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1

1D Transient Model for Frost Heave in PEFCs III. Heat Transfer, Microporous Layer, and Cycling Effects  

E-print Network

1D Transient Model for Frost Heave in PEFCs III. Heat Transfer, Microporous Layer, and Cycling 446-912, Korea A computational model based on a frost heave mechanism has been developed to simulate-5,11-16 To determine the root cause of freeze/thaw dam- age, a frost heave thermal model has been developed

Mench, Matthew M.

2

Frost-free North Polar Layers in the Good Old Summertime  

NASA Technical Reports Server (NTRS)

17 October 2006 The middle portion of the northern summer season is the ideal time of year to capture relatively dust- and haze-free views of martian north polar terrain. This year, much more of the north polar cap has sublimed away than has been evident in previous northern summers going back to 1999, when Mars Global Surveyor (MGS) began the Mapping Phase of the mission. This MGS Mars Orbiter Camera (MOC) image shows a nearly ice-free view of layers exposed by erosion in the north polar region. The light-toned patches are remnants of water ice frost. The layers are generally considered by the Mars scientific community to be record of past depositions of ice and dust. This picture is located near 82.5oN, 118.6oW, and covers an area about 3 km by 10 km (1.9 by 6.2 miles). Sunlight illuminates the scene from the upper left; the image was acquired on 22 September 2006.

2006-01-01

3

Enhanced by Frost  

NASA Technical Reports Server (NTRS)

30 September 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows outcrops of south polar layered terrain. Their appearance in this July 2005 springtime image is enhanced by bright patches of carbon dioxide frost. The frost is left over from the previous southern winter season; by summer, the frost would be gone.

Location near: 84.6oS, 203.5oW Image width: width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Spring

2005-01-01

4

Frosted Dunes  

NASA Technical Reports Server (NTRS)

17 June 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a group of sand dunes, covered by seasonal carbon dioxide frost, in the martian north polar region. Over the course of northern hemisphere spring, the carbon dioxide frost sublimes away, slowly revealing the dark sand that makes up the dunes. The dark spots in this image may be patches of freshly-exposed sand, or they could be places where the CO2 frost has changed, either becoming rougher, coarser-grained (larger crystals), or both. A rougher or coarser-grained surface will appear darker because of an increase in shadowing of the surface by the small-scale roughness elements.

Location near: 75.2oN, 51.3oW Image width: 3 km (1.9 mi) Illumination from: lower left Season: Northern Spring

2006-01-01

5

Identifying and Mapping Seasonal Surface Water Frost with MGS TES  

NASA Astrophysics Data System (ADS)

The Thermal Emission Spectrometer (TES) visible/near-infrared and thermal infrared bolometers measured surface broadband albedo and temperature for more than three Mars years. As seasons progress on Mars, surface temperatures may fall below the frost point of volatiles in the atmosphere (namely, carbon dioxide and water). Systematic mapping of the spatial and temporal occurrence of these volatiles in the martian atmosphere, on the surface, and in the subsurface has shown their importance in understanding the climate of Mars. However, few studies have investigated seasonal surface water frost and its role in the global water cycle. We examine zonally-averaged TES daytime albedo, temperature, and water vapor abundance data [after Smith, 2004] to map the presence of surface water frost on Mars. Surface water frost occurs in the polar and mid latitudes, in regions with surface temperatures less than 220 K and above 150 K, and can significantly increase albedo relative to the bare surface. In the northern hemisphere water frost is most apparent in late fall/early winter, before the onset of carbon dioxide frost. Dust storms occurring near northern winter solstice affect albedo data and prevent us from putting a latitudinal lower limit on the water frost in the northern hemisphere. Regardless, seasonal water frost occurs at least as low as 48°N in Utopia Planitia, beginning at Ls=~230°, as observed by Viking Lander 2 [Svitek and Murray, 1990]. Daytime surface water frost was also observed at the Phoenix Lander site (68°N) beginning at Ls=~160° [Cull et al., 2010]. The timing of albedo variations observed by TES agree relatively well with lander observations of seasonal frost. Seasonal water frost is not detected during fall in the southern hemisphere. A potential explanation for this discrepancy, compared with frost detections in the north, is the disparity in atmospheric water vapor abundance between the two hemispheres. The frost point temperatures for water vapor in the southern hemisphere are ~5-10 K lower for the corresponding season and latitude in the north [Smith, 2004]. This inhibits the stability of water frost on the surface in the southern hemisphere and also lowers the maximum thickness of a water frost layer, potentially limiting its effect on surface albedo. Our work here shows that the seasonal progression in the northern hemisphere of Mars involves extensive deposition of water frost, similar in progression to the carbon dioxide seasonal ice cap. This behavior results in variation of surface albedo and therefore affects surface and subsurface temperatures, which could impact the distribution of ground ice. Surface frost and subsequent mixing of vapor back into the atmosphere likely plays an important role in the global water cycle. Mapping of water frost's geographical extent, timing, and impact on surface albedo can provide insight into the processes controlling the present Martian climate. References: Cull, S. et al. (2010) JGR, 115, E00E19. Smith, M. D. (2004) Icarus, 167, 148-165. Svitek, T. and Murray, B. (1990) JGR, 95(B2), 1495-1510.

Bapst, J.; Bandfield, J. L.; Wood, S. E.

2013-12-01

6

Robert Frost on Writing.  

ERIC Educational Resources Information Center

This book is a collection of Frost's letters, reviews, introductions, lectures, and interviews on writing dating back to 1913. It provides Frost's view of literature, and its relation to language and social order. Part one, "Frost as a Literary Critic," discusses the scope of Frost's criticism and Frost as both critical theorist and practical…

Barry, Elaine

7

Polygons in Martian Frost  

NASA Technical Reports Server (NTRS)

MGS MOC Release No. MOC2-428, 21 July 2003

This June 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a polygonal pattern developed in seasonal carbon dioxide frost in the martian southern hemisphere. The frost accumulated during the recent southern winter; it is now spring, and the carbon dioxide frost is subliming away. This image is located near 80.4oS, 200.2oW; it is illuminated by sunlight from the upper left, and covers an area 3 km (1.9 mi) across.

2003-01-01

8

Frost tolerance of Trifolium species  

Microsoft Academic Search

Thirteen Trifolium species were artificially frosted at ?4, ?8, ?12, and ?16°C in controlled environment rooms. This was carried out in such a way that soil freezing was avoided and only shoots were frosted. Frost tolerance was primarily assessed as the percentage of dead to total leaf dry weight present 1 week after frosting. Trifolium arvense, T. dubium, and T.

J. R. Caradus

1995-01-01

9

Frost Formation and Defrosting for Heat Pump Systems  

NASA Astrophysics Data System (ADS)

Recently, frost formation becomes an more important phenomenon not only in the cryogenic equipment but also in the air conditioner equipped with heat pump systems. When heat pump systems are used to supply thermal energy from air for the purpose of space heating in winter, the surface temperature of the evaporator often falls below 0°C and then frost deposition occurs there because it gains heat from the cold outdoor air. Frost formation cannot be treated easily as a growth of uniform substances such as ice because of the complicated nature of a frost layer. Accordingly, frost formation has been studied from the various points of view. This paper will give a review of studies on frost fomation and defrosting connected with heat pump systems.

Aoki, Kazuo

10

A model for nocturnal frost formation on a wing section: Aircraft takeoff performance penalties  

NASA Technical Reports Server (NTRS)

The nocturnal frost formation on a wing section, to explain the hazard associated with frost during takeoff was investigated. A model of nocturnal frost formation on a wing section which predicts when the nocturnal frost will form and also its thickness and density as a function of time was developed. The aerodynamic penalities as related to the nocturnal frost formation properties were analyzed to determine how much the takeoff performance would be degraded by a specific frost layer. With an aircraft takeoff assuming equations representing a steady climbing flight, it is determined that a reduction in the maximum gross weight or a partial frost clearance and a reduction in the takeoff angle of attack is needed to neutralize drag and life penalities which are due to frost. Atmospheric conditions which produce the most hazardous frost buildup are determined.

Dietenberger, M. A.

1983-01-01

11

Frosted Sand Dunes  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site] (Released 22 July 2002) This image, located near 79.6 N and 142.7 E, displays sand dunes covered in CO2 frost. This is a region of Mars that contains circumpolar sand seas. The large sand deposits and the high winds that circulate around the pole allow for the formation of a huge dune field that surrounds the north polar cap. As the northern hemisphere progresses towards winter, CO2 frost condenses out of the atmosphere and covers the dunes. During northern spring, the CO2 sublimates and the dunes are once again uncovered and active. This image was taken as northern spring progresses and the crests of the dunes are just starting to be exposed. The dark dune material absorbs sunlight more efficiently than the brighter frost, aiding in the sublimation of the remaining frost.

2002-01-01

12

Dynamic Measurements of Laser Light Attenuation by Cryogen Film and Frost Formation  

E-print Network

Dynamic Measurements of Laser Light Attenuation by Cryogen Film and Frost Formation Bernard Choi1 surface. The cryogen pool eventually evaporates as frost forms on the skin surface due to condensation. The purpose of this study was to investigate laser light attenuation by the cryogen film/frost layer. Medical

Aguilar, Guillermo

13

Transient Heat Transfer Around a Horizontal Cylinder while Frosting  

NASA Astrophysics Data System (ADS)

This study examined transient heat transfer characteristics while frosting in order to clarify heat transfer mechanism by which a high heat flux is obtained at the frosting initial stage. For the purpose, a high-precise temperature measurement was carried out in the frost layer and outside of a horizontal cylinder. The thermocouples for the temperature measurement were composed of a chromel wire of 0.1 diameter and several constantan wires of 0.05mm diameter. The chromel wire was welded on the surface of the horizontal cylinder, and several constantan wires were welded in about a 1mm interval on the surface of the chromel wire. As a result, the surface temperature of the frost layer proportionally increased with the increase in the thickness of the frost layer. The time mean value of the measured local Nusselt number decreased in order of the value in the upper part of the cylinder, intermediate and lower parts, were respectively 11.5, 7.5 and 6.0. The measured thermal conductivity of the frost layer rose with the increase in the thickness of the frost layer, and the value was within 0.04-0.12 W/mK.

Nakagawasai, Manabu; Kawashima, Hisanobu; Maehara, Yoshiyuki; Kumakura, Hiroshi; Inada, Shigeaki

14

Moisture performance analysis of EPS frost insulation  

SciTech Connect

A horizontal layer of expanded polystyrene foam (EPS) is widely used as a frost insulation of building foundations in the Nordic countries. The performance properties of the insulation depend strongly on the moisture level of the material. Experimental methods are needed to produce samples for testing the material properties in realistic moisture conditions. The objective was to analyze the moisture loads and the wetting mechanisms of horizontal EPS frost insulation. Typical wetting tests, water immersion and diffusive water vapor absorption tests, were studied and the results were compared with the data from site investigations. Usually these tests give higher moisture contents of EPS than what are detected in drained frost insulation applications. Also the effect of different parameters, like the immersion depth and temperature gradient were studied. Special attention was paid to study the effect of diffusion on the wetting process. Numerical simulation showed that under real working conditions the long period diffusive moisture absorption in EPS frost insulation remained lower than 1% Vol. Moisture performance was determined experimentally as a function of the distance between the insulation and the free water level in the ground. The main moisture loads and the principles for good moisture performance of frost insulation are presented.

Ojanen, T.; Kokko, E.

1997-11-01

15

Frost on Mars  

NASA Technical Reports Server (NTRS)

This image shows bluish-white frost seen on the Martian surface near NASA's Phoenix Mars Lander. The image was taken by the lander's Surface Stereo Imager on the 131st Martian day, or sol, of the mission (Oct. 7, 2008). Frost is expected to continue to appear in images as fall, then winter approach Mars' northern plains.

The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

2008-01-01

16

A frost formation model and its validation under various experimental conditions  

NASA Technical Reports Server (NTRS)

A numerical model that was used to calculate the frost properties for all regimes of frost growth is described. In the first regime of frost growth, the initial frost density and thickness was modeled from the theories of crystal growth. The 'frost point' temperature was modeled as a linear interpolation between the dew point temperature and the fog point temperature, based upon the nucleating capability of the particular condensing surfaces. For a second regime of frost growth, the diffusion model was adopted with the following enhancements: the generalized correlation of the water frost thermal conductivity was applied to practically all water frost layers being careful to ensure that the calculated heat and mass transfer coefficients agreed with experimental measurements of the same coefficients.

Dietenberger, M. A.

1982-01-01

17

A transient analysis of frost formation on a parallel plate evaporator  

SciTech Connect

This paper presents the development of a transient model for evaluating frost formation on a parallel plate evaporator for heat pump applications. The model treats the frost layer as a porous substance, and applies the equations of conservation of mass, momentum and energy to calculate the growth and densification of the frost layer. Empirical correlations for thermal conductivity and tortuosity as a function of density are incorporated from previous studies. Frost growth is calculated as a function of time, Reynolds number, longitudinal location, plate temperature, and ambient air temperature and humidity. The main assumptions are: ideal gas behavior for air and water vapor, uniform frost density and thermal conductivity across the thickness of the frost layer; and quasi-steady conditions during the whole process. The mathematical model is validated by comparing the predicted values of frost thickness and frost density with results obtained in recent experimental studies. A good agreement was obtained in the comparison. The frost formation model calculates pressure drop and heat transfer resistance that result from the existence of the frost layer, and it can therefore be incorporated into a heat pump model to evaluate performance losses due to frosting as a function of weather conditions and time of operation since the last evaporator defrost.

Martinez-Frias, J.; Aceves, S.M.; Hernandez-Guerrero, A. [Univ. of Guanajuato (Mexico). Dept. of Mechanical Engineering

1996-12-31

18

Frost heave Alan W. REMPEL  

E-print Network

Frost heave Alan W. REMPEL Department of Geological Science, University of Oregon, Eugene, Oregon that is produced by frost heave has motivated almost a century of concerted laboratory, field and theoretical predictive models for the macroscopic frost-heave characteristics that are seen in the field

Rempel, Alan W.

19

Frost-covered dunes  

NASA Technical Reports Server (NTRS)

MOC image of dunes in Chasma Boreale, a giant trough in the north polar cap. This September 1998 view shows dark sand emergent from beneath a veneer of bright frost left over from the northern winter that ended in July 1998.

1999-01-01

20

Tints, Shades and Frost  

ERIC Educational Resources Information Center

This article describes a classroom art project inspired by the work of Robert Frost, one of the most acclaimed and beloved American poets of all time. Using tints and shades in a composition, this project demonstrates how quality literature may be incorporated into elementary art lessons in a very useful way, making art an important complement to…

Sterling, Joan

2009-01-01

21

Morning Frost on Martian Surface  

NASA Technical Reports Server (NTRS)

A thin layer of water frost is visible on the ground around NASA's Phoenix Mars Lander in this image taken by the Surface Stereo Imager at 6 a.m. on Sol 79 (August 14, 2008), the 79th Martian day after landing. The frost begins to disappear shortly after 6 a.m. as the sun rises on the Phoenix landing site.

The sun was about 22 degrees above the horizon when the image was taken, enhancing the detail of the polygons, troughs and rocks around the landing site.

This view is looking east southeast with the lander's eastern solar panel visible in the bottom lefthand corner of the image. The rock in the foreground is informally named 'Quadlings' and the rock near center is informally called 'Winkies.'

This false color image has been enhanced to show color variations.

The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

2008-01-01

22

OZONE: Layer Identification in the presence of Cyclic Dependencies Jannik Lavala  

E-print Network

OZONE: Layer Identification in the presence of Cyclic Dependencies Jannik Lavala , Nicolas://rmod.lille.inria.fr Abstract A layered software architecture helps understanding the role of software entities (e.g., packages of an optimal layered organization in the presence of cyclic dependencies is difficult. In this paper, we

Paris-Sud XI, Université de

23

Frost in Charitum Montes  

NASA Technical Reports Server (NTRS)

MGS MOC Release No. MOC2-387, 10 June 2003

This is a Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) wide angle view of the Charitum Montes, south of Argyre Planitia, in early June 2003. The seasonal south polar frost cap, composed of carbon dioxide, has been retreating southward through this area since spring began a month ago. The bright features toward the bottom of this picture are surfaces covered by frost. The picture is located near 57oS, 43oW. North is at the top, south is at the bottom. Sunlight illuminates the scene from the upper left. The area shown is about 217 km (135 miles) wide.

2003-01-01

24

Polygons in Seasonal Frost  

NASA Technical Reports Server (NTRS)

8 February 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a summertime scene in the south polar region of the red planet. A patch of bright frost--possibly water ice--is seen in the lower third of the image. Polygon patterns that have developed in the ice as it sublimes away can be seen; these are not evident in the defrosted surfaces, so they are thought to have formed in the frost. This image is located near 82.6oS, 352.5oW. Sunlight illuminates this scene from the upper left; the image covers an area 3 km (1.9 mi) wide.

2004-01-01

25

Frost on Dunes  

NASA Technical Reports Server (NTRS)

18 March 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows dark dunes on a crater floor during the southern spring. Some of the dunes have frost on their south-facing slopes.

Location near: 52.3oS, 326.7oW Image width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Spring

2005-01-01

26

Water frost on Charon  

NASA Technical Reports Server (NTRS)

New spectra of the Pluto-Charon system taken just before and during a total eclipse of the satellite are presented. The spectrum of Charon extracted from the data reveals the signature of water ice. There is no evidence for any methane or ammonia frost on the surface of Charon. The significance of these findings for the evolution of the Pluto-Charon system are discussed.

Buie, Marc W.; Cruikshank, Dale P.; Lebofsky, Larry A.; Tedesco, Edward F.

1987-01-01

27

Frost Forecasting for Fruitgrowers  

NASA Technical Reports Server (NTRS)

Progress in forecasting from satellite data reviewed. University study found data from satellites displayed in color and used to predict frost are valuable aid to agriculture. Study evaluated scheme to use Earth-temperature data from Geostationary Operational Environmental Satellite in computer model that determines when and where freezing temperatures endanger developing fruit crops, such as apples, peaches and cherries in spring and citrus crops in winter.

Martsolf, J. D.; Chen, E.

1983-01-01

28

Polar frost formation on Ganymede  

NASA Technical Reports Server (NTRS)

Voyager photographs have shown the presence of polar frost on Ganymede, a satellite of Jupiter. A number of models have been proposed for the formation of this feature. The models are based on the transport of material from the equatorial to the polar regions. The present paper is concerned with a model regarding the origin and appearance of the Ganymede caps which does not depend on such a transport. The model is based on observations of the surficial changes produced by ion bombardment. It is pointed out that experiments on ion and electron bombardment of water ice at low temperatures have shown that these particles sputter significant quantities of water molecules. In addition, they also change the visual characteristics of the surface significantly. Ion bombardment competing with thermal reprocessing may be sufficient to explain the latitudinal differences observed on Ganymede.

Johnson, R. E.

1985-01-01

29

Influences of surface hydrophilicity on frost formation on a vertical cold plate under natural convection conditions  

SciTech Connect

Surface hydrophilicity has a strong influence on frost nucleation according to phase transition theory. To study this effect, a close observation of frost formation and deposition processes on a vertical plate was made under free convection conditions. The formation and shape variation of frost crystals during the initial period are described and the frost thickness variation with time on both hydrophobic and plain copper cold surfaces are presented. The various influencing factors are discussed in depth. The mechanism of surface hydrophilicity influence on frost formation was analyzed theoretically. This revealed that increasing the contact angle can increase the potential barrier and restrain crystal nucleation and growth and thus frost deposition. The experimental results show that the initial water drops formed on a hydrophobic surface are smaller and remain in the liquid state for a longer time compared with ones formed on a plain copper surface. It is also observed that the frost layer deposited on a hydrophobic surface is loose and weak. Though the hydrophobic surface can retard frost formation to a certain extent and causes a looser frost layer, our experimental results show that it does not depress the growth of the frost layer. (author)

Liu, Zhongliang; Zhang, Xinghua; Wang, Hongyan; Meng, Sheng; Cheng, Shuiyuan [Key Laboratory of Enhanced Heat Transfer and Energy Conservation, Ministry of Education and Key Laboratory of Heat Transfer and Energy Conversion, Beijing Education Commission, College of Environmental and Energy Engineering, Beijing University of Technology, Pingleyuan 100, Beijing 100022 (China)

2007-07-15

30

Jack's Frost: Controllable Magic Frost Simulations for 'Rise of the Guardians' David Lipton*  

E-print Network

Jack's Frost: Controllable Magic Frost Simulations for 'Rise of the Guardians' David Lipton* Ken Jack Frost has the ability to cover objects in swirling, magical frost. The frost is an extension. To achieve this, we built a Houdini based system that allowed for precise control over the frost's animation

31

Seasonal Frost Changes on Mars  

NASA Technical Reports Server (NTRS)

Observations by NASA's 2001 Mars Odyssey spacecraft show a comparison of wintertime (left) and summertime (right) views of the north polar region of Mars in intermediate-energy, or epithermal, neutrons. The maps are based on data from the high-energy neutron detector, an instrument in Odyssey's gamma-ray spectrometer suite. Soil enriched by hydrogen is indicated by the purple and deep blue colors on the maps. Progressively smaller amounts of hydrogen are shown in the colors light blue, green, yellow and red. The hydrogen is believed to be in the form of water ice. In some areas, the abundance of water ice is estimated to be up to 90% by volume. In winter, much of the hydrogen is hidden beneath a layer of carbon dioxide frost (dry ice). In the summer, the hydrogen is revealed because the carbon dioxide frost has dissipated. A shaded-relief rendition of topography is superimposed on these maps for geographic reference.

NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. Investigators at Arizona State University in Tempe, the University of Arizona in Tucson, and NASA's Johnson Space Center, Houston, operate the science instruments. The gamma-ray spectrometer was provided by the University of Arizona in collaboration with the Russian Aviation and Space Agency and Institute for Space Research (IKI), which provided the high-energy neutron detector, and the Los Alamos National Laboratories, New Mexico, which provided the neutron spectrometer. Lockheed Martin Astronautics, Denver, is the prime contractor for the project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

2003-01-01

32

Differential frost heave model for patterned ground formation: Corroboration with observations along a North American arctic transect  

Microsoft Academic Search

Frost boils in the Arctic are a manifestation of patterned ground in the form of nonsorted circles. Active frost boils involve convection of water through the soil that can bring basic salts from depth to the surface. As such, active frost boils can mitigate acidification and thereby strongly influence the type of vegetation supported by Arctic soils. The presence or

R. A. Peterson; W. B. Krantz

2008-01-01

33

Winter Frost and Fog  

NASA Technical Reports Server (NTRS)

This somewhat oblique blue wide angle Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows the 174 km (108 mi) diameter crater, Terby, and its vicinity in December 2004. Located north of Hellas, this region can be covered with seasonal frost and ground-hugging fog, even in the afternoon, despite being north of 30oS. The subtle, wavy pattern is a manifestation of fog.

Location near: 28oS, 286oW Illumination from: upper left Season: Southern Winter

2005-01-01

34

Sand Dunes with Frost  

NASA Technical Reports Server (NTRS)

9 May 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a suite of frost-covered sand dunes in the north polar region of Mars in early spring, 2004. The dunes indicate wind transport of sand from left to right (west to east). These landforms are located near 78.1oN, 220.8oW. This picture is illuminated by sunlight from the lower left and covers an area about 3 km (1.9 mi) across.

2004-01-01

35

Seeing through Frost on Enceladus  

NASA Astrophysics Data System (ADS)

It is now well-established that active cryovolcanism on Enceladus populates the E-ring with icy dust grains, that re-accreting E-ring particles bombard and globally modify the surfaces of Enceladus and its satellite neighbors (cf. Verbiscer et al. 2007, Science 315, pp. 815; Kempf et al. 2010, Icarus 206, 446-457), and that direct fallout from eruptive plumes creates distinct, predicable broad-scale regional patterns of albedo and color on the surface of Enceladus (Schenk et al. 2010, Icarus 211, 740-757). However, at present it is not clearly established how thickly that plume fallout mantles the surface from location to location, how the presence of plume fallout affects the appearance and detection of underlying geological features, how rapidly the deposits accumulate, how long they have been accumulating, or how plume fallout, E-ring bombardment, and endogenic processes like thermal annealing and seismic shaking, for example near active tiger stripe rifts, compete and combine to modify the shape of geological structures at size-scales of kilometers or less that are much smaller than those that are represented in the regional albedo patterns found by Schenk et al. (2010). Early Cassini Narrow Angle Camera (NAC) images of Enceladus' Western Hemisphere (leading-side) that were obtained at relatively large phase angles (?>90°) and spatial resolutions better than about 1 km/pixel clearly identify peculiar circular albedo structures with diameters of tens of kilometers. One feature (here called P1) at 9.1°S, 83.0°W is conspicuously darker than its surroundings, while an adjacent feature (P2) at 24.1°S, 73.5°W is comparable in brightness to its surroundings except for a relatively bright diffuse patch that appears to be ejecta from a superposed small impact crater. The subdued circular surface relief of these features and overprinting by quasi-linear tectonic features suggest that they may be palimpsest-like structures or else surface expressions of diapirism (cf. Spencer et al. 2009, In "Saturn after Cassini-Huygens", Springer-Verlag. 683-724; Helfenstein et al. 2010; American Geophysical Union, Fall Meeting 2010, abstract #P23C-04). More recent Cassini high-resolution imaging of the region over a wide range of illumination geometry reveals a systematic change in the appearance of the circular albedo features as the phase angle decreases from ?=124° to ?=31° -- the circular albedo features that are so clearly visible at large phase angles are completely masked at small phase angles. The decrease in the albedo contrast with decreasing phase angle is dramatic: The average albedo contrast between the circular P1 and P2 features diminishes from 27±3% at phase ?=124° to only 1.3±0.2% at ?=31°. A likely explanation for this photometric behavior is that it reveals a top layer of frost or snow that scatters light strongly at relatively small phase angles, but which becomes more transparent as phase angles increase allowing Cassini to see through to underlying features. It is also possible that the changing photometric contrasts arise from terrain-dependent differences in regolith properties like surface roughness or regolith grain-size.

Helfenstein, P.

2012-12-01

36

Frost characteristics and heat transfer on a flat plate under freezer operating conditions: Part 2, Numerical modeling and comparison with data  

SciTech Connect

An existing numerical model for frost growth as a porous media is modified to include boundary conditions for a relatively high-density frost layer adjacent to a cold plate and turbulent airflow over a rough frost-air interface. Low-density frost grows on top of this high-density surface layer. Simulation results compare well with the data for selected test conditions where experimental uncertainty is small. When the experimental uncertainty is small, a validated physical/numerical model may be the best means of interpreting the physical nature of frost growth and extrapolating a limited database for frost growth.

Chen, H.; Besant, R.W.; Tao, Y.X.

1999-07-01

37

Frost-free Dunes  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site] Context image for PIA03291 Frost-free Dunes

These dark dunes are frost covered for most of the year. As southern summer draws to a close, the dunes have been completely defrosted.

Image information: VIS instrument. Latitude -66.6N, Longitude 37.0E. 34 meter/pixel resolution.

Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

2006-01-01

38

Dunes with Frost  

NASA Technical Reports Server (NTRS)

31 May 2004 Springtime for the martian northern hemisphere brings defrosting spots and patterns to the north polar dune fields. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an example located near 76.7oN, 250.4oW. In summer, these dunes would be darker than their surroundings. However, while they are still covered by frost, they are not any darker than the substrate across which the sand is slowly traveling. Dune movement in this case is dominated by winds that blow from the southwest (lower left) toward the northeast (upper right). The picure covers an area about 3 km (1.9 mi) across and is illuminated by sunlight from the lower left.

2004-01-01

39

Seasonal Frost in Terra Sirenum  

NASA Technical Reports Server (NTRS)

This image of the Terra Sirenum region of Mars was taken by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) at 0918 UTC (4:18 a.m. EST) on Nov. 25, 2006, near 38.9 degrees south latitude, 195.9 degrees east longitude. CRISM's image was taken in 544 colors covering 0.36-3.92 micrometers, and shows features as small as 18 meters (60 feet) across.

At this time, Mars' southern hemisphere was experiencing mid-winter. During Martian southern winter, the southern polar cap is covered and surrounded by carbon dioxide frost and water frost. This is unlike Earth, whose frozen winter precipitation is made up of only one volatile -- water. The carbon dioxide frost evaporates, or sublimates, at a lower temperature than water frost. So, during spring, the carbon dioxide ice evaporates first and leaves a residue of water frost, which later sublimates as well.

The image shown here covers part of a crater rim, which is illuminated from the upper left. North is at the top. The topography creates a cold microenvironment on the south side of the rim that is partially protected from solar illumination. That cold surface contains an outlier of the southern seasonal frost about 15 degrees of latitude closer to the equator than the average edge of the frost at this season.

The top image was constructed from three infrared wavelengths that highlight the bluer color of frost than the background rock and soil. Note that the frost occurs both on sunlit and shaded surfaces on the south side of the rim. The shaded areas are still visible because they are illuminated indirectly by the Martian sky.

The bottom image was constructed by measuring the depths of spectral absorption bands due to water frost and carbon dioxide frost, and displaying the results in image form. Blue shows strength of an absorption due to water frost near 1.50 micrometers, and green shows strength of an absorption due to carbon dioxide frost near 1.45 micrometers. Red shows brightness of the surface at 1.33 micrometers -- outside of the frost absorption bands -- in order to show the relationship of frost to the illuminated crater rim.

In comparing the top and bottom images, note that water frost occurs in many locations on the south-facing side of the crater rim, both in sunlit and shaded areas. Because it faces away from the sun, this side of the crater rim is colder than the north, sun-facing side. This favors the formation of frost. In contrast, carbon dioxide frost occurs only in the coldest, most shaded areas.

CRISM's mission: Find the spectral fingerprints of aqueous and hydrothermal deposits and map the geology, composition and stratigraphy of surface features. The instrument will also watch the seasonal variations in Martian dust and ice aerosols, and water content in surface materials -- leading to new understanding of the climate.

The Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) is one of six science instruments on NASA's Mars Reconnaissance Orbiter. Led by The Johns Hopkins University Applied Physics Laboratory, the CRISM team includes expertise from universities, government agencies and small businesses in the United States and abroad.

2006-01-01

40

Robert Frost: Teacher "Earner, Learner, Yearner."  

ERIC Educational Resources Information Center

An account of Robert Frost's teaching, along with an assessment of it, are presented. Material consulted includes Frost's published letters, prose, and poetry; Lawrance Thompson's authorized biography; Lesley Frost's "New Hampshire's Child: The Derry Journals of Lesley Frost;" and additional sources such as films and periodicals, particularly…

Vogel, Nancy Sue

41

Pluto - Evidence for methane frost  

NASA Technical Reports Server (NTRS)

Results are presented for infrared photometry of Pluto in the wavelength range from 1.2 to 2.2 microns, which includes the diagnostic absorption bands of water and methane frosts (designated as H1 and H2, respectively). Based on Pluto's observed J-H color and H1/H2 reflectance ratio as well as restrictions imposed by other observational and theoretical studies, it is concluded that methane frost is probably the dominant reflecting material on the planet's surface. It is suggested that this frost may be mixed with other materials, and some variation of the frost cover is indicated. Two plausible sources for the methane on Pluto are discussed, the average geometric albedo of the planet is assumed to be 0.4, and its diameter is estimated to be 3300 km.

Cruikshank, D. P.; Pilcher, C. B.; Morrison, D.

1976-01-01

42

Free magnetohydrodynamic shear layers in the presence of rotation and magnetic field  

SciTech Connect

We present an experimental and numerical study of hydrodynamic and magnetohydrodynamic free shear layers and their stability. We first examine the experimental measurement of globally unstable hydrodynamic shear layers in the presence of rotation and their range of instability. These are compared to numerical simulations, which are used to explain the modification of the shear layer, and thus the critical Rossby number for stability. Magnetic fields are then applied to these scenarios and globally unstable magnetohydrodynamic shear layers generated. These too are compared to numerical simulations showing behavior consistent with the hydrodynamic case and previously reported measurements.

Spence, E. J.; Roach, A. H.; Edlund, E. M.; Sloboda, P.; Ji, H. [Center for Magnetic Self-Organization in Laboratory and Astrophysical Plasmas and Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)

2012-05-15

43

Free MHD Shear Layers In The Presence Of Rotation And Magnetic Field  

SciTech Connect

We present an experimental and numerical study of hydrodynamic and magnetohydrodynamic free shear layers and their stability. We first examine the experimental measurement of globally unstable hydrodynamic shear layers in the presence of rotation, and their range of instability. These are compared to numerical simulations, which are used to explain the modification of the shear layer and thus the critical Rossby number for stability. Magnetic fields are then applied to these scenarios, and globally unstable magnetohydrodynamic shear layers generated. These too are compared to numerical simulations, showing behavior consistent with the hydrodynamic case and previously reported measurements.

E.J. Spence, A.H. Roach, E.M. Edlund, P. Sloboda and H. Ji

2012-03-20

44

Near-Earth wave propagation characteristics of electric dipole in presence of vegetation or snow layer  

Microsoft Academic Search

The problem of near-earth wave propagation in the presence of a dielectric layer such as a vegetation or snow covering is considered in this paper by modeling the propagation environment as a homogeneous two-layer medium (air\\/dielectric\\/ground). A number of studies have demonstrated the relevancy of the lateral wave for the case when both the transmitter and receiver are located within

DaHan Liao; Kamal Sarabandi

2005-01-01

45

Accretion onto neutron stars with the presence of a double layer  

NASA Technical Reports Server (NTRS)

It is known, from laboratory experiments, that double layers will form in plasmas, usually in the presence of an electric current. It is argued that a double layer may be present in the accretion column of a neutron star in a binary system. It is suggested that the double layer may be the predominant deceleration mechanism for the accreting ions, especially for sources with X-ray luminosities of less than about 10 to the 37th erg/s. Previous models have involved either a collisionless shock or an assumed gradual deceleration of the accreting ions to thermalize the energy of the infalling matter.

Williams, A. C.; Weisskopf, M. C.; Elsner, R. F.; Darbro, W.; Sutherland, P. G.

1987-01-01

46

Accretion onto neutron stars with the presence of a double layer  

NASA Technical Reports Server (NTRS)

It is known from laboratory experiments that double layers can form in plasmas, usually in the presence of an electric current. It is argued that a double layer may be present in the accretion column of a neutron star in a binary system. It is suggested that the double layer may be the predominant deceleration mechanism for the accreting ions, especially for sources with X-ray luminosities of less than about 10 to the 37th erg/s. Previous models have involved either a collisionless shock or an assumed gradual deceleration of the accreting ions to thermalize the energy of the infalling matter.

Williams, A. C.; Weisskopf, M. C.; Elsner, R. F.; Darbro, W.; Sutherland, P. G.

1986-01-01

47

Seasonally active frost-dust avalanches on a north polar scarp of Mars captured by HiRISE  

E-print Network

Seasonally active frost-dust avalanches on a north polar scarp of Mars captured by HiRISE Patrick, P., et al. (2008), Seasonally active frost-dust avalanches on a north polar scarp of Mars captured-rich layers of the north polar layered deposits (NPLD) with varying dust content. Mars Orbiter Laser Altimeter

Byrne, Shane

48

Diffusion bonding of stainless steel to Zircaloy4 in the presence of a Ta intermediate layer  

Microsoft Academic Search

Diffusion bonding of stainless steel to Zircaloy-4 in the presence of Ta as interlayer has been investigated using diffusion couples heat treated at 1150 °C under vacuum for 3 h. Different types of regions have been observed in stainless steel, Zircaloy-4 and Ta foil. A Cr rich layer formed in stainless steel is found to act as a diffusion barrier.

M. Ahmad; J. I. Akhter; Q. Zaman; M. A Shaikh; M. Akhtar; M. Iqbal; E. Ahmed

2003-01-01

49

Device for determining frost depth and density  

NASA Technical Reports Server (NTRS)

A hand held device having a forward open window portion adapted to be pushed downwardly into the frost on a surface, and a rear container portion adapted to receive the frost removed from the window area are described. A graph on a side of the container enables an observer to determine the density of the frost from certain measurements noted. The depth of the frost is noted from calibrated lines on the sides of the open window portion.

Huneidi, F.

1983-01-01

50

6, 1105111066, 2006 Sea ice, frost flowers  

E-print Network

ACPD 6, 11051­11066, 2006 Sea ice, frost flowers and halogen activation W. R. Simpson et al. Title than potential frost flower contact W. R. Simpson 1 , D. Carlson 1 , G. Hoenninger 1,2, , T. A. Douglas. Simpson (ffwrs@uaf.edu) 11051 #12;ACPD 6, 11051­11066, 2006 Sea ice, frost flowers and halogen activation

Paris-Sud XI, Université de

51

FROST: Revisited and Distributed Vincent Poirriez  

E-print Network

FROST: Revisited and Distributed Vincent Poirriez LAMIH UVHC,UMR CNRS 8530 59313 Valenciennes de la Recherche FROST: Revisited and Distributed Vincent Poirriez HICOMB'05:April 04, 2005 #12;Protein Threading Problem Associate a protein sequence to an already known 3D structure. FROST: Revisited

Singer, Daniel

52

Presence and function of a thick mucous layer rich in polysaccharides around Bacillus subtilis spores.  

PubMed

This study was designed to establish the presence and function of the mucous layer surrounding spores of Bacillus subtilis. First, an external layer of variable thickness and regularity was often observed on B. subtilis spores. Further analyses were performed on B. subtilis 98/7 spores surrounded by a thick layer. The mechanical removal of the layer did not affect their resistance to heat or their ability to germinate but rendered the spore less hydrophilic, more adherent to stainless steel, and more resistant to cleaning. This layer was mainly composed of 6-deoxyhexoses, ie rhamnose, 3-O-methyl-rhamnose and quinovose, but also of glucosamine and muramic lactam, known also to be a part of the bacterial peptidoglycan. The specific hydrolysis of the peptidoglycan using lysozyme altered the structure of the required mucous layer and affected the physico-chemical properties of the spores. Such an outermost mucous layer has also been seen on spores of B. licheniformis and B. clausii isolated from food environments. PMID:25115519

Faille, Christine; Ronse, Annette; Dewailly, Etienne; Slomianny, Christian; Maes, Emmanuel; Krzewinski, Frédéric; Guerardel, Yann

2014-01-01

53

Layer formation on metal surfaces in lead-bismuth at high temperatures in presence of zirconium  

NASA Astrophysics Data System (ADS)

If the operating temperature lead-bismuth cooled fission reactor could be extended to 800 °C, they could produce hydrogen directly from water. A key issue for the deployment of this technology at these temperatures is the corrosion of the fuel cladding and structural materials by the lead-bismuth. Corrosion studies of several metals were performed to correlate the interaction layer formation rate as a function of time, temperature, and alloy compositions. The interaction layer is defined as the narrow band between the alloy substrate and the solidified lead-bismuth eutectic on the surface. Coupons of HT-9, 410, 316L, and F22 were tested at 550 and 650 °C for 1000 h inside a zirconium corrosion cell. The oxygen potential ranged from approximately 10 -22 to 10 -19 Pa. Analyses were performed on the coupons to determine the depth of the interaction layer and the composition, at each time step (100, 300, and 1000 h). The thickness of the interaction layer on F22 at 550 °C was 25.3 ?m, the highest of all the alloys tested, whereas at 650 °C, the layer thickness was only 5.6 ?m, the lowest of all the alloys tested. The growth of the interaction layer on F22 at 650 °C was suppressed, owing to the presence of Zr (at 1500 wppm) in the LBE. In the case of 316L, the interaction layers of 4.9 and 10.6 ?m were formed at 550 and 650 °C, respectively.

Loewen, Eric P.; Yount, Hannah J.; Volk, Kevin; Kumar, Arvind

2003-09-01

54

Field measurements of frost penetration into a landfill cover that uses a paper sludge barrier  

SciTech Connect

Frost penetration is a major environmental concern in landfill design. Freezing and thawing cycles may deteriorate the permeability of the liner or cap. In this study, the depth of frost penetration into a landfill cover that uses paper sludge as the impermeable barrier (the Hubbardston landfill in Massachusetts) was measured using a frost measurement system. A thermistor probe measured the temperature at various depths. Although temperature measurements are important, soil resistivity measurements are required to accurately predict the freezing level, since soil resistivity increases greatly upon freezing. A conductivity probe measured the half-bridge voltage between conductivity rings and a ground rod. Data were collected in data loggers. The data collected from 1992--1996 showed that the frost level did not penetrate the paper sludge capping layer. Heavy snow cover throughout the winters decreased the depth of frost penetration by insulating the landfill. The high water content in the sludge also contributed to the lack of freezing.

Moo-Young, H.K.; LaPlante, C.; Zimmie, T.F.; Quiroz, J.

1999-07-01

55

Frost as a first wall for the ICF laboratory microfusion facility  

SciTech Connect

The authors introduce the concept of using frost as the first wall of the ICF Laboratory Microfusion Facility being designed to produce 200-1000 MJ of thermonuclear yield. They present one design incorporating 2cm of frost deposited at 0.1 g/cm/sup 3/ on an LN-cooled fiber-reinforced polymer substrate. They calculate that such a frost layer will protect the substrate from ablation by target x rays and debris, and from shock-induced spallation. Postshot washdown with water should permit low-activation operation, and should preserve the original wall properties. The authors expect the impact of the frost on laser optics to be minimal, and expect the preshot lifetime of thermally unprotected cryogenic targets to be extended by operating the wall at 100-150 K. Moreover, they believe that such a frost first wall involves little technical risk, and will be inexpensive to construct and operate.

Orth, C.D.

1989-03-01

56

Frost as a first wall for the ICF Laboratory Microfusion Facility  

SciTech Connect

We introduce the concept of using frost as the first wall of the ICF Laboratory Microfusion Facility being designed to produce 200--1000 MJ of thermonuclear yield. We present one design incorporating 2 cm of frost deposited at 0.1 g/cm/sup 3/ on an LN-cooled fiber-reinforced polymer substrate. We calculate that such a frost layer will protect the substrate from ablation by target x rays and debris, and from shock-induced spallation. Postshot washdown with water should permit low-activation operation, and should preserve the original wall properties. We expect the impact of the frost on laser optics to be minimal, and expect the preshot lifetime of thermally unprotected cryogenic targets to be extended by operating the wall at 100-150 K. Moreover, we believe that such a frost first wall will involve little technical risk, and will be inexpensive to construct and operate. 4 refs., 1 fig.

