Comparison of heat transfer in liquid and slush nitrogen by numerical simulation of cooling rates for French straws used for sperm cryopreservation.

PubMed

Sansinena, M; Santos, M V; Zaritzky, N; Chirife, J

2012-05-01

Slush nitrogen (SN(2)) is a mixture of solid nitrogen and liquid nitrogen, with an average temperature of -207 °C. To investigate whether plunging a French plastic straw (commonly used for sperm cryopreservation) in SN(2) substantially increases cooling rates with respect to liquid nitrogen (LN(2)), a numerical simulation of the heat conduction equation with convective boundary condition was used to predict cooling rates. Calculations performed using heat transfer coefficients in the range of film boiling confirmed the main benefit of plunging a straw in slush over LN(2) did not arise from their temperature difference (-207 vs. -196 °C), but rather from an increase in the external heat transfer coefficient. Numerical simulations using high heat transfer (h) coefficients (assumed to prevail in SN(2)) suggested that plunging in SN(2) would increase cooling rates of French straw. This increase of cooling rates was attributed to a less or null film boiling responsible for low heat transfer coefficients in liquid nitrogen when the straw is placed in the solid-liquid mixture or slush. In addition, predicted cooling rates of French straws in SN(2) tended to level-off for high h values, suggesting heat transfer was dictated by heat conduction within the liquid filled plastic straw. Copyright © 2012 Elsevier Inc. All rights reserved.

Blackbody Cavity for Calibrations at 200 to 273 K

NASA Technical Reports Server (NTRS)

Howell, Dane; Ryan, Robert; Ryan, Jim; Henderson, Doug; Clayton, Larry

2004-01-01

A laboratory blackbody cavity has been designed and built for calibrating infrared radiometers used to measure radiant temperatures in the range from about 200 to about 273 K. In this below-room-temperature range, scattering of background infrared radiation from room-temperature surfaces could, potentially, contribute significantly to the spectral radiance of the blackbody cavity, thereby contributing a significant error to the radiant temperature used as the calibration value. The present blackbody cavity is of an established type in which multiple reflections from a combination of conical and cylindrical black-coated walls are exploited to obtain an effective emissivity greater than the emissivity value of the coating material on a flat exposed surface. The coating material in this case is a flat black paint that has an emissivity of approximately of 0.91 in the thermal spectral range and was selected over other, higher-emissivity materials because of its ability to withstand thermal cycling. We found many black coatings cracked and flaked after thermal cycling due to differences in the coefficient of expansion differences. On the basis of theoretical calculations, the effective emissivity is expected to approach 0.999. The cylindrical/conical shell enclosing the cavity is machined from copper, which is chosen for its high thermal conductivity. In use, the shell is oriented vertically, open end facing up, and inserted in a Dewar flask filled with isopropyl alcohol/dry-ice slush. A flange at the open end of the shell is supported by a thermally insulating ring on the lip of the Dewar flask. The slush cools the shell (and thus the black-body cavity) to the desired temperature. Typically, the slush starts at a temperature of about 194 K. The slush is stirred and warmed by bubbling dry air or nitrogen through it, thereby gradually increasing the temperature through the aforementioned calibration range during an interval of several hours. The temperature of the slush is monitored by use of a precise thermocouple probe.

An explanation for why it is difficult to form slush nitrogen from liquid nitrogen used previously for this purpose.

PubMed

Baker, Michael J; Denton, Travis T; Herr, Charles

2013-02-01

Slush nitrogen (SN) is used to avoid the Leidenfrost effect, which is problematic when using liquid nitrogen (LN). Slush nitrogen's usefulness has been demonstrated by its requirement for the successful cryopreservation of insect embryos. To convert LN to SN, typically, the pressure above a Dewar of LN is reduced, using a vacuum pump in a sealed system until conversion occurs. It has been observed that LN from a fresh tank will readily produce SN; however, repeated use of the same LN results in the inability to form SN in subsequent trials. The current experiments were designed to identify the cause of this phenomenon. The hypothesis is that gaseous oxygen from the surrounding, ambient air condenses and mixes with the LN to form a mixture with a lower freezing point and; therefore, prevents the formation of SN. The hypothesis was tested and found to be true. Copyright © 2012. Published by Elsevier Inc.

Slush Hydrogen Technology Program

NASA Technical Reports Server (NTRS)

Cady, Edwin C.

1994-01-01

A slush hydrogen (SH2) technology facility (STF) was designed, fabricated, and assembled by a contractor team of McDonnell Douglas Aerospace (MDA), Martin Marietta Aerospace Group (MMAG), and Air Products and Chemicals, Inc. (APCI). The STF consists of a slush generator which uses the freeze-thaw production process, a vacuum subsystem, a test tank which simulates the NASP vehicle, a triple point hydrogen receiver tank, a transfer subsystem, a sample bottle, a pressurization system, and a complete instrumentation and control subsystem. The STF was fabricated, checked-out, and made ready for testing under this contract. The actual SH2 testing was performed under the NASP consortium following NASP teaming. Pre-STF testing verified SH2 production methods, validated special SH2 instrumentation, and performed limited SH2 pressurization and expulsion tests which demonstrated the need for gaseous helium pre-pressurized of SH2 to control pressure collapse. The STF represents cutting-edge technology development by an effective Government-Industry team under very tight cost and schedule constraints.

Robotic partial nephrectomy with intracorporeal renal hypothermia using ice slush.

PubMed

Kaouk, Jihad H; Samarasekera, Dinesh; Krishnan, Jayram; Autorino, Riccardo; Acka, Oktay; Brando, Luis Felipe; Laydner, Humberto; Zargar, Homayoun

2014-09-01

To outline our technique for intracorporeal cooling with ice slush during robotic partial nephrectomy (RPN), with real-time parenchymal temperature monitoring. Eleven consecutive patients with enhancing solid renal masses suitable for treatment with RPN between September 2013 and January 2014 were included in the analysis. Institutional review board approval and informed consent were obtained. Preoperative patient characteristics, intraoperative surgical parameters including patient body temperature and ipsilateral kidney temperature with real-time monitoring, and short-term functional outcomes were analyzed. Median age was 55 years (range, 39-75 years) and American Society of Anesthesiologists score was 3 (range, 2-4). Median tumor size was 4 cm (range, 2.3-7.1) and RENAL nephrometry score was 9 (range, 5-11). One patient had a solitary kidney. During cooling, the lowest median renal parenchymal temperature was 17.05°C (range, 11°C-26°C) and cold ischemia time was 27.17 minutes (range, 18-49 minutes). Median time to latest postoperative estimated glomerular filtration rate was 12 days (range, 2-30 days). Median glomerular filtration rate preservation was 81% (range, 47.9%-126%). There was one positive margin. There were no postoperative complications, and no patients experienced a prolonged ileus. The limitations of this study include a small number of patients and short-term follow-up. RPN with renal hypothermia using intracorporeal ice slush is technically feasible. Our simplified method of introducing the ice slush was free of complications and highly reproducible. The use of a needle temperature probe allowed us to monitor in real time cooling of the renal parenchyma. Copyright © 2014 Elsevier Inc. All rights reserved.

Influence of heat transfer rates on pressurization of liquid/slush hydrogen propellant tanks

NASA Technical Reports Server (NTRS)

Sasmal, G. P.; Hochstein, J. I.; Hardy, T. L.

1993-01-01

A multi-dimensional computational model of the pressurization process in liquid/slush hydrogen tank is developed and used to study the influence of heat flux rates at the ullage boundaries on the process. The new model computes these rates and performs an energy balance for the tank wall whereas previous multi-dimensional models required a priori specification of the boundary heat flux rates. Analyses of both liquid hydrogen and slush hydrogen pressurization were performed to expose differences between the two processes. Graphical displays are presented to establish the dependence of pressurization time, pressurant mass required, and other parameters of interest on ullage boundary heat flux rates and pressurant mass flow rate. Detailed velocity fields and temperature distributions are presented for selected cases to further illuminate the details of the pressurization process. It is demonstrated that ullage boundary heat flux rates do significantly effect the pressurization process and that minimizing heat loss from the ullage and maximizing pressurant flow rate minimizes the mass of pressurant gas required to pressurize the tank. It is further demonstrated that proper dimensionless scaling of pressure and time permit all the pressure histories examined during this study to be displayed as a single curve.

Ground penetrating radar detection of subsnow slush on ice-covered lakes in interior Alaska

NASA Astrophysics Data System (ADS)

Gusmeroli, A.; Grosse, G.

2012-12-01

Lakes are abundant throughout the pan-Arctic region. For many of these lakes ice cover lasts for up to two thirds of the year. The frozen cover allows human access to these lakes, which are therefore used for many subsistence and recreational activities, including water harvesting, fishing, and skiing. Safe traveling condition onto lakes may be compromised, however, when, after significant snowfall, the weight of the snow acts on the ice and causes liquid water to spill through weak spots and overflow at the snow-ice interface. Since visual detection of subsnow slush is almost impossible our understanding on overflow processes is still very limited and geophysical methods that allow water and slush detection are desirable. In this study we demonstrate that a commercially available, lightweight 1 GHz, ground penetrating radar system can detect and map extent and intensity of overflow. The strength of radar reflections from wet snow-ice interfaces are at least twice as much in strength than returns from dry snow-ice interface. The presence of overflow also affects the quality of radar returns from the base of the lake ice. During dry conditions we were able to profile ice thickness of up to 1 m, conversely, we did not retrieve any ice-water returns in areas affected by overflow.

Sea-ice eukaryotes of the Gulf of Finland, Baltic Sea, and evidence for herbivory on weakly shade-adapted ice algae.

PubMed

Majaneva, Markus; Blomster, Jaanika; Müller, Susann; Autio, Riitta; Majaneva, Sanna; Hyytiäinen, Kirsi; Nagai, Satoshi; Rintala, Janne-Markus

2017-02-01

To determine community composition and physiological status of early spring sea-ice organisms, we collected sea-ice, slush and under-ice water samples from the Baltic Sea. We combined light microscopy, HPLC pigment analysis and pyrosequencing, and related the biomass and physiological status of sea-ice algae with the protistan community composition in a new way in the area. In terms of biomass, centric diatoms including a distinct Melosira arctica bloom in the upper intermediate section of the fast ice, dinoflagellates, euglenoids and the cyanobacterium Aphanizomenon sp. predominated in the sea-ice sections and unidentified flagellates in the slush. Based on pigment analyses, the ice-algal communities showed no adjusted photosynthetic pigment pools throughout the sea ice, and the bottom-ice communities were not shade-adapted. The sea ice included more characteristic phototrophic taxa (49%) than did slush (18%) and under-ice water (37%). Cercozoans and ciliates were the richest taxon groups, and the differences among the communities arose mainly from the various phagotrophic protistan taxa inhabiting the communities. The presence of pheophytin a coincided with an elevated ciliate biomass and read abundance in the drift ice and with a high Eurytemora affinis read abundance in the pack ice, indicating that ciliates and Eurytemora affinis were grazing on algae. Copyright © 2016 Elsevier GmbH. All rights reserved.

14 CFR 25.1091 - Air induction.

Code of Federal Regulations, 2011 CFR

2011-01-01

... turbine engine powered airplanes and airplanes incorporating auxiliary power units— (1) There must be...) The airplane must be designed to prevent water or slush on the runway, taxiway, or other airport...

14 CFR 25.1091 - Air induction.

Code of Federal Regulations, 2010 CFR

2010-01-01

... turbine engine powered airplanes and airplanes incorporating auxiliary power units— (1) There must be...) The airplane must be designed to prevent water or slush on the runway, taxiway, or other airport...

14 CFR 25.1091 - Air induction.

Code of Federal Regulations, 2013 CFR

2013-01-01

... turbine engine powered airplanes and airplanes incorporating auxiliary power units— (1) There must be...) The airplane must be designed to prevent water or slush on the runway, taxiway, or other airport...

14 CFR 25.1091 - Air induction.

Code of Federal Regulations, 2012 CFR

2012-01-01

... turbine engine powered airplanes and airplanes incorporating auxiliary power units— (1) There must be...) The airplane must be designed to prevent water or slush on the runway, taxiway, or other airport...

14 CFR 25.1091 - Air induction.

Code of Federal Regulations, 2014 CFR

2014-01-01

... turbine engine powered airplanes and airplanes incorporating auxiliary power units— (1) There must be...) The airplane must be designed to prevent water or slush on the runway, taxiway, or other airport...

14 CFR 23.1091 - Air induction system.

Code of Federal Regulations, 2013 CFR

2013-01-01

... indicate to the flight crew when it is not closed. (c) For turbine engine powered airplanes— (1) There must... designed to prevent water or slush on the runway, taxiway, or other airport operating surfaces from being...

14 CFR 23.1091 - Air induction system.

Code of Federal Regulations, 2012 CFR

2012-01-01

... indicate to the flight crew when it is not closed. (c) For turbine engine powered airplanes— (1) There must... designed to prevent water or slush on the runway, taxiway, or other airport operating surfaces from being...

14 CFR 23.1091 - Air induction system.

Code of Federal Regulations, 2014 CFR

2014-01-01

... indicate to the flight crew when it is not closed. (c) For turbine engine powered airplanes— (1) There must... designed to prevent water or slush on the runway, taxiway, or other airport operating surfaces from being...

14 CFR 23.1091 - Air induction system.

Code of Federal Regulations, 2011 CFR

2011-01-01

... indicate to the flight crew when it is not closed. (c) For turbine engine powered airplanes— (1) There must... designed to prevent water or slush on the runway, taxiway, or other airport operating surfaces from being...

14 CFR 135.4 - Applicability of rules for eligible on-demand operations.

Code of Federal Regulations, 2010 CFR

2010-01-01

... minimum of 500 hours. (ii) For multi-engine turbine-powered fixed-wing and powered-lift aircraft, the... runway to be used has water, snow, slush, ice, or similar contamination that may adversely affect...

30 CFR 57.9362 - Protection of signalmen.

Code of Federal Regulations, 2010 CFR

2010-07-01

... MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Loading, Hauling, and Dumping Safety Devices, Provisions, and Procedures for Roadways, Railroads, and Loading and Dumping Sites § 57.9362 Protection of signalmen. Signalmen used during slushing operations underground...

Sea Language Our Heritage.

ERIC Educational Resources Information Center

Heitzmann, Wm. Ray

1982-01-01

Reviews several references focusing on words and phrases in the American language which have nautical origins (sailing, whaling, navigation, ship-building and others) and have since lost their nautical connections. Also includes examples from the references such as "slush fund", "posh", and "windfall." (JN)

Feasibility study of a low-energy gamma ray system for measuring quantity and flow rate of slush hydrogen

NASA Technical Reports Server (NTRS)

Singh, Jag J.; Shen, Chih-Ping; Sprinkle, Danny R.

1992-01-01

As part of a study to demonstrate the suitability of an X-ray or gamma ray probe for monitoring the quality and flow rate of slush hydrogen, mass attenuation coefficients for Cd-109 X- and gamma radiation in five chemical compounds were measured. The Ag-109 K rays were used for water and acetic acid, whereas E3 transition from the first excited state at 87.7 keV in Ag-109 provided the probe radiation for bromobenzene, alpha (exp 2) chloroisodurene, and cetyl bromide. Measurements were made for a single phase (gas, liquid, solid) as well as mixed phases (liquid plus solid) in all cases. It was shown that the mass attenuation coefficient for the selected radiations is independent of the phase of the test fluids or phase ratios in the case of mixed phase fluids. Described here are the procedure and the results for the five fluid systems investigated.

Heat Accumulation: An Easy Way Anticipate the Flowering of Southern Pines

Treesearch

William D. Boyer

1978-01-01

Accumulation of degree-day heat sums accounts for most of the year-to-year variation in dates of peak pollen shed by slush (Pinus etliottii Engelm.), longleaf (P. palustris Mill.), loblolly (P. taeda L.), and shortleaf (P. echinata Mill.) pines. During 19 years of observation for...

The Separate and Cumulative Effects of TBI and PTSD on Cognitive Function and Emotional Control

DTIC Science & Technology

2009-04-01

CADDIE 80. SHY 80. BABY 80. HATRED 81. BOMB 81. TENANT 81. BUILDING 81. JOYFUL 81. SLIME 82. WMD 82. NFL 82. TOWER...82. SONG 82. FRAUD 83. BASRA 83. PARTISAN 83. HORSE 83. PLEASURE 83. MOLD 84. GUN 84. REDECORATE 84. SLUSH 84. COMEDY

Computational modeling of the pressurization process in a NASP vehicle propellant tank experimental simulation

NASA Technical Reports Server (NTRS)

Sasmal, G. P.; Hochstein, J. I.; Wendl, M. C.; Hardy, T. L.

1991-01-01

A multidimensional computational model of the pressurization process in a slush hydrogen propellant storage tank was developed and its accuracy evaluated by comparison to experimental data measured for a 5 ft diameter spherical tank. The fluid mechanic, thermodynamic, and heat transfer processes within the ullage are represented by a finite-volume model. The model was shown to be in reasonable agreement with the experiment data. A parameter study was undertaken to examine the dependence of the pressurization process on initial ullage temperature distribution and pressurant mass flow rate. It is shown that for a given heat flux rate at the ullage boundary, the pressurization process is nearly independent of initial temperature distribution. Significant differences were identified between the ullage temperature and velocity fields predicted for pressurization of slush and those predicted for pressurization of liquid hydrogen. A simplified model of the pressurization process was constructed in search of a dimensionless characterization of the pressurization process. It is shown that the relationship derived from this simplified model collapses all of the pressure history data generated during this study into a single curve.

Can "Word Choices" Compromise a Woman's Career?

ERIC Educational Resources Information Center

Mendoza, Sylvia

2011-01-01

A letter of recommendation can catapult a woman into the next phase of the interview process for a particular job--or land her in the slush pile. Word choice in describing this female candidate can make or break her career. Letters of recommendation--especially when a reference's word choice paints a negative, less than stellar picture of the…

Stop Internal Resource Slush Fund Act

THOMAS, 113th Congress

Rep. Turner, Michael R. [R-OH-10

2013-06-12

House - 06/12/2013 Referred to the Committee on Ways and Means, and in addition to the Committees on Oversight and Government Reform, and Appropriations, for a period to be subsequently determined by the Speaker, in each case for consideration of such provisions as fall within the... (All Actions) Tracker: This bill has the status IntroducedHere are the steps for Status of Legislation:

Quantification of net annual C input in terrestrial ecosystems of the Italian Peninsula under different land-uses

USDA-ARS?s Scientific Manuscript database

Soil organic matter (SOM) is a very important compartment of the biosphere: it represents the largest dynamic carbon (C) pool where the C is stored for the longest time period. Root inputs, as exudates and root slush, represent a major, where not the largest, annual contribution to soil C input. Roo...

A System Approach to Navy Medical Education and Training. Appendix 6. Pharmacy Technician.

DTIC Science & Technology

1974-08-31

lz PREPARE BUFFER SOLUTIONS 13 ICOMPUTE AMOUNTS OF INGREDIENTS FOR CCMPOUNDING/PREPARING IPHARMACEUTICALS 14 IWEIGH/MEASURE CHEMICALS 15 ICHECK ...DOSAGE OF DIAGNOSTIC PHARMACEUTICAL, E.G. BSP DYE II 19 1PREPARE C02 SLUSH 20 PREPARE PATCH TEST SOLUTION USING PATIENTOS SUSPECTED ALLERGENS 21 ICHECK ...PRESCRIPTIONS FOR INCOMPATABILITY/IDIOSYNCRACIES OF ICONCURRENTLY PRESCRIBED MEDICATIONS 22 ICHECK PRESCRIPTIONS FOR COMPLETENESSE.Go DRUG, IDOSEFORMSIG

A Laboratory Study of the Effect of Frost Flowers on C Band Radar Backscatter from Sea Ice

NASA Technical Reports Server (NTRS)

Nghiem, S. V.; Martin, S.; Perovich, D. K.; Kwok, R.; Drucker, R.; Gow, A. J.

1997-01-01

C band images of Arctic sea ice taken by the ERS 1 synthetic aperture radar show transitory regions of enhanced radar backscatter from young sea ice. Published field observations associate this increase with frost flower growth and the capture of blowing snow by the flowers. To investigate the first part of this phenomenon, we carried out a laboratory experiment on the response of C band radar backscatter to frost flowers growing on the surface of newly formed saline ice. The experiment took place in a 5 m by 7 m by 1.2 m deep saline water pool located in a two-story indoor refrigerated facility at the Cold Regions Research and Engineering Laboratory. Sodium chloride ice was grown in this pool at an air temperature of -28 C. The frost flowers first appeared on the ice surface as dendrites and then changed to needles as the ice sheet grew thicker and the surface temperatures became colder. The frost flowers reached to a height of 10-15 mm, and beneath each cluster of frost flowers a slush layer formed to a thickness of approximately 4 mm. Far-field radar measurements of the backscatter from the ice were made at incident angles from 20 to 40 deg and at approximately 6-hour intervals throughout the 3-day period of the experiment. A backscatter minimum occurred early in the flower growth at the time coincident with an abrupt doubling in the ice surface salinity. Once the full flower coverage was achieved, we removed first the crystal flowers and then the slush layer from the ice surface. The results for these cases show that the crystals have little impact on the backscatter, while the underlying slush patches yield a backscatter increase of 3-5 dB over that of bare ice. The laboratory results suggest that this relative backscatter increase of approximately 5 dB can be used as an index to mark the full area coverage of frost flowers.

A Laboratory Study of the Effect of Frost Flowers on C Band Radar Backscatter from Sea Ice

NASA Technical Reports Server (NTRS)

Nghiem, S. V.; Martin, S.; Perovich, D. K.; Kwok, R.; Drucker, R.; Gow, A. J.

