the application of this method to benthic species has been hampered by a number of unresolved issues, such as uncertainties related to the calibration for benthic Mg at the coldest temperatures. Here we present deep-sea Mg/Ca and δ18O records for the past eight glacial cycles in benthic foraminiferal ( Uvigerina spp.) calcite from a marine sediment core recovered in the mid Southern latitudes. Ocean Drilling Program Site 1123 was retrieved from Chatham Rise, east of New Zealand in the Southwest Pacific Ocean (3290 m water depth). This site lies under the Deep Western Boundary Current (DWBC) that flows into the Pacific Ocean, and is responsible for most of the deep water in that ocean; DWBC strength is directly related to processes occurring around Antarctica. Temperatures derived via pore fluid modeling of the last glacial maximum are available from Site 1123 and represent an important tool to constrain deep-water temperatures estimates using Mg/Ca. In selected time slices, we measured B/Ca ratios in Uvigerina in order to gain information on the deep-water carbonate saturation state and have data of Mg

  18. Cumulates, Dykes and Pressure Solution in the Ice-Salt Mantle of Europa: Geological Consequences of Pressure Dependent Liquid Compositions and Volume Changes During Ice-Salt Melting Reactions.

    Science.gov (United States)

    Day, S.; Asphaug, E.; Bruesch, L.

    2002-12-01

    Water-salt analogue experiments used to investigate cumulate processes in silicate magmas, along with observations of sea ice and ice shelf behaviour, indicate that crystal-melt separation in water-salt systems is a rapid and efficient process even on scales of millimetres and minutes. Squeezing-out of residual melts by matrix compaction is also predicted to be rapid on geological timescales. We predict that the ice-salt mantle of Europa is likely to be strongly stratified, with a layered structure predictable from density and phase relationships between ice polymorphs, aqueous saline solutions and crystalline salts such as hydrated magnesium sulphates (determined experimentally by, inter alia, Hogenboom et al). A surface layer of water ice flotation cumulate will be separated from denser salt cumulates by a cotectic horizon. This cotectic horizon will be both the site of subsequent lowest-temperature melting and a level of neutral buoyancy for the saline melts produced. Initial melting will be in a narrow depth range owing to increasing melting temperature with decreasing pressure: the phase relations argue against direct melt-though to the surface unless vesiculation occurs. Overpressuring of dense melts due to volume expansion on cotectic melting is predicted to lead to lateral dyke emplacement and extension above the dyke tips. Once the liquid leaves the cotectic, melting of water ice will involve negative volume change. Impact-generated melts will drain downwards through the fractured zones beneath crater floors. A feature in the complex crater Mannan'an, with elliptical ring fractures around a conical depression with a central pit, bears a close resemblance to Icelandic glacier collapse cauldrons produced by subglacial eruptions. Other structures resembling Icelandic cauldrons occur along Europan banded structures, while resurgence of ice rubble within collapse structures may produce certain types of chaos region. More general contraction of the ice mantle

  19. Optimal repairable spare-parts procurement policy under total business volume discount environment

    International Nuclear Information System (INIS)

    Pascual, Rodrigo; Santelices, Gabriel; Lüer-Villagra, Armin; Vera, Jorge; Cawley, Alejandro Mac

    2017-01-01

    In asset intensive fields, where components are expensive and high system availability is required, spare parts procurement is often a critical issue. To gain competitiveness and market share is common for vendors to offer Total Business Volume Discounts (TBVD). Accordingly, companies must define the procurement and stocking policy of their spare parts in order to reduce procurement costs and increase asset availability. In response to those needs, this work presents an optimization model that maximizes the availability of the equipment under a TBVD environment, subject to a budget constraint. The model uses a single-echelon structure where parts can be repaired. It determines the optimal number of repairable spare parts to be stocked, giving emphasis on asset availability, procurement costs and service levels as the main decision criteria. A heuristic procedure that achieves high quality solutions in a fast and time-consistent way was implemented to improve the time required to obtain the model solution. Results show that using an optimal procurement policy of spare parts and accounting for TBVD produces better overall results and yields a better availability performance. - Highlights: • We propose a model for procurement of repairable components in single-echelon and business volume discount environments. • We used a mathematical model to develop a competitive heuristic that provides high quality solutions in very short times. • Our model places emphasis on using system availability, procurement costs and service levels as leading decision criteria. • The model can be used as an engine for a multi-criteria Decision Support System.

  20. Longitudinal Changes in Total Brain Volume in Schizophrenia: Relation to Symptom Severity, Cognition and Antipsychotic Medication

    NARCIS (Netherlands)

    Veijola, J.; Guo, J.Y.; Moilanen, J.S.; Jaaskelainen, E.; Miettunen, J.; Kyllonen, M.; Haapea, M.; Huhtaniska, S.; Alaraisanen, A.; Maki, P.; Kiviniemi, V.; Nikkinen, J.; Starck, T.; Remes, J.J.; Tanskanen, P.; Tervonen, O.; Wink, A.M.; Kehagia, A.; Suckling, J.; Kobayashi, H.; Barnett, J.H.; Barnes, A.; Koponen, H.J.; Jones, P.B.; Isohanni, M.; Murray, G.K.

    2014-01-01

    Studies show evidence of longitudinal brain volume decreases in schizophrenia. We studied brain volume changes and their relation to symptom severity, level of function, cognition, and antipsychotic medication in participants with schizophrenia and control participants from a general population

  1. Total volume and composition of fluid intake and mortality in older women: a cohort study

    Science.gov (United States)

    Lim, Wai H; Wong, Germaine; Lewis, Joshua R; Lok, Charmaine E; Polkinghorne, Kevan R; Hodgson, Jonathan; Lim, Ee M; Prince, Richard L

    2017-01-01

    Objectives The health benefits of ‘drinking at least 8 glasses of water a day” in healthy individuals are largely unproven. We aimed to examine the relationship between total fluid and the sources of fluid consumption, risk of rapid renal decline, cardiovascular disease (CVD) mortality and all-cause mortality in elderly women. Design, setting and participants We conducted a longitudinal analysis of a population-based cohort study of 1055 women aged ≥70 years residing in Australia. Main outcome measures The associations between total daily fluid intake (defined as total volume of beverage excluding alcohol and milk) and the types of fluid (water, black tea, coffee, milk and other fluids) measured as cups per day and rapid renal decline, CVD and all-cause mortality were assessed using adjusted logistic and Cox regression analyses. Results Over a follow-up period of 10 years, 70 (6.6%) experienced rapid renal decline and 362 (34.4%) died, of which 142 (13.5%) deaths were attributed to CVD. The median (IQR) intake of total fluid was 10.4 (8.5–12.5) cups per day, with water (median (IQR) 4 (2–6) cups per day) and black tea (median (IQR) 3 (1–4) cups per day) being the most frequent type of fluid consumed. Every cup per day higher intake of black tea was associated with adjusted HRs of 0.90 (95% CI 0.81 to 0.99) and 0.92 (95% CI 0.86 to 0.98) for CVD mortality and all-cause mortality, respectively. There were no associations between black tea intake and rapid renal decline, or between the quantity or type of other fluids, including water intake, and any clinical outcomes. Conclusions Habitual higher intake of black tea may potentially improve long-term health outcomes, independent of treating traditional CVD risk factors, but validation of our study findings is essential. PMID:28341683

  2. Trenton ICES: demonstration of a grid-connected integrated community energy system. Phase II. Volumes 1 and 2. Preliminary design of ICES system and analysis of community ownership

    Energy Technology Data Exchange (ETDEWEB)

    1978-03-22

    Preliminary design and evaluation for the system has been carried out. The findings of this study are: (1) it is technically feasible, utilizing commercially available hardware; (2) under utility ownership and operation, it will not be economically competitive with conventional alternatives for heating and cooling buildings (analysis contained in companion report under separate cover); (3) under utility ownership and operation, no restrictions have been identified that would prevent the project from proceeding; (4) under community ownership, preliminary analysis indicates that thermal energy produced by Trenton ICES will be approximately 12 percent less expensive than thermal energy produced by oil-fired boilers; and (5) a review and update of institutional analyses performed during Phase 2 has identified no factors that would preclude community ownership and operation of the Trenton ICES. The background data produced for the analysis of the Trenton ICES based on utility ownership and operation can, in large part, be used as the bases for a detailed analysis of community ownership.

  3. The use of phase sequence image sets to reconstruct the total volume occupied by a mobile lung tumor

    International Nuclear Information System (INIS)

    Gagne, Isabelle M.; Robinson, Don M.; Halperin, Ross; Roa, Wilson

    2005-01-01

    The use of phase sequence image (PSI) sets to reveal the total volume occupied by a mobile target is presented. Isocontrast composite clinical target volumes (CCTVs) may be constructed from PSI sets in order to reveal the total volume occupied by a mobile target during the course of its travel. The ability of the CCTV technique to properly account for target motion is demonstrated by comparison to contours of the true total volume occupied (TVO) for a number of experimental phantom geometries. Finally, using real patient data, the clinical utility of the CCTV technique to properly account for internal tumor motion while minimizing the volume of healthy lung tissue irradiated is assessed by comparison to the standard approach of applying safety margins. Results of the phantom study reveal that CCTV cross sections constructed at the 20% isocontrast level yield good agreement with the total cross sections (TXO) of mobile targets. These CCTVs conform well to the TVOs of the moving targets examined whereby the addition of small uniform margins ensures complete circumscription of the TVO with the inclusion of minimal amounts of surrounding external volumes. The CCTV technique is seen to be clearly superior to the common practice of the addition of safety margins to individual CTV contours in order to account for internal target motion. Margins required with the CCTV technique are eight to ten times smaller than those required with individual CTVs

  4. Volume changes of Vatnajökull ice cap, Iceland, due to surface mass balance, ice flow, and subglacial melting at geothermal areas

    DEFF Research Database (Denmark)

    Magnússon, Eyjólfur; Björnson, Helgi; Dall, Jørgen

    2005-01-01

    We present observed changes in the geometry of western Vatnajökull over a period of about ten years which are caused by the surface mass balance, ice flow (both during surges and quiescent periods), and basal melting due to geothermal and volcanic activity. Comparison of two digital elevation...

  5. TOTAL WOOD VOLUME ESTIMATION OF EUCALYPTUS SPECIES BY IMAGES OF LANDSAT SATELLITE

    Directory of Open Access Journals (Sweden)

    Elias Fernando Berra

    2012-12-01

    Full Text Available http://dx.doi.org/10.5902/198050987566Models relating spectral answers with biophysical parameters aim estimate variables, like wood volume, without the necessity of frequent field measurements. The objective was to develop models to estimate wood volume by Landsat 5 TM images, supported by regional forest inventory data. The image was geo-referenced and converted to spectral reflectance. After, the images-index NDVI (Normalized Difference Vegetation Index and SR (Simple Ratio was generated. The reflectance values of the bands (TM1, TM2, TM3 e TM4 and of the indices (NDVI and SR was related with the wood volume. The biggest correlation with volume was with the NDVI and SR indices. The variables selection was made by Stepwise method, which returned three regression models as significant to explain the variation in volume. Finally, the best fitted model was selected (volume = -830,95 + 46,05 (SR + 107,47 (TM2, which was applied on the Landsat image where the pixels had started to represent the estimated volume in m³/ha on the Eucalyptus sp. production units. This model, significant at 95% confidence level, explains 68% of the wood volume variation.

  6. Effect of total cementitious content on shear strength of high-volume fly ash concrete beams

    International Nuclear Information System (INIS)

    Arezoumandi, Mahdi; Volz, Jeffery S.; Ortega, Carlos A.; Myers, John J.

    2013-01-01

    Highlights: ► Existing design standards conservatively predicted the capacity of the HVFAC beams. ► In general, the HVFAC beams exceeded the code predicted shear strengths. ► The cementitious content did not have effect on the shear behavior of the HVFAC beams. - Abstract: The production of portland cement – the key ingredient in concrete – generates a significant amount of carbon dioxide. However, due to its incredible versatility, availability, and relatively low cost, concrete is the most consumed manmade material on the planet. One method of reducing concrete’s contribution to greenhouse gas emissions is the use of fly ash to replace a significant amount of the cement. This paper compares two experimental studies that were conducted to investigate the shear strength of full-scale beams constructed with high-volume fly ash concrete (HVFAC) – concrete with at least 50% of the cement replaced with fly ash. The primary difference between the two studies involved the amount of cementitious material, with one mix having a relatively high total cementitious content (502 kg/m 3 ) and the other mix having a relatively low total cementitious content (337 kg/m 3 ). Both mixes utilized a 70% replacement of portland cement with a Class C fly ash. Each of these experimental programs consisted of eight beams (six without shear reinforcing and two with shear reinforcing in the form of stirrups) with three different longitudinal reinforcement ratios. The beams were tested under a simply supported four-point loading condition. The experimental shear strengths of the beams were compared with both the shear provisions of selected standards (US, Australia, Canada, Europe, and Japan) and a shear database of conventional concrete (CC) specimens. Furthermore, statistical data analyses (both parametric and nonparametric) were performed to evaluate whether or not there is any statistically significant difference between the shear strength of both mixes. Results of these

  7. Effects of tidal volume and methacholine on low-frequency total respiratory impedance in dogs.

    Science.gov (United States)

    Lutchen, K R; Jackson, A C

    1990-05-01

    The frequency dependence of respiratory impedance (Zrs) from 0.125 to 4 Hz (Hantos et al., J. Appl. Physiol. 60: 123-132, 1986) may reflect inhomogeneous parallel time constants or the inherent viscoelastic properties of the respiratory tissues. However, studies on the lung alone or chest wall alone indicate that their impedance features are also dependent on the tidal volumes (VT) of the forced oscillations. The goals of this study were 1) to identify how total Zrs at lower frequencies measured with random noise (RN) compared with that measure with larger VT, 2) to identify how Zrs measured with RN is affected by bronchoconstriction, and 3) to identify the impact of using linear models for analyzing such data. We measured Zrs in six healthy dogs by use of a RN technique from 0.125 to 4 Hz or with a ventilator from 0.125 to 0.75 Hz with VT from 50 to 250 ml. Then methacholine was administered and the RN was repeated. Two linear models were fit to each separate set of data. Both models assume uniform airways leading to viscoelastic tissues. For healthy dogs, the respiratory resistance (Rrs) decreased with frequency, with most of the decrease occurring from 0.125 to 0.375 Hz. Significant VT dependence of Rrs was seen only at these lower frequencies, with Rrs higher as VT decreased. The respiratory compliance (Crs) was dependent on VT in a similar fashion at all frequencies, with Crs decreasing as VT decreased. Both linear models fit the data well at all VT, but the viscoelastic parameters of each model were very sensitive to VT. After methacholine, the minimum Rrs increased as did the total drop with frequency. Nevertheless the same models fit the data well, and both the airways and tissue parameters were altered after methacholine. We conclude that inferences based only on low-frequency Zrs data are problematic because of the effects of VT on such data (and subsequent linear modeling of it) and the apparent inability of such data to differentiate parallel

  8. Equal Pay for Equal Work: Medicare Procedure Volume and Reimbursement for Male and Female Surgeons Performing Total Knee and Total Hip Arthroplasty.

    Science.gov (United States)

    Holliday, Emma B; Brady, Christina; Pipkin, William C; Somerson, Jeremy S

    2018-02-21

    The observed sex gap in physician salary has been the topic of much recent debate in the United States, but it has not been well-described among orthopaedic surgeons. The objective of this study was to evaluate for sex differences in Medicare claim volume and reimbursement among orthopaedic surgeons. The Medicare Provider Utilization and Payment Public Use File was used to compare claim volume and reimbursement between female and male orthopaedic surgeons in 2013. Data were extracted for each billing code per orthopaedic surgeon in the year 2013 for total claims, surgical claims, total knee arthroplasty (TKA) claims, and total hip arthroplasty (THA) claims. A total of 20,546 orthopaedic surgeons who treated traditional Medicare patients were included in the initial analysis. Claim volume and reimbursement received were approximately twofold higher for all claims and more than threefold higher for surgical claims for male surgeons when compared with female surgeons (p 10 TKAs and THAs, respectively, in 2013 for Medicare patients and were included in the subset analyses. Although male surgeons performed a higher mean number of TKAs than female surgeons (mean and standard deviation, 37 ± 33 compared with 26 ± 17, respectively, p men and women for TKA or THA ($1,135 ± $228 compared with $1,137 ± $184 for TKA, respectively, p = 0.380; $1,049 ± $226 compared with $1,043 ± $266 for THA, respectively, p = 0.310). Female surgeons had a lower number of total claims and reimbursements compared with male surgeons. However, among surgeons who performed >10 THAs and TKAs, there were no sex differences in the mean reimbursement payment per surgeon. The number of women in orthopaedics is rising, and there is much interest in how their productivity and compensation compare with their male counterparts.

  9. Longitudinal changes in total brain volume in schizophrenia: relation to symptom severity, cognition and antipsychotic medication.

    Directory of Open Access Journals (Sweden)

    Juha Veijola

    Full Text Available Studies show evidence of longitudinal brain volume decreases in schizophrenia. We studied brain volume changes and their relation to symptom severity, level of function, cognition, and antipsychotic medication in participants with schizophrenia and control participants from a general population based birth cohort sample in a relatively long follow-up period of almost a decade. All members of the Northern Finland Birth Cohort 1966 with any psychotic disorder and a random sample not having psychosis were invited for a MRI brain scan, and clinical and cognitive assessment during 1999-2001 at the age of 33-35 years. A follow-up was conducted 9 years later during 2008-2010. Brain scans at both time points were obtained from 33 participants with schizophrenia and 71 control participants. Regression models were used to examine whether brain volume changes predicted clinical and cognitive changes over time, and whether antipsychotic medication predicted brain volume changes. The mean annual whole brain volume reduction was 0.69% in schizophrenia, and 0.49% in controls (p = 0.003, adjusted for gender, educational level, alcohol use and weight gain. The brain volume reduction in schizophrenia patients was found especially in the temporal lobe and periventricular area. Symptom severity, functioning level, and decline in cognition were not associated with brain volume reduction in schizophrenia. The amount of antipsychotic medication (dose years of equivalent to 100 mg daily chlorpromazine over the follow-up period predicted brain volume loss (p = 0.003 adjusted for symptom level, alcohol use and weight gain. In this population based sample, brain volume reduction continues in schizophrenia patients after the onset of illness, and antipsychotic medications may contribute to these reductions.

  10. Functional Response of Tumor Vasculature to PaCO2: Determination of Total and Microvascular Blood Volume by MRI

    Directory of Open Access Journals (Sweden)

    Scott D. Packard

    2003-07-01

    Full Text Available In order to identify differences in functional activity, we compared the reactivity of glioma vasculature and the native cerebral vasculature to both dilate and constrict in response to altered PaCO2. Gliomas were generated by unilateral implantation of U87MGdEGFR human glioma tumor cells into the striatum of adult female athymic rats. Relative changes in total and microvascular cerebral blood volume were determined by steady state contrast agent-enhanced magnetic resonance imaging for transitions from normocarbia to hypercarbia and hypocarbia. Although hypercarbia induced a significant increase in both total and microvascular blood volume in normal brain and glioma, reactivity of glioma vasculature was significantly blunted in comparison to normal striatum; glioma total CBV increased by 0.6±0.1%/mm Hg CO2 whereas normal striatum increased by 1.5±0.2%/mm Hg CO2, (P < .0001, group t-test. Reactivity of microvascular blood volume was also significantly blunted. In contrast, hypocarbia decreased both total and microvascular blood volumes more in glioma than in normal striatum. These results indicate that cerebral blood vessels derived by tumor-directed angiogenesis do retain reactivity to CO2. Furthermore, reduced reactivity of tumor vessels to a single physiological perturbation, such as hypercarbia, should not be construed as a generalized reduction of functional activity of the tumor vascular bed.

  11. Endmembers of Ice Shelf Melt

    Science.gov (United States)

    Boghosian, A.; Child, S. F.; Kingslake, J.; Tedesco, M.; Bell, R. E.; Alexandrov, O.; McMichael, S.

    2017-12-01

    Studies of surface melt on ice shelves have defined a spectrum of meltwater behavior. On one end the storage of meltwater in persistent surface ponds can trigger ice shelf collapse as in the 2002 event leading to the disintegration of the Larsen B Ice Shelf. On the other, meltwater export by rivers can stabilize an ice shelf as was recently shown on the Nansen Ice Shelf. We explore this dichotomy by quantifying the partitioning between stored and transported water on two glaciers adjacent to floating ice shelves, Nimrod (Antarctica) and Peterman (Greenland). We analyze optical satellite imagery (LANDSAT, WorldView), airborne imagery (Operation IceBridge, Trimetrogon Aerial Phototography), satellite radar (Sentinel-1), and digital elevation models (DEMs) to categorize surface meltwater fate and map the evolution of ice shelf hydrology and topographic features through time. On the floating Peterman Glacier tongue a sizable river exports water to the ocean. The surface hydrology of Nimrod Glacier, geometrically similar to Peterman but with ten times shallower surface slope, is dominated by storage in surface lakes. In contrast, the Nansen has the same surface slope as Nimrod but transports water through surface rivers. Slope alone is not the sole control on ice shelf hydrology. It is essential to track the storage and transport volumes for each of these systems. To estimate water storage and transport we analyze high resolution (40 cm - 2 m) modern and historical DEMs. We produce historical (1957 onwards) DEMs with structure-from-motion photogrammetry. The DEMs are used to constrain water storage potential estimates of observed basins and water routing/transport potential. We quantify the total volume of water stored seasonally and interannually. We use the normalize difference water index to map meltwater extent, and estimate lake water depth from optical data. We also consider the role of stored water in subsurface aquifers in recharging surface water after

  12. Improved ice loss estimate of the northwestern Greenland ice sheet

    DEFF Research Database (Denmark)

    Kjeldsen, Kristian Kjellerup; Khan, Shfaqat Abbas; Wahr, J.

    2013-01-01

    We estimate ice volume change rates in the northwest Greenland drainage basin during 2003–2009 using Ice, Cloud and land Elevation Satellite (ICESat) laser altimeter data. Elevation changes are often reported to be largest near the frontal portion of outlet glaciers. To improve the volume change...... estimate, we supplement the ICESat data with altimeter surveys from NASA's Airborne Topographic Mapper from 2002 to 2010 and NASA's Land, Vegetation and Ice Sensor from 2010. The Airborne data are mainly concentrated along the ice margin and thus have a significant impact on the estimate of the volume...... change. Our results show that adding Airborne Topographic Mapper and Land, Vegetation and Ice Sensor data to the ICESat data increases the catchment-wide estimate of ice volume loss by 11%, mainly due to an improved volume loss estimate along the ice sheet margin. Furthermore, our results show...

  13. Sea Ice Ecosystems

    Science.gov (United States)

    Arrigo, Kevin R.

    2014-01-01

    Polar sea ice is one of the largest ecosystems on Earth. The liquid brine fraction of the ice matrix is home to a diverse array of organisms, ranging from tiny archaea to larger fish and invertebrates. These organisms can tolerate high brine salinity and low temperature but do best when conditions are milder. Thriving ice algal communities, generally dominated by diatoms, live at the ice/water interface and in recently flooded surface and interior layers, especially during spring, when temperatures begin to rise. Although protists dominate the sea ice biomass, heterotrophic bacteria are also abundant. The sea ice ecosystem provides food for a host of animals, with crustaceans being the most conspicuous. Uneaten organic matter from the ice sinks through the water column and feeds benthic ecosystems. As sea ice extent declines, ice algae likely contribute a shrinking fraction of the total amount of organic matter produced in polar waters.

  14. Risk factors for radiation pneumonitis after stereotactic radiation therapy for lung tumours: clinical usefulness of the planning target volume to total lung volume ratio.

    Science.gov (United States)

    Ueyama, Tomoko; Arimura, Takeshi; Takumi, Koji; Nakamura, Fumihiko; Higashi, Ryutaro; Ito, Soichiro; Fukukura, Yoshihiko; Umanodan, Tomokazu; Nakajo, Masanori; Koriyama, Chihaya; Yoshiura, Takashi

    2018-06-01

    To identify risk factors for symptomatic radiation pneumonitis (RP) after stereotactic radiation therapy (SRT) for lung tumours. We retrospectively evaluated 68 lung tumours in 63 patients treated with SRT between 2011 and 2015. RP was graded according to the National Cancer Institute-Common Terminology Criteria for Adverse Events version 4.0. SRT was delivered at 7.0-12.0 Gy per each fraction, once daily, to a total of 48-64 Gy (median, 50 Gy). Univariate analysis was performed to assess patient- and treatment-related factors, including age, sex, smoking index (SI), pulmonary function, tumour location, serum Krebs von den Lungen-6 value (KL-6), dose-volume metrics (V5, V10, V20, V30, V40 and VS5), homogeneity index of the planning target volume (PTV), PTV dose, mean lung dose (MLD), contralateral MLD and V2, PTV volume, lung volume and the PTV/lung volume ratio (PTV/Lung). Performance of PTV/Lung in predicting symptomatic RP was also analysed using receiver operating characteristic (ROC) analysis. The median follow-up period was 21 months. 10 of 63 patients (15.9%) developed symptomatic RP after SRT. On univariate analysis, V10, V20, PTV volume and PTV/Lung were significantly associated with occurrence of RP  ≥Grade 2. ROC curves indicated that symptomatic RP could be predicted using PTV/Lung [area under curve (AUC): 0.88, confidence interval (CI: 0.78-0.95), cut-off value: 1.09, sensitivity: 90.0% and specificity: 72.4%]. PTV/Lung is a good predictor of symptomatic RP after SRT. Advances in knowledge: The cases with high PTV/Lung should be carefully monitored with caution for the occurrence of RP after SRT.

  15. SU-E-J-249: Correlation of Mean Lung Ventilation Value with Ratio of Total Lung Volumes

    International Nuclear Information System (INIS)

    Yu, N; Qu, H; Xia, P

    2014-01-01

    Purpose: Lung ventilation function measured from 4D-CT and from breathing correlated CT images is a novel concept to incorporate the lung physiologic function into treatment planning of radiotherapy. The calculated ventilation functions may vary from different breathing patterns, affecting evaluation of the treatment plans. The purpose of this study is to correlate the mean lung ventilation value with the ratio of the total lung volumes obtained from the relevant CTs. Methods: A ventilation map was calculated from the variations of voxel-to-voxel CT densities from two breathing phases from either 4D-CT or breathing correlated CTs. An open source image registration tool of Plastimatch was used to deform the inhale phase images to the exhale phase images. To calculate the ventilation map inside lung, the whole lung was delineated and the tissue outside the lung was masked out. With a software tool developed in house, the 3D ventilation map was then converted in the DICOM format associated with the planning CT images. The ventilation map was analyzed on a clinical workstation. To correlate ventilation map thus calculated with lung volume change, the total lung volume change was compared the mean ventilation from our method. Results: Twenty two patients who underwent stereotactic body irradiation for lung cancer was selected for this retrospective study. For this group of patients, the ratio of lung volumes for the inhale (Vin ) and exhale phase (Vex ) was shown to be linearly related to the mean of the local ventilation (Vent), Vin/Vex=1.+0.49*Vent (R2=0.93, p<0.01). Conclusion: The total lung volume change is highly correlated with the mean of local ventilation. The mean of local ventilation may be useful to assess the patient's lung capacity

  16. First combined total reflection X-ray fluorescence and grazing incidence X-ray absorption spectroscopy characterization of aeolian dust archived in Antarctica and Alpine deep ice cores

    Energy Technology Data Exchange (ETDEWEB)

    Cibin, G. [Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxon OX110DE (United Kingdom); IMONT/EIM, Ente Italiano della Montagna, P.za dei Caprettari 70, 00176 Roma (Italy); Universita' degli Studi di Roma Tre, Dipartimento di Scienze Geologiche, L.go S. Leonardo Murialdo 1, 00146 Roma (Italy)], E-mail: giannantonio.cibin@diamond.ac.uk; Marcelli, A. [INFN - Laboratori Nazionali di Frascati, P.O. Box 13, 00044 Frascati (Roma) (Italy); Maggi, V. [Universita degli Studi di Milano-Bicocca, Dipartimento di Scienze dell' Ambiente e del Territorio, Piazza della Scienza 1, 20126 Milano (Italy); Sala, M. [Universita degli Studi di Milano-Bicocca, Dipartimento di Scienze dell' Ambiente e del Territorio, Piazza della Scienza 1, 20126 Milano (Italy); Universita degli Studi di Milano, Dipartimento di Scienze della Terra ' A. Desio' , Sez. Mineralogia, Via Mangiagalli 34, 20133 Milano (Italy); Marino, F.; Delmonte, B. [Universita degli Studi di Milano-Bicocca, Dipartimento di Scienze dell' Ambiente e del Territorio, Piazza della Scienza 1, 20126 Milano (Italy); Albani, S. [Universita degli Studi di Milano-Bicocca, Dipartimento di Scienze dell' Ambiente e del Territorio, Piazza della Scienza 1, 20126 Milano (Italy); Universita degli Studi di Siena, Dottorato in Scienze Polari, via Laterina 8, 53100 Siena (Italy); Pignotti, S. [IMONT/EIM, Ente Italiano della Montagna, P.za dei Caprettari 70, 00176 Roma (Italy)

    2008-12-15

    Aeolian mineral dust archived in polar and mid latitude ice cores represents a precious proxy for assessing environmental and climatic variations at different timescales. In this respect, the identification of dust mineralogy plays a key role. In this work we performed the first preliminary X-ray absorption spectroscopy (XAS) experiments on mineral dust particles extracted from Antarctic and from Alpine firn cores using grazing incidence geometry at the Fe K-edge. A dedicated high vacuum experimental chamber was set up for normal-incidence and total-reflection X-Ray Fluorescence and Absorption Spectroscopy analyses on minor amounts of mineral materials at the Stanford Synchrotron Radiation Laboratory. Results show that this experimental technique and protocol allows recognizing iron inclusion mineral fraction on insoluble dust in the 1-10 {mu}g range.

  17. First combined total reflection X-ray fluorescence and grazing incidence X-ray absorption spectroscopy characterization of aeolian dust archived in Antarctica and Alpine deep ice cores

    International Nuclear Information System (INIS)

    Cibin, G.; Marcelli, A.; Maggi, V.; Sala, M.; Marino, F.; Delmonte, B.; Albani, S.; Pignotti, S.

    2008-01-01

    Aeolian mineral dust archived in polar and mid latitude ice cores represents a precious proxy for assessing environmental and climatic variations at different timescales. In this respect, the identification of dust mineralogy plays a key role. In this work we performed the first preliminary X-ray absorption spectroscopy (XAS) experiments on mineral dust particles extracted from Antarctic and from Alpine firn cores using grazing incidence geometry at the Fe K-edge. A dedicated high vacuum experimental chamber was set up for normal-incidence and total-reflection X-Ray Fluorescence and Absorption Spectroscopy analyses on minor amounts of mineral materials at the Stanford Synchrotron Radiation Laboratory. Results show that this experimental technique and protocol allows recognizing iron inclusion mineral fraction on insoluble dust in the 1-10 μg range

  18. Volume-dependent hemodynamic effects of blood collection in canine donors - evaluation of 13% and 15% of total blood volume depletion

    Directory of Open Access Journals (Sweden)

    RUI R.F. FERREIRA

    2015-03-01

    Full Text Available Background: There is no consensus regarding the blood volume that could be safely donated by dogs, ranging from 11 to 25% of its total blood volume (TBV. No previous studies evaluated sedated donors.Aim: To evaluate the hemodynamic effects of blood collection from sedated and non-sedated dogs and to understand if such effects were volume-dependent.Materials and Methods: Fifty three donations of 13% of TBV and 20 donations of 15% TBV were performed in dogs sedated with diazepam and ketamine. Additionally, a total of 30 collections of 13% TBV and 20 collections of 15% TBV were performed in non-sedated dogs. Non-invasive arterial blood pressures and pulse rates were registered before and 15 min after donation. Results: Post-donation pulse rates increased significantly in both sedated groups, with higher differences in the 15% TBV collections. Systolic arterial pressures decreased significantly in these groups, while diastolic pressures increased significantly in 13% TBV donations. Non-sedated groups revealed a slight, but significant, SBP decrease. No clinical signs related to donations were registered.Conclusion: These results suggest that the collection of 15% TBV in sedated donors induces hemodynamic variations that may compromise the harmlessness of the procedure, while it seems to be a safe procedure in non-sedated dogs.

  19. Total Stem and Merchantable Volume Equations of Norway Spruce (Picea abies (L.) Karst.) Growing on Former Farmland in Sweden

    OpenAIRE

    Johansson, Tord

    2014-01-01

    An equation was constructed to estimate the stem volume of Norway spruce (Picea abies (L.) Karst.) in 145 stands growing on former farmland in Sweden (Latitude 56-63 degrees N). The mean total age was 40 +/- 13 (range 17-91) years, the mean diameter at breast height (ob) was 15 +/- 4 (range 5-27) cm and the mean density was 1621 +/- 902 (range 100-7600) stems ha(-1). The equation which fits the data best used the diameter at breast height and total stem height as predictive variables. Merchan...

  20. Modelling snow ice and superimposed ice on landfast sea ice in Kongsfjorden, Svalbard

    Directory of Open Access Journals (Sweden)

    Caixin Wang

    2015-08-01

    Full Text Available Snow ice and superimposed ice formation on landfast sea ice in a Svalbard fjord, Kongsfjorden, was investigated with a high-resolution thermodynamic snow and sea-ice model, applying meteorological weather station data as external forcing. The model shows that sea-ice formation occurs both at the ice bottom and at the snow/ice interface. Modelling results indicated that the total snow ice and superimposed ice, which formed at the snow/ice interface, was about 14 cm during the simulation period, accounting for about 15% of the total ice mass and 35% of the total ice growth. Introducing a time-dependent snow density improved the modelled results, and a time-dependent oceanic heat flux parameterization yielded reasonable ice growth at the ice bottom. Model results suggest that weather conditions, in particular air temperature and precipitation, as well as snow thermal properties and surface albedo are the most critical factors for the development of snow ice and superimposed ice in Kongsfjorden. While both warming air and higher precipitation led to increased snow ice and superimposed ice forming in Kongsfjorden in the model runs, the processes were more sensitive to precipitation than to air temperature.

  1. Increased epicardial fat volume quantified by 64-multidetector computed tomography is associated with coronary atherosclerosis and totally occlusive lesions

    International Nuclear Information System (INIS)

    Ueno, Koji; Anzai, Toshihisa; Jinzaki, Masahiro

    2009-01-01

    The relationship between the epicardial fat volume measured by 64-slice multidetector computed tomography (MDCT) and the extension and severity of coronary atherosclerosis was investigated. Both MDCT and conventional coronary angiography (CAG) were performed in 71 consecutive patients who presented with effort angina. The volume of epicardial adipose tissue (EAT) was measured by MDCT. The severity of coronary atherosclerosis was assessed by evaluating the extension of coronary plaques in 790 segments using MDCT data, and the percentage diameter stenosis in 995 segments using CAG data. The estimated volume of EAT indexed by body surface area was defined as VEAT. Increased VEAT was associated with advanced age, male sex, degree of metabolic alterations, a history of acute coronary syndrome (ACS) and the presence of total occlusions, and showed positive correlation with the stenosis score r=0.28, P=0.02) and the atheromatosis score (r=0.67, P 3 /m 2 ) to be the strongest independent determinant of the presence of total occlusions odds ratio 4.64. P=0.02). VEAT correlates with the degree of metabolic alterations and coronary atheromatosis. Excessive accumulation of EAT might contribute to the development of ACS and coronary total occlusions. (author)

  2. REGULARITIES OF CONGELATION ICE DEVELOPMENT IN SUBGLACIAL LAKE VOSTOK

    Directory of Open Access Journals (Sweden)

    V. Ya. Lipenkov

    2012-01-01

    Full Text Available Petrographic studies performed on the continuous basis along the two ice cores obtained from holes 5G-1 and 5G-2 at Vostok Station has allowed to characterize with great details the evolution of the ice texture and fabric in the 232-m thick stratum of accreted ice formed from theLakeVostokwater. Conventionally the whole thickness of accreted ice is divided into two strata: lake ice 1 and lake ice 2. Lake ice 1 (3537–3618 m, formed in the sallow strait50 kmupstream of Vostok, is characterized by presence of disseminated mineral inclusions of Lake Vostok sediments, as well as of «water pockets» that represent frozen water inclusions trapped during the ice accretion. The latter constitute less than 1% of the total ice volume, their mean size is about0.5 cm. Gases trapped by «water pockets» during ice formation transform into crystalline inclusions of mixed gas hydrates. Accretion of lake ice 2 (3618–3769 m proceeds in the deep part of the lake at a very small rate that does not assume trapping of liquid water inclusions and gases.Both strata of accreted ice are formed by orthotropic crystal growth from pure water. The main tendency in the evolution of accreted ice texture is growth of the mean crystal size with depth as the lake ice becomes younger towards the ice-water interface. The high-amplitude variations of crystal size and orientation observed around this general trend are shown to be linked with temporal and spatial variability of the supercooled melt-water flux from the northern part of the lake towards the ice formation site. The presence of supercooled water at the crystallization front supports persistent preferable growth of ice crystals with sub-horizontally oriented c-axes. The lack of supercooled water in turn support persistent growth of ice crystals with vertical or inclined with respect to the crystallization front c-axis orientation. It means that each of these preferred fabric orientations could serve as an indicator of

  3. Association of Automatically Quantified Total Blood Volume after Aneurysmal Subarachnoid Hemorrhage with Delayed Cerebral Ischemia

    NARCIS (Netherlands)

    Zijlstra, I. A.; Gathier, C. S.; Boers, A. M.; Marquering, H. A.; Slooter, A. J.; Velthuis, B. K.; Coert, B. A.; Verbaan, D.; van den Berg, R.; Rinkel, G. J.; Majoie, C. B.

    2016-01-01

    The total amount of extravasated blood after aneurysmal subarachnoid hemorrhage, assessed with semiquantitative methods such as the modified Fisher and Hijdra scales, is known to be a predictor of delayed cerebral ischemia. However, prediction rates of delayed cerebral ischemia are moderate, which

  4. Paid to Perform: Aligning Total Military Compensation With Talent Management. Volume 8

    Science.gov (United States)

    2015-06-01

    study upon which a wider compensation model can be built, we propose a system that thoughtfully integrates rede - signed basic pays and pensions...Taken together, these basic pay and pension rede - sign components will create a far more cost-effective total compensation system than the one

  5. Institutional applications of solar total-energy systems. Draft final report. Volume 2. Appendixes

    Energy Technology Data Exchange (ETDEWEB)

    None

    1978-07-01

    The appendices present the analytical basis for the analysis of solar total energy (STE) systems. A regional-climate model and a building-load requirements model are developed, along with fuel-price scenarios. Life-cycle costs are compared for conventional-utility, total energy, and STE systems. Thermal STE system design trade-offs are performed and thermal STE system performance is determined. The sensitivity of STE competitiveness to fuel prices is examined. The selection of the photovoltaic array is briefly discussed. The institutional-sector decision processes are analyzed. Hypothetical regional back-up rates and electrical-energy costs are calculated. The algorithms and equations used in operating the market model are given, and a general methodology is developed for projecting the size of the market for STE systems and applied to each of 8 institutional subsectors. (LEW)

  6. Ross Ice Shelf, Antarctic Ice and Clouds

    Science.gov (United States)

    1991-01-01

    In this view of Antarctic ice and clouds, (56.5S, 152.0W), the Ross Ice Shelf of Antarctica is almost totally clear, showing stress cracks in the ice surface caused by wind and tidal drift. Clouds on the eastern edge of the picture are associated with an Antarctic cyclone. Winds stirred up these storms have been known to reach hurricane force.

  7. Allometric relations of total volumes of prolactin cells and corticotropic cells to body length in the annual cyprinodont Cynolebias whitei: effects of environmental salinity, stress and ageing

    NARCIS (Netherlands)

    Ruijter, J. M.; Wendelaar Bonga, S. E.

    1987-01-01

    An analysis of the allometric relations of the total volumes occupied by prolactin (PRL) and corticotropic (ACTH) cells (PRL volume and ACTH volume, respectively) to body length and a study of the immunocytochemical staining intensity of PRL and ACTH cells were used to determine the differences in

  8. The state of the Greenland Ice Sheet

    DEFF Research Database (Denmark)

    Simonsen, Sebastian Bjerregaard

    Firn is defined as snow that has survived a melt season and provides the link between the high-frequency variability of the atmosphere to the ”slower” reacting ice sheet.In this thesis, firn is described by a theoretical and statistical approach to accommodate the variability in observed firn...... compaction on ice sheet scales. The modeling objectives are multiple and aim at estimating the contribution from the firn to the observed volume change of the GrIS and to the diffusion of stable water isotopes. The firn modeling then provides crucial information on total mass balance of the Gr......IS and the paleo-temperature reconstructions retrieved from ice cores.The dynamical firn model developed in this thesis explains13 % of the observed volume change of the GrIS from 2003-2008, without contributing to the global sea-level rise. This emphasizes the need for well constraint firn-compaction models. Here...

  9. Evaluation of Productivity of Zymotis Solid-State Bioreactor Based on Total Reactor Volume

    Directory of Open Access Journals (Sweden)

    Oscar F. von Meien

    2002-01-01

    Full Text Available In this work a method of analyzing the performance of solid-state fermentation bioreactors is described. The method is used to investigate the optimal value for the spacing between the cooling plates of the Zymotis bioreactor, using simulated fermentation data supplied by a mathematical model. The Zymotis bioreactor has good potential for those solid-state fermentation processes in which the substrate bed must remain static. The current work addresses two design parameters introduced by the presence of the internal heat transfer plates: the width of the heat transfer plate, which is governed by the amount of heat to be removed and the pressure drop of the cooling water, and the spacing between these heat transfer plates. In order to analyze the performance of the bioreactor a productivity term is introduced that takes into account the volume occupied within the bioreactor by the heat transfer plates. As part of this analysis, it is shown that, for logistic growth kinetics, the time at which the biomass reaches 90 % of its maximum possible value is a good estimate of the optimum harvesting time for maximizing productivity. Application of the productivity analysis to the simulated fermentation results suggests that, with typical fast growing fungi ( = 0.324 h–1, the optimal spacing between heat transfer plates is of the order of 6 cm. The general applicability of this approach to evaluate the productivity of solid-state bioreactors is demonstrated.

  10. Acquisition of Ice Thickness and Ice Surface Characteristics in the Seasonal Ice Zone by CULPIS-X during the US Coast Guard’s Arctic Domain Awareness Program

    Science.gov (United States)

    2014-09-30

    OBJECTIVES • What is the volume of sea ice in the Beaufort Sea Seasonal Ice Zone (SIZ) and how does this evolve during summer as the ice edge...retreats? Recent observations suggest that the remaining ice in the Beaufort Sea is younger and thinner in recent years in part because even the oldest...surrounding ice . Recent analyses have indicated that ponds on thinner ice are often darker, accelerating the ice - albedo feedback over thin ice in summer

  11. Maximized liquid radwaste volume reduction through a total integrated process: A new technology success story

    International Nuclear Information System (INIS)

    Rae, G.A.

    1996-01-01

    A fundamental nuclear industry goal is the minimization of the generation of radioactive waste. This goal has been dramatically reinforced over the past few years due to the spiraling increased costs of both commercial and DOE disposal. To assist in meeting these goals and reducing the industry's costs, NUKEM initiated a new technology program to maximize the reduction of liquid radwaste through the use of a systematic approach or TIPS (Total Integrated Process System). This concept evaluates the total life cycle of various technologies in a combination that results in the final waste form being minimized to the pure solids content of the waste stream. Additionally, it allows for a final waste form that maximizes the utilization of the waste package and is conditioned to be readily acceptable to additional processing to meet new waste form requirements at future disposal sites, should interim storage of the waste be required. The TIPS, although first introduced at commercial facilities, has broad applications for DOE's liquid waste streams

  12. Total Stem and Merchantable Volume Equations of Norway Spruce (Picea abies (L. Karst. Growing on Former Farmland in Sweden

    Directory of Open Access Journals (Sweden)

    Tord Johansson

    2014-08-01

    Full Text Available An equation was constructed to estimate the stem volume of Norway spruce (Picea abies (L. Karst. in 145 stands growing on former farmland in Sweden (Latitude 56–63° N. The mean total age was 40 ± 13 (range 17–91 years, the mean diameter at breast height (ob was 15 ± 4 (range 5–27 cm and the mean density was 1621 ± 902 (range 100–7600 stems ha−1. The equation which fits the data best used the diameter at breast height and total stem height as predictive variables. Merchantable volume equations for the estimation of commercial volume for any top diameter and bole length were developed. Soil types in the stands were sediments (coarse sand, fine sand and silt and heavy, medium and light clay, tills (sandy, fine sandy and silty and peat. The standing volume was calculated; the mean was 253 ± 103 (range 26–507 m3 ha−1 with a MAI (mean annual increment of 6.9±3.5 (range 1.3–16.7 m3 ha−1 year−1. There were statistically significant differences between MAI and coarse sand, sand and silt, light clay, peat and silty till soils. Spruce stands growing on silty tills had the lowest MAI (4.94 ± 2.27 m3 ha−1 year−1 and light clay, fine sand and silt and peat the highest (7.62 ± 4.24, 7.46 ± 3.33 and 8.67 ± 2.83 m3 ha−1 year−1.

  13. Optimization of total arc degree for stereotactic radiotherapy by using integral biologically effective dose and irradiated volume

    International Nuclear Information System (INIS)

    Lim, Do Hoon; Kim, Dae Yong; Lee, Myung Za; Chun, Ha Chung

    2001-01-01

    To find the optimal values of total arc degree to protect the normal brain tissue from high dose radiation in stereotactic radiotherapy planning. With Xknife-3 planning system and 4 MV linear accelerator, the authors planned under various values of parameters. One isocenter, 12, 20, 30, 40, 50, and 60 mm of collimator diameters, 100 deg, 200 deg, 300 deg, 400 deg, 500 deg, 600 deg, of total arc degrees, and 30 deg or 45 deg of arc intervals were used. After the completion of planning, the plans were compared each other using V 50 (the volume of normal brain that is delivered high dose radiation) and integral biologically effective dose. At 30 deg of arc interval, the values of V 50 had the decreased pattern with the increase of total arc degree in any collimator diameter. At 45 deg arc interval, up to 400 deg of total arc degree, the values of V 50 decreased with the increase of total arc degree, but at 500 deg and 600 deg of total arc degrees, the values increased. At 30 deg of arc interval, integral biologically effective dose showed the decreased pattern with the increase of total arc degree in any collimator diameter. At 45 deg arc interval with less than 40 mm collimator diameter, the integral biologically effective dose decreased with the increase of total arc degree, but with 50 and 60 mm of collimator diameters, up to 400 deg of total arc degree, integral biologically effective dose decreased with the increase of total arc degree, but at 500 deg and 600 deg of total arc degrees, the values increased. In the stereotactic radiotherapy planning for brain lesions, planning with 400 deg of total arc degree is optimal. Especially, when the larger collimator more than 50 mm diameter should be used, the uses of 500 deg and 600 deg of total arc degrees make the increase of V 50 and integral biologically effective dose, Therefore stereotactic radiotherapy planning using 400 deg of total arc degree can increase the therapeutic ratio and produce the effective outcome

  14. Viability Assessment of a Repository at Yucca Mountain. Volume 3: Total System Performance Assessment

    Energy Technology Data Exchange (ETDEWEB)

    None

    1998-12-01

    This volume reports the development of TSPA for the VA. This first section defines the general process involved in developing any TSPA, it describes the overall TSPA process as implemented by programs in the US and elsewhere in the world, and discusses the acceptability of TSPA as a process or tool for analyzing a nuclear waste repository system. Section 2 discusses the more specific use of the TSPA process for the TSPA-VA for Yucca Mountain, including goals, approach, and methods. It also includes a very brief synopsis of TSPA-VA results. Section 3 briefly discusses each of the component models that comprise the TSPA-VA. Each TSPA component model represents a discrete set of processes. The TSPA-VA components are: unsaturated zone flow, thermal hydrology, near- field geochemical environment, waste package degradation, waste form alteration and mobilization, unsaturated zone transport, saturated zone flow and transport, and biosphere. For each of these components, this section introduces the conceptualization of each individual process, describes the data sources, and discusses model parameter development and computer methods used to simulate each component. Section 4 explains the mechanics of how the individual TSPA components were combined into a ''base case'' and then provides the ''expected value'' results of a deterministic base case analysis. Section 4 also contains a description of the probabilistic analyses and results that help determine the relative importance of the various TSPA components and the data used to describe the components. Section 5 addresses sensitivity studies run for each of the TSPA components to understand how uncertainty in various parameters within a component change the TSPA results. Section 6 presents the findings of the sensitivity studies run on the various components in Section 5, and prioritizes the findings of the entire set of uncertainty and sensitivity studies of the components relative

  15. Ice Sheets & Ice Cores

    DEFF Research Database (Denmark)

    Mikkelsen, Troels Bøgeholm

    Since the discovery of the Ice Ages it has been evident that Earth’s climate is liable to undergo dramatic changes. The previous climatic period known as the Last Glacial saw large oscillations in the extent of ice sheets covering the Northern hemisphere. Understanding these oscillations known....... The first part concerns time series analysis of ice core data obtained from the Greenland Ice Sheet. We analyze parts of the time series where DO-events occur using the so-called transfer operator and compare the results with time series from a simple model capable of switching by either undergoing...

  16. Total-system performance assessment for Yucca Mountain - SNL second iteration (TSPA-1993); Volume 1

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, M.L.; Gauthier, J.H.; Barnard, R.W.; Barr, G.E.; Dockery, H.A.; Dunn, E.; Eaton, R.R.; Guerin, D.C.; Lu, N.; Martinez, M.J. [and others

    1994-04-01

    Sandia National Laboratories has completed the second iteration of the periodic total-system performance assessments (TSPA-93) for the Yucca Mountain Site Characterization Project (YMP). These analyses estimate the future behavior of a potential repository for high-level nuclear waste at the Yucca Mountain, Nevada, site under consideration by the Department of Energy. TSPA-93 builds upon previous efforts by emphasizing YMP concerns relating to site characterization, design, and regulatory compliance. Scenarios describing expected conditions (aqueous and gaseous transport of contaminants) and low-probability events (human-intrusion drilling and volcanic intrusion) are modeled. The hydrologic processes modeled include estimates of the perturbations to ambient conditions caused by heating of the repository resulting from radioactive decay of the waste. Hydrologic parameters and parameter probability distributions have been derived from available site data. Possible future climate changes are modeled by considering two separate groundwater infiltration conditions: {open_quotes}wet{close_quotes} with a mean flux of 10 mm/yr, and {open_quotes}dry{close_quotes} with a mean flux of 0.5 mm/yr. Two alternative waste-package designs and two alternative repository areal thermal power densities are investigated. One waste package is a thin-wall container emplaced in a vertical borehole, and the second is a container designed with corrosion-resistant and corrosion-allowance walls emplaced horizontally in the drift. Thermal power loadings of 57 kW/acre (the loading specified in the original repository conceptual design) and 114 kW/acre (a loading chosen to investigate effects of a {open_quotes}hot repository{close_quotes}) are considered. TSPA-93 incorporates significant new detailed process modeling, including two- and three-dimensional modeling of thermal effects, groundwater flow in the saturated-zone aquifers, and gas flow in the unsaturated zone.

  17. Total-system performance assessment for Yucca Mountain - SNL second iteration (TSPA-1993); Volume 2

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, M.L.; Barnard, R.W.; Barr, G.E.; Dockery, H.A.; Dunn, E.; Eaton, R.R.; Martinez, M.J. [Sandia National Labs., Albuquerque, NM (United States); Gauthier, J.H.; Guerin, D.C.; Lu, N. [and others

    1994-04-01

    Sandia National Laboratories has completed the second iteration of the periodic total-system performance assessments (TSPA-93) for the Yucca Mountain Site Characterization Project (YMP). These analyses estimate the future behavior of a potential repository for high-level nuclear waste at the Yucca Mountain, Nevada, site under consideration by the Department of Energy. TSPA-93 builds upon previous efforts by emphasizing YMP concerns relating to site characterization, design, and regulatory compliance. Scenarios describing expected conditions (aqueous and gaseous transport of contaminants) and low-probability events (human-intrusion drilling and volcanic intrusion) are modeled. The hydrologic processes modeled include estimates of the perturbations to ambient conditions caused by heating of the repository resulting from radioactive decay of the waste. Hydrologic parameters and parameter probability distributions have been derived from available site data. Possible future climate changes are modeled by considering two separate groundwater infiltration conditions: {open_quotes}wet{close_quotes} with a mean flux of 10 mm/yr, and {open_quotes}dry{close_quotes} with a mean flux of 0.5 mm/yr. Two alternative waste-package designs and two alternative repository areal thermal power densities are investigated. One waste package is a thin-wall container emplaced in a vertical borehole, and the second is a container designed with corrosion-resistant and corrosion-allowance walls emplaced horizontally in the drift. Thermal power loadings of 57 kW/acre (the loading specified in the original repository conceptual design) and 114 kW/acre (a loading chosen to investigate effects of a {open_quotes}hot repository{close_quotes}) are considered. TSPA-93 incorporates significant new detailed process modeling, including two- and three-dimensional modeling of thermal effects, groundwater flow in the saturated-zone aquifers, and gas flow in the unsaturated zone.

  18. Retrieval of sea ice thickness during Arctic summer using melt pond color

    Science.gov (United States)

    Istomina, L.; Nicolaus, M.; Heygster, G.

    2016-12-01

    The thickness of sea ice is an important climatic variable. Together with the ice concentration, it defines the total sea ice volume, is linked within the climatic feedback mechanisms and affects the Arctic energy balance greatly. During Arctic summer, the sea ice cover changes rapidly, which includes the presence of melt ponds, as well as reduction of ice albedo and ice thickness. Currently available remote sensing retrievals of sea ice thickness utilize data from altimeter, microwave, thermal infrared sensors and their combinations. All of these methods are compromised in summer in the presence of melt. This only leaves in situ and airborne sea ice thickness data available in summer. At the same time, data of greater coverage is needed for assimilation in global circulation models and correct estimation of ice mass balance.This study presents a new approach to estimate sea ice thickness in summer in the presence of melt ponds. Analysis of field data obtained during the RV "Polarstern" cruise ARK27/3 (August - October 2012) has shown a clear connection of ice thickness under melt ponds to their measured spectral albedo and to melt pond color in the hue-saturation-luminance color space from field photographs. An empirical function is derived from the HSL values and applied to aerial imagery obtained during various airborne campaigns. Comparison to in situ ice thickness shows a good correspondence to the ice thickness value retrieved in the melt ponds. A similar retrieval is developed for satellite spectral bands using the connection of the measured pond spectral albedo to the ice thickness within the melt ponds. Correction of the retrieved ice thickness in ponds to derive total thickness of sea ice is discussed. Case studies and application to very high resolution optical data are presented, as well as a concept to transfer the method to satellite data of lower spatial resolution where melt ponds become subpixel features.

  19. Improved ice loss estimate of the northwestern Greenland ice sheet

    NARCIS (Netherlands)

    Kjeldsen, K.K.; Khan, S.A.; van den Broeke, M.R.; van Angelen, J.H.

    2013-01-01

    We estimate ice volume change rates in the northwest Greenland drainage basin during 2003–2009 using Ice, Cloud and land Elevation Satellite (ICESat) laser altimeter data. Elevation changes are often reported to be largest near the frontal portion of outlet glaciers. To improve the volume change

  20. Ice, Ice, Baby!

    Science.gov (United States)

    Hamilton, C.

    2008-12-01

    The Center for Remote Sensing of Ice Sheets (CReSIS) has developed an outreach program based on hands-on activities called "Ice, Ice, Baby". These lessons are designed to teach the science principles of displacement, forces of motion, density, and states of matter. These properties are easily taught through the interesting topics of glaciers, icebergs, and sea level rise in K-8 classrooms. The activities are fun, engaging, and simple enough to be used at science fairs and family science nights. Students who have participated in "Ice, Ice, Baby" have successfully taught these to adults and students at informal events. The lessons are based on education standards which are available on our website www.cresis.ku.edu. This presentation will provide information on the activities, survey results from teachers who have used the material, and other suggested material that can be used before and after the activities.