Orth, C.D.

1988-11-15

57

Cave development by frost weathering  

NASA Astrophysics Data System (ADS)

This paper deals with the description and genesis of a special type of shelter cave. In German they are termed Auswitterungshöhlen which goes back to the 19th century and the genesis is supposed to be related to frost weathering, but to our knowledge, detailed studies are missing so far. This type of cave is very common in the area of investigation that comprises pre-Alpine and Alpine regions in the north-eastern part of the Eastern Alps: They make up 32% of the 5138 registered caves but surprisingly they entirely developed in carbonate rocks. Although most of them are smaller than a dozen metres, some have lengths of more than 50 m and entrances can be more than 100 m wide or similarly high. Besides general observations that lead to a list of characteristics for these caves, two of them in a pre-Alpine setting were studied in-depth. A detailed map, descriptions, and measurements concerning cave morphology, host rock geology, and climate are given. The thickness and composition of clastic sediments were investigated by small trenches and electric resistivity measurements. Sediment thicknesses reach up to 2 m inside the caves and below the entrances. For one year nets were installed to measure rockfall in both caves. In warm periods generally less than 5 g/month of debris could be collected, but a few 100 g/month for frost periods. This strong correlation and the significant amount of debris together with other observations suggest that frost weathering is an on-going and very important process for the formation of these caves. Grain-size distribution of the collected debris argues for the activity of both microgelivation and ice segregation. Therefore we suggest that the term frost weathering caves should be used for shelter caves whose genesis is related to frost weathering. As dissolution seems to be of marginal importance for the genesis they are a paradox as they develop in karstic rock but have pseudokarst features.

Oberender, Pauline; Plan, Lukas

2015-01-01

58

Transition of boundary layer flows in the presence of Goertler vortices  

Microsoft Academic Search

Transition of boundary layer flows in the presence of longitudinal counter-rotating Goertler vortices was experimentally investigated on a concave surface of 1.0 m radius of curvature in a perspex (plexiglass) curved rectangular duct connected to a low speed wind tunnel for a free-stream velocity range of 5.7-11.8 m\\/s. Quantitative measurements were carried out using a single sensor hot-wire anemometer, while

S. H. Winoto; H. T. Low

1989-01-01

59

Mapping of water frost and ice at low latitudes on Mars  

NASA Astrophysics Data System (ADS)

This paper reports on mapping of water frost and ice on Mars, in the range of latitudes between 30°S and 30°N. The study has been carried out by analysing 2485 orbits acquired during almost one martian year by the Mars Express/OMEGA imaging spectrometer. Water frost/ice is identified by the presence of ˜1.5 ?m, ˜2 ?m and ˜3.0 ?m absorptions. Although the orbits analysed in this study cover all seasons, water frost/ice is observed only near the aphelion seasons, at Ls = 19° and at Ls = 98-150°. Water frost/ice is detected mainly on the southern hemisphere between 15°S and 30°S latitude while it has not been identified within 15°S-15°N. In the northern hemisphere, the water frost/ice detection is complicated by the presence of clouds. Usually, water frost/ice is found in shadowed areas, while in few cases it is exposed to the sunlight. This indicates a clear relationship with the local illumination conditions on the slopes which favour the water frost/ice deposition on the surface when the temperatures are very low. OMEGA observations span from 10 to 17 LT and the frost/ice is detected mainly between 15 and 16 LT, with practically no detection before 13 LT. We think this is due to the fact that the 10-12 LT observations occur at large distances and it is not a local time effect. A thermal model is used to determine the deposition conditions on the sloped surfaces where water frost/ice has been found. There, daily atmospheric saturation does not occur on pole facing 10-25° slopes with current water vapour abundances but only by assuming values greater than 40 pr ?m. Moreover, the water frost/ice is not detected during the northern winter, even if the thermal model foresees daily saturation on 25° slopes.

Carrozzo, F. G.; Bellucci, G.; Altieri, F.; D'Aversa, E.; Bibring, J.-P.

2009-10-01

60

Layer Formation On Metal Surfaces In Lead-Bismuth At High Temperatures In Presence Of Zirconium  

SciTech Connect

If the operating temperature lead–bismuth cooled fission reactor could be extended to 800 °C, they could produce hydrogen directly from water. A key issue for the deployment of this technology at these temperatures is the corrosion of the fuel cladding and structural materials by the lead–bismuth. Corrosion studies of several metals were performed to correlate the interaction layer formation rate as a function of time, temperature, and alloy compositions. The interaction layer is defined as the narrow band between the alloy substrate and the solidified lead–bismuth eutectic on the surface. Coupons of HT-9, 410, 316L, and F22 were tested at 550 and 650 °C for 1000 h inside a zirconium corrosion cell. The oxygen potential ranged from approximately 10-22 to 10-19 Pa. Analyses were performed on the coupons to determine the depth of the interaction layer and the composition, at each time step (100, 300, and 1000 h). The thickness of the interaction layer on F22 at 550 °C was 25.3 µm, the highest of all the alloys tested, whereas at 650 °C, the layer thickness was only 5.6 µm, the lowest of all the alloys tested. The growth of the interaction layer on F22 at 650 °C was suppressed, owing to the presence of Zr (at 1500 wppm) in the LBE. In the case of 316L, the interaction layers of 4.9 and 10.6 µm were formed at 550 and 650 °C, respectively.

Loewen, Eric Paul; Yount, Hannah J.; Volk, Kevin; Kumar, Arvind

2003-09-01

61

Mapping Statistical Characteristics of Frosts in Iran  

NASA Astrophysics Data System (ADS)

To model and map the statistical characteristics of frost in Iran, the data related to the minimum daily temperature for a 15-year period (1990-2005) was obtained from Iran Meteorological Organization. Then using multivariate regression models, the relationship among five statistical characteristics, i.e. the mean Julian day of the first frost, mean Julian day of the last frost, mean number of frost days per year, mean length of the frost period and mean length of growing season were modeled by three geo - climate factors: elevation, longitude and latitude. The precision of each model was explored using four hypotheses: linearity of the relationship between independent variables and the dependent variable, normality of errors, constancy of error variance and lake of correlation of errors were tested, and their precisions were confirmed. At the second stage, contour lines resulting from STRM were converted to the point features class. Altogether, 661 474 points were gathered from all over Iran. Then, the studied five frost characteristics were generalized to 661 474 points; then, the regionalization maps of statistical characteristics of frost were obtained for Iran using Kriging interpolation method. The results showed that the temperature of highland areas above 4200 m above sea level always was at least zero and below zero during the year, and also the coastal strip of southern Iran had no frost. Elevation was the most effective factor in the spatial arrangement for the frequency of occurrence of Julian day of the first frost. The most effective factors in spatial arrangement for the frequency of occurrence of Julian day of the last frost, length of frost period and length of growing season were elevation and latitude. Finally, spatial arrangement for the frequency of occurrence of the frost days was also a function of three factors of elevation, longitude and latitude. The dominant role of elevation in spatial arrangement for the occurrence of the first frost day in Iran showed that the occurrence of the first frost day in Iran could be of the type of radiation frosts and the dominant role of elevation and latitude demonstrated that late-winter frosts can be mostly of the type of advection frosts. Therefore, arrangement of statistical features of frost in Iran is both a function of geo - climate factors and the synoptic systems which have entered the country.

Mahmoudi, P.

2014-10-01

62

Anhydrous Ammonia Frost on Titan  

NASA Astrophysics Data System (ADS)

Ammonia has been suggested as a probable source for sustaining Titan's thick nitrogen-dominated atmosphere. Ammonia is believed to be important to maintaining nitrogen in Titan's atmosphere. Ammonia is seen in clouds in the atmospheres of Jupiter and Saturn, but has yet to be detected on any of the satellites. This may be because all forms of NH3 are unstable in the ambient conditions of the satellites surfaces or that its spectral features are altered by other components of the surface, and have not been identified. It has recently been demonstrated[1] that brightening occurs in Titan’s atmosphere that is transient on the time-scale of months. The spectral shape of the brightening is more consistent with that of the transient apparition of a pure ammonia frost than of an ammonia monohydrate or ammonia dihydrate frost. However, the phase behavior of the ammonia water system has peritectics at compositions of 1:1 and 1:2. These hydrate forms would be expected to dominate if the frost, or the reservoir from which the frost was derived had any water present. Physical mechanisms for producing measurable quanitities of anhydrous ammonia can include chemical dehydration or dehydration of the vapor phase - but it is challenging to store significant quantities of the anhydrous material because of the phase behavior in the solid state. [1] Nelson, R.M., et al. Saturn’s Titan: Surface Change, Ammonia, and Implications for Atmospheric and Tectonic Activity., Icarus, 199, pp. 429-441, 2009 This work was performed at JPL under contract to NASA

Smythe, W. D.; Nelson, R.; Boryta, M. D.

2009-12-01

63

Ion-acoustic double layers in the presence of plasma source  

SciTech Connect

Steady-state plasma turbulence and formation of negative potential spikes and double layers in the presence of ion acoustic instabilities have been studied by means of one-dimensional particle simulations in which velocities of a small fraction of electrons are replaced by the initial drifting Maxwellian at a constant rate. A steady state is found where negative potential spikes appear randomly in space and time giving rise to an anomalous resistivity much greater than previously found. Comparisons of the simulation results with laboratory and space plasmas are discussed.

Okuda, H.; Ashour-Abdalla, M.

1981-11-01

64

Transition of boundary layer flows in the presence of Goertler vortices  

Microsoft Academic Search

Transition of boundary layer flows in the presence of longitudinal counter-rotating Goertler vortices was experimentally investigated\\u000a on a concave surface of 1.0 m radius of curvature in a perspex (plexiglass) curved rectangular duct connected to a low speed\\u000a wind tunnel for a free-stream velocity range of 5.7–11.8 m\\/s. Quantitative measurements were carried out using a single sensor\\u000a hot-wire anemometer, while

S. H. Winoto; H. T. Low

1989-01-01

65

Unexpected Presence of Graminan- and Levan-Type Fructans in the Evergreen Frost-Hardy Eudicot Pachysandra terminalis (Buxaceae): Purification, Cloning, and Functional Analysis of a 6-SST/6-SFT Enzyme1[W  

PubMed Central

About 15% of flowering plants accumulate fructans. Inulin-type fructans with ?(2,1) fructosyl linkages typically accumulate in the core eudicot families (e.g. Asteraceae), while levan-type fructans with ?(2,6) linkages and branched, graminan-type fructans with mixed linkages predominate in monocot families. Here, we describe the unexpected finding that graminan- and levan-type fructans, as typically occurring in wheat (Triticum aestivum) and barley (Hordeum vulgare), also accumulate in Pachysandra terminalis, an evergreen, frost-hardy basal eudicot species. Part of the complex graminan- and levan-type fructans as accumulating in vivo can be produced in vitro by a sucrose:fructan 6-fructosyltransferase (6-SFT) enzyme with inherent sucrose:sucrose 1-fructosyltransferase (1-SST) and fructan 6-exohydrolase side activities. This enzyme produces a series of cereal-like graminan- and levan-type fructans from sucrose as a single substrate. The 6-SST/6-SFT enzyme was fully purified by classic column chromatography. In-gel trypsin digestion led to reverse transcription-polymerase chain reaction-based cDNA cloning. The functionality of the 6-SST/6-SFT cDNA was demonstrated after heterologous expression in Pichia pastoris. Both the recombinant and native enzymes showed rather similar substrate specificity characteristics, including peculiar temperature-dependent inherent 1-SST and fructan 6-exohydrolase side activities. The finding that cereal-type fructans accumulate in a basal eudicot species further confirms the polyphyletic origin of fructan biosynthesis in nature. Our data suggest that the fructan syndrome in P. terminalis can be considered as a recent evolutionary event. Putative connections between abiotic stress and fructans are discussed. PMID:21037113

Van den Ende, Wim; Coopman, Marlies; Clerens, Stefan; Vergauwen, Rudy; Le Roy, Katrien; Lammens, Willem; Van Laere, André

2011-01-01

66

Winter frost at Viking Lander 2 site  

NASA Technical Reports Server (NTRS)

This paper presents quantitative evidence for cold trapping (frost redeposition) at the Viking Lander 2 site. This evidence consists of the frost surface coverage and color transition, the timing of this transition, and the limited vertical mixing and horizontal water transport. It is argued that cold trapping must be a general property of seasonal frost and, therefore, must be considered in order to understand the evolution of the surface environment of Mars.

Svitek, Thomas; Murray, Bruce

1990-01-01

67

Frost resistance in alpine woody plants.  

PubMed

This report provides a brief review of key findings related to frost resistance in alpine woody plant species, summarizes data on their frost resistance, highlights the importance of freeze avoidance mechanisms, and indicates areas of future research. Freezing temperatures are possible throughout the whole growing period in the alpine life zone. Frost severity, comprised of both intensity and duration, becomes greater with increasing elevation and, there is also a greater probability, that small statured woody plants, may be insulated by snow cover. Several frost survival mechanisms have evolved in woody alpine plants in response to these environmental conditions. Examples of tolerance to extracellular freezing and freeze dehydration, life cycles that allow species to escape frost, and freeze avoidance mechanisms can all be found. Despite their specific adaption to the alpine environment, frost damage can occur in spring, while all alpine woody plants have a low risk of frost damage in winter. Experimental evidence indicates that premature deacclimation in Pinus cembra in the spring, and a limited ability of many species of alpine woody shrubs to rapidly reacclimate when they lose snow cover, resulting in reduced levels of frost resistance in the spring, may be particularly critical under the projected changes in climate. In this review, frost resistance and specific frost survival mechanisms of different organs (leaves, stems, vegetative and reproductive over-wintering buds, flowers, and fruits) and tissues are compared. The seasonal dynamics of frost resistance of leaves of trees, as opposed to woody shrubs, is also discussed. The ability of some tissues and organs to avoid freezing by supercooling, as visualized by high resolution infrared thermography, are also provided. Collectively, the report provides a review of the complex and diverse ways that woody plants survive in the frost dominated environment of the alpine life zone. PMID:25520725

Neuner, Gilbert

2014-01-01

68

Frost resistance in alpine woody plants  

PubMed Central

This report provides a brief review of key findings related to frost resistance in alpine woody plant species, summarizes data on their frost resistance, highlights the importance of freeze avoidance mechanisms, and indicates areas of future research. Freezing temperatures are possible throughout the whole growing period in the alpine life zone. Frost severity, comprised of both intensity and duration, becomes greater with increasing elevation and, there is also a greater probability, that small statured woody plants, may be insulated by snow cover. Several frost survival mechanisms have evolved in woody alpine plants in response to these environmental conditions. Examples of tolerance to extracellular freezing and freeze dehydration, life cycles that allow species to escape frost, and freeze avoidance mechanisms can all be found. Despite their specific adaption to the alpine environment, frost damage can occur in spring, while all alpine woody plants have a low risk of frost damage in winter. Experimental evidence indicates that premature deacclimation in Pinus cembra in the spring, and a limited ability of many species of alpine woody shrubs to rapidly reacclimate when they lose snow cover, resulting in reduced levels of frost resistance in the spring, may be particularly critical under the projected changes in climate. In this review, frost resistance and specific frost survival mechanisms of different organs (leaves, stems, vegetative and reproductive over-wintering buds, flowers, and fruits) and tissues are compared. The seasonal dynamics of frost resistance of leaves of trees, as opposed to woody shrubs, is also discussed. The ability of some tissues and organs to avoid freezing by supercooling, as visualized by high resolution infrared thermography, are also provided. Collectively, the report provides a review of the complex and diverse ways that woody plants survive in the frost dominated environment of the alpine life zone. PMID:25520725

Neuner, Gilbert

2014-01-01

69

Robert Frost and the Poetry of Physics.  

ERIC Educational Resources Information Center

Examines five poems by Robert Frost that illustrate Frost's interest in science. The poems include allusions to renowned physicists, metaphoric descriptions of some famous physics experiments, explorations of complementarity as enunciated by Bohr, and poetic formulations of Heisenberg's uncertainty principle. (20 references) (MDH)

Coletta, W. John; Tamres, David H.

1992-01-01

70

FROST CONTROL IN THE PACIFIC NORTHWEST  

Technology Transfer Automated Retrieval System (TEKTRAN)

The basic physics of frost protection in orchards and vineyard in the Pacific Northewest USA are presented. Various frost protection techniques are discussed and compared. Potential emerging technologies in cold temperature modification are also discussed for potential applications in New Zealand k...

71

Mechanism of frost damage to concrete  

Microsoft Academic Search

We studied several topics that are important to explain the mechanisms of frost damage to concrete, including the volume change of concrete during freezing, the role of air voids in protecting concrete from frost damage, the pore structure of concrete, and the nucleation and propagation of ice in concrete. By combining calorimetric measurements with dilatometry, we were able to calculate

Zhenhua Sun

2010-01-01

72

Frost formation and ice adhesion on superhydrophobic surfaces  

E-print Network

We study frost formation and its impact on icephobic properties of superhydrophobic surfaces. Using an environmental scanning electron microscope, we show that frost nucleation occurs indiscriminately on superhydrophobic ...

Varanasi, Kripa K.

73

Diffusion bonding of stainless steel to Zircaloy-4 in the presence of a Ta intermediate layer  

NASA Astrophysics Data System (ADS)

Diffusion bonding of stainless steel to Zircaloy-4 in the presence of Ta as interlayer has been investigated using diffusion couples heat treated at 1150 °C under vacuum for 3 h. Different types of regions have been observed in stainless steel, Zircaloy-4 and Ta foil. A Cr rich layer formed in stainless steel is found to act as a diffusion barrier. A region observed with the Ta foil in Zircaloy-4 is rich in Cr, Ta, Fe and Zr while two zones are formed in Zircaoly-4 containing Zr, Ta, Cr, Fe and Ni. The zone rich in Zr gives black contrast and the other zone gives grey contrast and these are identified as eutectic phases of the type TaCr 2-Liq.-?-Zr and Ta(Cr,Fe) 2-Liq.-?-Zr.

Ahmad, M.; Akhter, J. I.; Zaman, Q.; Shaikh, M. A.; Akhtar, M.; Iqbal, M.; Ahmed, E.

2003-05-01

74

Frost heave induced mechanics of buried pipelines  

SciTech Connect

This paper examines the problem of the flexural interaction between a long-distance buried pipeline embedded in a soil medium that experiences differential frost heave. The modeling takes into consideration the interaction at a transition zone between a frozen region and a frost-susceptible region that experiences a time-dependent growth of a frost bulb around the buried pipeline. The heave that accompanies the development of a frost bulb induces the soil-pipeline interaction process. The analysis focuses on the development of a computational scheme that addresses the three-dimensional nature of the soil-pipeline interaction problem, the creep susceptibility of the frozen region, and a prescribed time- and stress-dependent heave in an evolving frost bulb zone. The numerical results presented in the paper illustrate the influence of the heave process and the creep behavior of the frozen soil on the displacements and stresses in the buried pipeline.

Selvadurai, A.P.S. [McGill Univ., Montreal, Quebec (Canada). Dept. of Civil Engineering; Shinde, S.B. [Canada Ltd., Calgary, Alberta (Canada). Engineering Research and Technology Div.

1993-12-01

75

Elevated Bacterial Abundance in Laboratory-Grown and Naturally Occurring Frost Flowers Under Late Winter Conditions  

NASA Astrophysics Data System (ADS)

Sea ice has been identified as an important microbial habitat, with bacteria and other microbes concentrated in the brine inclusions between ice crystals. Frost flowers, thought to draw brine from underlying sea ice, have not been characterized from a microbial standpoint. To test whether frost flowers serve as an upward vector of bacteria contained within sea ice brines we grew frost flowers in a freezer laboratory (air temperature of -21°C) from saline water spiked with the mesophilic (and thus passive under experimental conditions) bacterium Halomonas pacifica. Salinity of melted samples was measured and bacterial abundance determined by epifluorescent microscopy. Bacterial counts scaled to ice-melt volume averaged 2.82 x 106 ml-1 for frost flowers, compared to 9.47 x 105 ml-1 for underlying ice (3 x higher). Bacterial counts also correlated significantly with salinity (maximum value of 62.5 psu) for frost flowers, brine skim, and ice (df = 17, r = 0.59, p < 0.0001). Segregation coefficients were calculated to describe the efficiency of transport of both cells and salt from the starting solution into frost flowers. From these coefficients an enrichment index was calculated to test for bacterial concentration into frost flowers at a different rate than salt. Analysis with a Student’s T-test (df = 24, t = 0.306, p = .76) indicated that cells and salt were not transported into frost flowers with a significantly different efficiency. To test these findings in the field we then collected frost flowers (and related samples) from new sea ice near Barrow, Alaska in April 2009. Bacterial counts were significantly elevated (again, a 3-fold increase) in natural frost flowers (mean = 2.73 x 105 ml-1) compared to underlying sea ice (mean = 8.46 x 104 cells ml-1). For all field samples collected (frost flowers, underlying brine skim and sea ice, as well as snow), bacterial abundance correlated significantly with salinity (maximum value 124 psu, df = 40, r = 0.60, p < 0.0001). The presence of elevated numbers of bacteria in frost flowers may have implications for the previously observed chemical reactions that take place in them, especially if microbial activity can be shown to occur in this unique low temperature, low water activity microbial habitat.