1997-01-01

C band images of Arctic sea ice taken by the ERS 1 synthetic aperture radar show transitory regions of enhanced radar backscatter from young sea ice. Published field observations associate this increase with frost flower growth and the capture of blowing snow by the flowers. To investigate the first part of this phenomenon, we carried out a laboratory experiment on the response of C band radar backscatter to frost flowers growing on the surface of newly formed saline ice. The experiment took place in a 5 m by 7 m by 1.2 m deep saline water pool located in a two-story indoor refrigerated facility at the Cold Regions Research and Engineering Laboratory. Sodium chloride ice was grown in this pool at an air temperature of -28 C. The frost flowers first appeared on the ice surface as dendrites and then changed to needles as the ice sheet grew thicker and the surface temperatures became colder. The frost flowers reached to a height of 10-15 mm, and beneath each cluster of frost flowers a slush layer formed to a thickness of approximately 4 mm. Far-field radar measurements of the backscatter from the ice were made at incident angles from 20 C to 40 C and at approximately 6-hour intervals throughout the 3-day period of the experiment. A backscatter minimum occurred early in the flower growth at the time coincident with an abrupt doubling in the ice surface salinity. Once the full flower coverage was achieved, we removed first the crystal flowers and then the slush layer from the ice surface. The results for these cases show that the crystals have little impact on the backscatter, while the underlying slush patches yield a backscatter increase of 3-5 dB over that o f bare ice. The laboratory results suggest that this relative backscatter increase of approximately 5 dB can be used as an index to mark the full areal coverage of frost flowers.

Sarsen Stones of Stonehenge: How and by what route were the stones transported? What is the significance of their markings?

PubMed

Hill, P A

1961-04-21

A route via Lockeridge and the Avon Valley, involving a slide down the chalk escarpment, is postulated for the sarsen stones of Stonehenge. The transportation problem would have been greatly simplified if the stones had been relayed from point to point over snow or slush during successive winters. Markings on the stones hitherto undescribed are interpreted.

Demonstrate a Low Biochemical Oxygen Demand Aircraft Deicing Fluid

DTIC Science & Technology

2013-03-01

Technologies International, LTD for collection and recycling of fluids. Spent fluid, diluted with any water, slush or snow removed from the aircraft or...Resistance Unmated only – some failures Voltage Withstand Testing Unmated only – some failures Plastic Windows Crazing Effect Pass The testing did result...At Joint Base McGuire-Dix-Lakehurst, however, waste PG is currently collected with a vacuum truck and recycled . Factors such as the market demand

Demonstrate a Low Biochemical Oxygen Demand Aircraft Deicing Fluid

DTIC Science & Technology

2013-03-04

Technologies International, LTD for collection and recycling of fluids. Spent fluid, diluted with any water, slush or snow removed from the aircraft or...Resistance Unmated only – some failures Voltage Withstand Testing Unmated only – some failures Plastic Windows Crazing Effect Pass The testing did result...At Joint Base McGuire-Dix-Lakehurst, however, waste PG is currently collected with a vacuum truck and recycled . Factors such as the market demand

Conceptual study of space plane powered by hypersonic airbreathing propulsion system

NASA Astrophysics Data System (ADS)

Maita, Masataka; Ohkami, Yoshiaki; Yamanaka, Tatsuo; Mori, Takashige

1990-10-01

The paper describes the investigations of aerospace plane concept, conducted by the National Aerospace Laboratory (NAL) of Japan, with particular attention given to a concept which integrates a scram/liquid air cycle engine (LACE) hypersonic propulsion system fueling with slush hydrogen. The key requirements in achieving the space plane using scram/LACE propulsion system are described along with the mission requirements and the vehicle characteristics. Typical outputs of SSTO analysis are presented.

Technical accomplishments of the NASA Lewis Research Center, 1989

NASA Technical Reports Server (NTRS)

1990-01-01

Topics addressed include: high-temperature composite materials; structural mechanics; fatigue life prediction for composite materials; internal computational fluid mechanics; instrumentation and controls; electronics; stirling engines; aeropropulsion and space propulsion programs, including a study of slush hydrogen; space power for use in the space station, in the Mars rover, and other applications; thermal management; plasma and radiation; cryogenic fluid management in space; microgravity physics; combustion in reduced gravity; test facilities and resources.

Monitoring and forecasting local landslide hazard in the area of Longyearbyen, Svalbard - early progress and experiences from the Autumn 2016 events

NASA Astrophysics Data System (ADS)

Wang, Thea; Krøgli, Ingeborg; Boje, Søren; Colleuille, Hervé

2017-04-01

Since 2013 the Norwegian Water Resources and Energy Directorate (NVE) has operated a landslide early warning system (LEWS) for mainland Norway. The Svalbard islands, situated 800 km north of the Norwegian mainland, and 1200 km from the North Pole, are not part of the conventional early warning service. However, following the fatal snow avalanche event 19 Dec. 2015 in the settlement of Longyearbyen (78° north latitude), local authorities and the NVE have initiated monitoring of the hydro-meteorological conditions for the area of Longyearbyen, as an extraordinary precaution. Two operational forecasting teams from the NVE; the snow avalanche and the landslide hazard forecasters, perform hazard assessment related to snow avalanches, slush flows, debris flows, shallow slides and local flooding. This abstract will focus on recent experiences made by the landslide hazard team during the autumn 2016 landslide events, caused by a record setting wet and warm summer and autumn of 2016. The general concept of the Norwegian LEWS is based on frequency intervals of extreme hydro-meteorological conditions. This general concept has been transposed to the Longyearbyen area. Although the climate is considerably colder and drier than mainland Norway, experiences so far are positive and seem useful to the local authorities. Initially, the landslide hazard evaluation was intended to consider only slush flow hazard during the snow covered season. However, due to the extraordinary warm and wet summer and autumn 2016, the landslide hazard forecasters unexpectedly had to issue warnings for the local authorities due to increased risk of shallow landslides and debris flows. This was done in close cooperation with the Norwegian Meteorological Institute, who provided weather forecasts from the recently developed weather prediction model, AROME-Arctic. Two examples, from 14-15 Oct and 8-9 Nov 2016, will be given to demonstrate how the landslide hazard assessment for the Longyearbyen area is carried out. Several aspects contrast hazard monitoring and forecasting on the mainland, such as the challenges that transpire with sparse observations of hydrometeorologial variables, landslide inventories and hydrological simulations. Particular challenges that are faced on Svalbard, are the even greater remoteness of the settlements and the strong effect permafrost has on the soil structure. The planned development for improving the monitoring of slush avalanches and landslide hazards in the Longyearbyen area will also be presented.

Slush Hydrogen (SLH2) technology development for application to the National Aerospace Plane (NASP)

NASA Technical Reports Server (NTRS)

Dewitt, Richard L.; Hardy, Terry L.; Whalen, Margaret V.; Richter, G. Paul

1989-01-01

The National Aerospace Plane (NASP) program is giving us the opportunity to reach new unique answers in a number of engineering categories. The answers are considered enhancing technology or enabling technology. Airframe materials and densified propellants are examples of enabling technology. The National Aeronautics and Space Administration's Lewis Research Center has the task of providing the technology data which will be used as the basis to decide if slush hydrogen (SLH2) will be the fuel of choice for the NASP. The objectives of this NASA Lewis program are: (1) to provide, where possible, verified numerical models of fluid production, storage, transfer, and feed systems, and (2) to provide verified design criteria for other engineered aspects of SLH2 systems germane to a NASP. This program is a multiyear multimillion dollar effort. The present pursuit of the above listed objectives is multidimensional, covers a range of problem areas, works these to different levels of depth, and takes advantage of the resources available in private industry, academia, and the U.S. Government. The NASA Lewis overall program plan is summarized. The initial implementation of the plan will be unfolded and the present level of efforts in each of the resource areas will be discussed. Results already in hand will be pointed out. A description of additionally planned near-term experimental and analytical work is described.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lara-Curzio, Edgar; Rios, Orlando; Marquez-Rossy, Andres Emilio

ORNL collaborated with Faurecia Interior Systems to investigate the feasibility of developing a thermomagnetic preventive maintenance program for nickel tooling used in powder slush molding. It was found that thermal treatments at temperatures greater than 500°C can anneal strain hardening in nickel tooling and a range of temperatures and times for effective thermal annealing were identified. It was also observed that magnetic fields applied during thermal annealing do not alter the kinetics of strain hardening annealing. The results obtained in this investigation provide a foundation for establishing a preventive maintenance program for nickel tooling.

Grooved Terrain on Ganymede: A Galileo-based Synthesis

NASA Technical Reports Server (NTRS)

Pappalardo, Robert T.; Collins, Geoffrey C.; Head, James W.; Moore, Jeffrey M.; Schenk, Paul M.

2003-01-01

Swaths of bright "grooved terrain" (sulci) on Ganymede are 10s to 100s of kilometers wide and cross-cut the older dark terrain, forming an intricate patchwork across 2/3 of Ganymede's surface. The view of grooved terrain developed from Voyager images is that bright cells are broad graben infilled by extrusion of relatively clean (silicate-poor) liquid water, warm ice, or icy slush, and then extended and faulted. Galileo imaging has greatly improved understanding of the emplacement history and geological implications of grooved terrain, supporting a rift-like model for its formation.

Slush-like polar structures in single-crystal relaxors

NASA Astrophysics Data System (ADS)

Takenaka, Hiroyuki; Grinberg, Ilya; Liu, Shi; Rappe, Andrew M.

2017-06-01

Despite more than 50 years of investigation, it is still unclear how the underlying structure of relaxor ferroelectrics gives rise to their defining properties, such as ultrahigh piezoelectric coefficients, high permittivity over a broad temperature range, diffuse phase transitions, strong frequency dependence in dielectric response, and phonon anomalies. The model of polar nanoregions inside a non-polar matrix has been widely used to describe the structure of relaxor ferroelectrics. However, the lack of precise knowledge about the shapes, growth and dipole patterns of polar nanoregions has led to the characterization of relaxors as “hopeless messes”, and no predictive model for relaxor behaviour is currently available. Here we use molecular dynamics simulations of the prototypical Pb(Mg1/3,Nb2/3)O3-PbTiO3 relaxor material to examine its structure and the spatial and temporal polarization correlations. Our simulations show that the unusual properties of relaxors stem from the presence of a multi-domain state with extremely small domain sizes (2-10 nanometres), and no non-polar matrix, owing to the local dynamics. We find that polar structures in the multi-domain state in relaxors are analogous to those of the slush state of water. The multi-domain structure of relaxors that is revealed by our molecular dynamics simulations is consistent with recent experimental diffuse scattering results and indicates that relaxors have a high density of low-angle domain walls. This insight explains the recently discovered classes of relaxors that cannot be described by the polar nanoregion model, and provides guidance for the design and synthesis of new relaxor materials.

Frost flowers on young Arctic sea ice: The climatic, chemical, and microbial significance of an emerging ice type

NASA Astrophysics Data System (ADS)

Barber, D. G.; Ehn, J. K.; Pućko, M.; Rysgaard, S.; Deming, J. W.; Bowman, J. S.; Papakyriakou, T.; Galley, R. J.; Søgaard, D. H.

2014-10-01

Ongoing changes in Arctic sea ice are increasing the spatial and temporal range of young sea ice types over which frost flowers can occur, yet the significance of frost flowers to ocean-sea ice-atmosphere exchange processes remains poorly understood. Frost flowers form when moisture from seawater becomes available to a cold atmosphere and surface winds are low, allowing for supersaturation of the near-surface boundary layer. Ice grown in a pond cut in young ice at the mouth of Young Sound, NE Greenland, in March 2012, showed that expanding frost flower clusters began forming as soon as the ice formed. The new ice and frost flowers dramatically changed the radiative and thermal environment. The frost flowers were about 5°C colder than the brine surface, with an approximately linear temperature gradient from their base to their upper tips. Salinity and δ18O values indicated that frost flowers primarily originated from the surface brine skim. Ikaite crystals were observed to form within an hour in both frost flowers and the thin pond ice. Average ikaite concentrations were 1013 µmol kg-1 in frost flowers and 1061 µmol kg-1 in the surface slush layer. Chamber flux measurements confirmed an efflux of CO2 at the brine-wetted sea ice surface, in line with expectations from the brine chemistry. Bacteria concentrations generally increased with salinity in frost flowers and the surface slush layer. Bacterial densities and taxa indicated that a selective process occurred at the ice surface and confirmed the general pattern of primary oceanic origin versus negligible atmospheric deposition.

NASP - Waveriders in a hypersonic sky.

NASA Astrophysics Data System (ADS)

Baker, David

1993-01-01

A development history is presented for the hydrogen-fueled, airbreathing (scramjet) engine-propelled National Aerospace Plane (NASP), which will be able to cruise endoatmospherically at hypersopnic speeds or rise exoatmospherically, by converting to rocket power, to LEO. Attention is given to the technology-development and configuration-validation services that the X-30 project will render the far larger NASP vehicle; the configurational and propulsion system factors in question encompass the use of 'slush' hydrogen fuel, the integration of engine inlets into the aircraft forebody and exhaust nozzles into the afterbody, and the conversion from turbojet or rocket propulsion to scramjet mode and back.

Liquid air cycle engines

NASA Technical Reports Server (NTRS)

Rosevear, Jerry

1992-01-01

Given here is a definition of Liquid Air Cycle Engines (LACE) and existing relevant technologies. Heat exchanger design and fabrication techniques, the handling of liquid hydrogen to achieve the greatest heat sink capabilities, and air decontamination to prevent heat exchanger fouling are discussed. It was concluded that technology needs to be extended in the areas of design and fabrication of heat exchangers to improve reliability along with weight and volume reductions. Catalysts need to be improved so that conversion can be achieved with lower quantities and lower volumes. Packaging studies need to be investigated both analytically and experimentally. Recycling with slush hydrogen needs further evaluation with experimental testing.

Cryogenic hydrogen-induced air-liquefaction technologies for combined-cycle propulsion applications

NASA Technical Reports Server (NTRS)

Escher, William J. D.

1992-01-01

Given here is a technical assessment of the realization of cryogenic hydrogen induced air liquefaction technologies in a prospective onboard aerospace vehicle process setting. The technical findings related to the status of air liquefaction technologies are reviewed. Compact lightweight cryogenic heat exchangers, heat exchanger atmospheric constituent fouling alleviation measures, para/ortho-hydrogen shift-conversion catalysts, cryogenic air compressors and liquid air pumps, hydrogen recycling using slush hydrogen as a heat sink, liquid hydrogen/liquid air rocket-type combustion devices, and technically related engine concepts are discussed. Much of the LACE work is related to aerospaceplane propulsion concepts that were developed in the 1960's. Emphasis is placed on the Liquid Air Cycle Engine (LACE).

Cryopreservation of feline oocytes by vitrification using commercial kits and slush nitrogen technique.

PubMed

Fernandez-Gonzalez, L; Jewgenow, K

2017-04-01

Assisted reproductive techniques are a valuable tool for conservation breeding of endangered species. Cryopreservation methods are the basis of gamete banks, supporting genetic diversity preservation. Unfortunately, cryopreservation of feline oocytes is still considered an experimental technique. The aim of this study was to compare two commercial kits, with our protocol for vitrification of cat oocytes (IZW), which comprises a three-step method with ethylene glycol, DMSO, fetal calf serum, trehalose and Ficoll PM-70. Furthermore, we applied slush nitrogen (SN 2 ) for ultra-rapid freezing to improve survival rates. Cumulus-oocyte complexes were collected from domestic cat ovaries by slicing and vitrified at immature stage using Cryotop as storage device. Vit Kit ® Freeze/Thaw (n = 89) showed the lowest maturation percentage obtained after warming (10.1%). A significant difference in maturation percentage of oocytes was found between Kitazato ® kit (38.7%, n = 137) and IZW protocol (24.5%, n = 143). The cleavage after ICSI of warmed and matured oocytes (20.7% and 28.6%, respectively) and the morula percentage (18. 2% and 22.5%, respectively), however, did not reveal any significant difference between the two methods. Application of SN 2 did not result in any improvement of oocytes' cryopreservation. Maturation percentage of the oocytes vitrified by IZW method with SN 2 (n = 144) decreased until 6.1%, without any cleavage after fertilization. For Kitazato ® (n = 62), only 17.7% were able to undergo maturation and cleavage percentage dropped to 18.2%, not reaching morula stage. These data demonstrate that feline oocytes can be vitrified either by our IZW method or by commercial Kitazato ® kit, but the use of SN 2 is improving neither maturation nor cleavage percentages when combined with these procedures. © 2016 Blackwell Verlag GmbH.

Thermal evolutions of two kinds of melt pond with different salinity

NASA Astrophysics Data System (ADS)

Kim, Joo-Hong; Wilkinson, Jeremy; Moon, Woosok; Hwang, Byongjun; Granskog, Mats

2016-04-01

Melt ponds are water pools on sea ice. Their formation reduces ice surface albedo and alter surface energy balance, by which the ice melting and freezing processes are regulated. Thus, better understanding of their radiative characteristics has been vital to improve the simulation of melting/freezing of sea ice in numerical models. A melt pond would preserve nearly fresh water if it formed on multi-year ice and no flooding of sea water occurred, whereas a melt pond would contain more salty water if it formed on thinner and porous first-year ice, if there were an inflow of sea water by streams or cracks. One would expect that the fluid dynamic/thermodynamic properties (e.g., turbulence, stability, etc.) of pond water are influenced by the salinity, so that the response of pond water to any heat input (e.g., shortwave radiation) would be different. Therefore, better understanding of the salinity-dependent thermal evolution also has significant potential to improve the numerical simulation of the sea ice melting/freezing response to radiative thermal forcing. To observe and understand the salinity-dependent thermal evolution, two ice mass balance buoys (IMBs) were deployed in two kinds (fresh and salty) of melt pond on a same ice floe on 13 August 2015 during Araon Arctic cruise. The thermistor chain, extending from the air through the pond and ice into the sea water, was deployed through a drilled borehole inside the pond. Besides, the IMBs were also accompanied with three broadband solar radiation sensors (two (up and down) in the air over melt pond and one upward-looking under sea ice) to measure the net shortwave radiation at the pond surface and the penetrating solar radiation through ice. Also, the web camera was installed to observe any updates in the conditions of equipment and surrounding environment (e.g., weather, surface state, etc.). On the date of deployment, the fresh pond had salinity of 2.3 psu, light blue color, lots of slush ice particles which increased opacity, and under-pond ice thickness of 219 cm, whereas the salty pond had salinity of 20 psu, dark blue color, only transparent water, and under-pond ice thickness of 100 cm. Temporal evolutions of mean water temperature of the two ponds are contrasted and showed that the fresh pond had about 1degC warmer temperature than the salty pond. The existence of slush ice particles in the pond seems to be responsible for this temperature difference. Multiple scattering by slush ice particles could lead to more absorption of shortwave radiation. A comparison of vertical profiles of water temperature shows that there existed an internal maximum heating layer in the fresh pond. Possibly, this profile might indicate the the below layer unstable, which might have efficient thermal propagation to the ice surface. On the other hand, the vertical temperature profile of the salty pond had internal thermocline near the pond bottom, but so that the upper heating may not efficiently propagate downward to the ice surface.

Observations of the freeze/thaw performance of lithium fluoride by motion picture photography

NASA Technical Reports Server (NTRS)

Jaworske, D. A.; Perry, W. D.

1991-01-01

To gain direct observation of the molten salt phase change, a novel containerless technique was developed where the high surface tension of lithium fluoride was used to suspend a bead of the molten salt inside a specially designed wire cage. By varying the current passing through the wire, the cage also served as a variable heat source. In this way, the freeze/thaw performance of the lithium fluoride could be photographed by motion picture photography without the influence of container walls. The motion picture photography of the lithium fluoride sample revealed several zones during the phase change, a solid zone and a liquid zone, as expected, and a slush zone that was predicted by thermal analysis modeling.

Safety Issues with Hydrogen as a Vehicle Fuel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cadwallader, Lee Charles; Herring, James Stephen

1999-10-01

This report is an initial effort to identify and evaluate safety issues associated with the use of hydrogen as a vehicle fuel in automobiles. Several forms of hydrogen have been considered: gas, liquid, slush, and hydrides. The safety issues have been discussed, beginning with properties of hydrogen and the phenomenology of hydrogen combustion. Safety-related operating experiences with hydrogen vehicles have been summarized to identify concerns that must be addressed in future design activities and to support probabilistic risk assessment. Also, applicable codes, standards, and regulations pertaining to hydrogen usage and refueling have been identified and are briefly discussed. This reportmore » serves as a safety foundation for any future hydrogen safety work, such as a safety analysis or a probabilistic risk assessment.« less

Safety Issues with Hydrogen as a Vehicle Fuel

DOE Office of Scientific and Technical Information (OSTI.GOV)

L. C. Cadwallader; J. S. Herring

1999-09-01

This report is an initial effort to identify and evaluate safety issues associated with the use of hydrogen as a vehicle fuel in automobiles. Several forms of hydrogen have been considered: gas, liquid, slush, and hydrides. The safety issues have been discussed, beginning with properties of hydrogen and the phenomenology of hydrogen combustion. Safety-related operating experiences with hydrogen vehicles have been summarized to identify concerns that must be addressed in future design activities and to support probabilistic risk assessment. Also, applicable codes, standards, and regulations pertaining to hydrogen usage and refueling have been identified and are briefly discussed. This reportmore » serves as a safety foundation for any future hydrogen safety work, such as a safety analysis or a probabilistic risk assessment.« less

Cryogenic hydrogen-induced air liquefaction technologies

NASA Technical Reports Server (NTRS)

Escher, William J. D.