  1. Analysis of the total system life cycle cost for the Civilian Radioactive Waste Management Program: Volume 2, Supporting information

    International Nuclear Information System (INIS)

    1987-06-01

    This report provides cost estimates for the fifth evaluation of the adequacy of the fee and is consistent with the program strategy and plans. The total-system cost for the reference cases in the improved-performance system is estimated at $32.1 to $38.2 billion (expressed in constant 1986 collars) over the entire life of the system, or $1.5 to $1.6 billion more than that of the authorized system (i.e., the system without an MRS facility). The current estimate of the total-system cost for the reference cases in the improved-performance system is $3.8 to $5.4 billion higher than the estimate for the same system in the 1986 TSLCC analysis. In the case with the maximum increase, nearly all of the higher cost is due to a $5.2-billion increase in the costs of development and evaluation (D and E); all other system costs are essentially unchanged. The cost difference between the improved-performance system and the authorized system is smaller than the difference estimated in last year's TSLCC analysis. Volume 2 presents the detailed results for the 1987 analysis of the total-system life cycle cost (TSLCC). It consists of four sections: Section A presents the yearly flows of waste between waste-management facilities for the 12 aggregate logistics cases that were studied; Section B presents the annual total-system costs for each of the 30 TSLCC cases by major cost category; Section C presents the annual costs for the disposal of 16,000 canisters of defense high-level waste (DHLW) by major cost category for each of the 30 TSLCC cases; and Section D presents a summary of the cost-allocation factors that were calculated to determine the defense waste share of the total-system costs

  2. Total physical activity volume, physical activity intensity, and metabolic syndrome: 1999-2004 National Health and Nutrition Examination Survey.

    Science.gov (United States)

    Churilla, James R; Fitzhugh, Eugene C

    2012-02-01

    This study examined the association of total physical activity volume (TPAV) and physical activity (PA) from three domains [leisure-time physical activity (LTPA), domestic, transportation] with metabolic syndrome. We also investigated the relationship between LTPA intensity and metabolic syndrome risk. Sample included adults who participated in the 1999-2004 National Health and Nutrition Examination Survey. Physical activity measures were created for TPAV, LTPA, domestic PA, and transportational PA. For each, a six-level measure based upon no PA (level 1) and quintiles (levels 2-6) of metabolic equivalents (MET)·min·wk(-1) was created. A three-level variable associated with the current Department of Health and Human Services (DHHS) PA recommendation was also created. SAS and SUDAAN were used for the statistical analysis. Adults reporting the greatest volume of TPAV and LTPA were found to be 36% [odds ratio (OR) 0.64; 95% confidence interval (CI) 0.49-0.83] and 42% (OR 0.58; 95% CI 0.43-0.77), respectively, less likely to have metabolic syndrome. Domestic and transportational PA provided no specific level of protection from metabolic syndrome. Those reporting a TPAV that met the DHHS PA recommendation were found to be 33% (OR 0.67; 95%; CI 0.55-0.83) less likely to have metabolic syndrome compared to their sedentary counterparts. Adults reporting engaging in only vigorous-intensity LTPA were found to be 37% (OR 0.63; 95 CI 0.42-0.96) to 56% (OR 0.44; 95% CI 0.29-0.67) less likely to have metabolic syndrome. Volume, intensity, and domain of PA may all play important roles in reducing the prevalence and risk of metabolic syndrome.

  3. Total energy cycle assessment of electric and conventional vehicles: an energy and environmental analysis. Volume 1: technical report

    Energy Technology Data Exchange (ETDEWEB)

    Cuenca, R.; Formento, J.; Gaines, L.; Marr, B.; Santini, D.; Wang, M. [Argonne National Lab., IL (United States); Adelman, S.; Kline, D.; Mark, J.; Ohi, J.; Rau, N. [National Renewable Energy Lab., Golden, CO (United States); Freeman, S.; Humphreys, K.; Placet, M. [Pacific Northwest National Lab., Richland, WA (United States)

    1998-01-01

    This report compares the energy use, oil use and emissions of electric vehicles (EVs) with those of conventional, gasoline-powered vehicles (CVs) over the total life cycle of the vehicles. The various stages included in the vehicles` life cycles include vehicle manufacture, fuel production, and vehicle operation. Disposal is not included. An inventory of the air emissions associated with each stage of the life cycle is estimated. Water pollutants and solid wastes are reported for individual processes, but no comprehensive inventory is developed. Volume I contains the major results, a discussion of the conceptual framework of the study, and summaries of the vehicle, utility, fuel production, and manufacturing analyses. It also contains summaries of comments provided by external peer reviewers and brief responses to these comments.

  4. Stereotactic ultrasound for target volume definition in a patient with prostate cancer and bilateral total hip replacement.

    Science.gov (United States)

    Boda-Heggemann, Judit; Haneder, Stefan; Ehmann, Michael; Sihono, Dwi Seno Kuncoro; Wertz, Hansjörg; Mai, Sabine; Kegel, Stefan; Heitmann, Sigrun; von Swietochowski, Sandra; Lohr, Frank; Wenz, Frederik

    2015-01-01

    Target-volume definition for prostate cancer in patients with bilateral metal total hip replacements (THRs) is a challenge because of metal artifacts in the planning computed tomography (CT) scans. Magnetic resonance imaging (MRI) can be used for matching and prostate delineation; however, at a spatial and temporal distance from the planning CT, identical rectal and vesical filling is difficult to achieve. In addition, MRI may also be impaired by metal artifacts, even resulting in spatial image distortion. Here, we present a method to define prostate target volumes based on ultrasound images acquired during CT simulation and online-matched to the CT data set directly at the planning CT. A 78-year-old patient with cT2cNxM0 prostate cancer with bilateral metal THRs was referred to external beam radiation therapy. T2-weighted MRI was performed on the day of the planning CT with preparation according to a protocol for reproducible bladder and rectal filling. The planning CT was obtained with the immediate acquisition of a 3-dimensional ultrasound data set with a dedicated stereotactic ultrasound system for online intermodality image matching referenced to the isocenter by ceiling-mounted infrared cameras. MRI (offline) and ultrasound images (online) were thus both matched to the CT images for planning. Daily image guided radiation therapy (IGRT) was performed with transabdominal ultrasound and compared with cone beam CT. Because of variations in bladder and rectal filling and metal-induced image distortion in MRI, soft-tissue-based matching of the MRI to CT was not sufficient for unequivocal prostate target definition. Ultrasound-based images could be matched, and prostate, seminal vesicles, and target volumes were reliably defined. Daily IGRT could be successfully completed with transabdominal ultrasound with good accordance between cone beam CT and ultrasound. For prostate cancer patients with bilateral THRs causing artifacts in planning CTs, ultrasound referenced to

  5. Numerical modelling of thermodynamics and dynamics of sea ice in the Baltic Sea

    Directory of Open Access Journals (Sweden)

    A. Herman

    2011-04-01

    Full Text Available In this paper, a numerical dynamic-thermo-dynamic sea-ice model for the Baltic Sea is used to analyze the variability of ice conditions in three winter seasons. The modelling results are validated with station (water temperature and satellite data (ice concentration as well as by qualitative comparisons with the Swedish Meteorological and Hydrological Institute ice charts. Analysis of the results addresses two major questions. One concerns effects of meteorological forcing on the spatio-temporal distribution of ice concentration in the Baltic. Patterns of correlations between air temperature, wind speed, and ice-covered area are demonstrated to be different in larger, more open sub-basins (e.g., the Bothnian Sea than in the smaller ones (e.g., the Bothnian Bay. Whereas the correlations with the air temperature are positive in both cases, the influence of wind is pronounced only in large basins, leading to increase/decrease of areas with small/large ice concentrations, respectively. The other question concerns the role of ice dynamics in the evolution of the ice cover. By means of simulations with the dynamic model turned on and off, the ice dynamics is shown to play a crucial role in interactions between the ice and the upper layers of the water column, especially during periods with highly varying wind speeds and directions. In particular, due to the fragmentation of the ice cover and the modified surface fluxes, the ice dynamics influences the rate of change of the total ice volume, in some cases by as much as 1 km3 per day. As opposed to most other numerical studies on the sea-ice in the Baltic Sea, this work concentrates on the short-term variability of the ice cover and its response to the synoptic-scale forcing.

  6. Single-slice epicardial fat area measurement. Do we need to measure the total epicardial fat volume?

    International Nuclear Information System (INIS)

    Oyama, Noriko; Goto, Daisuke; Ito, Yoichi M.

    2011-01-01

    The aim of this study was to assess a method for measuring epicardial fat volume (EFV) by means of a single-slice area measurement. We investigated the relation between a single-slice fat area measurement and total EFV. A series of 72 consecutive patients (ages 65±11 years; 36 men) who had undergone cardiac computed tomography (CT) on a 64-slice multidetector scanner with prospective electrocardiographic triggering were retrospectively reviewed. Pixels in the pericardium with a density range from -230 to -30 Hounsfield units were considered fat, giving the per-slice epicardial fat area (EFA). The EFV was estimated by the summation of EFAs multiplied by the slice thickness. We investigated the relation between total EFV and each EFA. EFAs measured at several anatomical landmarks - right pulmonary artery, origins of the left main coronary artery, right coronary artery, coronary sinus - all correlated with the EFV (r=0.77-0.92). The EFA at the LMCA level was highly reproducible and showed an excellent correlation with the EFV (r=0.92). The EFA is significantly correlated with the EFV. The EFA is a simple, quick method for representing the time-consuming EFV, which has been used as a predictive indicator of cardiovascular diseases. (author)

  7. Age and total and free prostate-specific antigen levels for predicting prostate volume in patients with benign prostatic hyperplasia.

    Science.gov (United States)

    Coban, Soner; Doluoglu, Omer Gokhan; Keles, Ibrahim; Demirci, Hakan; Turkoglu, Ali Riza; Guzelsoy, Muhammet; Karalar, Mustafa; Demirbas, Murat

    2016-06-01

    To investigate the predictive values of free prostate-specific antigen (fPSA), total PSA (tPSA) and age on the prostate volume. The data of 2148 patients with lower urinary tract symptoms were analyzed retrospectively. The patients who had transrectal ultrasonography guided 10 core biopsies owing to the findings obtained on digital rectal examination and presence of high PSA levels (PSA = 2.5-10 ng/dl), and proven to have BPH histopathologically were included in the study. Age, tPSA, fPSA and the prostate volumes (PV) of the patients were noted. One thousand patients that fulfilled the inclusion criteria were included in the study. The PV of the patients were significantly correlated with age, tPSA and fPSA (p < 0.001 and r = 0.307, p < 0.001 and r = 0.382, p < 0.001 and r = 0.296, respectively). On linear regression model, fPSA was found as a stronger predictive for PV (AUC = 0.75, p < 0.001) when compared to age (AUC = 0.64, p < 0.001), and tPSA (AUC = 0.69, p = 0.013). Although tPSA is an important prognostic factor for predicting PV, the predictive value of fPSA is higher. PV can easily be predicted by using age, and serum tPSA and fPSA levels.

  8. Association Between Provider Volume and Comorbidity on Hospital Utilization and Outcomes of Total Hip Arthroplasty Among National Health Insurance Enrollees

    Directory of Open Access Journals (Sweden)

    Chung-Shih Huang

    2011-06-01

    Conclusions: This study revealed that the volume of THAs performed by individual surgeons was a more important determinant of hospital utilization than hospital volume. Perioperative adverse events were associated with patients' age and comorbidity.

  9. Icing losses on wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Duncan, T.; Fotsing, I.; Pearson, S. [Garrad Hassan Canada Inc., Ottawa, ON (Canada)

    2010-07-01

    This PowerPoint presentation discussed some of the energy losses that can occur as a result of icing on wind turbines. Airfoil deterioration can occur in the presence of rime and glaze ice. Anemometers are also impacted by ice, and shut-downs can occur as a result of icing events. Availability deficits that occur during the winter months can lead to annual energy losses of 0.5 percent. The impact of icing events on total wind power energy production in Quebec is estimated at between 1.3 percent to 2.7 percent. Ice loss estimates are considered during the pre-construction phases of wind power projects. However, ice loss prediction methods are often inaccurate. Studies have demonstrated that preconstruction masts show a reasonable correlation with wind turbine icing, and that icing losses are site-specific. tabs., figs.

  10. Using ice melting and ice rolling technologies to remove ice from sub-transmission and transmission lines at Manitoba Hydro

    International Nuclear Information System (INIS)

    Farias, A. R.

    1999-01-01

    Development of an of an Ice Storm Management program by Manitoba Hydro to reduce ice storm damage to its 8 kV feeders to 115 kV transmission lines, is discussed. The program consists of the de-icing of overhead lines, either by ice melting, or ice rolling. Ice melting involves the placement of a three-phase short at a calculated point. The term ice rolling denotes a process of mechanically stripping the ice from conductors. The most recent major ice storm experienced by Manitoba Hydro was in the winter of 1997/1998. During the period from February 6 to February 17, 1998, a total of 83 'ice melt' procedures were performed to melt the ice from 2,628 km of overhead line (7,883 km of conductor), in addition to 'ice rolling'. This paper describes Manitoba Hydro's 25-years' experience with ice melting and it also describes the advantages and disadvantages of both ice melting and ice rolling. Although not a panacea to combat the effects of ice storms, ice melting was found to be the most effective way of removing ice from overhead transmission and sub-transmission lines. Ice rolling was also found to be effective. Other tools that have been found to be useful by various utilities in combating ice storm damage include improved structure and line design, system design that provide more redundancies and emergency sources, and standby generators at critical load points

  11. Fort Hood Solar Total Energy Project. Volume II. Preliminary design. Part 1. System criteria and design description. Final report

    Energy Technology Data Exchange (ETDEWEB)

    None,

    1979-01-01

    This volume documents the preliminary design developed for the Solar Total Energy System to be installed at Fort Hood, Texas. Current system, subsystem, and component designs are described and additional studies which support selection among significant design alternatives are presented. Overall system requirements which form the system design basis are presented. These include program objectives; performance and output load requirements; industrial, statutory, and regulatory standards; and site interface requirements. Material in this section will continue to be issued separately in the Systems Requirements Document and maintained current through revision throughout future phases of the project. Overall system design and detailed subsystem design descriptions are provided. Consideration of operation and maintenance is reflected in discussion of each subsystem design as well as in an integrated overall discussion. Included are the solar collector subsystem; the thermal storage subsystem, the power conversion sybsystem (including electrical generation and distribution); the heating/cooling and domestic hot water subsystems; overall instrumentation and control; and the STES building and physical plant. The design of several subsystems has progressed beyond the preliminary stage; descriptions for such subsystems are therefore provided in more detail than others to provide complete documentation of the work performed. In some cases, preliminary design parameters require specific verificaton in the definitive design phase and are identified in the text. Subsystem descriptions will continue to be issued and revised separately to maintain accuracy during future phases of the project. (WHK)

  12. On the Ice Nucleation Spectrum

    Science.gov (United States)

    Barahona, D.

    2012-01-01

    This work presents a novel formulation of the ice nucleation spectrum, i.e. the function relating the ice crystal concentration to cloud formation conditions and aerosol properties. The new formulation is physically-based and explicitly accounts for the dependency of the ice crystal concentration on temperature, supersaturation, cooling rate, and particle size, surface area and composition. This is achieved by introducing the concepts of ice nucleation coefficient (the number of ice germs present in a particle) and nucleation probability dispersion function (the distribution of ice nucleation coefficients within the aerosol population). The new formulation is used to generate ice nucleation parameterizations for the homogeneous freezing of cloud droplets and the heterogeneous deposition ice nucleation on dust and soot ice nuclei. For homogeneous freezing, it was found that by increasing the dispersion in the droplet volume distribution the fraction of supercooled droplets in the population increases. For heterogeneous ice nucleation the new formulation consistently describes singular and stochastic behavior within a single framework. Using a fundamentally stochastic approach, both cooling rate independence and constancy of the ice nucleation fraction over time, features typically associated with singular behavior, were reproduced. Analysis of the temporal dependency of the ice nucleation spectrum suggested that experimental methods that measure the ice nucleation fraction over few seconds would tend to underestimate the ice nuclei concentration. It is shown that inferring the aerosol heterogeneous ice nucleation properties from measurements of the onset supersaturation and temperature may carry significant error as the variability in ice nucleation properties within the aerosol population is not accounted for. This work provides a simple and rigorous ice nucleation framework where theoretical predictions, laboratory measurements and field campaign data can be

  13. Insignificant change in Antarctic snowmelt volume since 1979

    NARCIS (Netherlands)

    Kuipers Munneke, P.; Picard, G.; van den Broeke, M.R.; Lenaerts, J.T.M.; van Meijgaard, E.

    2012-01-01

    Surface snowmelt is widespread in coastal Antarctica. Satellite-based microwave sensors have been observing melt area and duration for over three decades. However, these observations do not reveal the total volume of meltwater produced on the ice sheet. Here we present an Antarctic melt volume

  14. Ice recrystallization inhibition in ice cream as affected by ice structuring proteins from winter wheat grass.

    Science.gov (United States)

    Regand, A; Goff, H D

    2006-01-01

    Ice recrystallization in quiescently frozen sucrose solutions that contained some of the ingredients commonly found in ice cream and in ice cream manufactured under commercial conditions, with or without ice structuring proteins (ISP) from cold-acclimated winter wheat grass extract (AWWE), was assessed by bright field microscopy. In sucrose solutions, critical differences in moisture content, viscosity, ionic strength, and other properties derived from the presence of other ingredients (skim milk powder, corn syrup solids, locust bean gum) caused a reduction in ice crystal growth. Significant ISP activity in retarding ice crystal growth was observed in all solutions (44% for the most complex mix) containing 0.13% total protein from AWWE. In heat-shocked ice cream, ice recrystallization rates were significantly reduced 40 and 46% with the addition of 0.0025 and 0.0037% total protein from AWWE. The ISP activity in ice cream was not hindered by its inclusion in mix prior to pasteurization. A synergistic effect between ISP and stabilizer was observed, as ISP activity was reduced in the absence of stabilizer in ice cream formulations. A remarkably smoother texture for ice creams containing ISP after heat-shock storage was evident by sensory evaluation. The efficiency of ISP from AWWE in controlling ice crystal growth in ice cream has been demonstrated.

  15. Comparison between total lung capacity and residual volume values obtained by pletysmography and single breath methods with methane

    Directory of Open Access Journals (Sweden)

    Ricardo Marques Dias

    2006-11-01

    Full Text Available We analyzed pulmonary function tests of twenty asthmatic patients from Gaffrée e Guinle University Hospital, classified according to Brazilian Guidelines for Asthma (2002, similar to GINA, into mild persistent or moderate (9 or severe (11 asthma. We obtained parameters from spirometry, plethysmograph(PL and single breath technique for diffusion capacity (SB, with methane. Total lung capacity and residual volume were called TLCPL and RVPL when measured by pletysmography and TLCSB and RVSB when determined by single breath test. There were 13 women and 7 men with mean age of 47.6 years. The pulmonary dysfunction degree to FEV1/FVC was 58.8% with CI95=53.9 to 63.6. The mean values in litres for TLCPL (5.94 and RVPL (2.55 were significantly higher than for TLCSB (4.73 and RVSB (1.66. Multiple regression equations were determined for TLCPL e RVPL using only single breath values, TLCSB or RVSB, and spirographic parameters, with significant regression coefficients. However, the inclusion of spirometric parameters, except for FVC, did not improve the predicted capacity for the equations. Considering only the TLCSB, r2=0.79, the equation is: TLCPL=(TLCSB*1.025+1.088, with EPE=0.64. The regression for RVPL, r2=0.23, is: RVPL=(RVSB*0.9268+1.012. The results obtained after bronchodilation with 400 mcg of salbutamol did not improve the regression. We concluded that the SB technique did not obtain the same results as pletysmography for TLC and RV, but for TLC this difference can be predicted. Resumo: Foram analisados exames de função pulmonar de 20 asmáticos, em acompanhamento no HU Gaffrée Guinle, classificados, segundo o Consenso Brasileiro (2002, em asma leve persistente ou moderada (9 e grave (11. Foram obtidos os valores dos parâmetros da espirografia, da pletismografia e da técnica de respiração única, com metano, para a medida da difusão pulmonar (DLco. Assim, a capacidade pulmonar total e o volume residual, quando

  16. Winter sea ice export from the Laptev Sea preconditions the local summer sea ice cover and fast ice decay

    Directory of Open Access Journals (Sweden)

    P. Itkin

    2017-10-01

    Full Text Available Ice retreat in the eastern Eurasian Arctic is a consequence of atmospheric and oceanic processes and regional feedback mechanisms acting on the ice cover, both in winter and summer. A correct representation of these processes in numerical models is important, since it will improve predictions of sea ice anomalies along the Northeast Passage and beyond. In this study, we highlight the importance of winter ice dynamics for local summer sea ice anomalies in thickness, volume and extent. By means of airborne sea ice thickness surveys made over pack ice areas in the south-eastern Laptev Sea, we show that years of offshore-directed sea ice transport have a thinning effect on the late-winter sea ice cover. To confirm the preconditioning effect of enhanced offshore advection in late winter on the summer sea ice cover, we perform a sensitivity study using a numerical model. Results verify that the preconditioning effect plays a bigger role for the regional ice extent. Furthermore, they indicate an increase in volume export from the Laptev Sea as a consequence of enhanced offshore advection, which has far-reaching consequences for the entire Arctic sea ice mass balance. Moreover we show that ice dynamics in winter not only preconditions local summer ice extent, but also accelerate fast-ice decay.

  17. Structural imaging of the brain reveals decreased total brain and total gray matter volumes in obese but not in lean women with polycystic ovary syndrome compared to body mass index-matched counterparts.

    Science.gov (United States)

    Ozgen Saydam, Basak; Has, Arzu Ceylan; Bozdag, Gurkan; Oguz, Kader Karli; Yildiz, Bulent Okan

    2017-07-01

    To detect differences in global brain volumes and identify relations between brain volume and appetite-related hormones in women with polycystic ovary syndrome (PCOS) compared to body mass index-matched controls. Forty subjects participated in this study. Cranial magnetic resonance imaging and measurements of fasting ghrelin, leptin and glucagon-like peptide 1 (GLP-1), as well as GLP-1 levels during mixed-meal tolerance test (MTT), were performed. Total brain volume and total gray matter volume (GMV) were decreased in obese PCOS compared to obese controls (p lean PCOS and controls did not show a significant difference. Secondary analyses of regional brain volumes showed decreases in GMV of the caudate nucleus, ventral diencephalon and hippocampus in obese PCOS compared to obese controls (p lean patients with PCOS had lower GMV in the amygdala than lean controls (p PCOS, suggests volumetric reductions in global brain areas in obese women with PCOS. Functional studies with larger sample size are needed to determine physiopathological roles of these changes and potential effects of long-term medical management on brain structure of PCOS.

  18. Association of translocator protein total distribution volume with duration of untreated major depressive disorder: a cross-sectional study.

    Science.gov (United States)

    Setiawan, Elaine; Attwells, Sophia; Wilson, Alan A; Mizrahi, Romina; Rusjan, Pablo M; Miler, Laura; Xu, Cynthia; Sharma, Sarita; Kish, Stephen; Houle, Sylvain; Meyer, Jeffrey H

    2018-04-01

    People with major depressive disorder frequently exhibit increasing persistence of major depressive episodes. However, evidence for neuroprogression (ie, increasing brain pathology with longer duration of illness) is scarce. Microglial activation, which is an important component of neuroinflammation, is implicated in neuroprogression. We examined the relationship of translocator protein (TSPO) total distribution volume (V T ), a marker of microglial activation, with duration of untreated major depressive disorder, and with total illness duration and antidepressant exposure. In this cross-sectional study, we recruited participants aged 18-75 years from the Toronto area and the Centre for Addiction and Mental Health (Toronto, ON, Canada). Participants either had major depressive episodes secondary to major depressive disorder or were healthy, as confirmed with a structured clinical interview and consultation with a study psychiatrist. To be enrolled, participants with major depressive episodes had to score a minimum of 17 on the 17-item Hamilton Depression Rating Scale, and had to be medication free or taking a stable dose of medication for at least 4 weeks before PET scanning. Eligible participants were non-smokers; had no history of or concurrent alcohol or substance dependence, neurological illness, autoimmune disorder, or severe medical problems; and were free from acute medical illnesses for the previous 2 weeks before PET scanning. Participants were excluded if they had used brain stimulation treatments within the 6 months before scanning, had used anti-inflammatory drugs lasting at least 1 week within the past month, were taking hormone replacement therapy, had psychotic symptoms, had bipolar disorder (type I or II) or borderline antisocial personality disorder, or were pregnant or breastfeeding. We scanned three primary grey-matter regions of interest (prefrontal cortex, anterior cingulate cortex, and insula) and 12 additional regions and subregions using 18

  19. Greenland Ice Sheet Mass Balance

    Science.gov (United States)

    Reeh, N.

    1984-01-01

    Mass balance equation for glaciers; areal distribution and ice volumes; estimates of actual mass balance; loss by calving of icebergs; hydrological budget for Greenland; and temporal variations of Greenland mass balance are examined.

  20. Let's Make Metric Ice Cream

    Science.gov (United States)

    Zimmerman, Marianna

    1975-01-01

    Describes a classroom activity which involved sixth grade students in a learning situation including making ice cream, safety procedures in a science laboratory, calibrating a thermometer, using metric units of volume and mass. (EB)

  1. Ice Cores

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Records of past temperature, precipitation, atmospheric trace gases, and other aspects of climate and environment derived from ice cores drilled on glaciers and ice...

  2. Increased Severe Trauma Patient Volume is Associated With Survival Benefit and Reduced Total Health Care Costs: A Retrospective Observational Study Using a Japanese Nationwide Administrative Database.

    Science.gov (United States)

    Endo, Akira; Shiraishi, Atsushi; Fushimi, Kiyohide; Murata, Kiyoshi; Otomo, Yasuhiro

    2017-06-07

    The aim of this study was to evaluate the associations of severe trauma patient volume with survival benefit and health care costs. The effect of trauma patient volume on survival benefit is inconclusive, and reports on its effects on health care costs are scarce. We conducted a retrospective observational study, including trauma patients who were transferred to government-approved tertiary emergency hospitals, or hospitals with an intensive care unit that provided an equivalent quality of care, using a Japanese nationwide administrative database. We categorized hospitals according to their annual severe trauma patient volumes [1 to 50 (reference), 51 to 100, 101 to 150, 151 to 200, and ≥201]. We evaluated the associations of volume categories with in-hospital survival and total cost per admission using a mixed-effects model adjusting for patient severity and hospital characteristics. A total of 116,329 patients from 559 hospitals were analyzed. Significantly increased in-hospital survival rates were observed in the second, third, fourth, and highest volume categories compared with the reference category [94.2% in the highest volume category vs 88.8% in the reference category, adjusted odds ratio (95% confidence interval, 95% CI) = 1.75 (1.49-2.07)]. Furthermore, significantly lower costs (in US dollars) were observed in the second and fourth categories [mean (standard deviation) for fourth vs reference = $17,800 ($17,378) vs $20,540 ($32,412), adjusted difference (95% CI) = -$2559 (-$3896 to -$1221)]. Hospitals with high volumes of severe trauma patients were significantly associated with a survival benefit and lower total cost per admission.

  3. Ice Cream

    NARCIS (Netherlands)

    Scholten, E.

    2014-01-01

    Ice cream is a popular dessert, which owes its sensorial properties (mouth feel) to its complex microstructure. The microstructure is a result of the combination of the ingredients and the production process. Ice cream is produced by simultaneous freezing and shearing of the ice cream mix, which

  4. Ice targets

    International Nuclear Information System (INIS)

    Pacheco, C.; Stark, C.; Tanaka, N.; Hodgkins, D.; Barnhart, J.; Kosty, J.

    1979-12-01

    This report presents a description of ice targets that were constructed for research work at the High Resolution Spectrometer (HRS) and at the Energetic Pion Channel and Spectrometer (EPICS). Reasons for using these ice targets and the instructions for their construction are given. Results of research using ice targets will be published at a later date

  5. History of sea ice in the Arctic

    DEFF Research Database (Denmark)

    Polyak, Leonid; Alley, Richard B.; Andrews, John T.

    2010-01-01

    Arctic sea-ice extent and volume are declining rapidly. Several studies project that the Arctic Ocean may become seasonally ice-free by the year 2040 or even earlier. Putting this into perspective requires information on the history of Arctic sea-ice conditions through the geologic past. This inf......Arctic sea-ice extent and volume are declining rapidly. Several studies project that the Arctic Ocean may become seasonally ice-free by the year 2040 or even earlier. Putting this into perspective requires information on the history of Arctic sea-ice conditions through the geologic past...... Optimum, and consistently covered at least part of the Arctic Ocean for no less than the last 13–14 million years. Ice was apparently most widespread during the last 2–3 million years, in accordance with Earth’s overall cooler climate. Nevertheless, episodes of considerably reduced sea ice or even...

  6. Determination of the total blood volume of the rat using chromium 51 (1962); Determination du volume sanguin total chez le rat a l'aide du chrome 51 (1962)

    Energy Technology Data Exchange (ETDEWEB)

    Bernard, Y; Rinaldi, R [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1962-07-01

    In various experiments it is important that the rat's blood volume should be known and it is essential that it could be worked out by simply weighing the animal. Therefore authors decided to work out systematically with chromium 51 blood volume for rats with different weights. Results have shown that blood volume for 100 g is 5.55 ml and that it does not seen to vary with the weight of animals. (authors) [French] La connaissance de la masse sanguine chez le rat est indispensable dans de nombreuses experiences et il est essentiel de pouvoir l'evaluer apres une simple pesee de l'animal. C'est dans ce but que les auteurs ont entrepris la determination systematique de la masse sanguine a l'aide du chrome 51 chez des rats de poids differents. Les resultats obtenus ont montre que la masse sanguine rapportee a 100 grammes d'animal est de 5,53 millilitres, et qu'elle ne parait pas varier avec le poids de l'animal. (auteurs)

  7. High-volume infiltration analgesia in total knee arthroplasty: a randomized, double-blind, placebo-controlled trial

    DEFF Research Database (Denmark)

    Andersen, L.O.; Husted, H.; Otte, K.S.

    2008-01-01

    with a detailed description of the infiltration technique. METHODS: In a randomized, double-blind, placebo-controlled trial in 12 patients undergoing bilateral knee arthroplasty, saline or high-volume (170 ml) ropivacaine (0.2%) with epinephrine was infiltrated around each knee, with repeated doses administered...

  8. The ICES historical plankton data collected from1902-08-01 to 1912-06-05 and digitized from historical ICES manuscripts (NODC Accession 0121310)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The ICES Historical Plankton Dataset digitized from seven historical ICES volumes. Data were downloaded at http://ecosystemdata.ices.dk/historicalplankton

  9. Search for tau-neutrino induced cascades in the IceCube detector

    Energy Technology Data Exchange (ETDEWEB)

    Usner, Marcel; Kowalski, Marek [DESY, Zeuthen (Germany); Collaboration: IceCube-Collaboration

    2016-07-01

    The IceCube Neutrino Observatory at the South Pole is a Cherenkov detector built to measure high-energy neutrinos from cosmic sources. A total volume of about one cubic kilometer of the Antarctic ice is instrumented with 5160 optical modules. A tau lepton is created in the charged current interaction of a tau neutrino with an ice nucleus. The Double Bang signature links two subsequent cascades from the hadronic interaction and the tau decay within the detection volume. It can only be resolved at the highest energies around 1 PeV where the decay length of the tau is about 50 m. The work is focused on optimizing reconstruction methods of Double Bang events incorporating the latest ice model. The goal is to measure a flavor ratio that, for the first time, is sensitive to tau neutrinos.

  10. The effect of post-wash total progressive motile sperm count and semen volume on pregnancy outcomes in intrauterine insemination cycles: a retrospective study.

    Science.gov (United States)

    Ok, Elvan Koyun; Doğan, Omer Erbil; Okyay, Recep Emre; Gülekli, Bülent

    2013-01-01

    The purpose of this study was to determine the impact of post-wash total progressive motile sperm count (TPMSC) and semen volume on pregnancy outcomes in intrauterine insemination (IUI) cycles. The retrospective study included a total of 156 cycles (141 couples) and was performed in our center over a 24-month period. The semen parameters were recorded for each man and each insemination. The semen samples were re-evaluated after the preparation process. Post-wash TPMSC values were divided into four groups; Group 1: 10×10(6). Post-wash inseminated semen volume was divided into three groups; Group 1: 0.3 mL; Group 2: 0.4 mL; Group 3: 0.5 mL. The effect of post-wash total progressive motile sperm and semen volume on pregnancy outcomes was evaluated. The pregnancy rates per cycle and per couple were 27.56% and 30.49%, respectively. There was not a significant relationship between the inseminated semen volume and pregnancy rate (p>0.05). However, a significant linear-by-linear association was documented between the TPMSC and pregnancy rate (p=0.042). Our findings suggest that the post-wash inseminated semen volume should be between 0.3-0.5 mL. An average post-wash total motile sperm count of 10×10(6) may be a useful threshold value for IUI success, but more studies are needed to determine a cut-off value for TPMSC.

  11. Greenland Ice sheet mass balance from satellite and airborne altimetry

    DEFF Research Database (Denmark)

    Khan, Shfaqat Abbas; Bevis, M. G.; Wahr, J. M.

    Ice loss from the Greenland Ice Sheet (GrIS) is dominated by loss in the marginal areas. Dynamic induced ice loss and its associated ice surface lowering is often largest close to the glacier calving front and may vary from rates of tens of meters per years to a few meters per year over relatively...... short distances. Hence, high spatial resolution data are required to accurately estimate volume changes. Here, we estimate ice volume change rate of the Greenland ice sheet using data from Ice, Cloud and land Elevation Satellite (ICESat) laser altimeter during 2003-2009 and CryoSat-2 data during 2010...

  12. Indoor air quality in ice skating rinks in Hong Kong

    International Nuclear Information System (INIS)

    Guo, H.; Lee, S.C.; Chan, L.Y.

    2004-01-01

    Indoor air quality in ice skating rinks has become a public concern due to the use of propane- or gasoline-powered ice resurfacers and edgers. In this study, the indoor air quality in three ice rinks with different volumes and resurfacer power sources (propane and gasoline) was monitored during usual operating hours. The measurements included continuous recording of carbon monoxide (CO), carbon dioxide (CO 2 ), total volatile organic compounds (TVOC), particulate matter with a diameter less than 2.5 μm (PM 2.5 ), particulate matter with diameter less than 10 μm (PM 10 ), nitric oxide (NO), nitrogen dioxide (NO 2 ), nitrogen oxide (NO x ), and sulfur dioxide (SO 2 ). The average CO, CO 2 , and TVOC concentrations ranged from 3190 to 6749 μg/m 3 , 851 to 1329 ppm, and 550 to 765 μg/m 3 , respectively. The average NO and NO 2 concentrations ranged from 69 to 1006 μg/m 3 and 58 to 242 μg/m 3 , respectively. The highest CO and TVOC levels were observed in the ice rink which a gasoline-fueled resurfacer was used. The highest NO and NO 2 levels were recorded in the ice rink with propane-fueled ice resurfacers. The air quality parameters of PM 2.5 , PM 10 , and SO 2 were fully acceptable in these ice rinks according to HKIAQO standards. Overall, ice resurfacers with combustion engines cause indoor air pollution in ice rinks in Hong Kong. This conclusion is similar to those of previous studies in Europe and North America

  13. IMMUNOMETABOLIC RESPONSES AFTER SHORT AND MODERATE REST INTERVALS TO STRENGTH EXERCISE WITH AND WITHOUT SIMILAR TOTAL VOLUME.

    Directory of Open Access Journals (Sweden)

    Ricardo Agostinete

    2016-10-01

    Full Text Available This study investigated the influence of short and moderate intervals of recovery with and without equated volume during an acute bout exhaustive strength exercise on metabolic, hormonal and inflammatory responses in healthy adults. Eight physically active men (23.5 ±3.1 performed three randomized sequences: Short (70% of 1RM with 30 seconds of rest; Moderate (70% of 1RM with 90 seconds of rest; and Volume-Equated Short (70% of 1 RM with 30 seconds of rest between sets with a repetition volume equal to that performed in Moderate. All sequences of exercises were performed until movement failure in the squat, bench press and T-bar row exercises, respectively. Glucose, lactate, testosterone, IL-6, IL-10, IL-1ra and MCP-1 levels were assessed at rest, immediate post-exercise, and 1 hour post. There was a main effect of time for testosterone (p<0.001. The post hoc indicated differences between post-exercise and rest and post-1 hour and post-exercise (p<0.001. Lactate increased post-exercise when compared to pre and post-1 hour (p<0.001 and maintained higher post-1 hour in relation to rest. IL-6 was greater post-exercise than rest (p= 0.045 and post-1 hour and rest (p= 0.020. IL-10 was greater post-exercise (p= 0.007 and post-1 hour (p=0.002 than rest. IL-1ra increased post-exercise in relation to rest (p=0.003 and MCP-1 was greater post-exercise than rest (p<0.001 and post-1 hour (p=0.043. There were no significant differences between conditions or interaction. Thus, both short and moderate intervals of recovery induced greater metabolic, hormonal and inflammatory responses after acute bout of exhaustive strength exercise in healthy adult.

  14. Thermodynamics of high-pressure ice polymorphs : ices III and V

    NARCIS (Netherlands)

    Tchijov, [No Value; Ayala, RB; Leon, GC; Nagornov, O

    Thermodynamic properties of high-pressure ice polymorphs, ices III and V, are studied theoretically. The results of TIP4P molecular dynamics simulations in the NPT ensemble are used to calculate the temperature dependence of the specific volume of ices III and V at pressures 0.25 and 0.5 GPa,

  15. On Sea Ice Characterisation By Multi-Frequency SAR

    Science.gov (United States)

    Grahn, Jakob; Brekke, Camilla; Eltoft, Torbjorn; Holt, Benjamin

    2013-12-01

    By means of polarimetric target decomposition, quad-pol SAR data of sea ice is analysed at two frequency bands. In particular, the non negative eigenvalue decomposition (NNED) is applied on L- and C-band NASA/JPL AIR- SAR data acquired over the Beaufort sea in 2004. The de- composition separates the scattered radar signal into three types, dominated by double, volume and single bounce scattering respectively. Using ground truth derived from RADARSAT-1 and meteorological data, we investigate how the different frequency bands compare in terms of these scattering types. The ground truth contains multi year ice and three types of first year ice of different age and thickness. We find that C-band yields a higher scattered intensity in most ice and scattering types, as well as a more homogeneous intensity. L-band on the other hand yields more pronounced deformation features, such as ridges. The mean intensity contrast between the two thinnest ice types is highest in the double scattering component of C- band, although the contrast of the total signal is greater in L-band. This may indicate that the choice of polarimetric parameters is important for discriminating thin ice types.

  16. The making of salty ice

    International Nuclear Information System (INIS)

    Bove, L.E.

    2009-01-01

    Full text: It is widely accepted that ice, no matter what phase, is unable to incorporate large amount of salt into its structure. This conclusion is based on the observation that upon freezing of saltwater, ice expels the salt almost entirely into brine, a fact which can be exploited to desalinate seawater. Here we show, by neutron diffraction under high pressure, that this behaviour is not an intrinsic physico-chemical property of ice phases. We demonstrate that substantial am mounts of dissolved LiCl can be built homogeneously into the ice VII structure if it is produced by recrystallisation of its glassy state under pressure [1]. Such highly doped or alloyed ice VII has significantly different structural properties compared to pure ice VII, such as a 8% larger unit cell volume, 5 times larger displacement factors, an absence of a transition to an ordered ice VIII structure, plasticity, and most likely ionic conductivity. Our study suggests that there could be a whole new class of salty ices based on various kinds of solutes and high pressure ice forms. (author)

  17. Volume totalizers analysis of pipelines operated by TRANSPETRO National Operational Control Center; Analise de totalizadores de volume em oleodutos operados pelo Centro Nacional de Controle e Operacao da TRANSPETRO

    Energy Technology Data Exchange (ETDEWEB)

    Aramaki, Thiago Lessa; Montalvao, Antonio Filipe Falcao [Petrobras Transporte S.A. (TRANSPETRO), Rio de Janeiro, RJ (Brazil); Marques, Thais Carrijo [Universidade do Estado do Rio de Janeiro (UERJ), RJ (Brazil)

    2012-07-01

    This paper aims to present the results and methodology in the analysis of differences in volume totals used in systems such as batch tracking and leak detection of pipelines operated by the National Center for Operational Control (CNCO) at TRANSPETRO. In order to optimize this type of analysis, software was developed to acquisition and processing of historical data using the methodology developed. The methodology developed takes into account the particularities encountered in systems operated by TRANSPETRO, more specifically, by CNCO. (author)

  18. Deltoid muscle volume affects clinical outcome of reverse total shoulder arthroplasty in patients with cuff tear arthropathy or irreparable cuff tears.

    Directory of Open Access Journals (Sweden)

    Jong Pil Yoon

    Full Text Available We aimed to estimate the interrelation between preoperative deltoid muscle status by measuring the 3-dimensional deltoid muscle volume and postoperative functional outcomes after reverse total shoulder arthroplasty(RTSA. Thirty-five patients who underwent RTSA participated in this study. All patients underwent preoperative magnetic resonance imaging(MRI as well as pre- and postoperative radiography and various functional outcome evaluations at least 1 year. The primary outcome parameter was set as age- and sex-matched Constant scores. The 3-dimensional deltoid muscle model was generated using a medical image processing software and in-house code, and the deltoid muscle volume was calculated automatically. Various clinical and radiographic factors comprising the deltoid muscle volume adjusted for body mass index(BMI were analyzed, and their interrelation with the outcome parameters was appraised using a multivariate analysis. As a result, all practical consequences considerably improved following surgery(all p<0.01. Overall, 20 and 15 indicated a higher and a lower practical consequence than the average, respectively, which was assessed by the matched Constant scores. The deltoid muscle volume adjusted for BMI(p = 0.009, absence of a subscapularis complete tear (p = 0.040, and greater change in acromion-deltoid tuberosity distance(p = 0.013 were associated with higher matched Constant scores. Multivariate analysis indicated that the deltoid muscle volume was the single independent prognostic factor for practical consequences(p = 0.011. In conclusion, the preoperative deltoid muscle volume significantly affected the functional outcome following RTSA in patients with cuff tear arthropathy or irreparable cuff tears. Therefore, more attention should be paid to patients with severe atrophied deltoid muscle who are at a high risk for poor practical consequences subsequent to RTSA.

  19. Deltoid muscle volume affects clinical outcome of reverse total shoulder arthroplasty in patients with cuff tear arthropathy or irreparable cuff tears.

    Science.gov (United States)

    Yoon, Jong Pil; Seo, Anna; Kim, Jeong Jun; Lee, Chang-Hwa; Baek, Seung-Hun; Kim, Shin Yoon; Jeong, Eun Taek; Oh, Kyung-Soo; Chung, Seok Won

    2017-01-01

    We aimed to estimate the interrelation between preoperative deltoid muscle status by measuring the 3-dimensional deltoid muscle volume and postoperative functional outcomes after reverse total shoulder arthroplasty(RTSA). Thirty-five patients who underwent RTSA participated in this study. All patients underwent preoperative magnetic resonance imaging(MRI) as well as pre- and postoperative radiography and various functional outcome evaluations at least 1 year. The primary outcome parameter was set as age- and sex-matched Constant scores. The 3-dimensional deltoid muscle model was generated using a medical image processing software and in-house code, and the deltoid muscle volume was calculated automatically. Various clinical and radiographic factors comprising the deltoid muscle volume adjusted for body mass index(BMI) were analyzed, and their interrelation with the outcome parameters was appraised using a multivariate analysis. As a result, all practical consequences considerably improved following surgery(all pmuscle volume adjusted for BMI(p = 0.009), absence of a subscapularis complete tear (p = 0.040), and greater change in acromion-deltoid tuberosity distance(p = 0.013) were associated with higher matched Constant scores. Multivariate analysis indicated that the deltoid muscle volume was the single independent prognostic factor for practical consequences(p = 0.011). In conclusion, the preoperative deltoid muscle volume significantly affected the functional outcome following RTSA in patients with cuff tear arthropathy or irreparable cuff tears. Therefore, more attention should be paid to patients with severe atrophied deltoid muscle who are at a high risk for poor practical consequences subsequent to RTSA.

  20. Controls on Arctic sea ice from first-year and multi-year survival rates

    Energy Technology Data Exchange (ETDEWEB)

    Hunke, Jes [Los Alamos National Laboratory

    2009-01-01

    The recent decrease in Arctic sea ice cover has transpired with a significant loss of multi year ice. The transition to an Arctic that is populated by thinner first year sea ice has important implications for future trends in area and volume. Here we develop a reduced model for Arctic sea ice with which we investigate how the survivability of first year and multi year ice control the mean state, variability, and trends in ice area and volume.

  1. Predicting Stem Total and Assortment Volumes in an Industrial Pinus taeda L. Forest Plantation Using Airborne Laser Scanning Data and Random Forest

    Directory of Open Access Journals (Sweden)

    Carlos Alberto Silva

    2017-07-01

    Full Text Available Improvements in the management of pine plantations result in multiple industrial and environmental benefits. Remote sensing techniques can dramatically increase the efficiency of plantation management by reducing or replacing time-consuming field sampling. We tested the utility and accuracy of combining field and airborne lidar data with Random Forest, a supervised machine learning algorithm, to estimate stem total and assortment (commercial and pulpwood volumes in an industrial Pinus taeda L. forest plantation in southern Brazil. Random Forest was populated using field and lidar-derived forest metrics from 50 sample plots with trees ranging from three to nine years old. We found that a model defined as a function of only two metrics (height of the top of the canopy and the skewness of the vertical distribution of lidar points has a very strong and unbiased predictive power. We found that predictions of total, commercial, and pulp volume, respectively, showed an adjusted R2 equal to 0.98, 0.98 and 0.96, with unbiased predictions of −0.17%, −0.12% and −0.23%, and Root Mean Square Error (RMSE values of 7.83%, 7.71% and 8.63%. Our methodology makes use of commercially available airborne lidar and widely used mathematical tools to provide solutions for increasing the industry efficiency in monitoring and managing wood volume.

  2. The Attributable Proportion of Specific Leisure-Time Physical Activities to Total Leisure Activity Volume Among US Adults, National Health and Nutrition Examination Survey 1999-2006.

    Science.gov (United States)

    Watson, Kathleen Bachtel; Dai, Shifan; Paul, Prabasaj; Carlson, Susan A; Carroll, Dianna D; Fulton, Janet

    2016-11-01

    Previous studies have examined participation in specific leisure-time physical activities (PA) among US adults. The purpose of this study was to identify specific activities that contribute substantially to total volume of leisure-time PA in US adults. Proportion of total volume of leisure-time PA moderate-equivalent minutes attributable to 9 specific types of activities was estimated using self-reported data from 21,685 adult participants (≥ 18 years) in the National Health and Nutrition Examination Survey 1999-2006. Overall, walking (28%), sports (22%), and dancing (9%) contributed most to PA volume. Attributable proportion was higher among men than women for sports (30% vs. 11%) and higher among women than men for walking (36% vs. 23%), dancing (16% vs. 4%), and conditioning exercises (10% vs. 5%). The proportion was lower for walking, but higher for sports, among active adults than those insufficiently active and increased with age for walking. Compared with other racial/ethnic groups, the proportion was lower for sports among non-Hispanic white men and for dancing among non-Hispanic white women. Walking, sports, and dance account for the most activity time among US adults overall, yet some demographic variations exist. Strategies for PA promotion should be tailored to differences across population subgroups.

  3. Fasting gall bladder volume and lithogenicity in relation to glucose tolerance, total and intra-abdominal fat masses in obese non-diabetic subjects

    DEFF Research Database (Denmark)

    Hendel, H W; Højgaard, L; Andersen, T

    1998-01-01

    OBJECTIVE: To investigate whether total body fat mass or fat distribution and associated metabolic disturbances in glucose and lipid metabolism influence the well known gallstone pathogenetic factors in obese subjects in order to explain why some obese subjects develop gallstones and some do not...... with a specific radioimmunoassay. Insulin sensitivity was measured by the Minimal Model and glucose tolerance by an oral glucose tolerance test (OGTT). Serum lipid concentrations were measured by standard methods. RESULTS: The gallbladder volume in the fasting state increased with increasing intra-abdominal fat...... mass (P=0.006) and was increased in subjects with impaired glucose tolerance (41 vs 27 ml, P=0.001). The lithogenic index was > 1 in all subjects and correlated with total fat mass (P=0.04). CONCLUSION: Gallstone pathogenesis in obesity seems to be influenced by the total body fat mass and its regional...

  4. Effect of Risk Acceptance for Bundled Care Payments on Clinical Outcomes in a High-Volume Total Joint Arthroplasty Practice After Implementation of a Standardized Clinical Pathway.

    Science.gov (United States)

    Kee, James R; Edwards, Paul K; Barnes, Charles L

    2017-08-01

    The Bundled Payments for Care Improvement (BPCI) initiative and the Arkansas Payment Improvement (API) initiative seek to incentivize reduced costs and improved outcomes compared with the previous fee-for-service model. Before participation, our practice initiated a standardized clinical pathway (CP) to reduce length of stay (LOS), readmissions, and discharge to postacute care facilities. This practice implemented a standardized CP focused on patient education, managing patient expectations, and maximizing cost outcomes. We retrospectively reviewed all primary total joint arthroplasty patients during the initial 2-year "at risk" period for both BPCI and API and determined discharge disposition, LOS, and readmission rate. During the "at risk" period, the average LOS decreased in our total joint arthroplasty patients and our patients discharged home >94%. Patients within the BPCI group had a decreased discharge to home and decreased readmission rates after total hip arthroplasty, but also tended to be older than both API and nonbundled payment patients. While participating in the BPCI and API, continued use of a standardized CP in a high-performing, high-volume total joint practice resulted in maintenance of a low-average LOS. In addition, BPCI patients had similar outcomes after total knee arthroplasty, but had decreased rates of discharge to home and readmission after total hip arthroplasty. Copyright © 2017 Elsevier Inc. All rights reserved.

  5. Constraining the thickness of polar ice deposits on Mercury using the Mercury Laser Altimeter and small craters in permanently shadowed regions

    Science.gov (United States)

    Deutsch, Ariel N.; Head, James W.; Chabot, Nancy L.; Neumann, Gregory A.

    2018-05-01

    Radar-bright deposits at the poles of Mercury are located in permanently shadowed regions, which provide thermally stable environments for hosting and retaining water ice on the surface or in the near subsurface for geologic timescales. While the areal distribution of these radar-bright deposits is well characterized, their thickness, and thus their total mass and volume, remain poorly constrained. Here we derive thickness estimates for selected water-ice deposits using small, simple craters visible within the permanently shadowed, radar-bright deposits. We examine two endmember scenarios: in Case I, these craters predate the emplacement of the ice, and in Case II, these craters postdate the emplacement of the ice. In Case I, we find the difference between estimated depths of the original unfilled craters and the measured depths of the craters to find the estimated infill of material. The average estimated infilled material for 9 craters assumed to be overlain with water ice is ∼ 41-14+30 m, where 1-σ standard error of the mean is reported as uncertainty. Reported uncertainties are for statistical errors only. Additional systematic uncertainty may stem from georeferencing the images and topographic datasets, from the radial accuracy of the altimeter measurements, or from assumptions in our models including (1) ice is flat in the bowl-shaped crater and (2) there is negligible ice at the crater rims. In Case II, we derive crater excavation depths to investigate the thickness of the ice layer that may have been penetrated by the impact. While the absence of excavated regolith associated with the small craters observed suggests that impacts generally do not penetrate through the ice deposit, the spatial resolution and complex illumination geometry of images may limit the observations. Therefore, it is not possible to conclude whether the small craters in this study penetrate through the ice deposit, and thus Case II does not provide a constraint on the ice thickness

  6. Fort Hood Solar Total Energy Project. Volume II. Preliminary design. Part 2. System performance and supporting studies. Final report

    Energy Technology Data Exchange (ETDEWEB)

    None,

    1979-01-01

    The preliminary design developed for the Solar Total Energy System to be installed at Fort Hood, Texas, is presented. System performance analysis and evaluation are described. Feedback of completed performance analyses on current system design and operating philosophy is discussed. The basic computer simulation techniques and assumptions are described and the resulting energy displacement analysis is presented. Supporting technical studies are presented. These include health and safety and reliability assessments; solar collector component evaluation; weather analysis; and a review of selected trade studies which address significant design alternatives. Additional supporting studies which are generally specific to the installation site are reported. These include solar availability analysis; energy load measurements; environmental impact assessment; life cycle cost and economic analysis; heat transfer fluid testing; meteorological/solar station planning; and information dissemination. (WHK)

  7. Impact of airflow interaction on inhaled air quality and transport of contaminants in rooms with personalized and total volume ventilation

    DEFF Research Database (Denmark)

    Melikov, Arsen Krikor; Cermak, Radim; Kovar, O.

    2003-01-01

    The impact of airflow interaction on inhaled air quality and transport of contaminants between occupants was studied in regard to pollution from floor covering, human bioeffluents and exhaled air, with combinations of two personalized ventilation systems (PV) with mixing and displacement...... quality with personalized and mixing ventilation was higher or at least similar compared to mixing ventilation alone. In the case of PV combined with displacement ventilation, the interaction caused mixing of the room air, an increase in the transport of bioeffluents and exhaled air between occupants and...... ventilation. In total, 80 L/s of clean air supplied at 20°C was distributed between the ventilation systems at different combinations of personalized airflow rate. Two breathing thermal manikins were used to simulate occupants in a full-scale test room. Regardless of the airflow interaction, the inhaled air...

  8. Sensitivity of open-water ice growth and ice concentration evolution in a coupled atmosphere-ocean-sea ice model

    Science.gov (United States)

    Shi, Xiaoxu; Lohmann, Gerrit

    2017-09-01

    A coupled atmosphere-ocean-sea ice model is applied to investigate to what degree the area-thickness distribution of new ice formed in open water affects the ice and ocean properties. Two sensitivity experiments are performed which modify the horizontal-to-vertical aspect ratio of open-water ice growth. The resulting changes in the Arctic sea-ice concentration strongly affect the surface albedo, the ocean heat release to the atmosphere, and the sea-ice production. The changes are further amplified through a positive feedback mechanism among the Arctic sea ice, the Atlantic Meridional Overturning Circulation (AMOC), and the surface air temperature in the Arctic, as the Fram Strait sea ice import influences the freshwater budget in the North Atlantic Ocean. Anomalies in sea-ice transport lead to changes in sea surface properties of the North Atlantic and the strength of AMOC. For the Southern Ocean, the most pronounced change is a warming along the Antarctic Circumpolar Current (ACC), owing to the interhemispheric bipolar seasaw linked to AMOC weakening. Another insight of this study lies on the improvement of our climate model. The ocean component FESOM is a newly developed ocean-sea ice model with an unstructured mesh and multi-resolution. We find that the subpolar sea-ice boundary in the Northern Hemisphere can be improved by tuning the process of open-water ice growth, which strongly influences the sea ice concentration in the marginal ice zone, the North Atlantic circulation, salinity and Arctic sea ice volume. Since the distribution of new ice on open water relies on many uncertain parameters and the knowledge of the detailed processes is currently too crude, it is a challenge to implement the processes realistically into models. Based on our sensitivity experiments, we conclude a pronounced uncertainty related to open-water sea ice growth which could significantly affect the climate system sensitivity.

  9. The Response of Ice Sheets to Climate Variability

    Science.gov (United States)

    Snow, K.; Goldberg, D. N.; Holland, P. R.; Jordan, J. R.; Arthern, R. J.; Jenkins, A.

    2017-12-01

    West Antarctic Ice Sheet loss is a significant contributor to sea level rise. While the ice loss is thought to be triggered by fluctuations in oceanic heat at the ice shelf bases, ice sheet response to ocean variability remains poorly understood. Using a synchronously coupled ice-ocean model permitting grounding line migration, this study evaluates the response of an ice sheet to periodic variations in ocean forcing. Resulting oscillations in grounded ice volume amplitude is shown to grow as a nonlinear function of ocean forcing period. This implies that slower oscillations in climatic forcing are disproportionately important to ice sheets. The ice shelf residence time offers a critical time scale, above which the ice response amplitude is a linear function of ocean forcing period and below which it is quadratic. These results highlight the sensitivity of West Antarctic ice streams to perturbations in heat fluxes occurring at decadal time scales.