Bowman, J. S.; Deming, J. W.

2009-12-01

76

Mars' Dynamic Albedo: Evidence for Widespread Seasonal Water Frost in the Northern Hemisphere from TES, HiRISE and THEMIS  

NASA Astrophysics Data System (ADS)

Using multi-year TES bolometric albedo and temperature data, we identify the presence of seasonal water frost on Mars. Our findings show a stark hemispherical asymmetry, consistent with our understanding of atmospheric water transport.

Bapst, J.; Bandfield, J. L.; Wood, S. E.

2014-07-01

77

Frost & Sullivan Press Release Published: 14 Dec 2006  

E-print Network

Frost & Sullivan Press Release Published: 14 Dec 2006 https://www.frost.com/prod/servlet/press-release.pag?mode=open&docid=89716687 Frost & Sullivan Honours Mobileye N.V. with the 2006 Entrepreneurial Company of the Year Award in the Automotive Industry LONDON - December 14, 2006 ­ Frost & Sullivan confers the 2006 Entrepreneurial Company

Shashua, Amnon

78

BEST PRACTICES RESEARCH 2010 Frost & Sullivan 1 "We Accelerate Growth"  

E-print Network

BEST PRACTICES RESEARCH © 2010 Frost & Sullivan 1 "We Accelerate Growth" New Product Innovation, Medical Diagnostics and Imaging Technology EU, 2010 Frost & Sullivan's Global Research Platform Frost manage growth, innovation and leadership. Based on the findings of this Best Practices research, Frost

79

BEST PRACTICES RESEARCH 2013 Frost & Sullivan 1 "We Accelerate Growth"  

E-print Network

BEST PRACTICES RESEARCH © 2013 Frost & Sullivan 1 "We Accelerate Growth" 201 3 2013 North American Mobile Workforce Management Product Line Strategy Award #12;BEST PRACTICES RESEARCH © 2013 Frost, 2013 Frost & Sullivan's Global Research Platform Frost & Sullivan is in its 50th year in business

Fisher, Kathleen

80

Quasi-two-layer finite-volume scheme for modeling shallow water flows with the presence of external forces  

E-print Network

Finite-volume numerical method for study shallow water flows over an arbitrary bed profile in the presence of external force is proposed. This method uses the quasi-two-layer model of hydrodynamic flows over a stepwise boundary with advanced consideration of the flow features near the step. A distinctive feature of the suggested model is a separation of a studied flow into two layers in calculating flow quantities near each step, and improving by this means approximation of depth-averaged solutions of the initial three-dimensional Euler equations. We are solving the shallow-water equations for one layer, introducing the fictitious lower layer only as an auxiliary structure in setting up the appropriate Riemann problems for the upper layer. Besides quasi-two-layer approach leads to appearance of additional terms in one-layer finite-difference representation of balance equations. These terms provide the mechanical work made by nonhomogeneous bed interacting with flow. A notable advantage of the proposed method is the consideration of the properties of the process of the waterfall, namely the fluid flow on the step in which the fluid does not wet part of the vertical wall of the step. The presence of dry zones in the vertical part of the step indicates violation of the conditions of hydrostatic flow. The quasi-two-layer approach determines the size of the dry zone of the vertical component of the step. Consequently it gives an opportunity to figure out the amount of flow kinetic energy dissipation on complex boundary. Numerical simulations are performed based on the proposed algorithm of various physical phenomena, such as a breakdown of the rectangular fluid column over an inclined plane, large-scale motion of fluid in the gravity field in the presence of Coriolis force over an mounted obstacle on underlying surface.

K. V. Karelsky; A. S. Petrosyan; A. G. Slavin

2011-01-17

81

Subharmonic excitation in amplitude modulation atomic force microscopy in the presence of adsorbed water layers  

NASA Astrophysics Data System (ADS)

In ambient conditions, nanometric water layers form on hydrophilic surfaces covering them and significantly changing their properties and characteristics. Here we report the excitation of subharmonics in amplitude modulation atomic force microscopy induced by intermittent water contacts. Our simulations show that there are several regimes of operation depending on whether there is perturbation of water layers. Single period orbitals, where subharmonics are never induced, follow only when the tip is either in permanent contact with the water layers or in pure noncontact where the water layers are never perturbed. When the water layers are perturbed subharmonic excitation increases with decreasing oscillation amplitude. We derive an analytical expression which establishes whether water perturbations compromise harmonic motion and show that the predictions are in agreement with numerical simulations. Empirical validation of our interpretation is provided by the observation of a range of values for apparent height of water layers when subharmonic excitation is predicted.

Santos, Sergio; Barcons, Victor; Verdaguer, Albert; Chiesa, Matteo

2011-12-01

82

Simulation of vertical incidence ionograms by ray tracing method in the presence of replacement layer and ionospheric trough  

Microsoft Academic Search

Theoretical ionograms in the presence of a replacement layer and an ionospheric trough are calculated using the ray tracing method. A versatile ionospheric model is applied. Two examples are given where the traces in the ionogram produced by oblique reflections at a horizontal electron density gradient show anomalous behavior. In one case the high frequency part and in the other

T. Nygren

1977-01-01

83

Frost streaks in the south polar cap of Mars  

NASA Technical Reports Server (NTRS)

Viking Orbiter images of the annual south polar cap on Mars exhibit elongated bright features that are associated with craters and resemble wind streaks observed elsewhere on Mars. The study focuses on the well-documented frost streaks. The discussion covers the morphology of frost streaks, occurrence, seasonal behavior, thickness of frost in streak deposits, wind patterns inferred from frost streaks and other eolian features in the south polar region, formation of frost streaks, and other locales of preferential frost accumulation. The form and seasonal behavior of the bright elongated albedo markings which extend from the rims of many craters in the south polar cap suggest that they are accumulations of CO2 frost in the lee of craters. The frost streaks appear in the fall, increasing in length but not changing in direction during fall and winter. The frost streaks indicate a prograde circulation pattern of near-surface winds around the pole. Other details are also presented.

Thomas, P.; Veverka, J.; Campos-Marquetti, R.

1979-01-01

84

An experimental investigation of the effect of hydrophobicity on the rate of frost growth in laminar channel flows  

SciTech Connect

An experimental investigation of the effect of the substrate on frost growth rate is presented. Measurements of frost height as a function of time are presented for a flat, bare, horizontally oriented aluminum substrate and four coated substrates, two hydrophilic and two hydrophobic. The average frost growth rate on the hydrophilic coated aluminum substrate is 13% higher than the control substrate, while the frost growth rate on the hydrophilic kapton substrate is 4% higher. Frost grows on the hydrophobic substrates at a rate 19% and 3% lower than the reference substrate for the polytetrafluoroethylene (PTFE) coated steel and PTFE tape, respectively. Differences in the receding and advancing contact angles for these substrates do not fully explain the difference in growth rates. Differences in initial water deposition, freezing, and frost growth on hydrophilic and hydrophobic substrates are examined using confocal microscopy. On the basis of the microscopic observations, the authors hypothesize that the water coverage on the substrate before and after freezing can affect the thermal resistance of the mature frost layer. Differences in thermal resistance, in turn, affect the growth rate.

Dyer, J.M.; Storey, B.D.; Hoke, J.L.; Jacobi, A.M.; Georgiadis, J.G.

2000-07-01

85

Laminar-specific distribution of zinc: evidence for presence of layer IV in forelimb motor cortex in the rat.  

PubMed

The rat is the most widely studied pre-clinical model system of various neurological and neurodegenerative disorders affecting hand function. Although brain injury to the forelimb region of the motor cortex in rats mostly induces behavioral abnormalities in motor control of hand movements, behavioral deficits in the sensory-motor domain are also observed. This questions the prevailing view that cortical layer IV, a recipient of sensory information from the thalamus, is absent in rat motor cortex. Because zinc-containing neurons are generally not found in pathways that run from the thalamus, an absence of zinc (Zn) in a cortical layer would be suggestive of sensory input from the thalamus. To test this hypothesis, we used synchrotron micro X-ray fluorescence imaging to measure Zn distribution across cortical layers. Zn maps revealed a heterogeneous layered Zn distribution in primary and secondary motor cortices of the forelimb region in the adult rat. Two wider bands with elevated Zn content were separated by a narrow band having reduced Zn content, and this was evident in two rat strains. The Zn distribution pattern was comparable to that in sensorimotor cortex, which is known to contain a well demarcated layer IV. Juxtaposition of Zn maps and the images of brain stained for Nissl bodies revealed a "Zn valley" in primary motor cortex, apparently starting at the ventral border of pyramidal layer III and ending at the close vicinity of layer V. This finding indicates the presence of a conspicuous cortical layer between layers III and V, i.e. layer IV, the presence of which previously has been disputed. The results have implications for the use of rat models to investigate human brain function and neuropathology, such as after stroke. The presence of layer IV in the forelimb region of the motor cortex suggests that therapeutic interventions used in rat models of motor cortex injury should target functional abnormalities in both motor and sensory domains. The finding is also critical for future investigation of the biochemical mechanisms through which therapeutic interventions can enhance neural plasticity, particularly through Zn dependent pathways. PMID:25192655

Alaverdashvili, Mariam; Hackett, Mark J; Pickering, Ingrid J; Paterson, Phyllis G

2014-12-01

86

Frost halos from supercooled water droplets  

PubMed Central

Water freezing on solid surfaces is ubiquitous in nature. Even though icing/frosting impairs the performance and safety in many processes, its mechanism remains inadequately understood. Changing atmospheric conditions, surface properties, the complexity of icing physics, and the unorthodox behavior of water are the primary factors that make icing and frost formation intriguing and difficult to predict. In addition to its unquestioned scientific and practical importance, unraveling the frosting mechanism under different conditions is a prerequisite to develop “icephobic” surfaces, which may avoid ice formation and contamination. In this work we demonstrate that evaporation from a freezing supercooled sessile droplet, which starts explosively due to the sudden latent heat released upon recalescent freezing, generates a condensation halo around the droplet, which crystallizes and drastically affects the surface behavior. The process involves simultaneous multiple phase transitions and may also spread icing by initiating sequential freezing of neighboring droplets in the form of a domino effect and frost propagation. Experiments under controlled humidity conditions using substrates differing up to three orders of magnitude in thermal conductivity establish that a delicate balance between heat diffusion and vapor transport determines the final expanse of the frozen condensate halo, which, in turn, controls frost formation and propagation. PMID:23012410

Jung, Stefan; Tiwari, Manish K.; Poulikakos, Dimos

2012-01-01

87

Wing laminar boundary layer in the presence of a propeller slipstream  

NASA Technical Reports Server (NTRS)

The effects of a propeller slipstream on the wing laminar boundary layer are being investigated. Hot-wire velocity sensor measurements have been performed in flight and in a wind tunnel. It is shown that the boundary layer cycles between a laminar state and a turbulent state at the propeller blade passage rate. The cyclic length of the turbulent state increases with decreasing laminar stability. Analyses of the time varying velocity profiles show the turbulent state to lie in a transition region between fully laminar and fully turbulent. The observed cyclic boundary layer has characteristics similar to relaminarizing flow and laminar flow with external turbulence.

Miley, S. J.; Howard, R. M.; Holmes, B. J.

1986-01-01

88

Numerical Study on Frost Profile over the Cooling Plate under Forced Convection  

NASA Astrophysics Data System (ADS)

This paper deals the numerical analysis on mass transfer under forced convection cooling. The transients of frost profiles on a cooling plat in a narrow channel were calculated by use of the packaged software with built in some original subroutines. In this paper, the architecture of these subroutines and this benchmark tests were showed. The calculation results exhibit local mass transfer rates and clarified following things. On the leading edge of the cooling plate, the frost accumulation accelerates locally. For the prediction on the cooling plate temperature distribution, to take into account latent heat of sublimation is necessary. In addition, the comparison between calculation and experimental results shows below issues. Both frost distribution profiles overlap in upstream; on the contrary, they do not overlap in the downstream. This comparison result indicates that the super saturation or mist flow is not negligible in the downstream. In terms of total frost weight, both results are roughly agreed and this weight increases proportionally with a run time despite increasing of the heat resistance caused by frost layer.

Kondou, Chieko; Senshu, Takao; Koyama, Shigeru; Kuwahara, Ken; Oguni, Kensaku

89

Effect of sodium monofluorophosphate treatment on microstructure and frost salt scaling durability of slag cement paste  

SciTech Connect

Sodium-monofluorophosphate (Na-MFP) is currently in use as a surface applied corrosion inhibitor in the concrete industry. Its basic mechanism is to protect the passive layer of the reinforcement steel against disruption due to carbonation. Carbonation is known as the most detrimental environmental effect on blast furnace slag cement (BFSC) concrete with respect to frost salt scaling. In this paper the effect of Na-MFP on the microstructure and frost salt scaling resistance of carbonated BFSC paste is presented. The results of electron microscopy, mercury intrusion porosimetry (MIP) and X-ray diffraction (XRD) are discussed. It is found that the treatment modifies the microstructure and improves the resistance of carbonated BFSC paste against frost salt attack.

Copuroglu, O. [Delft University of Technology, Faculty of CiTG, Micromechanics Laboratory (MICROLAB) (Netherlands)]. E-mail: o.copuroglu@citg.tudelft.nl; Fraaij, A.L.A. [Delft University of Technology, Faculty of CiTG, Materials Science and Sustainable Construction (Netherlands); Bijen, J.M.J.M. [Delft University of Technology, Faculty of CiTG, Materials Science and Sustainable Construction (Netherlands)

2006-08-15

90

Doctoral Defense "Frost Deterioration in Concrete Due to Deicer Salt Exposure  

E-print Network

Doctoral Defense "Frost Deterioration in Concrete Due to Deicer Salt Exposure: Mechanism-freeze climate zone. During winter a deicer-salt application is needed to melt snow on highways. Freezing in the presence of a deicer salt solution is considered a severe concrete exposure condition. Prolonged exposure

Kamat, Vineet R.

91

Performance of organic photovoltaic devices in the presence of buffer layers  

NASA Astrophysics Data System (ADS)

We have investigated the dependence of the efficiency improvement of organic photovoltaic devices on the buffer layer. A device with a three-layer structure of ITO/CuPc/C60/BCP/Al was made as a reference through a thermal evaporation method. Characteristic parameters of the photovoltaic devices were measured and analyzed. The obtained open-circuit voltage V OC , short-circuit current density J SC , fill factor (FF), and energy-conversion efficiency (ECE) for the reference device were 0.25 V, 1.05 mA/cm2, 0.45, and 0.12%, respectively. Also, devices with five-layer structures of ITO/PEDOT:PSS/CuPc/C60/BCP/(LiF or Cs2CO3)/Al were fabricated, and their electrical characteristics were measured. The V OC , J SC , FF, and ECE for the device with the LiF buffer layer were 0.47 V, 3.31 mA/cm2, 0.51, and 0.81%, and those obtained for the device with the Cs2CO3 buffer layer were 0.49 V, 3.52 mA/cm2, 0.53, and 0.92%, respectively. The photovoltaic performance of the device with the Cs2CO3 layer was found to be better than those of the others. The V OC , J SC , FF, and ECE for the device with the Cs2CO3 layer were higher than those of the reference device by factors of 1.88, 3.35, 1.18, and 7.67, respectively.

Kim, Tae-Wan; Shin, Jong-Yeol; Kang, Yong-Gil; Kim, Seung-Tae; Choi, Hyun-Min; Kim, Gwi-Yeol; Hong, Jin-Woong

2014-08-01

92

Design of UMTRA covers to mitigate the effect of frost penetration  

SciTech Connect

The Uranium Mill Tailings Remedial Action (UMTRA) Project, contracted by the US Department of Energy (DOE), requires construction of disposal cells for residual radioactive materials from abandoned uranium mill tailings. A disposal cell consists of contaminated material placed within a stabilized embankment with a top cover. The embankment and cover should be effective for up to 1000 years, to the extent reasonably achievable, and in any case for at least 200 years. The embankment cover usually consists of a radon/infiltration barrier, a frost barrier and erosion protection layer consisting of bedding and riprap layers. The radon/infiltration barrier and frost barrier are two important elements of the cover systems. A radon/infiltration barrier is designed to reduce the radon emissions from the contaminated materials and to limit the surface water infiltration into the contaminated material. However, a radon/infiltration barrier has to be protected from repeated freeze-thaw cycles to prevent an increase in permeability. Frost penetration depth is site specific and depends on local climatic conditions and soil properties of the cover system. However, placing a frost barrier is not only very costly but also reduces the disposal capacity of the embankment. Recent laboratory test results indicate that freeze-thaw cycles do not significantly effect the permeability of compacted sand-bentonite mixtures. Therefore, radon/infiltration barriers using sand-bentonite mixtures may not require frost barriers for protection against the effects of freeze-thaw. In this paper the design of UMTRA covers is briefly explained; the criteria to determine a 200 year freeze event, and the frost penetration depth are discussed. The results of freeze-thaw permeability tests on compacted clay and sand-bentonite mixtures are also presented.

Banani, A.M.; Claire, R.F.

1994-03-01

93

Perivascular Exudates in Frosted Branch Angiitis.  

PubMed

Three cases of young, minimally symptomatic patients found to have vitritis and extensive perivenous vitreous exudates resembling frosted branch angiitis are presented. Optical coherence tomography showed that these exudates appear to be extravascated from the vasculature. The material persisted over 1 year on immunosuppressive therapy, suggesting that its resolution should not be a treatment end point. These cases add to our understanding of the spectrum of clinical findings in frosted branch angiitis. [Ophthalmic Surg Lasers Imaging Retina. 2014;45:xxx-xxx.]. PMID:25215872

He, Lingmin; Moshfeghi, Darius M; Wong, Ira G

2014-09-18

94

Optical properties of polyimide layers prepared by vacuum deposition in the presence of gas  

NASA Astrophysics Data System (ADS)

Thin polyimide (PI) layers were prepared by simultaneous vacuum evaporation of the polyimide precursors pyromellitic dianhydride (PMDA) and 4,4'-oxydianiline (ODA). After deposition the layers were thermally treated 1 hour at 170°C followed by 1 hour at 250°C. Precursors were deposited in a residual atmosphere of different gases - argon, nitrogen, helium and air at a pressure 10?2 Pa. Conditions for fabrication of PI layers with reproducible composition, uniform and smooth surface, without mechanical and chemical defects have been established. It was found that the preparation conditions do not significantly affect the optical properties of the layers. The PI layers before and after thermal treatments are transparent over 85% in the studied spectral range (from 350 to 900 nm). The thermal treatment leads to a bathochromic shift, in a consequence of the transmission edge shift to the longer wavelengths, for all the samples, independently of the deposition conditions in the vacuum chamber. The average refractive indices at 633 nm varied from 1.67 towards 1.72 depending on the deposition conditions and thermal treatment.

Strijkova, V.; Danev, G.

2014-12-01

95

RESEARCH ARTICLE Conservation and genetics of the frosted flatwoods salamander  

E-print Network

RESEARCH ARTICLE Conservation and genetics of the frosted flatwoods salamander (Ambystoma species Á Flatwoods Introduction Flatwoods salamanders (Ambystoma cingulatum and A. bishopi) are endemic. bishopi, occurs west of the Apalachicola- Flint Rivers, while the frosted flatwoods salamander, A

Grether, Gregory

96

Evaluation of fin staging methods for minimizing coil frost accumulation  

E-print Network

Frost formation on heat pump evaporators is a source of degradation in the performance of heat pumps during heating mode operation. This research sought to determine whether staged fins on outdoor evaporators could slow the growth of frost...

Watters, Richard J.

2001-01-01

97

Measurements of thermal infrared spectral reflectance of frost, snow, and ice  

NASA Technical Reports Server (NTRS)

Because much of Earth's surface is covered by frost, snow, and ice, the spectral emissivities of these materials are a significant input to radiation balance calculations in global atmospheric circulation and climate change models. Until now, however, spectral emissivities of frost and snow have been calculated from the optical constants of ice. We have measured directional hemispherical reflectance spectra of frost, snow, and ice from which emissivities can be predicted using Kirchhoff's law (e = 1-R). These measured spectra show that contrary to conclusions about the emissivity of snow drawn from previously calculated spectra, snow emissivity departs significantly from blackbody behavior in the 8-14 micrometer region of the spectrum; snow emissivity decreases with both increasing particle size and increasing density due to packing or grain welding; while snow emissivity increases due to the presence of meltwater.