1990-01-01

Extensively utilizing a special advanced airbreathing propulsion archives database, as well as direct contacts with individuals who were active in the field in previous years, a technical assessment of cryogenic hydrogen-induced air liquefaction, as a prospective onboard aerospace vehicle process, was performed and documented. The resulting assessment report is summarized. Technical findings are presented relating the status of air liquefaction technology, both as a singular technical area, and also that of a cluster of collateral technical areas including: compact lightweight cryogenic heat exchangers; heat exchanger atmospheric constituents fouling alleviation; para/ortho hydrogen shift conversion catalysts; hydrogen turbine expanders, cryogenic air compressors and liquid air pumps; hydrogen recycling using slush hydrogen as heat sink; liquid hydrogen/liquid air rocket-type combustion devices; air collection and enrichment systems (ACES); and technically related engine concepts.

Mineral precipitation in north slope aufeis

NASA Technical Reports Server (NTRS)

Hall, D. K.

1978-01-01

The Canning and Shaviovik river aufeis fields were studied on the ground and with aircraft data. Powdered calcium carbonate (CaCO3) patches, a few cm in thickness, were found in discrete locations on both aufeis fields. This is indicative of chemical weathering of limestone bedrock which is known to underlie much of the eastern arctic coastal plain of Alaska. Spring or river water which remains unfrozen throughout much of the winter carries CaCO3 in solution; as the river ice freezes more deeply the CaCO3 in solution is forced upwards through cracks in the river ice. Upon exposure to the cold air CaCO3 is excluded as the water freezes, forming successive layers during aufeis growth. In the melt season CaCO3, slush/powder accumulates in patches on top of the ice as the aufeis melts downward.

Cryogenic hydrogen-induced air-liquefaction technologies

NASA Technical Reports Server (NTRS)

Escher, William J. D.

1990-01-01

Extensive use of a special advanced airbreathing propulsion archives data base, as well as direct contacts with individuals who were active in the field in previous years, a technical assessment of cryogenic hydrogen induced air liquefaction, as a prospective onboard aerospace vehicle process, was performed and documented in 1986. The resulting assessment report is summarized. Technical findings relating the status of air liquefaction technology are presented both as a singular technical area, and also as that of a cluster of collateral technical areas including: Compact lightweight cryogenic heat exchangers; Heat exchanger atmospheric constituents fouling alleviation; Para/ortho hydrogen shift conversion catalysts; Hydrogen turbine expanders, cryogenic air compressors and liquid air pumps; Hydrogen recycling using slush hydrogen as heat sinks; Liquid hydrogen/liquid air rocket type combustion devices; Air Collection and Enrichment System (ACES); and Technically related engine concepts.

Safety in new uses of hydrogen energy

NASA Astrophysics Data System (ADS)

Knowlton, R. E.

The paper presents the results of two projects of the Canadian Hydrogen Safety Committee: one concerned with the safety of hydrogen as a ground transportation fuel (with emphasis on LH2), and the other concerned with finding new uses for hydrogen energy. Bulk storage distribution, retail storage, refueling, and in-vehicle use of LH2 are discussed together with the hazards of LH2 use. Applications discussed include: (1) small submarines (with 3-11 crew members) for under-ice operations and for maintenance of installations; (2) mine vehicles; (3) the use of radiant heat from H2-O2 flames to disperse fog by radiant heat transfer; and (4) the use of slush hydrogen both as a fuel and for superconducting motors and magnets. The latter concept could become the basis for a high-speed passenger transport system with linear motors and magnetic levitation.

Large scale production of densified hydrogen to the triple point and below

NASA Astrophysics Data System (ADS)

Swanger, A. M.; Notardonato, W. U.; E Fesmire, J.; Jumper, K. M.; Johnson, W. L.; Tomsik, T. M.

2017-12-01

Recent demonstration of advanced liquid hydrogen storage techniques using Integrated Refrigeration and Storage technology at NASA Kennedy Space Center led to the production of large quantities of densified liquid and slush hydrogen in a 125,000 L tank. Production of densified hydrogen was performed at three different liquid levels and LH2 temperatures were measured by twenty silicon diode temperature sensors. Overall densification performance of the system is explored, and solid mass fractions are calculated. Experimental data reveal hydrogen temperatures dropped well below the triple point during testing, and were continuing to trend downward prior to system shutdown. Sub-triple point temperatures were seen to evolve in a time dependent manner along the length of the horizontal, cylindrical vessel. The phenomenon, observed at two fill levels, is detailed herein. The implications of using IRAS for energy storage, propellant densification, and future cryofuel systems are discussed.

Passive microwave mapping of ice thickness. Final Report. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Apinis, J. J.; Peake, W. H.

1976-01-01

Basic calculations are presented for evaluating the feasibility of a scanning microwave radiometer system for mapping the thickness of lake ice. An analytical model for the apparent brightness temperature as a function of ice thickness has been developed, and elaborated to include such variables as galactic and atmospheric noise, aspect angle, polarization, temperature gradient in the ice, the presence of transition layers such as snow, slush, and water, increased loss due to air inclusions in the ice layer, and the presence of multiple ice thicknesses within the antenna footprint. It was found that brightness temperature measurements at six or seven frequencies in the range of 0.4 to 0.7 GHz were required to obtain unambiquous thickness estimates. A number of data processing methods were examined. The effects of antenna beamwidth, scanning rate, receiver bandwidth, noise figure, and integration time were studied.

Large Scale Production of Densified Hydrogen to the Triple Point and Below

NASA Technical Reports Server (NTRS)

Swanger, A. M.; Notardonato, W. U.; Fesmire, J. E.; Jumper, K. M.; Johnson, W. L.; Tomsik, T. M.

2017-01-01

Recent demonstration of advanced liquid hydrogen storage techniques using Integrated Refrigeration and Storage technology at NASA Kennedy Space Center led to the production of large quantities of densified liquid and slush hydrogen in a 125,000 L tank. Production of densified hydrogen was performed at three different liquid levels and LH2 temperatures were measured by twenty silicon diode temperature sensors. Overall densification performance of the system is explored, and solid mass fractions are calculated. Experimental data reveal hydrogen temperatures dropped well below the triple point during testing, and were continuing to trend downward prior to system shutdown. Sub-triple point temperatures were seen to evolve in a time dependent manner along the length of the horizontal, cylindrical vessel. The phenomenon, observed at two fill levels, is detailed herein. The implications of using IRAS for energy storage, propellant densification, and future cryofuel systems are discussed.

Comparison of radar backscatter from Antarctic and Arctic sea ice

NASA Technical Reports Server (NTRS)

Hosseinmostafa, R.; Lytle, V.

1992-01-01

Two ship-based step-frequency radars, one at C-band (5.3 GHz) and one at Ku-band (13.9 GHz), measured backscatter from ice in the Weddell Sea. Most of the backscatter data were from first-year (FY) and second-year (SY) ice at the ice stations where the ship was stationary and detailed snow and ice characterizations were performed. The presence of a slush layer at the snow-ice interface masks the distinction between FY and SY ice in the Weddell Sea, whereas in the Arctic the separation is quite distinct. The effect of snow-covered ice on backscattering coefficients (sigma0) from the Weddell Sea region indicates that surface scattering is the dominant factor. Measured sigma0 values were compared with Kirchhoff and regression-analysis models. The Weibull power-density function was used to fit the measured backscattering coefficients at 45 deg.

Dynamics of suspended sediment plumes in Lake Ontario

NASA Technical Reports Server (NTRS)

Pluhowski, E. J. (Principal Investigator)

1974-01-01

The author has identified the following significant results. Although turbidity plumes in Lake Ontario are usually not visible during the winter, meteorologic and hydrologic events may combine to ensure their detection. The clearly defined Niagara River plume of January 25, 1974, was the result of turbid water entering the river at its source near the eastern end of Lake Erie. A persistent southwest wind mild temperature resulted in a pile-up of ice free but turbid water at the source of the Niagara River where the highly colored water entered the river. Upon discharge into Lake Ontario, the Niagara River water appears several shades lighter in tone than the ambient lake water. On February 12, 1974, eastward moving ice floes along the Ontario shoreline were forced to move around the hydraulic barrier created by the Niagara River jet. As a result the Niagara River plume was clearly portrayed by a halo-like band of slush ice borne by wind-driven nearshore currents.

Safety Standard for Hydrogen and Hydrogen Systems: Guidelines for Hydrogen System Design, Materials Selection, Operations, Storage and Transportation. Revision

NASA Technical Reports Server (NTRS)

1997-01-01

The NASA Safety Standard, which establishes a uniform process for hydrogen system design, materials selection, operation, storage, and transportation, is presented. The guidelines include suggestions for safely storing, handling, and using hydrogen in gaseous (GH2), liquid (LH2), or slush (SLH2) form whether used as a propellant or non-propellant. The handbook contains 9 chapters detailing properties and hazards, facility design, design of components, materials compatibility, detection, and transportation. Chapter 10 serves as a reference and the appendices contained therein include: assessment examples; scaling laws, explosions, blast effects, and fragmentation; codes, standards, and NASA directives; and relief devices along with a list of tables and figures, abbreviations, a glossary and an index for ease of use. The intent of the handbook is to provide enough information that it can be used alone, but at the same time, reference data sources that can provide much more detail if required.

Can natural variability trigger effects on fish and fish habitat as defined in environment Canada's metal mining environmental effects monitoring program?

PubMed

Mackey, Robin; Rees, Cassandra; Wells, Kelly; Pham, Samantha; England, Kent

2013-01-01

The Metal Mining Effluent Regulations (MMER) took effect in 2002 and require most metal mining operations in Canada to complete environmental effects monitoring (EEM) programs. An "effect" under the MMER EEM program is considered any positive or negative statistically significant difference in fish population, fish usability, or benthic invertebrate community EEM-defined endpoints. Two consecutive studies with the same statistically significant differences trigger more intensive monitoring, including the characterization of extent and magnitude and investigation of cause. Standard EEM study designs do not require multiple reference areas or preexposure sampling, thus results and conclusions about mine effects are highly contingent on the selection of a near perfect reference area and are at risk of falsely labeling natural variation as mine related "effects." A case study was completed to characterize the natural variability in EEM-defined endpoints during preexposure or baseline conditions. This involved completing a typical EEM study in future reference and exposure lakes surrounding a proposed uranium (U) mine in northern Saskatchewan, Canada. Moon Lake was sampled as the future exposure area as it is currently proposed to receive effluent from the U mine. Two reference areas were used: Slush Lake for both the fish population and benthic invertebrate community surveys and Lake C as a second reference area for the benthic invertebrate community survey. Moon Lake, Slush Lake, and Lake C are located in the same drainage basin in close proximity to one another. All 3 lakes contained similar water quality, fish communities, aquatic habitat, and a sediment composition largely comprised of fine-textured particles. The fish population survey consisted of a nonlethal northern pike (Esox lucius) and a lethal yellow perch (Perca flavescens) survey. A comparison of the 5 benthic invertebrate community effect endpoints, 4 nonlethal northern pike population effect endpoints, and 10 lethal yellow perch effect endpoints resulted in the observation of several statistically significant differences at the future exposure area relative to the reference area and/or areas. When the data from 2 reference areas assessed for the benthic invertebrate community survey were pooled, no significant differences in effect endpoints were observed. These results demonstrate weaknesses in the definition of an "effect" used by the MMER EEM program and in the use of a single reference area. Determination of the ecological significance of statistical differences identified as part of EEM programs conducted during the operational period should consider preexisting (background) natural variability between reference and exposure areas. Copyright © 2012 SETAC.

Potential low cost, safe, high efficiency propellant for future space program

NASA Astrophysics Data System (ADS)

Zhou, D.

2005-03-01

Mixtures of nanometer or micrometer sized carbon powder suspended in hydrogen and methane/hydrogen mixtures are proposed as candidates for low cost, high efficiency propellants for future space programs. While liquid hydrogen has low weight and high heat of combustion per unit mass, because of the low mass density the heat of combustion per unit volume is low, and the liquid hydrogen storage container must be large. The proposed propellants can produce higher gross heat combustion with small volume with trade off of some weight increase. Liquid hydrogen can serve as the fluid component of the propellant in the mixtures and thus used by current rocket engine designs. For example, for the same volume a mixture of 5% methane and 95% hydrogen, can lead to an increase in the gross heat of combustion by about 10% and an increase in the Isp (specific impulse) by 21% compared to a pure liquid hydrogen propellant. At liquid hydrogen temperatures of 20.3 K, methane will be in solid state, and must be formed as fine granules (or slush) to satisfy the requirement of liquid propellant engines.

Polarimetric Signatures of Sea Ice. Part 1; Theoretical Model

NASA Technical Reports Server (NTRS)

Nghiem, S. V.; Kwok, R.; Yueh, S. H.; Drinkwater, M. R.

1995-01-01

Physical, structural, and electromagnetic properties and interrelating processes in sea ice are used to develop a composite model for polarimetric backscattering signatures of sea ice. Physical properties of sea ice constituents such as ice, brine, air, and salt are presented in terms of their effects on electromagnetic wave interactions. Sea ice structure and geometry of scatterers are related to wave propagation, attenuation, and scattering. Temperature and salinity, which are determining factors for the thermodynamic phase distribution in sea ice, are consistently used to derive both effective permittivities and polarimetric scattering coefficients. Polarimetric signatures of sea ice depend on crystal sizes and brine volumes, which are affected by ice growth rates. Desalination by brine expulsion, drainage, or other mechanisms modifies wave penetration and scattering. Sea ice signatures are further complicated by surface conditions such as rough interfaces, hummocks, snow cover, brine skim, or slush layer. Based on the same set of geophysical parameters characterizing sea ice, a composite model is developed to calculate effective permittivities and backscattering covariance matrices at microwave frequencies for interpretation of sea ice polarimetric signatures.

An outbreak of hepatitis A in recently vaccinated students from ice snacks made from contaminated well water.

PubMed

Zhang, L J; Wang, X J; Bai, J M; Fang, G; Liu, L G; Zhang, Y; Fontaine, R E

2009-03-01

On 30 May 2006, township S in Sichuan Province, China, reported an outbreak of hepatitis A (HA) in students who had recently received HA vaccine. The concern was raised that the vaccine had caused the outbreak. We attempted to identify the source of infection and mode of transmission. A HA case was defined as onset of jaundice or anorexia since 1 April 2006 with a twofold elevation of alanine aminotransferase (ALT) and anti-HA virus-IgM in a resident of or visitor to the township. Exposures to vaccine and snacks of 90 case-students to those of 107 control-students were compared. Thirty-four per cent of cases ate ice slush compared to 4.7% of controls (OR 4.1), and 51% of cases ate snow cones compared to 17% of controls (OR 8.3). The ice snacks were made with well water. HA virus RNA was detected by reverse transcription-polymerase chain reaction from patients' blood and well water. Untreated well water poses important dangers to the public in areas where piped, potable water is available.

Large Scale Production of Densified Hydrogen Using Integrated Refrigeration and Storage

NASA Technical Reports Server (NTRS)

Notardonato, William U.; Swanger, Adam Michael; Jumper, Kevin M.; Fesmire, James E.; Tomsik, Thomas M.; Johnson, Wesley L.

2017-01-01

Recent demonstration of advanced liquid hydrogen storage techniques using Integrated Refrigeration and Storage (IRAS) technology at NASA Kennedy Space Center led to the production of large quantities of solid densified liquid and slush hydrogen in a 125,000 L tank. Production of densified hydrogen was performed at three different liquid levels and LH2 temperatures were measured by twenty silicon diode temperature sensors. System energy balances and solid mass fractions are calculated. Experimental data reveal hydrogen temperatures dropped well below the triple point during testing (up to 1 K), and were continuing to trend downward prior to system shutdown. Sub-triple point temperatures were seen to evolve in a time dependent manner along the length of the horizontal, cylindrical vessel. Twenty silicon diode temperature sensors were recorded over approximately one month for testing at two different fill levels (33 67). The phenomenon, observed at both two fill levels, is described and presented detailed and explained herein., and The implications of using IRAS for energy storage, propellant densification, and future cryofuel systems are discussed.

Distribution of collagens type V and VI in the normal human alveolar mucosa: an immunoelectronmicroscopic study using ultrathin frozen sections.

PubMed

Rabanus, J P; Gelderblom, H R; Schuppan, D; Becker, J

1991-05-01

The ultrastructural localization of collagens type V and VI in normal human gingival mucosa was investigated by immunoelectron microscopy. Twenty biopsies were fixed in dimethylsuberimidate and shock-frozen in slush nitrogen. Collagen type V was mainly located to meshworks of uniform nonstriated microfibrils of 12 to 20 nm width, which preferentially appeared in larger spaces between cross-striated major collagen fibrils. Occasionally single microfibrils of collagen type V fanned out from the ends of major collagen fibrils, which may indicate a role as a core fibril. Collagen type V was not found in the subepithelial basement membrane and the immediately adjacent stroma. Collagen type VI was detected in a loose reticular network of unbanded microfilaments that were morphologically distinguishable by knoblike protrusions every 100-110 nm. These microfilaments were found in the vicinity, but not as an intrinsic component, of the subepithelial basement membrane. Single filaments of collagen type VI filaments appeared to form bridges between neighboring cross-striated major collagen fibrils, suggesting an interconnecting role for this collagen type. The method presented appears to be excellently suited to study the normal and pathological supramolecular organization of the oral extracellular matrix.

Evaluation of on-board hydrogen storage methods f or high-speed aircraft

NASA Technical Reports Server (NTRS)

Akyurtlu, Ates; Akyurtlu, Jale F.

1991-01-01

Hydrogen is the fuel of choice for hypersonic vehicles. Its main disadvantage is its low liquid and solid density. This increases the vehicle volume and hence the drag losses during atmospheric flight. In addition, the dry mass of the vehicle is larger due to larger vehicle structure and fuel tankage. Therefore it is very desirable to find a fuel system with smaller fuel storage requirements without deteriorating the vehicle performance substantially. To evaluate various candidate fuel systems, they were first screened thermodynamically with respect to their energy content and cooling capacities. To evaluate the vehicle performance with different fuel systems, a simple computer model is developed to compute the vehicle parameters such as the vehicle volume, dry mass, effective specific impulse, and payload capacity. The results indicate that if the payload capacity (or the gross lift-off mass) is the most important criterion, only slush hydrogen and liquid hydrogen - liquid methane gel shows better performance than the liquid hydrogen vehicle. If all the advantages of a smaller vehicle are considered and a more accurate mass analysis can be performed, other systems using endothermic fuels such as cyclohexane, and some boranes may prove to be worthy of further consideration.

The effects of cloud inhomogeneities upon radiative fluxes, and the supply of a cloud truth validation dataset

NASA Technical Reports Server (NTRS)

Welch, Ronald M.

1996-01-01

The ASTER polar cloud mask algorithm is currently under development. Several classification techniques have been developed and implemented. The merits and accuracy of each are being examined. The classification techniques under investigation include fuzzy logic, hierarchical neural network, and a pairwise histogram comparison scheme based on sample histograms called the Paired Histogram Method. Scene adaptive methods also are being investigated as a means to improve classifier performance. The feature, arctan of Band 4 and Band 5, and the Band 2 vs. Band 4 feature space are key to separating frozen water (e.g., ice/snow, slush/wet ice, etc.) from cloud over frozen water, and land from cloud over land, respectively. A total of 82 Landsat TM circumpolar scenes are being used as a basis for algorithm development and testing. Numerous spectral features are being tested and include the 7 basic Landsat TM bands, in addition to ratios, differences, arctans, and normalized differences of each combination of bands. A technique for deriving cloud base and top height is developed. It uses 2-D cross correlation between a cloud edge and its corresponding shadow to determine the displacement of the cloud from its shadow. The height is then determined from this displacement, the solar zenith angle, and the sensor viewing angle.

Europa's Active Surface

NASA Technical Reports Server (NTRS)

1996-01-01

A newly discovered impact crater can be seen just right of the center of this image of Jupiter's moon Europa returned by NASA's Galileo spacecraft camera. The crater is about 30 kilometers (18.5 miles) in diameter. The impact excavated into Europa's icy crust, throwing debris (seen as whitish material) across the surrounding terrain. Also visible is a dark band, named Belus Linea, extending east-west across the image. This type of feature, which scientists call a 'triple band,' is characterized by a bright stripe down the middle. The outer margins of this and other triple bands are diffuse, suggesting that the dark material was put there as a result of possible geyser-like activity which shot gas and rocky debris from Europa's interior. The curving 'X' pattern seen in the lower left corner of the image appears to represent fracturing of the icy crust and infilling by slush which froze in place. The crater is centered at about 2 degrees north latitude by 239 degrees west longitude. The image was taken from a distance of 156,000 kilometers (about 96,300 miles) on June 27, 1996, during Galileo's first orbit around Jupiter. The area shown is 860 by 700 kilometers (530 by 430 miles), or about the size of Oregon and Washington combined. The Galileo mission is managed by NASA's Jet Propulsion Laboratory.

Sensitivity of Runway Occupancy Time (ROT) to Various Rollout and Turnoff (ROTO) Factors. Volume 1

NASA Technical Reports Server (NTRS)

Goldthorpe, S. H.