  10. Total energy cycle assessment of electric and conventional vehicles: an energy and environmental analysis. Volume 2: appendices A-D to technical report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-01-01

    This report compares the energy use, oil use and emissions of electric vehicles (EVs) with those of conventional, gasoline- powered vehicles (CVs) over the total life cycle of the vehicles. The various stages included in the vehicles` life cycles include vehicle manufacture, fuel production, and vehicle operation. Disposal is not included. An inventory of the air emissions associated with each stage of the life cycle is estimated. Water pollutants and solid wastes are reported for individual processes, but no comprehensive inventory is developed. Volume II contains additional details on the vehicle, utility, and materials analyses and discusses several details of the methodology.

  11. Exercise order affects the total training volume and the ratings of perceived exertion in response to a super-set resistance training session

    Directory of Open Access Journals (Sweden)

    Balsamo S

    2012-02-01

    Full Text Available Sandor Balsamo1–3, Ramires Alsamir Tibana1,2,4, Dahan da Cunha Nascimento1,2, Gleyverton Landim de Farias1,2, Zeno Petruccelli1,2, Frederico dos Santos de Santana1,2, Otávio Vanni Martins1,2, Fernando de Aguiar1,2, Guilherme Borges Pereira4, Jéssica Cardoso de Souza4, Jonato Prestes41Department of Physical Education, Centro Universitário UNIEURO, Brasília, 2GEPEEFS (Resistance training and Health Research Group, Brasília/DF, 3Graduate Program in Medical Sciences, School of Medicine, Universidade de Brasília (UnB, Brasília, 4Graduation Program in Physical Education, Catholic University of Brasilia (UCB, Brasília/DF, BrazilAbstract: The super-set is a widely used resistance training method consisting of exercises for agonist and antagonist muscles with limited or no rest interval between them – for example, bench press followed by bent-over rows. In this sense, the aim of the present study was to compare the effects of different super-set exercise sequences on the total training volume. A secondary aim was to evaluate the ratings of perceived exertion and fatigue index in response to different exercise order. On separate testing days, twelve resistance-trained men, aged 23.0 ± 4.3 years, height 174.8 ± 6.75 cm, body mass 77.8 ± 13.27 kg, body fat 12.0% ± 4.7%, were submitted to a super-set method by using two different exercise orders: quadriceps (leg extension + hamstrings (leg curl (QH or hamstrings (leg curl + quadriceps (leg extension (HQ. Sessions consisted of three sets with a ten-repetition maximum load with 90 seconds rest between sets. Results revealed that the total training volume was higher for the HQ exercise order (P = 0.02 with lower perceived exertion than the inverse order (P = 0.04. These results suggest that HQ exercise order involving lower limbs may benefit practitioners interested in reaching a higher total training volume with lower ratings of perceived exertion compared with the leg extension plus leg curl

  12. Total energy cycle assessment of electric and conventional vehicles: an energy and environmental analysis. Volume 4: peer review comments on technical report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-01-01

    This report compares the energy use, oil use and emissions of electric vehicles (EVs) with those of conventional, gasoline-powered vehicles (CVs) over the total life cycle of the vehicles. The various stages included in the vehicles` life cycles include vehicle manufacture, fuel production, and vehicle operation. Disposal is not included. An inventory of the air emissions associated with each stage of the life cycle is estimated. Water pollutants and solid wastes are reported for individual processes, but no comprehensive inventory is developed. Volume IV includes copies of all the external peer review comments on the report distributed for review in July 1997.

  13. Arctic multiyear ice classification and summer ice cover using passive microwave satellite data

    Science.gov (United States)

    Comiso, J. C.

    1990-08-01

    The ability to classify and monitor Arctic multiyear sea ice cover using multispectral passive microwave data is studied. Sea ice concentration maps during several summer minima have been analyzed to obtain estimates of ice surviving the summer. The results are compared with multiyear ice concentrations derived from data the following winter, using an algorithm that assumes a certain emissivity for multiyear ice. The multiyear ice cover inferred from the winter data is approximately 25 to 40% less than the summer ice cover minimum, suggesting that even during winter when the emissivity of sea ice is most stable, passive microwave data may account for only a fraction of the total multiyear ice cover. The difference of about 2×106 km2 is considerably more than estimates of advection through Fram Strait during the intervening period. It appears that as in the Antarctic, some multiyear ice floes in the Arctic, especially those near the summer marginal ice zone, have first-year ice or intermediate signatures in the subsequent winter. A likely mechanism for this is the intrusion of seawater into the snow-ice interface, which often occurs near the marginal ice zone or in areas where snow load is heavy. Spatial variations in melt and melt ponding effects also contribute to the complexity of the microwave emissivity of multiyear ice. Hence the multiyear ice data should be studied in conjunction with the previous summer ice data to obtain a more complete characterization of the state of the Arctic ice cover. The total extent and actual areas of the summertime Arctic pack ice were estimated to be 8.4×106 km2 and 6.2×106 km2, respectively, and exhibit small interannual variability during the years 1979 through 1985, suggesting a relatively stable ice cover.

  14. Blood parasites, total plasma protein and packed cell volume of small wild mammals trapped in three mountain ranges of the Atlantic Forest in Southeastern Brazil

    Directory of Open Access Journals (Sweden)

    MAML. Silva

    Full Text Available A study of blood parasites in small wild non-flying mammals was undertaken in three areas of the Atlantic Forest in Southeastern Brazil: Serra de Itatiaia, RJ, Serra da Bocaina, SP and Serra da Fartura, SP, from June 1999 to May 2001. A total of 450 animals (15 species were captured in traps and it was observed in 15.5% of the blood smears the presence of Haemobartonella sp. and Babesia sp. in red blood cells. There was no statistically significant difference between parasited and non-parasited specimens regarding total plasma protein, packed cell volume and body weight, which strongly suggests that these specimens might be parasite reservoirs.

  15. Enhanced adsorption of benzene vapor on granular activated carbon under humid conditions due to shifts in hydrophobicity and total micropore volume.

    Science.gov (United States)

    Liu, Han-Bing; Yang, Bing; Xue, Nan-Dong

    2016-11-15

    A series of hydrophobic-modified (polydimethylsiloxane (PDMS) coating) activated carbons (ACs) were developed to answer a fundamental question: what are the determinants that dominate the adsorption on ACs under humid conditions? Using column experiments, an inter-comparison among bare-AC and PDMS-coated ACs was conducted regarding the association of surface characteristics and adsorption capacity. Primary outcomes occurred in two dominating markers, hydrophobicity and total micropore volume, which played a key role in water adsorption on ACs. However, their contributions to water adsorption on ACs substantially differed under different Pwater/Pair conditions. Hydrophobicity was the only contributor in Pwater/Pair=0.1-0.6, while the two markers contributed equally in Pwater/Pair=0.7-1.0. Furthermore, PDMS-coated AC had a significant increase in benzene adsorption capacities compared to bare-AC at 0-90% relative humidity, while these differences were not significant among PDMS-coated ACs. It is thus presumed that the balance between the two markers can be shifted to favor almost unchanged benzene adsorption capacities among PDMS-coated ACs over a large range of relative humidity. These findings suggest potential benefits of PDMS coating onto ACs in enhancing selective adsorption of hydrophobic volatile organic compounds under high humid conditions. To develop new porous materials with both high total micropore volume and hydrophobicity should thus be considered. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Climate Impacts of Ice Nucleation

    Science.gov (United States)

    Gettelman, Andrew; Liu, Xiaohong; Barahona, Donifan; Lohmann, Ulrike; Chen, Celia

    2012-01-01

    Several different ice nucleation parameterizations in two different General Circulation Models (GCMs) are used to understand the effects of ice nucleation on the mean climate state, and the Aerosol Indirect Effects (AIE) of cirrus clouds on climate. Simulations have a range of ice microphysical states that are consistent with the spread of observations, but many simulations have higher present-day ice crystal number concentrations than in-situ observations. These different states result from different parameterizations of ice cloud nucleation processes, and feature different balances of homogeneous and heterogeneous nucleation. Black carbon aerosols have a small (0.06 Wm(exp-2) and not statistically significant AIE when included as ice nuclei, for nucleation efficiencies within the range of laboratory measurements. Indirect effects of anthropogenic aerosols on cirrus clouds occur as a consequence of increasing anthropogenic sulfur emissions with different mechanisms important in different models. In one model this is due to increases in homogeneous nucleation fraction, and in the other due to increases in heterogeneous nucleation with coated dust. The magnitude of the effect is the same however. The resulting ice AIE does not seem strongly dependent on the balance between homogeneous and heterogeneous ice nucleation. Regional effects can reach several Wm2. Indirect effects are slightly larger for those states with less homogeneous nucleation and lower ice number concentration in the base state. The total ice AIE is estimated at 0.27 +/- 0.10 Wm(exp-2) (1 sigma uncertainty). This represents a 20% offset of the simulated total shortwave AIE for ice and liquid clouds of 1.6 Wm(sup-2).

  17. Field research on using oil herding surfactants to thicken oil slicks in pack ice for in-situ burning. Volume 1

    International Nuclear Information System (INIS)

    Buist, I.; Potter, S.; Nedwed, T.; Mullin, J.

    2007-01-01

    Laboratory and field studies have been performed in recent years to determine the capability of herding agents to thicken oil slicks among loose pack ice for the purpose of in situ burning. In loose pack ice conditions where booms are not practical, effective in situ burns may be possible if thin slicks could be thickened to the 2 to 5 mm range. However, specific chemical surface-active agents known as herders are need to clear and contain oil slicks on an open water surface. The agents spread quickly over a water surface into a monomolecular layer due to their high spreading coefficients. The best agents have spreading pressures in the mid 40 mN/m range. As such, only small quantities of these surfactants are needed to clear thin films of oil from large areas of water surface, and to contract it into thicker slicks. This paper summarized the previous studies that evaluated shoreline-cleaning agents with oil herding properties. However, the main focus of this paper was on the final phase of testing conducted at the Prudhoe Bay Fire Training Grounds in November 2006 in which a series of outdoor burns were conducted at the scale of 30 m 2 with herders and crude oil in a test pool containing pieces of ice. The tests revealed that when a herder was used on crude oil slicks that were otherwise unignitable, the slicks could be ignited and burned in situ in brash and slush ice conditions at temperatures as low as -17 degrees C. Both the removal rate and efficiencies for the herded slicks were comparable to the theoretical maximum achievable for mechanically contained slicks on open water. 13 refs., 1 tab., 18 figs

  18. Resistance Training with Single vs. Multi-joint Exercises at Equal Total Load Volume: Effects on Body Composition, Cardiorespiratory Fitness, and Muscle Strength.

    Science.gov (United States)

    Paoli, Antonio; Gentil, Paulo; Moro, Tatiana; Marcolin, Giuseppe; Bianco, Antonino

    2017-01-01

    The present study aimed to compare the effects of equal-volume resistance training performed with single-joint (SJ) or multi-joint exercises (MJ) on VO 2 max, muscle strength and body composition in physically active males. Thirty-six participants were divided in two groups: SJ group ( n = 18, 182.1 ± 5.2, 80.03 ± 2.78 kg, 23.5 ± 2.7 years) exercised with only SJ exercises (e.g., dumbbell fly, knee extension, etc.) and MJ group ( n = 18, 185.3 ± 3.6 cm, 80.69 ± 2.98 kg, 25.5 ± 3.8 years) with only MJ exercises (e.g., bench press, squat, etc.). The total work volume (repetitions × sets × load) was equated between groups. Training was performed three times a week for 8 weeks. Before and after the training period, participants were tested for VO 2 max, body composition, 1 RM on the bench press, knee extension and squat. Analysis of covariance (ANCOVA) was used to compare post training values between groups, using baseline values as covariates. According to the results, both groups decreased body fat and increased fat free mass with no difference between them. Whilst both groups significantly increased cardiorespiratory fitness and maximal strength, the improvements in MJ group were higher than for SJ in VO 2 max (5.1 and 12.5% for SJ and MJ), bench press 1 RM (8.1 and 10.9% for SJ and MJ), knee extension 1 RM (12.4 and 18.9% for SJ and MJ) and squat 1 RM (8.3 and 13.8% for SJ and MJ). In conclusion, when total work volume was equated, RT programs involving MJ exercises appear to be more efficient for improving muscle strength and maximal oxygen consumption than programs involving SJ exercises, but no differences were found for body composition.

  19. Assessment of treatment response by total tumor volume and global apparent diffusion coefficient using diffusion-weighted MRI in patients with metastatic bone disease: a feasibility study.

    Directory of Open Access Journals (Sweden)

    Matthew D Blackledge

    Full Text Available We describe our semi-automatic segmentation of whole-body diffusion-weighted MRI (WBDWI using a Markov random field (MRF model to derive tumor total diffusion volume (tDV and associated global apparent diffusion coefficient (gADC; and demonstrate the feasibility of using these indices for assessing tumor burden and response to treatment in patients with bone metastases. WBDWI was performed on eleven patients diagnosed with bone metastases from breast and prostate cancers before and after anti-cancer therapies. Semi-automatic segmentation incorporating a MRF model was performed in all patients below the C4 vertebra by an experienced radiologist with over eight years of clinical experience in body DWI. Changes in tDV and gADC distributions were compared with overall response determined by all imaging, tumor markers and clinical findings at serial follow up. The segmentation technique was possible in all patients although erroneous volumes of interest were generated in one patient because of poor fat suppression in the pelvis, requiring manual correction. Responding patients showed a larger increase in gADC (median change = +0.18, range = -0.07 to +0.78 × 10(-3 mm2/s after treatment compared to non-responding patients (median change = -0.02, range = -0.10 to +0.05 × 10(-3 mm2/s, p = 0.05, Mann-Whitney test, whereas non-responding patients showed a significantly larger increase in tDV (median change = +26%, range = +3 to +284% compared to responding patients (median change = -50%, range = -85 to +27%, p = 0.02, Mann-Whitney test. Semi-automatic segmentation of WBDWI is feasible for metastatic bone disease in this pilot cohort of 11 patients, and could be used to quantify tumor total diffusion volume and median global ADC for assessing response to treatment.

  20. CICE, The Los Alamos Sea Ice Model

    Energy Technology Data Exchange (ETDEWEB)

    2017-05-12

    The Los Alamos sea ice model (CICE) is the result of an effort to develop a computationally efficient sea ice component for a fully coupled atmosphere–land–ocean–ice global climate model. It was originally designed to be compatible with the Parallel Ocean Program (POP), an ocean circulation model developed at Los Alamos National Laboratory for use on massively parallel computers. CICE has several interacting components: a vertical thermodynamic model that computes local growth rates of snow and ice due to vertical conductive, radiative and turbulent fluxes, along with snowfall; an elastic-viscous-plastic model of ice dynamics, which predicts the velocity field of the ice pack based on a model of the material strength of the ice; an incremental remapping transport model that describes horizontal advection of the areal concentration, ice and snow volume and other state variables; and a ridging parameterization that transfers ice among thickness categories based on energetic balances and rates of strain. It also includes a biogeochemical model that describes evolution of the ice ecosystem. The CICE sea ice model is used for climate research as one component of complex global earth system models that include atmosphere, land, ocean and biogeochemistry components. It is also used for operational sea ice forecasting in the polar regions and in numerical weather prediction models.

  1. Characterizing Arctic Sea Ice Topography Using High-Resolution IceBridge Data

    Science.gov (United States)

    Petty, Alek; Tsamados, Michel; Kurtz, Nathan; Farrell, Sinead; Newman, Thomas; Harbeck, Jeremy; Feltham, Daniel; Richter-Menge, Jackie

    2016-01-01

    We present an analysis of Arctic sea ice topography using high resolution, three-dimensional, surface elevation data from the Airborne Topographic Mapper, flown as part of NASA's Operation IceBridge mission. Surface features in the sea ice cover are detected using a newly developed surface feature picking algorithm. We derive information regarding the height, volume and geometry of surface features from 2009-2014 within the Beaufort/Chukchi and Central Arctic regions. The results are delineated by ice type to estimate the topographic variability across first-year and multi-year ice regimes.

  2. We Scream for Nano Ice Cream

    Science.gov (United States)

    Jones, M. Gail; Krebs, Denise L.; Banks, Alton J.

    2011-01-01

    There is a wide range of new products emerging from nanotechnology, and "nano ice cream" is an easy one that you can use to teach topics from surface area to volume applications. In this activity, students learn how ice cream can be made smoother and creamier tasting through nanoscience. By using liquid nitrogen to cool the cream mixture, students…

  3. Water, ice and mud: Lahars and lahar hazards at ice- and snow-clad volcanoes

    Science.gov (United States)

    Waythomas, Christopher F.

    2014-01-01

    Large-volume lahars are significant hazards at ice and snow covered volcanoes. Hot eruptive products produced during explosive eruptions can generate a substantial volume of melt water that quickly evolves into highly mobile flows of ice, sediment and water. At present it is difficult to predict the size of lahars that can form at ice and snow covered volcanoes due to their complex flow character and behaviour. However, advances in experiments and numerical approaches are producing new conceptual models and new methods for hazard assessment. Eruption triggered lahars that are ice-dominated leave behind thin, almost unrecognizable sedimentary deposits, making them likely to be under-represented in the geological record.

  4. Analysis of the total system life cycle cost for the Civilian Radioactive Waste Management Program: Volume 1, The analysis and its results

    International Nuclear Information System (INIS)

    1987-06-01

    This report provides cost estimates for the fifth evaluation of the adequacy of the fee and is consistent with the program strategy and plans. The total-system cost for the reference cases in the improved-performance system is estimated at $32.1 to $38.2 billion (expressed in constant 1986 dollars) over the entire life of the system...or $1.5 to $1.6 billion more than that of the authorized system (i.e., the system without an MRS facility). The current estimate of the total-system cost for the reference cases in the improved-performance system is $3.8 to $5.4 billion higher than the estimate for the same system in the 1986 TSLCC analysis. In the case with the maximum increase, nearly all of the higher cost is due to a $5.2-billion increase in the costs of development and evaluation (D and E); all other system costs are essentially unchanged. The cost difference between the improved-performance system and the authorized system is smaller than the difference estimated in last year's TSLCC analysis. Volume 2 presents the detailed results for the 1987 analysis of the total-system life cycle cost (TSLCC). It consists of four sections: Section A presents the yearly flows of waste between waste-management facilities for the 12 aggregate logistics cases that were studied; Section B presents the annual total-system costs for each of the 30 TSLCC cases by major cost category; Section C presents the annual costs for the disposal of 16,000 canisters of defense high-level waste (DHLW) by major cost category for each of the 30 TSLCC cases; and Section D presents a summary of the cost-allocation factors that were calculated to determine the defense waste share of the total-system costs

  5. Controlled ice nucleation using freeze-dried Pseudomonas syringae encapsulated in alginate beads.

    Science.gov (United States)

    Weng, Lindong; Tessier, Shannon N; Swei, Anisa; Stott, Shannon L; Toner, Mehmet

    2017-04-01

    The control of ice nucleation is of fundamental significance in many process technologies related to food and pharmaceutical science and cryobiology. Mechanical perturbation, electromagnetic fields and ice-nucleating agents (INAs) have been known to induce ice nucleation in a controlled manner. But these ice-nucleating methods may suffer from cumbersome manual operations, safety concerns of external fields, and biocompatibility and recovery issues of INA particles, especially when used in living systems. Given the automatic ice-seeding nature of INAs, a promising solution to overcome some of the above limitations is to engineer a biocomposite that accommodates the INA particles but minimizes their interactions with biologics, as well as enabling the recovery of used particles. In this study, freeze-dried Pseudomonas syringae, a model ice-nucleating agent, was encapsulated into microliter-sized alginate beads. We evaluated the performance of the bacterial hydrogel beads to initiate ice nucleation in water and aqueous glycerol solution by investigating factors including the size and number of the beads and the local concentration of INA particles. In the aqueous sample of a fixed volume, the total mass of the INA particles (m) was found to be the governing parameter that is solely responsible for determining the ice nucleation performance of the bacterial hydrogel beads. The freezing temperature has a strong positive linear correlation with log 10 m. The findings in this study provide an effective, predictable approach to control ice nucleation, which can improve the outcome and standardization of many ice-assisted process technologies. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. Arctic Ice Dynamics Joint Experiment (AIDJEX) 1975-1976, Physical Oceanography Data Report Profiling Current Meter Data -- Camp Caribou. Volume 1.

    Science.gov (United States)

    1980-02-01

    base of the ice. Hourly averages pertaining to the fixed-mast current meters can be obtained through the National Oceano - graphic Data Center. The...431 441 451 461 471 481 49t 50 40 ’II 421 431 441 󈧷j 461 4󈨋 481 491 Sol , 71ME :N :AYs Fig’ure 11. Speed and direction plotted for the manned AIDJEX...EDDIES Swift mesoscale undercurrents are one of the most notable oceano - graphic features observed in the AIDJEX area of the Arctic Ocean. The eddy form

  7. Radiative properties of ice clouds

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, D.L.; Koracin, D.; Carter, E. [Desert Research Institute, Reno, NV (United States)

    1996-04-01

    A new treatment of cirrus cloud radiative properties has been developed, based on anomalous diffraction theory (ADT), which does not parameterize size distributions in terms of an effective radius. Rather, is uses the size distribution parameters directly, and explicitly considers the ice particle shapes. There are three fundamental features which characterize this treatment: (1) the ice path radiation experiences as it travels through an ice crystal is parameterized, (2) only determines the amount of radiation scattered and absorbed, and (3) as in other treatments, the projected area of the size distribution is conserved. The first two features are unique to this treatment, since it does not convert the ice particles into equivalent volume or area spheres in order to apply Mie theory.

  8. Re-irradiation after gross total resection of recurrent glioblastoma. Spatial pattern of recurrence and a review of the literature as a basis for target volume definition

    Energy Technology Data Exchange (ETDEWEB)

    Straube, Christoph; Elpula, Greeshma [Technische Universitaet Muenchen (TUM), Department of Radiation Oncology, Klinikum rechts der Isar, Muenchen (Germany); Gempt, Jens; Gerhardt, Julia; Meyer, Bernhard [Technische Universitaet Muenchen (TUM), Department of Neurosurgery, Klinikum rechts der Isar, Muenchen (Germany); Bette, Stefanie; Zimmer, Claus [Technische Universitaet Muenchen (TUM), Department of Neuroradiology, Klinikum rechts der Isar, Muenchen (Germany); Schmidt-Graf, Friederike [Technische Universitaet Muenchen (TUM), Department of Neurology, Klinikum rechts der Isar, Muenchen (Germany); Combs, Stephanie E. [Technische Universitaet Muenchen (TUM), Department of Radiation Oncology, Klinikum rechts der Isar, Muenchen (Germany); Helmholtz Zentrum Muenchen, Institute for Innovative Radiotherapy (iRT), Department of Radiation Sciences (DRS), Oberschleissheim (Germany)

    2017-11-15

    Currently, patients with gross total resection (GTR) of recurrent glioblastoma (rGBM) undergo adjuvant chemotherapy or are followed up until progression. Re-irradiation, as one of the most effective treatments in macroscopic rGBM, is withheld in this situation, as uncertainties about the pattern of re-recurrence, the target volume, and also the efficacy of early re-irradiation after GTR exist. Imaging and clinical data from 26 consecutive patients with GTR of rGBM were analyzed. The spatial pattern of recurrences was analyzed according to the RANO-HGG criteria (''response assessment in neuro-oncology criteria for high-grade gliomas''). Progression-free (PFS) and overall survival (OS) were analyzed by the Kaplan-Meier method. Furthermore, a systematic review was performed in PubMed. All but 4 patients underwent adjuvant chemotherapy after GTR. Progression was diagnosed in 20 of 26 patients and 70% of recurrent tumors occurred adjacent to the resection cavity. The median extension beyond the edge of the resection cavity was 20 mm. Median PFS was 6 months; OS was 12.8 months. We propose a target volume containing the resection cavity and every contrast enhancing lesion as the gross tumor volume (GTV), a spherical margin of 5-10 mm to generate the clinical target volume (CTV), and a margin of 1-3 mm to generate the planning target volume (PTV). Re-irradiation of this volume is deemed to be safe and likely to prolong PFS. Re-irradiation is worth considering also after GTR, as the volumes that need to be treated are limited and re-irradiation has already proven to be a safe treatment option in general. The strategy of early re-irradiation is currently being tested within the GlioCave/NOA 17/Aro 2016/03 trial. (orig.) [German] Patienten mit einem rezidivierten Glioblastom (rGBM) werden, wenn eine komplette Resektion (GTR) des makroskopischen Rezidivs durchgefuehrt wurde, aktuell meist systemisch adjuvant behandelt oder einer engmaschigen Nachsorge

  9. High-throughput analysis using non-depletive SPME: challenges and applications to the determination of free and total concentrations in small sample volumes.

    Science.gov (United States)

    Boyacı, Ezel; Bojko, Barbara; Reyes-Garcés, Nathaly; Poole, Justen J; Gómez-Ríos, Germán Augusto; Teixeira, Alexandre; Nicol, Beate; Pawliszyn, Janusz

    2018-01-18

    In vitro high-throughput non-depletive quantitation of chemicals in biofluids is of growing interest in many areas. Some of the challenges facing researchers include the limited volume of biofluids, rapid and high-throughput sampling requirements, and the lack of reliable methods. Coupled to the above, growing interest in the monitoring of kinetics and dynamics of miniaturized biosystems has spurred the demand for development of novel and revolutionary methodologies for analysis of biofluids. The applicability of solid-phase microextraction (SPME) is investigated as a potential technology to fulfill the aforementioned requirements. As analytes with sufficient diversity in their physicochemical features, nicotine, N,N-Diethyl-meta-toluamide, and diclofenac were selected as test compounds for the study. The objective was to develop methodologies that would allow repeated non-depletive sampling from 96-well plates, using 100 µL of sample. Initially, thin film-SPME was investigated. Results revealed substantial depletion and consequent disruption in the system. Therefore, new ultra-thin coated fibers were developed. The applicability of this device to the described sampling scenario was tested by determining the protein binding of the analytes. Results showed good agreement with rapid equilibrium dialysis. The presented method allows high-throughput analysis using small volumes, enabling fast reliable free and total concentration determinations without disruption of system equilibrium.

  10. L-band radiometry for sea ice applications

    Science.gov (United States)

    Heygster, G.; Hedricks, S.; Mills, P.; Kaleschke, L.; Stammer, D.; Tonboe, R.

    2009-04-01

    Although sea ice remote sensing has reached the level of operational exploitation with well established retrieval methods, several important tasks are still unsolved. In particular during freezing and melting periods with mixed ice and water surfaces, estimates of ice concentration with passive and active microwave sensors remain challenging. Newly formed thin ice is also hard to distinguish from open water with radiometers for frequencies above 8 GHz. The SMOS configuration (planned launch 2009) with a radiometer at 1.4 GHz is a promising technique to complement observations at higher microwave frequencies. ESA has initiated a project to investigate the possibilities for an additional Level-2 sea ice data product based on SMOS. In detail, the project objectives are (1) to model the L band emission of sea ice, and to assess the potential (2) to retrieve sea ice parameters, especially concentration and thickness, and (3) to use cold water regions for an external calibration of SMOS. Modelling of L band emission: Several models have are investigated. All of them work on the same basic principles and have a vertically-layered, plane-parallel geometry. They are comprised of three basic components: (1) effective permittivities are calculated for each layer based on ice bulk and micro-structural properties; (2) these are integrated across the total depth to derive emitted brightness temperature; (3) scattering terms can also be added because of the granular structure of ice and snow. MEMLS (Microwave Emission Model of Layered Snowpacks (Wiesmann and Matzler 1999)) is one such model that contains all three elements in a single Matlab program. In the absence of knowledge about the internal structure of the sea ice, three-layer (air, ice and water) dielectric slab models which take as input a single effective permittivity for the ice layer are appropriate. By ignoring scattering effects one can derive a simple analytic expression for a dielectric slab as shown by Apinis and

  11. Resistance Training with Single vs. Multi-joint Exercises at Equal Total Load Volume: Effects on Body Composition, Cardiorespiratory Fitness, and Muscle Strength

    Directory of Open Access Journals (Sweden)

    Antonio Paoli

    2017-12-01

    Full Text Available The present study aimed to compare the effects of equal-volume resistance training performed with single-joint (SJ or multi-joint exercises (MJ on VO2max, muscle strength and body composition in physically active males. Thirty-six participants were divided in two groups: SJ group (n = 18, 182.1 ± 5.2, 80.03 ± 2.78 kg, 23.5 ± 2.7 years exercised with only SJ exercises (e.g., dumbbell fly, knee extension, etc. and MJ group (n = 18, 185.3 ± 3.6 cm, 80.69 ± 2.98 kg, 25.5 ± 3.8 years with only MJ exercises (e.g., bench press, squat, etc.. The total work volume (repetitions × sets × load was equated between groups. Training was performed three times a week for 8 weeks. Before and after the training period, participants were tested for VO2max, body composition, 1 RM on the bench press, knee extension and squat. Analysis of covariance (ANCOVA was used to compare post training values between groups, using baseline values as covariates. According to the results, both groups decreased body fat and increased fat free mass with no difference between them. Whilst both groups significantly increased cardiorespiratory fitness and maximal strength, the improvements in MJ group were higher than for SJ in VO2max (5.1 and 12.5% for SJ and MJ, bench press 1 RM (8.1 and 10.9% for SJ and MJ, knee extension 1 RM (12.4 and 18.9% for SJ and MJ and squat 1 RM (8.3 and 13.8% for SJ and MJ. In conclusion, when total work volume was equated, RT programs involving MJ exercises appear to be more efficient for improving muscle strength and maximal oxygen consumption than programs involving SJ exercises, but no differences were found for body composition.

  12. Heavy Metal Presence in Two Different Types of Ice Cream: Artisanal Ice Cream (Italian Gelato) and Industrial Ice Cream.

    Science.gov (United States)

    Conficoni, D; Alberghini, L; Bissacco, E; Ferioli, M; Giaccone, V

    2017-03-01

    Ice cream, a popular product worldwide, is usually a milk-based product with other types of ingredients (fruit, eggs, cocoa, dried fruit, additives, and others). Different materials are used to obtain the desired taste, texture, consistency, and appearance of the final product. This study surveyed ice cream products available in Italy for heavy metals (lead, cadmium, chromium, tin, and arsenic). The differences between artisanal and industrial ice cream were also investigated because of the importance in the Italian diet and the diffusion of this ready-to-eat food. Ice cream sampling was performed between October 2010 and February 2011 in the northeast of Italy. A total of 100 samples were randomly collected from different sources: 50 industrial samples produced by 19 different brands were collected in coffee bars and supermarkets; 50 artisanal ice cream samples were gathered at nine different artisanal ice cream shops. Ten wooden sticks of industrial ice cream were analyzed in parallel to the ice cream. All samples were negative for arsenic and mercury. None of the artisanal ice cream samples were positive for lead and tin; 18% of the industrial ice cream samples were positive. All positive lead samples were higher than the legal limit stated for milk (0.02 mg/kg). All industrial ice cream samples were negative for cadmium, but cadmium was present in 10% of the artisanal ice cream samples. Chromium was found in 26% of the artisanal and in 58% of the industrial ice cream samples. The heavy metals found in the wooden sticks were different from the corresponding ice cream, pointing out the lack of cross-contamination between the products. Considering the results and the amount of ice cream consumed during the year, contamination through ice cream is a low risk for the Italian population, even though there is need for further analysis.

  13. Ice Ages

    Indian Academy of Sciences (India)

    that the precession of the earth's orbit caused ice ages. The precession of the earth's orbit leads to changes in the time of the year at which ... than in the southern hemisphere. ..... small increase in ocean temperature implies a large increase in.

  14. Contribution of Deformation to Sea Ice Mass Balance: A Case Study From an N-ICE2015 Storm

    Science.gov (United States)

    Itkin, Polona; Spreen, Gunnar; Hvidegaard, Sine Munk; Skourup, Henriette; Wilkinson, Jeremy; Gerland, Sebastian; Granskog, Mats A.

    2018-01-01

    The fastest and most efficient process of gaining sea ice volume is through the mechanical redistribution of mass as a consequence of deformation events. During the ice growth season divergent motion produces leads where new ice grows thermodynamically, while convergent motion fractures the ice and either piles the resultant ice blocks into ridges or rafts one floe under the other. Here we present an exceptionally detailed airborne data set from a 9 km2 area of first year and second year ice in the Transpolar Drift north of Svalbard that allowed us to estimate the redistribution of mass from an observed deformation event. To achieve this level of detail we analyzed changes in sea ice freeboard acquired from two airborne laser scanner surveys just before and right after a deformation event brought on by a passing low-pressure system. A linear regression model based on divergence during this storm can explain 64% of freeboard variability. Over the survey region we estimated that about 1.3% of level sea ice volume was pressed together into deformed ice and the new ice formed in leads in a week after the deformation event would increase the sea ice volume by 0.5%. As the region is impacted by about 15 storms each winter, a simple linear extrapolation would result in about 7% volume increase and 20% deformed ice fraction at the end of the season.

  15. Polarimetric SAR interferometry applied to land ice: modeling

    DEFF Research Database (Denmark)

    Dall, Jørgen; Papathanassiou, Konstantinos; Skriver, Henning

    2004-01-01

    This paper introduces a few simple scattering models intended for the application of polarimetric SAR interfer-ometry to land ice. The principal aim is to eliminate the penetration bias hampering ice sheet elevation maps generated with single-channel SAR interferometry. The polarimetric coherent...... scattering models are similar to the oriented-volume model and the random-volume-over-ground model used in vegetation studies, but the ice models are adapted to the different geometry of land ice. Also, due to compaction, land ice is not uniform; a fact that must be taken into account for large penetration...... depths. The validity of the scattering models is examined using L-band polarimetric interferometric SAR data acquired with the EMISAR system over an ice cap located in the percolation zone of the Greenland ice sheet. Radar reflectors were deployed on the ice surface prior to the data acquisition in order...

  16. Optical properties of melting first-year Arctic sea ice

    Science.gov (United States)

    Light, Bonnie; Perovich, Donald K.; Webster, Melinda A.; Polashenski, Christopher; Dadic, Ruzica

    2015-11-01

    The albedo and transmittance of melting, first-year Arctic sea ice were measured during two cruises of the Impacts of Climate on the Eco-Systems and Chemistry of the Arctic Pacific Environment (ICESCAPE) project during the summers of 2010 and 2011. Spectral measurements were made for both bare and ponded ice types at a total of 19 ice stations in the Chukchi and Beaufort Seas. These data, along with irradiance profiles taken within boreholes, laboratory measurements of the optical properties of core samples, ice physical property observations, and radiative transfer model simulations are employed to describe representative optical properties for melting first-year Arctic sea ice. Ponded ice was found to transmit roughly 4.4 times more total energy into the ocean, relative to nearby bare ice. The ubiquitous surface-scattering layer and drained layer present on bare, melting sea ice are responsible for its relatively high albedo and relatively low transmittance. Light transmittance through ponded ice depends on the physical thickness of the ice and the magnitude of the scattering coefficient in the ice interior. Bare ice reflects nearly three-quarters of the incident sunlight, enhancing its resiliency to absorption by solar insolation. In contrast, ponded ice absorbs or transmits to the ocean more than three-quarters of the incident sunlight. Characterization of the heat balance of a summertime ice cover is largely dictated by its pond coverage, and light transmittance through ponded ice shows strong contrast between first-year and multiyear Arctic ice covers.

  17. Eulerian Method for Ice Crystal Icing

    NARCIS (Netherlands)

    Norde, Ellen; van der Weide, Edwin Theodorus Antonius; Hoeijmakers, Hendrik Willem Marie

    In this study, an ice accretion method aimed at ice crystal icing in turbofan engines is developed and demonstrated for glaciated as well as mixed-phase icing conditions. The particle trajectories are computed by an Eulerian trajectory method. The effects of heat transfer and phase change on the

  18. [Total brain T2-hyperintense lesion-volume and the axonal damage in the normal-appearing white matter of brainstem in early lapsing-remitting multiple sclerosis].

    Science.gov (United States)

    Pascual-Lozano, A M; Martínez-Bisbal, M C; Boscá-Blasco, I; Valero-Merino, C; Coret-Ferrer, F; Martí-Bonmatí, L; Martínez-Granados, B; Celda, B; Casanova-Estruch, B

    To evaluate the relationship between the total brain T2-hyperintense lesion volume (TBT2LV) and the axonal damage in the normal-appearing white matter of brainstem measured by 1H-MRS in a group of early relapsing-remitting multiple sclerosis patients. 40 relapsing-remitting multiple sclerosis patients and ten sex- and age-matched healthy subjects were prospectively studied for two years. T2-weighted MR and 1H-MRS imaging were acquired at time of recruitment and at year two. The TBT2LV was calculated with a semiautomatic program; N-acetylaspartate (NAA), creatine (Cr) and choline (Cho) resonances areas were integrated with jMRUI program and the ratios were calculated for four volume elements that represented the brainstem. At basal study we obtained an axonal loss (as a decrement of NAA/ Cho ratio) in the group of patients compared with controls (p = 0.017); this axonal loss increased at the second year of the follow-up for patients (NAA/Cho decrease, p = 0.004, and NAA/Cr decrease, p = 0.002) meanwhile control subjects had no significant metabolic changes. Higher lesion load was correlated with a poor clinical outcome, being the correlation between the basal TBT2LV and the Expanded Disability Status Scale at second year (r = 0.299; p = 0.05). Besides, axonal loss was not homogeneous for all multiple sclerosis patients, being stronger in the subgroup of patients with high basal TBT2LV (p = 0.043; ANOVA). Our data suggest that axonal damage is early in multiple sclerosis and higher in patients high basal TBT2LV, suggesting a possible relationship between these two phenomena.

  19. Transitioning to the direct anterior approach in total hip arthroplasty. Is it a true muscle sparing approach when performed by a low volume hip replacement surgeon?

    Science.gov (United States)

    Nistor, Dan-Viorel; Caterev, Sergiu; Bolboacă, Sorana-Daniela; Cosma, Dan; Lucaciu, Dan Osvald Gheorghe; Todor, Adrian

    2017-11-01

    We conducted this study to establish if the transition from a lateral approach (LA) to the direct anterior approach (DAA) for a low volume hip arthroplasty surgeon during the steep learning curve can be performed maintaining the muscle sparing approach of the DAA without increasing the complication rates. In this controlled, prospective, randomized clinical study we investigated 70 patients (35 DAA, 35 LA) with similar demographics that underwent a total hip arthroplasty. Assessment of the two approaches consisted of determining the invasiveness through serum markers for muscle damage (i.e. myoglobin, creatine kinase and lactate dehydrogenase), the operative parameters such as post-operative pain and rescue medication consumption, the component positioning and complication rates. Post-operative myoglobin levels were higher (p < 0.001) in the LA group (326.42 ± 84.91 ng/mL) as compared to the DAA group (242.80 ± 71.03 ng/mL), but with no differences regarding other biomarkers for muscle damage. Pain levels were overall lower in the DAA group, with a statistical and clinical difference during surgery day (p < 0.001) associated with lower (p < 0.001) rescue medication consumption (median 1 (1; 3) mg morphine vs. 3 (2; 4) mg morphine). Most patients in the LA group reported chronic post-operative pain throughout all three evaluated months, while the majority of patients in the DAA group reported no pain after week six. Component positioning did not differ significantly between groups and neither did complication rates. The DAA can be transitioned from the LA safely, without higher complication rates while maintaining its muscle spearing advantages when performed by a low volume hip arthroplasty surgeon.

  20. The Dependence of Cirrus Gamma Size Distributions Expressed as Volumes in N(sub 0)-Lambda-Mu Phase Space and Bulk Cloud Properties on Environmental Conditions: Results from the Small Ice Particles in Cirrus Experiment (SPARTICUS)

    Science.gov (United States)

    Jackson, Robert C.; McFarquhar, Greg M.; Fridlind, Ann M.; Atlas, Rachel

    2015-01-01

    The variability of cirrus ice microphysical properties is investigated using observations obtained during the Small Particles in Cirrus (SPARTICUS) campaign. An existing approach that represents a size distribution (SD) as a single gamma function using an ellipsoid of equally realizable solutions in (N(sub 0), lambda, mu) phase space is modified to automatically identify multiple modes in SDs and characterize each mode by such an ellipsoid. The modified approach is applied to ice crystals with maximum dimension D greater than15 micrometers collected by the 2-D stereo and 2-D precipitation probes on the Stratton Park Engineering Company Learjet. The dependencies of N(sub 0), mu, and lambda from each mode, total number concentration, bulk extinction, ice water content (IWC), and mass median maximum dimension D(sub mm) as a function of temperature T and cirrus type are then analyzed. The changes in the observed codependencies between N(sub 0), mu, and lambda, bulk extinction, IWC, and D(sub mm) with environmental conditions indicate that particles were larger at higher T during SPARTICUS. At most two modes were observed in any SD during SPARTICUS, with the average boundary between them at 115 micrometers, similar to past studies not using probes with shatter mitigating tips and artifact removal algorithms. The bimodality of the SDs increased with T. This and the differences in N(sub 0), mu, and lambda between the modes suggest that particles with smaller D nucleated more recently than particles with larger D, which grew via vapor deposition and aggregation. Because smaller crystals, whose concentrations are uncertain, make marginal contributions to higher order moments, the use of higher moments for evaluating model fields is suggested.

  1. Sea ice - Multiyear cycles and white ice

    Science.gov (United States)

    Ledley, T. S.

    1985-01-01

    The multiyear thickness cycles represent one of the interesting features of the sea ice studies performed by Semtner (1976) and Washington et al. (1976) with simple thermodynamic models of sea ice. In the present article, a description is given of results which show that the insulating effect of snow on the surface of the sea ice is important in producing these multiyear cycles given the physics included in the model. However, when the formation of white ice is included, the cycles almost disappear. White ice is the ice which forms at the snow-ice interface when the snow layer becomes thick enough to depress the ice below the water level. Water infiltrates the snow by coming through the ice at leads and generally freezes there, forming white ice.

  2. On the Predictability of Sea Ice

    Science.gov (United States)

    Blanchard-Wrigglesworth, Edward

    We investigate the persistence and predictability of sea ice in numerical models and observations. We first use the 3rd generation Community Climate System Model (CCSM3) General Circulation Model (GCM) to investigate the inherent persistence of sea-ice area and thickness. We find that sea-ice area anomalies have a seasonal decay timescale, exhibiting an initial decorrelation similar to a first order auto-regressive (AR1, or red noise) process. Beyond this initial loss of memory, there is a re-emergence of memory at certain times of the year. There are two distinct modes of re-emergence in the model, one driven by the seasonal coupling of area and thickness anomalies in the summer, the other by the persistence of upper ocean temperature anomalies that originate from ice anomalies in the melt season and then influence ice anomalies in the growth season. Comparison with satellite observations where available indicate these processes appear in nature. We then use the 4th generation CCSM (CCSM4) to investigate the partition of Arctic sea-ice predictability into its initial-value and boundary forced components under present day forcing conditions. We find that initial-value predictability lasts for 1-2 years for sea-ice area, and 3-4 years for sea-ice volume. Forced predictability arises after just 4-5 years for both area and volume. Initial-value predictability of sea-ice area during the summer hinges on the coupling between thickness and area anomalies during that season. We find that the loss of initial-value predictability with time is not uniform --- there is a rapid loss of predictability of sea-ice volume during the late spring early summer associated with snow melt and albedo feedbacks. At the same time, loss of predictability is not uniform across different regions. Given the usefulness of ice thickness as a predictor of summer sea-ice area, we obtain a hindcast of September sea-ice area initializing the GCM on May 1with an estimate of observed sea-ice thickness

  3. An empirical firn-densification model comprising ice-lences

    DEFF Research Database (Denmark)

    Reeh, Niels; Fisher, D.A.; Koerner, R.M.

    2005-01-01

    a suitable value of the surface snow density. In the present study, a simple densification model is developed that specifically accounts for the content of ice lenses in the snowpack. An annual layer is considered to be composed of an ice fraction and a firn fraction. It is assumed that all meltwater formed...... changes reflect a volume change of the ice sheet with no corresponding change of mass, i.e. a volume change that does not influence global sea level....

  4. Prognostic value of metabolic tumour volume and total lesion glycolysis in 18F-FDG PET/CT scans in locally advanced breast cancer staging.

    Science.gov (United States)

    Jiménez-Ballvé, A; García García-Esquinas, M; Salsidua-Arroyo, O; Serrano-Palacio, A; García-Sáenz, J A; Ortega Candil, A; Fuentes Ferrer, M E; Rodríguez Rey, C; Román-Santamaría, J M; Moreno, F; Carreras-Delgado, J L

    To determine whether metabolic tumour volume (MTV) and total lesion glycolysis (TLG) are able to predict recurrence risk in locally advanced breast cancer (LABC) patients. Retrospective study of LABC patients who undertook neoadjuvant, local and adjuvant treatment and follow up. A 18 F-FDG PET/CT study for initial staging was performed analysing in this study different metabolic parameters (MTV, TLG, SUVmax and SUVmed) both in the primary tumour (T) as well as in axillary nodes (N) and whole-body (WB). Forty females were included between January 2010-2011; follow up until January 2015 was completed. The average follow-up was 46 months. Twenty percent presented recurrence: local disease (n=2) and distant metastasis (n=6); 3 patients died (38% of the patients which recurred and 7.5% from the total). SUVmax, MTV and TLG, in T, N and WB, were higher in those patients with recurrence. The MTV and TLG parameters in the tumour (T) were related to the recurrence rate (P=.020 and P=.028, respectively); whereas SUVmax in the lymph nodes (N) was significantly related (P=.008) to the recurrence rate. The best cut-off points to predict recurrence where: MTV T ≥19.3cm 3 , TLG T≥74.4g and SUVmax N≥13.8, being 10-12 times more likely to recidivate when these thresholds where exceeded. Tumour grade was the only clinical-pathological variable which was related to recurrence probability (p=.035). In this study of LABC patients the metabolic parameters which have a better relationship with recurrence rate are: MTV and TLG in the primary tumour, SUVmax in the regional lymph node disease and whole-body PET data. Copyright © 2016 Elsevier España, S.L.U. y SEMNIM. All rights reserved.

  5. Implementation of a Total Hip Arthroplasty Care Pathway at a High-Volume Health System: Effect on Length of Stay, Discharge Disposition, and 90-Day Complications.

    Science.gov (United States)

    Featherall, Joseph; Brigati, David P; Faour, Mhamad; Messner, William; Higuera, Carlos A

    2018-06-01

    Standardized care pathways are evidence-based algorithms for optimizing an episode of care. Despite the theoretical promise of care pathways, there is an inconsistent literature demonstrating improvements in patient care. The authors hypothesized that implementing a care pathway, across 11 hospitals, would decrease hospital length of stay (LOS), decrease postoperative complications at 90 days, and increase discharges to home. A multidisciplinary team developed an evidence-based care pathway for total hip arthroplasty (THA) perioperative care. All patients receiving THA in 2013 (pre-protocol, historical control), 2014 (transition), and 2015 (full protocol implementation) were included in the analysis. Multivariable regression assessed the relationship of the care pathway to 90-day postoperative complications, LOS, and discharge disposition. Cost savings were estimated using previously published postarthroplasty episode and per diem hospital costs. A total of 6090 primary THAs were conducted during the study period. After adjusting for the covariates, the full protocol implementation was associated with a decrease in LOS (mean ratio, 0.747; 95% confidence interval [CI; 0.727, 0.767]) and an increase in discharges to home (odds ratio, 2.079; 95% CI [1.762, 2.456]). The full protocol implementation was not associated with a change in 90-day complications (odds ratio, 1.023; 95% CI [0.841, 1.245]). Payer-perspective-calculated theoretical cost savings, including both index admission and postdischarge costs, were $2533 per patient. The THA care pathway implementation was successful in reducing LOS and increasing discharges to home. The care pathway was not associated with a change in 90-day complications; further targeted interventions in this area are needed. Despite care standardization efforts, high-volume hospitals and surgeons had higher performance. Extrapolation of theoretical cost savings indicates that widespread THA care pathway adoption could lead to national

  6. Forecasting Turbine Icing Events

    DEFF Research Database (Denmark)

    Davis, Neil; Hahmann, Andrea N.; Clausen, Niels-Erik

    2012-01-01

    In this study, we present a method for forecasting icing events. The method is validated at two European wind farms in with known icing events. The icing model used was developed using current ice accretion methods, and newly developed ablation algorithms. The model is driven by inputs from the WRF...... mesoscale model, allowing for both climatological estimates of icing and short term icing forecasts. The current model was able to detect periods of icing reasonably well at the warmer site. However at the cold climate site, the model was not able to remove ice quickly enough leading to large ice...

  7. Modelo de predição para o volume total de Quaruba (Vochysia inundata ducke via análise de fatores e regressão

    Directory of Open Access Journals (Sweden)

    Mário Diego Rocha Valente

    2011-04-01

    Full Text Available Neste trabalho propôs-se um método para a construção de um modelo de regressão para determinar o Volume de Madeira Total da espécie florestal (Vochysia inundata ducke Quaruba, em função de suas características (Diâmetro à Altura do Peito (DAP, Idade e Altura. O modelo foi determinado utilizando-se a técnica estatística multivariada de Análise de Fatores com do Método das Componentes Principais via Rotação Ortogonal do Tipo Varimax para Extração dos Fatores, procurando contornar o problema da Multicolinearidade. Por fim desenvolveu-se um modelo de Regressão Linear Simples com base nos Escores Fatoriais. O modelo determinado apresentou-se de fácil interpretação e utilização, usando-se um fator e proporcionando um bom ajuste (R² = 96 % aos dados e uma boa capacidade preditiva. Ele atendeu a todas as suposições teóricas para sua existência e utilização.

  8. Adaptations to Short, Frequent Sessions of Endurance and Strength Training Are Similar to Longer, Less Frequent Exercise Sessions When the Total Volume Is the Same.

    Science.gov (United States)

    Kilen, Anders; Hjelvang, Line B; Dall, Niels; Kruse, Nanna L; Nordsborg, Nikolai B

    2015-11-01

    The hypothesis that the distribution of weekly training across several short sessions, as opposed to fewer longer sessions, enhances maximal strength gain without compromising maximal oxygen uptake was evaluated. Twenty-nine subjects completed an 8-week controlled parallel-group training intervention. One group ("micro training" [MI]: n = 21) performed nine 15-minute training sessions weekly, whereas a second group ("classical training" [CL]: n = 8) completed exactly the same training on a weekly basis but as three 45-minute sessions. For each group, each session comprised exclusively strength, high-intensity cardiovascular training or muscle endurance training. Both groups increased shuttle run performance (MI: 1,373 ± 133 m vs. 1,498 ± 126 m, p ≤ 0.05; CL: 1,074 ± 213 m vs. 1,451 ± 202 m, p training intervention. In conclusion, similar training adaptations can be obtained with short, frequent exercise sessions or longer, less frequent sessions where the total volume of weekly training performed is the same.

  9. Sintering and microstructure of ice: a review

    International Nuclear Information System (INIS)

    Blackford, Jane R

    2007-01-01

    Sintering of ice is driven by the thermodynamic requirement to decrease surface energy. The structural morphology of ice in nature has many forms-from snowflakes to glaciers. These forms and their evolution depend critically on the balance between the thermodynamic and kinetic factors involved. Ice is a crystalline material so scientific understanding and approaches from more conventional materials can be applied to ice. The early models of solid state ice sintering are based on power law models originally developed in metallurgy. For pressure sintering of ice, these are based on work on hot isostatic pressing of metals and ceramics. Recent advances in recognizing the grain boundary groove geometry between sintering ice particles require models that use new approaches in materials science. The newer models of sintering in materials science are beginning to incorporate more realistic processing conditions and microstructural complexity, and so there is much to be gained from applying these to ice in the future. The vapour pressure of ice is high, which causes it to sublime readily. The main mechanism for isothermal sintering of ice particles is by vapour diffusion; however other transport mechanisms certainly contribute. Plastic deformation with power law creep combined with recrystallization become important mechanisms in sintering with external pressure. Modern experimental techniques, low temperature scanning electron microscopy and x-ray tomography, are providing new insights into the evolution of microstructures in ice. Sintering in the presence of a small volume fraction of the liquid phase causes much higher bond growth rates. This may be important in natural snow which contains impurities that form a liquid phase. Knowledge of ice microstructure and sintering is beneficial in understanding mechanical behaviour in ice friction and the stability of snow slopes prone to avalanches. (topical review)

  10. Elevator deflections on the icing process

    Science.gov (United States)

    Britton, Randall K.

    1990-01-01

    The effect of elevator deflection of the horizontal stabilizer for certain icing parameters is investigated. Elevator deflection can severely change the lower and upper leading-edge impingement limits, and ice can accrete on the elevator itself. Also, elevator deflection had practically no effect on the maximum local collection efficiency. It is shown that for severe icing conditions (large water droplets), elevator deflections that increase the projected height of the airfoil can significantly increase the total collection efficiency of the airfoil.

  11. Variability and Trends in Sea Ice Extent and Ice Production in the Ross Sea

    Science.gov (United States)

    Comiso, Josefino; Kwok, Ronald; Martin, Seelye; Gordon, Arnold L.

    2011-01-01

    Salt release during sea ice formation in the Ross Sea coastal regions is regarded as a primary forcing for the regional generation of Antarctic Bottom Water. Passive microwave data from November 1978 through 2008 are used to examine the detailed seasonal and interannual characteristics of the sea ice cover of the Ross Sea and the adjacent Bellingshausen and Amundsen seas. For this period the sea ice extent in the Ross Sea shows the greatest increase of all the Antarctic seas. Variability in the ice cover in these regions is linked to changes in the Southern Annular Mode and secondarily to the Antarctic Circumpolar Wave. Over the Ross Sea shelf, analysis of sea ice drift data from 1992 to 2008 yields a positive rate of increase in the net ice export of about 30,000 sq km/yr. For a characteristic ice thickness of 0.6 m, this yields a volume transport of about 20 cu km/yr, which is almost identical, within error bars, to our estimate of the trend in ice production. The increase in brine rejection in the Ross Shelf Polynya associated with the estimated increase with the ice production, however, is not consistent with the reported Ross Sea salinity decrease. The locally generated sea ice enhancement of Ross Sea salinity may be offset by an increase of relatively low salinity of the water advected into the region from the Amundsen Sea, a consequence of increased precipitation and regional glacial ice melt.

  12. Basin-scale partitioning of Greenland ice sheet mass balance components (2007-2011)

    DEFF Research Database (Denmark)

    Andersen, M.L.; Stenseng, Lars; Skourup, Henriette

    2015-01-01

    The current deficit in Greenland ice sheet mass balance is due to both a decrease in surface mass balance (SMB) input and an increase in ice discharge (D) output. While SMB processes are beginning to be well captured by observationally-constrained climate modeling, insight into D is relatively...... of the gate. Using a 1961-1990 reference climatology SMB field from the MAR regional climate model, we quantify ice sheet mass balance within eighteen basins. We find a 2007-2011 mean D of 515±57 Gtyr-1. We find a 2007-2011 mean total mass balance of -262±21 Gtyr-1, which is equal to a 0.73 mm yr-1 global sea...... limited. We use InSAR-derived velocities, in combination with ice thickness observations, to quantify the mass flux (F) across a flux perimeter around the ice sheet at ~1700 m elevation. To quantify D, we correct F for SMB, as well as changes in volume due to ice dynamics, in the area downstream...

  13. Gas permeability of ice-templated, unidirectional porous ceramics

    Science.gov (United States)

    Seuba, Jordi; Deville, Sylvain; Guizard, Christian; Stevenson, Adam J.

    2016-01-01

    We investigate the gas flow behavior of unidirectional porous ceramics processed by ice-templating. The pore volume ranged between 54% and 72% and pore size between 2.9 ?m and 19.1 ?m. The maximum permeability (?? m?) was measured in samples with the highest total pore volume (72%) and pore size (19.1 ?m). However, we demonstrate that it is possible to achieve a similar permeability (?? m?) at 54% pore volume by modification of the pore shape. These results were compared with those reported and measured for isotropic porous materials processed by conventional techniques. In unidirectional porous materials tortuosity (?) is mainly controlled by pore size, unlike in isotropic porous structures where ? is linked to pore volume. Furthermore, we assessed the applicability of Ergun and capillary model in the prediction of permeability and we found that the capillary model accurately describes the gas flow behavior of unidirectional porous materials. Finally, we combined the permeability data obtained here with strength data for these materials to establish links between strength and permeability of ice-templated materials.