Salisbury, John W.; D'Aria, Dana M.; Wald, Andrew

1994-01-01

98

Layer formation on metal surfaces in lead–bismuth at high temperatures in presence of zirconium  

Microsoft Academic Search

If the operating temperature lead–bismuth cooled fission reactor could be extended to 800 °C, they could produce hydrogen directly from water. A key issue for the deployment of this technology at these temperatures is the corrosion of the fuel cladding and structural materials by the lead–bismuth. Corrosion studies of several metals were performed to correlate the interaction layer formation rate

Eric P Loewen; Hannah J Yount; Kevin Volk; Arvind Kumar

2003-01-01

99

BER and energy level performance of layered CDMA wireless sensor network in presence of correlated interferers  

Microsoft Academic Search

The paper evaluates the performance of a CDMA based wireless sensor networks (WSN) with layered architecture in terms of bit error rate (BER) and energy consumption for successful transmission of data packets. Correlation amongst signal and interferers in shadowed environment has been considered. Two kinds of interference namely multiple access interference (MAI) and node interference (NI) are considered. The bit

U. Datta; C. Kundu; S. Kundu

2009-01-01

100

Nonlinear unsteady contact heat conduction of two-layer shells in the presence of thermal radiation  

NASA Technical Reports Server (NTRS)

A technique is proposed for calculating the complex heat transfer of mated shells with the surrounding medium which also takes into account the temperature dependence of the contact thermal resistance between the shells. This technique can be used for thermal calculations and for calculations of the temperature stresses in two-layer space structure shells.

Novikov, V. S.; Chumakov, V. L.

1974-01-01

101

A Gentle Frost: Poet Helen Frost Talks about the Healing Power of Poetry and Her Latest Novel  

ERIC Educational Resources Information Center

This article presents an interview with poet Helen Frost. Frost talked about how poetry can help at-risk children. She also related the challenges she faced when she wrote her latest book titled "The Braid."

Margolis, Rick

2006-01-01

102

ORIGINAL PAPER Drought and frost resistance of trees: a comparison  

E-print Network

ORIGINAL PAPER Drought and frost resistance of trees: a comparison of four species at different /Published online: 1 December 2011 # INRA / Springer-Verlag France 2011 Abstract & Context Drought and frost, the vulnerability to drought-induced embolism and frost resistance of four species were analysed, whereby different

Paris-Sud XI, Université de

103

Original article Impact of late frost on height growth  

E-print Network

Original article Impact of late frost on height growth in young sessile oak regenerations Hatem 16 June 1998) Abstract - The damage due to late frost during the 1995 and 1996 growing seasons at the beginning of the 1995 growing season. In 1995, frost occurred after the complete elongation of the growth

Paris-Sud XI, Université de

104

Original article Modelling the influence of winter frosts  

E-print Network

Original article Modelling the influence of winter frosts on the development of the stem canker on the disease development. A model describing the influence of winter frost on the evolution of the cankers for which the model predicted poor survival of the fungus. Quercus rubra / Phytophthora cinnamomi / frost

Boyer, Edmond

105

Bioinformatics Computational Journal: Victor Frost, Terry Clark, Susan Gauch,  

E-print Network

Bioinformatics Computational Journal: User Guide Victor Frost, Terry Clark, Susan Gauch, Gerald: User Guide Investigators Victor Frost Terry Clark Susan Gauch Gerald Lushington Gary Minden Staff, Kansas 66045 Phone: (785) 864-4833 FAX:(785) 864-7789 e-mail: frost@eecs.ku.edu http

Kansas, University of

106

Original article Growth-chamber trial on frost hardiness  

E-print Network

Original article Growth-chamber trial on frost hardiness and field trial on flushing of sessile oak frost on 1-year-old seedlings of 10 European sessile oak provenances at different stages of development for frost injuries was between -4 and -8 °C. Terminal buds, lammas shoots and secondary buds dehardened

Paris-Sud XI, Université de

107

CRRELREPORT98-4 Frost-Shielding Methodology and  

E-print Network

CRRELREPORT98-4 Frost-Shielding Methodology and Demonstration for Shallow Burial of Water and Sewer the maximum frost penetration depth can be expensive when difficult digging conditions are encountered-element program was devel- oped to model various subterranean heat-flow situa- tions. It was used to design frost

Horvath, John S.

108

SPECIALSPECIALREPORTREPORT97-197-1 Frost Shielding Protection of a  

E-print Network

SPECIALSPECIALREPORTREPORT97-197-1 Frost Shielding Protection of a Water Line, Berlin, New lines beneath the frost line in cold regions can be expensive when ledge or other difficult mate- rial was developed to predict frost penetration depth around buried utility pipelines. The program was How to get

Horvath, John S.

109

Nr. 25 / 2013 // 8. Februar 2013 Antrittsvorlesung Professor Frost  

E-print Network

S. 1 / 2 Nr. 25 / 2013 // 8. Februar 2013 Antrittsvorlesung Professor Frost: Die Entstehung von vor. Professor Dan Frost, Lehrstuhl für experimentelle Geowissenschaften am Bayerischen Geoinstut, hat, Pflanzen, Ozeanen und der Atmosphäre. Dan Frost ist allerdings am Kohlenstoffkreislauf, der innerhalb des

Ullmann, G. Matthias

110

Spatial and Temporal Patterns of Soil Frost in the  

E-print Network

1 Spatial and Temporal Patterns of Soil Frost in the Northern Midwest United States Tushar Sinha · Why is soil frost important ? · Objectives · Study area · Methodology · Results · Conclusions #12;3 Why is soil frost important ? · Soil ice reduces infiltration, cohesion and soil strength · Increases

Cherkauer, Keith

111

ORIGINAL PAPER Relationships between frost hardiness, root growth potential,  

E-print Network

ORIGINAL PAPER Relationships between frost hardiness, root growth potential, and photosynthesis in the mass of photosynthetically active foliage as a result of early frost may negatively affect the seedling photosynthesis varied with frost intensity and degree of needle hardening. The mass of new roots formed over a 21

Paris-Sud XI, Université de

112

ORIGINAL PAPER Growth and frost hardening of European aspen  

E-print Network

ORIGINAL PAPER Growth and frost hardening of European aspen and backcross hybrid aspen.V. 2011 Abstract & Introduction The interactive effects of water and nitrogen (N) on frost hardiness) supply influence the growth, bud phenology and frost hardening of seven young European aspen (Populus

Paris-Sud XI, Université de

113

Insulator (Heat and Frost). Occupational Analyses Series.  

ERIC Educational Resources Information Center

This analysis covers tasks performed by an insulator, an occupational title some provinces and territories of Canada have also identified as heat and frost insulator. A guide to analysis discusses development, structure, and validation method; scope of the occupation; trends; and safety. To facilitate understanding the nature of the occupation,…

McRory, Aline; Ally, Mohamed

114

Robert Frost and the American College.  

ERIC Educational Resources Information Center

The life and works of poet Robert Frost are examined for insights into his philosophy concerning higher education, particularly formal education, his own style of teaching, perceptions of the teacher's role within and outside the classroom, and the relationship between student and teacher. (Originally published in 1936) (MSE)

Newdick, Robert S.

1999-01-01

115

Robert Frost: Rural New England Teacher.  

ERIC Educational Resources Information Center

Examines Robert Frost's teaching career, which lasted from 1893 to 1912. Discusses his extreme dislike of teaching, resulting in nervous exhaustion on several occasions, and his teaching innovations, which involved students writing about their own experiences and ideas, and reading aloud for expression and the sound of language. (SV)

Hiss, Sheila M.

1989-01-01

116

Latest results from FROST at Jefferson Lab  

SciTech Connect

The spectrum of broad and overlapping nucleon excitations can be greatly clarified by use of a polarized photon beam incident on a polarized target in meson photoproduction experiments. At Jefferson Lab, a program of such measurements has made use of the Jefferson Lab FROzen Spin Target (FROST). An overview of preliminary results are presented.

Ritchie, Barry G. [Arizona State University

2014-06-01

117

Micropropagation of Frost-Resistant Eucalyptus1  

E-print Network

Micropropagation of Frost-Resistant Eucalyptus1 Michel Boulay2 For 10 years now, AFOCEL has silviculture. Eucalypt is a genus which is studied for 6 years. After research on micropropagation of very for supplying refo- restation plots or industrial nurseries. Micropropagation of eucalypts is not new. After

Standiford, Richard B.

118

Crop Conditions Frost Damage and Thinning  

E-print Network

1 Crop Conditions Frost Damage and Thinning Powdery Mildew of Apple Nova, Procure & Rubigan: In southern parts of the state, petal fall on apples has come and gone, and fruit are up to about the 12 mm buds can result in a full crop. Red Delicious seem to be the worst af- fected, with significant damage

Ginzel, Matthew

119

Autumn Frost, North Polar Sand Dunes  

NASA Technical Reports Server (NTRS)

Autumn in the martian northern hemisphere began around August 1, 1999. Almost as soon as northern fall began, the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) started documenting the arrival of autumn frost--a precursor to the cold winter that will arrive in late December 1999. The first features to become covered by frost were the sand dunes that surround the north polar ice cap. The dunes seen here would normally appear very dark--almost black--except when covered by frost. Why the dunes begin to frost sooner than the surrounding surfaces is a mystery: perhaps the dunes contain water vapor that emerges from the sand during the day and condenses again at night. This picture shows dunes near 74.7oN, 61.4oW at a resolution of about 7.3 meters (24 feet) per pixel. The area covered is about 3 km (1.9 mi) across and is illuminated from the upper right. The picture appears to be somewhat fuzzy and grainy because the dunes here are seen through the thin haze of the gathering north polar winter hood (i.e., clouds).

1999-01-01

120

Presence of intact intercellular lipid lamellae in the upper layers of the stratum corneum.  

PubMed

The epidermal permeability barrier necessary for terrestrial life resides in the intercellular spaces of the stratum corneum and is composed of lipids. Membrane coating granules (MCGs), small intracellular organelles found in the uppermost layers of the living epidermis, contain stacks of membranous disks which are extruded into the intercellular space and undergo both biochemical and physical changes to form the lipid sheets which constitute this barrier. Using ruthenium tetroxide as a secondary fixative, we are able to demonstrate stacks of lamellae filling the intercellular spaces in the uppermost layers of the stratum corneum. The structure of these lipid lamellae is consistent with the proposed derivation of MCG lipid disks and also suggests that the lipid bilayer adjacent to the corneocyte cell envelope may be assembled from lipids not derived from MCGs. PMID:3585055

Madison, K C; Swartzendruber, D C; Wertz, P W; Downing, D T

1987-06-01

121

Alternate dipping preparation of biomimetic apatite layers in the presence of carbonate ions.  

PubMed

The classical simulated body fluids method cannot be employed to prepare biomimetic apatites encompassing metallic ions that lead to very stable phosphates. This is the case for heavy metals such as uranium, whose presence in bone mineral after contamination deserves toxicological study. We have demonstrated that existing methods, based on alternate dipping into calcium and phosphate ions solutions, can be adapted to achieve this aim. We have also especially studied the impact of the presence of carbonate ions in the medium as these are necessary to avoid hydrolysis of the contaminating metallic cations. Both the apatite-collagen complex method and a standard chemical (STD) method employing only mineral solutions lead to biomimetic apatites when calcium and carbonate ions are introduced simultaneously. The obtained materials were fully characterized and we established that the STD method tolerates the presence of carbonate ions much better, and this leads to homogeneous samples. Emphasis was set on the repeatability of the method to ensure the relevancy of further work performed on series of samples. Finally, osteoblasts cultured on these samples also proved a similar yield and standard-deviation in their adenosine triphosphate content when compared to commercially available substrates designed to study of such cell cultures. PMID:24343417

Chatelain, Grégory; Bourgeois, Damien; Ravaux, Johann; Averseng, Olivier; Vidaud, Claude; Meyer, Daniel

2014-02-01

122

The Management of Extracellular Ice by Petioles of Frost-resistant Herbaceous Plants  

PubMed Central

• Background and Aims Some frost-tolerant herbaceous plants droop and wilt during frost events and recover turgor and posture on thawing. It has long been known that when plant tissues freeze, extracellular ice forms. Distributions of ice and water in frost-frozen and recovered petioles of Trifolium repens and Escholschzia californica were visualized. • Methods Petioles of intact plants were cryo-fixed, planed to smooth transverse faces, and examined in a cryo-SEM. • Key Results With frost-freezing, parenchyma tissues shrank to approx. one-third of their natural volume with marked cytorrhysis of the cells, and massive blocks of extracellular icicles grew under the epidermis (poppy) or epidermis and subepidermis (clover), leaving these layers intact but widely separated from the parenchyma except at specially structured anchorages overlying vascular bundles. On thawing, the extracellular ice was reabsorbed by the expanding parenchyma, and surface tissues again contacted the internal tissues at weak junctions (termed faults). These movements of water into and from the fault zones occurred repeatedly at each frost/thaw event, and are interpreted to explain the turgor changes that led to wilting and recovery. Ice accumulations at tri-cellular junctions with intercellular spaces distended these spaces into large cylinders, especially large in clover. Xylem vessels of frozen petioles were nearly all free of gas; in thawed petioles up to 20 % of vessels were gas-filled. • Conclusions The occurrence of faults and anchorages may be expected to be widespread in frost-tolerant herbaceous plants, as a strategy accommodating extracellular ice deposits which prevent intracellular freezing and consequent membrane disruption, as well as preventing gross structural damage to the organs. The developmental processes that lead to this differentiation of separation of sheets of cells firmly cemented at determined regions at their edges, and their physiological consequences, will repay detailed investigation. PMID:15355865

McCULLY, M. E.; CANNY, M. J.; HUANG, C. X.

2004-01-01

123

Anionexchange and thermal change of layered zinc hydroxides formed in the presence of Al(III)  

Microsoft Academic Search

Zinc hydroxide chloride particles of ZHC (simonkolleite, Zn5(OH)8Cl2·H2O) and layered double hydroxides (LDH, Zn–Al–Cl) were prepared by hydrolysis of ZnCl2 solutions dissolving AlCl3 at Al\\/Zn=0.1 and 0.6 in atomic ratio, respectively. The anion-exchange and thermal change of ZHC and LDH were investigated by XRD, TEM, FTIR, analysis of Zn, Al, and Cl and gas adsorption of N2, H2O, and CCl4.

Tatsuo Ishikawa; Kumi Matsumoto; Kazuhiko Kandori; Takenori Nakayama

2007-01-01

124

Reduced surface integral equations for Laplacian fields in the presence of layered bodies  

NASA Astrophysics Data System (ADS)

Laplacian potential fields in stratified media are usually analyzed using an integral equation for an unknown function over the union of all the interfaces between re-ions with different homogeneous materials. In this paper, the field problem is solved using a reduced integral equation involving a single unknown function over only the boundary of the source re,,ion. The new integral equation is derived by introducing Surface operators to express the potential and its normal derivative on each interface in terms of a single unknown function over the same interface. These operators and the corresponding single functions are obtained recursively, from one interface to the next. Thus, a Substantial decrease in the amount of necessary numerical computation and computer memory is achieved especially for systems containing, identical layered bodies where the reduction operators are Only Constructed for one of the bodies. The purpose of this paper is to derive reduced integral equations by directly applying the interface conditions and to show their high computational efficiency for systems of layered bodies.

Ciric, I. R.

2006-12-01

125

Study of Frost Properties in a Low Temperature Environment  

NASA Astrophysics Data System (ADS)

Performance of heat exchangers in appliances such as air-conditioners, showcase coolers and unit coolers can deteriorate under frosting conditions. To address this issue, the mechanism of frost deposition needs to be investigated. To achieve this goal, the frost formations process was observed and properties of frost were measured at air and cooling surface temperatures less than 0 °C using a refrigeration apparatus. Frost crystals formed on the cooling surface had a needle-like structure under the chilled condition, which represents an air temperature of 0 °C and cooling surface temperature of -10°C. On the other hand, frost crystals formed on cooling surface had a block shaped structure under the frozen condition, which represents an air temperature of -15°C and cooling surface temperature of -29°C. This work examined the relationship between density and thermal conductivity of frost, and calculated Nusselt number and Sherwood number.

Yamashita, Koji; Hamada, Mamoru; Ohkubo, Hidetoshi

126

Pluto: evidence for methane frost.  

PubMed

Infrared photometry (1.2 to 2.2 micrometers) of Pluto provides evidence for frozen methane on the surface of the planet. This appears to be the first observational indication of this ice in the solar system. Its presence on Pluto suggests that the planet's albedo (reflectance) may be >/= 0.4 and that its diameter may be less than that of the moon. PMID:17744185

1976-11-19

127

Long-time growth kinetics of first order phase transitions in the presence of a boundary layer.  

PubMed

The late stage growth mechanism for a first order phase transition, either through nucleation growth or spinodal decomposition, is well understood to be an Ostwald ripening or coarsening process, in which larger domains grow at the expense of smaller ones. The growth kinetics in this regime was shown by Lifshitz and Slyozov to follow at(1/3) law. However, the kinetics is altered if there exists a barrier ahead of the growth front, irrespective of the physical origin of the boundary layer. We present an analytic calculation for the growth kinetics in the presence of a boundary layer, showing that in the limit of barrier-dominated growth, the domains grow with at(1/2) law. This result holds true in the dilute regime independent of whether the growing nuclei are spherical or cylindrical. PMID:21280792

Mitra, Mithun K; Muthukumar, M

2011-01-28

128

GTD analysis of airborne antennas radiating in the presence of lossy dielectric layers  

NASA Technical Reports Server (NTRS)

The patterns of monopole or aperture antennas mounted on a perfectly conducting convex surface radiating in the presence of a dielectric or metal plate are computed. The geometrical theory of diffraction is used to analyze the radiating system and extended here to include diffraction by flat dielectric slabs. Modified edge diffraction coefficients valid for wedges whose walls are lossy or lossless thin dielectric or perfectly conducting plates are developed. The width of the dielectric plates cannot exceed a quarter of a wavelength in free space, and the interior angle of the wedge is assumed to be close to 0 deg or 180 deg. Systematic methods for computing the individual components of the total high frequency field are discussed. The accuracy of the solutions is demonstrated by comparisons with measured results, where a 2 lambda by 4 lambda prolate spheroid is used as the convex surface. A jump or kink appears in the calculated pattern when higher order terms that are important are not included in the final solution. The most immediate application of the results presented here is in the modelling of structures such as aircraft which are composed of nonmetallic parts that play a significant role in the pattern.

Rojas-Teran, R. G.; Burnside, W. D.

1981-01-01

129

Biocomplexity of Frost-Boil Ecosystems  

NSDL National Science Digital Library

The NSF-funded project seeks to understand the complex linkages between biogeochemical cycles, vegetation, disturbance, and climate across the full summer temperature gradient in the Arctic. Researchers examine the complexity associated with self-organization in frost-boil, complexity associated with interactions between biogeochemical cycles, cryoturbation, and vegetation, and biocomplexity across spatial-temporal scales. The web site includes the project proposal, research objectives, preliminary results, maps, photographs, data sets, and publications.

2003-01-01

130

Quasi-two-layer finite-volume scheme for modeling shallow water flows with the presence of external forces  

E-print Network

The numerical method for study of hydrodynamic flows over an arbitrary bed profile in the presence of external force is proposed in this paper. This method takes into account the external force effect, it uses the quasi-two-layer model of hydrodynamic flows over a stepwise boundary with consideration of features of the flow near the step. A distinctive feature of the proposed method is the consideration of the properties of the process of the waterfall, namely the fluid flow on the step in which the fluid does not wet part of the vertical wall of the step. The presence of dry zones in the vertical part of the step indicates violation of the conditions of hydrostatic flow. The quasi-two-layer approach allows to determine the size of the dry zone of the vertical component of the step. Consequently it gives an opportunity to figure out the amount of kinetic energy dissipation. There are performed the numerical simulations based on the proposed algorithm of various physical phenomena, such as a breakdown of the r...

Karelsky, K V; Slavin, A G

2011-01-01

131

www.frost.com US Machine-to-Machine (M2M) Communications  

E-print Network

www.frost.com US Machine-to-Machine (M2M) Communications Markets NC5E-65 #12;#NC5E-65 ©2013 Frost & Sullivan www.frost.com Frost & Sullivan takes no responsibility for any incorrect information supplied and therefore is subject to fluctuation. Frost & Sullivan reports are limited publications con- taining valuable

Fisher, Kathleen

132

Evolution of plant resistance and tolerance to frost Anurag A. Agrawal,1  

E-print Network

REPORT Evolution of plant resistance and tolerance to frost damage Anurag A. Agrawal,1 * Jeffrey K-season frost enabled us to estimate natural selection and genetic constraints on the evolution of frost found strong selection favouring plant resistance to frost, but selection against tolerance to frost

Stinchcombe, John

133

Frost growth and melting characteristics on glass fibers  

SciTech Connect

Frost growth over glass fibers of uniform diameter is observed using a microscope to investigate the cyclic effect of frosting and melting on the moisture accumulation in fiber-glass insulation, typically encountered in cold climate applications. A simple-three-dimensional conduction model is presented to demonstrate the temperature and local heat flux variation in the accumulated frost/water and attaching fibers. The numerical results show that the subcooling period for frost growth on fibers strongly depends on the fiber sizes and weakly depends on droplet sizes. For fiber diameters of greater than 0.23 mm, the local thermal equilibrium is no longer a good assumption.