1997-01-01

The Terminal Area Productivity (TAP) research program was initiated by NASA to increase the airport capacity for transport aircraft operations. One element of the research program is called Low Visibility Landing and Surface Operations (LVLASO). A goal of the LVLASO research is to develop transport aircraft technologies which reduce Runway Occupancy Time (ROT) so that it does not become the limiting factor in the terminal area operations that determine the capacity of a runway. Under LVLASO, the objective of this study was to determine the sensitivity of ROT to various factors associated with the Rollout and Turnoff (ROTO) operation for transport aircraft. The following operational factors were studied and are listed in the order of decreasing ROT sensitivity: ice/flood runway surface condition, exit entrance ground speed, number of exits, high-speed exit locations and spacing, aircraft type, touchdown ground speed standard deviation, reverse thrust and braking method, accurate exit prediction capability, maximum reverse thrust availability, spiral-arc vs. circle-arc exit geometry, dry/slush/wet/snow runway surface condition, maximum allowed deceleration, auto asymmetric braking on exit, do not stow reverse thrust before the exit, touchdown longitudinal location standard deviation, flap setting, anti-skid efficiency, crosswind conditions, stopping on the exit and touchdown lateral offset.

Efficiency and temperature dependence of water removal by membrane dryers

NASA Technical Reports Server (NTRS)

Leckrone, K. J.; Hayes, J. M.

1997-01-01

The vapor pressure of water in equilibrium with sorption sites within a Nafion membrane is given by log P(WN) = -3580/T + 10.01, where P(WN) is expressed in Torr and T is the membrane temperature, in kelvin. The efficiency of dryers based on selective permeation of water through Nafion can thus be enhanced by cooling the membrane. Residual water in effluents exceeds equilibrium levels if insufficient time is allowed for water to diffuse to the membrane surface as gas passes through the dryer. For tubular configurations, this limitation can be avoided if L > or = Fc(10(3.8)/120 pi D), where L is the length of the tubular membrane, in centimeters, Fc is the gas flow rate, in mL/ min, and D is the diffusion coefficient for water in the carrier gas at the operating temperature of the dryer, in cm2/s. An efficient dryer that at room temperature dries gas to a dew point of -61 degrees C is described; the same dryer maintained at 0 degrees C yields a dew point of -80 degrees C and removes water as effectively as Mg(ClO4)2 or a dry ice/acetone slush. The use of Nafion membranes to construct devices capable of delivering gas streams with low but precisely controlled humidities is discussed.

Sensitivity of Runway Occupancy Time (ROT) to Various Rollout and Turnoff (ROTO) Factors. Volume 2; Complete Set of Plotted Data

NASA Technical Reports Server (NTRS)

Goldthorpe, S. H.

1997-01-01

The Terminal Area Productivity (TAP) research program was initiated by NASA to increase the airport capacity for transport aircraft operations. One element of the research program is called Low Visibility Landing and Surface Operations (LVLASO). A goal of the LVLASO research is to develop transport aircraft technologies which reduce Runway Occupancy Time (ROT) so that it does not become the limiting factor in the terminal area operations that determine the capacity of a runway. Under LVLASO, the objective of this study was to determine the sensitivity of ROT to various factors associated with the Rollout and Turnoff (ROTO) operation for transport aircraft. The following operational factors were studied and are listed in the order of decreasing ROT sensitivity: ice/flood runway surface condition, exit entrance ground speed, number of exits, high-speed exit locations and spacing, aircraft type, touchdown ground speed standard deviation, reverse thrust and braking method, accurate exit prediction capability, maximum reverse thrust availability, spiral-arc vs. circle-arc exit geometry, dry/slush/wet/snow runway surface condition, maximum allowed deceleration, auto asymmetric braking on exit, do not stow reverse thrust before the exit, touchdown longitudinal location standard deviation, flap setting, anti-skid efficiency, crosswind conditions, stopping on the exit and touchdown lateral offset.

Comparison of super-high-energy-propulsion-systems based on metallic hydrogen propellant for ES to LEO space transportation

NASA Technical Reports Server (NTRS)

Thierschmann, M.

1990-01-01

The application is studied of metallic H2 as a rocket propellant, which contains a specific energy of about 52 kcal/g in theory yielding a maximum specific impulse of 1700 s. With the convincing advantage of having a density 14 times that of conventional liquid H2/liquid O2 propellants, metallic H2 could satisfy the demands of advanced launch vehicle propulsion for the next millennium. Provided that there is an atomic metallic state of H2, and that this state is metastable at ambient pressure, which still is not proven, the results are given of the study of some important areas, which concern the production of metallic H2, the combustion, chamber cooling, and storage. The results show that the use of metallic H2 as rocket propellant could lead to revolutionary changes in space vehicle philosophy toward small size, small weight, and high performance single stage to orbit systems. The use of high metallic H2 mass fractions results in a dramatic reduction of required propellant volume, while gas temperatures in the combustion chamber exceed 5000 K. Furthermore, it follows, that H2 (liquid or slush) is the most favorable candidate as working fluid. Jet generated noise due to high exhaust velocities could be a problem.

The dynamic bacterial communities of a melting High Arctic glacier snowpack

PubMed Central

Hell, Katherina; Edwards, Arwyn; Zarsky, Jakub; Podmirseg, Sabine M; Girdwood, Susan; Pachebat, Justin A; Insam, Heribert; Sattler, Birgit

2013-01-01

Snow environments can occupy over a third of land surface area, but little is known about the dynamics of snowpack bacteria. The effect of snow melt on bacterial community structure and diversity of surface environments of a Svalbard glacier was examined using analyses of 16S rRNA genes via T-RFLP, qPCR and 454 pyrosequencing. Distinct community structures were found in different habitat types, with changes over 1 week apparent, in particular for the dominant bacterial class present, Betaproteobacteria. The differences observed were consistent with influences from depositional mode (snowfall vs aeolian dusts), contrasting snow with dust-rich snow layers and near-surface ice. Contrary to that, slush as the decompositional product of snow harboured distinct lineages of bacteria, further implying post-depositional changes in community structure. Taxa affiliated to the betaproteobacterial genus Polaromonas were particularly dynamic, and evidence for the presence of betaproteobacterial ammonia-oxidizing bacteria was uncovered, inviting the prospect that the dynamic bacterial communities associated with snowpacks may be active in supraglacial nitrogen cycling and capable of rapid responses to changes induced by snowmelt. Furthermore the potential of supraglacial snowpack ecosystems to respond to transient yet spatially extensive melting episodes such as that observed across most of Greenland's ice sheet in 2012 merits further investigation. PMID:23552623

The dynamic bacterial communities of a melting High Arctic glacier snowpack.

PubMed

Hell, Katherina; Edwards, Arwyn; Zarsky, Jakub; Podmirseg, Sabine M; Girdwood, Susan; Pachebat, Justin A; Insam, Heribert; Sattler, Birgit

2013-09-01

Snow environments can occupy over a third of land surface area, but little is known about the dynamics of snowpack bacteria. The effect of snow melt on bacterial community structure and diversity of surface environments of a Svalbard glacier was examined using analyses of 16S rRNA genes via T-RFLP, qPCR and 454 pyrosequencing. Distinct community structures were found in different habitat types, with changes over 1 week apparent, in particular for the dominant bacterial class present, Betaproteobacteria. The differences observed were consistent with influences from depositional mode (snowfall vs aeolian dusts), contrasting snow with dust-rich snow layers and near-surface ice. Contrary to that, slush as the decompositional product of snow harboured distinct lineages of bacteria, further implying post-depositional changes in community structure. Taxa affiliated to the betaproteobacterial genus Polaromonas were particularly dynamic, and evidence for the presence of betaproteobacterial ammonia-oxidizing bacteria was uncovered, inviting the prospect that the dynamic bacterial communities associated with snowpacks may be active in supraglacial nitrogen cycling and capable of rapid responses to changes induced by snowmelt. Furthermore the potential of supraglacial snowpack ecosystems to respond to transient yet spatially extensive melting episodes such as that observed across most of Greenland's ice sheet in 2012 merits further investigation.

Frostbite of the liver: an unrecognized cause of primary non-function?

PubMed

Potanos, Kristina; Kim, Heung Bae

2014-02-01

Appropriate hypothermic packaging techniques are an essential part of organ procurement. We present a case in which deviation from standard packaging practice may have caused sub-zero storage temperatures during transport, resulting in a clinical picture resembling PNF. An 18-month-old male with alpha-1-antitrypsin deficiency underwent liver transplant from a size-matched pediatric donor. Upon arrival at the recipient hospital, ice crystals were noted in the UW solution. The transplant proceeded uneventfully with short ischemia times. Surprisingly, transaminases, INR, and total bilirubin were markedly elevated in the postoperative period but returned to near normal by discharge. Follow-up of over five yr has demonstrated normal liver function. Upon review, it was discovered that organ packaging during recovery included storage in the first bag with only 400 mL of UW solution, and pure ice in the second bag instead of slush. This suggests that the postoperative delayed graft function was related to sub-zero storage of the graft during transport. This is the first report of sub-zero cold injury, or frostbite, following inappropriate packaging of an otherwise healthy donor liver. The clinical picture closely resembled PNF, perhaps implicating this mechanism in other unexpected cases of graft non-function. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Landslide response signatures from storm Desmond (UK)/Synne (Norway), December 2015.

NASA Astrophysics Data System (ADS)

Dijkstra, Tom; Freeborough, Katy; Reeves, Helen; Nykjaer, Boje Soren; Sund, Monica; Devoli, Graziella; Banks, Vanessa

2016-04-01

Great Britain (GB) and coastal Norway share a common humid maritime climate and annually receive precipitation in the form of cyclonic low-pressure systems or as extra-tropical storms that travel across the Atlantic. Extreme meteorological events capable of triggering floods and landslides are becoming more frequent, with both GB and Norway being affected by a sequence of record-breaking precipitation events in the past decade. On the 5th and 6th of December 2015, storms Desmond/Synne struck northern GB and southwestern Norway with record-breaking rainfall; >340 mm in 24-hour in Cumbria (or 200% of long term average) and daily accumulations in Norway in excess of 140 mm and 236 mm/48hr. Landscape responses to hydro-meteorological stress are non-uniform and the result of a complex interaction of processes. Therefore, event-specific analysis provides an important tool to further our understanding, particularly to enhance the quality of daily landslide hazard assessments (DLHA) issued by the Norwegian Water Resources and Energy Directorate (NVE) and the British Geological Survey (BGS). The application of precipitation thresholds provides a useful first approximation for landslide triggering. However, antecedent conditioning of slopes and the spatial variability of precipitation signatures are important factors in determining the location of landslides. Given the magnitude of storms Desmond/Synne a much larger population of landslides was expected to occur. Within one month of the events occurring some 25 events are recorded in GB and circa 30 events in Norway. In GB most of these events are relatively small scale, dominated by translational slides and flows and about 80% of cases reported to occur along transport infrastructure. In Norway, roughly equal numbers of debris flows, shallow slides, rock falls, slush flows and snow avalanches are recorded in close proximity to infrastructure. As the media largely focused on simultaneous severe consequences of extensive flooding, landslide events appeared to be relatively under-reported. In the following days, information gradually emerged through anecdotal photographic evidence and social media of how landslide impacts. By their nature, rural areas with limited transport links will remain under-reported. Forensic analysis of landslide events highlights the importance of other contributing factors responsible for event localisation, particularly where larger events are concerned. There are many physiographic similarities of the landscapes of western Norway and those of Cumbria and Scotland. Many places can be characterised by relatively thin superficial deposits covering bedrock resulting in similar hydro-geological response mechanisms, e.g. the formation of debris flows at Rest and be Thankful (A83, Scotland) and at Sørfjorden (Hordaland, Norway). In Norway an impact transition was observed as the weather system moved further northeast first affecting areas with rain on soil causing landslides, then rain on snow causing slush flows. Impacts clearly are a function of 1) the characteristics of the medium covering the bedrock (soil type, snow cover), 2) the antecedent soil moisture condition, and 3) precipitation signature. Comparative analyses lead to improved understanding of triggering thresholds and synergies delivered by transfer of skill sets on landslide data management, analysis and communication for DLHA.

Influence of Sea Ice Crack Formation on the Spatial Distribution of Nutrients and Microalgae in Flooded Antarctic Multiyear Ice

NASA Astrophysics Data System (ADS)

Nomura, Daiki; Aoki, Shigeru; Simizu, Daisuke; Iida, Takahiro

2018-02-01

Cracks are common and natural features of sea ice formed in the polar oceans. In this study, a sea ice crack in flooded, multiyear, land-fast Antarctic sea ice was examined to assess its influence on biological productivity and the transport of nutrients and microalgae into the upper layers of neighboring sea ice. The water inside the crack and the surrounding host ice were characterized by a strong discoloration (brown color), an indicator of a massive algal bloom. Salinity and oxygen isotopic ratio measurements indicated that 64-84% of the crack water consisted of snow meltwater supplied during the melt season. Measurements of nutrient and chlorophyll a concentrations within the slush layer pool (the flooded layer at the snow-ice interface) revealed the intrusion of water from the crack, likely forced by mixing with underlying seawater during the tidal cycle. Our results suggest that sea ice crack formation provides conditions favorable for algal blooms by directly exposing the crack water to sunlight and supplying nutrients from the under-ice water. Subsequently, constituents of the crack water modified by biological activity were transported into the upper layer of the flooded sea ice. They were then preserved in the multiyear ice column formed by upward growth of sea ice caused by snow ice formation in areas of significant snow accumulation.

Recent Advances and Applications in Cryogenic Propellant Densification Technology

NASA Technical Reports Server (NTRS)

Tomsik, Thomas M.

2000-01-01

This purpose of this paper is to review several historical cryogenic test programs that were conducted at the NASA Glenn Research Center (GRC), Cleveland, Ohio over the past fifty years. More recently these technology programs were intended to study new and improved denser forms of liquid hydrogen (LH2) and liquid oxygen (LO2) cryogenic rocket fuels. Of particular interest are subcooled cryogenic propellants. This is due to the fact that they have a significantly higher density (eg. triple-point hydrogen, slush etc.), a lower vapor pressure and improved cooling capacity over the normal boiling point cryogen. This paper, which is intended to be a historical technology overview, will trace the past and recent development and testing of small and large-scale propellant densification production systems. Densifier units in the current GRC fuels program, were designed and are capable of processing subcooled LH2 and L02 propellant at the X33 Reusable Launch Vehicle (RLV) scale. One final objective of this technical briefing is to discuss some of the potential benefits and application which propellant densification technology may offer the industrial cryogenics production and end-user community. Density enhancements to cryogenic propellants (LH2, LO2, CH4) in rocket propulsion and aerospace application have provided the opportunity to either increase performance of existing launch vehicles or to reduce the overall size, mass and cost of a new vehicle system.

Holocene hillslope processes and deposits in two U-shaped mountain valleys in western Norway

NASA Astrophysics Data System (ADS)

Laute, K.; Beylich, A. A.

2012-04-01

This doctoral research project is integrated in the Norwegian Research Council (NFR) funded SedyMONT-Norway Project within the ESF EUROCORES TOPO-EUROPE SedyMONT (Timescales of sediment dynamics, climate and topographic change in mountain landscapes) Programme. Research is carried out within two steep, U-shaped and glacier-connected tributary valleys (Erdalen and Bødalen) on the western side of the Jostedalsbreen ice cap in western Norway. Contemporary denudative processes in both valley systems include rock and boulder falls, avalanches, slush flows, debris flows, creep processes, wash- and chemical denudation and fluvial transport of solutes, suspended sediments and bedload. The main aims of this research project which are approached within a Holocene to contemporary timescale are: (i) to investigate the spatio-temporal variability of Holocene hillslope development, (ii) to analyse more specificly the morphometric influences and geomorphic consequences of the Little Ice Age (LIA) glacier advance on selected hillslope systems within defined headwater areas in both valleys, (iii) to study morphometric and meteorological controls of contemporary denudative slope processes as well as (iv) to quantify the rates of sediment delivery from headwater areas and its changes over time. A process-based approach is applied using a variety of different methods and techniques. Focus is on different temporal (Holocene to contemporary) and spatial (selected hillslope systems, headwater areas and entire valley system) scales. The applied methods include orthophoto- and topographical map interpretation, GIS and DEM computing, geomorphological fieldmapping and hillslope profile surveying complemented by relative dating techniques (lichenometry and dendrochronology), geophysical investigations and terrestrial laser scanning (LIDAR). For monitoring contemporary rates of slope processes a designed monitoring programme (running since 2009) with a wide spectrum of instrumentation; e.g. installed nets for collecting freshly accumulated rockfall debris, continuous photo-monitoring of rapid mass movement events (avalanches, slush- and debris flows) as well as installed temperature loggers both in rock walls and talus slopes for analysing rock temperatures and mechanical weathering is applied at selected hillslope test sites within the two valley systems. The overall tendency of landscape development is a Postglacial modification of the defined U-shaped valley morphometry (valley widening) throughout rockwall retreat and connected accumulation of debris material beneath these rockwalls. Active fluvial material removal at the base of slopes is almost negligible due to a very limited hillslope-channel coupling in both valleys. Results regarding the spatio-temporal variability of Holocene hillslope development show Holocene rockwall retreat rates for the two valleys which are in a comparable range with other estimates of rockwall retreat rates in other cold mountain environments worldwide. Further on the findings indicate probably higher accumulation rates of slope deposits mainly throughout an enhanced rockfall activity shortly after the glacier retreat as compared to subrecent and contemporary rates. Within the LIA period a recognizable modification of hillslopes in proximity to the outlet glaciers of the Jostedalsbreen is noticeable. A more complex hillslope morphometry (steepening of lower hillslope segments) as well as a more complex composition (inherited by a combination of debris from gravitational processes and lateral moraine ridges) of loose material generating a higher intensity of currently acting slope processes within the hillslope systems located inside of the LIA glacial advance limit as compared to hillslopes situated outside of this limit is found.

Erosion and entrainment of snow and ice by pyroclastic density currents: some outstanding questions (Invited)

NASA Astrophysics Data System (ADS)

Walder, J. S.

2010-12-01

A pyroclastic density current moving over snow is likely to transform to a lahar if the pyroclasts incorporate enough (melting) snow and meltwater to bring the bulk water content of the mixture to about 35% by volume. However, the processes by which such a mixture forms are still not well understood. Walder (Bull. Volcanol., v. 62, 2000) showed experimentally the existence of an erosion mechanism that functions even in the absence of relative shear motion between pyroclasts and snow substrate: a portion of the snow melted by a blanket of pyroclasts is vaporized; the flux of water vapor upward through the pyroclasts may be enough to fluidize the pyroclasts, which then convect, rapidly scour the snow substrate and transform into a slurry. But these experiments do not tell us how moving pyroclasts would erode snow, and simply releasing a hot grain flow over a snow surface in the lab gives misleading results owing to improper scaling of τ/σ , the ratio of the shear stress τ exerted by the pyroclastic flow to the shear strength σ of snow. There seems to be no way around this problem for experiments with actual snow. However, it may be possible to circumvent the scaling problem by replacing the snow substrate by a gas-fluidized particle bed: by varying the gas flux, the apparent shear strength of the particle bed can be varied. Such an investigation of erosional processes could be done at room temperature. Snow-avalanche studies (for example, Gauer and Issler, Ann. Glaciol. v. 38, 2003) may provide some insight into snow erosion by a pyroclastic density current. Snow is eroded at the base of a dense snow avalanche by abrasion, particle impacts, and—at the avalanche head—by plowing and a “blasting” mechanism associated with compression of the snowpack and expulsion of pore fluid (air). Erosion at the avalanche head seems to be particularly important. Similar processes are likely to occur when the over-riding flow comprises hot grains. The laboratory release of a hot grain flow over snow, although improperly scaled for investigating erosive processes, does demonstrate that snow hydrology and snowpack stability may be critical in the transformation of pyroclastic density currents to lahars. When such an experiment is run in a sloping flume, with meltwater able to drain freely at the base of the snow layer, the hot grain flow spreads over the snow surface and then comes to rest--no slurry is produced. In contrast, if meltwater drainage is blocked, the wet snow layer fails at its bed, mobilizes as a slush flow, and mixes with the hot grains to form a slurry. Ice layers within a natural snowpack would likewise block meltwater drainage and be conducive to the formation of slush flows. Abrasion and particle impacts—processes that have been studied intensively by engineers concerned with the wear of surfaces in machinery—probably play an important role in the erosion of glacier ice by pyroclastic density currents. A prime example may be the summit ice cap of Nevado del Ruiz, Colombia, which was left grooved by the eruption of 1985 (Thouret, J. Volcanol. Geotherm. Res., v. 41, 1990). Erosion of glacier ice is also strongly controlled by the orientation of crevasses, which can “capture” pyroclastic currents. This phenomenon was well displayed at Mount Redoubt, Alaska during the eruptions of 1989-90 and 2009.

An examination of the roles played by early adolescent children in interactions with their local food environment.

PubMed

Engler-Stringer, Rachel; Schaefer, Joelle; Ridalls, Tracy

2016-06-09

The purpose of this study was to examine how pre- and early adolescent (10-14 years old) children from a wide range of neighbourhoods interact with their local food environment (FE), with a focus on the foods and food sources they access and their locations. Children in this age group are developing independence and mobility within (and beyond) their home neighbourhoods but are somewhat geographically bound as they cannot yet drive. This research consists of qualitative interviews with 31 children (15 males, 16 females) aged 10-14 years living in socio-economically diverse neighbourhoods across Saskatoon, SK. A thematic analysis was conducted. Children's descriptions of what constitutes their neighbourhood FE were varied, ranging from a couple of city blocks to several kilometres from home. Children were familiar with the types of establishment that sell food within their perceived neighbourhood. When children purchased their own food they most frequently cited buying snacks such as ice cream, candy and slushes, and the majority of these purchases were made in convenience stores, gas stations and grocery stores. Few children reported frequenting fast-food or other restaurants without adults, and when they did it was usually to buy snacks such as French fries and ice cream rather than meals. Our results highlight the importance of interventions targeted to this age group, in which personal food choices were reported almost exclusively as being energy- but not nutrient-dense snack foods.