  14. Great Lakes Ice Charts

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Charts show ice extent and concentration three times weekly during the ice season, for all lakes except Ontario, from the 1973/74 ice season through the 2001/2002...

  15. Impact of increasing antarctic glacial freshwater release on regional sea-ice cover in the Southern Ocean

    Science.gov (United States)

    Merino, Nacho; Jourdain, Nicolas C.; Le Sommer, Julien; Goosse, Hugues; Mathiot, Pierre; Durand, Gael

    2018-01-01

    The sensitivity of Antarctic sea-ice to increasing glacial freshwater release into the Southern Ocean is studied in a series of 31-year ocean/sea-ice/iceberg model simulations. Glaciological estimates of ice-shelf melting and iceberg calving are used to better constrain the spatial distribution and magnitude of freshwater forcing around Antarctica. Two scenarios of glacial freshwater forcing have been designed to account for a decadal perturbation in glacial freshwater release to the Southern Ocean. For the first time, this perturbation explicitly takes into consideration the spatial distribution of changes in the volume of Antarctic ice shelves, which is found to be a key component of changes in freshwater release. In addition, glacial freshwater-induced changes in sea ice are compared to typical changes induced by the decadal evolution of atmospheric states. Our results show that, in general, the increase in glacial freshwater release increases Antarctic sea ice extent. But the response is opposite in some regions like the coastal Amundsen Sea, implying that distinct physical mechanisms are involved in the response. We also show that changes in freshwater forcing may induce large changes in sea-ice thickness, explaining about one half of the total change due to the combination of atmospheric and freshwater changes. The regional contrasts in our results suggest a need for improving the representation of freshwater sources and their evolution in climate models.

  16. ESTIMATIVA DO VOLUME TOTAL DE MADEIRA EM ESPÉCIES DE EUCALIPTO A PARTIR DE IMAGENS DE SATÉLITE LANDSAT

    Directory of Open Access Journals (Sweden)

    Elias Fernando Berra

    2012-01-01

    Full Text Available Models relating spectral answers with biophysical parameters aim estimate variables, such as wood volume, without the necessity of frequent field measurements. The objective was to develop models to estimatewood volume by Landsat 5 TM images, supported by regional forest inventory data. The image was georeferenced and converted to spectral reflectance. After, the images-index NDVI (Normalized Difference Vegetation Index and SR (Simple Ratio was generated. The reflectance values of both spectral bands (TM1, TM2, TM3 e TM4 and indices (NDVI and SR was related with the wood volume. The biggest correlation with volume was with the NDVI and SR indices. The variables selection was made by Stepwise method, which returned three regression models as significant to explain the variation in volume. Finally,the best fitted model was selected (volume = -830,95 + 46,05 × (SR + 107,47 × (TM2, which was applied on the Landsat image where the pixels had started to represent the estimated volume in m³/ha on the Eucalyptus sp. production units. This model, significant at 95 % confidence level, explains 68 % of the wood volume variation.

  17. Icing Impacts on Wind Energy Production

    DEFF Research Database (Denmark)

    Davis, Neil

    was developed for the identification of icing periods from the turbine power data and the nacelle wind speeds. This method was based on the spread of power production observations at cold temperatures that was not seen during warmer periods. Using the insights gained through the observational analysis...... and the turbine power loss. The model took the shape of a hierarchal model that combined a decision tree model, based on the existence of ice on the turbine blade, and two Generalized Additive Models (GAM). The GAM for periods where icing was forecast was found to include the terms wind speed, total ice mass...

  18. Modelling large-scale ice-sheet-climate interactions at the last glacial inception

    Science.gov (United States)

    Browne, O. J. H.; Gregory, J. M.; Payne, A. J.; Ridley, J. K.; Rutt, I. C.

    2010-05-01

    In order to investigate the interactions between coevolving climate and ice-sheets on multimillenial timescales, a low-resolution atmosphere-ocean general circulation model (AOGCM) has been coupled to a three-dimensional thermomechanical ice-sheet model. We use the FAMOUS AOGCM, which is almost identical in formulation to the widely used HadCM3 AOGCM, but on account of its lower resolution (7.5° longitude × 5° latitude in the atmosphere, 3.75°× 2.5° in the ocean) it runs about ten times faster. We use the community ice-sheet model Glimmer at 20 km resolution, with the shallow ice approximation and an annual degree-day scheme for surface mass balance. With the FAMOUS-Glimmer coupled model, we have simulated the growth of the Laurentide and Fennoscandian ice sheets at the last glacial inception, under constant orbital forcing and atmospheric composition for 116 ka BP. Ice grows in both regions, totalling 5.8 m of sea-level equivalent in 10 ka, slower than proxy records suggest. Positive climate feedbacks reinforce this growth at local scales (order hundreds of kilometres), where changes are an order of magnitude larger than on the global average. The albedo feedback (higher local albedo means a cooler climate) is important in the initial expansion of the ice-sheet area. The topography feedback (higher surface means a cooler climate) affects ice-sheet thickness and is not noticeable for the first 1 ka. These two feedbacks reinforce each other. Without them, the ice volume is ~90% less after 10 ka. In Laurentia, ice expands initially on the Canadian Arctic islands. The glaciation of the islands eventually cools the nearby mainland climate sufficiently to produce a positive mass balance there. Adjacent to the ice-sheets, cloud feedbacks tend to reduce the surface mass balance and restrain ice growth; this is an example of a local feedback whose simulation requires a model that includes detailed atmospheric physics.

  19. State of Arctic Sea Ice North of Svalbard during N-ICE2015

    Science.gov (United States)

    Rösel, Anja; King, Jennifer; Gerland, Sebastian

    2016-04-01

    The N-ICE2015 cruise, led by the Norwegian Polar Institute, was a drift experiment with the research vessel R/V Lance from January to June 2015, where the ship started the drift North of Svalbard at 83°14.45' N, 21°31.41' E. The drift was repeated as soon as the vessel drifted free. Altogether, 4 ice stations where installed and the complex ocean-sea ice-atmosphere system was studied with an interdisciplinary Approach. During the N-ICE2015 cruise, extensive ice thickness and snow depth measurements were performed during both, winter and summer conditions. Total ice and snow thickness was measured with ground-based and airborne electromagnetic instruments; snow depth was measured with a GPS snow depth probe. Additionally, ice mass balance and snow buoys were deployed. Snow and ice thickness measurements were performed on repeated transects to quantify the ice growth or loss as well as the snow accumulation and melt rate. Additionally, we collected independent values on surveys to determine the general ice thickness distribution. Average snow depths of 32 cm on first year ice, and 52 cm on multi-year ice were measured in January, the mean snow depth on all ice types even increased until end of March to 49 cm. The average total ice and snow thickness in winter conditions was 1.92 m. During winter we found a small growth rate on multi-year ice of about 15 cm in 2 months, due to above-average snow depths and some extraordinary storm events that came along with mild temperatures. In contrast thereto, we also were able to study new ice formation and thin ice on newly formed leads. In summer conditions an enormous melt rate, mainly driven by a warm Atlantic water inflow in the marginal ice zone, was observed during two ice stations with melt rates of up to 20 cm per 24 hours. To reinforce the local measurements around the ship and to confirm their significance on a larger scale, we compare them to airborne thickness measurements and classified SAR-satellite scenes. The

  20. Multiphase Reactive Transport and Platelet Ice Accretion in the Sea Ice of McMurdo Sound, Antarctica

    Science.gov (United States)

    Buffo, J. J.; Schmidt, B. E.; Huber, C.

    2018-01-01

    Sea ice seasonally to interannually forms a thermal, chemical, and physical boundary between the atmosphere and hydrosphere over tens of millions of square kilometers of ocean. Its presence affects both local and global climate and ocean dynamics, ice shelf processes, and biological communities. Accurate incorporation of sea ice growth and decay, and its associated thermal and physiochemical processes, is underrepresented in large-scale models due to the complex physics that dictate oceanic ice formation and evolution. Two phenomena complicate sea ice simulation, particularly in the Antarctic: the multiphase physics of reactive transport brought about by the inhomogeneous solidification of seawater, and the buoyancy driven accretion of platelet ice formed by supercooled ice shelf water onto the basal surface of the overlying ice. Here a one-dimensional finite difference model capable of simulating both processes is developed and tested against ice core data. Temperature, salinity, liquid fraction, fluid velocity, total salt content, and ice structure are computed during model runs. The model results agree well with empirical observations and simulations highlight the effect platelet ice accretion has on overall ice thickness and characteristics. Results from sensitivity studies emphasize the need to further constrain sea ice microstructure and the associated physics, particularly permeability-porosity relationships, if a complete model of sea ice evolution is to be obtained. Additionally, implications for terrestrial ice shelves and icy moons in the solar system are discussed.

  1. Using Remote Sensing Data to Parameterize Ice Jam Modeling for a Northern Inland Delta

    Directory of Open Access Journals (Sweden)

    Fan Zhang

    2017-04-01

    Full Text Available The Slave River is a northern river in Canada, with ice being an important component of its flow regime for at least half of the year. During the spring breakup period, ice jams and ice-jam flooding can occur in the Slave River Delta, which is of benefit for the replenishment of moisture and sediment required to maintain the ecological integrity of the delta. To better understand the ice jam processes that lead to flooding, as well as the replenishment of the delta, the one-dimensional hydraulic river ice model RIVICE was implemented to simulate and explore ice jam formation in the Slave River Delta. Incoming ice volume, a crucial input parameter for RIVICE, was determined by the novel approach of using MODIS space-born remote sensing imagery. Space-borne and air-borne remote sensing data were used to parameterize the upstream ice volume available for ice jamming. Gauged data was used to complement modeling calibration and validation. HEC-RAS, another one-dimensional hydrodynamic model, was used to determine ice volumes required for equilibrium jams and the upper limit of ice volume that a jam can sustain, as well as being used as a threshold for the volumes estimated by the dynamic ice jam simulations using RIVICE. Parameter sensitivity analysis shows that morphological and hydraulic properties have great impacts on the ice jam length and water depth in the Slave River Delta.

  2. Automatic total kidney volume measurement on follow-up magnetic resonance images to facilitate monitoring of autosomal dominant polycystic kidney disease progression.

    Science.gov (United States)

    Kline, Timothy L; Korfiatis, Panagiotis; Edwards, Marie E; Warner, Joshua D; Irazabal, Maria V; King, Bernard F; Torres, Vicente E; Erickson, Bradley J

    2016-02-01

    Renal imaging examinations provide high-resolution information about the anatomic structure of the kidneys and are used to measure total kidney volume (TKV) in autosomal dominant polycystic kidney disease (ADPKD) patients. TKV has become the gold-standard image biomarker for ADPKD progression at early stages of the disease and is used in clinical trials to characterize treatment efficacy. Automated methods to segment the kidneys and measure TKV are desirable because of the long time requirement for manual approaches such as stereology or planimetry tracings. However, ADPKD kidney segmentation is complicated by a number of factors, including irregular kidney shapes and variable tissue signal at the kidney borders. We describe an image processing approach that overcomes these problems by using a baseline segmentation initialization to provide automatic segmentation of follow-up scans obtained years apart. We validated our approach using 20 patients with complete baseline and follow-up T1-weighted magnetic resonance images. Both manual tracing and stereology were used to calculate TKV, with two observers performing manual tracings and one observer performing repeat tracings. Linear correlation and Bland-Altman analysis were performed to compare the different approaches. Our automated approach measured TKV at a level of accuracy (mean difference ± standard error = 0.99 ± 0.79%) on par with both intraobserver (0.77 ± 0.46%) and interobserver variability (1.34 ± 0.70%) of manual tracings. All approaches had excellent agreement and compared favorably with ground-truth manual tracing with interobserver, stereological and automated approaches having 95% confidence intervals ∼ ± 100 mL. Our method enables fast, cost-effective and reproducible quantification of ADPKD progression that will facilitate and lower the costs of clinical trials in ADPKD and other disorders requiring accurate, longitudinal kidney quantification. In addition, it will hasten the routine use of

  3. Baseline Metabolic Tumor Volume and Total Lesion Glycolysis Are Associated With Survival Outcomes in Patients With Locally Advanced Pancreatic Cancer Receiving Stereotactic Body Radiation Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Dholakia, Avani S. [Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland (United States); Chaudhry, Muhammad; Leal, Jeffrey P. [Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, Maryland (United States); Chang, Daniel T. [Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California (United States); Raman, Siva P. [Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, Maryland (United States); Hacker-Prietz, Amy [Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland (United States); Su, Zheng; Pai, Jonathan [Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California (United States); Oteiza, Katharine E.; Griffith, Mary E. [Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland (United States); Wahl, Richard L. [Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, Maryland (United States); Tryggestad, Erik [Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland (United States); Pawlik, Timothy [Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland (United States); Laheru, Daniel A. [Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, Maryland (United States); Wolfgang, Christopher L. [Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland (United States); Koong, Albert C. [Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California (United States); and others

    2014-07-01

    Purpose: Although previous studies have demonstrated the prognostic value of positron emission tomography (PET) parameters in other malignancies, the role of PET in pancreatic cancer has yet to be well established. We analyzed the prognostic utility of PET for patients with locally advanced pancreatic cancer (LAPC) undergoing fractionated stereotactic body radiation therapy (SBRT). Materials and Methods: Thirty-two patients with LAPC in a prospective clinical trial received up to 3 doses of gemcitabine, followed by 33 Gy in 5 fractions of 6.6 Gy, using SBRT. All patients received a baseline PET scan prior to SBRT (pre-SBRT PET). Metabolic tumor volume (MTV), total lesion glycolysis (TLG), and maximum and peak standardized uptake values (SUV{sub max} and SUV{sub peak}) on pre-SBRT PET scans were calculated using custom-designed software. Disease was measured at a threshold based on the liver SUV, using the equation Liver{sub mean} + [2 × Liver{sub sd}]. Median values of PET parameters were used as cutoffs when assessing their prognostic potential through Cox regression analyses. Results: Of the 32 patients, the majority were male (n=19, 59%), 65 years or older (n=21, 66%), and had tumors located in the pancreatic head (n=27, 84%). Twenty-seven patients (84%) received induction gemcitabine prior to SBRT. Median overall survival for the entire cohort was 18.8 months (95% confidence interval [CI], 15.7-22.0). An MTV of 26.8 cm{sup 3} or greater (hazard ratio [HR] 4.46, 95% CI 1.64-5.88, P<.003) and TLG of 70.9 or greater (HR 3.08, 95% CI 1.18-8.02, P<.021) on pre-SBRT PET scan were associated with inferior overall survival on univariate analysis. Both pre-SBRT MTV (HR 5.13, 95% CI 1.19-22.21, P=.029) and TLG (HR 3.34, 95% CI 1.07-10.48, P=.038) remained independently associated with overall survival in separate multivariate analyses. Conclusions: Pre-SBRT MTV and TLG are potential predictive factors for overall survival in patients with LAPC and may assist in

  4. Baseline Metabolic Tumor Volume and Total Lesion Glycolysis Are Associated With Survival Outcomes in Patients With Locally Advanced Pancreatic Cancer Receiving Stereotactic Body Radiation Therapy

    International Nuclear Information System (INIS)

    Dholakia, Avani S.; Chaudhry, Muhammad; Leal, Jeffrey P.; Chang, Daniel T.; Raman, Siva P.; Hacker-Prietz, Amy; Su, Zheng; Pai, Jonathan; Oteiza, Katharine E.; Griffith, Mary E.; Wahl, Richard L.; Tryggestad, Erik; Pawlik, Timothy; Laheru, Daniel A.; Wolfgang, Christopher L.; Koong, Albert C.

    2014-01-01

    Purpose: Although previous studies have demonstrated the prognostic value of positron emission tomography (PET) parameters in other malignancies, the role of PET in pancreatic cancer has yet to be well established. We analyzed the prognostic utility of PET for patients with locally advanced pancreatic cancer (LAPC) undergoing fractionated stereotactic body radiation therapy (SBRT). Materials and Methods: Thirty-two patients with LAPC in a prospective clinical trial received up to 3 doses of gemcitabine, followed by 33 Gy in 5 fractions of 6.6 Gy, using SBRT. All patients received a baseline PET scan prior to SBRT (pre-SBRT PET). Metabolic tumor volume (MTV), total lesion glycolysis (TLG), and maximum and peak standardized uptake values (SUV max and SUV peak ) on pre-SBRT PET scans were calculated using custom-designed software. Disease was measured at a threshold based on the liver SUV, using the equation Liver mean + [2 × Liver sd ]. Median values of PET parameters were used as cutoffs when assessing their prognostic potential through Cox regression analyses. Results: Of the 32 patients, the majority were male (n=19, 59%), 65 years or older (n=21, 66%), and had tumors located in the pancreatic head (n=27, 84%). Twenty-seven patients (84%) received induction gemcitabine prior to SBRT. Median overall survival for the entire cohort was 18.8 months (95% confidence interval [CI], 15.7-22.0). An MTV of 26.8 cm 3 or greater (hazard ratio [HR] 4.46, 95% CI 1.64-5.88, P<.003) and TLG of 70.9 or greater (HR 3.08, 95% CI 1.18-8.02, P<.021) on pre-SBRT PET scan were associated with inferior overall survival on univariate analysis. Both pre-SBRT MTV (HR 5.13, 95% CI 1.19-22.21, P=.029) and TLG (HR 3.34, 95% CI 1.07-10.48, P=.038) remained independently associated with overall survival in separate multivariate analyses. Conclusions: Pre-SBRT MTV and TLG are potential predictive factors for overall survival in patients with LAPC and may assist in tailoring therapy

  5. The total right/left-volume index: a new and simplified cardiac magnetic resonance measure to evaluate the severity of Ebstein anomaly of the tricuspid valve: a comparison with heart failure markers from various modalities.

    Science.gov (United States)

    Hösch, Olga; Sohns, Jan Martin; Nguyen, Thuy-Trang; Lauerer, Peter; Rosenberg, Christina; Kowallick, Johannes Tammo; Kutty, Shelby; Unterberg, Christina; Schuster, Andreas; Faßhauer, Martin; Staab, Wieland; Paul, Thomas; Lotz, Joachim; Steinmetz, Michael

    2014-07-01

    The classification of clinical severity of Ebstein anomaly still remains a challenge. The aim of this study was to focus on the interaction of the pathologically altered right heart with the anatomically-supposedly-normal left heart and to derive from cardiac magnetic resonance (CMR) a simple imaging measure for the clinical severity of Ebstein anomaly. Twenty-five patients at a mean age of 26±14 years with unrepaired Ebstein anomaly were examined in a prospective study. Disease severity was classified using CMR volumes and functional measurements in comparison with heart failure markers from clinical data, ECG, laboratory and cardiopulmonary exercise testing, and echocardiography. All examinations were completed within 24 hours. A total right/left-volume index was defined from end-diastolic volume measurements in CMR: total right/left-volume index=(RA+aRV+fRV)/(LA+LV). Mean total right/left-volume index was 2.6±1.7 (normal values: 1.1±0.1). This new total right/left-volume index correlated with almost all clinically used biomarkers of heart failure: brain natriuretic peptide (r=0.691; P=0.0003), QRS (r=0.432; P=0.039), peak oxygen consumption/kg (r=-0.479; P=0.024), ventilatory response to carbon dioxide production at anaerobic threshold (r=0.426; P=0.048), the severity of tricuspid regurgitation (r=0.692; P=0.009), tricuspid valve offset (r=0.583; P=0.004), and tricuspid annular plane systolic excursion (r=0.554; P=0.006). Previously described severity indices ([RA+aRV]/[fRV+LA+LV]) and fRV/LV end-diastolic volume corresponded only to some parameters. In patients with Ebstein anomaly, the easily acquired index of right-sided to left-sided heart volumes from CMR correlated well with established heart failure markers. Our data suggest that the total right/left-volume index should be used as a new and simplified CMR measure, allowing more accurate assessment of disease severity than previously described scoring systems. © 2014 American Heart Association, Inc.

  6. Dead-ice environments

    DEFF Research Database (Denmark)

    Krüger, Johannes; Kjær, Kurt H.; Schomacker, Anders

    2010-01-01

    glacier environment. The scientific challenges are to answer the key questions. What are the conditions for dead-ice formation? From which sources does the sediment cover originate? Which melting and reworking processes act in the ice-cored moraines? What is the rate of de-icing in the ice-cored moraines...

  7. Rate of ice accumulation during ice storms

    Energy Technology Data Exchange (ETDEWEB)

    Feknous, N. [SNC-Lavalin, Montreal, PQ (Canada); Chouinard, L. [McGill Univ., Montreal, PQ (Canada); Sabourin, G. [Hydro-Quebec, Montreal, PQ (Canada)

    2005-07-01

    The rate of glaze ice accumulation is the result of a complex process dependent on numerous meteorological and physical factors. The aim of this paper was to estimate the distribution rate of glaze ice accumulation on conductors in southern Quebec for use in the design of mechanical and electrical de-icing devices. The analysis was based on direct observations of ice accumulation collected on passive ice meters. The historical database of Hydro-Quebec, which contains observations at over 140 stations over period of 25 years, was used to compute accumulation rates. Data was processed so that each glaze ice event was numbered in a chronological sequence. Each event consisted of the time series of ice accumulations on each of the 8 cylinders of the ice meters, as well as on 5 of its surfaces. Observed rates were converted to represent the average ice on a 30 mm diameter conductor at 30 m above ground with a span of 300 m. Observations were corrected to account for the water content of the glaze ice as evidenced by the presence of icicles. Results indicated that despite significant spatial variations in the expected severity of ice storms as a function of location, the distribution function for rates of accumulation were fairly similar and could be assumed to be independent of location. It was concluded that the observations from several sites could be combined in order to obtain better estimates of the distribution of hourly rates of ice accumulation. However, the rates were highly variable. For de-icing strategies, it was suggested that average accumulation rates over 12 hour periods were preferable, and that analyses should be performed for other time intervals to account for the variability in ice accumulation rates over time. In addition, accumulation rates did not appear to be highly correlated with average wind speed for maximum hourly accumulation rates. 3 refs., 2 tabs., 10 figs.

  8. Chronic Use of Aspirin and Total White Matter Lesion Volume: Results from the Women's Health Initiative Memory Study of Magnetic Resonance Imaging Study.

    Science.gov (United States)

    Holcombe, Andrea; Ammann, Eric; Espeland, Mark A; Kelley, Brendan J; Manson, JoAnn E; Wallace, Robert; Robinson, Jennifer

    2017-10-01

    To investigate the relationship between aspirin and subclinical cerebrovascular heath, we evaluated the effect of chronic aspirin use on white matter lesions (WML) volume among women. Chronic aspirin use was assessed in 1365 women who participated in the Women's Health Initiative Memory Study of Magnetic Resonance Imaging. Differences in WML volumes between aspirin users and nonusers were assessed with linear mixed models. A number of secondary analyses were performed, including lobe-specific analyses, subgroup analyses based on participants' overall risk of cerebrovascular disease, and a dose-response relationship analysis. The mean age of the women at magnetic resonance imaging examination was 77.6 years. Sixty-one percent of participants were chronic aspirin users. After adjusting for demographic variables and comorbidities, chronic aspirin use was nonsignificantly associated with 4.8% (95% CI: -6.8%, 17.9%) larger WML volumes. These null findings were confirmed in secondary and sensitivity analyses, including an active comparator evaluation where aspirin users were compared to users of nonaspirin nonsteroidal anti-inflammatory drugs or acetaminophen. There was a nonsignificant difference in WML volumes between aspirin users and nonusers. Further, our results suggest that chronic aspirin use may not have a clinically significant effect on WML volumes in women. Published by Elsevier Inc.

  9. Spatial and temporal multiyear sea ice distributions in the Arctic: A neural network analysis of SSM/I data, 1988-2001

    Science.gov (United States)

    Belchansky, G.I.; Douglas, D.C.; Alpatsky, I.V.; Platonov, Nikita G.

    2004-01-01

    the previous 8-year decline in total area, but it was followed by an accelerated and compensatory decline during the subsequent 4 years. Seventy-five percent of the interannual variation in January multiyear sea ice area was explained by linear regression on two atmospheric parameters: the previous inter's (JFM) Arctic Oscillation index as a proxy to melt duration and the previous year's average sea level pressure gradient across the Fram Strait as a proxy to annual ice export. Consecutive year changes (1994-2001) in January multiyear ice volume were significantly correlated with duration of the intervening melt season (R2 = 0.73, -80.0 km3/d-1), emphasizing a large thermodynamic influence on the Arctic's mass sea ice balance during summers with anomalous melt durations.

  10. Integration of airborne altimetry and in situ radar measurements to estimate marine ice thickness beneath the Larsen C ice shelf, Antarctic Peninsula

    Science.gov (United States)

    McGrath, D.; Steffen, K.; Rodriguez Lagos, J.

    2010-12-01

    Observed atmospheric and oceanic warming is driving significant retreat and / or collapse of ice shelves along the Antarctic Peninsula totaling over 25,000 km2 in the past five decades. Basal melting of meteoric ice can occur near the grounding line of deep glacier inflows if the ocean water is above the pressure melting point. Buoyant meltwater will develop thermohaline circulation, rising beneath the ice shelf, where it may become supercooled and subsequently refreeze in ice draft minima. Marine ice, due to its warm and thus relatively viscous nature, is hypothesized to suture parallel flow bands, increasing ice shelf stability by arresting fracture propagation and controlling iceberg calving dimensions. Thus efforts to model ice shelf stability require accurate estimates of marine ice location and thickness. Ice thickness of a floating ice shelf can be determined in two manners: (1) from measurements of ice elevation above sea level and the calculation of ice thickness from assumptions of hydrostatic equilibrium, and (2) from radar echo measurements of the ice-water interface. Marine ice can confound the latter because its high dielectric constant and strong absorptive properties attenuate the radar energy, often preventing a return signal from the bottom of the ice shelf. These two methods are complementary for determining the marine ice component though because positive anomalies in (1) relative to (2) suggest regions of marine ice accretion. Nearly 350 km of ice penetrating radar (25 MHz) surveys were collected on the Larsen C ice shelf, in conjunction with kinematic GPS measurements and collocated with surface elevation data from the NASA Airborne Topographic Mapper (ATM) as part of the ICE Bridge mission in 2009. Basal ice topography and total ice thickness is accurately mapped along the survey lines and compared with calculated ice thickness from both the kinematic GPS and ATM elevation data. Positive anomalies are discussed in light of visible imagery and

  11. High density amorphous ice and its phase transition to ice XII

    International Nuclear Information System (INIS)

    Kohl, I.

    2001-07-01

    1998 Lobban et al. reported the neutron diffraction data of a new phase of ice, called ice XII, which formed at 260 K on compression of water within the domain of ice V at a pressure of 0.5 GPa. Surprisingly ice XII forms as an incidental product in the preparation of high-density amorphous ice (HDA) on compression of hexagonale ice (ice Ih) at 77 K up to pressures = 1.3 GPa. A decisive experimental detail is the use of an indium container: when compressing ice Ih in a pressure vessel with indium linings, then reproducibly HDA (high density amorphous ice) forms, but without indium randomly scattered relative amounts of ice XII and HDA form. Ice XII forms on compression of ice Ih at 77 K only via HDA, and not directly from ice Ih. Its formation requires a sudden pronounced apparent pressure drop of ca 0.18 GPa at pressures ca 1.1 GPa. These apparent pressure drops can be caused by buildup friction between the piston and the pressure vessel and its sudden release on further compression. I propose that shock-waves generated by apparent pressure drops cause transient local heating and that this induces nucleation and crystal growth. A specific reproducible method to prepare ice XII is heating HDA in a pressure vessel with indium linings at constant pressures (or constant volume). The ice XII (meta-)stability domain extends between ca 158 and 212 K from ca 0.7 to ca 1.5 GPa. DSC (differential scanning calorimetry) and x-ray powder diffraction revealed, that on heating at atmospheric pressure ice XII transforms directly into cubic ice (ice Ic) at 154 K (heating rate 10 K min - 1) and not into an amorphous form before transition to ice Ic. The enthalpy of the ice XII - ice Ic transition is -1.21 ± 0.07 kJ mol -1 . An estimation of the Gibbs free energy at atmospheric pressure and about 140 K results that ice XII is thermodynamically more stable than ice VI. In the heating curve of ice XII a reversible endothermic step can be found at the onset temperature (heating rate

  12. Contrasts in Sea Ice Formation and Production in the Arctic Seasonal and Perennial Ice Zones

    Science.gov (United States)

    Kwok, R.

    2006-01-01

    Four years (1997-2000) of RADARSAT Geophysical Processor System (RGPS) data are used to contrast the sea ice deformation and production regionally, and in the seasonal (SIZ) and perennial (PIZ) ice zones. Ice production is of seasonal ice in openings during the winter. 3-day estimates of these quantities are provided within Lagrangian elements initially 10 km on a side. A distinct seasonal cycle is seen in both zones with these estimates highest in the late fall and with seasonal minimums in the mid-winter. Regional divergence over the winter could be up to 30%. Spatially, the highest deformation is in the SIZ north of coastal Alaska. Both ice deformation and production are higher in the SIZ: deformation-related ice production in the SIZ (approx.0.5 m) is 1.5-2.3 times that of the PIZ (approx.0.3 m) - this is connected to ice strength and thickness. Atmospheric forcing and boundary layer structure contribute to only the seasonal and interannual variability. Seasonal ice growth in ice fractures accounts for approx.25-40% of the total ice production of the Arctic Ocean. By itself, this deformation-ice production relationship could be considered a negative feedback when thickness is perturbed. However, the overall effect on ice production in the face of increasing seasonal and thinner/weaker ice coverage could be modified by: local destabilization of the water column promoting overturning of warmer water due to increased brine rejection; and, the upwelling of the pynocline associated with increased occurrence of large shear motion in sea ice.

  13. Total and regional brain volumes in a population-based normative sample from 4 to 18 years: the NIH MRI Study of Normal Brain Development.

    Science.gov (United States)

    2012-01-01

    Using a population-based sampling strategy, the National Institutes of Health (NIH) Magnetic Resonance Imaging Study of Normal Brain Development compiled a longitudinal normative reference database of neuroimaging and correlated clinical/behavioral data from a demographically representative sample of healthy children and adolescents aged newborn through early adulthood. The present paper reports brain volume data for 325 children, ages 4.5-18 years, from the first cross-sectional time point. Measures included volumes of whole-brain gray matter (GM) and white matter (WM), left and right lateral ventricles, frontal, temporal, parietal and occipital lobe GM and WM, subcortical GM (thalamus, caudate, putamen, and globus pallidus), cerebellum, and brainstem. Associations with cross-sectional age, sex, family income, parental education, and body mass index (BMI) were evaluated. Key observations are: 1) age-related decreases in lobar GM most prominent in parietal and occipital cortex; 2) age-related increases in lobar WM, greatest in occipital, followed by the temporal lobe; 3) age-related trajectories predominantly curvilinear in females, but linear in males; and 4) small systematic associations of brain tissue volumes with BMI but not with IQ, family income, or parental education. These findings constitute a normative reference on regional brain volumes in children and adolescents.

  14. Spatial patterning and persistence of meltwater on ice shelves and the implications for ice shelf collapse

    Science.gov (United States)

    Robel, A.; MacAyeal, D. R.; Tsai, V. C.; Shean, D. E.

    2017-12-01

    Observations indicate that for at least the last few decades, there has been extensive surface melting over ice shelves in Antarctica. Meltwater either collects in ponds or flows over the surface in streams that discharge to the ocean. The spatial organization and persistence of this meltwater can have a significant influence on the thermomechanical ice shelf state through albedo, turbulent heat exchange, refreezing and hydrofracture. However, as more meltwater forms on Antarctic ice shelves, there is no general theory that predicts the spatial pattern of meltwater ponded on the ice shelf surface and the volume of meltwater runoff to the ocean. Here, we show how dynamical systems tools, such as cellular automata, can be used to calculate the expected distribution of meltwater on ice shelf surfaces. These tools can also be used to explore how ice shelf surface morphology is modified by meltwater albedo and turbulent heating feedbacks. We apply these numerical approaches to new high-resolution digital elevation models for ice shelves in West Antarctica. Additionally, we survey the prospects of developing general rules of meltwater patterning by applying scaling approaches from percolation theory. We conclude by discussing the types of ice shelves that are more likely to cause ice shelf collapse through surface melt-induced hydrofracture or thermomechanical weakening.

  15. Distributions of crystals and gas bubbles in reservoir ice during growth period

    Directory of Open Access Journals (Sweden)

    Zhi-jun Li

    2011-06-01

    Full Text Available In order to understand the dominant factors of the physical properties of ice in ice thermodynamics and mechanics, in-situ observations of ice growth and decay processes were carried out. Two samplings were conducted in the fast and steady ice growth stages. Ice pieces were used to observe ice crystals and gas bubbles in ice, and to measure the ice density. Vertical profiles of the type and size of ice crystals, shape and size of gas bubbles, and gas bubble content, as well as the ice density, were obtained. The results show that the upper layer of the ice pieces is granular ice and the lower layer is columnar ice; the average crystal size increases with the ice depth and remains steady in the fast and steady ice growth stages; the shape of gas bubbles in the upper layer of ice pieces is spherical with higher total content, and the shape in the middle and lower layers is cylinder with lower total content; the gas bubble size and content vary with the ice growth stage; and the ice density decreases with the increase of the gas bubble content.

  16. Simultaneous retrieval of sea ice thickness and snow depth using concurrent active altimetry and passive L-band remote sensing data

    Science.gov (United States)

    Zhou, L.; Xu, S.; Liu, J.

    2017-12-01

    The retrieval of sea ice thickness mainly relies on satellite altimetry, and the freeboard measurements are converted to sea ice thickness (hi) under certain assumptions over snow loading. The uncertain in snow depth (hs) is a major source of uncertainty in the retrieved sea ice thickness and total volume for both radar and laser altimetry. In this study, novel algorithms for the simultaneous retrieval of hi and hs are proposed for the data synergy of L-band (1.4 GHz) passive remote sensing and both types of active altimetry: (1) L-band (1.4GHz) brightness temperature (TB) from Soil Moisture Ocean Salinity (SMOS) satellite and sea ice freeboard (FBice) from radar altimetry, (2) L-band TB data and snow freeboard (FBsnow) from laser altimetry. Two physical models serve as the forward models for the retrieval: L-band radiation model, and the hydrostatic equilibrium model. Verification with SMOS and Operational IceBridge (OIB) data is carried out, showing overall good retrieval accuracy for both sea ice parameters. Specifically, we show that the covariability between hs and FBsnow is crucial for the synergy between TB and FBsnow. Comparison with existing algorithms shows lower uncertainty in both sea ice parameters, and that the uncertainty in the retrieved sea ice thickness as caused by that of snow depth is spatially uncorrelated, with the potential reduction of the volume uncertainty through spatial sampling. The proposed algorithms can be applied to the retrieval of sea ice parameters at basin-scale, using concurrent active and passive remote sensing data based on satellites.

  17. Stochastic ice stream dynamics.

    Science.gov (United States)

    Mantelli, Elisa; Bertagni, Matteo Bernard; Ridolfi, Luca

    2016-08-09

    Ice streams are narrow corridors of fast-flowing ice that constitute the arterial drainage network of ice sheets. Therefore, changes in ice stream flow are key to understanding paleoclimate, sea level changes, and rapid disintegration of ice sheets during deglaciation. The dynamics of ice flow are tightly coupled to the climate system through atmospheric temperature and snow recharge, which are known exhibit stochastic variability. Here we focus on the interplay between stochastic climate forcing and ice stream temporal dynamics. Our work demonstrates that realistic climate fluctuations are able to (i) induce the coexistence of dynamic behaviors that would be incompatible in a purely deterministic system and (ii) drive ice stream flow away from the regime expected in a steady climate. We conclude that environmental noise appears to be crucial to interpreting the past behavior of ice sheets, as well as to predicting their future evolution.

  18. Ice-skating injuries.

    Science.gov (United States)

    Williamson, D M; Lowdon, I M

    1986-05-01

    The range of injuries sustained at an ice-rink and presented to an Accident Service department is described. A total of 203 patients with 222 injuries presented themselves during a 2-month period. There were 103 noteworthy injuries, including 61 fractures, 2 dislocations and 2 severed tendons, but the commonest injuries were wounds, sprains and bruises. Beginners appear to be more prone to injury than experienced skaters. In addition to using well-fitting skate-boots to protect the ankle, some injuries could be avoided by wearing elbow and knee pads, and a thick pair of gloves. The number of injuries compared with the total number of skaters was small but produced a noteworthy increase in the workload of the Accident Service.

  19. Regional Changes in the Sea Ice Cover and Ice Production in the Antarctic

    Science.gov (United States)

    Comiso, Josefino C.

    2011-01-01

    Coastal polynyas around the Antarctic continent have been regarded as sea ice factories because of high ice production rates in these regions. The observation of a positive trend in the extent of Antarctic sea ice during the satellite era has been intriguing in light of the observed rapid decline of the ice extent in the Arctic. The results of analysis of the time series of passive microwave data indicate large regional variability with the trends being strongly positive in the Ross Sea, strongly negative in the Bellingshausen/Amundsen Seas and close to zero in the other regions. The atmospheric circulation in the Antarctic is controlled mainly by the Southern Annular Mode (SAM) and the marginal ice zone around the continent shows an alternating pattern of advance and retreat suggesting the presence of a propagating wave (called Antarctic Circumpolar Wave) around the circumpolar region. The results of analysis of the passive microwave data suggest that the positive trend in the Antarctic sea ice cover could be caused primarily by enhanced ice production in the Ross Sea that may be associated with more persistent and larger coastal polynyas in the region. Over the Ross Sea shelf, analysis of sea ice drift data from 1992 to 2008 yields a positive rate-of-increase in the net ice export of about 30,000 km2 per year. For a characteristic ice thickness of 0.6 m, this yields a volume transport of about 20 km3/year, which is almost identical, within error bars, to our estimate of the trend in ice production. In addition to the possibility of changes in SAM, modeling studies have also indicated that the ozone hole may have a role in that it causes the deepening of the lows in the western Antarctic region thereby causing strong winds to occur offthe Ross-ice shelf.

  20. Medical ice slurry production device

    Science.gov (United States)

    Kasza, Kenneth E [Palos Park, IL; Oras, John [Des Plaines, IL; Son, HyunJin [Naperville, IL

    2008-06-24

    The present invention relates to an apparatus for producing sterile ice slurries for medical cooling applications. The apparatus is capable of producing highly loaded slurries suitable for delivery to targeted internal organs of a patient, such as the brain, heart, lungs, stomach, kidneys, pancreas, and others, through medical size diameter tubing. The ice slurry production apparatus includes a slurry production reservoir adapted to contain a volume of a saline solution. A flexible membrane crystallization surface is provided within the slurry production reservoir. The crystallization surface is chilled to a temperature below a freezing point of the saline solution within the reservoir such that ice particles form on the crystallization surface. A deflector in the form of a reciprocating member is provided for periodically distorting the crystallization surface and dislodging the ice particles which form on the crystallization surface. Using reservoir mixing the slurry is conditioned for easy pumping directly out of the production reservoir via medical tubing or delivery through other means such as squeeze bottles, squeeze bags, hypodermic syringes, manual hand delivery, and the like.

  1. Linescan camera evaluation of SSM/I 85.5 GHz sea ice retrieval

    DEFF Research Database (Denmark)

    Garrity, Caren; Lubin, Dan; Kern, Stefan

    2002-01-01

    misclassify clouds over open water as sea ice, and is therefore unreliable for locating the sea ice edge. The best algorithm for locating the sea ice edge is found to be the SEA LION algorithm, which explicitly uses meteorological reanalysis data to correct for atmospheric contamination. For total sea ice...

  2. Contribution of deformation to sea-ice mass balance: a case study from an N-ICE2015 storm

    DEFF Research Database (Denmark)

    Itkin, Polona; Spreen, Gunnar; Hvidegaard, Sine Munk

    2018-01-01

    The fastest and most efficient process of gaining sea ice volume is through the mechanical redistribution of mass as a consequence of deformation events. During the ice growth season divergent motion produces leads where new ice grows thermodynamically, while convergent motion fractures the ice...... and either piles the resultant ice blocks into ridges or rafts one floe under the other. Here we present an exceptionally detailed airborne dataset from a 9km2 area of first and second year ice in the Transpolar Drift north of Svalbard that allowed us to estimate the redistribution of mass from an observed...... deformation event. To achieve this level of detail we analyzed changes in sea ice freeboard acquired from two airborne laser scanner surveys just before and right after a deformation event brought on by a passing low pressure system. A linear regression model based on divergence during this storm can explain...

  3. Measurements of sea ice by satellite and airborne altimetry

    DEFF Research Database (Denmark)

    Kildegaard Rose, Stine

    the modal freeboard heights of 55 cm retrieved from the laser scanner data with the 25 cm retrieved from CryoSat-2 indicates a snow layer of 30 cm, due to the theory that a laser is reflected at the air/snow interface, while the radar is reflected at the snow/ice interface. In the other area, the modal...... freeboard is found to be 35 cm for both the airborne and satellite data implying, that the radar signal is here reflected from the snow surface, probably due to weather conditions. CryoSat-2 is very sensitive to returns from specular surfaces, even if they appear o_-nadir. This contaminates the “true...... and in fjord systems. The Greenland fjords exhange freshwater between the glaciers and the ocean. Measuring a snapshot of the ice mélange in front of Kangiata Nunˆta Sermia in southwest Greenland with airborne LiDAR, gives an estimate of the ice disharge since last autuum. The total volume of 1:70 _ 1:26 GT...

  4. Ice thickness profile surveying with ground penetrating radar at Artesonraju Glacier, Peru

    Science.gov (United States)

    Chisolm, Rachel; Rabatel, Antoine; McKinney, Daene; Condom, Thomas; Cochacin, Alejo; Davila Roller, Luzmilla

    2014-05-01

    Tropical glaciers are an essential component of the water resource systems in the mountainous regions where they are located, and a warming climate has resulted in the accelerated retreat of Andean glaciers in recent decades. The shrinkage of Andean glaciers influences the flood risk for communities living downstream as new glacial lakes have begun to form at the termini of some glaciers. As these lakes continue to grow in area and volume, they pose an increasing risk of glacial lake outburst floods (GLOFs). Ice thickness measurements have been a key missing link in studying the tropical glaciers in Peru and how climate change is likely to impact glacial melt and the growth of glacial lakes. Ground penetrating radar (GPR) has rarely been applied to glaciers in Peru to measure ice thickness, and these measurements can tell us a lot about how a warming climate will affect glaciers in terms of thickness changes. In the upper Paron Valley (Cordillera Blanca, Peru), an emerging lake has begun to form at the terminus of the Artesonraju Glacier, and this lake has key features, including overhanging ice and loose rock likely to create slides, that could trigger a catastrophic GLOF if the lake continues to grow. Because the glacier mass balance and lake mass balance are closely linked, ice thickness measurements and measurements of the bed slope of the Artesonraju Glacier and underlying bedrock can give us an idea of how the lake is likely to evolve in the coming decades. This study presents GPR data taken in July 2013 at the Artesonraju Glacier as part of a collaboration between the Unidad de Glaciologia y Recursos Hidricos (UGRH) of Peru, the Institut de Recherche pour le Développement (IRD) of France and the University of Texas at Austin (UT) of the United States of America. Two different GPR units belonging to UGRH and UT were used for subsurface imaging to create ice thickness profiles and to characterize the total volume of ice in the glacier. A common midpoint

  5. A natural ice boom

    Energy Technology Data Exchange (ETDEWEB)

    Hopper, H.R. [Manitoba Hydro, Winnipeg, MB (Canada)

    1998-10-01

    Planning for ice jams and ice movements are critical on the Nelson River in northern Manitoba in designing cofferdams. Experience on the St. Lawrence River demonstrated the possibility of exercising some control over ice action by judicious placement of log booms or ice control structures. The success of experiments with man-made controls led to field tests in which an ice sheet of sufficient magnitude and competence was introduced into the open water stream of the Nelson River. The ice sheet was subsequently jammed in a narrow channel, thereby creating a natural ice bridge or boom upstream of a proposed hydro development. Under favourable conditions, this boom would initiate the progression of the ice cover from its location upstream, cutting off the downstream reach from the ice producing potential of the upstream reach. Although ice would still be generated downstream, the length of the reach between the ice boom and the development site would be short enough that ice jamming at the development site would never occur. Although problems in blasting prevented the introduction of a competent ice sheet into the main stream of the river at the location chosen, sufficient confidence in the theory was gained to warrant further consideration. 4 refs., 1 tab., 10 figs.

  6. On the role of ice-nucleating aerosol in the formation of ice particles in tropical mesoscale convective systems

    Science.gov (United States)

    Ladino, Luis A.; Korolev, Alexei; Heckman, Ivan; Wolde, Mengistu; Fridlind, Ann M.; Ackerman, Andrew S.

    2018-01-01

    Over decades, the cloud physics community has debated the nature and role of aerosol particles in ice initiation. The present study shows that the measured concentration of ice crystals in tropical mesoscale convective systems exceeds the concentration of ice nucleating particles (INPs) by several orders of magnitude. The concentration of INPs was assessed from the measured aerosol particles concentration in the size range of 0.5 to 1 µm. The observations from this study suggest that primary ice crystals formed on INPs make only a minor contribution to the total concentration of ice crystals in tropical mesoscale convective systems. This is found by comparing the predicted INP number concentrations with in-situ ice particle number concentrations. The obtained measurements suggest that ice multiplication is the likely explanation for the observed high concentrations of ice crystals in this type of convective system. PMID:29551842

  7. Hydrogen-Bonding Surfaces for Ice Mitigation

    Science.gov (United States)

    Smith, Joseph G., Jr.; Wohl, Christopher J.; Kreeger, Richard E.; Hadley, Kevin R.; McDougall, Nicholas

    2014-01-01

    Ice formation on aircraft, either on the ground or in-flight, is a major safety issue. While ground icing events occur predominantly during the winter months, in-flight icing can happen anytime during the year. The latter is more problematic since it could result in increased drag and loss of lift. Under a Phase I ARMD NARI Seedling Activity, coated aluminum surfaces possessing hydrogen-bonding groups were under investigation for mitigating ice formation. Hydroxyl and methyl terminated dimethylethoxysilanes were prepared via known chemistries and characterized by spectroscopic methods. These materials were subsequently used to coat aluminum surfaces. Surface compositions were based on pure hydroxyl and methyl terminated species as well as mixtures of the two. Coated surfaces were characterized by contact angle goniometry. Receding water contact angle data suggested several potential surfaces that may exhibit reduced ice adhesion. Qualitative icing experiments performed under representative environmental temperatures using supercooled distilled water delivered via spray coating were inconclusive. Molecular modeling studies suggested that chain mobility affected the interface between ice and the surface more than terminal group chemical composition. Chain mobility resulted from the creation of "pockets" of increased free volume for longer chains to occupy.

  8. Processes driving sea ice variability in the Bering Sea in an eddying ocean/sea ice model: Mean seasonal cycle

    Science.gov (United States)

    Li, Linghan; McClean, Julie L.; Miller, Arthur J.; Eisenman, Ian; Hendershott, Myrl C.; Papadopoulos, Caroline A.

    2014-12-01

    The seasonal cycle of sea ice variability in the Bering Sea, together with the thermodynamic and dynamic processes that control it, are examined in a fine resolution (1/10°) global coupled ocean/sea-ice model configured in the Community Earth System Model (CESM) framework. The ocean/sea-ice model consists of the Los Alamos National Laboratory Parallel Ocean Program (POP) and the Los Alamos Sea Ice Model (CICE). The model was forced with time-varying reanalysis atmospheric forcing for the time period 1970-1989. This study focuses on the time period 1980-1989. The simulated seasonal-mean fields of sea ice concentration strongly resemble satellite-derived observations, as quantified by root-mean-square errors and pattern correlation coefficients. The sea ice energy budget reveals that the seasonal thermodynamic ice volume changes are dominated by the surface energy flux between the atmosphere and the ice in the northern region and by heat flux from the ocean to the ice along the southern ice edge, especially on the western side. The sea ice force balance analysis shows that sea ice motion is largely associated with wind stress. The force due to divergence of the internal ice stress tensor is large near the land boundaries in the north, and it is small in the central and southern ice-covered region. During winter, which dominates the annual mean, it is found that the simulated sea ice was mainly formed in the northern Bering Sea, with the maximum ice growth rate occurring along the coast due to cold air from northerly winds and ice motion away from the coast. South of St Lawrence Island, winds drive the model sea ice southwestward from the north to the southwestern part of the ice-covered region. Along the ice edge in the western Bering Sea, model sea ice is melted by warm ocean water, which is carried by the simulated Bering Slope Current flowing to the northwest, resulting in the S-shaped asymmetric ice edge. In spring and fall, similar thermodynamic and dynamic

  9. Forecast Icing Product

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Forecast Icing Product (FIP) is an automatically-generated index suitable for depicting areas of potentially hazardous airframe icing. The FIP algorithm uses...

  10. Current Icing Product

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Current Icing Product (CIP) is an automatically-generated index suitable for depicting areas of potentially hazardous airframe icing. The CIP algorithm combines...

  11. Defense Manpower Commission Staff Studies and Supporting Papers. Volume 2. The Total Force and Its Manpower Requirements Including Overviews of Each Service

    Science.gov (United States)

    1976-05-01

    J^^’.Si*!** \\ ir..’’T^-.’-T*TSfn titoa i iMBi’M, OTTŕ" ,^~" fraCk k^«^;-<^»J,..;^.a,L.^t»^^ri^fc ft WBMyLmH’.’JW*^Hi,.J , Jl,l|llliln|Kli|Pffl...also develop a means to inspect tube internals to insure they are clean 11. Develop a deep tank, high volume, high head hydraulic driven pump to...and procedures that have been implemented at this Command and havs en- hanced productivity are: - Power floor cleaners Pneumatic/ hydraulic ram tire

  12. Export of Ice-Cavity Water from Pine Island Ice Shelf, West Antarctica

    Science.gov (United States)

    Thurnherr, Andreas; Jacobs, Stanley; Dutrieux, Pierre

    2013-04-01

    significant mean upward motion within the cove strongly suggests that the upwelling takes place within the highly fractured ice along the southern shear margin of the ice shelf. If so, the upwelling water is likely to contribute to both the volume of apparent "basal" melting and to the weakness of that shear margin.

  13. Sputtering of water ice

    International Nuclear Information System (INIS)

    Baragiola, R.A.; Vidal, R.A.; Svendsen, W.; Schou, J.; Shi, M.; Bahr, D.A.; Atteberrry, C.L.

    2003-01-01

    We present results of a range of experiments of sputtering of water ice together with a guide to the literature. We studied how sputtering depends on the projectile energy and fluence, ice growth temperature, irradiation temperature and external electric fields. We observed luminescence from the decay of H(2p) atoms sputtered by heavy ion impact, but not bulk ice luminescence. Radiolyzed ice does not sputter under 3.7 eV laser irradiation

  14. A Backscattering and Propagation Model for Radar Sounding of Ice Sheets

    DEFF Research Database (Denmark)

    Dall, Jørgen

    2016-01-01

    . The scattering and propagation properties of the icesheets are characterized using an empirical approach. The model comprises surface scattering from the air/ice interfaceand the ice/bed interface as well as volume scattering from the firn and the ice. Also specular reflection from the internal layers is modeled...

  15. Satellite-derived ice data sets no. 2: Arctic monthly average microwave brightness temperatures and sea ice concentrations, 1973-1976

    Science.gov (United States)

    Parkinson, C. L.; Comiso, J. C.; Zwally, H. J.

    1987-01-01

    A summary data set for four years (mid 70's) of Arctic sea ice conditions is available on magnetic tape. The data include monthly and yearly averaged Nimbus 5 electrically scanning microwave radiometer (ESMR) brightness temperatures, an ice concentration parameter derived from the brightness temperatures, monthly climatological surface air temperatures, and monthly climatological sea level pressures. All data matrices are applied to 293 by 293 grids that cover a polar stereographic map enclosing the 50 deg N latitude circle. The grid size varies from about 32 X 32 km at the poles to about 28 X 28 km at 50 deg N. The ice concentration parameter is calculated assuming that the field of view contains only open water and first-year ice with an ice emissivity of 0.92. To account for the presence of multiyear ice, a nomogram is provided relating the ice concentration parameter, the total ice concentration, and the fraction of the ice cover which is multiyear ice.

  16. Discrete Surface Evolution and Mesh Deformation for Aircraft Icing Applications

    Science.gov (United States)

    Thompson, David; Tong, Xiaoling; Arnoldus, Qiuhan; Collins, Eric; McLaurin, David; Luke, Edward; Bidwell, Colin S.

    2013-01-01

    Robust, automated mesh generation for problems with deforming geometries, such as ice accreting on aerodynamic surfaces, remains a challenging problem. Here we describe a technique to deform a discrete surface as it evolves due to the accretion of ice. The surface evolution algorithm is based on a smoothed, face-offsetting approach. We also describe a fast algebraic technique to propagate the computed surface deformations into the surrounding volume mesh while maintaining geometric mesh quality. Preliminary results presented here demonstrate the ecacy of the approach for a sphere with a prescribed accretion rate, a rime ice accretion, and a more complex glaze ice accretion.

  17. Analysis of the total system life cycle cost for the Civilian Radioactive Waste Management Program. Volume 1. The analysis and its results

    International Nuclear Information System (INIS)

    1986-04-01

    The total-system life-cycle cost (TSLCC) analysis for the Department of Energy's (DOE) Civilian Radioactive Waste Management Program is an ongoing activity that helps determine whether the revenue-producing mechanism established by the Nuclear Waste Policy Act of 1982 is sufficient to cover the cost of the program. This report provides cost estimates for the fourth evaluation of the adequacy of the fee. The total-system cost for the reference authorized-system program is estimated to be 24 to 32 billion (1985) dollars. The total-system cost for the reference improved-performance system is estimated to be 26 to 34 billion dollars. A number of sensitivity cases were analyzed. For the authorized system, the costs for the sensitivity cases studied range from 21 to 39 billion dollars. For the improved-performance system, which includes a facility for monitored retrievable storage, the total-system cost in the sensitivity cases is estimated to be as high as 41 billion dollars. The factors that affect costs more than any other single factor for both the authorized and the improved-performance systems are delays in repository startup. A preliminary analysis of the impact of extending the burnup of nuclear fuel in the reactor was also performed; its results indicate that the impact is insignificant: the total-system cost is essentially unchanged from the comparable constant-burnup cases. The current estimate of the the total-system cost for the reference authorized system is zero to 3 billion dollars (9%) higher than the estimate for the reference system in the January 1985 TSLCC analysis

  18. Cascading water underneath Wilkes Land, East Antarctic ice sheet, observed using altimetry and digital elevation models

    Science.gov (United States)

    Flament, T.; Berthier, E.; Rémy, F.

    2014-04-01

    We describe a major subglacial lake drainage close to the ice divide in Wilkes Land, East Antarctica, and the subsequent cascading of water underneath the ice sheet toward the coast. To analyse the event, we combined altimetry data from several sources and subglacial topography. We estimated the total volume of water that drained from Lake CookE2 by differencing digital elevation models (DEM) derived from ASTER and SPOT5 stereo imagery acquired in January 2006 and February 2012. At 5.2 ± 1.5 km3, this is the largest single subglacial drainage event reported so far in Antarctica. Elevation differences between ICESat laser altimetry spanning 2003-2009 and the SPOT5 DEM indicate that the discharge started in November 2006 and lasted approximately 2 years. A 13 m uplift of the surface, corresponding to a refilling of about 0.6 ± 0.3 km3, was observed between the end of the discharge in October 2008 and February 2012. Using the 35-day temporal resolution of Envisat radar altimetry, we monitored the subsequent filling and drainage of connected subglacial lakes located downstream of CookE2. The total volume of water traveling within the theoretical 500-km-long flow paths computed with the BEDMAP2 data set is similar to the volume that drained from Lake CookE2, and our observations suggest that most of the water released from Lake CookE2 did not reach the coast but remained trapped underneath the ice sheet. Our study illustrates how combining multiple remote sensing techniques allows monitoring of the timing and magnitude of subglacial water flow beneath the East Antarctic ice sheet.

  19. Variational Ridging in Sea Ice Models

    Science.gov (United States)

    Roberts, A.; Hunke, E. C.; Lipscomb, W. H.; Maslowski, W.; Kamal, S.