Tao, Y.X. [Tennessee State Univ., Nashville, TN (United States). Dept. of Mechanical Engineering; Mao, Y.; Besant, R.W. [Univ. of Saskatchewan, Saskatoon, Saskatchewan (Canada). Dept. of Mechanical Engineering

1995-12-31

134

Laboratory evaluation of the effect of nitric acid uptake on frost point hygrometer performance  

NASA Astrophysics Data System (ADS)

Chilled mirror hygrometers (CMH) are widely used to measure water vapour in the troposphere and lower stratosphere from balloon-borne sondes. Systematic discrepancies among in situ water vapour instruments have been observed at low water vapour mixing ratios (<5 ppm) in the upper troposphere and lower stratosphere (UT/LS). Understanding the source of the measurement discrepancies is important for a more accurate and reliable determination of water vapour abundance in this region. We have conducted a laboratory study to investigate the potential interference of gas-phase nitric acid (HNO3) with the measurement of frost point temperature, and consequently the water vapour mixing ratio, determined by CMH under conditions representative of operation in the UT/LS. No detectable interference in the measured frost point temperature was found for HNO3 mixing ratios of up to 4 ppb for exposure times up to 150 min. HNO3 was observed to co-condense on the mirror frost, with the adsorbed mass increasing linearly with time at constant exposure levels. Over the duration of a typical balloon sonde ascent (90-120 min), the maximum accumulated HNO3 amounts were comparable to monolayer coverage of the geometric mirror surface area, which corresponds to only a small fraction of the actual frost layer surface area. This small amount of co-condensed HNO3 is consistent with the observed lack of HNO3 interference in the frost point measurement because the CMH utilizes significant reductions (>10%) in surface reflectivity by the condensate to determine H2O.

Thornberry, T.; Gierczak, T.; Gao, R. S.; Vömel, H.; Watts, L. A.; Burkholder, J. B.; Fahey, D. W.

2010-08-01

135

Laboratory evaluation of the effect of nitric acid uptake on frost point hygrometer performance  

NASA Astrophysics Data System (ADS)

Chilled mirror hygrometers (CMH) are widely used to measure water vapour in the troposphere and lower stratosphere from balloon-borne sondes. Systematic discrepancies among in situ water vapour instruments have been observed at low water vapour mixing ratios (<5 ppm) in the upper troposphere and lower stratosphere (UT/LS). Understanding the source of the measurement discrepancies is important for a more accurate and reliable determination of water vapour abundance in this region. We have conducted a laboratory study to investigate the potential interference of gas-phase nitric acid (HNO3) with the measurement of frost point temperature, and consequently the water vapour mixing ratio, determined by CMH under conditions representative of operation in the UT/LS. No detectable interference in the measured frost point temperature was found for HNO3 mixing ratios of up to 4 ppb for exposure times up to 150 min. HNO3 was observed to co-condense on the mirror frost, with the adsorbed mass increasing linearly with time at constant exposure levels. Over the duration of a typical balloon sonde ascent (90-120 min), the maximum accumulated HNO3 amounts were comparable to monolayer coverage of the geometric mirror surface area, which corresponds to only a small fraction of the actual frost layer surface area. This small amount of co-condensed HNO3 is consistent with the observed lack of HNO3 interference in the frost point measurement because the CMH utilizes significant reductions (>10%) in surface reflectivity by the condensate to determine H2O.

Thornberry, T.; Gierczak, T.; Gao, R. S.; Vömel, H.; Watts, L. A.; Burkholder, J. B.; Fahey, D. W.

2011-02-01

136

Experimental study of a turbulent boundary layer in presence of external manipulators of NACA 0009 profile in the transonic regime  

NASA Astrophysics Data System (ADS)

An experimental study was conducted to determine the effectiveness of manipulators of external-type turbulence on the reduction of wall drag in a turbulent boundary layer in the transonic regime. The manipulators used, NACA 0009 thin profile type, have an aerodynamic behavior inappropriate for this type of application. Flow visualizations show that the flow on the manipulator is complex, with regions of separation, as well as recirculation, and that the wake of the manipulator is sometimes very unstable. Some of such behavior may be the origin of the high levels of drag encountered and adversely affects the effectiveness of this method in the sense of net balance. The analysis of the average velocity profiles, downstream of the single manipulator, does not permit reaching definitive quantitative conclusions since it leads to abnormally high reductions of the coefficient of wall drag, due apparently to the presence of a longitudinal pressure gradient which was not considered in the equation of motion.

Poirier, Diane

1990-05-01

137

Geophysical Implications of Enceladus' CO2 Frost  

NASA Astrophysics Data System (ADS)

CO2 frost has been reported on the surface of Enceladus [1]. We suggest that the frost originated from shallow gas pockets below the surface. These pockets are a natural consequence of the ocean water circulation hypothesis [2]. They are different from the plume chambers [3] and would constitute a previously unrecognized structure in the surface. The oceanic circulation uses gas bubbles to make seawater buoyant and bring up water, chemicals, and heat from a warm ocean at depth [2]. The ocean water rises through the icy crust and near the surface it spreads out laterally beneath a relatively thin ice cap, following the pattern indicated by the thermal anomalies identified in Cassini data [4,5]. Topography on the bottom of this cap ice is conducive to the formation of gas pockets. As the ocean water flows horizontally, the gas bubbles in it continue to rise vertically. Even though their vertical migration may be slow and even if the flow is relatively turbulent, some bubbles reach recesses in the bottom of the ice cap and, over time, pop and form gas pockets. The gas pockets are envisioned as being ruptured by the regular fissuring of ice in the South Polar Region. Hurford et al. [6] have modelled the tidally controlled openings of rifts in the SPR. If one of these rifts reaches a gas pocket, CO2 gas may come to the surface. The tortuosity and other properties of its route will determine if it vents as a seep or a jet. If enough gas is vented and the molecules in the transient cloud have many collisions, some of them will be scattered to the surface and freeze. It was noted by Brown, et al. [1] that the frost deposits may not be permanent and that an active replenishment processes might be necessary. Studies of CO2 frost on Iapetus suggest that migration can be significant [7]. This work was performed at the Jet Propulsion Laboratory, California Institute of Technology, under contract to NASA. al., Science 311, 1425-1428, 2006. [2] Matson D. L. et al., Icarus 221, 53-62, 2012. (also see Matson et al. LPS 44 Abstract 1371, 2013). [3] Schmidt J. et al., Nature 451, 685-688, 2008. [4] Spencer J. R. et al., Science 311, 1401-1405, 2006. [5] Howett C. et al., JGR 116, E03003, 2011. [6] Hurford T. A. et al., Nature 447, 292-294, 2007. [7] Palmer E. E. and Brown R. H. Icarus 195, 434-446, 2008.

Matson, D.; Davies, A. G.; Johnson, T. V.; Castillo, J. C.; Lunine, J. I.

2013-12-01

138

Habitat characteristics of adult frosted elfins (Callophrys irus) in sandplain communities of southeastern Massachusetts, USA  

E-print Network

Habitat characteristics of adult frosted elfins (Callophrys irus) in sandplain communities 2006 Keywords: Frosted elfin Callophrys irus Butterfly conservation Sandplain communities Invasive-dependent Lepidop- tera within sandplain habitats of the northeastern United States. The frosted elfin (Calloph- rys

Schweik, Charles M.

139

The distribution of water frost on Charon  

NASA Technical Reports Server (NTRS)

We present high-spatial-resolution imaging observations of the Pluto-Charon system taken with ProtoCAM on the Infrared Telescope Facility (IRTF). Our dataset consists of measurements from eight nights at widely separated rotational longitudes and covering five wavelengths -- standard J, H, and K, plus two special narrow band filters at 1.5 and 1.75 microns. The relative flux contributions of Pluto and Charon were extracted, when possible, by fitting a two-source Gaussian image model to the observed images. At K, we find the Charon-Pluto magnitude difference to be on average 1.8 mag, somewhat less than the value of 2.2 mag found by Bosh et al. (1992). The average differential magnitude at 1.5 and 1.75 microns is 2.0 and 1.6, respectively. The larger magnitude difference at 1.5 microns is due to a water-frost absorption band on the surface of Charon. Our observations are consistent with a surface of Charon dominated by water frost at all longitudes.

Buie, Marc W.; Shriver, Scott K.

1994-01-01

140

Argon frost continuous cryopump for fusion applications  

SciTech Connect

A cryopumping system based on the snail continuous cryopump concept is being developed for fusion applications under a DOE SBIR grant. The primary pump is a liquid helium cooled compound pump designed to continuously pump and fractionate deuterium/tritium and helium. The D/T pumping stage is a 500 mm bore cryocondensation pump with a nominal pumping speed of 45,000 L/s. It will be continuously regenerated by a snail regeneration by head every 12 minutes. Continuous regeneration will dramatically reduce the vulnerable tritium inventory in a fusion reactor. Operating at an inlet pressure of 1 millitorr, eight of these pumps could pump the projected D/T flow in the ITER CDA design while reducing the inventory of tritium in the pumping system from 630 to 43 grams. The helium fraction will be pumped in a compound argon frost stage. This stage will also operate continuously with a snail regeneration head. In addition the argon spray head will be enclosed inside the snail, thereby removing gaseous argon from the process chamber. Since the cryocondensation stage will intercept over 90% of the D/T/H steam, a purified stream from this stage could be directly reinjected into the plasma as gas or pellets, thereby bypassing the isotope separation system and further simplifying the fuel cycle. Experiments were undertaken in Phase I which demonstrated continuous cryosorption pumping of hydrogen on CO{sub 2} and argon frosts. The pumping system and its relevance to fusion reactor pumping will be discussed.

Foster, C.A.; McCurdy, H.C.

1993-12-01

141

IRTM Observations of Martian South Polar Frosts  

NASA Astrophysics Data System (ADS)

The albedo is an important factor in the heat balance because it determines the amount of absorbed solar radation. This is of particular interest for the martian south polar cap, SPC, because the SPC is believed to be the primary carbon dioxide reservoir for the martian atmosphere. For frosts and ices, albedo information could also provide keys to the microphysical nature of the surface. The Viking Infrared Thermal Mapper, IRTM, made observations of the SPC throughout southern spring and summer. The full retreat of the seasonal cap was observed in detail. The dearth of more recent spacecraft observations of the SPC has led to a thorough re-analysis of these data, using current image processing and computational techniques. The following trends in the reflectivity of the SPC frost are reported here. Initially, in early southern spring, the seasonal cap has an albedo of roughly 0.45. This increases steadily and peaks at mid-summer, when the albedo reaches 0.7 in places. After this time, the seasonal cap sublimes away, leaving the residual cap which has an albedo of roughly 0.5. Furthermore, no evidence was seen for any albedo dependance on solar illumination, emission, azimuth angle, or on local time. Several current theories that attempt to explain the SPC reflectivity will be examined in light of this new analysis.

Ono, A. M.; Paige, D. A.

1996-06-01

142

Simulated frost effects on cool-season grass carbohydrate levels  

Technology Transfer Automated Retrieval System (TEKTRAN)

Anecdotal observations suggest increased incidences of metabolic problems in horses on pasture after a frost. The speculation is that frost increases the level of nonstructural carbohydrates (NSC) in cool-season grasses, which have been implicated in horse metabolic problems (e.g., laminitis). We co...

143

Frost Collection Presented to University of the Incarnate Word  

ERIC Educational Resources Information Center

On April 21, 2004, the Joe L. Frost Children's Play and Play Environments Research Collection was dedicated at the J.E. and L.E. Mabee Library at the University of the Incarnate Word, San Antonio, Texas. This brief article describes the collection and Frost's plans for the future.

Childhood Education, 2004

2004-01-01

144

Thermal resistance of frost on a finned air cooler  

SciTech Connect

This paper presents a method for measuring the thermal conductivity of frost accumulated on the fins of air conditioners and estimating the subsequent losses in thermal efficiency to the conditioner. The method is intended for use in optimizing the configuration of the fin design and working conditions of the conditioner for minimum frost accumulation and maximum defrost capacity.

Chepurnoi, M.N.; Shnaider, V.E.; Lomakin, V.N.; Sinyuk, N.I.

1987-09-01

145

Grammatical Categories in Robert Frost's Blank Verse: A Quantitative Analysis.  

ERIC Educational Resources Information Center

Structural linguistic techniques were utilized to categorize the grammatical elements employed by Robert Frost in 46 blank-verse poems. Nineteen main grammatical categories and 26 verb sub-categories based on distinctive selection criteria were devised to examine the range and distribution of Frost's grammatical patterns. Five control poems by E.…

Lyford, Roland Hazen

146

BEST PRACTICES RESEARCH 2013 Frost & Sullivan 1 "We Accelerate Growth"  

E-print Network

Award Video Conferencing Hosted and Managed Services North America, 2013 Frost & Sullivan's Global Research Platform Frost & Sullivan is in its 50th year in business with a global research organization of 1 American market leader can play an instrumental role in enabling interoperability among disparate solutions

Fisher, Kathleen

147

Genetically engineered microorganisms to rescue plants from frost injury  

Microsoft Academic Search

Ice nucleation active bacteria belonging to genera Pseudomonas, Xanthomonas and Erwinia contribute to frost damage to plants by initiating the formation of ice in plants that would otherwise supercool and avoid the damaging ice formation. The biological control of frost injury can be achieved by the application of non-ice nucleation active bacteria to the plant surfaces before they become colonized

G. H. Dar; R. C. Anand; P. K. Sharma

148

Transmission line corona losses under hoar frost conditions  

SciTech Connect

Transmission line corona losses under hoar frost conditions were studied in the climate room of the high voltage laboratory of Tampere University of Technology. The measurements were performed using a coaxial measurement arrangement with different bundle and conductor types. The effects of conductor and bundle type, temperature, applied voltage and hoar frost thickness on corona losses were investigated. A two-conductor bundle had corona losses about 2.5--5 times higher than a three-conductor bundle. Relatively thin hoar frosts were used in the tests. Even the thinnest hoar frost resulted in remarkable corona losses and the losses were very sensitive to changes in the hoar frost thickness. The ambient temperature had a strong influence on the measured losses.

Lahti, K.; Nousiainen, K. [Tampere Univ. of Technology (Finland). Power Engineering Group] [Tampere Univ. of Technology (Finland). Power Engineering Group; Lahtinen, M.

1997-04-01

149

Genetically engineered microorganisms to rescue plants from frost injury.  

PubMed

Ice nucleation active bacteria belonging to genera Pseudomonas, Xanthomonas and Erwinia contribute to frost damage to plants by initiating the formation of ice in plants that would otherwise supercool and avoid the damaging ice formation. The biological control of frost injury can be achieved by the application of non-ice nucleation active bacteria to the plant surfaces before they become colonized by Ice+ species. ice genes have been cloned from Pseudomonas and isogenic Ice- derivatives constructed via genetic manipulations. These genetically engineered microorganisms (GEMs) have been released into the environment to control the frost damage. The incidence of frost injury to the plants has, thereby, been reduced by 50-85% during natural frosts. These GEMs do not survive in soil and show no aerial dispersal in the environment. PMID:8213308

Dar, G H; Anand, R C; Sharma, P K

1993-01-01

150

Frost formation on an airfoil: A mathematical model 1  

NASA Technical Reports Server (NTRS)

A computer model to predict the frost formation process on a flat plate was developed for application to most environmental conditions under which frost occurs. The model was analytically based on a generalized frost thermal conductivity expression, on frost density and thickness rate equations, and on modified heat and mass transfer coefficients designed to fit the available experimental data. The broad experimental ranges reflected by the extremes in ambient humidities, wall temperatures, and convective flow properties in the various publications which were examined served to severely test the flexibility of the model. An efficient numerical integration scheme was developed to solve for the frost surface temperature, density, and thickness under the changing environmental conditions. The comparison of results with experimental data was very encouraging.

Dietenberger, M.; Kumar, P.; Luers, J.

1979-01-01

151

One: Microphysics of frost metamorphism: Applications to Triton and Mars. Two: A global analysis of the ozone deficit in the upper stratosphere and lower mesosphere. Three: The diabatic circulation in the stratosphere as diagnosed from Microwave Limb Sounder data  

SciTech Connect

The present thesis is devoted to two broad subjects, planetary frost metamorphism and the terrestrial middle atmosphere, and consists of three papers. Paper 1 considers frost metamorphism on the surfaces of Triton and Mars. Based on an analysis of the microphysical processes involved in the pressureless sintering, it is concluded that fine-grained nitrogen and carbon dioxide frosts can undergo seasonal metamorphism into semitransparent layers on the surface of Triton and in the Martian seasonal polar caps, respectively. The presence of such layers explains a host of facts about Triton's surface and about the Martian seasonal caps. Paper 2 is devoted to elucidating a long-standing issue in the terrestrial middle atmosphere chemistry, the so-called 'ozone deficit problem.' Based on an analysis of data acquired by the Limb Infrared Monitor of the Stratosphere (LIMS) instrument between October 1978 and May 1979, it is concluded that current photochemical models systematically underestimate observed ozone abundances in the upper stratosphere and lower mesosphere. Three modifications to the accepted photochemical scheme, capable of providing a global solution to this problem, are proposed and discussed. Paper 3 differs from the other two in that it reports on results from an ongoing research effort. It considers the diabatic circulation in the stratosphere and lower mesosphere, using ozone and temperature measurements acquired by the Microwave Limb Sounder (MLS) instrument onboard the Upper Atmosphere Research Satellite (UARS). The present study extends past analyses of the diabatic circulation by considering a full annual cycle, November 1991-November 1992, and by taking advantage of the high vertical resolution of MLS data. In the tropical upper stratosphere and lower mesosphere, a semiannual oscillation (SAO) is observed in the computed circulation, with the region of downwelling reaching maximum spatial extent approximately 1 month before the equinox.

Eluszkiewicz, J.B.

1993-01-01

152

Delayed frost growth on jumping-drop superhydrophobic surfaces.  

PubMed

Self-propelled jumping drops are continuously removed from a condensing superhydrophobic surface to enable a micrometric steady-state drop size. Here, we report that subcooled condensate on a chilled superhydrophobic surface are able to repeatedly jump off the surface before heterogeneous ice nucleation occurs. Frost still forms on the superhydrophobic surface due to ice nucleation at neighboring edge defects, which eventually spreads over the entire surface via an interdrop frost wave. The growth of this interdrop frost front is shown to be up to 3 times slower on the superhydrophobic surface compared to a control hydrophobic surface, due to the jumping-drop effect dynamically minimizing the average drop size and surface coverage of the condensate. A simple scaling model is developed to relate the success and speed of interdrop ice bridging to the drop size distribution. While other reports of condensation frosting on superhydrophobic surfaces have focused exclusively on liquid-solid ice nucleation for isolated drops, these findings reveal that the growth of frost is an interdrop phenomenon that is strongly coupled to the wettability and drop size distribution of the surface. A jumping-drop superhydrophobic condenser minimized frost formation relative to a conventional dropwise condenser in two respects: preventing heterogeneous ice nucleation by continuously removing subcooled condensate, and delaying frost growth by limiting the success of interdrop ice bridge formation. PMID:23286736

Boreyko, Jonathan B; Collier, C Patrick

2013-02-26

153

On turbulence modulation due to the presence of sediment in the bottom boundary layer - a numerical investigation  

NASA Astrophysics Data System (ADS)

One of the most intriguing issues in fine sediment transport, including turbidity currents, tidal-driven transport and wave-driven transport, is that the presence of sediments may lead to attenuation of flow turbulence. Depending on the level of turbulence suppression, it may lead to the formation of lutocline (a sharp negative sediment concentration) and an enhanced gravity flow; or it may cause catastrophic collapse of turbulence and sediment deposition. Through laboratory observations and numerical simulations, prior studies have established that these transitions can be caused by various degree of sediment-induced stable density stratification. However, when sediment concentration becomes larger, inter-particle (or inter-floc) interactions may lead to enhanced viscosity through rheological stress and its role on turbulence modulation is unclear. Through turbulence-resolving simulations, this study further investigates turbulence suppression due to enhanced effective viscosity via two simple Newtonian rheological closures in a steady channel flow and in an oscillatory bottom boundary layer. Assuming a small Stokes number, the Equilibrium approximation to the Eulerian two-phase flow equations is adopted. The resulting simplified equations are solved with a high-accuracy hybrid spectral-compact finite difference scheme in an idealized channel. The numerical approach extends an earlier pseudo-spectral model for direct numerical simulation (DNS) of turbulent flows with a sixth-order compact finite difference scheme in the wall-normal direction on Chebyshev grid points. The compact finite difference scheme allows easy implementation of concentration-dependent viscosity. Simulation results reveal that when rheological stress is incorporated, the enhanced effective viscosity can further attenuate flow turbulence in addition to the well-known sediment-induced stable density stratification. Through the enhanced viscosity, velocity gradient very near the bed is significantly reduced, which leads to much weaker turbulent production and the onset of laminarization. This mechanism is different from the sediment-induced density stratification that typically damps turbulence in the middle of the boundary layer where the lutocline is located. Our preliminary finding shows that rheology encourages laminarization may explain why large attenuation of surface waves over muddy seabed is ubiquitous and the highest dissipation rate is often observed during the waning stage of a storm.

Hsu, T.; Yu, X.; Ozdemir, C. E.; Balachandar, S.

2013-05-01

154

Aust. J. Agric. Res., 1993, 44, 1731-43 Characteristics of Frost in a Major  

E-print Network

Aust. J. Agric. Res., 1993, 44, 1731-43 Characteristics of Frost in a Major Wheat-growing Region, New Zealand. Abstract Frost at anthesis of wheat reduces grain set. Characteristics of frost, the region can be divided into four homogeneous areas according to five general characteristics of frost

Fletcher, David

155

Frost flower chemical composition during growth and its implications for aerosol production  

E-print Network

Frost flower chemical composition during growth and its implications for aerosol production; published 5 November 2008. [1] Frost flowers have been proposed to be the major source of sea-salt aerosol. Therefore, we chemically analyzed 28 samples of frost flowers and parts of frost flowers collected from sea

Douglas, Thomas A.