Atmospheric H2O2 measurement: comparison of cold trap method with impinger bubbling method

NASA Technical Reports Server (NTRS)

Sakugawa, H.; Kaplan, I. R.

1987-01-01

Collection of atmospheric H2O2 was performed by a cold trap method using dry ice-acetone as the refrigerant. The air was drawn by a pump into a glass gas trap immersed in the dry ice-acetone slush in a dewar flask at a flow rate of 2.5 l min-1 for approximately 2 h. Collection efficiency was > 99% and negligible interferences by O3, SO2 or organic matter with the collected H2O2 in the trap were observed. This method was compared with the air impinger bubbling method which has been previously described (Kok et al., 1978a, b, Envir. Sci. Technol. 12, 1072-1080). The measured total peroxide (H2O2 + organic peroxide) values in a series of aim samples collected by the impinger bubbling method (0.06-3.7 ppb) were always higher than those obtained by the cold trap method (0.02-1.2 ppb). Laboratory experiments suggest that the difference in values between the two methods probably results from the aqueous phase generation of H2O2 and organic peroxide in the impinger solution by a reaction of atmospheric O3 with olefinic and aromatic compounds. If these O3-organic compound reactions which occur in the impinger also occur in aqueous droplets in the atmosphere, the process could be very important for aqueous phase generation of H2O2 in clouds and rainwater.

Dynamic Defrosting on Scalable Superhydrophobic Surfaces

DOE PAGES

Murphy, Kevin R.; McClintic, William T.; Lester, Kevin C.; ...

2017-06-27

Recent studies have shown that frost can grow in a suspended Cassie state on nanostructured superhydrophobic surfaces. During defrosting, the melting sheet of Cassie frost spontaneously dewets into quasi-spherical slush droplets that are highly mobile. Promoting Cassie frost would therefore seem advantageous from a defrosting standpoint; however, nobody has systematically compared the efficiency of defrosting Cassie ice versus defrosting conventional surfaces. Here, we characterize the defrosting of an aluminum plate, one-half of which exhibits a superhydrophobic nanostructure while the other half is smooth and hydrophobic. For thick frost sheets (>1 mm), the superhydrophobic surface was able to dynamically shed themore » meltwater, even at very low tilt angles. In contrast, the hydrophobic surface was unable to shed any appreciable meltwater even at a 90° tilt angle. For thin frost layers (≲1 mm), not even the superhydrophobic surface could mobilize the meltwater. We attribute this to the large apparent contact angle of the meltwater, which for small amounts of frost serves to minimize coalescence events and prevent droplets from approaching the capillary length. Finally, we demonstrate a new mode of dynamic defrosting using an upside-down surface orientation, where the melting frost was able to uniformly detach from the superhydrophobic side and subsequently pull the frost from the hydrophobic side in a chain reaction. Treating surfaces to enable Cassie frost is therefore very desirable for enabling rapid and low-energy thermal defrosting, but only for frost sheets that are sufficiently thick.« less

Operational early warning of shallow landslides in Norway: Evaluation of landslide forecasts and associated challenges

NASA Astrophysics Data System (ADS)

Dahl, Mads-Peter; Colleuille, Hervé; Boje, Søren; Sund, Monica; Krøgli, Ingeborg; Devoli, Graziella

2015-04-01

The Norwegian Water Resources and Energy Directorate (NVE) runs a national early warning system (EWS) for shallow landslides in Norway. Slope failures included in the EWS are debris slides, debris flows, debris avalanches and slush flows. The EWS has been operational on national scale since 2013 and consists of (a) quantitative landslide thresholds and daily hydro-meteorological prognosis; (b) daily qualitative expert evaluation of prognosis / additional data in decision to determine warning levels; (c) publication of warning levels through various custom build internet platforms. The effectiveness of an EWS depends on both the quality of forecasts being issued, and the communication of forecasts to the public. In this analysis a preliminary evaluation of landslide forecasts from the Norwegian EWS within the period 2012-2014 is presented. Criteria for categorizing forecasts as correct, missed events or false alarms are discussed and concrete examples of forecasts falling into the latter two categories are presented. The evaluation show a rate of correct forecasts exceeding 90%. However correct forecast categorization is sometimes difficult, particularly due to poorly documented landslide events. Several challenges has to be met in the process of further lowering rates of missed events of false alarms in the EWS. Among others these include better implementation of susceptibility maps in landslide forecasting, more detailed regionalization of hydro-meteorological landslide thresholds, improved prognosis on precipitation, snowmelt and soil water content as well as the build-up of more experience among the people performing landslide forecasting.

Dynamic Defrosting on Scalable Superhydrophobic Surfaces.

PubMed

Murphy, Kevin R; McClintic, William T; Lester, Kevin C; Collier, C Patrick; Boreyko, Jonathan B

2017-07-19

Recent studies have shown that frost can grow in a suspended Cassie state on nanostructured superhydrophobic surfaces. During defrosting, the melting sheet of Cassie frost spontaneously dewets into quasi-spherical slush droplets that are highly mobile. Promoting Cassie frost would therefore seem advantageous from a defrosting standpoint; however, nobody has systematically compared the efficiency of defrosting Cassie ice versus defrosting conventional surfaces. Here, we characterize the defrosting of an aluminum plate, one-half of which exhibits a superhydrophobic nanostructure while the other half is smooth and hydrophobic. For thick frost sheets (>1 mm), the superhydrophobic surface was able to dynamically shed the meltwater, even at very low tilt angles. In contrast, the hydrophobic surface was unable to shed any appreciable meltwater even at a 90° tilt angle. For thin frost layers (≲1 mm), not even the superhydrophobic surface could mobilize the meltwater. We attribute this to the large apparent contact angle of the meltwater, which for small amounts of frost serves to minimize coalescence events and prevent droplets from approaching the capillary length. Finally, we demonstrate a new mode of dynamic defrosting using an upside-down surface orientation, where the melting frost was able to uniformly detach from the superhydrophobic side and subsequently pull the frost from the hydrophobic side in a chain reaction. Treating surfaces to enable Cassie frost is therefore very desirable for enabling rapid and low-energy thermal defrosting, but only for frost sheets that are sufficiently thick.

Guide for Hydrogen Hazards Analysis on Components and Systems

NASA Technical Reports Server (NTRS)

Beeson, Harold; Woods, Stephen

2003-01-01

The physical and combustion properties of hydrogen give rise to hazards that must be considered when designing and operating a hydrogen system. One of the major concerns in the use of hydrogen is that of fire or detonation because of hydrogen's wide flammability range, low ignition energy, and flame speed. Other concerns include the contact and interaction of hydrogen with materials, such as the hydrogen embrittlement of materials and the formation of hydrogen hydrides. The low temperature of liquid and slush hydrogen bring other concerns related to material compatibility and pressure control; this is especially important when dissimilar, adjoining materials are involved. The potential hazards arising from these properties and design features necessitate a proper hydrogen hazards analysis before introducing a material, component, or system into hydrogen service. The objective of this guide is to describe the NASA Johnson Space Center White Sands Test Facility hydrogen hazards analysis method that should be performed before hydrogen is used in components and/or systems. The method is consistent with standard practices for analyzing hazards. It is recommended that this analysis be made before implementing a hydrogen component qualification procedure. A hydrogen hazards analysis is a useful tool for hydrogen-system designers, system and safety engineers, and facility managers. A hydrogen hazards analysis can identify problem areas before hydrogen is introduced into a system-preventing damage to hardware, delay or loss of mission or objective, and possible injury or loss of life.

Dynamic Defrosting on Scalable Superhydrophobic Surfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Murphy, Kevin R.; McClintic, William T.; Lester, Kevin C.

Recent studies have shown that frost can grow in a suspended Cassie state on nanostructured superhydrophobic surfaces. During defrosting, the melting sheet of Cassie frost spontaneously dewets into quasi-spherical slush droplets that are highly mobile. Promoting Cassie frost would therefore seem advantageous from a defrosting standpoint; however, nobody has systematically compared the efficiency of defrosting Cassie ice versus defrosting conventional surfaces. Here, we characterize the defrosting of an aluminum plate, one-half of which exhibits a superhydrophobic nanostructure while the other half is smooth and hydrophobic. For thick frost sheets (>1 mm), the superhydrophobic surface was able to dynamically shed themore » meltwater, even at very low tilt angles. In contrast, the hydrophobic surface was unable to shed any appreciable meltwater even at a 90° tilt angle. For thin frost layers (≲1 mm), not even the superhydrophobic surface could mobilize the meltwater. We attribute this to the large apparent contact angle of the meltwater, which for small amounts of frost serves to minimize coalescence events and prevent droplets from approaching the capillary length. Finally, we demonstrate a new mode of dynamic defrosting using an upside-down surface orientation, where the melting frost was able to uniformly detach from the superhydrophobic side and subsequently pull the frost from the hydrophobic side in a chain reaction. Treating surfaces to enable Cassie frost is therefore very desirable for enabling rapid and low-energy thermal defrosting, but only for frost sheets that are sufficiently thick.« less

Vapor pressures of acetylene at low temperatures

NASA Technical Reports Server (NTRS)

Masterson, C. M.; Allen, John E., Jr.; Kraus, G. F.; Khanna, R. K.

1990-01-01

The atmospheres of many of the outer planets and their satellites contain a large number of hydrocarbon species. In particular, acetylene (C2H2) has been identified at Jupiter, Saturn and its satellite Titan, Uranus and Neptune. In the lower atmospheres of these planets, where colder temperatures prevail, the condensation and/or freezing of acetylene is probable. In order to obtain accurate models of the acetylene in these atmospheres, it is necessary to have a complete understanding of its vapor pressures at low temperatures. Vapor pressures at low temperatures for acetylene are being determined. The vapor pressures are measured with two different techniques in order to cover a wide range of temperatures and pressures. In the first, the acetylene is placed in a sample tube which is immersed in a low temperature solvent/liquid nitrogen slush bath whose temperature is measured with a thermocouple. The vapor pressure is then measured directly with a capacitance manometer. For lower pressures, a second technique which was called the thin-film infrared method (TFIR) was developed. It involves measuring the disappearance rate of a thin film of acetylene at a particular temperature. The spectra are then analyzed using previously determined extinction coefficient values, to determine the disappearance rate R (where R = delta n/delta t, the number of molecules that disappear per unit time). This can be related to the vapor pressure directly. This technique facilitates measurement of the lower temperatures and pressures. Both techniques have been calibrated using CO2, and have shown good agreement with the existing literature data.

Europa's Broken Ice

NASA Technical Reports Server (NTRS)

1996-01-01

Jupiter's moon Europa, as seen in this image taken June 27, 1996 by NASA's Galileo spacecraft, displays features in some areas resembling ice floes seen in Earth's polar seas. Europa, about the size of Earth's moon, has an icy crust that has been severely fractured, as indicated by the dark linear, curved, and wedged-shaped bands seen here. These fractures have broken the crust into plates as large as 30 kilometers (18.5 miles) across. Areas between the plates are filled with material that was probably icy slush contaminated with rocky debris. Some individual plates were separated and rotated into new positions. Europa's density indicates that it has a shell of water ice as thick as 100 kilometers (about 60 miles), parts of which could be liquid. Currently, water ice could extend from the surface down to the rocky interior, but the features seen in this image suggest that motion of the disrupted icy plates was lubricated by soft ice or liquid water below the surface at the time of disruption. This image covers part of the equatorial zone of Europa and was taken from a distance of 156,000 kilometers (about 96,300 miles) by the solid-state imager camera on the Galileo spacecraft. North is to the right and the sun is nearly directly overhead. The area shown is about 360 by 770 kilometers (220-by-475 miles or about the size of Nebraska), and the smallest visible feature is about 1.6 kilometers (1 mile) across. The Jet Propulsion Laboratory manages the Galileo mission for NASA's Office of Space Science.

Hydrologic conditions and hazards in the Kennicott River basin, Wrangell-St. Elias National Park Preserve, Alaska

USGS Publications Warehouse

Rickman, R.L.; Rosenkrans, D.S.

1997-01-01

McCarthy, Alaska, is on the Kennicott River, about 1 mile from the terminus of Kennicott Glacier in the Wrangell-St. Elias National Park and Preserve. Most visitors to McCarthy and the park cross the West Fork Kennicott River using a hand-pulled tram and cross the East Fork Kennicott River on a temporary footbridge. Outburst floods from glacier-dammed lakes result in channel erosion, aggradation, and migration of the Kennicott River, which disrupt transportation links, destroy property, and threaten life. Hidden Creek Lake, the largest of six glacier-dammed lakes in the Kennicott River Basin, has annual outbursts that cause the largest floods on the Kennicott River. Outbursts from Hidden Creek Lake occur from early fall to mid-summer, and lake levels at the onset of the outbursts have declined between 1909 and 1995. Criteria for impending outbursts for Hidden Creek Lake include lake stage near or above 3,000 to 3,020 feet, stationary or declining lake stage, evidence of recent calving of large ice blocks from the ice margin, slush ice and small icebergs stranded on the lakeshore, and fresh fractures in the ice-margin region. The lower Kennicott Glacier has thinned and retreated since about 1860. The East and West Fork Kennicott River channels migrated in response to changes in the lower Kennicott Glacier. The largest channel changes occur during outburst floods from Hidden Creek Lake, whereas channel changes from the other glacier-dammed lake outbursts are small. Each year, the West Fork Kennicott River conveys a larger percentage of the Kennicott Glacier drainage than it did the previous year. Outburst floods on the Kennicott River cause the river stage to rise over a period of several hours. Smaller spike peaks have a very rapid stage rise. Potential flood magnitude was estimated by combining known maximum discharges from Hidden Creek Lake and Lake Erie outburst floods with a theoretical large regional flood. Flood hazard areas at the transportation corridor were delineated, and possible future geomorphological changes were hypothesized. McCarthy, Alaska, is on the Kennicott River, about 1 mile from the terminus of Kennicott Glacier in the Wrangell-St. Elias National Park and Preserve. Most visitors to McCarthy and the park cross the West Fork Kennicott River using a hand-pulled tram and cross the East Fork Kennicott River on a temporary footbridge. Outburst floods from glacier-dammed lakes result in channel erosion, aggradation, and migration of the Kennicott River, which disrupt transportation links, destroy property, and threaten life. Hidden Creek Lake, the largest of six glacier-dammed lakes in the Kennicott River Basin, has annual outbursts that cause the largest floods on the Kennicott River. Outbursts from Hidden Creek Lake occur from early fall to mid-summer, and lake levels at the onset of the outbursts have declined between 1909 and 1995. Criteria for impending outbursts for Hidden Creek Lake include lake stage near or above 3,000 to 3,020 feet, stationary or declining lake stage, evidence of recent calving of large ice blocks from the ice margin, slush ice and small icebergs stranded on the lakeshore, and fresh fractures in the ice-margin region. The lower Kennicott Glacier has thinned and retreated since about 1860. The East and West Fork Kennicott River channels migrated in response to changes in the lower Kennicott Glacier. The largest channel changes occur during outburst floods from Hidden Creek Lake, whereas channel changes from the other glacier-dammed lake outbursts are small. Each year, the West Fork Kennicott River conveys a larger percentage of the Kennicott Glacier drainage than it did the previous year. Outburst floods on the Kennicott River cause the river stage to rise over a period of several hours. Smaller spike peaks have a very rapid stage rise. Potential flood magnitude was estimated by combining known maximum discharges from Hidden Creek Lake and Lake Erie outburst floods with

Europa's Habitability follows from Classical Dynamical Astronomy

NASA Astrophysics Data System (ADS)

Greenberg, R.

2001-11-01

Celestial mechanics is responsible for Jupiter's satellite Europa being a possible site for life in the solar system. The Laplace orbital resonance drives a substantial eccentricity. The mutually dependent relationship between orbital and rotational evolution and tidal processes in turn controls Europa's heating and stress. Heat is likely adequate to maintain a liquid water ocean, and to keep the surface ice thin. Tidal stress can explain characteristic and ubiquitous crack patterns (global and cycloidal), as well as drive observed shear displacement features. The characteristic ridge sets that cover tectonic terrain are likely built by tidal pumping of oceanic fluid and slush through cracks to the surface on a daily basis. Nearly half the surface is chaotic terrain, with morphology and other characteristics indicative of melt-through from below. Formation of both chaotic and tectonic terrains has continually resurfaced the satellite, while connecting the ocean to the surface and providing a variety of evolving environmental niches. As a result of tides, liquid water would daily bathe crustal cracks and surfaces with heat, transporting and mixing substances vertically. Thus a variety of habitable environments likely exist in the crust. Moreover, exposure of the ocean to the surface in the ways described here satisfies a necessary condition for life in the ocean as well, by providing access to oxidants which are available near the surface. These processes were recent, and thus most likely continue today. Longer term changes in environmental conditions in the crust, such as deactivation of individual cracks after thousands of years (due to non-synchronous rotation) and later crustal thawing (releasing any trapped organisms), provided drivers for adaptation, as well as opportunity for evolution. This work is supported by the NASA Planetary Geology and Geophysics Program and the NSF Life in Extreme Environments Program.

Dark Bands on Europa

NASA Technical Reports Server (NTRS)

1996-01-01

Dark crisscrossing bands on Jupiter's moon Europa represent widespread disruption from fracturing and the possible eruption of gases and rocky material from the moon's interior in this four-frame mosaic of images from NASA's Galileo spacecraft. These and other features suggest that soft ice or liquid water was present below the ice crust at the time of disruption. The data do not rule out the possibility that such conditions exist on Europa today. The pictures were taken from a distance of 156,000 kilometers (about 96,300 miles) on June 27, 1996. Many of the dark bands are more than 1,600 kilometers (1,000 miles) long, exceeding the length of the San Andreas fault of California. Some of the features seen on the mosaic resulted from meteoritic impact, including a 30- kilometer (18.5 mile) diameter crater visible as a bright scar in the lower third of the picture. In addition, dozens of shallow craters seen in some terrains along the sunset terminator zone (upper right shadowed area of the image) are probably impact craters. Other areas along the terminator lack craters, indicating relatively youthful surfaces, suggestive of recent eruptions of icy slush from the interior. The lower quarter of the mosaic includes highly fractured terrain where the icy crust has been broken into slabs as large as 30 kilometers (18.5 miles) across. The mosaic covers a large part of the northern hemisphere and includes the north pole at the top of the image. The sun illuminates the surface from the left. The area shown is centered on 20 degrees north latitude and 220 degrees west longitude and is about as wide as the United States west of the Mississippi River. The Galileo mission is managed by NASA's Jet Propulsion Laboratory.

Frost flowers and sea-salt aerosols over seasonal sea-ice areas in northwestern Greenland during winter-spring

NASA Astrophysics Data System (ADS)

Hara, Keiichiro; Matoba, Sumito; Hirabayashi, Motohiro; Yamasaki, Tetsuhide

2017-07-01

Sea salts and halogens in aerosols, frost flowers, and brine play an important role in atmospheric chemistry in polar regions. Simultaneous sampling and observations of frost flowers, brine, and aerosol particles were conducted around Siorapaluk in northwestern Greenland during December 2013 to March 2014. Results show that water-soluble frost flower and brine components are sea-salt components (e.g., Na+, Cl-, Mg2+, K+, Ca2+, Br-, and iodine). Concentration factors of sea-salt components of frost flowers and brine relative to seawater were 1.14-3.67. Sea-salt enrichment of Mg2+, K+, Ca2+, and halogens (Cl-, Br-, and iodine) in frost flowers is associated with sea-salt fractionation by precipitation of mirabilite and hydrohalite. High aerosol number concentrations correspond to the occurrence of higher abundance of sea-salt particles in both coarse and fine modes, and blowing snow and strong winds. Aerosol number concentrations, particularly in coarse mode, are increased considerably by release from the sea-ice surface under strong wind conditions. Sulfate depletion by sea-salt fractionation was found to be limited in sea-salt aerosols because of the presence of non-sea-salt (NSS) SO42-. However, coarse and fine sea-salt particles were found to be rich in Mg. Strong Mg enrichment might be more likely to proceed in fine sea-salt particles. Magnesium-rich sea-salt particles might be released from the surface of snow and slush layer (brine) on sea ice and frost flowers. Mirabilite-like and ikaite-like particles were identified only in aerosol samples collected near new sea-ice areas. From the field evidence and results from earlier studies, we propose and describe sea-salt cycles in seasonal sea-ice areas.

Galapagos hotspot-spreading center system: 1. Spatial petrological and geochemical variations (83/sup 0/W-101/sup 0/W)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schilling, J.; Kingsley, R.H.; Devine, J.D.