    2017-12-01

    This work presents the results of a new development to make basin-scale sea ice models aware of the shape, porosity and extent of individual ridges within the pack. We have derived an analytic solution for the Euler-Lagrange equation of individual ridges that accounts for non-conservative forces, and therefore the compressive strength of individual ridges. Because a region of the pack is simply a collection of paths of individual ridges, we are able to solve the Euler-Lagrange equation for a large-scale sea ice field also, and therefore the compressive strength of a region of the pack that explicitly accounts for the macro-porosity of ridged debris. We make a number of assumptions that have simplified the problem, such as treating sea ice as a granular material in ridges, and assuming that bending moments associated with ridging are perturbations around an isostatic state. Regardless of these simplifications, the ridge model is remarkably predictive of macro-porosity and ridge shape, and, because our equations are analytic, they do not require costly computations to solve the Euler-Lagrange equation of ridges on the large scale. The new ridge model is therefore applicable to large-scale sea ice models. We present results from this theoretical development, as well as plans to apply it to the Regional Arctic System Model and a community sea ice code. Most importantly, the new ridging model is particularly useful for pinpointing gaps in our observational record of sea ice ridges, and points to the need for improved measurements of the evolution of porosity of deformed ice in the Arctic and Antarctic. Such knowledge is not only useful for improving models, but also for improving estimates of sea ice volume derived from altimetric measurements of sea ice freeboard.

  20. Ice ages and nuclear waste disposal

    International Nuclear Information System (INIS)

    Ahonen, L.; Ruskeeniemi, T.; Luukkonen, A.; Pitkaenen, P.; Rasilainen, K.

    2002-01-01

    This report is an overview of Quaternary Ice Age and its potential consequences for nuclear waste disposal. Geological information on past climatic changes is shortly reviewed, based on the following records: geomorphological information, loessic deposits, deep-sea carbonate sediments, ice-core records, and continental calcite precipitates. Even though the present 'Great Ice Age' has lasted more that two million years, the present variation in cycles of about 100 000 years seems to have commenced only about 600 - 700 thousands years ago. According to the present understanding, southern Finland was during a major span of Weichsel free of continental ice sheet. However, the conditions may have been very cold, periglacial, when the continental ice sheet covered the Caledonian mountains and large areas of central Fennoscandia. The last glacial maximum of Weichsel glaciation was shorter than estimated earlier. Periglacial conditions are characterized by deep permafrost, reaching even the depth of nuclear waste disposal. Calculations of the advancement of permafrost indicate that the permafrost-front may reach the depth of about 500 meters in less than 10 000 years. The crust beneath the continental ice cover depresses, and rebounds when the ice sheet retreats. During the most intensive vertical movement of the crust, some crush zones may be activated and bedrock movements may take place along them. Due to the growth of ice sheets, ocean water table also depresses during glacial maximum, thus changing hydrogeological conditions in non-glaciated terrains. Increase in global ice volume is manifested in the stable oxygen and hydrogen isotope ratios. Based on isotope signals, as well other hydrogeochemical interpretation methods, indications of the earlier glaciations have been recognized in present groundwaters. (orig.)

  1. Light Scattering by Ice Crystals Containing Air Bubbles

    Science.gov (United States)

    Zhang, J.; Panetta, R. L.; Yang, P.; Bi, L.

    2014-12-01

    The radiative effects of ice clouds are often difficult to estimate accurately, but are very important for interpretation of observations and for climate modeling. Our understanding of these effects is primarily based on scattering calculations, but due to the variability in ice habit it is computationally difficult to determine the required scattering and absorption properties, and the difficulties are only compounded by the need to include consideration of air and carbon inclusions of the sort frequently observed in collected samples. Much of the previous work on effects of inclusions in ice particles on scattering properties has been conducted with variants of geometric optics methods. We report on simulations of scattering by ice crystals with enclosed air bubbles using the pseudo-spectral time domain method (PSTD) and improved geometric optics method (IGOM). A Bouncing Ball Model (BBM) is proposed as a parametrization of air bubbles, and the results are compared with Monte Carlo radiative transfer calculations. Consistent with earlier studies, we find that air inclusions lead to a smoothing of variations in the phase function, weakening of halos, and a reduction of backscattering. We extend these studies by examining the effects of the particular arrangement of a fixed number of bubbles, as well as the effects of splitting a given number of bubbles into a greater number of smaller bubbles with the same total volume fraction. The result shows that the phase function will not change much for stochastic distributed air bubbles. It also shows that local maxima of phase functions are smoothed out for backward directions, when we break bubbles into small ones, single big bubble scatter favors more forward scattering than multi small internal scatters.

  2. Helicopter Icing Review.

    Science.gov (United States)

    1980-09-01

    helicopter (i.e. in an icing tunnel or engine test cell ) and therefore can be subjected to controlled icing where spe- cific problems can be safely...evaluation. 69 2.2.5.2 Ice Protection Systems Demonstration Many of the systems noted in 2.2.5.1 can be evaluated in icing test cells or icing wind tunnels...Figure 2-32 illustrates a typical rotor deice system control arrangement. 104 (N >4 A.dO INaH -E- C4) uo U En 9 E-1 H m I ~z O 04 04iH U 0 El4 E-f C E

  3. Total Thyroidectomy

    Directory of Open Access Journals (Sweden)

    Lopez Moris E

    2016-06-01

    Full Text Available Total thyroidectomy is a surgery that removes all the thyroid tissue from the patient. The suspect of cancer in a thyroid nodule is the most frequent indication and it is presume when previous fine needle puncture is positive or a goiter has significant volume increase or symptomes. Less frequent indications are hyperthyroidism when it is refractory to treatment with Iodine 131 or it is contraindicated, and in cases of symptomatic thyroiditis. The thyroid gland has an important anatomic relation whith the inferior laryngeal nerve and the parathyroid glands, for this reason it is imperative to perform extremely meticulous dissection to recognize each one of these elements and ensure their preservation. It is also essential to maintain strict hemostasis, in order to avoid any postoperative bleeding that could lead to a suffocating neck hematoma, feared complication that represents a surgical emergency and endangers the patient’s life.It is essential to run a formal technique, without skipping steps, and maintain prudence and patience that should rule any surgical act.

  4. Ice slurry applications

    Energy Technology Data Exchange (ETDEWEB)

    Kauffeld, M. [Karlsruhe University of Applied Sciences, Moltkestr. 30, 76133 Karlsruhe (Germany); Wang, M.J.; Goldstein, V. [Sunwell Technologies Inc., 180 Caster Avenue, Woodbridge, L4L 5Y (Canada); Kasza, K.E. [Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States)

    2010-12-15

    The role of secondary refrigerants is expected to grow as the focus on the reduction of greenhouse gas emissions increases. The effectiveness of secondary refrigerants can be improved when phase changing media are introduced in place of single-phase media. Operating at temperatures below the freezing point of water, ice slurry facilitates several efficiency improvements such as reductions in pumping energy consumption as well as lowering the required temperature difference in heat exchangers due to the beneficial thermo-physical properties of ice slurry. Research has shown that ice slurry can be engineered to have ideal ice particle characteristics so that it can be easily stored in tanks without agglomeration and then be extractable for pumping at very high ice fraction without plugging. In addition ice slurry can be used in many direct contact food and medical protective cooling applications. This paper provides an overview of the latest developments in ice slurry technology. (author)

  5. Fundamental Ice Crystal Accretion Physics Studies

    Science.gov (United States)

    Struk, Peter M.; Broeren, Andy P.; Tsao, Jen-Ching; Vargas, Mario; Wright, William B.; Currie, Tom; Knezevici, Danny; Fuleki, Dan

    2012-01-01

    Due to numerous engine power-loss events associated with high-altitude convective weather, ice accretion within an engine due to ice crystal ingestion is being investigated. The National Aeronautics and Space Administration (NASA) and the National Research Council (NRC) of Canada are starting to examine the physical mechanisms of ice accretion on surfaces exposed to ice-crystal and mixed-phase conditions. In November 2010, two weeks of testing occurred at the NRC Research Altitude Facility utilizing a single wedge-type airfoil designed to facilitate fundamental studies while retaining critical features of a compressor stator blade or guide vane. The airfoil was placed in the NRC cascade wind tunnel for both aerodynamic and icing tests. Aerodynamic testing showed excellent agreement compared with CFD data on the icing pressure surface and allowed calculation of heat transfer coefficients at various airfoil locations. Icing tests were performed at Mach numbers of 0.2 to 0.3, total pressures from 93 to 45 kPa, and total temperatures from 5 to 15 C. Ice and liquid water contents ranged up to 20 and 3 g/m3, respectively. The ice appeared well adhered to the surface in the lowest pressure tests (45 kPa) and, in a particular case, showed continuous leading-edge ice growth to a thickness greater than 15 mm in 3 min. Such widespread deposits were not observed in the highest pressure tests, where the accretions were limited to a small area around the leading edge. The suction surface was typically ice-free in the tests at high pressure, but not at low pressure. The icing behavior at high and low pressure appeared to be correlated with the wet-bulb temperature, which was estimated to be above 0 C in tests at 93 kPa and below 0 C in tests at lower pressure, the latter enhanced by more evaporative cooling of water. The authors believe that the large ice accretions observed in the low pressure tests would undoubtedly cause the aerodynamic performance of a compressor component

  6. Autonomous Aerial Ice Observation for Ice Defense

    Directory of Open Access Journals (Sweden)

    Joakim Haugen

    2014-10-01

    Full Text Available One of the tasks in ice defense is to gather information about the surrounding ice environment using various sensor platforms. In this manuscript we identify two monitoring tasks known in literature, namely dynamic coverage and target tracking, and motivate how these tasks are relevant in ice defense using RPAS. An optimization-based path planning concept is outlined for solving these tasks. A path planner for the target tracking problem is elaborated in more detail and a hybrid experiment, which consists of both a real fixed-wing aircraft and simulated objects, is included to show the applicability of the proposed framework.

  7. Estimates of ikaite export from sea ice to the underlying seawater in a sea ice-seawater mesocosm

    Science.gov (United States)

    Geilfus, Nicolas-Xavier; Galley, Ryan J.; Else, Brent G. T.; Campbell, Karley; Papakyriakou, Tim; Crabeck, Odile; Lemes, Marcos; Delille, Bruno; Rysgaard, Søren

    2016-09-01

    The precipitation of ikaite and its fate within sea ice is still poorly understood. We quantify temporal inorganic carbon dynamics in sea ice from initial formation to its melt in a sea ice-seawater mesocosm pool from 11 to 29 January 2013. Based on measurements of total alkalinity (TA) and total dissolved inorganic carbon (TCO2), the main processes affecting inorganic carbon dynamics within sea ice were ikaite precipitation and CO2 exchange with the atmosphere. In the underlying seawater, the dissolution of ikaite was the main process affecting inorganic carbon dynamics. Sea ice acted as an active layer, releasing CO2 to the atmosphere during the growth phase, taking up CO2 as it melted and exporting both ikaite and TCO2 into the underlying seawater during the whole experiment. Ikaite precipitation of up to 167 µmol kg-1 within sea ice was estimated, while its export and dissolution into the underlying seawater was responsible for a TA increase of 64-66 µmol kg-1 in the water column. The export of TCO2 from sea ice to the water column increased the underlying seawater TCO2 by 43.5 µmol kg-1, suggesting that almost all of the TCO2 that left the sea ice was exported to the underlying seawater. The export of ikaite from the ice to the underlying seawater was associated with brine rejection during sea ice growth, increased vertical connectivity in sea ice due to the upward percolation of seawater and meltwater flushing during sea ice melt. Based on the change in TA in the water column around the onset of sea ice melt, more than half of the total ikaite precipitated in the ice during sea ice growth was still contained in the ice when the sea ice began to melt. Ikaite crystal dissolution in the water column kept the seawater pCO2 undersaturated with respect to the atmosphere in spite of increased salinity, TA and TCO2 associated with sea ice growth. Results indicate that ikaite export from sea ice and its dissolution in the underlying seawater can potentially hamper

  8. Arctic landfast sea ice

    Science.gov (United States)

    Konig, Christof S.

    Landfast ice is sea ice which forms and remains fixed along a coast, where it is attached either to the shore, or held between shoals or grounded icebergs. Landfast ice fundamentally modifies the momentum exchange between atmosphere and ocean, as compared to pack ice. It thus affects the heat and freshwater exchange between air and ocean and impacts on the location of ocean upwelling and downwelling zones. Further, the landfast ice edge is essential for numerous Arctic mammals and Inupiat who depend on them for their subsistence. The current generation of sea ice models is not capable of reproducing certain aspects of landfast ice formation, maintenance, and disintegration even when the spatial resolution would be sufficient to resolve such features. In my work I develop a new ice model that permits the existence of landfast sea ice even in the presence of offshore winds, as is observed in mature. Based on viscous-plastic as well as elastic-viscous-plastic ice dynamics I add tensile strength to the ice rheology and re-derive the equations as well as numerical methods to solve them. Through numerical experiments on simplified domains, the effects of those changes are demonstrated. It is found that the modifications enable landfast ice modeling, as desired. The elastic-viscous-plastic rheology leads to initial velocity fluctuations within the landfast ice that weaken the ice sheet and break it up much faster than theoretically predicted. Solving the viscous-plastic rheology using an implicit numerical method avoids those waves and comes much closer to theoretical predictions. Improvements in landfast ice modeling can only verified in comparison to observed data. I have extracted landfast sea ice data of several decades from several sources to create a landfast sea ice climatology that can be used for that purpose. Statistical analysis of the data shows several factors that significantly influence landfast ice distribution: distance from the coastline, ocean depth, as

  9. Modelling the contribution of supraglacial ice cliffs to the mass-balance of glaciers in the Langtang catchment, Nepalese Himalaya

    Science.gov (United States)

    Buri, P.; Steiner, J. F.; Miles, E.; Ragettli, S.; Pellicciotti, F.

    2017-12-01

    -cliffs to total glacier mass-balance, and shows that the volume lost by backwasting of ice cliffs is a non-negligible term in the total glacier mass balance of debris-covered glaciers, providing a partial explanation of the higher-than-expected mass losses of debris-covered glaciers of High Mountain Asia.

  10. Volumetry based biomarker speed of growth: Quantifying the change of total tumor volume in whole-body magnetic resonance imaging over time improves risk stratification of smoldering multiple myeloma patients.

    Science.gov (United States)

    Wennmann, Markus; Kintzelé, Laurent; Piraud, Marie; Menze, Bjoern H; Hielscher, Thomas; Hofmanninger, Johannes; Wagner, Barbara; Kauczor, Hans-Ulrich; Merz, Maximilian; Hillengass, Jens; Langs, Georg; Weber, Marc-André

    2018-05-18

    The purpose of this study was to improve risk stratification of smoldering multiple myeloma patients, introducing new 3D-volumetry based imaging biomarkers derived from whole-body MRI. Two-hundred twenty whole-body MRIs from 63 patients with smoldering multiple myeloma were retrospectively analyzed and all focal lesions >5mm were manually segmented for volume quantification. The imaging biomarkers total tumor volume, speed of growth (development of the total tumor volume over time), number of focal lesions, development of the number of focal lesions over time and the recent imaging biomarker '>1 focal lesion' of the International Myeloma Working Group were compared, taking 2-year progression rate, sensitivity and false positive rate into account. Speed of growth, using a cutoff of 114mm 3 /month, was able to isolate a high-risk group with a 2-year progression rate of 82.5%. Additionally, it showed by far the highest sensitivity in this study and in comparison to other biomarkers in the literature, detecting 63.2% of patients who progress within 2 years. Furthermore, its false positive rate (8.7%) was much lower compared to the recent imaging biomarker '>1 focal lesion' of the International Myeloma Working Group. Therefore, speed of growth is the preferable imaging biomarker for risk stratification of smoldering multiple myeloma patients.

  11. Validation Ice Crystal Icing Engine Test in the Propulsion Systems Laboratory at NASA Glenn Research Center

    Science.gov (United States)

    Oliver, Michael J.

    2014-01-01

    The Propulsion Systems Laboratory (PSL) is an existing altitude simulation jet engine test facility located at NASA Glenn Research Center in Cleveland, OH. It was modified in 2012 with the integration of an ice crystal cloud generation system. This paper documents the inaugural ice crystal cloud test in PSL--the first ever full scale, high altitude ice crystal cloud turbofan engine test to be conducted in a ground based facility. The test article was a Lycoming ALF502-R5 high bypass turbofan engine, serial number LF01. The objectives of the test were to validate the PSL ice crystal cloud calibration and engine testing methodologies by demonstrating the capability to calibrate and duplicate known flight test events that occurred on the same LF01 engine and to generate engine data to support fundamental and computational research to investigate and better understand the physics of ice crystal icing in a turbofan engine environment while duplicating known revenue service events and conducting test points while varying facility and engine parameters. During PSL calibration testing it was discovered than heated probes installed through tunnel sidewalls experienced ice buildup aft of their location due to ice crystals impinging upon them, melting and running back. Filtered city water was used in the cloud generation nozzle system to provide ice crystal nucleation sites. This resulted in mineralization forming on flow path hardware that led to a chronic degradation of performance during the month long test. Lacking internal flow path cameras, the response of thermocouples along the flow path was interpreted as ice building up. Using this interpretation, a strong correlation between total water content (TWC) and a weaker correlation between median volumetric diameter (MVD) of the ice crystal cloud and the rate of ice buildup along the instrumented flow path was identified. For this test article the engine anti-ice system was required to be turned on before ice crystal

  12. [Fuel Rod Consolidation Project]: The estimated total life cycle cost for the 30-year operation of prototypical consolidation demonstration equipment: Volume 4, Phase 2

    International Nuclear Information System (INIS)

    1987-01-01

    The Total Life Cycle Costs have been developed for the construction, operation and decommissioning of a single line of hot-cell-enclosed production consolidation equipment operating on spent fuel at the rate of 750 MTU/year for 30 years. The cost estimate is for a single production line that is part of an overall facility at either a Monitored Retrievable Storage or a Repository facility. This overall facility would include other capabilities and possibly other consolidation lines. However, no costs were included in the cost estimate for other portions of the plant, except that staff costs include an overhead charge that reflects the overhead support services in an overall facility

  13. Ice Lens Formation and Frost Heave at the Phoenix Landing Site

    Science.gov (United States)

    Zent, A. P.; Sizemore, H. G.; Remple, A. W.

    2011-01-01

    Several lines of evidence indicate that the volume of shallow ground ice in the martian high latitudes exceeds the pore volume of the host regolith. Boynton et al. found an optimal fit to the Mars Odyssey Gamma Ray Spectrometer (GRS) data at the Phoenix landing site by modeling a buried layer of 50-75% ice by mass (up to 90% ice by volume). Thermal and optical observations of recent impact craters in the northern hemisphere have revealed nearly pure ice. Ice deposits containing only 1-2% soil by volume were excavated by Phoenix. The leading hypothesis for the origin of this excess ice is that it developed in situ by a mechanism analogous to the formation of terrestrial ice lenses and needle ice. Problematically, terrestrial soil-ice segregation is driven by freeze/thaw cycling and the movement of bulk water, neither of which are expected to have occurred in the geologically recent past on Mars. If however ice lens formation is possible at temperatures less than 273 K, there are possible implications for the habitability of Mars permafrost, since the same thin films of unfrozen water that lead to ice segregation are used by terrestrial psychrophiles to metabolize and grow down to temperatures of at least 258 K.

  14. Removable cruciform for ice condenser ice basket

    International Nuclear Information System (INIS)

    Scrabis, C.M.; Mazza, G.E.; Golick, L.R.; Pomaibo, P.

    1987-01-01

    A removable cruciform for use in an ice basket having a generally cylindrical sidewall defining a central, vertical axis of the ice basket and plural, generally annular retaining rings secured to the interior of the cylindrical sidewall of the ice basket at predetermined, spaced elevations throughout the axial height of the ice basket is described comprising: a pair of brackets, each comprising a central, base portion having parallel longitudinal edges and a pair of integral legs extending at corresponding angles relative to the base portion from the perspective parallel longitudinal edges thereof; a pair of support plate assemblies secured to and extending in parallel, spaced relationship from one of the pair of brackets; a pair of slide support plates secured to the other of the pair of brackets and extending therefrom in spaced, parallel relationship; and spring means received within the housing and engaging the base portions of the brackets and applying a resilient biasing force thereto for maintaining the spaced relationship thereof

  15. Ice cream structure modification by ice-binding proteins.

    Science.gov (United States)

    Kaleda, Aleksei; Tsanev, Robert; Klesment, Tiina; Vilu, Raivo; Laos, Katrin

    2018-04-25

    Ice-binding proteins (IBPs), also known as antifreeze proteins, were added to ice cream to investigate their effect on structure and texture. Ice recrystallization inhibition was assessed in the ice cream mixes using a novel accelerated microscope assay and the ice cream microstructure was studied using an ice crystal dispersion method. It was found that adding recombinantly produced fish type III IBPs at a concentration 3 mg·L -1 made ice cream hard and crystalline with improved shape preservation during melting. Ice creams made with IBPs (both from winter rye, and type III IBP) had aggregates of ice crystals that entrapped pockets of the ice cream mixture in a rigid network. Larger individual ice crystals and no entrapment in control ice creams was observed. Based on these results a model of ice crystals aggregates formation in the presence of IBPs was proposed. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Parameterizing Size Distribution in Ice Clouds

    Energy Technology Data Exchange (ETDEWEB)

    DeSlover, Daniel; Mitchell, David L.

    2009-09-25

    cloud optical properties formulated in terms of PSD parameters in combination with remote measurements of thermal radiances to characterize the small mode. This is possible since the absorption efficiency (Qabs) of small mode crystals is larger at 12 µm wavelength relative to 11 µm wavelength due to the process of wave resonance or photon tunneling more active at 12 µm. This makes the 12/11 µm absorption optical depth ratio (or equivalently the 12/11 µm Qabs ratio) a means for detecting the relative concentration of small ice particles in cirrus. Using this principle, this project tested and developed PSD schemes that can help characterize cirrus clouds at each of the three ARM sites: SGP, NSA and TWP. This was the main effort of this project. These PSD schemes and ice sedimentation velocities predicted from them have been used to test the new cirrus microphysics parameterization in the GCM known as the Community Climate Systems Model (CCSM) as part of an ongoing collaboration with NCAR. Regarding the second problem, we developed and did preliminary testing on a passive thermal method for retrieving the total water path (TWP) of Arctic mixed phase clouds where TWPs are often in the range of 20 to 130 g m-2 (difficult for microwave radiometers to accurately measure). We also developed a new radar method for retrieving the cloud ice water content (IWC), which can be vertically integrated to yield the ice water path (IWP). These techniques were combined to determine the IWP and liquid water path (LWP) in Arctic clouds, and hence the fraction of ice and liquid water. We have tested this approach using a case study from the ARM field campaign called M-PACE (Mixed-Phase Arctic Cloud Experiment). This research led to a new satellite remote sensing method that appears promising for detecting low levels of liquid water in high clouds typically between -20 and -36 oC. We hope to develop this method in future research.

  17. Carbon dioxide enhances fragility of ice crystals

    International Nuclear Information System (INIS)

    Qin Zhao; Buehler, Markus J

    2012-01-01

    Ice caps and glaciers cover 7% of the Earth, greater than the land area of Europe and North America combined, and play an important role in global climate. The small-scale failure mechanisms of ice fracture, however, remain largely elusive. In particular, little understanding exists about how the presence and concentration of carbon dioxide molecules, a significant component in the atmosphere, affects the propensity of ice to fracture. Here we use atomic simulations with the first-principles based ReaxFF force field capable of describing the details of chemical reactions at the tip of a crack, applied to investigate the effects of the presence of carbon dioxide molecules on ice fracture. Our result shows that increasing concentrations of carbon dioxide molecules significantly decrease the fracture toughness of the ice crystal, making it more fragile. Using enhanced molecular sampling with metadynamics we reconstruct the free energy landscape in varied chemical microenvironments and find that carbon dioxide molecules affect the bonds between water molecules at the crack tip and decrease their strength by altering the dissociation energy of hydrogen bonds. In the context of glacier dynamics our findings may provide a novel viewpoint that could aid in understanding the breakdown and melting of glaciers, suggesting that the chemical composition of the atmosphere can be critical to mediate the large-scale motion of large volumes of ice.

  18. Efficient meltwater drainage through supraglacial streams and rivers on the southwest Greenland ice sheet.

    Science.gov (United States)

    Smith, Laurence C; Chu, Vena W; Yang, Kang; Gleason, Colin J; Pitcher, Lincoln H; Rennermalm, Asa K; Legleiter, Carl J; Behar, Alberto E; Overstreet, Brandon T; Moustafa, Samiah E; Tedesco, Marco; Forster, Richard R; LeWinter, Adam L; Finnegan, David C; Sheng, Yongwei; Balog, James

    2015-01-27

    Thermally incised meltwater channels that flow each summer across melt-prone surfaces of the Greenland ice sheet have received little direct study. We use high-resolution WorldView-1/2 satellite mapping and in situ measurements to characterize supraglacial water storage, drainage pattern, and discharge across 6,812 km(2) of southwest Greenland in July 2012, after a record melt event. Efficient surface drainage was routed through 523 high-order stream/river channel networks, all of which terminated in moulins before reaching the ice edge. Low surface water storage (3.6 ± 0.9 cm), negligible impoundment by supraglacial lakes or topographic depressions, and high discharge to moulins (2.54-2.81 cm⋅d(-1)) indicate that the surface drainage system conveyed its own storage volume every drainage to true outflow from the ice edge. However, Isortoq discharges tended lower than runoff simulations from the Modèle Atmosphérique Régional (MAR) regional climate model (0.056-0.112 km(3)⋅d(-1) vs. ∼0.103 km(3)⋅d(-1)), and when integrated over the melt season, totaled just 37-75% of MAR, suggesting nontrivial subglacial water storage even in this melt-prone region of the ice sheet. We conclude that (i) the interior surface of the ice sheet can be efficiently drained under optimal conditions, (ii) that digital elevation models alone cannot fully describe supraglacial drainage and its connection to subglacial systems, and (iii) that predicting outflow from climate models alone, without recognition of subglacial processes, may overestimate true meltwater export from the ice sheet to the ocean.

  19. Ultraviolet spectrophotometry of comet Giacobini-Zinner during the ICE encounter. [International Cometary Explorer (ICE)

    Science.gov (United States)

    Ahearn, Michael F.; Mcfadden, Lucy A.; Feldman, Paul D.; Boehnhardt, Hermann; Rahe, Juergen; Festou, Michael; Brandt, John C.; Maran, Stephen P.; Niedner, Malcom B.; Smith, Andrew M.

    1986-01-01

    The IUE spectrophotometry of Comet P/Giacobini-Zinner was acquired in support of the International Cometary Explorer (ICE) mission. The abundances (or upper limits) of UV-active species were calculated. During the ICE encounter the H2O production rate was 3 times 10 to the 28th power/sec, + or - 50%, consistent with values derived from the ICE experiments. Comparison of the abundance of CO2(+) ions with the total electron density measured by the plasma electron experiment on ICE indicates a deficiency of ions relative to electrons indicating a population of ions not detected by remote sensing. The absence of detectable Mg(+) rules out this species as a possible ion of M/Q = 24 detected by the Ion Composition Instrument, part of the ICE complement of instruments.

  20. Application of ozonated dry ice (ALIGAL™ Blue Ice) for packaging and transport in the food industry.

    Science.gov (United States)

    Fratamico, Pina M; Juneja, Vijay; Annous, Bassam A; Rasanayagam, Vasuhi; Sundar, M; Braithwaite, David; Fisher, Steven

    2012-05-01

    Dry ice is used by meat and poultry processors for temperature reduction during processing and for temperature maintenance during transportation. ALIGAL™ Blue Ice (ABI), which combines the antimicrobial effect of ozone (O(3)) along with the high cooling capacity of dry ice, was investigated for its effect on bacterial reduction in air, in liquid, and on food and glass surfaces. Through proprietary means, O(3) was introduced to produce dry ice pellets to a concentration of 20 parts per million (ppm) by total weight. The ABI sublimation rate was similar to that of dry ice pellets under identical conditions, and ABI was able to hold the O(3) concentration throughout the normal shelf life of the product. Challenge studies were performed using different microorganisms, including E. coli, Campylobacter jejuni, Salmonella, and Listeria, that are critical to food safety. ABI showed significant (P Food Technologists®

  1. A sensitivity analysis for a thermomechanical model of the Antarctic ice sheet and ice shelves

    Science.gov (United States)

    Baratelli, F.; Castellani, G.; Vassena, C.; Giudici, M.

    2012-04-01

    The outcomes of an ice sheet model depend on a number of parameters and physical quantities which are often estimated with large uncertainty, because of lack of sufficient experimental measurements in such remote environments. Therefore, the efforts to improve the accuracy of the predictions of ice sheet models by including more physical processes and interactions with atmosphere, hydrosphere and lithosphere can be affected by the inaccuracy of the fundamental input data. A sensitivity analysis can help to understand which are the input data that most affect the different predictions of the model. In this context, a finite difference thermomechanical ice sheet model based on the Shallow-Ice Approximation (SIA) and on the Shallow-Shelf Approximation (SSA) has been developed and applied for the simulation of the evolution of the Antarctic ice sheet and ice shelves for the last 200 000 years. The sensitivity analysis of the model outcomes (e.g., the volume of the ice sheet and of the ice shelves, the basal melt rate of the ice sheet, the mean velocity of the Ross and Ronne-Filchner ice shelves, the wet area at the base of the ice sheet) with respect to the model parameters (e.g., the basal sliding coefficient, the geothermal heat flux, the present-day surface accumulation and temperature, the mean ice shelves viscosity, the melt rate at the base of the ice shelves) has been performed by computing three synthetic numerical indices: two local sensitivity indices and a global sensitivity index. Local sensitivity indices imply a linearization of the model and neglect both non-linear and joint effects of the parameters. The global variance-based sensitivity index, instead, takes into account the complete variability of the input parameters but is usually conducted with a Monte Carlo approach which is computationally very demanding for non-linear complex models. Therefore, the global sensitivity index has been computed using a development of the model outputs in a

  2. Pan-Arctic sea ice-algal chl a biomass and suitable habitat are largely underestimated for multiyear ice.

    Science.gov (United States)

    Lange, Benjamin A; Flores, Hauke; Michel, Christine; Beckers, Justin F; Bublitz, Anne; Casey, John Alec; Castellani, Giulia; Hatam, Ido; Reppchen, Anke; Rudolph, Svenja A; Haas, Christian

    2017-11-01

    There is mounting evidence that multiyear ice (MYI) is a unique component of the Arctic Ocean and may play a more important ecological role than previously assumed. This study improves our understanding of the potential of MYI as a suitable habitat for sea ice algae on a pan-Arctic scale. We sampled sea ice cores from MYI and first-year sea ice (FYI) within the Lincoln Sea during four consecutive spring seasons. This included four MYI hummocks with a mean chl a biomass of 2.0 mg/m 2 , a value significantly higher than FYI and MYI refrozen ponds. Our results support the hypothesis that MYI hummocks can host substantial ice-algal biomass and represent a reliable ice-algal habitat due to the (quasi-) permanent low-snow surface of these features. We identified an ice-algal habitat threshold value for calculated light transmittance of 0.014%. Ice classes and coverage of suitable ice-algal habitat were determined from snow and ice surveys. These ice classes and associated coverage of suitable habitat were applied to pan-Arctic CryoSat-2 snow and ice thickness data products. This habitat classification accounted for the variability of the snow and ice properties and showed an areal coverage of suitable ice-algal habitat within the MYI-covered region of 0.54 million km 2 (8.5% of total ice area). This is 27 times greater than the areal coverage of 0.02 million km 2 (0.3% of total ice area) determined using the conventional block-model classification, which assigns single-parameter values to each grid cell and does not account for subgrid cell variability. This emphasizes the importance of accounting for variable snow and ice conditions in all sea ice studies. Furthermore, our results indicate the loss of MYI will also mean the loss of reliable ice-algal habitat during spring when food is sparse and many organisms depend on ice-algae. © 2017 The Authors. Global Change Biology Published by John Wiley & Sons Ltd.

  3. Amorphous ice. A microporous solid: astrophysical implications

    International Nuclear Information System (INIS)

    Mayer, E.; Pletzer, R.

    1987-01-01

    Vapour deposited amorphous ice, investigated by N 2 -adsorption at 77 K, was found to be a microporous solid. Micropore volumes between 0.21 and 0.12 cm 3 /g were determined by comparison plots and Dubinin-Radushkevich plots. Warming of the adsorbent to 113 K caused sintering and reduction of apparent surface area by about an order of magnitude; in the presence of adsorbed gas, large amounts of gas were enclosed in the solid. The influence of micropores on the H 2 recombination rate on amorphous ice in interstellar dust and on adsorption of volatile gases in comets is discussed briefly

  4. Microbiological Contamination of Ice Cream Commercially Available in Korea and its Irradiation Effect

    International Nuclear Information System (INIS)

    Yook, H.S.; Kim, H.J.; Jo, C.U.; Kim, D.S.; Byun, M.W.

    2005-01-01

    The microbial contamination of ice cream product commercially available in Korea was determined using ice bar, ice cream, ice milk and non-milk fat ice cream. Irradiation effect on enhancement of microbiological safety was also investigated at doses of 1, 3, and 5 kGy. In all products, yeast and molds were not detected, however, total aerobic and coliform bacteria were detected at 1~2 and 1~1.5 Log CFU/g level, respectively. According to the different flavor used in ice cream, total aerobic bacteria were detected as 2.30, 2.90, and 3.32 Log CFU/g level in vanilla, chocolate, and strawberry ice cream, respectively. Yeast and mold was not detected in vanilla ice cream but 2.30 and 2.70 Log CFU/g in chocolate and strawberry ice cream, respectively

  5. Optimal Electromagnetic (EM) Geophysical Techniques to Map the Concentration of Subsurface Ice and Adsorbed Water on Mars and the Moon

    Science.gov (United States)

    Stillman, D. E.; Grimm, R. E.

    2013-12-01

    Water ice is ubiquitous in our Solar System and is a probable target for planetary exploration. Mapping the lateral and vertical concentration of subsurface ice from or near the surface could determine the origin of lunar and martian ice and quantify a much-needed resource for human exploration. Determining subsurface ice concentration on Earth is not trivial and has been attempted previously with electrical resistivity tomography (ERT), ground penetrating radar (GPR), airborne EM (AEM), and nuclear magnetic resonance (NMR). These EM geophysical techniques do not actually detect ice, but rather the absence of unfrozen water. This causes a non-unique interpretation of frozen and dry subsurface sediments. This works well in the arctic because most locations are not dry. However, for planetary exploration, liquid water is exceedingly rare and subsurface mapping must discriminate between an ice-rich and a dry subsurface. Luckily, nature has provided a unique electrical signature of ice: its dielectric relaxation. The dielectric relaxation of ice creates a temperature and frequency dependence of the electrical properties and varies the relative dielectric permittivity from ~3.1 at radar frequencies to >100 at low frequencies. On Mars, sediments smaller than silt size can hold enough adsorbed unfrozen water to complicate the measurement. This is because the presence of absorbed water also creates frequency-dependent electrical properties. The dielectric relaxation of adsorbed water and ice can be separated as they have different shapes and frequency ranges as long as a spectrum spanning the two relaxations is measured. The volume concentration of ice and adsorbed water is a function of the strength of their relaxations. Therefore, we suggest that capacitively-coupled dielectric spectroscopy (a.k.a. spectral induced polarization or complex resistivity) can detect the concentration of both ice and adsorbed water in the subsurface. To prove this concept we have collected

  6. Aircraft Icing Handbook. (Update)

    Science.gov (United States)

    1993-01-01

    Report 1946-1947, U. S. Air Material Command Tech. Rept. 5676. Findeisen , W., *Meteorological Commentary of D (air) 1209, Icing,* Germany, Reichsamt fur...Wetterdienst, Forschungs-und Krfahrungsberichte, Ser. a, No. 29, 1943. Findeisen , W., *Meteorological-Physical Limitations of Icing on the Atmosphere...Apparatus for Measurement,’ Harvard - Mt. Washington Icing Research Report 1946-1947, U. S. Air Material Command Tech. Rept. 5676.. Findeisen , W., "The

  7. ASSESSMENT OF THE TOTAL PETROLEUM HYDROCARBON CONTENT OF AGRICULTURAL SOIL POLLUTED WITH DIFFERENT VOLUME OF CRUDE OIL DURING PLANT- MICROBE INTERACTION

    Directory of Open Access Journals (Sweden)

    Toochukwu Ekwutosi OGBULIE

    2014-06-01

    Full Text Available The effectiveness of plants in interaction with indigenous organisms in environmental clean –up was evaluated. The agricultural soil used for the study was polluted with 100ml, 200ml, 400ml and 800ml of Bonny light crude oil [100%]. Pre and post Microbial examination of the polluted soil identified the indigenous flora present in the soil to be Penicillum sp Aspergillus fumigatus, Aspergillus niger, Candida sp, Pseudomonas fluorescence, Acinetobacter baumanni, Bacillus mycoides, Klebsiella sp., Staphylococcus aureus and Escherichia coli though the absence of S aureus and E. coli was evident during the latter. Vigna unguiculata var unguiculata, Mucuna pruriens, Zea mays and Telfairia occidentalis were the test plant used. Gas chromatographic (GC analysis revealed the total petroleum hydrocarbon (TPH of polluted soil on comparison with the value of 10,380 kg/ mg for control sample, to be low. The high TPH obtained from samples polluted with higher concentration depicts that the numbers of plants to be cultivated for remediation could be a determining factor for a faster clean-up. Statistical analysis using analysis of variance (ANOVA model of SPSS software however, showed there was no significant difference in the degradation of crude oil in samples that are in the green house or field.

  8. Safe Loads on Ice Sheets (Ice Engineering. Number 13)

    National Research Council Canada - National Science Library

    Haynes, F. D; Carey, Kevin L; Cattabriga, Gioia

    1996-01-01

    Every winter, ice sheets that grow on lakes and rivers in northern states are used for ice roads, ice bridges, construction platforms, airstrips, and recreational activities, It becomes very important...

  9. Total protein

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/003483.htm Total protein To use the sharing features on this page, please enable JavaScript. The total protein test measures the total amount of two classes ...

  10. The Addition of Sago Flour in Yoghurt Based on Physical Propeties of Yoghurt Ice Cream

    Directory of Open Access Journals (Sweden)

    Ika Ayu Wijayanti

    2017-02-01

    Full Text Available The purpose of this research was to determine the best concentration of adding sago flour in yoghurt based on viscosity, overrun, melting rate and total solid of yoghurt ice cream. The experiment was designed by Completely Randomized Design (CRD using four treatments were 0 %, 2 %, 4 %, 6 % from volume of fresh milk and four replications. The data were analyzed by using Analysis of Variance (ANOVA and continued by Duncan’s Multiple Range Test (DMRT. Result of this research showed that concentration of adding sago flour in yoghurt gave highly significant difference effect (P<0.01 on viscosity, overrun, melting rate and total solid of yoghurt ice cream. It can be concluded that the adding of sago flour 2% in yoghurt gave the best result with the viscosity was 1750.75 cP, overrun was 25.14%, melting rate was 39.13 minutes/50 g, total solid was 36.20% and gave the best quality of yoghurt ice cream.

  11. Polarized Raman spectroscopic study of relaxed high density amorphous ices under pressure.

    Science.gov (United States)

    Suzuki, Yoshiharu; Tominaga, Yasunori

    2010-10-28

    We have made high density amorphous ice (HDA) by the pressure-induced amorphization of hexagonal ice at 77 K and measured the volume change on isobaric heating in a pressure range between 0.1 and 1.5 GPa. The volume of HDA on heating below ∼0.35 GPa increases, while the volume of HDA on heating above ∼0.35 GPa decreases. The polarized OH-stretching Raman spectra of the relaxed HDAs are compared with that of the unannealed HDA. The relaxed HDAs are prepared at 0.2 GPa at 130 K and 1.5 GPa at 160 K. It is found that the relatively strong totally symmetric OH-stretching vibration mode around 3100 cm(-1) exists in the depolarized reduced Raman spectrum χ(VH)(") of the unannealed HDA and that its intensity rapidly decreases by relaxation. The χ(VH)(") profiles of the relaxed HDA are similar to those of liquid water. These results indicate that the HDA reaches a nearly equilibrium state by annealing and the intrinsic state of HDA relates to a liquid state. The pressure-volume curve of the relaxed HDA at 140 K seems to be smooth in the pressure range below 1.5 GPa.

  12. Ice and ocean velocity in the Arctic marginal ice zone: Ice roughness and momentum transfer

    Directory of Open Access Journals (Sweden)

    Sylvia T. Cole

    2017-09-01

    Full Text Available The interplay between sea ice concentration, sea ice roughness, ocean stratification, and momentum transfer to the ice and ocean is subject to seasonal and decadal variations that are crucial to understanding the present and future air-ice-ocean system in the Arctic. In this study, continuous observations in the Canada Basin from March through December 2014 were used to investigate spatial differences and temporal changes in under-ice roughness and momentum transfer as the ice cover evolved seasonally. Observations of wind, ice, and ocean properties from four clusters of drifting instrument systems were complemented by direct drill-hole measurements and instrumented overhead flights by NASA operation IceBridge in March, as well as satellite remote sensing imagery about the instrument clusters. Spatially, directly estimated ice-ocean drag coefficients varied by a factor of three with rougher ice associated with smaller multi-year ice floe sizes embedded within the first-year-ice/multi-year-ice conglomerate. Temporal differences in the ice-ocean drag coefficient of 20–30% were observed prior to the mixed layer shoaling in summer and were associated with ice concentrations falling below 100%. The ice-ocean drag coefficient parameterization was found to be invalid in September with low ice concentrations and small ice floe sizes. Maximum momentum transfer to the ice occurred for moderate ice concentrations, and transfer to the ocean for the lowest ice concentrations and shallowest stratification. Wind work and ocean work on the ice were the dominant terms in the kinetic energy budget of the ice throughout the melt season, consistent with free drift conditions. Overall, ice topography, ice concentration, and the shallow summer mixed layer all influenced mixed layer currents and the transfer of momentum within the air-ice-ocean system. The observed changes in momentum transfer show that care must be taken to determine appropriate parameterizations

  13. Supporting evidence from the EPICA Dronning Maud Land ice core for atmospheric CO2 changes during the past millennium

    International Nuclear Information System (INIS)

    Siegenthaler, Urs; Monnin, Eric; Kawamura, Kenji; Spahni, Renato; Schwander, Jakob; Stauffer, Bernhard; Stocker, Thomas F.; Fischer, Hubertus

    2005-01-01

    The most direct method of investigating past variations of the atmospheric CO 2 concentration before 1958, when continuous direct atmospheric CO 2 measurements started, is the analysis of air extracted from suitable ice cores. Here we present a new detailed CO 2 record from the Dronning Maud Land (DML) ice core, drilled in the framework of the European Project for Ice Coring in Antarctica (EPICA) and some new measurements on a previously drilled ice core from the South Pole. The DML CO 2 record shows an increase from about 278 to 282 parts per million by volume (ppmv) between ad 1000 and ad 1200 and a fairly continuous decrease to a mean value of about 277 ppmv around ad 1700. While the new South Pole measurements agree well with DML at the minimum at ad 1700 they are on average about 2 ppmv lower during the period ad 1000-1500. Published measurements from the coastal high-accumulation site Law Dome are considered as very reliable because of the reproducibility of the measurements, high temporal resolution and an accurate time scale. Other Antarctic ice cores could not, or only partly, reproduce the pre-industrial measurements from Law Dome. A comparison of the trends of DML and Law Dome shows a general agreement. However we should be able to rule out co-variations caused by the same artefact. Two possible effects are discussed, first production of CO 2 by chemical reactions and second diffusion of dissolved air through the ice matrix into the bubbles. While the first effect cannot be totally excluded, comparison of the Law Dome and DML record shows that dissolved air diffusing to bubbles cannot be responsible for the pre-industrial variation. Therefore, the new record is not a proof of the Law Dome results but the first very strong support from an ice core of the Antarctic plateau

  14. Constraints on martian lobate debris apron evolution and rheology from numerical modeling of ice flow

    Science.gov (United States)

    Parsons, Reid A.; Nimmo, Francis; Miyamoto, Hideaki

    2011-07-01

    Radar observations in the Deuteronilus Mensae region by Mars Reconnaissance Orbiter have constrained the thickness and dust concentration found within mid-latitude ice deposits, providing an opportunity to more accurately estimate the rheology of ice responsible for the formation of lobate debris aprons based on their apparent age of ˜100 Myr. We developed a numerical model simulating ice flow under martian conditions using results from ice deformation experiments, theory of ice grain growth based on terrestrial ice cores, and observational constraints from radar profiles and laser altimetry. By varying the ice grain size, the ice temperature, the subsurface slope, and the initial ice volume we determine the combination of parameters that best reproduce the observed LDA lengths and thicknesses over a period of time comparable to the apparent ages of LDA surfaces (90-300 Myr). We find that an ice temperature of 205 K, an ice grain size of 5 mm, and a flat subsurface slope give reasonable ages for many LDAs in the northern mid-latitudes of Mars. Assuming that the ice grain size is limited by the grain boundary pinning effect of incorporated dust, these results limit the dust volume concentration to less than 4%. However, assuming all LDAs were emplaced by a single event, we find that there is no single combination of grain size, temperature, and subsurface slope which can give realistic ages for all LDAs, suggesting that some or all of these variables are spatially heterogeneous. Based on our model we conclude that the majority of northern mid-latitude LDAs are composed of clean (⩽4 vol%), coarse (⩾1 mm) grained ice, but regional differences in either the amount of dust mixed in with the ice, or in the presence of a basal slope below the LDA ice must be invoked. Alternatively, the ice temperature and/or timing of ice deposition may vary significantly between different mid-latitude regions. Either eventuality can be tested with future observations.

  15. Bacterial Ice Crystal Controlling Proteins

    Science.gov (United States)

    Lorv, Janet S. H.; Rose, David R.; Glick, Bernard R.

    2014-01-01

    Across the world, many ice active bacteria utilize ice crystal controlling proteins for aid in freezing tolerance at subzero temperatures. Ice crystal controlling proteins include both antifreeze and ice nucleation proteins. Antifreeze proteins minimize freezing damage by inhibiting growth of large ice crystals, while ice nucleation proteins induce formation of embryonic ice crystals. Although both protein classes have differing functions, these proteins use the same ice binding mechanisms. Rather than direct binding, it is probable that these protein classes create an ice surface prior to ice crystal surface adsorption. Function is differentiated by molecular size of the protein. This paper reviews the similar and different aspects of bacterial antifreeze and ice nucleation proteins, the role of these proteins in freezing tolerance, prevalence of these proteins in psychrophiles, and current mechanisms of protein-ice interactions. PMID:24579057

  16. Frozen waterfall (or ice cascade) growth and decay: a thermodynamic approach

    Science.gov (United States)

    Gauthier, Francis; Montagnat, Maurine; Weiss, Jérôme; Allard, Michel; Hétu, Bernard

    2013-04-01

    The ice volume evolution of an ice cascade was studied using a thermodynamic model. The model was developed from meteorological data collected in the vicinity of the waterfall and validated from ice volume measurements estimated from terrestrial LiDAR images. The ice cascade forms over a 45 m high rockwall located in northern Gaspésie, Québec, Canada. Two stages of formation were identified. During the first stage, the growth is mainly controlled by air convection around the flowing and freefalling water. The ice cascade growth rate increases with the decreasing air temperature below 0°C and when the water flow reaches its lowest level. During the second stage, the ice cascade covers the entire rockwall surface, water flow is isolated from the outside environment and ice volume increases asymptotically. Heat is evacuated from the water flow through the ice cover by conduction. The growth is mainly controlled by the radiation energy balance but more specifically by the longwave radiation emitted at the ice surface during the night. In spring, melting of the ice cascade is clearly dependant on the sensible heat carried by the increasing water flow and the diffuse solar radiation received at the ice surface during the day.

  17. Winter Arctic sea ice growth: current variability and projections for the coming decades

    Science.gov (United States)

    Petty, A.; Boisvert, L.; Webster, M.; Holland, M. M.; Bailey, D. A.; Kurtz, N. T.; Markus, T.

    2017-12-01

    Arctic sea ice increases in both extent and thickness during the cold winter months ( October to May). Winter sea ice growth is an important factor controlling ocean ventilation and winter water/deep water formation, as well as determining the state and vulnerability of the sea ice pack before the melt season begins. Key questions for the Arctic community thus include: (i) what is the current magnitude and variability of winter Arctic sea ice growth and (ii) how might this change in a warming Arctic climate? To address (i), our current best guess of pan-Arctic sea ice thickness, and thus volume, comes from satellite altimetry observations, e.g. from ESA's CryoSat-2 satellite. A significant source of uncertainty in these data come from poor knowledge of the overlying snow depth. Here we present new estimates of winter sea ice thickness from CryoSat-2 using snow depths from a simple snow model forced by reanalyses and satellite-derived ice drift estimates, combined with snow depth estimates from NASA's Operation IceBridge. To address (ii), we use data from the Community Earth System Model's Large Ensemble Project, to explore sea ice volume and growth variability, and how this variability might change over the coming decades. We compare and contrast the model simulations to observations and the PIOMAS ice-ocean model (over recent years/decades). The combination of model and observational analysis provide novel insight into Arctic sea ice volume variability.

  18. AURA-A radio frequency extension to IceCube

    International Nuclear Information System (INIS)

    Landsman, H.; Ruckman, L.; Varner, G.S.

    2009-01-01

    The excellent radio frequency (RF) transparency of cold polar ice, combined with the coherent Cherenkov emission produced by neutrino-induced showers when viewed at wavelengths longer than a few centimeters, has spurred considerable interest in a large-scale radio-wave neutrino detector array. The AURA (Askaryan Under-ice Radio Array) experimental effort, within the IceCube collaboration, seeks to take advantage of the opportunity presented by IceCube [A. Karle, Nucl. Instr. and Meth. A (2009), this issue, doi: (10.1016/j.nima.2009.03.180).; A. Achtenberg et al., The IceCube Collaboration, Astropart. Phys. 26 (2006) 155 ] drilling through 2010 to establish the RF technology needed to achieve 100-1000km 3 effective volumes. In the 2006-2007 Austral summer, three deep in-ice RF clusters were deployed at depths of ∼1300 and ∼300m on top of the IceCube strings. Additional three clusters will be deployed in the Austral summer of 2008-2009. Verification and calibration results from the current deployed clusters are presented, and the detector design and performances are discussed. Augmentation of IceCube with large-scale (1000km 3 sr) radio and acoustic arrays would extend the physics reach of IceCube into the EeV-ZeV regime and offer substantial technological redundancy.

  19. Ice-dynamic projections of the Greenland ice sheet in response to atmospheric and oceanic warming

    Directory of Open Access Journals (Sweden)

    J. J. Fürst

    2015-05-01

    Full Text Available Continuing global warming will have a strong impact on the Greenland ice sheet in the coming centuries. During the last decade (2000–2010, both increased melt-water runoff and enhanced ice discharge from calving glaciers have contributed 0.6 ± 0.1 mm yr−1 to global sea-level rise, with a relative contribution of 60 and 40% respectively. Here we use a higher-order ice flow model, spun up to present day, to simulate future ice volume changes driven by both atmospheric and oceanic temperature changes. For these projections, the flow model accounts for runoff-induced basal lubrication and ocean warming-induced discharge increase at the marine margins. For a suite of 10 atmosphere and ocean general circulation models and four representative concentration pathway scenarios, the projected sea-level rise between 2000 and 2100 lies in the range of +1.4 to +16.6 cm. For two low emission scenarios, the projections are conducted up to 2300. Ice loss rates are found to abate for the most favourable scenario where the warming peaks in this century, allowing the ice sheet to maintain a geometry close to the present-day state. For the other moderate scenario, loss rates remain at a constant level over 300 years. In any scenario, volume loss is predominantly caused by increased surface melting as the contribution from enhanced ice discharge decreases over time and is self-limited by thinning and retreat of the marine margin, reducing the ice–ocean contact area. As confirmed by other studies, we find that the effect of enhanced basal lubrication on the volume evolution is negligible on centennial timescales. Our projections show that the observed rates of volume change over the last decades cannot simply be extrapolated over the 21st century on account of a different balance of processes causing ice loss over time. Our results also indicate that the largest source of uncertainty arises from the surface mass balance and the underlying climate change

  20. Sputtering of water ice

    DEFF Research Database (Denmark)

    Baragiola, R.A.; Vidal, R.A.; Svendsen, W.

    2003-01-01

    We present results of a range of experiments of sputtering of water ice together with a guide to the literature. We studied how sputtering depends on the projectile energy and fluence, ice growth temperature, irradiation temperature and external electric fields. We observed luminescence from...

  1. Ice sheet in peril

    DEFF Research Database (Denmark)

    Hvidberg, Christine Schøtt

    2016-01-01

    Earth's large ice sheets in Greenland and Antarctica are major contributors to sea level change. At present, the Greenland Ice Sheet (see the photo) is losing mass in response to climate warming in Greenland (1), but the present changes also include a long-term response to past climate transitions...

  2. Turning into Ice

    Science.gov (United States)

    Pietsch, Renée B.; Hanlon, Regina; Bohland, Cynthia; Schmale, David G., III

    2016-01-01

    This article describes an interdisciplinary unit in which students explore biological "ice nucleation"--by particles that cause water to freeze at temperatures above -38°C--through the lens of the microbial ice nucleator "Pseudomonas syringae." Such This activity, which aligns with the "Next Generation Science…

  3. Preliminary Results From a Heavily Instrumented Engine Ice Crystal Icing Test in a Ground Based Altitude Test Facility

    Science.gov (United States)

    Flegel, Ashlie B.; Oliver, Michael J.

    2016-01-01

    Preliminary results from the heavily instrumented ALF502R-5 engine test conducted in the NASA Glenn Research Center Propulsion Systems Laboratory are discussed. The effects of ice crystal icing on a full scale engine is examined and documented. This same model engine, serial number LF01, was used during the inaugural icing test in the Propulsion Systems Laboratory facility. The uncommanded reduction of thrust (rollback) events experienced by this engine in flight were simulated in the facility. Limited instrumentation was used to detect icing on the LF01 engine. Metal temperatures on the exit guide vanes and outer shroud and the load measurement were the only indicators of ice formation. The current study features a similar engine, serial number LF11, which is instrumented to characterize the cloud entering the engine, detect/characterize ice accretion, and visualize the ice accretion in the region of interest. Data were acquired at key LF01 test points and additional points that explored: icing threshold regions, low altitude, high altitude, spinner heat effects, and the influence of varying the facility and engine parameters. For each condition of interest, data were obtained from some selected variations of ice particle median volumetric diameter, total water content, fan speed, and ambient temperature. For several cases the NASA in-house engine icing risk assessment code was used to find conditions that would lead to a rollback event. This study further helped NASA develop necessary icing diagnostic instrumentation, expand the capabilities of the Propulsion Systems Laboratory, and generate a dataset that will be used to develop and validate in-house icing prediction and risk mitigation computational tools. The ice accretion on the outer shroud region was acquired by internal video cameras. The heavily instrumented engine showed good repeatability of icing responses when compared to the key LF01 test points and during day-to-day operation. Other noticeable

  4. Aircraft Icing Weather Data Reporting and Dissemination System

    Science.gov (United States)

    Bass, Ellen J.; Minsk, Brian; Lindholm, Tenny; Politovich, Marcia; Reehorst, Andrew (Technical Monitor)

    2002-01-01

    The long-term operational concept of this research is to develop an onboard aircraft system that assesses and reports atmospheric icing conditions automatically and in a timely manner in order to improve aviation safety and the efficiency of aircraft operations via improved real-time and forecast weather products. The idea is to use current measurement capabilities on aircraft equipped with icing sensors and in-flight data communication technologies as a reporting source. Without requiring expensive avionics upgrades, aircraft data must be processed and available for downlink. Ideally, the data from multiple aircraft can then be integrated (along with other real-time and modeled data) on the ground such that aviation-centered icing hazard metrics for volumes of airspace can be assessed. As the effect of icing on different aircraft types can vary, the information should be displayed in meaningful ways such that multiple types of users can understand the information. That is, information must be presented in a manner to allow users to understand the icing conditions with respect to individual concerns and aircraft capabilities. This research provides progress toward this operational concept by: identifying an aircraft platform capable of digitally capturing, processing, and downlinking icing data; identifying the required in situ icing data processing; investigating the requirements for routing the icing data for use by weather products; developing an icing case study in order to gain insight into major air carrier needs; developing and prototyping icing display concepts based on the National Center for Atmospheric Research's existing diagnostic and forecast experimental icing products; and conducting a usability study for the prototyped icing display concepts.