156

The SEI layer formed on lithium metal in the presence of oxygen: A seldom considered component in the development of the Li-O2 battery  

NASA Astrophysics Data System (ADS)

The SEI layer formed on metallic Li which has been used as an anode in a Li-O2 battery is studied for the first time. We have used XPS to monitor the surface composition of the lithium electrode and have identified the various chemical species present. The XPS results indicated that the composition of the SEI layer is affected by the presence of oxygen and is unstable during cycling. We also observed decomposition products from the binder material used in the cathode on the surface of the lithium anode. This new SEI layer has an increased resistance affecting the lithium deposition which is essential for battery operation.

Younesi, Reza; Hahlin, Maria; Roberts, Matthew; Edström, Kristina

2013-03-01

157

Frost flower formation on sea ice and lake ice  

NASA Astrophysics Data System (ADS)

Frost flowers are clusters of ice crystals found on freshly formed sea ice and occasionally on frozen lakes. They belong to a class of vapour-related phenomena that includes freezing fog, hoar frost and dew. It has hitherto been supposed that they form by condensation from a supersaturated atmosphere or from water wicked up through porous sea ice. Here we show that they can form on solid, pure ice sublimating into an unsaturated atmosphere. We derive a general regime diagram showing the atmospheric conditions under which the different vapour-related phenomena occur and confirm our predictions of frost-flower formation with a series of laboratory experiments. Our results can be used in climate models to predict occurrence of frost flowers, which significantly enhance albedo and provide the substrate for chemical production of ozone-depleting bromine monoxide, and in paleo-climate reconstructions by relating observations of sea-salt aerosols in ice cores to atmospheric conditions.

Style, Robert W.; Worster, M. Grae

2009-06-01

158

Frost rings in trees as records of major volcanic eruptions  

Microsoft Academic Search

New data about climatically-effective volcanic eruptions during the past several thousand years may be contained in frost-damage zones in the annual rings of trees. There is good agreement in the timing of frost events and recent eruptions, and the damage can be plausibly linked to climatic effects of stratospheric aerosol veils on hemispheric and global scales. The cataclysmic proto-historic eruption

V. C. Lamarche Jr.; Katherine K. Hirschboeck

1984-01-01

159

The potential importance of frost flowers, recycling on snow, and open leads for Ozone Depletion Events  

NASA Astrophysics Data System (ADS)

We present model studies with the one-dimensional model MISTRA to investigate the potential role of frost flowers, recycling on snow, and open leads in the depletion of tropospheric ozone in the Arctic spring. In our model, we assumed frost flower aerosols to be the major source of bromine. We show that a major ozone depletion event can be satisfactorily reproduced only if the recycling on snow of deposited bromine into gas phase bromine is assumed. In the model, this cycling is more efficient than the bromine explosion process and maintains sufficiently high levels of bromine to deplete ozone down to few nmol mol-1 within four days. We assessed the influence of different surface combinations (open lead/frost flowers) on the chemistry in the model. Results showed noticeable modifications affecting the composition of aerosols and the deposition velocities. A model run with a series of coupled frost flower fields and open leads, separated by large areas of snow, showed results comparable with field observations. In addition, we studied the effects of modified temperature of either the frost flower field or the ambient airmass. A warmer frost flower field increases the relative humidity and the aerosol deposition rate. The deposition/re-emission process gains in importance, inducing more reactive bromine in the gas phase, and a stronger ozone depletion. A decrease of 1 K in airmass temperature shows in our model that the aerosol uptake capacities of all gas phase species substantially increases, leading to enhanced uptake of acids from the gas phase. Consequently, the so-called bromine explosion accelerated and O3 mixing ratios decreased. In our model representation, variations in wind speed affected the aerosol source function and influenced the amount of bromine in the atmosphere and thus the ozone depletion strength. Recent studies have suggested the important role of the precipitation of calcium carbonate (CaCO3) out of the brine layer for the possible acidification of the liquid phase by acid uptake. Our investigation showed that this precipitation is a crucial process for the timing of the bromine explosion in aerosols. Nevertheless, model runs with either 50% precipitation or complete precipitation displayed a relatively weak difference in ozone mixing ratios after four simulated days. By considering conditions typical for "Arctic Haze" pollution events at the start of the run we obtained a low pH in frost flower aerosols due to a greater mixing ratio of SO2, and a strong recycling efficiency via large aerosol number concentration. The aerosol acidification during a haze event most likely intensifies the ozone depletion strength and occurrence. The comparison between our modeled deposition on snow and sampled snow at Barrow (Alaska) shows that approximately 75% of deposited bromine may be re-emitted into the gas phase as Br2/BrCl. Among several non-halogen fluxes from the snow, model simulations showed that only HONO affects the chemistry. Finally, we investigated the release of Br2 potentially produced by heterogeneous reactions directly on frost flowers. In this case, we obtained unrealistic results of aerosol compositions and deposition rates on snow compared to observations in the Arctic.

Piot, M.; von Glasow, R.

2007-04-01

160

The potential importance of frost flowers, recycling on snow, and open leads for ozone depletion events  

NASA Astrophysics Data System (ADS)

We present model studies with the one-dimensional model MISTRA to investigate the potential role of frost flowers, recycling on snow, and open leads in the depletion of tropospheric ozone in the Arctic spring. In our model, we assumed frost flower aerosols to be the major source of bromine. We show that a major ozone depletion event can be satisfactorily reproduced only if the recycling on snow of deposited bromine into gas phase bromine is assumed. In the model, this cycling is more efficient than the bromine explosion process and maintains sufficiently high levels of bromine to deplete ozone down to few nmol mol-1 within four days. We assessed the influence of different surface combinations (open lead/frost flowers) on the chemistry in the model. Results showed noticeable modifications affecting the composition of aerosols and the deposition velocities. A model run with a series of coupled frost flower fields and open leads, separated by large areas of snow, showed results comparable with field observations. In addition, we studied the effects of modified temperature of either the frost flower field or the ambient airmass. A warmer frost flower field increases the relative humidity and the aerosol deposition rate. The deposition/re-emission process gains in importance, inducing more reactive bromine in the gas phase, and a stronger ozone depletion. A decrease of 1K in airmass temperature shows in our model that the aerosol uptake capacities of all gas phase species substantially increases, leading to enhanced uptake of acids from the gas phase. Consequently, the so-called bromine explosion accelerated and O3 mixing ratios decreased. In our model representation, variations in wind speed affected the aerosol source function and influenced the amount of bromine in the atmosphere and thus the ozone depletion strength. Recent studies have suggested the important role of the precipitation of calcium carbonate (CaCO3) out of the brine layer for the possible acidification of the liquid phase by acid uptake. Our investigation showed that this precipitation is a crucial process for the timing of the bromine explosion in aerosols. Nevertheless, model runs with either 50% precipitation or complete precipitation displayed a relatively weak difference in ozone mixing ratios after four simulated days. By considering conditions typical for "Arctic Haze" pollution events at the start of the run we obtained a low pH in frost flower aerosols due to a greater mixing ratio of SO2, and a strong recycling efficiency via large aerosol number concentration. The aerosol acidification during a haze event most likely intensifies the ozone depletion strength and occurrence. The comparison between our modeled deposition on snow and sampled snow at Barrow (Alaska) shows that approximately 75% of deposited bromine may be re-emitted into the gas phase as Br2/BrCl. Among several non-halogen fluxes from the snow, model simulations showed that only HONO affects the chemistry. Finally, we investigated the release of Br2 potentially produced by heterogeneous reactions directly on frost flowers. In this case, we obtained unrealistic results of aerosol compositions and deposition rates on snow compared to observations in the Arctic.

Piot, M.; von Glasow, R.

2008-05-01

161

Coagulation of particles in Saturn's rings - Measurements of the cohesive force of water frost  

NASA Technical Reports Server (NTRS)

Experimental data are presented on the sticking force of water ice particles which are indicative of the role that the cohesive properties of such particles could play in the dynamics of Saturn ring particles. Sticking forces are dependent on particle impact velocities; a 'Velcro' model is devised to describe the surface structure involved in sticking. The data indicate that below the critical impact velocity of about 0.03 cm/sec, particle cohesion always occurs. Due to the optical depth of micron-sized grains in the Saturn rings, particles are hypothesized to be coated with a layer of frost which will render cohesion an important ring-dynamics process.

Hatzes, A. P.; Bridges, F.; Lin, D. N. C.; Sachtjen, S.

1991-01-01

162

(abstract) A Polarimetric Model for Effects of Brine Infiltrated Snow Cover and Frost Flowers on Sea Ice Backscatter  

NASA Technical Reports Server (NTRS)

A polarimetric scattering model is developed to study effects of snow cover and frost flowers with brine infiltration on thin sea ice. Leads containing thin sea ice in the Artic icepack are important to heat exchange with the atmosphere and salt flux into the upper ocean. Surface characteristics of thin sea ice in leads are dominated by the formation of frost flowers with high salinity. In many cases, the thin sea ice layer is covered by snow, which wicks up brine from sea ice due to capillary force. Snow and frost flowers have a significant impact on polarimetric signatures of thin ice, which needs to be studied for accessing the retrieval of geophysical parameters such as ice thickness. Frost flowers or snow layer is modeled with a heterogeneous mixture consisting of randomly oriented ellipsoids and brine infiltration in an air background. Ice crystals are characterized with three different axial lengths to depict the nonspherical shape. Under the covering multispecies medium, the columinar sea-ice layer is an inhomogeneous anisotropic medium composed of ellipsoidal brine inclusions preferentially oriented in the vertical direction in an ice background. The underlying medium is homogeneous sea water. This configuration is described with layered inhomogeneous media containing multiple species of scatterers. The species are allowed to have different size, shape, and permittivity. The strong permittivity fluctuation theory is extended to account for the multispecies in the derivation of effective permittivities with distributions of scatterer orientations characterized by Eulerian rotation angles. Polarimetric backscattering coefficients are obtained consistently with the same physical description used in the effective permittivity calculation. The mulitspecies model allows the inclusion of high-permittivity species to study effects of brine infiltrated snow cover and frost flowers on thin ice. The results suggest that the frost cover with a rough interface significantly increases the backscatter from thin saline ice and the polarimetric signature becomes closer to the isotropic characteristics. The snow cover also modifies polarimetric signatures of thin sea ice depending on the snow mixture and the interface condition.

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

1995-01-01

163

Photoconductive WSe 2 thin films obtained by solid state reaction in the presence of a thin nickel layer  

Microsoft Academic Search

Photoconductive WSe2 thin films have been obtained by post-annealing treatments of W\\/Se\\/W\\/…W\\/Se\\/W\\/Se thin layers sequentially deposited onto a thin Ni layer. The samples were first annealed under argon flow in an open reactor at 1093 K for 30 min.If the films obtained were textured and crystallized in the 2H-WSe2 structure, they were partly oxidized and selenium deficient. The oxide was

N. Guettari; J. Ouerfelli; J. C. Bernède; A. Khelil; J. Pouzet; A. Conan

1998-01-01

164

Modeling and simulation study of the self-discharge in supercapacitors in presence of a blocking layer  

NASA Astrophysics Data System (ADS)

Supercapacitors are promising energy storage devices due to their high life cycle and high power density. However, supercapacitors also known as Electric Double Layer Capacitor (EDLCs) are affected by high leakage or self discharge. The leakage is mainly dominated by redox reactions at the electrode surface through which electrons cross the double layer. Experiments have shown that a very thin blocking layer coating on the electrodes improves the energy storage capability by reducing the leakage, but it reduces the specific capacitance. The detrimental effect of the blocking layer on the capacitance requires the study of the blocking layer thickness' impact on the performance of the supercapacitor. In this work we have developed a mathematical model to study such effects. The model is a combination of simple quantum mechanical and electrochemical phenomena that occur during the self-discharge process. Using the developed model, a computational method was applied to simulate the discharge profile and specific energy in devices with various thicknesses in the blocking layer. The simulation approach can be used to study supercapacitor performances for practical applications.

Tevi, Tete; Takshi, Arash

2015-01-01

165

On the Effective Thermal Conductivity of Frost Considering Mass Diffusion and Eddy Convection  

NASA Technical Reports Server (NTRS)

A physical model for the effective thermal conductivity of water frost is proposed for application to the full range of frost density. The proposed model builds on the Zehner-Schlunder one-dimensional formulation for porous media appropriate for solid-to-fluid thermal conductivity ratios less than about 1000. By superposing the effects of mass diffusion and eddy convection on stagnant conduction in the fluid, the total effective thermal conductivity of frost is shown to be satisfactorily described. It is shown that the effects of vapor diffusion and eddy convection on the frost conductivity are of the same order. The results also point out that idealization of the frost structure by cylindrical inclusions offers a better representation of the effective conductivity of frost as compared to spherical inclusions. Satisfactory agreement between the theory and the measurements for the effective thermal conductivity of frost is demonstrated for a wide range of frost density and frost temperature.

Kandula, Max

2010-01-01

166

Scaled experimental models show that the pres-ence of a viscous layer, such as salt, facilitates the  

E-print Network

(Withjack et al., 1989, 1990). In these three regions, the presence of subsurface evaporites facili- tated and identifying the small-scale structures within them, however, can be difficult. Typically, the evaporitic

167

Generation and development of small-amplitude disturbances in a laminar boundary layer in the presence of an acoustic field  

NASA Technical Reports Server (NTRS)

A low-turbulence subsonic wind tunnel was used to study the influence of acoustic disturbances on the development of small sinusoidal oscillations (Tollmien-Schlichting waves) which constitute the initial phase of turbulent transition. It is found that acoustic waves propagating opposite to the flow generate vibrations of the model (plate) in the flow. Neither the plate vibrations nor the acoustic field itself have any appreciable influence on the stability of the laminar boundary layer. The influence of an acoustic field on laminar boundary layer disturbances is limited to the generation of Tollmien-Schlichting waves at the leading-edge of the plate.

Kachanov, Y. S.; Kozlov, V. V.; Levchenko, V. Y.

1985-01-01

168

Free flight determination of boundary layer transition on small scale cones in the presence of surface ablation  

NASA Technical Reports Server (NTRS)

To assess the possibility of achieving extensive laminar flow on conical vehicles during hyperbolic entry, the Ames Research Center has had an ongoing program to study boundary-layer transition on ablating cones. Boundary layer transition results are presented from ballistic range experiments with models that ablated at dimensionless mass transfer rates comparable to those expected for full scale flight at speeds up to 17 km/sec. It was found possible to measure the surface recession and hence more accurately identify regions of laminar, transitional, and turbulent flow along generators of the recovered cones. Some preliminary results using this technique are presented.

Wilkins, M. E.; Chapman, G. T.

1972-01-01

169

Shoot regeneration seedlings from transverse thin cell layer explants excised from cotyledon, petiole, hypocotyl of [{Brassica juncea} L. Czern.] in the presence of CdCl$_2$  

Microsoft Academic Search

The present work describes a novel neoformation process of \\\\textit{Brassica juncea} (L.) Czern. seedlings from transverse thin cell layers in the presence of CdCl$_2$. In order to investigate the regeneration ability of this crop, the effect of CdCl$_2$ on shoot regeneration (frequency of regeneration and bud number per tTCL) was examined. The tTCL explants were excised from cotyledon, petiole and

Michel Aoun; Jean-Yves Cabon; Annick Hourmant

2008-01-01

170

Study of a frost-less heat pump  

SciTech Connect

Heat pumps, used as primary residential space conditioning systems in many temperate climates, have inherent requirements for defrosting of the outdoor evaporator coil during the winter heating season when frost forms. This paper describes a new concept and the results of the new technology that minimizes evaporator coil frosting to ambient temperatures as low as 33 F, and that reduces or eliminates the need for reverse cycle defrosting at many conditions. By strategically adding controlled heat to the liquid stored in the accumulator, the evaporator temperature is increased. Depending on the amount of heat added, an evaporator temperature increase of 7 F can be realized. This increased coil temperature acts to decrease frosting in the ambient temperature range that has high frosting propensity, 33 F to 41 F. Proof-of-concept experiments were performed in both a baseline configuration and with the new frost-less technology on an of-the-shelf two-ton residential heat pump. Results are shown for outdoor air temperatures from 33 F to 41 F with relative humidity kept at 80%.

Domitrovic, R.E.; Chen, F.C.; Mei, V.C.; Murphy, R.W.; Kilpatrick, J.K.; Richardson, J.O.

1999-07-01

171

General frost growth mechanism on solid substrates with different stiffness.  

PubMed

Preventing or delaying frost formation on surfaces is of significant importance in many aspects of our daily life. Despite many efforts and improvements recently achieved in the design of new icephobic materials and substrates, not all proposed solutions are universally applicable and frost formation still remains a problem in need of further flexible solutions. In this respect, we propose to take benefit from the tunable viscoelastic properties of soft polymer gel substrates, since they are known to strongly influence the dropwise condensation process of water, and to investigate condensation frosting on them. Using polymer gels with different stiffness and a hard substrate as a reference, we demonstrate their ability to delay frost formation compared to recent results reported in the literature on other solid substrates and in particular on superhydrophobic surfaces. By investigating the frost front propagation we singled out a general behavior of its dynamic evolution consisting of two processes presenting two different time scales. This general growth appears to be independent of experimental conditions as well as substrate stiffness. PMID:24456462

Petit, Julien; Bonaccurso, Elmar

2014-02-01

172

Experimental study of a turbulent boundary layer in presence of external manipulators of NACA 0009 profile in the transonic regime  

Microsoft Academic Search

An experimental study was conducted to determine the effectiveness of manipulators of external-type turbulence on the reduction of wall drag in a turbulent boundary layer in the transonic regime. The manipulators used, NACA 0009 thin profile type, have an aerodynamic behavior inappropriate for this type of application. Flow visualizations show that the flow on the manipulator is complex, with regions

Diane Poirier

1990-01-01

173

Frost-weathering on Mars - Experimental evidence for peroxide formation  

NASA Technical Reports Server (NTRS)

The weathering of silicates by frost is investigated in relation to the formation of surface peroxides to which Viking biology experiment results have been attributed. Samples of the minerals olivine and pyroxene were exposed to water vapor at -11 to -22 C and resultant gas evolution and pH were monitored. Experiments reveal the formation of an acidic oxidant upon interaction of the mineral and H2O frost at subfreezing temperatures, which chemical indicators have suggested to be chemisorbed hydrogen peroxide. A model for the formation of chemisorbed peroxide based on the chemical reduction of the mineral by surface frost is proposed, and it is predicted that the perioxide would decay at high temperatures to H2O and adsorbed O, consistent with the long-term storage and sterilization behavior of the soil oxidants observed in the Viking Gas Exchange and Labeled Release experiments.

Huguenin, R. L.; Miller, K. J.; Harwood, W. S.

1979-01-01

174

FROST - FREEDOM OPERATIONS SIMULATION TEST VERSION 1.0  

NASA Technical Reports Server (NTRS)

The Space Station Freedom Information System processes and transmits data between the space station and the station controllers and payload operators on the ground. Components of the system include flight hardware, communications satellites, software and ground facilities. FROST simulates operation of the SSF Information System, tracking every data packet from generation to destination for both uplinks and downlinks. This program collects various statistics concerning the SSF Information System operation and provides reports of these at user-specified intervals. Additionally, FROST has graphical display capability to enhance interpretation of these statistics. FROST models each of the components of the SSF Information System as an object, to which packets are generated, received, processed, transmitted, and/or dumped. The user must provide the information system design with specified parameters and inter-connections among objects. To aid this process, FROST supplies an example SSF Information System for simulation, but this example must be copied before it is changed and used for further simulation. Once specified, system architecture and parameters are put into the input file, named the Test Configuration Definition (TCD) file. Alternative system designs can then be simulated simply by editing the TCD file. Within this file the user can define new objects, alter object parameters, redefine paths, redefine generation rates and windows, and redefine object interconnections. At present, FROST does not model every feature of the SSF Information System, but it is capable of simulating many of the system's important functions. To generate data messages, which can come from any object, FROST defines "windows" to specify when, what kind, and how much of that data is generated. All messages are classified by priority as either (1)emergency (2)quick look (3)telemetry or (4)payload data. These messages are processed by all objects according to priority. That is, all priority 1 (emergency) messages are processed and transmitted before priority 2 messages, and so forth. FROST also allows for specification of "pipeline" or "direct" links. Pipeline links are used to broadcast at constant intervals, while direct links transmit messages only when packets are ready for transmission. FROST allows the user substantial flexibility to customize output for a simulation. Output consists of tables and graphs, as specified in the TCD file, to be generated at the specified interval. These tables may be generated at short intervals during the run to produce snapshots as simulation proceeds, or generated after the run to give a summary of the entire run. FROST is written in SIMSCRIPT II.5 (developed by CACI) for DEC VAX series computers running VMS. FROST was developed on a VAX 8700 and is intended to be run on large VAXes with at least 32Mb of memory. The main memory requirement for FROST is dependent on the number of processors used in the simulation and the event time. The standard distribution medium for this package is a 9-track 1600 BPI DEC VAX BACKUP Format Magnetic Tape. An executable is included on the tape in addition to the source code. FROST was developed in 1990 and is a copyrighted work with all copyright vested in NASA. DEC, VAX and VMS are registered trademarks of Digital Equipment Corporation. IBM PC is a trademark of International Business Machines. SIMSCRIPT II.5 is a trademark of CACI.