We report on the petrology and geochemistry of basalts dredged at 40--50 km intervals along the Galapagos Spreading Center, between 83/sup 0/W and 101/sup 0/W (40 stations). Emphasis is on spatial variations of 'whole rock' major elements, rare earths, trace metals of the first transition series, and the nature of phenocryst assemblages and their abundances. These results provide new constraints on the nature and scale of mantle source heterogeneities, melting conditions, thermal field, and dynamics of crustal formation of the region. We suggest that ridge segments outside the high magnetic amplitude zone are at a steady state as a resultmore » of passive seafloor spreading. Basalts from these segments are apparently derived from an asthenosphere relatively uniformally depleted in incompatible elements, which appears of worldwide extent. We reject Vogt and DeBoer's (1976) model invoking damming at fracture zones of subaxial asthenosphere flow of crystal slushes and increasing fractional crystallization down the flow line, because this model would not explain the gradients in REE observed about the Galapagos Platform. Our preferred model combines the mantle-plume binary mixing model of Schilling (1973) with the concept of recurring rift propagation proposed by Hey (1977a). We further propose that pulsating mantle plume flux, perhaps in the form of a chain of blobs, may initiate the development of new rifts and their propagation. The present position of the tips of such new propagating rifts locate the wave fronts of such pulsating mantle plume flow. A two million year period is suggested for the last 4 m.y. from Wilson and Hey's (1979) information Rigorous testing of our preferred model is possible.« less

A Dark Spot on Europa

NASA Technical Reports Server (NTRS)

1998-01-01

This view taken by NASA's Galileo spacecraft of Jupiter's icy moon Europa focuses on a dark, smooth region whose center is the lowest area in this image. To the west (left), it is bounded by a cliff and terraces, which might have been formed by normal faulting. The slopes toward the east (right) leading into the dark spot are gentle.

Near the center of the dark area, it appears the dark materials have covered some of the bright terrain and ridges. This suggests that when the dark material was deposited, it may have been a fluid or an icy slush.

Only a few impact craters are visible, with some of them covered or flooded by dark material. Some appear in groups, which may indicate that they are secondary craters formed by debris excavated during a larger impact event. A potential source for these is the nearby crater Mannann`an.

North is to the top of the picture which is centered at 1 degree south latitude and 225 degrees west longitude. The images in this mosaic have been re-projected to 50 meters (55 yards) per picture element. They were obtained by the Solid State Imaging (SSI) system on March 29, 1998, during Galileo's fourteenth orbit of Jupiter, at ranges as close as 1940 kilometers (1,200 miles) from Europa.

The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at URL http://www.jpl.nasa.gov/galileo/sepo

Effects of various combinations of cryoprotectants and cooling speed on the survival and further development of mouse oocytes after vitrification

PubMed Central

Cha, Soo Kyung; Kim, Bo Yeun; Kim, Mi Kyung; Kim, You Shin; Lee, Woo Sik

2011-01-01

Objective The objectives of this study were to analyze efficacy of immature and mature mouse oocytes after vitrification and warming by applying various combinations of cryoprotectants (CPAs) and/or super-rapid cooling using slush nitrogen (SN2). Methods Four-week old ICR female mice were superovulated for GV- and MII-stage oocytes. Experimental groups were divided into two groups. Ethylene glycol (EG) only group: pre-equilibrated with 1.5 M EG for 2.5 minutes and then equilibrated with 5.5 M EG and 1.0 M sucrose for 20 seconds. EG+dimethylsulfoxide (DMSO) group: pre-equilibrated with 1.3 M EG+1.1 M DMSO for 2.5 minutes and equilibrated with 2.7 M EG+2.1 M DMSO+0.5 M sucrose for 20 seconds. The oocytes were loaded onto grids and plunged into SN2 or liquid nitrogen (LN2). Stored oocytes were warmed by a five-step method, and then their survival, maturation, cleavage, and developmental rates were observed. Results The EG only and EG+DMSO groups showed no significant difference in survival of immature oocytes vitrified after warming. However, maturation and cleavage rates after conventional insemination were greater in the EG only group than in the EG+DMSO group. In mature oocytes, survival, cleavage, and blastocyst formation rates after warming showed no significant difference when EG only or EG+DMSO was applied. Furthermore, cleavage and blastocyst formation rates of MII oocytes vitrified using SN2 were increased in both the EG only and EG+DMSO groups. Conclusion A combination of CPAs in oocyte cryopreservation could be formulated according to the oocyte stage. In addition, SN2 may improve the efficiency of vitrification by reducing cryoinjury. PMID:22384414

Europa Ice Floes

NASA Technical Reports Server (NTRS)

1997-01-01

Jupiter's moon Europa, as seen in this image taken June 27, 1996 by NASA's Galileo spacecraft, displays features in some areas resembling ice floes seen in Earth's polar seas. Europa, about the size of Earth's moon, has an icy crust that has been severely fractured, as indicated by the dark linear, curved, and wedged-shaped bands seen here. These fractures have broken the crust into plates as large as 30 kilometers (18.5 miles) across. Areas between the plates are filled with material that was probably icy slush contaminated with rocky debris. Some individual plates were separated and rotated into new positions. Europa's density indicates that it has a shell of water ice thicker than 100 kilometers (about 60 miles), parts of which could be liquid. Currently, water ice could extend from the surface down to the rocky interior, but the features seen in this image suggest that motion of the disrupted icy plates was lubricated by soft ice or liquid water below the surface at the time of disruption. This image covers part of the equatorial zone of Europa and was taken from a distance of 156,000 kilometers (about 96,300 miles) by the Solid-state Imaging Subsystem on the Galileo spacecraft. North is to the right and the sun is nearly directly overhead. The area shown is about 510 by 989 kilometers (310-by-600 miles), and the smallest visible feature is about 1.6 kilometers (1 mile) across.

The Jet Propulsion Laboratory manages the Galileo mission for NASA's Office of Space Science, Washington, DC.

This image and other images and data received from Galileo are posted on the World Wide Web Galileo mission home page at http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http:// www.jpl.nasa.gov/galileo/sepo.

An Ultra-Wideband, Microwave Radar for Measuring Snow Thickness on Sea Ice and Mapping Near-Surface Internal Layers in Polar Firn

NASA Technical Reports Server (NTRS)

Panzer, Ben; Gomez-Garcia, Daniel; Leuschen, Carl; Paden, John; Rodriguez-Morales, Fernando; Patel, Azsa; Markus, Thorsten; Holt, Benjamin; Gogineni, Prasad

2013-01-01

Sea ice is generally covered with snow, which can vary in thickness from a few centimeters to >1 m. Snow cover acts as a thermal insulator modulating the heat exchange between the ocean and the atmosphere, and it impacts sea-ice growth rates and overall thickness, a key indicator of climate change in polar regions. Snow depth is required to estimate sea-ice thickness using freeboard measurements made with satellite altimeters. The snow cover also acts as a mechanical load that depresses ice freeboard (snow and ice above sea level). Freeboard depression can result in flooding of the snow/ice interface and the formation of a thick slush layer, particularly in the Antarctic sea-ice cover. The Center for Remote Sensing of Ice Sheets (CReSIS) has developed an ultra-wideband, microwave radar capable of operation on long-endurance aircraft to characterize the thickness of snow over sea ice. The low-power, 100mW signal is swept from 2 to 8GHz allowing the air/snow and snow/ ice interfaces to be mapped with 5 c range resolution in snow; this is an improvement over the original system that worked from 2 to 6.5 GHz. From 2009 to 2012, CReSIS successfully operated the radar on the NASA P-3B and DC-8 aircraft to collect data on snow-covered sea ice in the Arctic and Antarctic for NASA Operation IceBridge. The radar was found capable of snow depth retrievals ranging from 10cm to >1 m. We also demonstrated that this radar can be used to map near-surface internal layers in polar firn with fine range resolution. Here we describe the instrument design, characteristics and performance of the radar.

Controls of sediment transfers, sedimentary budgets and relief development in cold environments: Results from four catchment systems in Iceland, Swedish Lapland and Finnish Lapland

NASA Astrophysics Data System (ADS)

Beylich, A. A.

2012-04-01

By the combined, longer-term and quantitative recording of relevant denudative slope processes and stream work in four selected catchment systems in sub-arctic oceanic Eastern Iceland (Hrafndalur and Austdalur), arctic-oceanic Swedish Lapland (Latnjavagge) and sub-arctic oceanic Finnish Lapland (Kidisjoki), information on the absolute and relative importance of the different denudative processes is collected. Direct comparison of the four catchment geo-systems (the catchment sizes range from 7 km2 to 23 km2) allows conclusions on major controls of sediment transfers, sedimentary budgets and relief development in theses cold climate environments. To allow direct comparison of the different processes, all mass transfers are calculated as tonnes multiplied by meter per year, i.e. as the product of the annually transferred mass and the corresponding transport distance. Ranking the different processes according to their annual mass transfers shows that stream work dominates over slope denudation. For Hrafndalur (Eastern Iceland) the following order of denudative processes is found after nine years of process studies (2001 - 2010): (1) Fluvial suspended sediment plus bedload transport, (2) Fluvial solute transport, (3) Rock falls plus boulder falls, (4) Chemical slope denudation, (5) Mechanical fluvial slope denudation (slope wash), (6) Creep processes, (7) Avalanches, (8) Debris flows, (9) Translation slides, (10) Deflation. Compared to that, in Austdalur the following ranking is given after fourten years of process studies (1996 - 2010): (1) Fluvial suspended sediment plus bedload transport, (2) Fluvial solute transport, (3) Mechanical fluvial slope denudation (slope wash), (4) Chemical slope denudation, (5) Avalanches, (6) Rock falls plus boulder falls, (7) Creep processes, (8) Debris flows, (9) Deflation, (10) Translation slides. In the Latnjavagge catchment (Swedish Lapland) the ranking is (eleven-years period of studies, 1999 - 2010): (1) Fluvial solute transport, (2) Fluvial suspended sediment plus bedload transport, (3) Rock falls plus boulder falls, (4) Chemical slope denudation, (5) Mechanical fluvial slope denudation (slope wash), (6) Avalanches, (7) Creep processes and solifluction, (8) Slush flows, (9) Debris flows, (10) Translation slides, (11) Deflation. In Kidisjoki (Finnish Lapland) the order of processes, as determined after a nine-years period (2001 - 2010) of geomorphic process studies, is: (1) Fluvial solute transport, (2) Chemical slope denudation, (3) Fluvial suspended sediment plus bedload transport, (4) Mechanical fluvial slope denudation, (5) Creep processes, (6) Avalanches and slush flows, (7) Debris flows and slides, (8) Rock and boulder falls, (9) Deflation. As a result, in all four selected cold climate study areas the intensity of contemporary denudative processes and mass transfers is altogether rather low, which is in opposition to the earlier postulated oppinion of a generally high intensity of geomorphic processes in cold climate environments. A direct comparison of the annual mass transfers summarises that there are differences between process intensities and the relative importance of different denudative processes within the four study areas. The major controls of these detected differences are: (i) Climate: The higher annual precipitation along with the larger number of extreme rainfall events and the higher frequency of snowmelt and rainfall generated peak runoff events in Eastern Iceland as compared to Swedish Lapland and Finnish Lapland lead to higher mass transfers, (ii) Lithology: The low resistance of rhyolites in Hrafndalur causes especially high weathering rates and connected mass transfers in this catchment. Due to the lower resistance of the rhyolites as compared to the basalts found in Austdalur Postglacial modification of the glacially formed relief is clearly further advanced in Hrafndalur as compared to Austdalur, (iii) Relief: The greater steepness of the Icelandic catchments leads to higher mass transfers here as compared to Latnjavagge and Kidisjoki, (iv) Vegetation cover: The significant disturbance of the vegetation cover by human impacts in Easter Iceland causes higher mass transfers (slope wash) whereas restricted sediment availability is a main reason for lower mass transfers in Swedish Lapland and Finnish Lapland. The applied catchment-based approach seems to be effective for analysing sediment budgets and trends of Postglacial relief development in selected study areas with given environmental settings. Direct comparison of investigated catchments will improve possibilities to model relief development as well as possible effects of projected climate change in cold climate environments.

Calibration and Field Deployment of the NSF G-V VCSEL Hygrometer

NASA Astrophysics Data System (ADS)

DiGangi, J. P.; O'Brien, A.; Diao, M.; Hamm, C.; Zhang, Q.; Beaton, S. P.; Zondlo, M. A.

2012-12-01

Cloud formation and dynamics have a significant influence on the Earth's radiative forcing budget, which illustrates the importance of clouds with respect to global climate. Therefore, an accurate understanding of the microscale processes dictating cloud formation is crucial for accurate computer modeling of global climate change. A critical tool for understanding these processes from an airborne platform is an instrument capable of measuring water vapor with both high accuracy and time, thus spatial, resolution. Our work focuses on an open-path, compact, vertical-cavity surface-emitting laser (VCSEL) absorption-based hygrometer, capable of 25 Hz temporal resolution, deployed on the NSF/NCAR Gulfstream-V aircraft platform. The open path nature of our instrument also helps to minimize sampling artifacts. We will discuss our efforts toward achieving within 5% accuracy over 5 orders of magnitude of water vapor concentrations. This involves an intercomparison of five independent calibration methods: ice surface saturators using an oil temperature bath, solvent slush baths (e.g. chloroform/LN2, water/ice), a research-grade frost point hygrometer, static pressure experiments, and Pt catalyzed hydrogen gas. This wide variety of available tools allows us to accurately constrain the calibrant water vapor concentrations both before and after the VCSEL hygrometer sampling chamber. For example, the mixing ratio as measured by research-grade frost point hygrometer after the VCSEL hygrometer agreed within 2% of the mixing ration expected from the water/ice bubbler source before the VCSEL over the temperature range -50°C to 20°C. Finally, due to the compact nature of our instrument, we are able to perform these calibrations simultaneously at the same temperatures (-80°C to 30°C) and pressures (150 mbar to 760 mbar) as sampled ambient air during a flight. This higher accuracy can significantly influence the science utilizing this data, which we will illustrate using preliminary data from our most recent field deployment, the NSF Deep Convective Clouds and Chemistry Experiment in May-June 2012

Warmer and wetter winters: characteristics and implications of an extreme weather event in the High Arctic

NASA Astrophysics Data System (ADS)

Hansen, Brage B.; Isaksen, Ketil; Benestad, Rasmus E.; Kohler, Jack; Pedersen, Åshild Ø.; Loe, Leif E.; Coulson, Stephen J.; Larsen, Jan Otto; Varpe, Øystein

2014-11-01

One predicted consequence of global warming is an increased frequency of extreme weather events, such as heat waves, droughts, or heavy rainfalls. In parts of the Arctic, extreme warm spells and heavy rain-on-snow (ROS) events in winter are already more frequent. How these weather events impact snow-pack and permafrost characteristics is rarely documented empirically, and the implications for wildlife and society are hence far from understood. Here we characterize and document the effects of an extreme warm spell and ROS event that occurred in High Arctic Svalbard in January-February 2012, during the polar night. In this normally cold semi-desert environment, we recorded above-zero temperatures (up to 7 °C) across the entire archipelago and record-breaking precipitation, with up to 98 mm rainfall in one day (return period of >500 years prior to this event) and 272 mm over the two-week long warm spell. These precipitation amounts are equivalent to 25 and 70% respectively of the mean annual total precipitation. The extreme event caused significant increase in permafrost temperatures down to at least 5 m depth, induced slush avalanches with resultant damage to infrastructure, and left a significant ground-ice cover (˜5-20 cm thick basal ice). The ground-ice not only affected inhabitants by closing roads and airports as well as reducing mobility and thereby tourism income, but it also led to high starvation-induced mortality in all monitored populations of the wild reindeer by blocking access to the winter food source. Based on empirical-statistical downscaling of global climate models run under the moderate RCP4.5 emission scenario, we predict strong future warming with average mid-winter temperatures even approaching 0 °C, suggesting increased frequency of ROS. This will have far-reaching implications for Arctic ecosystems and societies through the changes in snow-pack and permafrost properties.

A closer look at Chaos on Europa

NASA Technical Reports Server (NTRS)

1998-01-01

This mosaic of the Conamara Chaos region on Jupiter's moon, Europa, clearly indicates relatively recent resurfacing of Europa's surface. Irregularly shaped blocks of water ice were formed by the break up and movement of the existing crust. The blocks were shifted, rotated, and even tipped and partially submerged within a mobile material that was either liquid water, warm mobile ice, or an ice and water slush. The presence of young fractures cutting through this region indicates that the surface froze again into solid, brittle ice.

The background image in this picture was taken during Galileo's sixth orbit of Jupiter in February, 1997. Five very high resolution images which were taken during the spacecraft's twelfth orbit in December, 1997 provide an even closer look at some of the details. This mosaic shows some of the high resolution data inset into the context of this tumultuous region.

North is to the top of the picture, and the sun illuminates the scene from the east (right). The picture, centered at 9 degrees north latitude and 274 degrees west longitude, covers an area approximately 35 by 50 kilometers (20 by 30 miles). The finest details visible in the very high resolution insets are about 20 meters (22 yards) across, and in the background image, 100 meters (110 yards) across. The insets were taken on December 16, 1997, at ranges as close as 880 kilometers (550 miles) by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft.

The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at URL http://www.jpl.nasa.gov/galileo/sepo

Tidally Heated Terrestrial Exoplanets

NASA Astrophysics Data System (ADS)

Henning, Wade Garrett

This work models the surface and internal temperatures for hypothetical terrestrial planets in situations involving extreme tidal heating. The feasibility of such planets is evaluated in terms of the orbital perturbations that may give rise to them, their required proximity to a hoststar, and the potential for the input tidal heating to cause significant partial melting of the mantle. Trapping terrestrial planets into 2:1 resonances with migrating Hot Jupiters is considered as a reasonable way for Earth-like worlds to both maintain high eccentricities and to move to short enough orbital periods (1-20 days) for extreme tidal heating to occur. Secular resonance and secular orbital perturbations may support moderate tidal heating at a low equilibrium eccentricity. At orbital periods below 10-30 days, with eccentricities from 0.01 to 0.1, tidal heat may greatly exceed radiogenic heat production. It is unlikely to exceed insolation, except when orbiting very low luminosity hosts, and thus will have limited surface temperature expression. Observations of such bodies many not be able to detect tidal surface enhancements given a few percent uncertainty in albedo, except on the nightside of spin synchronous airless objects. Otherwise detection may occur via spectral detection of hotspots or high volcanic gas concentrations including sulfur dioxide and hydrogen sulfide. The most extreme cases may be able to produce magma oceans, or magma slush mantles with up to 40-60% melt fractions. Tides may alter the habitable zones for smaller red dwarf stars, but are generally detrimental. Multiple viscoelastic models, including the Maxwell, Voigt-Kelvin, Standard Anelastic Solid, and Burgers rheologies are explored and applied to objects such as Io and the super-Earth planet GJ 876d. The complex valued Love number for the Burgers rheology is derived and found to be a useful improvement when modeling the low temperature behavior of tidal bodies, particularly during low eccentricity excursions. Viscoelastic solutions for GJ 876d are typical of extreme short period high eccentricity objects with tidal-convectiveequilibrium heat rates between ˜10,000 to 500,000 terawatts.

Robotic kidney transplantation with regional hypothermia: a step-by-step description of the Vattikuti Urology Institute-Medanta technique (IDEAL phase 2a).

PubMed

Menon, Mani; Sood, Akshay; Bhandari, Mahendra; Kher, Vijay; Ghosh, Prasun; Abaza, Ronney; Jeong, Wooju; Ghani, Khurshid R; Kumar, Ramesh K; Modi, Pranjal; Ahlawat, Rajesh

2014-05-01

We recently reported on preclinical and feasibility studies (Innovation, Development, Exploration, Assessment, Long-term study [IDEAL] phase 0-1) of the development of robotic kidney transplantation (RKT) with regional hypothermia. This paper presents the IDEAL phase 2a studies of technique development. To describe the technique of RKT with regional hypothermia developed at two tertiary care institutions (Vattikuti Urology Institute and Medanta Hospital). We report on the safety profile and early graft function in these patients. This is a prospective study of 50 consecutive patients who underwent live-donor RKT at Medanta Hospital following a 3-yr planning/simulation phase at the Vattikuti Urology Institute. Demographic details, and perioperative and postoperative outcomes are reported for the initial 25 recipients who have completed a minimum 6-mo follow-up. Positioning and port placement were similar to that used for robotic radical prostatectomy. Allograft cooling was achieved by ice slush delivered through a GelPOINT device. The accompanying video details the operative technique. The primary outcome was posttransplant graft function. Secondary outcomes included technical success or failure and complication rates. Fifty patients underwent RKT successfully, 7 in the phase 1 and 43 in the phase 2 stages of the study. For the initial 25 patients, mean console, warm ischemia, arterial, and venous anastomotic times were 135, 2.4, 12, and 13.4 min, respectively. All grafts were cooled to 18-20 °C with no change in core body temperature. All grafts functioned immediately posttransplant and the mean serum creatinine level at discharge was 1.3mg/dl (range: 0.8-3.1mg/dl). No patient developed anastomotic leaks, wound complications, or wound infections. At 6-mo of follow-up, no patient had developed a lymphocele detected on CT scanning. Two patients underwent re-exploration, and one patient died of congestive heart failure (1.5 mo posttransplant). RKT with regional hypothermia is safe and reproducible when performed by a team skilled in robotic surgery. RKT is safe and effective when performed by surgeons experienced in robotic techniques. Copyright © 2013 European Association of Urology. Published by Elsevier B.V. All rights reserved.