  5. Modeling the summertime evolution of sea-ice melt ponds

    DEFF Research Database (Denmark)

    Lüthje, Mikael; Feltham, D.L.; Taylor, P.D.

    2006-01-01

    We present a mathematical model describing the summer melting of sea ice. We simulate the evolution of melt ponds and determine area coverage and total surface ablation. The model predictions are tested for sensitivity to the melt rate of unponded ice, enhanced melt rate beneath the melt ponds...

  6. GLERL Radiation Transfer Through Freshwater Ice

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Radiation transmittance (ratio of transmitted to incident radiation) through clear ice, refrozen slush ice and brash ice, from ice surface to ice-water interface in...

  7. Torque and Axial Loading Physics for Measuring Atmospheric Icing Load and Icing Rate

    OpenAIRE

    Mughal, Umair Najeeb; Virk, Muhammad Shakeel

    2015-01-01

    Measuring icing load and icing rate are important parameters for an atmospheric icing sensor. A new icing sensor has recently been designed and developed at Narvik University College for measuring atmospheric icing rate, icing load and icing type. Unlike the existing atmospheric icing sensors commercially available in market, which uses the axial loading for measuring icing load and icing rate, this new sensory system measures icing load and icing rate using the torque loading physics. The pe...

  8. Ice-skating and roller disco injuries in Dublin.

    Science.gov (United States)

    Horner, C.; McCabe, M. J.

    1984-01-01

    A comparative study was carried out on a series of 72 ice-skating and 57 roller skating injuries over a sixteen month period. The average patient age was 20.5 years in the ice-skating group and 16.5 years in the roller skating group. Females predominated in both groups accounting for 72% of ice-skaters injured and 77% of roller skaters injured. Ice-skaters sustained more serious injuries than roller skaters as was evident from the significant difference in fracture numbers in the two groups. Ice-skating fractures accounted for 40% of all injuries while roller skating fractures were only 14% of their total injuries. The majority of ice-skating fractures occurred in females. As a result of our study we recommended several preventative measures. Images p207-a p207-b PMID:6487948

  9. On the Arctic Ocean ice thickness response to changes in the external forcing

    Energy Technology Data Exchange (ETDEWEB)

    Stranne, Christian; Bjoerk, Goeran [University of Gothenburg, Department of Earth Sciences, Box 460, Goeteborg (Sweden)

    2012-12-15

    Submarine and satellite observations show that the Arctic Ocean ice cover has undergone a large thickness reduction and a decrease in the areal extent during the last decades. Here the response of the Arctic Ocean ice cover to changes in the poleward atmospheric energy transport, F{sub wall}, is investigated using coupled atmosphere-ice-ocean column models. Two models with highly different complexity are used in order to illustrate the importance of different internal processes and the results highlight the dramatic effects of the negative ice thickness - ice volume export feedback and the positive surface albedo feedback. The steady state ice thickness as a function of F{sub wall} is determined for various model setups and defines what we call ice thickness response curves. When a variable surface albedo and snow precipitation is included, a complex response curve appears with two distinct regimes: a perennial ice cover regime with a fairly linear response and a less responsive seasonal ice cover regime. The two regimes are separated by a steep transition associated with surface albedo feedback. The associated hysteresis is however small, indicating that the Arctic climate system does not have an irreversible tipping point behaviour related to the surface albedo feedback. The results are discussed in the context of the recent reduction of the Arctic sea ice cover. A new mechanism related to regional and temporal variations of the ice divergence within the Arctic Ocean is presented as an explanation for the observed regional variation of the ice thickness reduction. Our results further suggest that the recent reduction in areal ice extent and loss of multiyear ice is related to the albedo dependent transition between seasonal and perennial ice i.e. large areas of the Arctic Ocean that has previously been dominated by multiyear ice might have been pushed below a critical mean ice thickness, corresponding to the above mentioned transition, and into a state dominated

  10. High-resolution ice thickness and bed topography of a land-terminating section of the Greenland Ice Sheet

    DEFF Research Database (Denmark)

    Lindbäck, K.; Pettersson, R.; Doyle, S. H.

    2014-01-01

    We present ice thickness and bed topography maps with high spatial resolution (250 to 500 m) of a and-terminating section of the Greenland Ice Sheet derived from combined ground-based and airborne radar surveys. The data have a total area of ~12000 km2 and cover the whole ablation area of the out...

  11. Modelling the surface mass balance of the Greenland ice sheet and neighbouring ice caps : A dynamical and statistical downscaling approach

    NARCIS (Netherlands)

    Noël, B.P.Y.

    2018-01-01

    The Greenland ice sheet (GrIS) is the world’s second largest ice mass, storing about one tenth of the Earth’s freshwater. If totally melted, global sea level would rise by 7.4 m, affecting low-lying regions worldwide. Since the mid-1990s, increased atmospheric and oceanic temperatures have

  12. Elastic uplift in southeast Greenland due to rapid ice mass loss

    DEFF Research Database (Denmark)

    Khan, Shfaqat Abbas; Van dam, Tonie; Hamilton, Gordon S.

    2007-01-01

    The rapid unloading of ice from the southeastern sector of the Greenland ice sheet between 2001 and 2006 caused an elastic uplift of 35 mm at a GPS site in Kulusuk. Most of the uplift results from ice dynamic-induced volume losses on two nearby outlet glaciers. Volume loss from Helheim Glacier...... between 62N and 66N. Citation: Khan, S. A., J. Wahr, L. A. Stearns, G. S. Hamilton, T. van Dam, K. M. Larson, and O. Francis (2007), Elastic uplift in southeast Greenland due to rapid ice mass loss....

  13. Total algorithms

    NARCIS (Netherlands)

    Tel, G.

    We define the notion of total algorithms for networks of processes. A total algorithm enforces that a "decision" is taken by a subset of the processes, and that participation of all processes is required to reach this decision. Total algorithms are an important building block in the design of

  14. High Arctic Holocene temperature record from the Agassiz ice cap and Greenland ice sheet evolution.

    Science.gov (United States)

    Lecavalier, Benoit S; Fisher, David A; Milne, Glenn A; Vinther, Bo M; Tarasov, Lev; Huybrechts, Philippe; Lacelle, Denis; Main, Brittany; Zheng, James; Bourgeois, Jocelyne; Dyke, Arthur S

    2017-06-06

    We present a revised and extended high Arctic air temperature reconstruction from a single proxy that spans the past ∼12,000 y (up to 2009 CE). Our reconstruction from the Agassiz ice cap (Ellesmere Island, Canada) indicates an earlier and warmer Holocene thermal maximum with early Holocene temperatures that are 4-5 °C warmer compared with a previous reconstruction, and regularly exceed contemporary values for a period of ∼3,000 y. Our results show that air temperatures in this region are now at their warmest in the past 6,800-7,800 y, and that the recent rate of temperature change is unprecedented over the entire Holocene. The warmer early Holocene inferred from the Agassiz ice core leads to an estimated ∼1 km of ice thinning in northwest Greenland during the early Holocene using the Camp Century ice core. Ice modeling results show that this large thinning is consistent with our air temperature reconstruction. The modeling results also demonstrate the broader significance of the enhanced warming, with a retreat of the northern ice margin behind its present position in the mid Holocene and a ∼25% increase in total Greenland ice sheet mass loss (∼1.4 m sea-level equivalent) during the last deglaciation, both of which have implications for interpreting geodetic measurements of land uplift and gravity changes in northern Greenland.

  15. Investigations of the form and flow of ice sheets and glaciers using radio-echo sounding

    Energy Technology Data Exchange (ETDEWEB)

    Dowdeswell, J A; Evans, S [Scott Polar Research Institute, University of Cambridge, Cambridge CB2 1ER (United Kingdom)

    2004-10-01

    Radio-echo sounding (RES), utilizing a variety of radio frequencies, was developed to allow glaciologists to measure the thickness of ice sheets and glaciers. We review the nature of electromagnetic wave propagation in ice and snow, including the permittivity of ice, signal attenuation and volume scattering, along with reflection from rough and specular surfaces. The variety of instruments used in RES of polar ice sheets and temperate glaciers is discussed. The applications and insights that a knowledge of ice thickness, and the wider nature of the form and flow of ice sheets, provides are also considered. The thickest ice measured is 4.7 km in East Antarctica. The morphology of the Antarctic and Greenland ice sheets, and many of the smaller ice caps and glaciers of the polar regions, has been investigated using RES. These findings are being used in three-dimensional numerical models of the response of the cryosphere to environmental change. In addition, the distribution and character of internal and basal reflectors within ice sheets contains information on, for example, ice-sheet layering and its chrono-stratigraphic significance, and has enabled the discovery and investigation of large lakes beneath the Antarctic Ice Sheet. Today, RES from ground-based and airborne platforms remains the most effective tool for measuring ice thickness and internal character.

  16. Coulombic charge ice

    Science.gov (United States)

    McClarty, P. A.; O'Brien, A.; Pollmann, F.

    2014-05-01

    We consider a classical model of charges ±q on a pyrochlore lattice in the presence of long-range Coulomb interactions. This model first appeared in the early literature on charge order in magnetite [P. W. Anderson, Phys. Rev. 102, 1008 (1956), 10.1103/PhysRev.102.1008]. In the limit where the interactions become short ranged, the model has a ground state with an extensive entropy and dipolar charge-charge correlations. When long-range interactions are introduced, the exact degeneracy is broken. We study the thermodynamics of the model and show the presence of a correlated charge liquid within a temperature window in which the physics is well described as a liquid of screened charged defects. The structure factor in this phase, which has smeared pinch points at the reciprocal lattice points, may be used to detect charge ice experimentally. In addition, the model exhibits fractionally charged excitations ±q/2 which are shown to interact via a 1/r potential. At lower temperatures, the model exhibits a transition to a long-range ordered phase. We are able to treat the Coulombic charge ice model and the dipolar spin ice model on an equal footing by mapping both to a constrained charge model on the diamond lattice. We find that states of the two ice models are related by a staggering field which is reflected in the energetics of these two models. From this perspective, we can understand the origin of the spin ice and charge ice ground states as coming from a dipolar model on a diamond lattice. We study the properties of charge ice in an external electric field, finding that the correlated liquid is robust to the presence of a field in contrast to the case of spin ice in a magnetic field. Finally, we comment on the transport properties of Coulombic charge ice in the correlated liquid phase.

  17. Changes in body weight, C-reactive protein, and total adiponectin in non-obese women after 12 months of a small-volume, home-based exercise program.

    Science.gov (United States)

    Mediano, Mauro Felippe Felix; Neves, Fabiana Alves; Cunha, Alessandra Cordeiro de Souza Rodrigues; Souza, Erica Patricia Garcia de; Moura, Anibal Sanchez; Sichieri, Rosely

    2013-01-01

    Our objective was to evaluate the effects of small-volume, home-based exercise combined with slight caloric restriction on the inflammatory markers C-reactive protein and adiponectin. In total, 54 women were randomly assigned to one of two groups for exercise intervention: the control or home-based exercise groups. Weight, waist and hip circumferences, and inflammatory markers were measured at baseline and after 6 and 12 months. Women allocated to the home-based exercise group received a booklet explaining the physical exercises to be practiced at home at least 3 times per week, 40 minutes per session, at low-to-moderate intensity. All participants received dietary counseling aimed at reducing caloric intake by 100-300 calories per day, with a normal distribution of macro-nutrients (26-28% of energy as fat). Clinicaltrials.gov: NCT01206413 RESULTS: The home-based exercise group showed a significantly greater reduction in weight and body mass index at six months, but no difference between groups was observed thereafter. With regard to the inflammatory markers, a greater but non-statistically significant reduction was found for C-reactive protein in the home-based exercise group at six months; however, this difference disappeared after adjusting for weight change. No differences in adiponectin were found at the 6- or 12-month follow-up. Small-volume, home-based exercise did not promote changes in inflammatory markers independent of weight change.

  18. Creep of ice: further studies

    International Nuclear Information System (INIS)

    Heard, H.C.; Durham, W.B.; Kirby, S.H.

    1987-01-01

    Detailed studies have been done of ice creep as related to the icy satellites, Ganymede and Callisto. Included were: (1) the flow of high-pressure water ices II, III, and V, and (2) frictional sliding of ice I sub h. Work was also begun on the study of the effects of impurities on the flow of ice. Test results are summarized

  19. POPULASI BAKTERI PADA RUMPUT LAUT (Eucheuma Cottonii YANG TERSERANG PENYAKIT ICE-ICE

    Directory of Open Access Journals (Sweden)

    S Supatno

    2010-10-01

    Full Text Available The period of sea-weed growing under low condition is a problem that is generally faced by the farmers. The spreading of ice ice disease is affected by the environment changes that suppress the sea-weed growing and become the cause of organic substances releasing, MUCUS on thallus and also stimulate the presence of bacteria around the plantation area. The aim of this research is to know the population of bacteria on E. cottonii infected by ice-ice disease at different location. The method used in the measurement of the population bacteria is total fiat analysis (TFA. Data collection was done three times weekly on three different places Lobuk village, Bluto sub district, Sumenep. The result of observation shows that the average of bacteria population on those three different locations and also different time-observing are significantly different. The total average of bacteria populations ranges from 7278 to 18060 coloni/gr. The high value of this population is assumed as a part of the environment parameter that supports the growing of E. cottonii such as temperature and velocity.Keywords : Bacteria population, Ice-ice, E. cottonli

  20. Vortex ice in nanostructured superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Reichhardt, Charles [Los Alamos National Laboratory; Reichhardt, Cynthia J [Los Alamos National Laboratory; Libal, Andras J [Los Alamos National Laboratory

    2008-01-01

    We demonstrate using numerical simulations of nanostructured superconductors that it is possible to realize vortex ice states that are analogous to square and kagome ice. The system can be brought into a state that obeys either global or local ice rules by applying an external current according to an annealing protocol. We explore the breakdown of the ice rules due to disorder in the nanostructure array and show that in square ice, topological defects appear along grain boundaries, while in kagome ice, individual defects appear. We argue that the vortex system offers significant advantages over other artificial ice systems.

  1. Production and Evaluation of Ice Cream from Nigerian Tiger-Nut ...

    African Journals Online (AJOL)

    Ice cream was prepared from water-soluble extracts of the yellow variety of Nigerian tiger-nut. A modified standard method was used for the production of the tiger-nut milk ice cream. The resulting ice cream had pH of 7.10, 35% Brix, specific gravity of 1.0888 and total solids of 45.67%. The proximate composition of the ice ...

  2. Large sea ice outflow into the Nares Strait in 2007

    DEFF Research Database (Denmark)

    Kwok, R.; Pedersen, L.T.; Gudmandsen, Preben

    2010-01-01

    Sea ice flux through the Nares Strait is most active during the fall and early winter, ceases in mid- to late winter after the formation of ice arches along the strait, and re-commences after breakup in summer. In 2007, ice arches failed to form. This resulted in the highest outflow of Arctic sea...... at Fram Strait. Clearly, the ice arches control Arctic sea ice outflow. The duration of unobstructed flow explains more than 84% of the variance in the annual area flux. In our record, seasonal stoppages are always associated with the formation of an arch near the same location in the southern Kane Basin...... ice in the 13-year record between 1997 and 2009. The 2007 area and volume outflows of 87 x 10(3) km(2) and 254 km(3) are more than twice their 13-year means. This contributes to the recent loss of the thick, multiyear Arctic sea ice and represents similar to 10% of our estimates of the mean ice export...

  3. Ice Engineering Research Area

    Data.gov (United States)

    Federal Laboratory Consortium — Refrigerated Physical Modeling of Waterways in a Controlled EnvironmentThe Research Area in the Ice Engineering Facility at the Cold Regions Research and Engineering...

  4. Ice Cream Stick Math.

    Science.gov (United States)

    Paddock, Cynthia

    1992-01-01

    Described is a teaching technique which uses the collection of ice cream sticks as a means of increasing awareness of quantity in a self-contained elementary special class for students with learning disabilities and mild mental retardation. (DB)

  5. Global ice sheet modeling

    International Nuclear Information System (INIS)

    Hughes, T.J.; Fastook, J.L.

    1994-05-01

    The University of Maine conducted this study for Pacific Northwest Laboratory (PNL) as part of a global climate modeling task for site characterization of the potential nuclear waste respository site at Yucca Mountain, NV. The purpose of the study was to develop a global ice sheet dynamics model that will forecast the three-dimensional configuration of global ice sheets for specific climate change scenarios. The objective of the third (final) year of the work was to produce ice sheet data for glaciation scenarios covering the next 100,000 years. This was accomplished using both the map-plane and flowband solutions of our time-dependent, finite-element gridpoint model. The theory and equations used to develop the ice sheet models are presented. Three future scenarios were simulated by the model and results are discussed

  6. The Antartic Ice Borehole Probe

    Science.gov (United States)

    Behar, A.; Carsey, F.; Lane, A.; Engelhardt, H.

    2000-01-01

    The Antartic Ice Borehole Probe mission is a glaciological investigation, scheduled for November 2000-2001, that will place a probe in a hot-water drilled hole in the West Antartic ice sheet. The objectives of the probe are to observe ice-bed interactions with a downward looking camera, and ice inclusions and structure, including hypothesized ice accretion, with a side-looking camera.

  7. Ice Lens Formation, Frost Heave, Thin Films, and the Importance of the Polar H2O Reservoir at High Obliquity

    Science.gov (United States)

    Zent, A. P.; Sizemore, H. G.; Rempel, A. W.

    2011-01-01

    Several lines of evidence indicate that the volume of shallow ground ice in the martian high latitudes exceeds the pore volume of the host regolith. Boynton et al. found an optimal fit to the Mars Odyssey Gamma Ray Spectrometer (GRS) data at the Phoenix landing site by modeling a buried layer of 50-75% ice by mass (up to 90% ice by volume). Thermal and optical observations of recent impact craters in the northern hemisphere have revealed nearly pure ice. Ice deposits containing only 1-2% soil by volume were excavaged by Phoenix. One hypothesis for the origin of this excess ice is that it developed in situ by a mechanism analogous to the formation of terrestrial ice lenses and needle ice. Problematically, terrestrial soil-ice segregation is driven by freeze/thaw cycling and the movement of bulk water, neither of which are expected to have occurred in the geologically recent past on Mars. If however ice lens formation is possible at temperatures less than 273 K, there are possible implications for the habitability of Mars permafrost, since the same thin films of unfrozen water that lead to ice segregation are used by terrestrial psychrophiles to metaboluze and grow down to temperatures of at least 258 K.

  8. Totally James

    Science.gov (United States)

    Owens, Tom

    2006-01-01

    This article presents an interview with James Howe, author of "The Misfits" and "Totally Joe". In this interview, Howe discusses tolerance, diversity and the parallels between his own life and his literature. Howe's four books in addition to "The Misfits" and "Totally Joe" and his list of recommended books with lesbian, gay, bisexual, transgender,…

  9. Radiative Transfer Modeling to Estimate the Impact of CDOM on Light Absorption within Changing Arctic Sea Ice

    Science.gov (United States)

    Carns, R.; Light, B.; Frey, K. E.

    2016-12-01

    First-year sea ice differs from multi-year sea ice in several ways that can influence its optical properties. It is thinner than multi-year ice, which tends to increase light transmission. Also, first-year ice retains higher brine volumes in comparison to more heavily drained multi-year ice, in isolated pockets and channels. During melt season, patterns of pond formation on first-year sea ice differ from those on multi-year ice. As first-year sea ice comprises an increasingly large fraction of Arctic sea ice, it becomes more important to understand how much sunlight reaches the ecosystems within the ice, and how those changing ecosystems can feed back into the transmission of light. Colored dissolved organic matter (CDOM) and chlorophyll within the ice can absorb light, heating the ice and reducing transmission to the ocean below. Light also encourages algal growth within the ice while degrading CDOM, creating complex feedbacks. We use radiative transfer models to determine the overall effect of colored dissolved organic matter on the light regime within sea ice, both on the overall amount of energy transmitted and on the spectral distribution of energy. Using models allows us to estimate the impact of varying CDOM levels on a wide range of sea ice types, improving our ability to respond to conditions in a rapidly changing Arctic and predict important phenomena such as algal blooms.

  10. Total Removals Reporting

    Data.gov (United States)

    Department of Homeland Security — Data used to report on ICE statistics are obtained through the ICE Integrated Decision Support (IIDS) system data warehouse. The records in this system are refreshed...

  11. High pressure ices are not the end of the story for large icy moons habitability: experimental studies of salts effects on high pressure ices and the implications for icy worlds large hydrosphere structure and chemical evolution

    Science.gov (United States)

    Journaux, Baptiste; Abramson, Evan; Brown, J. Michael; Bollengier, Olivier

    2017-10-01

    planetary evolution scenarios implied by these new material and thermodynamic properties and how this could suggest the existence of new habitable environments in large icy worlds, even when high pressure ices dominate the total volume of the hydrosphere.

  12. Ice recrystallization inhibition in ice cream by propylene glycol monostearate.

    Science.gov (United States)

    Aleong, J M; Frochot, S; Goff, H D

    2008-11-01

    The effectiveness of propylene glycol monostearate (PGMS) to inhibit ice recrystallization was evaluated in ice cream and frozen sucrose solutions. PGMS (0.3%) dramatically reduced ice crystal sizes in ice cream and in sucrose solutions frozen in a scraped-surface freezer before and after heat shock, but had no effect in quiescently frozen solutions. PGMS showed limited emulsifier properties by promoting smaller fat globule size distributions and enhanced partial coalescence in the mix and ice cream, respectively, but at a much lower level compared to conventional ice cream emulsifier. Low temperature scanning electron microscopy revealed highly irregular crystal morphology in both ice cream and sucrose solutions frozen in a scraped-surface freezer. There was strong evidence to suggest that PGMS directly interacts with ice crystals and interferes with normal surface propagation. Shear during freezing may be required for its distribution around the ice and sufficient surface coverage.

  13. Method for maintenance of ice beds of ice condenser containment

    International Nuclear Information System (INIS)

    Scrabis, C.M.; Hardin, R.T. Jr.

    1987-01-01

    This patent describes a method of maintaining ice baskets associated with a nuclear reactor system and disposed in an array of plural such ice baskets, supported in generally vertically oriented and parallel relationship by a lattice support structure which extends between the individual ice baskets and includes lateral supports adjacent the tops of the comprising: selecting an ice basket of the array requiring replenishment of the ice therewithin due to sublimation voids within the ice charges in the basket; isolating the selected ice basket; drilling a hole downwardly through the ice charges in the ice basket in general parallel axial relationship with respect to the cylindrical sidewall of the ice basket, utilizing a rotary drill bit connected through an auger to a rotary drive means; maintaining the rotary drive means in a fixed axial position and reversing the direction of rotation thereof for driving the auger in reverse rotation; and supplying ice in particulate form to the vicinity of the auger and conveying the particulate ice through the drilled hole by continued, reverse rotation of the auger so as to fill the sublimated voids in communication with the drilled hole, from the lowest and through successively higher such voids in the ice charges within the ice basket, and withdrawing the auger from the drilled hole as the voids are filled

  14. Observations of brine plumes below melting Arctic sea ice

    Directory of Open Access Journals (Sweden)

    A. K. Peterson

    2018-02-01

    Full Text Available In sea ice, interconnected pockets and channels of brine are surrounded by fresh ice. Over time, brine is lost by gravity drainage and flushing. The timing of salt release and its interaction with the underlying water can impact subsequent sea ice melt. Turbulence measurements 1 m below melting sea ice north of Svalbard reveal anticorrelated heat and salt fluxes. From the observations, 131 salty plumes descending from the warm sea ice are identified, confirming previous observations from a Svalbard fjord. The plumes are likely triggered by oceanic heat through bottom melt. Calculated over a composite plume, oceanic heat and salt fluxes during the plumes account for 6 and 9 % of the total fluxes, respectively, while only lasting in total 0.5 % of the time. The observed salt flux accumulates to 7.6 kg m−2, indicating nearly full desalination of the ice. Bulk salinity reduction between two nearby ice cores agrees with accumulated salt fluxes to within a factor of 2. The increasing fraction of younger, more saline ice in the Arctic suggests an increase in desalination processes with the transition to the new Arctic.

  15. Observations of brine plumes below melting Arctic sea ice

    Science.gov (United States)

    Peterson, Algot K.

    2018-02-01

    In sea ice, interconnected pockets and channels of brine are surrounded by fresh ice. Over time, brine is lost by gravity drainage and flushing. The timing of salt release and its interaction with the underlying water can impact subsequent sea ice melt. Turbulence measurements 1 m below melting sea ice north of Svalbard reveal anticorrelated heat and salt fluxes. From the observations, 131 salty plumes descending from the warm sea ice are identified, confirming previous observations from a Svalbard fjord. The plumes are likely triggered by oceanic heat through bottom melt. Calculated over a composite plume, oceanic heat and salt fluxes during the plumes account for 6 and 9 % of the total fluxes, respectively, while only lasting in total 0.5 % of the time. The observed salt flux accumulates to 7.6 kg m-2, indicating nearly full desalination of the ice. Bulk salinity reduction between two nearby ice cores agrees with accumulated salt fluxes to within a factor of 2. The increasing fraction of younger, more saline ice in the Arctic suggests an increase in desalination processes with the transition to the new Arctic.

  16. Brief Communication: Mapping river ice using drones and structure from motion

    Science.gov (United States)

    Alfredsen, Knut; Haas, Christian; Tuhtan, Jeffrey A.; Zinke, Peggy

    2018-02-01

    In cold climate regions, the formation and break-up of river ice is important for river morphology, winter water supply, and riparian and instream ecology as well as for hydraulic engineering. Data on river ice is therefore significant, both to understand river ice processes directly and to assess ice effects on other systems. Ice measurement is complicated due to difficult site access, the inherent complexity of ice formations, and the potential danger involved in carrying out on-ice measurements. Remote sensing methods are therefore highly useful, and data from satellite-based sensors and, increasingly, aerial and terrestrial imagery are currently applied. Access to low cost drone systems with quality cameras and structure from motion software opens up a new possibility for mapping complex ice formations. Through this method, a georeferenced surface model can be built and data on ice thickness, spatial distribution, and volume can be extracted without accessing the ice, and with considerably fewer measurement efforts compared to traditional surveying methods. A methodology applied to ice mapping is outlined here, and examples are shown of how to successfully derive quantitative data on ice processes.

  17. Constraints on Lobate Debris Apron Evolution and Rheology from Numerical Modeling of Ice Flow

    Science.gov (United States)

    Parsons, R.; Nimmo, F.

    2010-12-01

    Recent radar observations of mid-latitude lobate debris aprons (LDAs) have confirmed the presence of ice within these deposits. Radar observations in Deuteronilus Mensae have constrained the concentration of dust found within the ice deposits to <30% by volume based on the strength of the returned signal. In addition to constraining the dust fraction, these radar observations can measure the ice thickness - providing an opportunity to more accurately estimate the flow behavior of ice responsible for the formation of LDAs. In order to further constrain the age and rheology of LDA ice, we developed a numerical model simulating ice flow under Martian conditions using results from ice deformation experiments, theory of ice grain growth based on terrestrial ice cores, and observational constraints from radar profiles and laser altimetry. This finite difference model calculates the LDA profile shape as it flows over time assuming no basal slip. In our model, the ice rheology is determined by the concentration of dust which influences the ice grain size by pinning the ice grain boundaries and halting ice grain growth. By varying the dust fraction (and therefore the ice grain size), the ice temperature, the subsurface slope, and the initial ice volume we are able to determine the combination of parameters that best reproduce the observed LDA lengths and thicknesses over a period of time comparable to crater age dates of LDA surfaces (90 - 300 My, see figure). Based on simulations using different combinations of ice temperature, ice grain size, and basal slope, we find that an ice temperature of 205 K, a dust volume fraction of 0.5% (resulting in an ice grain size of 5 mm), and a flat subsurface slope give reasonable model LDA ages for many LDAs in the northern mid-latitudes of Mars. However, we find that there is no single combination of dust fraction, temperature, and subsurface slope which can give realistic ages for all LDAs suggesting that all or some of these

  18. Linking Regional Winter Sea Ice Thickness and Surface Roughness to Spring Melt Pond Fraction on Landfast Arctic Sea Ice

    Directory of Open Access Journals (Sweden)

    Sasha Nasonova

    2017-12-01

    Full Text Available The Arctic sea ice cover has decreased strongly in extent, thickness, volume and age in recent decades. The melt season presents a significant challenge for sea ice forecasting due to uncertainty associated with the role of surface melt ponds in ice decay at regional scales. This study quantifies the relationships of spring melt pond fraction (fp with both winter sea ice roughness and thickness, for landfast first-year sea ice (FYI and multiyear sea ice (MYI. In 2015, airborne measurements of winter sea ice thickness and roughness, as well as high-resolution optical data of melt pond covered sea ice, were collected along two ~5.2 km long profiles over FYI- and MYI-dominated regions in the Canadian Arctic. Statistics of winter sea ice thickness and roughness were compared to spring fp using three data aggregation approaches, termed object and hybrid-object (based on image segments, and regularly spaced grid-cells. The hybrid-based aggregation approach showed strongest associations because it considers the morphology of the ice as well as footprints of the sensors used to measure winter sea ice thickness and roughness. Using the hybrid-based data aggregation approach it was found that winter sea ice thickness and roughness are related to spring fp. A stronger negative correlation was observed between FYI thickness and fp (Spearman rs = −0.85 compared to FYI roughness and fp (rs = −0.52. The association between MYI thickness and fp was also negative (rs = −0.56, whereas there was no association between MYI roughness and fp. 47% of spring fp variation for FYI and MYI can be explained by mean thickness. Thin sea ice is characterized by low surface roughness allowing for widespread ponding in the spring (high fp whereas thick sea ice has undergone dynamic thickening and roughening with topographic features constraining melt water into deeper channels (low fp. This work provides an important contribution towards the parameterizations of fp in

  19. The Antarctic Ice Sheet, Sea Ice, and the Ozone Hole: Satellite Observations of how they are Changing

    Science.gov (United States)

    Parkinson, Claire L.

    2012-01-01

    Antarctica is the Earth's coldest and highest continent and has major impacts on the climate and life of the south polar vicinity. It is covered almost entirely by the Earth's largest ice sheet by far, with a volume of ice so great that if all the Antarctic ice were to go into the ocean (as ice or liquid water), this would produce a global sea level rise of about 60 meters (197 feet). The continent is surrounded by sea ice that in the wintertime is even more expansive than the continent itself and in the summertime reduces to only about a sixth of its wintertime extent. Like the continent, the expansive sea ice cover has major impacts, reflecting the sun's radiation back to space, blocking exchanges between the ocean and the atmosphere, and providing a platform for some animal species while impeding other species. Far above the continent, the Antarctic ozone hole is a major atmospheric phenomenon recognized as human-caused and potentially quite serious to many different life forms. Satellites are providing us with remarkable information about the ice sheet, the sea ice, and the ozone hole. Satellite visible and radar imagery are providing views of the large scale structure of the ice sheet never seen before; satellite laser altimetry has produced detailed maps of the topography of the ice sheet; and an innovative gravity-measuring two-part satellite has allowed mapping of regions of mass loss and mass gain on the ice sheet. The surrounding sea ice cover has a satellite record that goes back to the 1970s, allowing trend studies that show a decreasing sea ice presence in the region of the Bellingshausen and Amundsen seas, to the west of the prominent Antarctic Peninsula, but increasing sea ice presence around much of the rest of the continent. Overall, sea ice extent around Antarctica has increased at an average rate of about 17,000 square kilometers per year since the late 1970s, as determined from satellite microwave data that can be collected under both light and

  20. Measurement of the atmospheric muon neutrino energy spectrum with IceCube in the 79- and 86-String configuration

    Directory of Open Access Journals (Sweden)

    Ruhe T.

    2016-01-01

    Full Text Available IceCube is a neutrino telescope with an instrumented volume of one cubic kilometer. A total of 5160 Digital Optical Modules (DOMs is deployed on 86 strings forming a three dimensional detector array. Although primarily designed for the detection of neutrinos from astrophysical sources, the detector can be used for spectral measurements of atmospheric neutrinos. These spectral measurements are hindered by a dominant background of atmospheric muons. State-of-the-art techniques from Machine Learning and Data Mining are required to select a high-purity sample of atmospheric neutrino candidates. The energy spectrum of muon neutrinos is obtained from energy-dependent input variables by utilizing regularized unfolding. The results obtained using IceCube in the 79- and 86-string configuration are presented in this paper.

  1. Reconstruction of the Greenland ice sheet dynamics in a fully coupled Earth System Model

    Science.gov (United States)

    Rybak, Oleg; Volodin, Evgeny; Huybrechts, Philippe

    2016-04-01

    Earth system models (ESMs) are undoubtedly effective tools for studying climate dynamics. Incorporation of evolving ice sheets to ESMs is a challenging task because response times of the climate system and of ice sheets differ by several orders of magnitude. Besides, AO GCMs operate on spatial and temporal resolutions substantially differing from those of ice sheet models (ICMs). Therefore elaboration of an effective coupling methodology of an AO GCM and an ICM is the key problem of an ESM construction and utilization. Several downscaling strategies of varying complexity exist now of data exchange between modeled climate system and ice sheets. Application of a particular strategy depends on the research objectives. In our view, the optimum approach for model studying of significant environmental changes (e.g. glacial/interglacial transitions) when ice sheets undergo substantial evolution of geometry and volume would be an asynchronous coupling. The latter allows simulation in the interactive way of growth and decay of ice sheets in the changing climatic conditions. In the focus of the presentation, is the overview of coupling aspects of an AO GCM INMCM32 elaborated in the Institute of Numerical Mathematics (Moscow, Russia) to the Greenland ice sheet model (GrISM, Vrije Uninersiteit Brussel, Belgium). To provide interactive coupling of INMCM32 (spatial resolution 5°×4°, 21 vertical layers and temporal resolution 6 min. in the atmospheric block) and GrISM (spatial resolution 20×20 km, 51 vertical layers and 1 yr temporal resolution), we employ a special energy- and water balance model (EWBM-G), which serves as a buffer providing effective data exchange between INMCM32 and GrISM. EWBM-G operates in a rectangle domain including Greenland. Transfer of daily meanings of simulated climatic variables (air surface temperature and specific humidity) is provided on the lateral boundarias of the domain and inside the domain (sea level air pressure, wind speed and total

  2. Aerodynamics and thermal physics of helicopter ice accretion

    Science.gov (United States)

    Han, Yiqiang

    developed based on a set of 82 experimental measurements and also compared to existing predictions tools. Two reference predictions found in the literature yielded 76% and 54% discrepancy with respect to experimental testing, whereas the proposed ice roughness prediction model resulted in a 31% minimum accuracy in prediction. It must be noted that the accuracy of the proposed model is within the ice shape reproduction uncertainty of icing facilities. Based on the new ice roughness prediction model and the CSR heat transfer scaling method, an icing heat transfer model was developed. The approach achieved high accuracy in heat transfer prediction compared to experiments conducted at the AERTS facility. The discrepancy between predictions and experimental results was within +/-15%, which was within the measurement uncertainty range of the facility. By combining both the ice roughness and heat transfer predictions, and incorporating the modules into an existing ice prediction tool (LEWICE), improved prediction capability was obtained, especially for the glaze regime. With the available ice shapes accreted at the AERTS facility and additional experiments found in the literature, 490 sets of experimental ice shapes and corresponding aerodynamics testing data were available. A physics-based performance degradation empirical tool was developed and achieved a mean absolute deviation of 33% when compared to the entire experimental dataset, whereas 60% to 243% discrepancies were observed using legacy drag penalty prediction tools. Rotor torque predictions coupling Blade Element Momentum Theory and the proposed drag performance degradation tool was conducted on a total of 17 validation cases. The coupled prediction tool achieved a 10% predicting error for clean rotor conditions, and 16% error for iced rotor conditions. It was shown that additional roughness element could affect the measured drag by up to 25% during experimental testing, emphasizing the need of realistic ice structures

  3. Ice flow Modelling of the Greenland Ice Sheet

    DEFF Research Database (Denmark)

    Nielsen, Lisbeth Tangaa

    Models of ice flow have a range of application in glaciology, including investigating the large-scale response of ice sheets to changes in climate, assimilating data to estimate unknown conditions beneath the ice sheet, and in interpreting proxy records obtained from ice cores, among others. In t...... a steady state with respect to the reference climate at the end of the simulation and that the mass balance of the ice sheet at this time was more sensitive to recent climate fluctuations than the temperature forcing in the early or mid-Holocene.......Models of ice flow have a range of application in glaciology, including investigating the large-scale response of ice sheets to changes in climate, assimilating data to estimate unknown conditions beneath the ice sheet, and in interpreting proxy records obtained from ice cores, among others....... In this PhD project, the use of ice flow models for the interpretation of the age-structure of the Greenland ice sheet, i.e. the depth within the ice, at which ice deposited at given times are found at present day. Two different observational data sets of this archive were investigated. Further, paleo...

  4. Modeling Commercial Turbofan Engine Icing Risk With Ice Crystal Ingestion

    Science.gov (United States)

    Jorgenson, Philip C. E.; Veres, Joseph P.

    2013-01-01

    The occurrence of ice accretion within commercial high bypass aircraft turbine engines has been reported under certain atmospheric conditions. Engine anomalies have taken place at high altitudes that have been attributed to ice crystal ingestion, partially melting, and ice accretion on the compression system components. The result was degraded engine performance, and one or more of the following: loss of thrust control (roll back), compressor surge or stall, and flameout of the combustor. As ice crystals are ingested into the fan and low pressure compression system, the increase in air temperature causes a portion of the ice crystals to melt. It is hypothesized that this allows the ice-water mixture to cover the metal surfaces of the compressor stationary components which leads to ice accretion through evaporative cooling. Ice accretion causes a blockage which subsequently results in the deterioration in performance of the compressor and engine. The focus of this research is to apply an engine icing computational tool to simulate the flow through a turbofan engine and assess the risk of ice accretion. The tool is comprised of an engine system thermodynamic cycle code, a compressor flow analysis code, and an ice particle melt code that has the capability of determining the rate of sublimation, melting, and evaporation through the compressor flow path, without modeling the actual ice accretion. A commercial turbofan engine which has previously experienced icing events during operation in a high altitude ice crystal environment has been tested in the Propulsion Systems Laboratory (PSL) altitude test facility at NASA Glenn Research Center. The PSL has the capability to produce a continuous ice cloud which are ingested by the engine during operation over a range of altitude conditions. The PSL test results confirmed that there was ice accretion in the engine due to ice crystal ingestion, at the same simulated altitude operating conditions as experienced previously in

  5. Estimation of Antarctic Land-Fast Sea Ice Algal Biomass and Snow Thickness From Under-Ice Radiance Spectra in Two Contrasting Areas

    Science.gov (United States)

    Wongpan, P.; Meiners, K. M.; Langhorne, P. J.; Heil, P.; Smith, I. J.; Leonard, G. H.; Massom, R. A.; Clementson, L. A.; Haskell, T. G.

    2018-03-01

    Fast ice is an important component of Antarctic coastal marine ecosystems, providing a prolific habitat for ice algal communities. This work examines the relationships between normalized difference indices (NDI) calculated from under-ice radiance measurements and sea ice algal biomass and snow thickness for Antarctic fast ice. While this technique has been calibrated to assess biomass in Arctic fast ice and pack ice, as well as Antarctic pack ice, relationships are currently lacking for Antarctic fast ice characterized by bottom ice algae communities with high algal biomass. We analyze measurements along transects at two contrasting Antarctic fast ice sites in terms of platelet ice presence: near and distant from an ice shelf, i.e., in McMurdo Sound and off Davis Station, respectively. Snow and ice thickness, and ice salinity and temperature measurements support our paired in situ optical and biological measurements. Analyses show that NDI wavelength pairs near the first chlorophyll a (chl a) absorption peak (≈440 nm) explain up to 70% of the total variability in algal biomass. Eighty-eight percent of snow thickness variability is explained using an NDI with a wavelength pair of 648 and 567 nm. Accounting for pigment packaging effects by including the ratio of chl a-specific absorption coefficients improved the NDI-based algal biomass estimation only slightly. Our new observation-based algorithms can be used to estimate Antarctic fast ice algal biomass and snow thickness noninvasively, for example, by using moored sensors (time series) or mapping their spatial distributions using underwater vehicles.

  6. The impact of the Ice Model on tau neutrino reconstruction in IceCube

    Energy Technology Data Exchange (ETDEWEB)

    Usner, Marcel; Kowalski, Marek [DESY Zeuthen (Germany); Collaboration: IceCube-Collaboration

    2015-07-01

    The IceCube Neutrino Observatory at the South Pole is a Cherenkov detector with an instrumented volume of about one cubic kilometer of the Antarctic ice. Tau neutrinos can be measured via the double bang signature that links two subsequent cascades from the neutrino interaction and the tau decay. Reconstruction of double bang events is currently limited to PeV energies and above where the decay length of the tau is greater than 50 m. At lower energies it is important to consider small effects that affect the propagation of Cherenkov photons in the ice. The most recent model of the glacial ice below South pole contains a tilt of the ice layers and an anisotropy of the scattering coefficient in the direction of the glacier flow. These effects cannot be incorporated trivially into the existing reconstruction methods and can have a significant impact on single and double cascade reconstruction. Updates on finding a solution to this problem are presented, and the effect on the reconstruction of tau neutrino events is discussed.

  7. Loss of sea ice during winter north of Svalbard

    Directory of Open Access Journals (Sweden)

    Ingrid H. Onarheim

    2014-06-01

    Full Text Available Sea ice loss in the Arctic Ocean has up to now been strongest during summer. In contrast, the sea ice concentration north of Svalbard has experienced a larger decline during winter since 1979. The trend in winter ice area loss is close to 10% per decade, and concurrent with a 0.3°C per decade warming of the Atlantic Water entering the Arctic Ocean in this region. Simultaneously, there has been a 2°C per decade warming of winter mean surface air temperature north of Svalbard, which is 20–45% higher than observations on the west coast. Generally, the ice edge north of Svalbard has retreated towards the northeast, along the Atlantic Water pathway. By making reasonable assumptions about the Atlantic Water volume and associated heat transport, we show that the extra oceanic heat brought into the region is likely to have caused the sea ice loss. The reduced sea ice cover leads to more oceanic heat transferred to the atmosphere, suggesting that part of the atmospheric warming is driven by larger open water area. In contrast to significant trends in sea ice concentration, Atlantic Water temperature and air temperature, there is no significant temporal trend in the local winds. Thus, winds have not caused the long-term warming or sea ice loss. However, the dominant winds transport sea ice from the Arctic Ocean into the region north of Svalbard, and the local wind has influence on the year-to-year variability of the ice concentration, which correlates with surface air temperatures, ocean temperatures, as well as the local wind.

  8. The ICES system

    International Nuclear Information System (INIS)

    Inzaghi, A.

    1983-01-01

    ICES is an integrated system used in the various engineering fields. It is made up of the Basic System and the applied Subsystems. ICES is controlled by the Operating System of the computer, from which it calls for suitable services: space allocation, loading of the modules etc... To be able to use software of this type on a computer the Operating System should be made more general. The Subsystems are developed with special programs included in the ICES Basic System. Each Subsystem is associated with an area of application. In other words, a Subsystem can only treat a previously defined ''class of problems''. The engineer (user) communicates with the Subsystem using a language oriented towards the problem (POL) also previously defined using the CDL language. The use of the (POL) language makes the engineer-computer contact much easier. The applied programs written in ICETRAN, once supplied as input to the ICETRAN Precompiler, become Fortran programs with special characteristics. A Fortran compiler produces the corresponding object programs with which, using the ICES ''Link-edit'' procedures, one obtains the modules which can be executed by an ICES Subsystem

  9. The response of the southern Greenland ice sheet to the Holocene thermal maximum

    DEFF Research Database (Denmark)

    Larsen, Nicolaj Krog; Kjaer, Kurt H.; Lecavalier, Benoit

    2015-01-01

    contribution of 0.16 m sea-level equivalent from the entire Greenland ice sheet, with a centennial ice loss rate of as much as 100 Gt/yr for several millennia during the Holocene thermal maximum. Our results provide an estimate of the long-term rates of volume loss that can be expected in the future...

  10. Future climate warming increases Greenland ice sheet surface mass balance variability

    NARCIS (Netherlands)

    Fyke, J.G.; Vizcaino, M.; Lipscomb, W.; Price, S.

    2014-01-01

    The integrated surface mass balance (SMB) of the Greenland ice sheet (GrIS) has large interannual variability. Long-term future changes to this variability will affect GrIS dynamics, freshwater fluxes, regional oceanography, and detection of changes in ice volume trends. Here we analyze a simulated

  11. Ice Engineering. Number 25, September 2000. Remote Ice Motion Detection

    National Research Council Canada - National Science Library

    2000-01-01

    .... Government agencies, and the engineering community in general. The potential exists for property damage, serious injury, and fatalities during ice-related flooding, evacuations, and other ice mitigation operations...

  12. Association of Habitual Patterns and Types of Physical Activity and Inactivity with MRI-Determined Total Volumes of Visceral and Subcutaneous Abdominal Adipose Tissue in a General White Population.

    Directory of Open Access Journals (Sweden)

    Karina Fischer

    Full Text Available Population-based evidence for the role of habitual physical activity (PA in the accumulation of visceral (VAT and subcutaneous (SAAT abdominal adipose tissue is limited. We investigated if usual patterns and types of self-reported PA and inactivity were associated with VAT and SAAT in a general white population. Total volumes of VAT and SAAT were quantified by magnetic resonance imaging in 583 men and women (61 ± 11.9 y; BMI 27.2 ± 4.4 kg/m2. Past-year PA and inactivity were self-reported by questionnaire. Exploratory activity patterns (APAT were derived by principal components analysis. Cross-sectional associations between individual activities, total PA in terms of metabolic equivalents (PA MET, or overall APAT and either VAT or SAAT were analyzed by multivariable-adjusted robust or generalized linear regression models. Whereas vigorous-intensity PA (VPA was negatively associated with both VAT and SAAT, associations between total PA MET, moderate-intensity PA (MPA, or inactivity and VAT and/or SAAT depended on sex. There was also evidence of a threshold effect in some of these relationships. Total PA MET was more strongly associated with VAT in men (B = -3.3 ± 1.4; P = 0.02 than women (B = -2.1 ± 1.1; P = 0.07, but was more strongly associated with SAAT in women (B = -5.7 ± 2.5; P = 0.05 than men (B = -1.7 ± 1.6; P = 0.3. Men (-1.52 dm3 or -1.89 dm3 and women (-1.15 dm3 or -2.61 dm3 in the highest (>6.8 h/wk VPA or second (4.0-6.8 h/wk VPA tertile of an APAT rich in VPA, had lower VAT and SAAT, respectively, than those in the lowest (<4.0 h/wk VPA tertile (P ≤ 0.016; P trend ≤ 0.0005. They also had lower VAT and SAAT than those with APAT rich in MPA and/or inactivity only. In conclusion, our results suggest that in white populations, habitual APAT rich in MPA might be insufficient to impact on accumulation of VAT or SAAT. APAT including ≥ 4.0-6.8 h/wk VPA, by contrast, are more strongly associated with lower VAT and SAAT.

  13. Blood volume studies

    International Nuclear Information System (INIS)

    Lewis, S.M.; Yin, J.A.L.

    1986-01-01

    The use of dilution analysis with such radioisotopes as 51 Cr, 32 P, sup(99m)Tc and sup(113m)In for measuring red cell volume is reviewed briefly. The use of 125 I and 131 I for plasma volume studies is also considered and the subsequent determination of total blood volume discussed, together with the role of the splenic red cell volume. Substantial bibliography. (UK)

  14. Supraglacial bacterial community structures vary across the Greenland ice sheet

    DEFF Research Database (Denmark)

    Cameron, Karen A.; Stibal, Marek; Zarsky, Jakub D.

    2016-01-01

    The composition and spatial variability of microbial communities that reside within the extensive (>200 000 km(2)) biologically active area encompassing the Greenland ice sheet (GrIS) is hypothesized to be variable. We examined bacterial communities from cryoconite debris and surface ice across...... the GrIS, using sequence analysis and quantitative PCR of 16S rRNA genes from co-extracted DNA and RNA. Communities were found to differ across the ice sheet, with 82.8% of the total calculated variation attributed to spatial distribution on a scale of tens of kilometers separation. Amplicons related...... to Sphingobacteriaceae, Pseudanabaenaceae and WPS-2 accounted for the greatest portion of calculated dissimilarities. The bacterial communities of ice and cryoconite were moderately similar (global R = 0.360, P = 0.002) and the sampled surface type (ice versus cryoconite) did not contribute heavily towards community...

  15. Tradition and Technology: Sea Ice Science on Inuit Sleds

    Science.gov (United States)

    Wilkinson, Jeremy P.; Hanson, Susanne; Hughes, Nick E.; James, Alistair; Jones, Bryn; MacKinnon, Rory; Rysgaard, Søren; Toudal, Leif

    2011-01-01

    The Arctic is home to a circumpolar community of native people whose culture and traditions have enabled them to thrive in what most would perceive as a totally inhospitable and untenable environment. In many ways, sea ice can be viewed as the glue that binds these northern communities together; it is utilized in all aspects of their daily life. Sea ice acts as highways of the north; indeed, one can travel on these highways with dogsleds and snowmobiles. These travels over the frozen ocean occur at all periods of the sea ice cycle and over different ice types and ages. Excursions may be hunting trips to remote regions or social visits to nearby villages. Furthermore, hunting on the sea ice contributes to the health, culture, and commercial income of a community.

  16. Modeling the evolution of the Laurentide Ice Sheet from MIS 3 to the Last Glacial Maximum: an approach using sea level modeling and ice flow dynamics

    Science.gov (United States)

    Weisenberg, J.; Pico, T.; Birch, L.; Mitrovica, J. X.

    2017-12-01

    The history of the Laurentide Ice Sheet since the Last Glacial Maximum ( 26 ka; LGM) is constrained by geological evidence of ice margin retreat in addition to relative sea-level (RSL) records in both the near and far field. Nonetheless, few observations exist constraining the ice sheet's extent across the glacial build-up phase preceding the LGM. Recent work correcting RSL records along the U.S. mid-Atlantic dated to mid-MIS 3 (50-35 ka) for glacial-isostatic adjustment (GIA) infer that the Laurentide Ice Sheet grew by more than three-fold in the 15 ky leading into the LGM. Here we test the plausibility of a late and extremely rapid glaciation by driving a high-resolution ice sheet model, based on a nonlinear diffusion equation for the ice thickness. We initialize this model at 44 ka with the mid-MIS 3 ice sheet configuration proposed by Pico et al. (2017), GIA-corrected basal topography, and mass balance representative of mid-MIS 3 conditions. These simulations predict rapid growth of the eastern Laurentide Ice Sheet, with rates consistent with achieving LGM ice volumes within 15 ky. We use these simulations to refine the initial ice configuration and present an improved and higher resolution model for North American ice cover during mid-MIS 3. In addition we show that assumptions of ice loads during the glacial phase, and the associated reconstructions of GIA-corrected basal topography, produce a bias that can underpredict ice growth rates in the late stages of the glaciation, which has important consequences for our understanding of the speed limit for ice growth on glacial timescales.

  17. Rheology of planetary ices

    Energy Technology Data Exchange (ETDEWEB)

    Durham, W.B. [Lawrence Livermore National Lab., CA (United States); Kirby, S.H.; Stern, L.A. [Geological Survey, Menlo Park, CA (United States)

    1996-04-24

    The brittle and ductile rheology of ices of water, ammonia, methane, and other volatiles, in combination with rock particles and each other, have a primary influence of the evolution and ongoing tectonics of icy moons of the outer solar system. Laboratory experiments help constrain the rheology of solar system ices. Standard experimental techniques can be used because the physical conditions under which most solar system ices exist are within reach of conventional rock mechanics testing machines, adapted to the low subsolidus temperatures of the materials in question. The purpose of this review is to summarize the results of a decade-long experimental deformation program and to provide some background in deformation physics in order to lend some appreciation to the application of these measurements to the planetary setting.

  18. Ice accreditation vs wind

    Energy Technology Data Exchange (ETDEWEB)

    Sabourin, G. [Hydro-Quebec, PQ (Canada). TransEnergie Div.; Chouinard, L. [McGill Univ., Montreal, PQ (Canada); Feknous, N. [SNC-Lavalin, Montreal, PQ (Canada)

    2002-07-01

    Wind and ice data from Hydro Quebec and Environment Canada indicates that winds during ice storms are in the general direction of the St. Lawrence River. This observation is important for upgrading existing power transmission lines from the Manicouagan and Churchill generation system because they are parallel to the St. Lawrence and they were designed with lower criteria than is currently accepted. ASCE 74 suggests an accumulation ratio based on thickness of 0.70 for winds parallel to the line. The Goodwin model was used to calculate this ratio. The presentation includes illustrations showing the accumulation ratio for a north wind, as well as the accumulation ratios and wind roses at Quebec. A table showing a comparison of ratios from passive ice meters shows that results are similar to mean values from the theoretical model.

  19. Detecting high spatial variability of ice shelf basal mass balance, Roi Baudouin Ice Shelf, Antarctica

    Directory of Open Access Journals (Sweden)

    S. Berger

    2017-11-01

    Full Text Available Ice shelves control the dynamic mass loss of ice sheets through buttressing and their integrity depends on the spatial variability of their basal mass balance (BMB, i.e. the difference between refreezing and melting. Here, we present an improved technique – based on satellite observations – to capture the small-scale variability in the BMB of ice shelves. As a case study, we apply the methodology to the Roi Baudouin Ice Shelf, Dronning Maud Land, East Antarctica, and derive its yearly averaged BMB at 10 m horizontal gridding. We use mass conservation in a Lagrangian framework based on high-resolution surface velocities, atmospheric-model surface mass balance and hydrostatic ice-thickness fields (derived from TanDEM-X surface elevation. Spatial derivatives are implemented using the total-variation differentiation, which preserves abrupt changes in flow velocities and their spatial gradients. Such changes may reflect a dynamic response to localized basal melting and should be included in the mass budget. Our BMB field exhibits much spatial detail and ranges from −14.7 to 8.6 m a−1 ice equivalent. Highest melt rates are found close to the grounding line where the pressure melting point is high, and the ice shelf slope is steep. The BMB field agrees well with on-site measurements from phase-sensitive radar, although independent radar profiling indicates unresolved spatial variations in firn density. We show that an elliptical surface depression (10 m deep and with an extent of 0.7 km × 1.3 km lowers by 0.5 to 1.4 m a−1, which we tentatively attribute to a transient adaptation to hydrostatic equilibrium. We find evidence for elevated melting beneath ice shelf channels (with melting being concentrated on the channel's flanks. However, farther downstream from the grounding line, the majority of ice shelf channels advect passively (i.e. no melting nor refreezing toward the ice shelf front. Although the absolute, satellite

  20. Mapping Ross Ice Shelf with ROSETTA-Ice airborne laser altimetry

    Science.gov (United States)

    Becker, M. K.; Fricker, H. A.; Padman, L.; Bell, R. E.; Siegfried, M. R.; Dieck, C. C. M.

    2017-12-01

    The Ross Ocean and ice Shelf Environment and Tectonic setting Through Aerogeophysical surveys and modeling (ROSETTA-Ice) project combines airborne glaciological, geological, and oceanographic observations to enhance our understanding of the history and dynamics of the large ( 500,000 square km) Ross Ice Shelf (RIS). Here, we focus on the Light Detection And Ranging (LiDAR) data collected in 2015 and 2016. This data set represents a significant advance in resolution: Whereas the last attempt to systematically map RIS (the surface-based RIGGS program in the 1970s) was at 55 km grid spacing, the ROSETTA-Ice grid has 10-20 km line spacing and much higher along-track resolution. We discuss two different strategies for processing the raw LiDAR data: one that requires proprietary software (Riegl's RiPROCESS package), and one that employs open-source programs and libraries. With the processed elevation data, we are able to resolve fine-scale ice-shelf features such as the "rampart-moat" ice-front morphology, which has previously been observed on and modeled for icebergs. This feature is also visible in the ROSETTA-Ice shallow-ice radar data; comparing the laser data with radargrams provides insight into the processes leading to their formation. Near-surface firn state and total firn air content can also be investigated through combined analysis of laser altimetry and radar data. By performing similar analyses with data from the radar altimeter aboard CryoSat-2, we demonstrate the utility of the ROSETTA-Ice LiDAR data set in satellite validation efforts. The incorporation of the LiDAR data from the third and final field season (December 2017) will allow us to construct a DEM and an ice thickness map of RIS for the austral summers of 2015-2017. These products will be used to validate and extend observations of height changes from satellite radar and laser altimetry, as well as to update regional models of ocean circulation and ice dynamics.

  1. Numerical flow simulation over clean and iced wind turbine blades

    Energy Technology Data Exchange (ETDEWEB)

    Villalpando, F.; Reggio, M. [Ecole Polytechnique, Montreal, PQ (Canada); Ilinca, A. [Quebec Univ., Rimouski, PQ (Canada). Wind Energy Group

    2009-07-01

    The impact of ice accretion on the drag and lift coefficients of a wind turbine blade was studied. Computerized simulations were conducted for both clean and ice-accreted 2-D airfoils at various angles of attack. The finite volume-based commercial computational fluid dynamics (CFD) program FLUENT was used to simulate the 2-D geometries of turbulent, unsteady and incompressible flow around the airfoils. Pressure coefficients and the contribution of pressure and friction forces to the lift and drag coefficients were analyzed. The study showed that traditional calculations over-predict the lift and drag of ice-accreted airfoil profiles. Ice accreted over the profile's pressure side provoked a bigger lift reduction and drag increase than that caused by ice accreted on the suction side. The poor performance of the aerodynamic coefficients was attributed to the contribution of pressure forces. Further experimentation is required to determine if de-icing systems for turbine blades should be developed to prevent or melt ice over the profile pressure side. 11 refs., 7 tabs., 15 figs.

  2. Physiological, physical and on-ice performance criteria for selection of elite ice hockey teams

    Directory of Open Access Journals (Sweden)

    R Roczniok

    2016-01-01

    Full Text Available The purpose of this study was to examine physiological and physical determinants of ice-hockey performance in order to assess their impact on the result during a selection for ice hockey. A total of 42 ice hockey players took part in the selection camp. At the end of the camp 20 best players were selected by team of expert coaches to the ice hockey team and created group G1, while the second group (G2 consisted of not selected players (non-successful group Evaluation of goodness of fit of the model to the data was based on the Hosmer Lemeshow test Ice hockey players selected to the team were taller 181.95±4.02 cm, had lower % body fat 13.17±3.17%, a shorter time to peak power 2.47±0.35 s , higher relative peak power 21.34±2.41 W • kg-1 and higher relative total work 305.18±28.41 J • kg-1. The results of the aerobic capacity test showed significant differences only in case of two variables. Ice hockey players in the G1 had higher VO2max 4.07±0.31 l • min-1 values than players in the G2 as well as ice hockey players in G1 showed a higher level of relative VO2max 51.75±2.99 ml • min-1 • kg-1 than athletes in G2. Ice hockey players selected to the team (G1 performed better in the 30 m Forwards Sprint 4.28±0.31 s; 6x9 Turns 12.19±0.75 s; 6x9 stops 12.79±0.49 s and Endurance test (6x30 m stops 32.01±0.80 s than players in G2. The logistic regression model showed that the best predictors of success in the recruitment process of top level ice hockey players were time to peak power, relative peak power, VO2max and 30 m sprint forwards on ice. On the basis of the constructed predictive logistic regression model it will be possible to determine the probability of success of the athletes during following the selection processes to the team.

  3. Patterned basal seismicity shows sub-ice stream bedforms

    Science.gov (United States)

    Barcheck, C. G.; Tulaczyk, S. M.; Schwartz, S. Y.

    2017-12-01

    Patterns in seismicity emanating from the bottom of fast-moving ice streams and glaciers may indicate localized patches of higher basal resistance— sometimes called 'sticky spots', or otherwise varying basal properties. These seismogenic basal areas resist an unknown portion of the total driving stress of the Whillans Ice Plain (WIP), in West Antarctica, but may play an important role in the WIP stick-slip cycle and ice stream slowdown. To better understand the mechanism and importance of basal seismicity beneath the WIP, we analyze seismic data collected by a small aperture (micro-earthquakes in Dec 2014, and we compare the resulting map of seismicity to ice bottom depth measured by airborne radar. The number of basal earthquakes per area within the network is spatially heterogeneous, but a pattern of two 400m wide streaks of high seismicity rates is evident, with >50-500 earthquakes detected per 50x50m grid cell in 2 weeks. These seismically active streaks are elongated approximately in the ice flow direction with a spacing of 750m. Independent airborne radar measurements of ice bottom depth from Jan 2013 show a low-amplitude ( 5m) undulation in the basal topography superposed on a regional gradient in ice bottom depth. The flow-perpendicular wavelength of these low-amplitude undulations is comparable to the spacing of the high seismicity bands, and the streaks of high seismicity intersect local lows in the undulating basal topography. We interpret these seismic and radar observations as showing seismically active sub-ice stream bedforms that are low amplitude and elongated in the direction of ice flow, comparable to the morphology of mega scale glacial lineations (MSGLs), with high basal seismicity rates observed in the MSGL troughs. These results have implications for understanding the formation mechanism of MSGLS and well as understanding the interplay between basal topographic roughness, spatially varying basal till and hydrologic properties, basal

  4. High-density amorphous ice: A path-integral simulation

    Science.gov (United States)

    Herrero, Carlos P.; Ramírez, Rafael

    2012-09-01

    Structural and thermodynamic properties of high-density amorphous (HDA) ice have been studied by path-integral molecular dynamics simulations in the isothermal-isobaric ensemble. Interatomic interactions were modeled by using the effective q-TIP4P/F potential for flexible water. Quantum nuclear motion is found to affect several observable properties of the amorphous solid. At low temperature (T = 50 K) the molar volume of HDA ice is found to increase by 6%, and the intramolecular O-H distance rises by 1.4% due to quantum motion. Peaks in the radial distribution function of HDA ice are broadened with respect to their classical expectancy. The bulk modulus, B, is found to rise linearly with the pressure, with a slope ∂B/∂P = 7.1. Our results are compared with those derived earlier from classical and path-integral simulations of HDA ice. We discuss similarities and discrepancies with those earlier simulations.

  5. Trace analysis of organic ions in ice samples by capillary electrophoresis

    Energy Technology Data Exchange (ETDEWEB)

    Huber, T. [Bern Univ. (Switzerland); Schwikowski, M.; Gaeggeler, H.W. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-09-01

    Capillary electrophoresis was tested as a new analytical method for ice samples. Comparisons to ion chromatography were made concerning accuracy, detection limits, reproducibility, necessary sample volume and time consumption. (author) 1 fig., 3 refs.

  6. Trace analysis of organic ions in ice samples by capillary electrophoresis

    International Nuclear Information System (INIS)

    Huber, T.; Schwikowski, M.; Gaeggeler, H.W.

    1997-01-01

    Capillary electrophoresis was tested as a new analytical method for ice samples. Comparisons to ion chromatography were made concerning accuracy, detection limits, reproducibility, necessary sample volume and time consumption. (author) 1 fig., 3 refs

  7. Ice cores and palaeoclimate

    International Nuclear Information System (INIS)

    Krogh Andersen, K.; Ditlevsen, P.; Steffensen, J.P.

    2001-01-01

    Ice cores from Greenland give testimony of a highly variable climate during the last glacial period. Dramatic climate warmings of 15 to 25 deg. C for the annual average temperature in less than a human lifetime have been documented. Several questions arise: Why is the Holocene so stable? Is climatic instability only a property of glacial periods? What is the mechanism behind the sudden climate changes? Are the increased temperatures in the past century man-made? And what happens in the future? The ice core community tries to attack some of these problems. The NGRIP ice core currently being drilled is analysed in very high detail, allowing for a very precise dating of climate events. It will be possible to study some of the fast changes on a year by year basis and from this we expect to find clues to the sequence of events during rapid changes. New techniques are hoped to allow for detection of annual layers as far back as 100,000 years and thus a much improved time scale over past climate changes. It is also hoped to find ice from the Eemian period. If the Eemian layers confirm the GRIP sequence, the Eemian was actually climatically unstable just as the glacial period. This would mean that the stability of the Holocene is unique. It would also mean, that if human made global warming indeed occurs, we could jeopardize the Holocene stability and create an unstable 'Eemian situation' which ultimately could start an ice age. Currenlty mankind is changing the composition of the atmosphere. Ice cores document significant increases in greenhouse gases, and due to increased emissions of sulfuric and nitric acid from fossil fuel burning, combustion engines and agriculture, modern Greenland snow is 3 - 5 times more acidic than pre-industrial snow (Mayewski et al., 1986). However, the magnitude and abruptness of the temperature changes of the past century do not exceed the magnitude of natural variability. It is from the ice core perspective thus not possible to attribute the

  8. ICE Online Detainee Locator System

    Data.gov (United States)

    Department of Homeland Security — The Online Detainee Locator datasets provide the location of a detainee who is currently in ICE custody, or who was release from ICE custody for any reason with the...

  9. International Conference on Environment Science (ICES 2012)

    CERN Document Server

    Advances in Computational Environment Science

    2012-01-01

    2012 International Conference on Environment Science and 2012 International Conference on Computer Science (ICES 2012/ICCS 2012) will be held in Australia, Melbourne, 15‐16 March, 2012.Volume 1 contains some new results in computational environment science. There are 47 papers were selected as the regular paper in this volume. It contains the latest developments and reflects the experience of many researchers working in different environments (universities, research centers or even industries), publishing new theories and solving new technological problems on computational environment science.   The purpose of volume 1 is interconnection of diverse scientific fields, the cultivation of every possible scientific collaboration, the exchange of views and the promotion of new research targets as well as the further dissemination, the dispersion, the diffusion of the environment science, including but not limited to Ecology, Physics, Chemistry, Biology, Soil Science, Geology, Atmospheric Science and Geography �...

  10. Configurational entropy of hydrogen-disordered ice polymorphs

    International Nuclear Information System (INIS)

    Herrero, Carlos P.; Ramírez, Rafael

    2014-01-01

    The configurational entropy of several H-disordered ice polymorphs is calculated by means of a thermodynamic integration along a path between a totally H-disordered state and one fulfilling the Bernal-Fowler ice rules. A Monte Carlo procedure based on a simple energy model is used, so that the employed thermodynamic path drives the system from high temperatures to the low-temperature limit. This method turns out to be precise enough to give reliable values for the configurational entropy s th of different ice phases in the thermodynamic limit (number of molecules N → ∞). The precision of the method is checked for the ice model on a two-dimensional square lattice. Results for the configurational entropy are given for H-disordered arrangements on several polymorphs, including ices Ih, Ic, II, III, IV, V, VI, and XII. The highest and lowest entropy values correspond to ices VI and XII, respectively, with a difference of 3.3% between them. The dependence of the entropy on the ice structures has been rationalized by comparing it with structural parameters of the various polymorphs, such as the mean ring size. A particularly good correlation has been found between the configurational entropy and the connective constant derived from self-avoiding walks on the ice networks

  11. Quantifying the ice-albedo feedback through decoupling

    Science.gov (United States)

    Kravitz, B.; Rasch, P. J.

    2017-12-01

    The ice-albedo feedback involves numerous individual components, whereby warming induces sea ice melt, inducing reduced surface albedo, inducing increased surface shortwave absorption, causing further warming. Here we attempt to quantify the sea ice albedo feedback using an analogue of the "partial radiative perturbation" method, but where the governing mechanisms are directly decoupled in a climate model. As an example, we can isolate the insulating effects of sea ice on surface energy and moisture fluxes by allowing sea ice thickness to change but fixing Arctic surface albedo, or vice versa. Here we present results from such idealized simulations using the Community Earth System Model in which individual components are successively fixed, effectively decoupling the ice-albedo feedback loop. We isolate the different components of this feedback, including temperature change, sea ice extent/thickness, and air-sea exchange of heat and moisture. We explore the interactions between these different components, as well as the strengths of the total feedback in the decoupled feedback loop, to quantify contributions from individual pieces. We also quantify the non-additivity of the effects of the components as a means of investigating the dominant sources of nonlinearity in the ice-albedo feedback.

  12. Interannual observations and quantification of summertime H2O ice deposition on the Martian CO2 ice south polar cap

    Science.gov (United States)

    Brown, Adrian J.; Piqueux, Sylvain; Titus, Timothy N.

    2014-01-01

    The spectral signature of water ice was observed on Martian south polar cap in 2004 by the Observatoire pour l'Mineralogie, l'Eau les Glaces et l'Activite (OMEGA) ( Bibring et al., 2004). Three years later, the OMEGA instrument was used to discover water ice deposited during southern summer on the polar cap ( Langevin et al., 2007). However, temporal and spatial variations of these water ice signatures have remained unexplored, and the origins of these water deposits remains an important scientific question. To investigate this question, we have used observations from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) instrument on the Mars Reconnaissance Orbiter (MRO) spacecraft of the southern cap during austral summer over four Martian years to search for variations in the amount of water ice. We report below that for each year we have observed the cap, the magnitude of the H2O ice signature on the southern cap has risen steadily throughout summer, particularly on the west end of the cap. The spatial extent of deposition is in disagreement with the current best simulations of deposition of water ice on the south polar cap (Montmessin et al., 2007). This increase in water ice signatures is most likely caused by deposition of atmospheric H2O ice and a set of unusual conditions makes the quantification of this transport flux using CRISM close to ideal. We calculate a ‘minimum apparent‘ amount of deposition corresponding to a thin H2O ice layer of 0.2 mm (with 70% porosity). This amount of H2O ice deposition is 0.6–6% of the total Martian atmospheric water budget. We compare our ‘minimum apparent’ quantification with previous estimates. This deposition process may also have implications for the formation and stability of the southern CO2 ice cap, and therefore play a significant role in the climate budget of modern day Mars.

  13. Can You Depend Totally on Computers?

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 3; Issue 2. Can You Depend Totally on Computers? Computer Security, Availability and Correctness. H N Mahabala. General Article Volume 3 Issue 2 February 1998 pp 35-44 ...

  14. The IceProd Framework

    DEFF Research Database (Denmark)

    Aartsen, M.G.; Abbasi, R.; Ackermann, M.

    2015-01-01

    of computational resources. IceProd is a distributed management system based on Python, XML-RPC and GridFTP. It is driven by a central database in order to coordinate and admin- ister production of simulations and processing of data produced by the IceCube detector. IceProd runs as a separate layer on top of other...

  15. 2006 Program of Study: Ice

    Science.gov (United States)

    2007-03-01

    form a debris flow. One such debris flow, initiated by a glacial lake flood in Peru in 1941, devastated the city of Huaraz, killing over 6000 people [5...ice, a series of’ prototype interlocking fingers is formed which grow ats the ice floes areI compressed and the ice floes plough through one another

  16. Polar Ice Caps: a Canary for the Greenland Ice Sheet

    Science.gov (United States)

    Honsaker, W.; Lowell, T. V.; Sagredo, E.; Kelly, M. A.; Hall, B. L.

    2010-12-01

    Ice caps are glacier masses that are highly sensitive to climate change. Because of their hypsometry they can have a binary state. When relatively slight changes in the equilibrium line altitude (ELA) either intersect or rise above the land the ice can become established or disappear. Thus these upland ice masses have a fast response time. Here we consider a way to extract the ELA signal from independent ice caps adjacent to the Greenland Ice Sheet margin. It may be that these ice caps are sensitive trackers of climate change that also impact the ice sheet margin. One example is the Istorvet Ice Cap located in Liverpool Land, East Greenland (70.881°N, 22.156°W). The ice cap topography and the underlying bedrock surface dips to the north, with peak elevation of the current ice ranging in elevation from 1050 to 745 m.a.s.l. On the eastern side of the ice mass the outlet glaciers extending down to sea level. The western margin has several small lobes in topographic depressions, with the margin reaching down to 300 m.a.s.l. Topographic highs separate the ice cap into at least 5 main catchments, each having a pair of outlet lobes toward either side of the ice cap. Because of the regional bedrock slope each catchment has its own elevation range. Therefore, as the ELA changes it is possible for some catchments of the ice cap to experience positive mass balance while others have a negative balance. Based on weather observations we estimate the present day ELA to be ~1000 m.a.s.l, meaning mass balance is negative for the majority of the ice cap. By tracking glacier presence/absence in these different catchments, we can reconstruct small changes in the ELA. Another example is the High Ice Cap (informal name) in Milne Land (70.903°N, 25.626°W, 1080 m), East Greenland. Here at least 4 unconformities in ice layers found near the southern margin of the ice cap record changing intervals of accumulation and ablation. Therefore, this location may also be sensitive to slight

  17. Perturbation and melting of snow and ice by the 13 November 1985 eruption of Nevado del Ruiz, Colombia, and consequent mobilization, flow and deposition of lahars

    Science.gov (United States)

    Pierson, T.C.; Janda, R.J.; Thouret, J.-C.; Borrero, C.A.

    1990-01-01

    A complex sequence of pyroclastic flows and surges erupted by Nevado del Ruiz volcano on 13 November 1985 interacted with snow and ice on the summit ice cap to trigger catastrophic lahars (volcanic debris flows), which killed more than 23,000 people living at or beyond the base of the volcano. The rapid transfer of heat from the hot eruptive products to about 10 km2 of the snowpack, combined with seismic shaking, produced large volumes of meltwater that flowed downslope, liquefied some of the new volcanic deposits, and generated avalanches of saturated snow, ice and rock debris within minutes of the 21:08 (local time) eruption. About 2 ?? 107 m3 of water was discharged into the upper reaches of the Molinos, Nereidas, Guali, Azufrado and Lagunillas valleys, where rapid entrainment of valley-fill sediment transformed the dilute flows and avalanches to debris flows. Computed mean velocities of the lahars at peak flow ranged up to 17 m s-1. Flows were rapid in the steep, narrow upper canyons and slowed with distance away from the volcano as flow depth and channel slope diminished. Computed peak discharges ranged up to 48,000 m3 s-1 and were greatest in reaches 10 to 20 km downstream from the summit. A total of about 9 ?? 107 m3 of lahar slurry was transported to depositional areas up to 104 km from the source area. Initial volumes of individual lahars increased up to 4 times with distance away from the summit. The sedimentology and stratigraphy of the lahar deposits provide compelling evidence that: (1) multiple initial meltwater pulses tended to coalesce into single flood waves; (2) lahars remained fully developed debris flows until they reached confluences with major rivers; and (3) debris-flow slurry composition and rheology varied to produce gradationally density-stratified flows. Key lessons and reminders from the 1985 Nevado del Ruiz volcanic eruption are: (1) catastrophic lahars can be generated on ice- and snow-capped volcanoes by relatively small eruptions; (2

  18. Dynamic Antarctic ice sheet during the early to mid-Miocene

    Science.gov (United States)

    Gasson, Edward; DeConto, Robert M.; Pollard, David; Levy, Richard H.

    2016-03-01

    Geological data indicate that there were major variations in Antarctic ice sheet volume and extent during the early to mid-Miocene. Simulating such large-scale changes is problematic because of a strong hysteresis effect, which results in stability once the ice sheets have reached continental size. A relatively narrow range of atmospheric CO2 concentrations indicated by proxy records exacerbates this problem. Here, we are able to simulate large-scale variability of the early to mid-Miocene Antarctic ice sheet because of three developments in our modeling approach. (i) We use a climate-ice sheet coupling method utilizing a high-resolution atmospheric component to account for ice sheet-climate feedbacks. (ii) The ice sheet model includes recently proposed mechanisms for retreat into deep subglacial basins caused by ice-cliff failure and ice-shelf hydrofracture. (iii) We account for changes in the oxygen isotopic composition of the ice sheet by using isotope-enabled climate and ice sheet models. We compare our modeling results with ice-proximal records emerging from a sedimentological drill core from the Ross Sea (Andrill-2A) that is presented in a companion article. The variability in Antarctic ice volume that we simulate is equivalent to a seawater oxygen isotope signal of 0.52-0.66‰, or a sea level equivalent change of 30-36 m, for a range of atmospheric CO2 between 280 and 500 ppm and a changing astronomical configuration. This result represents a substantial advance in resolving the long-standing model data conflict of Miocene Antarctic ice sheet and sea level variability.

  19. Polar Stereographic Valid Ice Masks Derived from National Ice Center Monthly Sea Ice Climatologies, Version 1

    Data.gov (United States)

    National Aeronautics and Space Administration — These valid ice masks provide a way to remove spurious ice caused by residual weather effects and land spillover in passive microwave data. They are derived from the...

  20. User's guide for ICE

    International Nuclear Information System (INIS)

    Fraley, S.K.

    1976-07-01

    ICE is a cross-section mixing code which will accept cross sections from an AMPX working library and produce mixed cross sections in the AMPX working library format, ANISN format, and the group-independent ANISN format. User input is in the free-form or fixed-form FIDO structure. The code is operable as a module in the AMPX system

  1. Autosub under ice

    OpenAIRE

    Griffiths, G.

    2005-01-01

    Autosub made headlines recently when it became trapped under 200m of ice in Antarctica.Here we explore the ideas behind the £5.86 million research programme, and look back at an earlier expedition which took place last summer off the coast of Greenland.

  2. Melting ice, growing trade?

    Directory of Open Access Journals (Sweden)

    Sami Bensassi

    2016-05-01

    Full Text Available Abstract Large reductions in Arctic sea ice, most notably in summer, coupled with growing interest in Arctic shipping and resource exploitation have renewed interest in the economic potential of the Northern Sea Route (NSR. Two key constraints on the future viability of the NSR pertain to bathymetry and the future evolution of the sea ice cover. Climate model projections of future sea ice conditions throughout the rest of the century suggest that even under the most “aggressive” emission scenario, increases in international trade between Europe and Asia will be very low. The large inter-annual variability of weather and sea ice conditions in the route, the Russian toll imposed for transiting the NSR, together with high insurance costs and scarce loading/unloading opportunities, limit the use of the NSR. We show that even if these obstacles are removed, the duration of the opening of the NSR over the course of the century is not long enough to offer a consequent boost to international trade at the macroeconomic level.

  3. Ecology under lake ice

    NARCIS (Netherlands)

    Hampton, Stephanie E.; Galloway, Aaron W. E.; Powers, Stephen M.; Ozersky, Ted; Woo, Kara H.; Batt, Ryan D.; Labou, Stephanie G.; O'Reilly, Catherine M.; Sharma, Sapna; Lottig, Noah R.; Stanley, Emily H.; North, Rebecca L.; Stockwell, Jason D.; Adrian, Rita; Weyhenmeyer, Gesa A.; Arvola, Lauri; Baulch, Helen M.; Bertani, Isabella; Bowman, Larry L., Jr.; Carey, Cayelan C.; Catalan, Jordi; Colom-Montero, William; Domine, Leah M.; Felip, Marisol; Granados, Ignacio; Gries, Corinna; Grossart, Hans-Peter; Haberman, Juta; Haldna, Marina; Hayden, Brian; Higgins, Scott N.; Jolley, Jeff C.; Kahilainen, Kimmo K.; Kaup, Enn; Kehoe, Michael J.; MacIntyre, Sally; Mackay, Anson W.; Mariash, Heather L.; Mckay, Robert M.; Nixdorf, Brigitte; Noges, Peeter; Noges, Tiina; Palmer, Michelle; Pierson, Don C.; Post, David M.; Pruett, Matthew J.; Rautio, Milla; Read, Jordan S.; Roberts, Sarah L.; Ruecker, Jacqueline; Sadro, Steven; Silow, Eugene A.; Smith, Derek E.; Sterner, Robert W.; Swann, George E. A.; Timofeyev, Maxim A.; Toro, Manuel; Twiss, Michael R.; Vogt, Richard J.; Watson, Susan B.; Whiteford, Erika J.; Xenopoulos, Marguerite A.

    Winter conditions are rapidly changing in temperate ecosystems, particularly for those that experi-ence periods of snow and ice cover. Relatively little is known of winter ecology in these systems,due to a historical research focus on summer ‘growing seasons’. We executed the first global

  4. Relationship between Physiological Off-Ice Testing, On-Ice Skating, and Game Performance in Division I Women's Ice Hockey Players.

    Science.gov (United States)

    Boland, Michelle; Miele, Emily M; Delude, Katie

    2017-10-07

    The purpose was to identify off-ice testing variables that correlate to skating and game performance in Division I collegiate women ice hockey players. Twenty female, forward and defensive players (19.95 ± 1.35 yr) were assessed for weight, height, percent fat mass (%FAT), bone mineral density, predicted one repetition maximum (RM) absolute and relative (REL%) bench press (BP) and hex bar deadlift (HDL), lower body explosive power, anaerobic power, countermovement vertical jump (CMJ), maximum inspiratory pressure (MIP), and on-ice repeated skate sprint (RSS) performance. The on-ice RSS test included 6 timed 85.6 m sprints with participants wearing full hockey equipment; fastest time (FT), average time (AT) and fatigue index (FI) for the first length skate (FLS; 10 m) and total length skate (TLS; 85.6 m) were used for analysis. Game performance was evaluated with game statistics: goals, assists, points, plus-minus, and shots on goal (SOG). Correlation coefficients were used to determine relationships. Percent fat mass was positively correlated (p Game performance in women ice hockey players may be enhanced by greater MIP, repeat acceleration ability, and mode-specific training. Faster skating times were associated with lower %FAT. Skating performance in women ice hockey players may be enhanced by improving body composition, anaerobic power, and both lower and upper body strength in off-ice training.

  5. Ice shelf fracture parameterization in an ice sheet model

    Directory of Open Access Journals (Sweden)

    S. Sun

    2017-11-01

    Full Text Available Floating ice shelves exert a stabilizing force onto the inland ice sheet. However, this buttressing effect is diminished by the fracture process, which on large scales effectively softens the ice, accelerating its flow, increasing calving, and potentially leading to ice shelf breakup. We add a continuum damage model (CDM to the BISICLES ice sheet model, which is intended to model the localized opening of crevasses under stress, the transport of those crevasses through the ice sheet, and the coupling between crevasse depth and the ice flow field and to carry out idealized numerical experiments examining the broad impact on large-scale ice sheet and shelf dynamics. In each case we see a complex pattern of damage evolve over time, with an eventual loss of buttressing approximately equivalent to halving the thickness of the ice shelf. We find that it is possible to achieve a similar ice flow pattern using a simple rule of thumb: introducing an enhancement factor ∼ 10 everywhere in the model domain. However, spatially varying damage (or equivalently, enhancement factor fields set at the start of prognostic calculations to match velocity observations, as is widely done in ice sheet simulations, ought to evolve in time, or grounding line retreat can be slowed by an order of magnitude.

  6. Ice shelf fracture parameterization in an ice sheet model

    Science.gov (United States)

    Sun, Sainan; Cornford, Stephen L.; Moore, John C.; Gladstone, Rupert; Zhao, Liyun

    2017-11-01

    Floating ice shelves exert a stabilizing force onto the inland ice sheet. However, this buttressing effect is diminished by the fracture process, which on large scales effectively softens the ice, accelerating its flow, increasing calving, and potentially leading to ice shelf breakup. We add a continuum damage model (CDM) to the BISICLES ice sheet model, which is intended to model the localized opening of crevasses under stress, the transport of those crevasses through the ice sheet, and the coupling between crevasse depth and the ice flow field and to carry out idealized numerical experiments examining the broad impact on large-scale ice sheet and shelf dynamics. In each case we see a complex pattern of damage evolve over time, with an eventual loss of buttressing approximately equivalent to halving the thickness of the ice shelf. We find that it is possible to achieve a similar ice flow pattern using a simple rule of thumb: introducing an enhancement factor ˜ 10 everywhere in the model domain. However, spatially varying damage (or equivalently, enhancement factor) fields set at the start of prognostic calculations to match velocity observations, as is widely done in ice sheet simulations, ought to evolve in time, or grounding line retreat can be slowed by an order of magnitude.

  7. Autonomous Ice Mass Balance Buoys for Seasonal Sea Ice

    Science.gov (United States)

    Whitlock, J. D.; Planck, C.; Perovich, D. K.; Parno, J. T.; Elder, B. C.; Richter-Menge, J.; Polashenski, C. M.

    2017-12-01

    The ice mass-balance represents the integration of all surface and ocean heat fluxes and attributing the impact of these forcing fluxes on the ice cover can be accomplished by increasing temporal and spatial measurements. Mass balance information can be used to understand the ongoing changes in the Arctic sea ice cover and to improve predictions of future ice conditions. Thinner seasonal ice in the Arctic necessitates the deployment of Autonomous Ice Mass Balance buoys (IMB's) capable of long-term, in situ data collection in both ice and open ocean. Seasonal IMB's (SIMB's) are free floating IMB's that allow data collection in thick ice, thin ice, during times of transition, and even open water. The newest generation of SIMB aims to increase the number of reliable IMB's in the Arctic by leveraging inexpensive commercial-grade instrumentation when combined with specially developed monitoring hardware. Monitoring tasks are handled by a custom, expandable data logger that provides low-cost flexibility for integrating a large range of instrumentation. The SIMB features ultrasonic sensors for direct measurement of both snow depth and ice thickness and a digital temperature chain (DTC) for temperature measurements every 2cm through both snow and ice. Air temperature and pressure, along with GPS data complete the Arctic picture. Additionally, the new SIMB is more compact to maximize deployment opportunities from multiple types of platforms.

  8. Emplacement of Antarctic ice sheet mass affects circumpolar ocean flow

    NARCIS (Netherlands)

    Rugenstein, Maria; Stocchi, Paolo; von der Heydt, Anna; Dijkstra, Hendrik; Brinkhuis, Henk

    2014-01-01

    During the Cenozoic the Antarctic continent experienced large fluctuations in ice-sheet volume. We investigate the effects of Glacial Isostatic Adjustment (GIA) on Southern Ocean circulation for the first continental scale glaciation of Antarctica (~34 Myr) by combining solid Earth and ocean dynamic

  9. Emplacement of Antarctic ice sheet mass affects circumpolar ocean flow

    NARCIS (Netherlands)

    Rugenstein, M.; Stocchi, P.; van der Heydt, A.; Brinkhuis, H.

    2014-01-01

    During the Cenozoic the Antarctic continent experienced large fluctuations in ice-sheet volume. We investigate the effects of Glacial Isostatic Adjustment (GIA) on Southern Ocean circulation for the first continental scale glaciation of Antarctica (~ 34 Myr) by combining solid Earth and ocean

  10. Sea ice contribution to the air-sea CO(2) exchange in the Arctic and Southern Oceans

    DEFF Research Database (Denmark)

    Rysgaard...[], Søren; Bendtsen, Jørgen; Delille, B.

    2011-01-01

    Although salt rejection from sea ice is a key process in deep-water formation in ice-covered seas, the concurrent rejection of CO(2) and the subsequent effect on air-sea CO(2) exchange have received little attention. We review the mechanisms by which sea ice directly and indirectly controls the air......-sea CO(2) exchange and use recent measurements of inorganic carbon compounds in bulk sea ice to estimate that oceanic CO(2) uptake during the seasonal cycle of sea-ice growth and decay in ice-covered oceanic regions equals almost half of the net atmospheric CO(2) uptake in ice-free polar seas. This sea......-sea CO(2) exchange during winter, and (3) release of CO(2)-depleted melt water with excess total alkalinity during sea-ice decay and (4) biological CO(2) drawdown during primary production in sea ice and surface oceanic waters....

  11. Heterogeneous ice nucleation

    Energy Technology Data Exchange (ETDEWEB)

    Bogdan, A. [Helsinki Univ. (Finland). Dept. of Physics

    1994-12-31

    The classical theory of heterogenous ice nucleation is reviewed in detail. The modelling of ice nucleation in the adsorbed water films on natural particles by analogous ice nucleation in adsorbed water films on the walls of porous media is discussed. Ice nucleation in adsorbed films of purewater and the HNO{sub 3}/H{sub 2}0 binary system on the surface of porous aerosol (SiO{sub 2}) was investigated using the method of NMR spectroscopy. The median freezing temperature and freezing temperature region were shown to be highly sensitive both to the average thickness of the adsorbed films and to the amount of adsorbed nitric acid. The character of the ice phase formation tends to approach that of bulk liquid with increasing adsorbed film thickness. Under the given conditions the thickness of the adsorbed films decreases with an increasing amount of adsorbed nitric acid molecules The molar concentration of nitric acid in the adsorbed films is very small (of the order of 10{sup -}3 10{sup -}2 (M/l)). Nitric acid molecules tend to adsorb on the surface of aerosol to a greater extent than in subsequent layers. The concentration is greatest in layers situated close to the surface and sharply decreases with the distance from the surface. The difference between the median freezing temperatures for adsorbed pure water and for the binary system was found to be about 9 K for films of equal thickness. This is about 150 times greater than the difference between the median freezing temperatures of bulk pure water and a solution with the same concentration of nitric acid. (orig.)

  12. Landscape Evolution and the Reincarnation of the Residual CO2 Ice Cap of Mars

    Science.gov (United States)

    Byrne, S.; Zuber, M.

    2006-12-01

    residual CO2 ice cap. We invoke unusual depositional episodes (which have a surface smoothing effect) after which the cap can begin accumulating mass and growing in thickness again. This continues until the surface roughness again exceeds a stable state and the process repeats itself. The thickness of the residual cap therefore oscillates on timescales of centuries. The total cap volume may also be affected by variations in residual cap extent. The cap is not 'stable' in the usual sense of the word, but instead is constantly being destroyed and recreated. Evidence suggests that these rejuvenating depositional events are linked to global dust storms. The 10m thick stratigraphic record thus provides a unique measure of interannual variability of the current climate, the expanding Swiss-cheese features do not indicate secular climate change, but instead are just part of the larger life-cycle of this ice deposit. We will report on this surface modeling which reproduces other morphologies within the residual cap and present a historical model based on combining our modeling with the feature sizes and ablation rates found within the present residual ice cap.

  13. Lower Monoamine Oxidase-A Total Distribution Volume in Impulsive and Violent Male Offenders with Antisocial Personality Disorder and High Psychopathic Traits: An [(11)C] Harmine Positron Emission Tomography Study.

    Science.gov (United States)

    Kolla, Nathan J; Matthews, Brittany; Wilson, Alan A; Houle, Sylvain; Bagby, R Michael; Links, Paul; Simpson, Alexander I; Hussain, Amina; Meyer, Jeffrey H

    2015-10-01

    Antisocial personality disorder (ASPD) often presents with highly impulsive, violent behavior, and pathological changes in the orbitofrontal cortex (OFC) and ventral striatum (VS) are implicated. Several compelling reasons support a relationship between low monoamine oxidase-A (MAO-A), an enzyme that regulates neurotransmitters, and ASPD. These include MAO-A knockout models in rodents evidencing impulsive aggression and positron emission tomography (PET) studies of healthy subjects reporting associations between low brain MAO-A levels and greater impulsivity or aggression. However, a fundamental gap in the literature is that it is unknown whether brain MAO-A levels are low in more severe, clinical disorders of impulsivity, such as ASPD. To address this issue, we applied [(11)C] harmine PET to measure MAO-A total distribution volume (MAO-A VT), an index of MAO-A density, in 18 male ASPD participants and 18 age- and sex-matched controls. OFC and VS MAO-A VT were lower in ASPD compared with controls (multivariate analysis of variance (MANOVA): F2,33=6.8, P=0.003; OFC and VS MAO-A VT each lower by 19%). Similar effects were observed in other brain regions: prefrontal cortex, anterior cingulate cortex, dorsal putamen, thalamus, hippocampus, and midbrain (MANOVA: F7,28=2.7, P=0.029). In ASPD, VS MAO-A VT was consistently negatively correlated with self-report and behavioral measures of impulsivity (r=-0.50 to -0.52, all P-valuesdisorder marked by pathological aggression and impulsivity.

  14. Prognostic value of whole-body metabolic tumour volume and total lesion glycolysis measured on {sup 18}F-FDG PET/CT in patients with extranodal NK/T-cell lymphoma

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Choon-Young; Hong, Chae Moon; Kim, Do-Hoon; Son, Seung Hyun; Jeong, Shin Young; Lee, Sang-Woo; Lee, Jaetae; Ahn, Byeong-Cheol [Kyungpook National University School of Medicine and Hospital, Department of Nuclear Medicine, Daegu (Korea, Republic of)

    2013-09-15

    The aim of this study was to determine whether maximum standardized uptake value (SUVmax), whole-body metabolic tumour volume (WBMTV), and whole-body total lesion glycolysis (WBTLG) measured on pretreatment {sup 18}F-FDG PET/CT can predict prognosis in patients with extranodal natural killer/T-cell lymphoma (ENKTL). We conducted a retrospective analysis of 20 patients with newly-diagnosed ENKTL who underwent pretreatment {sup 18}F-FDG PET/CT. WBMTV and WBTLG were measured automatically using the boundaries of voxels presenting SUV > 3.0. Uni- and multivariate analyses for survival and disease progression were performed using clinical variables and PET parameters (SUVmax, WBMTV, and WBTLG). During the follow-up period (median 26.3 months), 12 patients showed disease progression and 10 patients died from the disease. Receiver operating characteristic curve analysis showed cut-off values for SUVmax, WBMTV and WBTLG of 8.1, 14.4 cm{sup 3} and 52.7, respectively. Univariate analysis showed that the International Prognostic Index (IPI) score and PET parameters were significant predictors of overall survival (OS) and progression-free survival (PFS). Multivariate analysis, even after adjustment for the IPI score, showed that high WBMTV was the best predictor of OS and PFS, and high SUVmax and WBTLG were significant predictors of PFS. Our results suggested that the use of PET parameters together with the IPI score may be useful for detailed prediction of prognosis in ENKTL patients. Therefore, despite a lower IPI score, patients with high PET parameter values might be considered candidates for aggressive therapy to improve clinical outcomes. (orig.)

  15. A data-calibrated distribution of deglacial chronologies for the North American ice complex from glaciological modeling

    Science.gov (United States)

    Tarasov, Lev; Dyke, Arthur S.; Neal, Radford M.; Peltier, W. R.

    2012-01-01

    5 meter living range for the Acropora Palmata coral. 20 ka ice volume for North America was likely 70.1 ± 2.0 m eustatic, or about 60% of the total contribution to eustatic sea level change. We suspect that the potentially most critical unquantified uncertainties in our analyses are those related to model structure (especially climate forcing), deglacial ice margin chronology, and earth rheology.

  16. Transnational Sea-Ice Transport in a Warmer, More Mobile Arctic

    Science.gov (United States)

    Newton, R.; Tremblay, B.; Pfirman, S. L.; DeRepentigny, P.

    2015-12-01

    As the Arctic sea ice thins, summer ice continues to shrink in its area, and multi-year ice becomes rarer, winter ice is not disappearing from the Arctic Basin. Rather, it is ever more dominated by first year ice. And each summer, as the total coverage withdraws, the first year ice is able travel faster and farther, carrying any ice-rafted material with it. Micro-organisms, sediments, pollutants and river runoff all move across the Arctic each summer and are deposited hundreds of kilometers from their origins. Analyzing Arctic sea ice drift patterns in the context of the exclusive economic zones (EEZs) of the Arctic nations raises concerns about the changing fate of "alien" ice which forms within one country's EEZ, then drifts and melts in another country's EEZ. We have developed a new data set from satellite-based ice-drift data that allows us to track groups of ice "pixels" forward from their origin to their destination, or backwards from their melting location to their point of formation. The software has been integrated with model output to extend the tracking of sea ice to include climate projections. Results indicate, for example, that Russian sea ice dominates "imports" to the EEZ of Norway, as expected, but with increasing ice mobility it is also is exported into the EEZs of other countries, including Canada and the United States. Regions of potential conflict are identified, including several national borders with extensive and/or changing transboundary sea ice transport. These data are a starting point for discussion of transborder questions raised by "alien" ice and the material it may import from one nation's EEZ to another's.

  17. Bibliography of Ice Properties and Forecasting Related to Transportation in Ice-Covered Waters.

    Science.gov (United States)

    1980-09-01

    N. and Tabata , T., Ice study in the Gulf of Peschanskii, I.S., Ice science and ice technology, Bothnia, III: observations on large grains of ice...ice and by Sterrett, K.F., The arctic environment and the hitting ice floes. Results of these measurements have arctic surface effect vehicle, Cold...ice growth, temperature 26-3673 effects, ice cover thickness. 28-557 Determining contact stresses when a ship’s stem hits the ice, Kheisin, D.E

  18. Greenland Regional and Ice Sheet-wide Geometry Sensitivity to Boundary and Initial conditions

    Science.gov (United States)

    Logan, L. C.; Narayanan, S. H. K.; Greve, R.; Heimbach, P.

    2017-12-01

    Ice sheet and glacier model outputs require inputs from uncertainly known initial and boundary conditions, and other parameters. Conservation and constitutive equations formalize the relationship between model inputs and outputs, and the sensitivity of model-derived quantities of interest (e.g., ice sheet volume above floatation) to model variables can be obtained via the adjoint model of an ice sheet. We show how one particular ice sheet model, SICOPOLIS (SImulation COde for POLythermal Ice Sheets), depends on these inputs through comprehensive adjoint-based sensitivity analyses. SICOPOLIS discretizes the shallow-ice and shallow-shelf approximations for ice flow, and is well-suited for paleo-studies of Greenland and Antarctica, among other computational domains. The adjoint model of SICOPOLIS was developed via algorithmic differentiation, facilitated by the source transformation tool OpenAD (developed at Argonne National Lab). While model sensitivity to various inputs can be computed by costly methods involving input perturbation simulations, the time-dependent adjoint model of SICOPOLIS delivers model sensitivities to initial and boundary conditions throughout time at lower cost. Here, we explore both the sensitivities of the Greenland Ice Sheet's entire and regional volumes to: initial ice thickness, precipitation, basal sliding, and geothermal flux over the Holocene epoch. Sensitivity studies such as described here are now accessible to the modeling community, based on the latest version of SICOPOLIS that has been adapted for OpenAD to generate correct and efficient adjoint code.

  19. Sea Ice and Hydrographic Variability in the Northwest North Atlantic

    Science.gov (United States)

    Fenty, I. G.; Heimbach, P.; Wunsch, C. I.

    2010-12-01

    Sea ice anomalies in the Northwest North Atlantic's Labrador Sea are of climatic interest because of known and hypothesized feedbacks with hydrographic anomalies, deep convection/mode water formation, and Northern Hemisphere atmospheric patterns. As greenhouse gas concentrations increase, hydrographic anomalies formed in the Arctic Ocean associated with warming will propagate into the Labrador Sea via the Fram Strait/West Greenland Current and the Canadian Archipelago/Baffin Island Current. Therefore, understanding the dynamical response of sea ice in the basin to hydrographic anomalies is essential for the prediction and interpretation of future high-latitude climate change. Historically, efforts to quantify the link between the observed sea ice and hydrographic variability in the region has been limited due to in situ observation paucity and technical challenges associated with synthesizing ocean and sea ice observations with numerical models. To elaborate the relationship between sea ice and ocean variability, we create three one-year (1992-1993, 1996-1997, 2003-2004) three-dimensional time-varying reconstructions of the ocean and sea ice state in Labrador Sea and Baffin Bay. The reconstructions are syntheses of a regional coupled 32 km ocean-sea ice model with a suite of contemporary in situ and satellite hydrographic and ice data using the adjoint method. The model and data are made consistent, in a least-squares sense, by iteratively adjusting several model control variables (e.g., ocean initial and lateral boundary conditions and the atmospheric state) to minimize an uncertainty-weighted model-data misfit cost function. The reconstructions reveal that the ice pack attains a state of quasi-equilibrium in mid-March (the annual sea ice maximum) in which the total ice-covered area reaches a steady state -ice production and dynamical divergence along the coasts balances dynamical convergence and melt along the pack’s seaward edge. Sea ice advected to the

  20. Laboratory, Computational and Theoretical Investigations of Ice Nucleation and its Implications for Mixed Phase Clouds

    Science.gov (United States)

    Yang, Fan

    Ice particles in atmospheric clouds play an important role in determining cloud lifetime, precipitation and radiation. It is therefore important to understand the whole life cycle of ice particles in the atmosphere, e.g., where they come from (nucleation), how they evolve (growth), and where they go (precipitation). Ice nucleation is the crucial step for ice formation, and in this study, we will mainly focus on ice nucleation in the lab and its effect on mixed-phase stratiform clouds. In the first half of this study, we investigate the relevance of moving contact lines (i.e., the region where three or more phases meet) on the phenomenon of contact nucleation. High speed video is used to investigate heterogeneous ice nucleation in supercooled droplets resting on cold substrates under two different dynamic conditions: droplet electrowetting and droplet vibration. The results show that contact-line motion is not a sufficient condition to trigger ice nucleation, while locally curved contact lines that can result from contact-line motion are strongly related to ice nucleation. We propose that pressure perturbations due to locally curved contact lines can strongly enhance the ice nucleation rate, which gives another interpretation for the mechanism for contact nucleation. Corresponding theoretical results provide a quantitative connection between pressure perturbations and temperature, providing a useful tool for ice nucleation calculations in atmospheric models. In this second half of the study, we build a minimalist model for long lifetime mixed-phase stratiform clouds based on stochastic ice nucleation. Our result shows that there is a non-linear relationship between ice water contact and ice number concentration in the mixed-phase cloud, as long as the volume ice nucleation rate is constant. This statistical property may help identify the source of ice nuclei in mixed-phase clouds. In addition, results from Lagrangian ice particle tracking in time dependent fields

  1. The complete mitochondrial genome of the ice pigeon (Columba livia breed ice).

    Science.gov (United States)

    Zhang, Rui-Hua; He, Wen-Xiao

    2015-02-01

    The ice pigeon is a breed of fancy pigeon developed over many years of selective breeding. In the present work, we report the complete mitochondrial genome sequence of ice pigeon for the first time. The total length of the mitogenome was 17,236 bp with the base composition of 30.2% for A, 24.0% for T, 31.9% for C, and 13.9% for G and an A-T (54.2 %)-rich feature was detected. It harbored 13 protein-coding genes, 2 ribosomal RNA genes, 22 transfer RNA genes and 1 non-coding control region (D-loop region). The arrangement of all genes was identical to the typical mitochondrial genomes of pigeon. The complete mitochondrial genome sequence of ice pigeon would serve as an important data set of the germplasm resources for further study.

  2. Ice-sheet model sensitivities to environmental forcing and their use in projecting future sea level (the SeaRISE project)

    OpenAIRE

    Bindschadler, Robert A.; Nowicki, Sophie; Abe-Ouchi, Ayako; Aschwanden, Andy; Choi, Hyeungu; Fastook, Jim; Granzow, Glen; Greve, Ralf; Gutowski, Gail; Herzfeld, Ute; Jackson, Charles; Johnson, Jesse; Khroulev, Constantine; Levermann, Anders; Lipscomb, William H.

    2013-01-01

    Ten ice-sheet models are used to study sensitivity of the Greenland and Antarctic ice sheets to prescribed changes of surface mass balance, sub-ice-shelf melting and basal sliding. Results exhibit a large range in projected contributions to sea-level change. In most cases, the ice volume above flotation lost is linearly dependent on the strength of the forcing. Combinations of forcings can be closely approximated by linearly summing the contributions from single forcing experiments, suggestin...

  3. Global warming: Sea ice and snow cover

    International Nuclear Information System (INIS)

    Walsh, J.E.

    1993-01-01

    In spite of differences among global climate simulations under scenarios where atmospheric CO 2 is doubled, all models indicate at least some amplification of greenouse warming at the polar regions. Several decades of recent data on air temperature, sea ice, and snow cover of the high latitudes of the Northern Hemisphere are summarized to illustrate the general compatibility of recent variations in those parameters. Despite a data void over the Arctic Ocean, some noteworthy patterns emerge. Warming dominates in winter and spring, as projected by global climate models, with the warming strongest over subpolar land areas of Alaska, northwestern Canada, and northern Eurasia. A time-longitude summary of Arctic sea ice variations indicates that timescales of most anomalies range from several months to several years. Wintertime maxima of total sea ice extent contain no apparent secular trends. The statistical significance of trends in recent sea ice variations was evaluated by a Monte Carlo procedure, showing a statistically significant negative trend in the summer. Snow cover data over the 20-y period of record show a noticeable decrease of Arctic snow cover in the late 1980s. This is of potential climatic significance since the accompanying decrease of surface albedo leads to a rapid increase of solar heating. 21 refs., 3 figs., 1 tab

  4. Canadian snow and sea ice: historical trends and projections

    Science.gov (United States)

    Mudryk, Lawrence R.; Derksen, Chris; Howell, Stephen; Laliberté, Fred; Thackeray, Chad; Sospedra-Alfonso, Reinel; Vionnet, Vincent; Kushner, Paul J.; Brown, Ross

    2018-04-01

    The Canadian Sea Ice and Snow Evolution (CanSISE) Network is a climate research network focused on developing and applying state of the art observational data to advance dynamical prediction, projections, and understanding of seasonal snow cover and sea ice in Canada and the circumpolar Arctic. Here, we present an assessment from the CanSISE Network on trends in the historical record of snow cover (fraction, water equivalent) and sea ice (area, concentration, type, and thickness) across Canada. We also assess projected changes in snow cover and sea ice likely to occur by mid-century, as simulated by the Coupled Model Intercomparison Project Phase 5 (CMIP5) suite of Earth system models. The historical datasets show that the fraction of Canadian land and marine areas covered by snow and ice is decreasing over time, with seasonal and regional variability in the trends consistent with regional differences in surface temperature trends. In particular, summer sea ice cover has decreased significantly across nearly all Canadian marine regions, and the rate of multi-year ice loss in the Beaufort Sea and Canadian Arctic Archipelago has nearly doubled over the last 8 years. The multi-model consensus over the 2020-2050 period shows reductions in fall and spring snow cover fraction and sea ice concentration of 5-10 % per decade (or 15-30 % in total), with similar reductions in winter sea ice concentration in both Hudson Bay and eastern Canadian waters. Peak pre-melt terrestrial snow water equivalent reductions of up to 10 % per decade (30 % in total) are projected across southern Canada.

  5. Viscosity of rock-ice mixtures and applications to the evolution of icy satellites

    Science.gov (United States)

    Friedson, A. J.; Stevenson, D. J.

    1983-01-01

    Theory and experiments are used to establish lower and upper bounds on the ratio of actual viscosity to pure ice viscosity for a suspension of rock particles in a water ice matrix. A rheological model for rock-ice mixtures is described, establishing bounds for the range of possible viscosity enhancements provided by a suspension of silicate spheres in an ice matrix. A parametrized thermal convection model is described and used to determine a criterion for criticality, defined as the heat flow and/or silicate volume fraction for which the satellite temperature profile intercepts the melting curve of water ice. The consequences of achieving this critical state are examined, and it is shown that under certain circumstances a 'runaway' differentiation can occur in which the silicates settle to form a core and extensive melting of water ice takes place, the latent heat being supplied by the gravitational energy of differentiation. A possible application of these results to Ganymede and Callisto is described.

  6. A multivariate analysis of Antarctic sea ice since 1979

    Energy Technology Data Exchange (ETDEWEB)

    Magalhaes Neto, Newton de; Evangelista, Heitor [Universidade do Estado do Rio de Janeiro (Uerj), LARAMG - Laboratorio de Radioecologia e Mudancas Globais, Maracana, Rio de Janeiro, RJ (Brazil); Tanizaki-Fonseca, Kenny [Universidade do Estado do Rio de Janeiro (Uerj), LARAMG - Laboratorio de Radioecologia e Mudancas Globais, Maracana, Rio de Janeiro, RJ (Brazil); Universidade Federal Fluminense (UFF), Dept. Analise Geoambiental, Inst. de Geociencias, Niteroi, RJ (Brazil); Penello Meirelles, Margareth Simoes [Universidade do Estado do Rio de Janeiro (UERJ)/Geomatica, Maracana, Rio de Janeiro, RJ (Brazil); Garcia, Carlos Eiras [Universidade Federal do Rio Grande (FURG), Laboratorio de Oceanografia Fisica, Rio Grande, RS (Brazil)

    2012-03-15

    Recent satellite observations have shown an increase in the total extent of Antarctic sea ice, during periods when the atmosphere and oceans tend to be warmer surrounding a significant part of the continent. Despite an increase in total sea ice, regional analyses depict negative trends in the Bellingshausen-Amundsen Sea and positive trends in the Ross Sea. Although several climate parameters are believed to drive the formation of Antarctic sea ice and the local atmosphere, a descriptive mechanism that could trigger such differences in trends are still unknown. In this study we employed a multivariate analysis in order to identify the response of the Antarctic sea ice with respect to commonly utilized climate forcings/parameters, as follows: (1) The global air surface temperature, (2) The global sea surface temperature, (3) The atmospheric CO{sub 2} concentration, (4) The South Annular Mode, (5) The Nino 3, (6) The Nino (3 + 4, 7) The Nino 4, (8) The Southern Oscillation Index, (9) The Multivariate ENSO Index, (10) the Total Solar Irradiance, (11) The maximum O{sub 3} depletion area, and (12) The minimum O{sub 3} concentration over Antarctica. Our results indicate that western Antarctic sea ice is simultaneously impacted by several parameters; and that the minimum, mean, and maximum sea ice extent may respond to a separate set of climatic/geochemical parameters. (orig.)

  7. Effect of ice surface size on collision rates and head impacts at the World Junior Hockey Championships, 2002 to 2004.

    Science.gov (United States)

    Wennberg, Richard

    2005-03-01

    To determine if collision rates and head impacts in elite junior hockey differed between games played on the small North American ice surface (85 ft wide), an intermediate-size Finnish ice surface (94 ft wide), and the large standard international ice surface (100 ft wide). Videotape analysis of all games involving Team Canada from the 2002 (large ice, Czech Republic), 2003 (small ice, Canada), and 2004 (intermediate ice, Finland) World Junior Championships. All collisions were counted and separated into various categories (volitional player/player bodychecks, into boards or open ice, plus accidental/incidental player/boards, player/ice, head/stick, head/puck). Further subdivisions included collisions involving the head directly or indirectly and notably severe head impacts. Small, intermediate, and large ice surface mean collisions/game, respectively, were 295, 258, 222, total collisions; 251, 220, 181, volitional bodychecks; 126, 115, 88, into boards; 125, 106, 93, open ice; 71, 52, 44, total head; 44, 36, 30, indirect head; 26, 16, 13, direct head; and 1.3, 0.5, 0.3, severe head (P < 0.05 for small-intermediate ice and intermediate-large ice differences in total collisions; P < 0.005 for small-large ice difference; P < 0.05 for small-intermediate ice differences in head impacts; P < 0.01 for small-large ice differences in total and severe head impacts). There is a significant inverse correlation between ice size and collision rates in elite hockey, including direct, indirect, and severe head impacts. These findings suggest that uniform usage of the larger international rinks could reduce the risk of injury, and specifically, concussions in elite hockey by decreasing the occurrence of collisions and head impacts.

  8. Perennial water stratification and the role of freshwater in the mass balance of Arctic ice shelves and multiyear landfast sea ice

    International Nuclear Information System (INIS)

    Jeffries, M.O.

    1991-01-01

    A number of the ice shelves of northern Ellesmere Island in the Canadian High Arctic owe their origin to multiyear landfast sea ice (MLSI) growth during the post-Hypsithermal cooling ca. 3,000-4,000 BP. Since they grew in response to an arctic-wide climatic deterioration and contain evidence of occasional post-4,000 BP climatic ameliorations, they may be expected to be sensitive to future global climate changes manifested in the High Arctic. The purpose of this paper is to examine ice-ocean interactions and feedbacks, and the response of the ice shelves and the MLSI to the improved summer climate of the last ca. 100 years, and implications for the future. There is good evidence that there has been a negative surface mass balance since the turn of the century. Mass balance measurements on the Ward Hunt Ice Shelf between 1966 and 1985 indicate a total ice loss of 1.371 m at a mean annual rate of 68.5 mm. The interannual pattern of accumulation and ablation and the long-term losses on the ice shelf are similar to other Canadian High Arctic glacier mass balance records. It is evident from water and ice core records of salinity, δ 18 0 and tritium, that perennial water stratification is common below and behind the ice shelves and MLSI. The coastal waters are highly stratified, with anything from 0.5 m to 41.0 m of freshwater interposed between the overlying ice and underlying seawater. The primary source of the freshwater is summer run-off of snow-meltwater from the adjacent land and from the ice itself. There is minimal mixing between the influent freshwater and seawater, and the freshwater is either dammed behind the ice shelves and the MLSI, with subsequent under-ice freshwater outflows, or pooled in under-ice depressions

  9. An Initial Study of the Fundamentals of Ice Crystal Icing Physics in the NASA Propulsion Systems Laboratory

    Science.gov (United States)

    Struk, Peter M.; Ratvasky, Thomas P.; Bencic, Timothy J.; Van Zante, Judith F.; King, Michael C.; Tsao, Jen-Ching; Bartkus, Tadas P.