Slush Fund: The Multiphase Nature of Oceanic Ices and Its Role in Shaping Europa's Icy Shell

NASA Astrophysics Data System (ADS)

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

2017-12-01

The role of Europa's ice shell in mediating ocean-surface interaction, constraining potential habitability of the underlying hydrosphere, and dictating the surface morphology of the moon is discussed extensively in the literature, yet the dynamics and characteristics of the shell itself remain largely unconstrained. Some of the largest unknowns arise from underrepresented physics and varying a priori assumptions built into the current ice shell models. Here we modify and apply a validated one-dimensional reactive transport model designed to simulate the formation and evolution of terrestrial sea ice to the Europa environment. The top-down freezing of sea ice due to conductive heat loss to the atmosphere is akin to the formation of the Jovian moon's outer ice shell, albeit on a different temporal and spatial scale. Nevertheless, the microscale physics that govern the formation of sea ice on Earth (heterogenous solidification leading to brine pockets and channels, multiphase reactive transport phenomena, gravity drainage) likely operate in a similar manner at the ice-ocean interface of Europa, dictating the thermal, chemical, and mechanical properties of the ice shell. Simulations of the European ice-ocean interface at different stages during the ice shell's evolution are interpolated to produce vertical profiles of temperature, salinity, solid fraction, and eutectic points throughout the entire shell. Additionally, the model is coupled to the equilibrium chemistry package FREZCHEM to investigate the impact a diverse range of putative European ocean chemistries has on ice shell properties. This method removes the need for a priori assumptions of impurity entrainment rates and ice shell properties, thus providing a first principles constraint on the stratigraphic characteristics of a simulated European ice shell. These insights have the potential to improve existing estimates for the onset of solid state convection, melt lens formation due to eutectic melting, ice shell thickness, and ocean-surface interaction rates. Moreover, this work aims to shed light on the important role microscale physics plays in determining the macroscale properties of icy worlds by highlighting and adapting successful multiphase reactive transport sea ice models utilized in large scale Earth systems science simulations.

Slush Fund: Modeling the Multiphase Physics of Oceanic Ices

NASA Astrophysics Data System (ADS)

Buffo, J.; Schmidt, B. E.

2016-12-01

The prevalence of ice interacting with an ocean, both on Earth and throughout the solar system, and its crucial role as the mediator of exchange between the hydrosphere below and atmosphere above, have made quantifying the thermodynamic, chemical, and physical properties of the ice highly desirable. While direct observations of these quantities exist, their scarcity increases with the difficulty of obtainment; the basal surfaces of terrestrial ice shelves remain largely unexplored and the icy interiors of moons like Europa and Enceladus have never been directly observed. Our understanding of these entities thus relies on numerical simulation, and the efficacy of their incorporation into larger systems models is dependent on the accuracy of these initial simulations. One characteristic of seawater, likely shared by the oceans of icy moons, is that it is a solution. As such, when it is frozen a majority of the solute is rejected from the forming ice, concentrating in interstitial pockets and channels, producing a two-component reactive porous media known as a mushy layer. The multiphase nature of this layer affects the evolution and dynamics of the overlying ice mass. Additionally ice can form in the water column and accrete onto the basal surface of these ice masses via buoyancy driven sedimentation as frazil or platelet ice. Numerical models hoping to accurately represent ice-ocean interactions should include the multiphase behavior of these two phenomena. While models of sea ice have begun to incorporate multiphase physics into their capabilities, no models of ice shelves/shells explicitly account for the two-phase behavior of the ice-ocean interface. Here we present a 1D multiphase model of floating oceanic ice that includes parameterizations of both density driven advection within the `mushy layer' and buoyancy driven sedimentation. The model is validated against contemporary sea ice models and observational data. Environmental stresses such as supercooling and melting events will be discussed for terrestrial ice. The impact of fluid motion within the mushy layer on nutrient transport and habitability will be discussed. Results from the model's application to icy moon environments will be presented, highlighting ice shell composition, thickness, thermodynamics, and role in potential habitability.

Determination of the δ15N of nitrate in water; RSIL lab code 2899

USGS Publications Warehouse

Coplen, Tyler B.; Qi, Haiping; Revesz, Kinga; Casciotti, Karen; Hannon, Janet E.

2007-01-01

The purpose of the Reston Stable Isotope Laboratory (RSIL) lab code 2899 is to determine the δ15N of nitrate (NO3-) in water. The δ15N of the dissolved NO3- is analyzed by conversion of the NO3- to nitrous oxide (N2O), which serves as the analyte for mass spectrometry. A culture of denitrifying bacteria is used in the enzymatic conversion of the NO3- to N2O, which follows the pathway shown in equation 1: NO3- → NO2- → NO → 1/2 N2O (1) Because the bacteria Pseudomonas aureofaciens lack N2O reductive activity, the reaction stops at N2O, unlike the typical denitrification reaction that goes to N2. After several hours, the conversion is complete, and the N2O is extracted from the vial, separated from volatile organic vapor and water vapor by an automated -65 °C isopropanol-slush trap, a Nafion drier, a CO2 and water removal unit (Costech #021020 carbon dioxide absorbent with Mg(ClO4)2), and trapped in a small-volume trap immersed in liquid nitrogen with a modified Finnigan MAT (now Thermo Scientific) GasBench 2 introduction system. After the N2O is released, it is further purified by gas chromatography before introduction to the isotope-ratio mass spectrometer (IRMS). The IRMS is a Thermo Scientific Delta V Plus continuous flow IRMS (CF-IRMS). It has a universal triple collector, consisting of two wide cups with a narrow cup in the middle; it is capable of simultaneously measuring mass/charge (m/z) of the N2O molecule 44, 45, and 46. The ion beams from these m/z values are as follows: m/z = 44 = N2O = 14N14N16O; m/z = 45 = N2O = 14N15N16O or 14N14N17O; m/z = 46 = N2O = 14N14N18O. The 17O contributions to the m/z 44 and m/z 45 ion beams are accounted for before δ15N values are reported.

Performance evaluation of the national early warning system for shallow landslides in Norway

NASA Astrophysics Data System (ADS)

Dahl, Mads-Peter; Piciullo, Luca; Devoli, Graziella; Colleuille, Hervé; Calvello, Michele

2017-04-01

As a consequence of the increased number of rainfall-and snowmelt-induced landslides (debris flows, debris slides, debris avalanches and slush flows) occurring in Norway, a national landslide early warning system (EWS) has been developed for monitoring and forecasting the hydro-meteorological conditions potentially necessary of triggering slope failures. The system, operational since 2013, is managed by the Norwegian Water Resources and Energy Directorate (NVE) and has been designed in cooperation with the Norwegian Public Road Administration (SVV), the Norwegian National Rail Administration (JBV) and the Norwegian Meteorological Institute (MET). Decision-making in the EWS is based upon hazard threshold levels, hydro-meteorological and real-time landslide observations as well as landslide inventory and susceptibility maps. Hazard threshold levels have been obtained through statistical analyses of historical landslides and modelled hydro-meteorological parameters. Daily hydro-meteorological conditions such as rainfall, snowmelt, runoff, soil saturation, groundwater level and frost depth have been derived from a distributed version of the hydrological HBV-model. Two different landslide susceptibility maps are used as supportive data in deciding daily warning levels. Daily alerts are issued throughout the country considering variable warning zones. Warnings are issued once per day for the following 3 days with an update possibility later during the day according to the information gathered by the monitoring variables. The performance of the EWS has been evaluated applying the EDuMaP method. In particular, the performance of warnings issued in Western Norway, in the period 2013-2014 has been evaluated using two different landslide datasets. The best performance is obtained for the smallest and more accurate dataset. Different performance results may be observed as a function of changing the landslide density criterion, Lden(k), (i.e., thresholds considered to differentiate among classes of landslide events) used as an input parameter within the EDuMaP method. To investigate this issue, a parametric analysis has been conducted; the results of the analysis show clear differences among computed performances when absolute or relative landslide density criteria are considered.

Why is intracellular ice lethal? A microscopical study showing evidence of programmed cell death in cryo-exposed embryonic axes of recalcitrant seeds of Acer saccharinum

PubMed Central

Wesley-Smith, James; Walters, Christina; Pammenter, N. W.

2015-01-01

Background and Aims Conservation of the genetic diversity afforded by recalcitrant seeds is achieved by cryopreservation, in which excised embryonic axes (or, where possible, embryos) are treated and stored at temperatures lower than −180 °C using liquid nitrogen. It has previously been shown that intracellular ice forms in rapidly cooled embryonic axes of Acer saccharinum (silver maple) but this is not necessarily lethal when ice crystals are small. This study seeks to understand the nature and extent of damage from intracellular ice, and the course of recovery and regrowth in surviving tissues. Methods Embryonic axes of A. saccharinum, not subjected to dehydration or cryoprotection treatments (water content was 1·9 g H2O g−1 dry mass), were cooled to liquid nitrogen temperatures using two methods: plunging into nitrogen slush to achieve a cooling rate of 97 °C s−1 or programmed cooling at 3·3 °C s−1. Samples were thawed rapidly (177 °C s−1) and cell structure was examined microscopically immediately, and at intervals up to 72 h in vitro. Survival was assessed after 4 weeks in vitro. Axes were processed conventionally for optical microscopy and ultrastructural examination. Key Results Immediately following thaw after cryogenic exposure, cells from axes did not show signs of damage at an ultrastructural level. Signs that cells had been damaged were apparent after several hours of in vitro culture and appeared as autophagic decomposition. In surviving tissues, dead cells were sloughed off and pockets of living cells were the origin of regrowth. In roots, regrowth occurred from the ground meristem and procambium, not the distal meristem, which became lethally damaged. Regrowth of shoots occurred from isolated pockets of surviving cells of peripheral and pith meristems. The size of these pockets may determine the possibility for, the extent of and the vigour of regrowth. Conclusions Autophagic degradation and ultimately autolysis of cells following cryo-exposure and formation of small (0·2–0·4 µm) intracellular ice crystals challenges current ideas that ice causes immediate physical damage to cells. Instead, freezing stress may induce a signal for programmed cell death (PCD). Cells that form more ice crystals during cooling have faster PCD responses. PMID:25808653

Determination of the δ15N of nitrate in solids; RSIL lab code 2894

USGS Publications Warehouse

Coplen, Tyler B.; Qi, Haiping; Revesz, Kinga; Casciotti, Karen; Hannon, Janet E.

2007-01-01

The purpose of the Reston Stable Isotope Laboratory (RSIL) lab code 2894 is to determine the δ15N of nitrate (NO3-) in solids. The nitrate fraction of the nitrogen species is dissolved by water (called leaching) and can be analyzed by the bacterial method covered in RSIL lab code 2899. After leaching, the δ15N of the dissolved NO3- is analyzed by conversion of the NO3- to nitrous oxide (N2O), which serves as the analyte for mass spectrometry. A culture of denitrifying bacteria is used in the enzymatic conversion of NO3- to N2O, which follows the pathway shown in equation 1: NO3- → NO2- → NO → 1/2 N2O (1) Because the bacteria Pseudomonas aureofaciens lack N2O reductive activity, the reaction stops at N2O, unlike the typical denitrification reaction that goes to N2. After several hours, the conversion is complete, and the N2O is extracted from the vial, separated from volatile organic vapor and water vapor by an automated -65 °C isopropanol-slush trap, a Nafion drier, a CO2 and water removal unit (Costech #021020 carbon dioxide absorbent with Mg(ClO4)2), and trapped in a small-volume trap immersed in liquid nitrogen with a modified Finnigan MAT (now Thermo Scientific) GasBench 2 introduction system. After the N2O is released, it is further purified by gas chromatography before introduction to the isotope-ratio mass spectrometer (IRMS). The IRMS is a Thermo Scientific Delta V Plus continuous flow IRMS (CF-IRMS). It has a universal triple collector, consisting of two wide cups with a narrow cup in the middle; it is capable of simultaneously measuring mass/charge (m/z) of the N2O molecule 44, 45, and 46. The ion beams from these m/z values are as follows: m/z = 44 = N2O = 14N14N16O; m/z = 45 = N2O = 14N15N16O or 14N14N17O; m/z = 46 = N2O = 14N14N18O. The 17O contributions to the m/z 44 and m/z 45 ion beams are accounted for before δ15N values are reported.

Determination of the δ15N and δ18O of nitrate in water; RSIL lab code 2900

USGS Publications Warehouse

Coplen, Tyler B.; Qi, Haiping; Revesz, Kinga; Casciotti, Karen; Hannon, Janet E.

2007-01-01

The purpose of the Reston Stable Isotope Laboratory (RSIL) lab code 2900 is to determine the δ15N and δ18O of nitrate (NO3-) in water. The δ15N and δ18O of the dissolved NO3- are analyzed by converting the NO3- to nitrous oxide (N2O), which serves as the analyte for mass spectrometry. A culture of denitrifying bacteria is used in the enzymatic conversion of the NO3- to N2O, which follows the pathway shown in equation 1: NO3- → NO2- → NO → 1/2 N2O (1) Because the bacteria Pseudomonas aureofaciens lack N2O reductive activity, the reaction stops at N2O, unlike the typical denitrification reaction that goes to N2. After several hours, the conversion is complete, and the N2O is extracted from the vial, separated from volatile organic vapor and water vapor by an automated -65 °C isopropanol-slush trap, a Nafion drier, a CO2 and water removal unit (Costech #021020 carbon dioxide absorbent with Mg(ClO4)2), and trapped in a small-volume trap immersed in liquid nitrogen with a modified Finnigan MAT (now Thermo Scientific) GasBench 2 introduction system. After the N2O is released, it is further purified by gas chromatography before introduction to the isotope-ratio mass spectrometer (IRMS). The IRMS is a Thermo Scientific Delta V Plus continuous flow IRMS (CF-IRMS). It has a universal triple collector, consisting of two wide cups with a narrow cup in the middle; it is capable of simultaneously measuring mass/charge (m/z) of the N2O molecule 44, 45, and 46. The ion beams from these m/z values are as follows: m/z = 44 = N2O = 14N14N16O; m/z = 45 = N2O = 14N15N16O or 14N14N17O; m/z = 46 = N2O = 14N14N18O. The 17O contributions to the m/z 44 and m/z 45 ion beams are accounted for before δ15N values are reported.

Scrambled Ice

NASA Technical Reports Server (NTRS)

1998-01-01

This complex area on the side of Europa which faces away from Jupiter shows several types of features which are formed by disruptions of Europa's icy crust. North is to the top of the image, taken by NASA's Galileo spacecraft, and the Sun illuminates the surface from the left. The prominent wide, dark bands are up to 20 kilometers (12 miles) wide and over 50 kilometers (30 miles) long. They are believed to have formed when Europa's icy crust fractured, separated and filled in with darker, 'dirtier' ice or slush from below. A relatively rare type of feature on Europa is the 15-kilometer-diameter (9.3-mile) impact crater in the lower left corner. The small number of impact craters on Europa's surface is an indication of its relatively young age. A region of chaotic terrain south of this impact crater contains crustal plates which have broken apart and rafted into new positions. Some of these 'ice rafts' are nearly 1 kilometer (about half a mile) across. Other regions of chaotic terrain are visible and indicate heating and disruption of Europa's icy crust from below. The youngest features in this scene are the long, narrow cracks in the ice which cut across all other features. One of these cracks is about 30 kilometers (18 miles) to the right of the impact crater and extends for hundreds of miles from the top to the bottom of the image.

The image, centered near 23 degrees south latitude and 179 degrees longitude, covers an area about 240 by 215 kilometers (150 by 130 miles) across. The finest details that can be discerned in this picture are about 460 meters (500 yards) across. The image was taken as Galileo flew by Europa on March 29, 1998. The image was taken by the onboard solid state imaging system camera from an altitude of 23,000 kilometers (14,000 miles).

The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at URL http://www.jpl.nasa.gov/galileo/sepo

Micro-investigation of EPICA Dome C bottom ice: evidence of long term in situ processes involving acid-salt interactions, mineral dust, and organic matter

NASA Astrophysics Data System (ADS)

de Angelis, M.; Tison, J.-L.; Morel-Fourcade, M.-C.; Susini, J.

2013-10-01

The EPICA Dome C ice core (EDC) reached a final depth of 3260 m, at a maximum height of about 15 m above the ice-bedrock interface in December 2004. We present here data gained from a detailed investigation of selected samples of the deeper part of the core located below 3200 m and referred to as bottom ice. This part of the core has been poorly investigated so far mainly because there are significant challenges in interpreting paleo-records that were very likely modified by long term in situ processes. Our study combines high resolution ion chromatography, high resolution synchrotron X-Ray micro-fluorescence (micro XRF), scanning, and transmission electron microscopy. Our aim was to identify the long term physico-chemical processes at work close to the bedrock, to determine how they have altered the initial registers, and, ultimately to extract information on the very ancient Antarctic environment. The ubiquitous presence of nanometer iron oxide crystals at the surface of wind-borne dust aggregates containing also large amount of organic matter raises the possibility that the consolidation of windborne dust clusters formed during ice recrystallization could be related to microbial iron reduction and, thus, to the progressive reactivation of dormant bacterial activity in warming ice. Inclusions of size and number density increasing with depth observed in the 12 last meters (3248-3260 m) contain liquid and solid species, among them marine biogenic acids, numerous wind-borne dust aggregates and clusters of large reversible calcium carbonate particles precipitated once the inclusion was formed and often covered by secondary gypsum. The refreezing of slush lenses is discussed as a potential cause of the formation of such heterogeneous and complex mixtures. In addition to the very fine micrometer size minerals windborne from extra-Antarctic continental sources and often accreted in large aggregates, single medium size particles (a few to ca 20 μm and among them organic debris) are commonly encountered. Their size, surface shape, and mineralogy suggest that aerosol transport from Antarctic ice-free areas played a significant role at the time EDC bottom ice was formed. Concentrations and concentration ratios of biogenic sulfur species also advocate for the strengthening of peri-Antarctic meteorological patterns that favor the inland penetration of disturbed flow carrying local material. Very large well preserved mineral particles several tens of micrometers in diameter, and biotope relics in deeper ice close to 3260 m likely come from the sub-glacial environment.

Determination of the δ15N and δ18O of nitrate in solids; RSIL lab code 2897

USGS Publications Warehouse

Coplen, Tyler B.; Qi, Haiping; Revesz, Kinga; Casciotti, Karen; Hannon, Janet E.

2007-01-01

The purpose of the Reston Stable Isotope Laboratory (RSIL) lab code 2897 is to determine the δ15N and δ18O of nitrate (NO3-) in solids. The NO3- fraction of the nitrogen species is dissolved by water (called leaching) and can be analyzed by the bacterial method covered in RSIL lab code 2900. After leaching, the δ15N and δ18O of the dissolved NO3- is analyzed by conversion of the NO3- to nitrous oxide (N2O), which serves as the analyte for mass spectrometry. A culture of denitrifying bacteria is used in the enzymatic conversion of NO3- to N2O, which follows the pathway shown in equation 1: NO3- → NO2- → NO → 1/2 N2O (1) Because the bacteria Pseudomonas aureofaciens lack N2O reductive activity, the reaction stops at N2O, unlike the typical denitrification reaction that goes to N2. After several hours, the conversion is complete, and the N2O is extracted from the vial, separated from volatile organic vapor and water vapor by an automated -65 °C isopropanol-slush trap, a Nafion drier, a CO2 and water removal unit (Costech #021020 carbon dioxide absorbent with Mg(ClO4)2), and trapped in a small-volume trap immersed in liquid nitrogen with a modified Finnigan MAT (now Thermo Scientific) GasBench 2 introduction system. After the N2O is released, it is further purified by gas chromatography before introduction to the isotope-ratio mass spectrometer (IRMS). The IRMS is a Thermo Scientific Delta V Plus continuous flow IRMS (CF-IRMS). It has a universal triple collector, consisting of two wide cups with a narrow cup in the middle; it is capable of simultaneously measuring mass/charge (m/z) of the N2O molecule 44, 45, and 46. The ion beams from these m/z values are as follows: m/z = 44 = N2O = 14N14N16O; m/z = 45 = N2O = 14N15N16O or 14N14N17O; m/z = 46 = N2O = 14N14N18O. The 17O contributions to the m/z 44 and m/z 45 ion beams are accounted for before δ15N values are reported.

Why is intracellular ice lethal? A microscopical study showing evidence of programmed cell death in cryo-exposed embryonic axes of recalcitrant seeds of Acer saccharinum.

PubMed

Wesley-Smith, James; Walters, Christina; Pammenter, N W; Berjak, Patricia

2015-05-01

Conservation of the genetic diversity afforded by recalcitrant seeds is achieved by cryopreservation, in which excised embryonic axes (or, where possible, embryos) are treated and stored at temperatures lower than -180 °C using liquid nitrogen. It has previously been shown that intracellular ice forms in rapidly cooled embryonic axes of Acer saccharinum (silver maple) but this is not necessarily lethal when ice crystals are small. This study seeks to understand the nature and extent of damage from intracellular ice, and the course of recovery and regrowth in surviving tissues. Embryonic axes of A. saccharinum, not subjected to dehydration or cryoprotection treatments (water content was 1·9 g H2O g(-1) dry mass), were cooled to liquid nitrogen temperatures using two methods: plunging into nitrogen slush to achieve a cooling rate of 97 °C s(-1) or programmed cooling at 3·3 °C s(-1). Samples were thawed rapidly (177 °C s(-1)) and cell structure was examined microscopically immediately, and at intervals up to 72 h in vitro. Survival was assessed after 4 weeks in vitro. Axes were processed conventionally for optical microscopy and ultrastructural examination. Immediately following thaw after cryogenic exposure, cells from axes did not show signs of damage at an ultrastructural level. Signs that cells had been damaged were apparent after several hours of in vitro culture and appeared as autophagic decomposition. In surviving tissues, dead cells were sloughed off and pockets of living cells were the origin of regrowth. In roots, regrowth occurred from the ground meristem and procambium, not the distal meristem, which became lethally damaged. Regrowth of shoots occurred from isolated pockets of surviving cells of peripheral and pith meristems. The size of these pockets may determine the possibility for, the extent of and the vigour of regrowth. Autophagic degradation and ultimately autolysis of cells following cryo-exposure and formation of small (0·2-0·4 µm) intracellular ice crystals challenges current ideas that ice causes immediate physical damage to cells. Instead, freezing stress may induce a signal for programmed cell death (PCD). Cells that form more ice crystals during cooling have faster PCD responses. Published by Oxford University Press on behalf of the Annals of Botany Company 2015. This work is written by (a) US Government employee(s) and is in the public domain in the US.