    2017-01-01

    This paper presents results from an initial study of the fundamental physics of ice-crystal ice accretion using the NASA Propulsion Systems Lab (PSL). Ice accretion due to the ingestion of ice-crystals is being attributed to numerous jet-engine power-loss events. The NASA PSL is an altitude jet-engine test facility which has recently added a capability to inject ice particles into the flow. NASA is evaluating whether this facility, in addition to full-engine and motor-driven-rig tests, can be used for more fundamental ice-accretion studies that simulate the different mixed-phase icing conditions along the core flow passage of a turbo-fan engine compressor. The data from such fundamental accretion tests will be used to help develop and validate models of the accretion process. The present study utilized a NACA0012 airfoil. The mixed-phase conditions were generated by partially freezing the liquid-water droplets ejected from the spray bars. This paper presents data regarding (1) the freeze out characteristics of the cloud, (2) changes in aerothermal conditions due to the presence of the cloud, and (3) the ice accretion characteristics observed on the airfoil model. The primary variable in this test was the PSL plenum humidity which was systematically varied for two duct-exit-plane velocities (85 and 135 ms) as well as two particle size clouds (15 and 50 m MVDi). The observed clouds ranged from fully glaciated to fully liquid, where the liquid clouds were at least partially supercooled. The air total temperature decreased at the test section when the cloud was activated due to evaporation. The ice accretions observed ranged from sharp arrow-like accretions, characteristic of ice-crystal erosion, to cases with double-horn shapes, characteristic of supercooled water accretions.

  10. Thin Sea Ice, Thick Snow, and Widespread Negative Freeboard Observed During N-ICE2015 North of Svalbard

    Science.gov (United States)

    Rösel, Anja; Itkin, Polona; King, Jennifer; Divine, Dmitry; Wang, Caixin; Granskog, Mats A.; Krumpen, Thomas; Gerland, Sebastian

    2018-02-01

    In recent years, sea-ice conditions in the Arctic Ocean changed substantially toward a younger and thinner sea-ice cover. To capture the scope of these changes and identify the differences between individual regions, in situ observations from expeditions are a valuable data source. We present a continuous time series of in situ measurements from the N-ICE2015 expedition from January to June 2015 in the Arctic Basin north of Svalbard, comprising snow buoy and ice mass balance buoy data and local and regional data gained from electromagnetic induction (EM) surveys and snow probe measurements from four distinct drifts. The observed mean snow depth of 0.53 m for April to early June is 73% above the average value of 0.30 m from historical and recent observations in this region, covering the years 1955-2017. The modal total ice and snow thicknesses, of 1.6 and 1.7 m measured with ground-based EM and airborne EM measurements in April, May, and June 2015, respectively, lie below the values ranging from 1.8 to 2.7 m, reported in historical observations from the same region and time of year. The thick snow cover slows thermodynamic growth of the underlying sea ice. In combination with a thin sea-ice cover this leads to an imbalance between snow and ice thickness, which causes widespread negative freeboard with subsequent flooding and a potential for snow-ice formation. With certainty, 29% of randomly located drill holes on level ice had negative freeboard.

  11. Remote Sensing of Crystal Shapes in Ice Clouds

    Science.gov (United States)

    van Diedenhoven, Bastiaan

    2017-01-01

    Ice crystals in clouds exist in a virtually limitless variation of geometries. The most basic shapes of ice crystals are columnar or plate-like hexagonal prisms with aspect ratios determined by relative humidity and temperature. However, crystals in ice clouds generally display more complex structures owing to aggregation, riming and growth histories through varying temperature and humidity regimes. Crystal shape is relevant for cloud evolution as it affects microphysical properties such as fall speeds and aggregation efficiency. Furthermore, the scattering properties of ice crystals are affected by their general shape, as well as by microscopic features such as surface roughness, impurities and internal structure. To improve the representation of ice clouds in climate models, increased understanding of the global variation of crystal shape and how it relates to, e.g., location, cloud temperature and atmospheric state is crucial. Here, the remote sensing of ice crystal macroscale and microscale structure from airborne and space-based lidar depolarization observations and multi-directional measurements of total and polarized reflectances is reviewed. In addition, a brief overview is given of in situ and laboratory observations of ice crystal shape as well as the optical properties of ice crystals that serve as foundations for the remote sensing approaches. Lidar depolarization is generally found to increase with increasing cloud height and to vary with latitude. Although this variation is generally linked to the variation of ice crystal shape, the interpretation of the depolarization remains largely qualitative and more research is needed before quantitative conclusions about ice shape can be deduced. The angular variation of total and polarized reflectances of ice clouds has been analyzed by numerous studies in order to infer information about ice crystal shapes from them. From these studies it is apparent that pristine crystals with smooth surfaces are generally

  12. Experimental provocation of 'ice-cream headache' by ice cubes and ice water.

    Science.gov (United States)

    Mages, Stephan; Hensel, Ole; Zierz, Antonia Maria; Kraya, Torsten; Zierz, Stephan

    2017-04-01

    Background There are various studies on experimentally provoked 'ice-cream headache' or 'headache attributed to ingestion or inhalation of a cold stimulus' (HICS) using different provocation protocols. The aim of this study was to compare two provocation protocols. Methods Ice cubes pressed to the palate and fast ingestion of ice water were used to provoke HICS and clinical features were compared. Results The ice-water stimulus provoked HICS significantly more often than the ice-cube stimulus (9/77 vs. 39/77). Ice-water-provoked HICS had a significantly shorter latency (median 15 s, range 4-97 s vs. median 68 s, range 27-96 s). There was no difference in pain localisation. Character after ice-cube stimulation was predominantly described as pressing and after ice-water stimulation as stabbing. A second HICS followed in 10/39 (26%) of the headaches provoked by ice water. Lacrimation occurred significantly more often in volunteers with than in those without HICS. Discussion HICS provoked by ice water was more frequent, had a shorter latency, different pain character and higher pain intensity than HICS provoked by ice cubes. The finding of two subsequent HICS attacks in the same volunteers supports the notion that two types of HICS exist. Lacrimation during HICS indicates involvement of the trigeminal-autonomic reflex.

  13. GPR capabilities for ice thickness sampling of low salinity ice and for detecting oil in ice

    Energy Technology Data Exchange (ETDEWEB)

    Lalumiere, Louis [Sensors by Design Ltd. (Canada)

    2011-07-01

    This report discusses the performance and capabilities test of two airborne ground-penetrating radar (GPR) systems of the Bedford Institute of Oceanography (BIO), Noggin 1000 and Noggin 500, for monitoring low salinity snow and ice properties which was used to measure the thickness of brackish ice on Lake Melville in Labrador and on a tidal river in Prince Edward Island. The work of other researchers is documented and the measurement techniques proposed are compared to the actual GPR approach. Different plots of GPR data taken over snow and freshwater ice and over ice with changing salinity are discussed. An interpretation of brackish ice GPR plots done by the Noggin 1000 and Noggin 500 systems is given based on resolution criterion. Additionally, the capability of the BIO helicopter-borne GPR to detect oil-in-ice has been also investigated, and an opinion on the likelihood of the success of GPR as an oil-in-ice detector is given.

  14. Thermodynamic and dynamic ice thickness contributions in the Canadian Arctic Archipelago in NEMO-LIM2 numerical simulations

    Science.gov (United States)

    Hu, Xianmin; Sun, Jingfan; Chan, Ting On; Myers, Paul G.

    2018-04-01

    Sea ice thickness evolution within the Canadian Arctic Archipelago (CAA) is of great interest to science, as well as local communities and their economy. In this study, based on the NEMO numerical framework including the LIM2 sea ice module, simulations at both 1/4 and 1/12° horizontal resolution were conducted from 2002 to 2016. The model captures well the general spatial distribution of ice thickness in the CAA region, with very thick sea ice (˜ 4 m and thicker) in the northern CAA, thick sea ice (2.5 to 3 m) in the west-central Parry Channel and M'Clintock Channel, and thin ( Program data at first-year landfast ice sites except at the northern sites with high concentration of old ice. At 1/4 to 1/12° scale, model resolution does not play a significant role in the sea ice simulation except to improve local dynamics because of better coastline representation. Sea ice growth is decomposed into thermodynamic and dynamic (including all non-thermodynamic processes in the model) contributions to study the ice thickness evolution. Relatively smaller thermodynamic contribution to ice growth between December and the following April is found in the thick and very thick ice regions, with larger contributions in the thin ice-covered region. No significant trend in winter maximum ice volume is found in the northern CAA and Baffin Bay while a decline (r2 ≈ 0.6, p < 0.01) is simulated in Parry Channel region. The two main contributors (thermodynamic growth and lateral transport) have high interannual variabilities which largely balance each other, so that maximum ice volume can vary interannually by ±12 % in the northern CAA, ±15 % in Parry Channel, and ±9 % in Baffin Bay. Further quantitative evaluation is required.

  15. Animals and ICE

    DEFF Research Database (Denmark)

    van Hemmen, J Leo; Christensen-Dalsgaard, Jakob; Carr, Catherine E

    2016-01-01

    experimental and mathematical foundation, it is known that there is a low-frequency regime where the internal time difference (iTD) as perceived by the animal may well be 2-5 times higher than the external ITD, the interaural time difference, and that there is a frequency plateau over which the fraction i......TD/ITD is constant. There is also a high-frequency regime where the internal level (amplitude) difference iLD as perceived by the animal is much higher than the interaural level difference ILD measured externally between the two ears. The fundamental tympanic frequency segregates the two regimes. The present special...... issue devoted to "internally coupled ears" provides an overview of many aspects of ICE, be they acoustic, anatomical, auditory, mathematical, or neurobiological. A focus is on the hotly debated topic of what aspects of ICE animals actually exploit neuronally to localize a sound source....

  16. Skating on slippery ice

    Directory of Open Access Journals (Sweden)

    J. M. J. van Leeuwen

    2017-12-01

    Full Text Available The friction of a stationary moving skate on smooth ice is investigated, in particular in relation to the formation of a thin layer of water between skate and ice. It is found that the combination of ploughing and sliding gives a friction force that is rather insensitive for parameters such as velocity and temperature. The weak dependence originates from the pressure adjustment inside the water layer. For instance, high velocities, which would give rise to high friction, also lead to large pressures, which, in turn, decrease the contact zone and so lower the friction. The theory is a combination and completion of two existing but conflicting theories on the formation of the water layer.

  17. Theory of amorphous ices.

    Science.gov (United States)

    Limmer, David T; Chandler, David

    2014-07-01

    We derive a phase diagram for amorphous solids and liquid supercooled water and explain why the amorphous solids of water exist in several different forms. Application of large-deviation theory allows us to prepare such phases in computer simulations. Along with nonequilibrium transitions between the ergodic liquid and two distinct amorphous solids, we establish coexistence between these two amorphous solids. The phase diagram we predict includes a nonequilibrium triple point where two amorphous phases and the liquid coexist. Whereas the amorphous solids are long-lived and slowly aging glasses, their melting can lead quickly to the formation of crystalline ice. Further, melting of the higher density amorphous solid at low pressures takes place in steps, transitioning to the lower-density glass before accessing a nonequilibrium liquid from which ice coarsens.

  18. Modeling of radiation transport in coupled atmosphere-snow-ice-ocean systems

    International Nuclear Information System (INIS)

    Stamnes, K.; Hamre, B.; Stamnes, J.J.; Ryzhikov, G.; Biryulina, M.; Mahoney, R.; Hauss, B.; Sei, A.

    2011-01-01

    A radiative transfer model for coupled atmosphere-snow-ice-ocean systems (CASIO-DISORT) is used to develop accurate and efficient tools for computing the bidirectional reflectance distribution function (BRDF) of sea ice for a wide range of situations occurring in nature. These tools include a method to generate sea ice inherent optical properties (IOPs: single-scattering albedo, extinction optical depth, and scattering asymmetry parameter) for any wavelength between 300 and 4000 nm as a function of sea ice physical parameters including real and imaginary parts of the sea ice refractive index, brine pocket concentration and effective brine pocket size, air bubble concentration and effective air bubble size, volume fraction of ice impurities and impurity absorption coefficient, and sea ice thickness. The CASIO-DISORT code was used to compute look-up tables (LUTs) of the Fourier expansion coefficients of the BRDF as a function of angles of illumination and observation, sea ice IOPs, and ocean albedo. By interpolation in the LUTs one efficiently obtains accurate BRDF values. To include snow on the ice we modified DISORT2 to accept Fourier expansion coefficients for the BDRF as input instead of the BRDF itself, thereby reducing the computation time by a factor of about 60. The BRDF computed by CASIO-DISORT or retrieved from the LUTs applies to diffuse light only. To remedy this shortcoming we added a specular Gaussian beam component to the new BRDF tool and verified that it works well for BRDFs for bare and snow-covered sea ice.

  19. [Investigation of Helicobacter pylori iceA1 and iceA2 genes in patients with chronic gastritis and gastric cancer].

    Science.gov (United States)

    Ciftci, Ihsan Hakkı; Uslan, Ihsan; Dilek, Fatma Hüsniye; Aşık, Gülşah; Ozgür, Mihrican Aydın; Dilek, Osman Nuri

    2011-04-01

    Several virulence factors of Helicobacter pylori play crucial role in the pathogenesis of the infections.H.pylori iceA gene which is induced by the contact with epithelium during the attachment of bacterium to the gastric mucosa, possess two variants (iceA1 and iceA2). Although there are some data indicating the relationship between H.pylori iceA1 and peptic ulcer, this concept is still controversial. The aims of this study were to investigate the presence and prevalence of H.pylori iceA1 and iceA2 gene regions in the tissue samples of patients diagnosed as chronic gastritis and gastric cancer, and to evaluate whether any correlation existed between these genotypes and clinical manifestations. A total of 109 tissue samples obtained from chronic gastritis (n= 55) and gastric cancer (n= 54) patients whose H.pylori infections have been confirmed by histopathologic examination of biopsy samples, were included in the study. The presence of H.pylori in the samples were also confirmed by amplification of the ureA gene region by inhouse polymerase chain reaction (PCR). H.pylori iceA1 and iceA2 genes were directly genotyped with the use of specific primers in the gastric biopsy specimens by PCR. The total positivity rates of iceA1 and ice- A2 genotypes in patients were found as 58% (63/109) and 24% (26/109), respectively. With the special attention to chronic gastritis and gastric cancer patients, the frequencies of iceA1 gene were 51% (28/55) and 65% (35/54), while the frequencies of iceA2 gene were 20% (11/55) and 28% (15/54), respectively. The difference of positivity rates of iceA1 and iceA2 genotypes between the patient groups were not statistically significant (p> 0.05). There was also no statistically significant correlation between the genotypes and clinical manifestation (r> 0.01). As a result, H.pylori iceA1 genotype was predominant (58%) in chronic gastritis and gastric cancer patients in our region, however the prevalence of iceA2 genotype was lower (24

  20. The isotopic composition of methane in polar ice cores

    Science.gov (United States)

    Craig, H.; Chou, C. C.; Welhan, J. A.; Stevens, C. M.; Engelkemeir, A.

    1988-01-01

    Air bubbles in polar ice cores indicate that about 300 years ago the atmospheric mixing ratio of methane began to increase rapidly. Today the mixing ratio is about 1.7 parts per million by volume, and, having doubled once in the past several hundred years, it will double again in the next 60 years if current rates continue. Carbon isotope ratios in methane up to 350 years in age have been measured with as little as 25 kilograms of polar ice recovered in 4-meter-long ice-core segments. The data show that: (1) in situ microbiology or chemistry has not altered the ice-core methane concentrations, and (2) that the carbon-13 to carbon-12 ratio of atmospheric CH4 in ice from 100 years and 300 years ago was about 2 per mil lower than at present. Atmospheric methane has a rich spectrum of isotopic sources: the ice-core data indicate that anthropogenic burning of the earth's biomass is the principal cause of the recent C-13H4 enrichment, although other factors may also contribute.

  1. Arctic Ice Studies

    Science.gov (United States)

    1993-02-01

    i heoriotlscale wace s 50 kin wthe11 aii vertical leadi tof M o.ChrlesA Lcur the siir-ai’.orc~5 . ~ ~G. RLI Lt(lWA~S II I Shuchln P A P Ut alI 9...can be utilized msccesafully. distinguish between these two major ice types and open I. INTRODUCTION water. S THE geophysical and economic importance of

  2. Car engine breather icing

    OpenAIRE

    Horoufi, Aryan

    2012-01-01

    Icing in an engine breather system can block the engine breather pipe, cause excessive crankcase pressure and degrade the engine performance. In this project, a numerical study, experimental tests and CFD analysis are employed in order to understand condensation and the extent of freezing inside a vertical pipe, a horizontal pipe and a T-joint pipe which are exposed to an external convective cooling. The pipe internal flow is assumed to be a vapour/air mixture. This study has l...

  3. Marginal Ice Zone Bibliography.

    Science.gov (United States)

    1985-06-01

    Tsunamis, Gravimetry , Earth Tides, World Data Center A: Oceanography Recent Movements of the Earth’s National Oceanographic Data Center Crust...sufficiently low, the dissolved salts precipitate out in the form of solid hydrates. It has been proposed that these solid hydrates add to the overall...strength of the ice. The first salt hydrate to precipitate should be that of sodium sul- * fate, Na2SO4IOH2O (the sulfate ion is the second most

  4. Unidirectional spreading of oil under solid ice

    International Nuclear Information System (INIS)

    Weerasuriya, S.A.; Yapa, P.D.

    1993-01-01

    Equations are presented to describe the unidirectional spreading of oil under solid ice covers floating in calm water. These spreading equations are derived using a simplified form of the Navier-Stokes equations, and cover both the constant discharge and the constant volume modes. An equation for computing final slick length is also given. Laboratory experiments using physical models were conducted to verify the equations. The experiments used oils of different viscosities, ice cover roughnesses varying from smooth to rough, and a variety of discharge conditions. The emphasis of the study was on the dominant spreading mechanism for oil under ice, which is the buoyancy-viscous phase. The laboratory results agree closely with the theoretical predictions. Discrepancies can be attributed to the experimental difficulties and errors introduced from the assumptions made in deriving the theory. The equations presented will be useful in computing spreading rate during an accidental oil spill or in contingency planning. The equations are simple to use, suitable for hand calculations or for incorporation into numerical models for oil spill simulation. 24 refs., 10 figs., 1 tab

  5. Ice condenser experimental plan

    International Nuclear Information System (INIS)

    Kannberg, L.D.; Piepel, G.F.; Owczarski, P.C.; Liebetrau, A.M.

    1986-01-01

    An experimental plan is being developed to validate the computer code ICEDF. The code was developed to estimate the extent of aerosol retention in the ice compartments of pressurized water reactor ice condenser containment systems during severe accidents. The development of the experimental plan began with review of available information on the conditions under which the code will be applied. Computer-generated estimates of thermohydraulic and aerosol conditions entering the ice condenser were evaluated and along with other information, used to generate design criteria. The design criteria have been used for preliminary test assembly design and for generation of statistical test designs. Consideration of the phenomena to be evaluated in the testing program, as well as equipment and measurement limitations, have led to changes in the design criteria and to subsequent changes in the test assembly design and statistical test design. The overall strategy in developing the experimental plan includes iterative generation and evaluation of candidate test designs using computer codes for statistical test design and ICEDF for estimation of experimental results. Estimates of experimental variability made prior to actual testing will be verified by replicate testing at preselected design points

  6. Organic components in hair-ice

    Science.gov (United States)

    Hofmann, Diana; Steffen, Bernhard; Disko, Ulrich; Wagner, Gerhard; Mätzler, Christian

    2013-04-01

    Hair-ice is a rather unknown phenomenon. In contrast to generally known frost needles, originating from atmospheric water and expanding e.g. from plant surfaces in all directions, hair ice grows from the basis of wet, rotten hardwood. The hair-like, flexible, linear structures may reach up to 10 cm in length without any ramifications. Hair-ice appears to be related to the biological activity of a fungus mycelium within the wood. Hair-ice can attract winter-active Collemboles (snow flea, Isotoma nivalis). At the onset of hair-ice melt a very thin fibre becomes apparent, which carries brownish pearl-like water drops. Therefore, it is supposed that organic substances are inherent, which could possibly act as freezing catalyst as well as recrystallization inhibitor. The aim of this work was the chemical characterization of organic substances contained in hair-ice. First analyses of melted hair-ice show a total organic carbon (TOC) value of 235 mg/l in contrast to 11 mg/l total nitrogen. Most of inherent nitrogen (70 %) exists thereby as ammonium. Screened by different (mass spectrometric) methods, no evidence could be found for the initially expected organic substances like proteins, lipids, small volatile substances or carboxylic acids. By coupling of Ultra Performance Liquid Chromatography with a triple quadrupol mass spectrometer (UPLC-MS) a non-resolved chromatogram from a melted hair-ice sample was received. Averaged spectra from different regions are similar among themselves with a broad peak spreading over the mass range 100-650 Da with favored intense, odd-numbered peaks. Such spectra are similar to dissolved organic matter (DOM), known e.g. from terrestrial and marine waters, soil extracts or aerosols. In the next step, samples were desalted and concentrated by solid phase extraction (SPE) and subsequently analyzed by flow injection analysis (FIA) in a Fourier Transform Ion Cyclotron Resonance Mass Spectrometer (FTICR-MS), equipped with an ESI source and a 7 T

  7. Ikaite crystal distribution in Arctic winter sea ice and implications for CO2 system dynamics

    Science.gov (United States)

    Rysgaard, S.; Søgaard, D. H.; Cooper, M.; Pućko, M.; Lennert, K.; Papakyriakou, T. N.; Wang, F.; Geilfus, N. X.; Glud, R. N.; Ehn, J.; McGinnnis, D. F.; Attard, K.; Sievers, J.; Deming, J. W.; Barber, D.

    2012-12-01

    The precipitation of ikaite (CaCO3·6H2O) in polar sea ice is critical to the efficiency of the sea ice-driven carbon pump and potentially important to the global carbon cycle, yet the spatial and temporal occurrence of ikaite within the ice is poorly known. We report unique observations of ikaite in unmelted ice and vertical profiles of ikaite abundance and concentration in sea ice for the crucial season of winter. Ice was examined from two locations: a 1 m thick land-fast ice site and a 0.3 m thick polynya site, both in the Young Sound area (74° N, 20° W) of NE Greenland. Ikaite crystals, ranging in size from a few µm to 700 µm were observed to concentrate in the interstices between the ice platelets in both granular and columnar sea ice. In vertical sea-ice profiles from both locations, ikaite concentration determined from image analysis, decreased with depth from surfaceice values of 700-900 µmol kg-1 ice (~ 25 × 106 crystals kg-1) to bottom-layer values of 100-200 µmol kg-1 ice (1-7 × 106 kg-1), all of which are much higher (4-10 times) than those reported in the few previous studies. Direct measurements of total alkalinity (TA) in surface layers fell within the same range as ikaite concentration whereas TA concentrations in bottom layers were twice as high. This depth-related discrepancy suggests interior ice processes where ikaite crystals form in surface sea ice layers and partly dissolved in bottom layers. From these findings and model calculations we relate sea ice formation and melt to observed pCO2 conditions in polar surface waters, and hence, the air-sea CO2 flux.

  8. Prognostic significance of preoperative metabolic tumour volume and total lesion glycolysis measured by {sup 18}F-FDG PET/CT in squamous cell carcinoma of the oral cavity

    Energy Technology Data Exchange (ETDEWEB)

    Ryu, In Sun; Roh, Jong-Lyel; Choi, Seung-Ho; Nam, Soon Yuhl [University of Ulsan College of Medicine, Department of Otolaryngology, Asan Medical Center, Seoul (Korea, Republic of); Kim, Jae Seung [University of Ulsan College of Medicine, Department of Nuclear Medicine, Asan Medical Center, Seoul (Korea, Republic of); Cho, Kyung-Ja [University of Ulsan College of Medicine, Department of Pathology, Asan Medical Center, Seoul (Korea, Republic of); Kim, Sang Yoon [University of Ulsan College of Medicine, Department of Otolaryngology, Asan Medical Center, Seoul (Korea, Republic of); Biomedical Research Institute, Korean Institute of Science and Technology, Seoul (Korea, Republic of)

    2014-03-15

    Metabolic tumour volume (MTV) and total lesion glycolysis (TLG) from {sup 18}F-FDG PET/CT are emerging prognostic biomarkers in human solid cancers; yet few studies have investigated their clinical and prognostic significance in oral cavity squamous cell carcinoma (OSCC). The present retrospective study evaluated the utility of pretreatment MTV and TLG measured by {sup 18}F-FDG PET/CT to predict survival and occult metastasis (OM) in OSCC. Of 162 patients with OSCC evaluated preoperatively by {sup 18}F-FDG PET/CT, 105 who underwent definitive surgery with or without adjuvant therapy were eligible. Maximum standardized uptake value (SUV{sub max}), MTV and TLG were measured. For calculation of MTV, 3-D regions of interest were drawn and a SUV threshold of 2.5 was used for defining regions. Univariate and multivariate analyses identified clinicopathological and imaging variables associated with OM, disease-free survival (DFS) and overall survival (OS). The median (range) SUV{sub max}, MTV and TLG were 7.3 (0.7-41.9), 4.5 ml (0.7-115.1 ml) and 18.3 g (2.4-224.1 g), respectively. Of 53 patients with clinically negative lymph nodes, OM was detected in 19 (36 %). By univariate and multivariate analyses, MTV (P = 0.018) and TLG (P = 0.011) were both independent predictive factors for OM, although they were not independent of each other. The 4-year DFS and OS rates were 53.0 % and 62.0 %, respectively. Univariate and multivariate analyses revealed that MTV (P = 0.001) and TLG (P = 0.006), with different cut-off levels, were both independent predictive factors for DFS, although they were not independent of each other, and MTV (P = 0.001), TLG (P = 0.002) and the involved resection margin (P = 0.007) were independent predictive factors for OS. Pretreatment MTV and TLG may be useful in stratifying the likelihood of survival and predicting OM in OSCC. (orig.)

  9. IceCube systematic errors investigation: Simulation of the ice

    Energy Technology Data Exchange (ETDEWEB)

    Resconi, Elisa; Wolf, Martin [Max-Planck-Institute for Nuclear Physics, Heidelberg (Germany); Schukraft, Anne [RWTH, Aachen University (Germany)

    2010-07-01

    IceCube is a neutrino observatory for astroparticle and astronomy research at the South Pole. It uses one cubic kilometer of Antartica's deepest ice (1500 m-2500 m in depth) to detect Cherenkov light, generated by charged particles traveling through the ice, with an array of phototubes encapsulated in glass pressure spheres. The arrival time as well as the charge deposited of the detected photons represent the base measurements that are used for track and energy reconstruction of those charged particles. The optical properties of the deep antarctic ice vary from layer to layer. Measurements of the ice properties and their correct modeling in Monte Carlo simulation is then of primary importance for the correct understanding of the IceCube telescope behavior. After a short summary about the different methods to investigate the ice properties and to calibrate the detector, we show how the simulation obtained by using this information compares to the measured data and how systematic errors due to uncertain ice properties are determined in IceCube.

  10. Experiments in Ice Contaminant Remanent Magnetization of Dusty Frost Deposits

    Science.gov (United States)

    Grossman, Y.; Aharonson, O.; Shaar, R.

    2017-12-01

    Sedimentary rocks can acquire magnetization in the presence of an external field as grains settle out of suspension in a water column - a process known as Depositional Remanent Magnetization (DRM). In analogy with this, here we propose and experimentally demonstrate a new mechanism for acquisition of magnetization by ice and particulate mixtures which we term Ice Contaminant Remanent Magnetization (ICRM). This phenomenon results from the settling of atmospheric dust containing magnetic particles (e.g. magnetite or other iron oxides). Upon freezing, magnetic dust particles assume a preferential orientation that depends on the external planetary field, resulting in bulk magnetization of the dusty ice. Hence over geologic timescales, the ice stratigraphy is expected to record the geomagnetic history. To test this hypothesis, we designed a set of experiments in which mixtures of ice and dust were deposited in a controlled ambient magnetic field environment. We measured the ratio between the volume normalized magnetization of the dusty ice (m) and the applied field (H) during deposition of the mixture, which is expressed as the effective ICRM susceptibility: m=χICRMH. A magnetic field was applied by a 3-axis Helmholtz coil at the Weizmann Simulating Planetary Ices & Environments Laboratory, and the frozen samples were analyzed in a 2G-Entreprises SQUID Rock Magnetometer at the Hebrew University Institute for Earth Sciences. We measured a clear correlation in amplitude and direction between the ambient magnetic field applied during deposition and the remanent magnetic moment of the resulting samples. We studied various concentrations and particle sizes (diameters 5 µm to 50 µm) of iron and magnetite particles. Effective bulk susceptibilities show a range of values, starting from 10-3 and up to values that saturate the analytical instrument. Our preliminary results indicate that natural ice deposits may acquire variable magnetization due to ICRM, which may in turn be

  11. GREENLAND ICE SHEET CHANGES FROM SPACE USING LASER, RADAR AND

    DEFF Research Database (Denmark)

    Sørensen, Louise Sandberg; Stenseng, Lars; Simonsen, Sebastian Bjerregaard

    2010-01-01

    The Greenland cryosphere is undergoing rapid changes, and these are documented by remote sensing from space. In this paper, an inversion scheme is used to derive mass changes from gravity changes observed by GRACE, and to derive the mean annual mass loss for the Greenland Ice Sheet, which...... is estimated to be 204 Gt/yr for the period 2002-2010. NASA’s laser altimetry satellite ICESat has provided elevation estimates of the ice sheet since January 2003. In order to be able to compare GRACE and ICESat derived results, the ICESat volume change must be converted into a mass change estimate. Therefore...

  12. Bacterial Standing Stock, Activity, and Carbon Production during Formation and Growth of Sea Ice in the Weddell Sea, Antarctica.

    Science.gov (United States)

    Grossmann, S; Dieckmann, G S

    1994-08-01

    Bacterial response to formation and growth of sea ice was investigated during autumn in the northeastern Weddell Sea. Changes in standing stock, activity, and carbon production of bacteria were determined in successive stages of ice development. During initial ice formation, concentrations of bacterial cells, in the order of 1 x 10 to 3 x 10 liter, were not enhanced within the ice matrix. This suggests that physical enrichment of bacteria by ice crystals is not effective. Due to low concentrations of phytoplankton in the water column during freezing, incorporation of bacteria into newly formed ice via attachment to algal cells or aggregates was not recorded in this study. As soon as the ice had formed, the general metabolic activity of bacterial populations was strongly suppressed. Furthermore, the ratio of [H]leucine incorporation into proteins to [H]thymidine incorporation into DNA changed during ice growth. In thick pack ice, bacterial activity recovered and growth rates up to 0.6 day indicated actively dividing populations. However, biomass-specific utilization of organic compounds remained lower than in open water. Bacterial concentrations of up to 2.8 x 10 cells liter along with considerably enlarged cell volumes accumulated within thick pack ice, suggesting reduced mortality rates of bacteria within the small brine pores. In the course of ice development, bacterial carbon production increased from about 0.01 to 0.4 mug of C liter h. In thick ice, bacterial secondary production exceeded primary production of microalgae.

  13. Millennial total sea-level commitments projected with the Earth system model of intermediate complexity LOVECLIM

    International Nuclear Information System (INIS)

    Goelzer, H; Huybrechts, P; Raper, S C B; Loutre, M-F; Goosse, H; Fichefet, T

    2012-01-01

    Sea-level is expected to rise for a long time to come, even after stabilization of human-induced climatic warming. Here we use simulations with the Earth system model of intermediate complexity LOVECLIM to project sea-level changes over the third millennium forced with atmospheric greenhouse gas concentrations that stabilize by either 2000 or 2100 AD. The model includes 3D thermomechanical models of the Greenland and Antarctic ice sheets coupled to an atmosphere and an ocean model, a global glacier melt algorithm to account for the response of mountain glaciers and ice caps, and a procedure for assessing oceanic thermal expansion from oceanic heat uptake. Four climate change scenarios are considered to determine sea-level commitments. These assume a 21st century increase in greenhouse gases according to SRES scenarios B1, A1B and A2 with a stabilization of the atmospheric composition after the year 2100. One additional scenario assumes 1000 years of constant atmospheric composition from the year 2000 onwards. For our preferred model version, we find an already committed total sea-level rise of 1.1 m by 3000 AD. In experiments with greenhouse gas concentration stabilization at 2100 AD, the total sea-level rise ranges between 2.1 m (B1), 4.1 m (A1B) and 6.8 m (A2). In all scenarios, more than half of this amount arises from the Greenland ice sheet, thermal expansion is the second largest contributor, and the contribution of glaciers and ice caps is small as it is limited by the available ice volume of maximally 25 cm of sea-level equivalent. Additionally, we analysed the sensitivity of the sea-level contributions from an ensemble of nine different model versions that cover a large range of climate sensitivity realized by model parameter variations of the atmosphere–ocean model. Selected temperature indices are found to be good predictors for sea-level contributions from the different components of land ice and oceanic thermal expansion after 1000 years. (letter)

  14. Evidence of unfrozen liquids and seismic anisotropy at the base of the polar ice sheets

    Science.gov (United States)

    Wittlinger, Gérard; Farra, Véronique

    2015-03-01

    We analyze seismic data from broadband stations located on the Antarctic and Greenland ice sheets to determine polar ice seismic velocities. P-to-S converted waves at the ice/rock interface and inside the ice sheets and their multiples (the P-receiver functions) are used to estimate in-situ P-wave velocity (Vp) and P-to-S velocity ratio (Vp/Vs) of polar ice. We find that the polar ice sheets have a two-layer structure; an upper layer of variable thickness (about 2/3 of the total thickness) with seismic velocities close to the standard ice values, and a lower layer of approximately constant thickness with standard Vp but ∼25% smaller Vs. The lower layer ceiling corresponds approximately to the -30 °C isotherm. Synthetic modeling of P-receiver functions shows that strong seismic anisotropy and low vertical S velocity are needed in the lower layer. The seismic anisotropy results from the preferred orientation of ice crystal c-axes toward the vertical. The low vertical S velocity may be due to the presence of unfrozen liquids resulting from premelting at grain joints and/or melting of chemical solutions buried in the ice. The strongly preferred ice crystal orientation fabric and the unfrozen fluids may facilitate polar ice sheet basal flow.

  15. Statistical Analyses of High-Resolution Aircraft and Satellite Observations of Sea Ice: Applications for Improving Model Simulations

    Science.gov (United States)

    Farrell, S. L.; Kurtz, N. T.; Richter-Menge, J.; Harbeck, J. P.; Onana, V.

    2012-12-01

    Satellite-derived estimates of ice thickness and observations of ice extent over the last decade point to a downward trend in the basin-scale ice volume of the Arctic Ocean. This loss has broad-ranging impacts on the regional climate and ecosystems, as well as implications for regional infrastructure, marine navigation, national security, and resource exploration. New observational datasets at small spatial and temporal scales are now required to improve our understanding of physical processes occurring within the ice pack and advance parameterizations in the next generation of numerical sea-ice models. High-resolution airborne and satellite observations of the sea ice are now available at meter-scale resolution or better that provide new details on the properties and morphology of the ice pack across basin scales. For example the NASA IceBridge airborne campaign routinely surveys the sea ice of the Arctic and Southern Oceans with an advanced sensor suite including laser and radar altimeters and digital cameras that together provide high-resolution measurements of sea ice freeboard, thickness, snow depth and lead distribution. Here we present statistical analyses of the ice pack primarily derived from the following IceBridge instruments: the Digital Mapping System (DMS), a nadir-looking, high-resolution digital camera; the Airborne Topographic Mapper, a scanning lidar; and the University of Kansas snow radar, a novel instrument designed to estimate snow depth on sea ice. Together these instruments provide data from which a wide range of sea ice properties may be derived. We provide statistics on lead distribution and spacing, lead width and area, floe size and distance between floes, as well as ridge height, frequency and distribution. The goals of this study are to (i) identify unique statistics that can be used to describe the characteristics of specific ice regions, for example first-year/multi-year ice, diffuse ice edge/consolidated ice pack, and convergent

  16. Radiation effects in ice: New results

    International Nuclear Information System (INIS)

    Baragiola, R.A.; Fama, M.; Loeffler, M.J.; Raut, U.; Shi, J.

    2008-01-01

    Studies of radiation effects in ice are motivated by intrinsic interest and by applications in astronomy. Here we report on new and recent results on radiation effects induced by energetic ions in ice: amorphization of crystalline ice, compaction of microporous amorphous ice, electrostatic charging and dielectric breakdown and correlated structural/chemical changes in the irradiation of water-ammonia ices

  17. [Bacterial diversity within different sections of summer sea-ice samples from the Prydz Bay, Antarctica].

    Science.gov (United States)

    Ma, Jifei; Du, Zongjun; Luo, Wei; Yu, Yong; Zeng, Yixin; Chen, Bo; Li, Huirong

    2013-02-04

    In order to assess bacterial abundance and diversity within three different sections of summer sea-ice samples collected from the Prydz Bay, Antarctica. Fluorescence in situ hybridization was applied to determine the proportions of Bacteria in sea-ice. Bacterial community composition within sea ice was analyzed by 16S rRNA gene clone library construction. Correlation analysis was performed between the physicochemical parameters and the bacterial diversity and abundance within sea ice. The result of fluorescence in situ hybridization shows that bacteria were abundant in the bottom section, and the concentration of total organic carbon, total organic nitrogen and phosphate may be the main factors for bacterial abundance. In bacterial 16S rRNA gene libraries of sea-ice, nearly complete 16S rRNA gene sequences were grouped into three distinct lineages of Bacteria (gamma-Proteobacteria, alpha-Proteobacteria and Bacteroidetes). Most clone sequences were related to cultured bacterial isolates from the marine environment, arctic and Antarctic sea-ice with high similarity. The member of Bacteroidetes was not detected in the bottom section of sea-ice. The bacterial communities within sea-ice were little heterogeneous at the genus-level between different sections, and the concentration of NH4+ may cause this distribution. The number of bacteria was abundant in the bottom section of sea-ice. Gamma-proteobacteria was the dominant bacterial lineage in sea-ice.

  18. Interaction of ice sheets and climate during the past 800 000 years

    Science.gov (United States)

    Stap, L. B.; van de Wal, R. S. W.; de Boer, B.; Bintanja, R.; Lourens, L. J.

    2014-12-01

    During the Cenozoic, land ice and climate interacted on many different timescales. On long timescales, the effect of land ice on global climate and sea level is mainly set by large ice sheets in North America, Eurasia, Greenland and Antarctica. The climatic forcing of these ice sheets is largely determined by the meridional temperature profile resulting from radiation and greenhouse gas (GHG) forcing. As a response, the ice sheets cause an increase in albedo and surface elevation, which operates as a feedback in the climate system. To quantify the importance of these climate-land ice processes, a zonally averaged energy balance climate model is coupled to five one-dimensional ice sheet models, representing the major ice sheets. In this study, we focus on the transient simulation of the past 800 000 years, where a high-confidence CO2 record from ice core samples is used as input in combination with Milankovitch radiation changes. We obtain simulations of atmospheric temperature, ice volume and sea level that are in good agreement with recent proxy-data reconstructions. We examine long-term climate-ice-sheet interactions by a comparison of simulations with uncoupled and coupled ice sheets. We show that these interactions amplify global temperature anomalies by up to a factor of 2.6, and that they increase polar amplification by 94%. We demonstrate that, on these long timescales, the ice-albedo feedback has a larger and more global influence on the meridional atmospheric temperature profile than the surface-height-temperature feedback. Furthermore, we assess the influence of CO2 and insolation by performing runs with one or both of these variables held constant. We find that atmospheric temperature is controlled by a complex interaction of CO2 and insolation, and both variables serve as thresholds for northern hemispheric glaciation.

  19. Interaction of ice sheets and climate during the past 800 000 years

    Directory of Open Access Journals (Sweden)

    L. B. Stap

    2014-12-01

    Full Text Available During the Cenozoic, land ice and climate interacted on many different timescales. On long timescales, the effect of land ice on global climate and sea level is mainly set by large ice sheets in North America, Eurasia, Greenland and Antarctica. The climatic forcing of these ice sheets is largely determined by the meridional temperature profile resulting from radiation and greenhouse gas (GHG forcing. As a response, the ice sheets cause an increase in albedo and surface elevation, which operates as a feedback in the climate system. To quantify the importance of these climate–land ice processes, a zonally averaged energy balance climate model is coupled to five one-dimensional ice sheet models, representing the major ice sheets. In this study, we focus on the transient simulation of the past 800 000 years, where a high-confidence CO2 record from ice core samples is used as input in combination with Milankovitch radiation changes. We obtain simulations of atmospheric temperature, ice volume and sea level that are in good agreement with recent proxy-data reconstructions. We examine long-term climate–ice-sheet interactions by a comparison of simulations with uncoupled and coupled ice sheets. We show that these interactions amplify global temperature anomalies by up to a factor of 2.6, and that they increase polar amplification by 94%. We demonstrate that, on these long timescales, the ice-albedo feedback has a larger and more global influence on the meridional atmospheric temperature profile than the surface-height-temperature feedback. Furthermore, we assess the influence of CO2 and insolation by performing runs with one or both of these variables held constant. We find that atmospheric temperature is controlled by a complex interaction of CO2 and insolation, and both variables serve as thresholds for northern hemispheric glaciation.

  20. Modeling the heating and melting of sea ice through light absorption by microalgae

    Science.gov (United States)

    Zeebe, Richard E.; Eicken, Hajo; Robinson, Dale H.; Wolf-Gladrow, Dieter; Dieckmann, Gerhard S.

    1996-01-01

    In sea ice of polar regions, high concentrations of microalgae are observed during the spring. Algal standing stocks may attain peak values of over 300 mg chl a m-2 in the congelation ice habitat. As of yet, the effect of additional heating of sea ice through conversion of solar radiation into heat by algae has not been investigated in detail. Local effects, such as a decrease in albedo, increasing melt rates, and a decrease of the physical strength of ice sheets may occur. To investigate the effects of microalgae on the thermal regime of sea ice, a time-dependent, one-dimensional thermodynamic model of sea ice was coupled to a bio-optical model. A spectral one-stream model was employed to determine spectral attenuation by snow, sea ice, and microalgae. Beer's law was assumed to hold for every wavelength. Energy absorption was obtained by calculating the divergence of irradiance in every layer of the model (Δz = 1 cm). Changes in sea ice temperature profiles were calculated by solving the heat conduction equation with a finite difference scheme. Model results indicate that when algal biomass is concentrated at the bottom of congelation ice, melting of ice resulting from the additional conversion of solar radiation into heat may effectively destroy the algal habitat, thereby releasing algal biomass into the water column. An algal layer located in the top of the ice sheet induced a significant increase in sea ice temperature (ΔT > 0.3 K) for snow depths less than 5 cm and algal standing stocks higher than 150 mg chl a m-2. Furthermore, under these conditions, brine volume increased by 21% from 181 to 219 parts per thousand, which decreased the physical strength of the ice.

  1. Theoretical assessment of the potential to deduce microphysical characteristics of ice clouds from polarimetric radar measurements at 95 GHz; Theoretische Untersuchungen zur Ableitung mikrophysikalischer Parameter von Eiswolken aus polarimetrischen Radarmessungen bei 95 GHz

    Energy Technology Data Exchange (ETDEWEB)

    Lemke, H.M. [GKSS-Forschungszentrum Geesthacht GmbH (Germany). Inst. fuer Atmosphaerenphysik

    2000-07-01

    The potential of polarimetric radar measurements at 95 GHz to derive microphysical cloud characteristics is assessed. Scattering by atmospheric ice crystals is calculated applying the discrete dipole approximation (DDA) for single crystals of various shape, size, and orientation. The results are combined to acquire radar signals for collections of particles representing the radar volume. Expressing the particle size with respect to the radius of a volume equivalent sphere, the co-plar reflectivity is only slightly affected by particle shape variations. Thus, keeping the limitations of such an approach in mind, the simplified representation of crystals as spheres is applicable. On the other hand, the signal is strongly influenced by the particle size and the total ice water content. Polarimetric radar parameters like linear depolarisation ratio and differential reflectivity are almost independent of size and ice water content. They are predominantly affected by the crystal shape and orientation and therefore have a potential to deduce information about ice crystal habits. Unfortunately, to date such measurements are subject to technical restrictions. (orig.)

  2. Mass Balance of the Greenland Ice Sheet at High Elevations.

    Science.gov (United States)

    Thomas; Akins; Csatho; Fahnestock; Gogineni; Kim; Sonntag

    2000-07-21

    Comparison of ice discharge from higher elevation areas of the entire Greenland Ice Sheet with total snow accumulation gives estimates of ice thickening rates over the past few decades. On average, the region has been in balance, but with thickening of 21 centimeters per year in the southwest and thinning of 30 centimeters per year in the southeast. The north of the ice sheet shows less variability, with average thickening of 2 centimeters per year in the northeast and thinning of about 5 centimeters per year in the northwest. These results agree well with those from repeated altimeter surveys, except in the extreme south, where we find substantially higher rates of both thickening and thinning.

  3. Aero-thermal optimization of in-flight electro-thermal ice protection systems in transient de-icing mode

    International Nuclear Information System (INIS)

    Pourbagian, Mahdi; Habashi, Wagdi G.

    2015-01-01

    Highlights: • We introduce an efficient methodology for the optimization of a de-icing system. • We can replace the expensive CHT simulation by ROM without loosing much accuracy. • We propose different criteria affecting the energy usage and aerodynamic performance. • These criteria can significantly improve the performance of the de-icing system. - Abstract: Even if electro-thermal ice protection systems (IPS) consume less energy when operating in de-icing mode than in anti-icing mode, they still need to be optimized for energy usage. The optimization, however, should also take into account the effect of the de-icing system on the aerodynamic performance. The present work offers an optimization framework in which both thermal and aerodynamic viewpoints are taken into account in formulating various objective and constraint functions by considering the energy consumption, the thickness, the volume, the shape and the location of the accreted ice on the surface as the key parameters affecting the energy usage and the aerodynamic performance. The design variables include the power density and the activation time of the electric heating blankets. A derivative-free technique, called the mesh adaptive direct search (MADS) method, is used to carry out the optimization process, which would normally need a large number of unsteady conjugate heat transfer (CHT) calculations for the IPS simulation. To avoid such prohibitive computations, reduced-order modeling (ROM) is used to construct simplified low-dimensional CHT models. The approach is illustrated through several test cases, in which different combinations of objective and constraint functions, design variables and cycling sequence patterns are examined. In these test cases, the energy consumption is significantly reduced compared to the experiments by improving the spatial and temporal distribution of the thermal energy usage. The results show the benefits of the approach in bringing energy, safety and

  4. Impact of ice particle shape on short-wave radiative forcing: A case study for an arctic ice cloud

    International Nuclear Information System (INIS)

    Kahnert, Michael; Sandvik, Anne Dagrun; Biryulina, Marina; Stamnes, Jakob J.; Stamnes, Knut

    2008-01-01

    We used four different non-spherical particle models to compute optical properties of an arctic ice cloud and to simulate corresponding cloud radiative forcings and fluxes. One important finding is that differences in cloud forcing, downward flux at the surface, and absorbed flux in the atmosphere resulting from the use of the four different ice cloud particle models are comparable to differences in these quantities resulting from changing the surface albedo from 0.4 to 0.8, or by varying the ice water content (IWC) by a factor of 2. These findings show that the use of a suitable non-spherical ice cloud particle model is very important for a realistic assessment of the radiative impact of arctic ice clouds. The differences in radiative broadband fluxes predicted by the four different particle models were found to be caused mainly by differences in the optical depth and the asymmetry parameter. These two parameters were found to have nearly the same impact on the predicted cloud forcing. Computations were performed first by assuming a given vertical profile of the particle number density, then by assuming a given profile of the IWC. In both cases, the differences between the cloud radiative forcings computed with the four different non-spherical particle models were found to be of comparable magnitude. This finding shows that precise knowledge of ice particle number density or particle mass is not sufficient for accurate prediction of ice cloud radiative forcing. It is equally important to employ a non-spherical shape model that accurately reproduces the ice particle's dimension-to-volume ratio and its asymmetry parameter. The hexagonal column/plate model with air-bubble inclusions seems to offer the highest degree of flexibility

  5. First investigations of an ice core from Eisriesenwelt cave (Austria

    Directory of Open Access Journals (Sweden)

    B. May

    2011-02-01

    Full Text Available Investigations into the genesis and dynamical properties of cave ice are essential for assessing the climate significance of these underground glaciers. We drilled an ice core through a 7.1 m-thick ice body filling a large cavern of the dynamic ice cave Eisenriesenwelt (Austria. In addition to visual core inspections, quasi-continuous measurements at 2 cm resolution comprised particulate matter, stable water isotope (δ18O, δD and electrolytic conductivity profiles supplemented by specifically selected samples analyzed for tritium and radiocarbon. We found that recent ablation led to an almost complete loss of bomb-derived tritium removing any ice accumulated since, at least, the early fifties leaving the actual ice surface even below the natural tritium level. The small particulate organic masses rendered radiocarbon dating inconclusive, though a crude estimate gave a basal ice age in the order of several thousand years. The visual stratigraphy and all investigated parameters showed a clear dichotomy between the upper 2 m and the bottom 3 m of the core, which points to a substantial change in the ice formation process. Main features of the core comprise the changing appearance and composition of distinct cryocalcite layers, extremely low total ion content and a surprisingly high variability of the isotope signature. Co-isotope evaluation (δD versus δ18O of the core in comparison with data from precipitation and karst spring water clearly indicate that ice formation is governed by (slow freezing of dripping water.

  6. Development of Job’s tears ice cream recipes with carrot juice and pumpkin paste

    OpenAIRE

    Wiwat Wangcharoen

    2011-01-01

    Carrot juice and pumpkin paste were used as ingredients in Job’s tears ice cream. Carrot juice or pumpkin paste added at 50% was equally preferred by 100 consumers compared to the original Job’s tears ice cream. The new types of ice cream were lower in antioxidant capacity and higher in total phenolic content but could still be considered as potential antioxidant products. Purchase intent was significantly increased (p

  7. Diffuse scattering in Ih ice

    International Nuclear Information System (INIS)

    Wehinger, Björn; Krisch, Michael; Bosak, Alexeï; Chernyshov, Dmitry; Bulat, Sergey; Ezhov, Victor

    2014-01-01

    Single crystals of ice Ih, extracted from the subglacial Lake Vostok accretion ice layer (3621 m depth) were investigated by means of diffuse x-ray scattering and inelastic x-ray scattering. The diffuse scattering was identified as mainly inelastic and rationalized in the frame of ab initio calculations for the ordered ice XI approximant. Together with Monte-Carlo modelling, our data allowed reconsidering previously available neutron diffuse scattering data of heavy ice as the sum of thermal diffuse scattering and static disorder contribution. (paper)

  8. Modelling the Antarctic Ice Sheet

    DEFF Research Database (Denmark)

    Pedersen, Jens Olaf Pepke; Holm, A.

    2015-01-01

    to sea level high stands during past interglacial periods. A number of AIS models have been developed and applied to try to understand the workings of the AIS and to form a robust basis for future projections of the AIS contribution to sea level change. The recent DCESS (Danish Center for Earth System......The Antarctic ice sheet is a major player in the Earth’s climate system and is by far the largest depository of fresh water on the planet. Ice stored in the Antarctic ice sheet (AIS) contains enough water to raise sea level by about 58 m, and ice loss from Antarctica contributed significantly...

  9. How might the North American ice sheet influence the northwestern Eurasian climate?

    Science.gov (United States)

    Beghin, P.; Charbit, S.; Dumas, C.; Kageyama, M.; Ritz, C.

    2015-10-01

    It is now widely acknowledged that past Northern Hemisphere ice sheets covering Canada and northern Europe at the Last Glacial Maximum (LGM) exerted a strong influence on climate by causing changes in atmospheric and oceanic circulations. In turn, these changes may have impacted the development of the ice sheets themselves through a combination of different feedback mechanisms. The present study is designed to investigate the potential impact of the North American ice sheet on the surface mass balance (SMB) of the Eurasian ice sheet driven by simulated changes in the past glacial atmospheric circulation. Using the LMDZ5 atmospheric circulation model, we carried out 12 experiments under constant LGM conditions for insolation, greenhouse gases and ocean. In these experiments, the Eurasian ice sheet is removed. The 12 experiments differ in the North American ice-sheet topography, ranging from a white and flat (present-day topography) ice sheet to a full-size LGM ice sheet. This experimental design allows the albedo and the topographic impacts of the North American ice sheet onto the climate to be disentangled. The results are compared to our baseline experiment where both the North American and the Eurasian ice sheets have been removed. In summer, the sole albedo effect of the American ice sheet modifies the pattern of planetary waves with respect to the no-ice-sheet case, resulting in a cooling of the northwestern Eurasian region. By contrast, the atmospheric circulation changes induced by the topography of the North American ice sheet lead to a strong decrease of this cooling. In winter, the Scandinavian and the Barents-Kara regions respond differently to the American ice-sheet albedo effect: in response to atmospheric circulation changes, Scandinavia becomes warmer and total precipitation is more abundant, whereas the Barents-Kara area becomes cooler with a decrease of convective processes, causing a decrease of total precipitation. The gradual increase of the

  10. Does Arctic sea ice reduction foster shelf-basin exchange?

    Science.gov (United States)

    Ivanov, Vladimir; Watanabe, Eiji

    2013-12-01

    The recent shift in Arctic ice conditions from prevailing multi-year ice to first-year ice will presumably intensify fall-winter sea ice freezing and the associated salt flux to the underlying water column. Here, we conduct a dual modeling study whose results suggest that the predicted catastrophic consequences for the global thermohaline circulation (THC), as a result of the disappearance of Arctic sea ice, may not necessarily occur. In a warmer climate, the substantial fraction of dense water feeding the Greenland-Scotland overflow may form on Arctic shelves and cascade to the deep basin, thus replenishing dense water, which currently forms through open ocean convection in the sub-Arctic seas. We have used a simplified model for estimating how increased ice production influences shelf-basin exchange associated with dense water cascading. We have carried out case studies in two regions of the Arctic Ocean where cascading was observed in the past. The baseline range of buoyancy-forcing derived from the columnar ice formation was calculated as part of a 30-year experiment of the pan-Arctic coupled ice-ocean general circulation model (GCM). The GCM results indicate that mechanical sea ice divergence associated with lateral advection accounts for a significant part of the interannual variations in sea ice thermal production in the coastal polynya regions. This forcing was then rectified by taking into account sub-grid processes and used in a regional model with analytically prescribed bottom topography and vertical stratification in order to examine specific cascading conditions in the Pacific and Atlantic sectors of the Arctic Ocean. Our results demonstrate that the consequences of enhanced ice formation depend on geographical location and shelf-basin bathymetry. In the Pacific sector, strong density stratification in slope waters impedes noticeable deepening of shelf-origin water, even for the strongest forcing applied. In the Atlantic sector, a 1.5x increase of

  11. Structural incorporation of MgCl2 into ice VII at room temperature

    Science.gov (United States)

    Watanabe, Mao; Komatsu, Kazuki; Noritake, Fumiya; Kagi, Hiroyuki

    2017-05-01

    Raman spectra and X-ray diffraction patterns were obtained from 1:100 and 1:200 \\text{MgCl}2:\\text{H}2\\text{O} solutions (in molar ratio) at pressures up to 6 GPa using diamond anvil cells (DACs) and compared with those of pure water. The O-H stretching band from ice VII crystallized from the 1:200 solution was approximately 10 cm-1 higher than that of pure ice VII. The phase boundaries between ice VII and VIII crystallized from the MgCl2 solutions at 4 GPa were 2 K lower than those of pure ice VII and VIII. These observations indicate that ice VII incorporates MgCl2 into its structure. The unit cell volumes of ice VII crystallized from pure water and the two solutions coincided with each other within the experimental error, and salt incorporation was not detectable from the cell volume. Possible configurations of ion substitution and excess volume of ice VIII were simulated on the basis of density functional theory (DFT) calculations.