Targeting Autotrophic and Lithotrophic Microorganisms from Fumarolic Ice Caves of Mt. Erebus, Antarctica

NASA Astrophysics Data System (ADS)

Anitori, R.; Davis, R.; Connell, L.; Kelley, M.; Staudigel, H.; Tebo, B. M.

2011-12-01

Terrestrial and aquatic volcanic oligotrophic environments can host microorganisms that obtain their energy from reduced inorganic chemicals present in volcanic rocks and soils. We sampled basaltic rock from terrestrial Dark Oligotrophic Volcanic Ecosystems (DOVEs) located in two fumarole ice caves, Warren and Warren West, located near the summit of Mt. Erebus, Antarctica. For reference, we sampled a similar cave, Harry's Dream, which receives continuous light during the Austral summer. We report here culturing data for bacterial and eukaryotic microbes from rocky soils in these caves when targeting lithotrophic organisms using media containing reduced inorganic compounds (Mn2+, Fe2+, NH4+). In addition, to test for the possible presence of inorganic carbon fixation, we screened samples for the ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) gene. Culturing of soil samples on media targeting both autotrophs and heterotrophs yielded a diverse collection of generally slow-growing colonies of bacteria (majority), fungi and non-fungal eukaryotes. Manganese(II)-oxidizing colonies were identified in Warren and Harry's Dream, and these exhibited two colony morphotypes upon subculturing. Sequencing of the PCR amplified 16S rRNA gene identified a bacterium distantly related to Pseudonocardia sp., a genus with known manganese oxidizers. Other bacteria enriched included members of the Actinobacteria, Alphaproteobacteria and Betaproteobacteria. There was a low diversity in cultured eukaryotes representing several potential undescribed species (Geomyces sp., Penicillium sp.) and isolates that may represent alternate, previously undescribed habitats and forms (Psilolechia leprosa, Alternaria alternata). One Warren isolate was a 99% 16S rRNA match to the N2 fixer Bradyrhizobium sp.; when inoculated into liquid medium specific for N2 fixers, growth was maintained upon subculture. Putative iron oxidizers were also enriched from the two DOVE caves, using slush agar iron and O2 gradient tubes. Some of the original soil isolates grown on agar without organic C grew upon subculturing into liquid medium, providing evidence for the successful enrichment of cave autotrophs. Further evidence for autotrophy was the identification of genes for the RuBisCO large subunit gene, suggesting the existence of carbon fixation via the Calvin-Benson cycle. PCR amplification was observed for the type I (cbbL) gene, but not using primers specific for the type II (cbbM) RuBisCO gene. Phylogenetic trees placed the amplified sequences in a monophyletic group deeply rooted in the 'red-like' clade within the cbbL group. Our culture-based exploration of the Mt. Erebus ice caves provides evidence for the presence of litho/autotrophic microorganisms that may be utilizing inorganic energy sources in the volcanic rocks. These results provide a novel view of life in the dark biosphere in deep volcanic settings, and augment studies of seafloor or terrestrial microbial communities in similar extreme volcanic environments.

The research of arsenic existence and action in rivers of Armenia.

NASA Astrophysics Data System (ADS)

Khachiyan, Diana

2010-05-01

In Armenia, to the negative processes connected with global climate changes in the scope of the whole Earth, put in local processes, which are consequences of very ungrateful ecological situation. Today Armenia does not have either strategy or plan of how to adapt to the changes of the environment. Industrial and domestic refuse waste waters of cities and settlements, located near rivers, frequently, without preliminary cleaning, throw out in the river water. In addition, waters of Armenian rivers that used for drinking, irrigation in agriculture, also used in technological processes and industry. For example, one of the factors which have huge destructive impact on the nature of Armenia is the mining and metallurgical field of the industry. In the process of enrichment different chemical compounds are used. Most of industries do not have private cleaning stations. Wastes of industries are concentrated in temporary tailing repositories and then toxic slush overflows out of the tailing repositories will get to rivers. Typical example of that is the river Vokchi. The aim of our research is to monitor arsenic concentrations in natural water of Armenia for the years 2007-2008. For the fulfillment of such work on high level, starting from the selection of tests and ending by working with findings, there is a need of contemporary apparatus, certified clear chemical reagent and materials. Center For Ecological Noosphere Studies of National Academy of Sciences RA is the participant of international project "South Caucasus rivers monitoring " by the program of NATO-OSCE "Science for peace". This appeared a reason to solve problems of accordance to international standards. Expeditionary group preliminary has defined some points of tests selection and selected specimens of river water by means of special apparatus. Chemical analysis of water specimens, which were selected on the above mentioned contaminated territories, fulfilled in analytical laboratory by using the method of electrotermical atomization of atomic absorption spectrometry. The advantage of this method is high accuracy and the possibility to determine different forms of heavy metals (strong mobile water soluble, mobile acid soluble etc.) Subsequently, dependence of changes diagrams of arsenic concentration (ppb) from the time of tests selection (months) from 13 points of rivers of Armenia has built. According to our monitoring, the dependence of changes of arsenic concentration in river water from industrial and domestic refuse objects was observed, also observed depending on year seasons. As known, arsenic toxicity depends on its concentration as in dissolved forms as in suspended condition. We have found that concentrations of dissolved forms of arsenic, practically equals to its total concentration. Basic priority of our research is an observation and understanding of arsenic ecological chemistry, physico-chemical forms of its existence in natural waters of Armenia. Poisoned soil, water and air, lost health of people - such is the price of the development of rough economy of Armenia; such is the price of profit of transnational corporations.

The Story of the Nuclear Rocket: Back to the Future

NASA Astrophysics Data System (ADS)

Dewar, James A.

2002-01-01

The United States had a nuclear rocket development program from 1955-1973 called Project Rover/NERVA. Twenty reactor tests demonstrated conclusively the superiority, flexibility and reliability of nuclear rocket engines over their chemical counterparts. This paper surveys the technical accomplishments from that perspective, to help illustrate why many call for the program's reestablishment. Most focus on the large NERVA, but this review will consider the little known Small Nuclear Engine. KIWI-B1B was one of the first tests in which nuclear rockets demonstrated their superiority. It ejected its core as it rose to 1000MW (a megawatt equals 50 pounds of thrust). This seems contradictory, how can a `failure' demonstrate superiority? Precisely in this: the reactor remained controllable going to and from 1000MW, still ejecting its core, but still turning out power. That gave insurance to a mission. A solid or liquid chemical engine suffering similar damage would likely shutdown or blow up. KIWI-TNT and Phoebus-1A had planned and unplanned accidents. That verified the safety of nuclear engines in launch operations. NRX/EST and XE-Prime proved they could startup reliably under their own power in a simulated space environment and change power without loss of specific impulse or control, from 20MW to 1000MW and back. That gave flexibility for mid-course corrections, maneuvering between orbits or breaking into orbit. Pewee and the Nuclear Furnace tested fuels to achieve 10 hours of engine operation with 60 recycles (stops and starts). That meant an engine could perform multiple missions. Work started on fuels promising1000 seconds of specific impulse. That meant increased power and payload capacity and speed. This contrasts with the 450 seconds of LOX/LH2. The NERVA of 1971 would be 1500MW, with 10/60 capability and 825 seconds of a specific impulse. Later generation NERVAs would be in excess of 1000 seconds, 3000MW and 10/60. The Nixon Administration cancelled it in 1971. After its demise, the Small Nuclear Engine appeared for unmanned missions. To fit in the space shuttle's 15 by 60 foot cargo bay, the 10 foot long engine would be 400MW, weigh 5600 pounds and use slush hydrogen. That left 50 feet and almost 60,000 pounds for the tank, propellant and payload that could vary in size, but it was nominally 5 tons. It would cost 500 million (in1972 dollars) and take a decade to develop. It had NERVA's operating characteristics, but subsequent generation systems envisioned longer engine life and recycle capability and specific impulses of 1000+ seconds. Nixon ended this in 1973. By reconsidering it instead of a nuclear electric engine that serves only space science, the nation could gain a fast, powerful system that would radically change most future unmanned space missions. With its recycle capability, a single engine could ferry large scientific payloads swiftly throughout the solar system. Yet it also could propel heavy national security and commercial payloads to geo-synchronous orbit. NASA might even offer a satellite retrieval service. Thus, one lesson is clear: it is 1960s era technology, but the Small Engine is not obsolete. If developed, it would serve not just one, but three users yet have growth potential for decades for an ever more expansive space program.

Transfer Kinetics at the Aqueous/Non-Aqueous Phase Liquid Interface. A Statistical Mechanic Approach

NASA Astrophysics Data System (ADS)

Doss, S. K.; Ezzedine, S.; Ezzedine, S.; Ziagos, J. P.; Hoffman, F.; Gelinas, R. J.

2001-05-01

Many modeling efforts in the literature use a first-order, linear-driving-force model to represent the chemical dissolution process at the non-aqueous/aqueous phase liquid (NAPL/APL) interface. In other words, NAPL to APL phase flux is assumed to be equal to the difference between the solubility limit and the "bulk aqueous solution" concentrations times a mass transfer coefficient. Under such assumptions, a few questions are raised: where, in relation to a region of pure NAPL, does the "bulk aqueous solution" regime begin and how does it behave? The answers are assumed to be associated with an arbitrary, predetermined boundary layer, which separates the NAPL from the surrounding solution. The mass transfer rate is considered to be, primarily, limited by diffusion of the component through the boundary layer. In fact, compositional models of interphase mass transfer usually assume that a local equilibrium is reached between phases. Representing mass flux as a rate-limiting process is equivalent to assuming diffusion through a stationary boundary layer with an instantaneous local equilibrium and linear concentration profile. Some environmental researchers have enjoyed success explaining their data using chemical engineering-based correlations. Correlations are strongly dependent on the experimental conditions employed. A universally applicable theory for NAPL dissolution in natural systems does not exist. These correlations are usually expressed in terms of the modified Sherwood number as a function of Reynolds, Peclet, and Schmidt numbers. The Sherwood number may be interpreted as the ratio between the grain size and the thickness of the Nernst stagnant film. In the present study, we show that transfer kinetics at the NAPL/APL interface under equilibrium conditions disagree with approaches based on the Nernst stagnant film concept. It is unclear whether local equilibrium assumptions used in current models are suitable for all situations.A statistical mechanic framework has been chosen to study the transfer kinetic processes at the microscale level. The rationale for our approach is based on both the activation energy of transfer of an ion and its velocity across the NAPL/APL interface. There are four major energies controlling the interfacial NAPL dissolution kinetics: (de)solvation energy, interfacial tension energy, electrostatic energy, and thermal fluctuation energy. Transfer of an ion across the NAPL/APL interface is accelerated by the viscous forces which can be described using the averaged Langevin master equation. The resulting energies and viscous forces were combined using the Boltzmann probability distribution. Asymptotic time limits of the resulting kinetics lead to instantaneous local equilibrium conditions that contradict the Nernst equilibrium equation. The NAPL/APL interface is not an ideal one: it does not conserve energy and heat. In our case the interface is treated as a thin film or slush zone that alters the thermodynamic variables. Such added zone, between the two phases, is itself a phase, and, therefore, the equilibrium does not occur between two phases but rather three. All these findings led us to develop a new non-linearly coupled flow and transport system of equations which is able to account for specific chemical dissolution processes and precludes the need for empirical mass-transfer parameters. Work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract W-7405-Eng-48.

Enhancing national Daily Landslide Hazard Assessments through inter-agency collaboration; lessons learned from storm Desmond (UK)/Synne (Norway), Dec 2015.

NASA Astrophysics Data System (ADS)

Boje, Søren; Devoli, Graziella; Sund, Monica; Freeborough, Katy; Dijkstra, Tom; Reeves, Helen; Banks, Vanessa

2016-04-01

The Norwegian Water Resources and Energy Directorate (NVE) and the British Geological Survey (BGS) compile daily landslide hazard assessments (DLHA) in their respective countries. NVE DLHA has been operational since 2013 and provides national daily assessments based on quantitative thresholds related to daily hydro-meteorological forecasts coupled with qualitative expert analysis of these forecasts. The BGS DLHA has been operational since 2012 and this is predominantly based on expert evaluation of antecedent hydro-meteorological conditions and triggering rainfall across Great Britain (GB). In both cases, the hydro-meteorological evaluation is coupled with observations derived from proprietary datasets on landslide events and landslide potential in order to specify, and limit, the spatial extent of the potentially impacted area. However, the DLHA are strongly driven by hydro-meteorological forecasts. In December 2015, a large extra-tropical cyclone developed over the Atlantic and delivered record-breaking precipitation over parts of the UK and Norway. The meteorological services started naming these events to enhance public uptake and awareness and the storms were named as Desmond (the 4th large storm in 2015/16 in the UK) and Synne (the 5th storm in 2015 in Norway). Desmond arrived in earnest on the 5th of December and brought intense precipitation and strong winds over a 48-hour period. In Cumbria (NW-England) record precipitation was measured (341.4 mm in 24-hour at Honister Pass which is more than twice the monthly average), with 48-hour accumulations exceeding 400 mm. Synne arrived shortly after in Norway and was also characterised by excessive rainfall of 140 mm in 24-hour, 236 mm in 48-hour and 299 mm in 72-hour at Maudal, SW-Norway. Both organisations managed to issue appropriate advance warnings, operating individually. In Norway, warnings were issued some 2 days in advance with a yellow level communicated on Friday 4th and an orange warning the 5th and 6th December. Synne triggered at least 23 landslides, 5 slush flows and 8 snow avalanches. The storm caused also significant floods in the southern sector of the west coast of Norway. In the UK, the DLHA warning level was elevated to yellow on Friday 4th and maintained the following days. Desmond resulted circa 25 landslides that were reported in the media. In both countries, many events were recorded close to transport infrastructure, but the actual number of events is much greater than reported during the storm. The severe consequences of extensive, simultaneous flooding provided a focus for most media reports. Following the events a picture emerged of the wider landscape response through anecdotal photographic evidence and social media. Data gathering therefore continues to date. Even though the issuing of landslide warnings has seen a high rate of success, there are important lessons to be learned regarding the magnitude of landscape response to particular events. This study shows how extreme events can strike several countries at approximately the same time raising landslide forecasting beyond the local environment. Significant gains can be made through inter-agency, international collaboration in order to improve the quality of daily landslide hazard assessments and risk mitigation strategies.

Microbial cell retention in a melting High Arctic snowpack, Svalbard

NASA Astrophysics Data System (ADS)

Zarsky, Jakub; Björkman, Mats; Kühnel, Rafael; Hell, Katherina; Hodson, Andy; Sattler, Birgit; Psenner, Roland

2014-05-01

Introduction The melting snow pack represents a highly dynamic system not only for chemical compounds but also for bacterial cells. Microbial activity was found at subzero temperatures in ice veins when liquid water persists due to high concentration of ions on the surface of snow crystals and brine channels between large ice crystals in ice. Several observations also suggest microbial activity under subzero temperatures in seasonal snow. Even with regard to the spatial and temporal relevance of snow ecosystems, microbial activity in such an extreme habitat represents a relatively small proportion in the carbon flux of the global ecosystem and even of the glacial ecosystems specifically. On the other hand, it represents a remarkable piece of mosaic of the microbial activity in glacial ecosystems because the snow pack represents the first contact between the atmosphere and cryosphere. This topic also embodies vital crossovers to biogeochemistry and ecotoxicology, offering a quantitative view of utilization of various substrates relevant for downstream ecosystems. Here we present our study of the dynamics of both solvents and cells suspended in meltwater of the melting snowpack on a high arctic glacier to demonstrate the spatio-temporal constraint of interaction between solvent and bacterial cells in this environment. Method We used 6 lysimeters inserted into the bottom of the snowpack to collect replicated samples of melt water before it comes into contact with basal ice or slush layer at the base of the snow pack. The sampling site was chosen at Midre Lovénbreen (Svalbard, Kongsfjorden, MLB stake 6) where the snow pack showed melting on the surface but the basal ice was still dry. Sampling was conducted in June 2010 for a period of 10 days once per day and the snow profile was sampled according to distinguished layers in the profile at the beginning of the field mission and as bulk at its end. The height of snow above the lysimeters dropped from the initial 74 cm to the final 38 cm. The major ion composition (IC), pH, conductivity and cell abundances were measured. Results and conlusions The removal of microbial cells from a high arctic snowpack resembles an elution sequence similar to that of hydrophobic compounds a process that helps glaciers retain a microbial biomass upon their surface, even after the demise of the snow cover. The snowpack and the glacier surface therefore act as an accumulator of cells during the melt season. This suggests that wet snowpacks, even on the surface of high arctic glaciers, are likely to be dynamic ecosystems in their own right. In our study, a clear ion elution sequence was observed that resembled earlier reports and caused high concentrations of ions in snowpack runoff at the start of the snow melt, which rapidly decreased as snow melt proceeded. Chloride, sulfate, nitrate, sodium and potassium experienced a 50 % elution before 20 - 25 % of the snowpack water content was lost. By contrast, cell removal only reached the 50 % level after ~70 % snowpack depletion. In contrast to our expectations, the calculated cell budget between the initial and final snowpack (including the cell loss by elution), revealed a significant increase of the total cell numbers, i.e. more than twice the original number. Assuming aeolian deposition processes to be low, this suggests cell proliferation as a contribution to the observed "retention effect". Precipitation was the major cell contributor to the snowpack upon Midtre Lovénbreen. An overall low cell concentration was therefore found within the snowpack stratigraphy, where snow layers frequently showed cell abundances similar to those of cloud water. This was in contrast to the nearby and more wind exposed sites examined in the Kongsfjorden area in 2007. However, layers of higher dust deposition were concomitant with one order of magnitude higher cell abundances, indicating that wind dispersal from locally exposed rocks supplements the atmospheric cell input.

Geomorphic influences of the Little Ice Age glacial advance on selected hillslope systems in Nordfjord, Western Norway (Erdalen and Bødalen valleys)

NASA Astrophysics Data System (ADS)

Laute, Katja; Beylich, Achim A.

2010-05-01

Hillslopes in glacially formed landscapes are typically characterized by talus cones developed beneath free rock faces. Studying hillslopes as sedimentary source, storage and transfer zones as well as surface processes acting on hillslopes since the end of the deglaciation is of importance in order to gain a better understanding of the complex sedimentary source-to-sink fluxes in cold climate environments. Hillslopes function as a key component within the geomorphic process response system. Large areas of the Norwegian fjord landscapes are covered by hillslopes and are characterized by the influences of the glacial inheritance. This PhD project is part of the NFR funded SedyMONT-Norway project within the ESF TOPO-EUROPE SedyMONT (Timescales of sediment dynamics, climate and topographic change in mountain landscapes) programme. The focus of this study is on geomorphic influences of the Little Ice Age glacial advance on postglacial hillslope systems in four distinct headwater areas of the Erdalen and Bødalen valleys in the Nordfjord valley-fjord system (inner Nordfjord, Western Norway). Both valleys can be described as steep, U-shaped and glacier-fed, subarctic tributary valleys. Approximately 14% of the 49 km2 large headwater areas of Erdalen are occupied by hillslope deposits and 41% by rock surfaces; in Bødalen hillslope deposits occupy 12% and rock surfaces occupy 38% of the 42 km2 large headwater areas. The main aims of this study are (i) to analyze and compare the morphometric characteristics as well as the composition of hillslope systems inside and outside of the Little Ice Age glacial limit, (ii) to detect possible changes within the mass balances of these hillslope systems, (iii) to identify the type and intensity of currently acting hillslope processes as well as (iv) to determine possible sediment sources and delivery pathways within the headwater areas of the catchments. The process-based approach includes orthophoto- and topographical map interpretation, hillslope profile surveying, photo monitoring, geomorphological mapping as well as GIS and DEM computing. Two appropriate hillslope test sites within each headwater area are selected in order to follow the main aims of this study. The designed monitoring instrumentation of the slope test sites includes nets for collecting freshly accumulated rockfall debris, stone tracer lines for measuring surface movements, wooden sticks for monitoring of slow surface creep movements and peg lines for depth-integrated measurements of slow mass movements. In addition, remote site cameras for monitoring rapid mass movement events (avalanches, slush- and debris flows) and slope wash traps for analyzing slope wash denudation are installed and measurements of solute concentrations at small hillslope drainage creeks for investigating the role of chemical denudation are conducted. Measurements of morphometric characteristics and longitudinal profiles along the main axis of the talus cones are carried out at each test site. The manually obtained longitudinal profile data are combined with data derived from a DEM in order to generate complete longitudinal hillslope profiles reaching from the apex until the slope foot. Preliminary results show a steepening trend of the talus cones located inside the Little Ice Age glacier limit which is due to erosion during the Little Ice Age glacial advance. In addition, some of these talus cones are characterized by a recognizable more complex talus cone morphometry and composition, resulting from implementation of Little Ice Age glacier side moraines. The combination of (i) steepened talus cones and (ii) complex composition seems to increase currently acting hillslope processes which leads to a higher sediment delivery from these slopes as compared to hillslopes outside the Little Ice Age glacier limit. The implementation of moraine material but also the increased intensity of denudative processes has a recognizable influence on the mass balance of the hillslope systems inside the Little Ice Age glacier limit. Research on the complex development of hillslope systems from a postglacial to contemporary time perspective in combination with analyses of contemporary sedimentary fluxes contributes to a better understanding of hillslopes acting as source, storage and transfer zones in cold climate environments (paraglacial systems).