Deshpande, G. K.

1994-01-01

175

Design guide for frost-protected shallow foundations  

SciTech Connect

Frost-protected shallow foundations (FPSFs) offer a proven technology designed to substantially lower construction costs in colder climates, enhancing housing affordability for families in many parts of the United States. This document provides step-by-step procedures to assist building professionals in designing and laying a slab- on-grade FPSF. FPSFs save money over conventional designs by requiring less excavation to construct a frost-proof foundation. It is specially insulated along its perimeter to raise the temperature of the surrounding ground and decrease frost penetration, thus allowing for the construction of a substantially shallower foundation. The FPSF is considered standard practice for homes in Scandinavia, where 40 years of field testing has proven it to be economical to construct, durable, and energy efficient. HUD strongly encourages wide spread adoption of FPSF technology in the United States and its incorporation into major model building codes.

NONE

1994-10-01

176

Frost sensor for use in defrost controls for refrigeration  

DOEpatents

An apparatus and method for measuring the total thermal resistance to heat flow from the air to the evaporative cooler fins of a refrigeration system. The apparatus is a frost sensor that measures the reduction in heat flow due to the added thermal resistance of ice (reduced conduction) as well as the reduction in heat flow due to the blockage of airflow (reduced convection) from excessive ice formation. The sensor triggers a defrost cycle when needed, instead of on a timed interval. The invention is also a method for control of frost in a system that transfers heat from air to a refrigerant along a thermal path. The method involves measuring the thermal conductivity of the thermal path from the air to the refrigerant, recognizing a reduction in thermal conductivity due to the thermal insulation effect of the frost and due to the loss of airflow from excessive ice formation; and controlling the defrosting of the system.

French, Patrick D. (ADA Technologies, Inc. 8100 Shaffer Pkwy., Suite 130, Littleton, CO 80127-4107); Butz, James R. (ADA Technologies, Inc. 8100 Shaffer Pkwy., Suite 130, Littleton, CO 80127-4107); Veatch, Bradley D. (ADA Technologies, Inc. 8100 Shaffer Pkwy., Suite 130, Littleton, CO 80127-4107); O'Connor, Michael W. (ADA Technologies, Inc. 8100 Shaffer Pkwy., Suite 130, Littleton, CO 80127-4107)

2002-01-01

177

Far-infrared spectra of CO2 clathrate hydrate frosts  

NASA Technical Reports Server (NTRS)

As a product of our interest in remote sensing of planetary ices, frost samples of CO2 clathrate hydrate were grown by depositing water vapor on a cooled surface and pressurizing the resulting water frost with CO2 gas. At pressures above the dissociation pressure of the clathrate, the samples exhibit an absorption peak at 75 cm (sup -1). At pressures below the dissociation pressure, the peak disappears. Since the free CO2 molecule does not have rotational or vibrational absorption in this region, the absorption is attributed to a CO2 rattling mode within a clathrate cage.

Landry, J. C.; England, A. W.

1993-01-01

178

Correlation of Water Frost Porosity in Laminar Flow over Flat Surfaces  

NASA Technical Reports Server (NTRS)

A dimensionless correlation has been proposed for water frost porosity expressing its dependence on frost surface temperature and Reynolds number for laminar forced flow over a flat surface. The correlation is presented in terms of a dimensionless frost surface temperature scaled with the cold plate temperature, and the freezing temperature. The flow Reynolds number is scaled with reference to the critical Reynolds number for laminar-turbulent transition. The proposed correlation agrees satisfactorily with the simultaneous measurements of frost density and frost surface temperature covering a range of plate temperature, ambient air velocity, humidity, and temperature. It is revealed that the frost porosity depends primarily on the frost surface and the plate temperatures and the flow Reynolds number, and is only weakly dependent on the relative humidity. The results also point out the general character of frost porosity displaying a decrease with an increase in flow Reynolds number.

Kandula, Max

2011-01-01

179

A Case Study of Coinduction in Isabelle HOL \\Lambda Jacob Frost y  

E-print Network

A Case Study of Co­induction in Isabelle HOL \\Lambda Jacob Frost y Computer Laboratory University of Cambridge e­mail:Jacob.Frost@cl.cam.ac.uk August 1993 Abstract The consistency of the dynamic and static

Haddadi, Hamed

180

A frost formation model for cold isothermal walls and its validation for varying ambient conditions  

SciTech Connect

A general frost formation model was developed to calculate the frost weight and thickness on a cold isothermal surface subjected to varying environmental parameters. The restrictions of limited frost density and temperature ranges were essentially removed by development of a generalized correlation of the water frost thermal conductivity. The diffusion approach used by Brian et al. was extended to include the full range of frost density and temperatures and to include the water seepage phase of the frost growth. Careful attention was given to the heat and mass transfer coefficients for a given air flow regime and geometrical shape. The extended frost formation model was successful in predicting the frost growth for various published data.

Dietenberger, M.A.

1985-01-01

181

Seasonally active frost-dust avalanches on a north polar scarp of Mars captured by HiRISE  

USGS Publications Warehouse

North-polar temporal monitoring by the High Resolution Imaging Science Experiment (HiRISE) orbiting Mars has discovered new, dramatic examples that Mars1 CO2-dominated seasonal volatile cycle is not limited to quiet deposition and sublimation of frost. In early northern martian spring, 2008, HiRISE captured several cases of CO2 frost and dust cascading down a steep, polar scarp in discrete clouds. Analysis of morphology and process reveals these events to be similar to terrestrial powder avalanches, sluffs, and falls of loose, dry snow. Potential material sources and initiating mechanisms are discussed in the context of the Martian polar spring environment and of additional, active, aeolian processes observed on the plateau above the scarp. The scarp events are identified as a trigger for mass wasting of bright, fractured layers within the basal unit, and may indirectly influence the retreat rate of steep polar scarps in competing ways. Copyright 2008 by the American Geophysical Union.

Russell, P.; Thomas, N.; Byrne, S.; Herkenhoff, K.; Fishbaugh, K.; Bridges, N.; Okubo, C.; Milazzo, M.; Daubar, I.; Hansen, C.; McEwen, A.

2008-01-01

182

Measurement of frost characteristics on heat exchanger fins. Part 2: Data and analysis  

SciTech Connect

Part 1 of this paper described the frost growth test facility and instrumentation. In Part 2, results are presented for typical operating conditions with frost growth on heat exchanger fins. Typical data are presented for frost height distributions on fins, increase in pressure loss for airflow through a finned test section, frost mass accumulation on fins, and heat rate. Special attention is given to the uncertainty in each of these measurements and calculations.

Chen, H.; Thomas, L.; Besant, R.W.

1999-07-01

183

Winter frost resistance of leaves of some plants growing in Dunedin, New Zealand, in winter 1985  

Microsoft Academic Search

The frost resistance of leaves of eleven different species of plants was measured in late July and early August 1985 when winter hardening to frost would be expected to be near its maximum. The frost resistance of the native plants was generally low (-5°C to -8°C except for Hebe albicans (—10°Q), but similar to previous studies. The exotic species originated

Peter Bannister

1986-01-01

184

Microclimate factors influencing the frequency and duration of growth season frost for subalpine plants  

Microsoft Academic Search

The subalpine environment of the Medicine Bow Mountains, Wyoming (USA) is characterized by frost events throughout the summer. As a result, growing season length is difficult to define in terms of frost-free days. For example, such a definition would have limited the 1993 growing season for many plants to only 5 days. The frequency of summertime frost events appeared particularly

Dean N. Jordan; William K. Smith

1995-01-01

185

Evaluation of MM5 Simulations With HTSVS With and Without Inclusion of Soil-Frost Parameterization  

E-print Network

Evaluation of MM5 Simulations With HTSVS With and Without Inclusion of Soil-Frost Parameterization and seasonally frozen ground are important surface features in high- latitudes. Because of this, a soil-frost and observations of precipitation were used to evaluate the importance of the soil-frost parameterization

Moelders, Nicole

186

Lessons in the Conversation That We Are: Robert Frost's "Death of the Hired Man."  

ERIC Educational Resources Information Center

Looks at Robert Frost's "The Death of the Hired Man" as a "representative anecdote" for Frost's work, which, taken as a whole, shows readers how to lose themselves among the overlooked places and turnings, the topics and tropes, that make up Frost's rhetorical home, the place of everyday human talk and gossip. (TB)

Jost, Walter

1996-01-01

187

Biocomplexity associated with biogeochemical cycles in arctic frost-boil ecosystems  

E-print Network

i Biocomplexity associated with biogeochemical cycles in arctic frost-boil ecosystems Principal CYCLES IN ARCTIC FROST-BOIL ECOSYSTEMS A PROJECT SUMMARY The central goal of this project to changing climate. We focus on frost-boils because: (1) The processes that are involved in the self

Wagner, Diane

188

Climatic controls on frost cracking and implications for the evolution of bedrock landscapes  

E-print Network

Climatic controls on frost cracking and implications for the evolution of bedrock landscapes T. C, a process called segregation ice growth. The depth and intensity of frost cracking is primarily dependent meter of the rock mass and a maximum frost penetration of $4 m. In contrast, negative MAT areas have

Roering, Joshua J.

189

Formation of ice lenses and frost heave A. W. Rempel1  

E-print Network

Formation of ice lenses and frost heave A. W. Rempel1 Received 13 April 2006; revised 26 January.g., lenses) and frost heave. I account for the net effect of these microscopic interactions in a homogenized. Citation: Rempel, A. W. (2007), Formation of ice lenses and frost heave, J. Geophys. Res., 112, F02S21, doi

Rempel, Alan W.

190

THE ASYMPTOTIC GIANT BRANCH J. C. LATTANZIO AND C. A. FROST  

E-print Network

THE ASYMPTOTIC GIANT BRANCH J. C. LATTANZIO AND C. A. FROST Department of Mathematics, Monash. The reader is referred to Iben & Renzini (1983), Frost & Lattanzio (1996a) and Lattanzio et al.(1996 expands. This essentially extinguishes the H­shell, #12; 2 J. C. LATTANZIO AND C. A. FROST CO core He

Lattanzio, John

191

Minimal Spray Strategy for Frosted Apple Trees Nikki Rothwell, District Fruit IPM Educator  

E-print Network

1 Minimal Spray Strategy for Frosted Apple Trees Nikki Rothwell, District Fruit IPM Educator Amy morning frost of Saturday, May 6th , many apples in the northwest region were affected. Based on some, if they find their trees suffered a lot of frost damage, they may want to opt for a minimal management program

192

ICARUS 62, 344-347 (1985) Polar Frost Formation on Ganymede  

E-print Network

ICARUS 62, 344-347 (1985) NOTE Polar Frost Formation on Ganymede R. E. JOHNSON Department Received June 25, 1984: revised February 4, 1985 The suggested models of polar frost formation on Ganymede is proposed. 19s5 Academic Press, Inc. Introduction. The observation of a polar frost on Ganymede, which

Johnson, Robert E.

193

The effect of excess nitrogen and of insect defoliation on the frost hardiness of bark tissue  

E-print Network

Short note The effect of excess nitrogen and of insect defoliation on the frost hardiness of bark winter frost, causing severe bark necroses, and insect defoliation are two of the causal factors on the frost hardiness of the bark of adult oaks was tested. At several dates dur- ing winter, samples from

Boyer, Edmond

194

Multiple Randomised Reed-Frost Epidemics and Epidemics upon Random Graphs  

E-print Network

Multiple Randomised Reed-Frost Epidemics and Epidemics upon Random Graphs Peter Neal To appear;The Annals of Applied Probability MULTITYPE RANDOMISED REED-FROST EPIDEMICS AND EPIDEMICS UPON RANDOM exten- sion of the randomised Reed-Frost epidemic model. The main result is the derivation

Sidorov, Nikita

195

Susceptibility of provenances and families of Pinus maximinoi and Pinus tecunumanii to frost in South Africa  

E-print Network

Susceptibility of provenances and families of Pinus maximinoi and Pinus tecunumanii to frost the variation in survival as a measure of frost tolerance within these two species to determine whether it could Genetic diversity Á Frost susceptibility Á South Africa Á Pinus maximinoi Á Pinus tecunumanii R. G

196

9/7/2004 Penumadu, Prashant, and Frost. EM-2004 1 A VIRTUAL TRIAXIAL COMPRESSION  

E-print Network

9/7/2004 Penumadu, Prashant, and Frost. EM-2004 1 A VIRTUAL TRIAXIAL COMPRESSION TEST SIMULATOR, Knoxville, TN, USA David J. Frost: Department of Civil and Environmental Engineering, Georgia Institute. #12;9/7/2004 Penumadu, Prashant, and Frost. EM-2004 2 Presentation Outline Concept of Virtual

Prashant, Amit

197

Hybridization techniques and frost tolerance studies in intraspecific hybrids of Eucalyptus globulus Labill  

E-print Network

Hybridization techniques and frost tolerance studies in intraspecific hybrids of Eucalyptus. In intra- specific hybrids, seed characteristics and growth were evaluated in the field and frost tolerance seed type. Some of these seeds were planted in the field and evaluated for growth. Frost folerance

Paris-Sud XI, Université de

198

Historic climate change impacts on soil frost in the Mid-Western  

E-print Network

1 Historic climate change impacts on soil frost in the Mid-Western United States Tushar Sinha #12;2 Outline · Why do we care about soil frost? · Observations of climate change · Variable Infiltration Capacity (VIC) model · Model calibration · Results #12;3 Why do we care about soil frost ? · Soil

Cherkauer, Keith

199

Seasonal soil frost in response to future climate change in the  

E-print Network

1 Seasonal soil frost in response to future climate change in the Midwestern US Tushar Sinha, Keith #12;2 Outline · Why do we care about soil frost? · Climate change impacts · Variable Infiltration Capacity (VIC) model · Model calibration and evaluation · Results #12;3 Why do we care about soil frost

Cherkauer, Keith

200

Frost flower formation on sea ice and lake ice Robert W. Style1  

E-print Network

Frost flower formation on sea ice and lake ice Robert W. Style1 and M. Grae Worster1 Received 22 January 2009; revised 20 April 2009; accepted 6 May 2009; published 10 June 2009. [1] Frost flowers to a class of vapour-related phenomena that includes freezing fog, hoar frost and dew. It has hitherto been

Worster, M. Grae

201

A Basic Thermodynamic Derivation of the Maximum Overburden Pressure Generated in Frost Heave  

E-print Network

A Basic Thermodynamic Derivation of the Maximum Overburden Pressure Generated in Frost Heave be generated in frost heave. The method stems from the fact that useful work can, in principle, be extracted from the forces generated by an advancing solidification front via the frost heave mechanism. Using

Libbrecht, Kenneth G.

202

Plant responses of quinoa ( Chenopodium quinoa Willd.) to frost at various phenological stages  

Microsoft Academic Search

Frost is one of the principal limiting factors for agricultural production in the high Andean region. One of the most important grain crops in that region, quinoa (Chenopodium quinoa Willd.), is generally less affected by frost than most other crop species, but little is known about its specific mechanisms for frost resistance. This study was undertaken to help understand quinoa’s

S.-E. Jacobsen; C. Monteros; J. L. Christiansen; L. A. Bravo; L. J. Corcuera; A. Mujica

2005-01-01

203

Long term spatial and temporal trends in frost day indices in Kansas, USA  

Technology Transfer Automated Retrieval System (TEKTRAN)

Frost day indices such as number of frost days (nFDs), frost free days (nFFDs), last spring freeze (LSF), first fall freeze (FFF), and growing-season length (GSL), were calculated using daily minimum air temperature (Tmin) values from 23 centennial weather stations spread across Kansas during four t...

204

Laminar boundary layer flow of a nanofluid along a wedge in the presence of suction/injection  

NASA Astrophysics Data System (ADS)

The behavior of an incompressible laminar boundary layer flow over a wedge in a nanofluid with suction or injection has been investigated. The model used for the nanofluid integrates the effects of the Brownian motion and thermophoresis parameters. The governing partial differential equations of this problem, subjected to their boundary conditions, are solved by the Runge-Kutta-Gill technique with the shooting method for finding the skin friction and the rate of heat and mass transfer. The result are presented in the form of velocity, temperature, and volume fraction profiles for different values of the suction/injection parameter, Brownian motion parameter, thermophoresis parameter, pressure gradient parameter, Prandtl number, and Lewis number. The conclusion is drawn that these parameters significantly affect the temperature and volume fraction profiles, but their influence on the velocity profile is comparatively smaller.

Kasmani, R. Md.; Muhaimin, I.; Kandasamy, R.

2013-05-01

205

Salt Frost Deterioration in Concrete Pavement --Causes and Mitigation  

E-print Network

Salt Frost Deterioration in Concrete Pavement --Causes and Mitigation Zhichao Liu, Will Hansen and special effects such as surface tension and osmotic effect (salt solution). ·Below the nucleation the surface contains a salt solution, pore suction attracts surface liquid and additional ice growth may

206

Genetic Architecture of Winter Hardiness and Frost Tolerance in Triticale  

PubMed Central

Abiotic stress experienced by autumn-sown crops during winter is of great economic importance as it can have a severe negative impact on yield. In this study, we investigated the genetic architecture of winter hardiness and frost tolerance in triticale. To this end, we used a large mapping population of 647 DH lines phenotyped for both traits in combination with genome-wide marker data. Employing multiple-line cross QTL mapping, we identified nine main effect QTL for winter hardiness and frost tolerance of which six were overlapping between both traits. Three major QTL were identified on chromosomes 5A, 1B and 5R. In addition, an epistasis scan revealed the contribution of epistasis to the genetic architecture of winter hardiness and frost tolerance in triticale. Taken together, our results show that winter hardiness and frost tolerance are complex traits that can be improved by phenotypic selection, but also that genomic approaches hold potential for a knowledge-based improvement of these important traits in elite triticale germplasm. PMID:24927281

Liu, Wenxin; Maurer, Hans Peter; Li, Guoliang; Tucker, Matthew R.; Gowda, Manje; Weissmann, Elmar A.; Hahn, Volker; Würschum, Tobias

2014-01-01

207

Heritability of frost-seeded red clover establishment  

Technology Transfer Automated Retrieval System (TEKTRAN)

In the colder parts of the United States, in late winter after disappearance of snow cover, red clover (Trifolium pratense) is often broadcast seeded into forage legume-depleted grass pastures to increase pasture forage quality. This method of establishment is referred to as frost seeding. However...

208

Water frost and ice - The near-infrared spectral reflectance 0.65-2.5 microns. [observed on natural satellites and other solar system objects  

NASA Technical Reports Server (NTRS)

The spectral reflectance of water frost and frost on ice as a function of temperature and grain size is presented with 1-1/2% spectral resolution in the 0.65- to 2.5-micron wavelength region. The well-known 2.0-, 1.65-, and 1.5-micron solid water absorption bands are precisely defined along with the little studied 1.25-micron band and the previously unidentified (in reflectance) 1.04-, 0.90-, and 0.81-micron absorption bands. The 1.5-microns band complex is quantitatively analyzed using a nonlinear least squares algorithm to resolve the band into four Gaussian components as a function of grain size and temperature. It is found that the 1.65-micron component, which was thought to be a good temperature sensor, is highly grain-size dependent and poorly suited to temperature sensing. Another Gaussian component appears to show a dependence of width on grain size while being independent of temperature. The relative apparent band depths are different for frost layers on ice than for thick layers of frost and may explain the apparent band depths seen in many planetary reflectance spectra.

Clark, R. N.

1981-01-01

209

Frosty North Polar Layers  

NASA Technical Reports Server (NTRS)

MGS MOC Release No. MOC2-349, 3 May 2003

This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image is a springtime view of frost-covered layers revealed by an eroded scarp in the martian north polar cap. The layers are thought to consist of a mixture of dust, ice, and possibly sand. Some layers are known to be a source for dark sand that occurs in nearby dunes. During the summer, this surface would be considerably darker because most of the bright frost sublimes away during the spring season. The picture covers an area about 3 km (1.9 mi) wide near 85.2oN, 4.4oW. Sunlight illuminates the scene from the lower left.

2003-01-01

210

Frost heave susceptibility of saturated soil under constant rate of freezing  

SciTech Connect

Introduced are the results of experiments carried out to quantitatively obtain the frost heave pressure and displacement of soil subjected to artificial freezing or freezing around in-ground liquefied natural gas storage tanks. This experiment is conducted to evaluate the frost heave susceptibility of saturated soil under overconsolidation. In other words, this experiment was carried out to obtain the relation of the over-burden pressure and freezing rate to the frost heave ratio by observing the frost heave displacement and freezing time of specimens by freezing the specimens at a constant freezing rate under a constant overburden pressure, while letting water freely flow in and out of the system. Introduced are the procedures for frost heave test required to quantitatively obtain the frost heave displacement and pressure of soil. Furthermore, the relation between the frost heave susceptibility and physical properties of soil obtained by this test is reported.

Ryokai, K.; Iguro, M.; Yoneyama, K.

1982-01-01

211

Severe soil frost reduces losses of carbon and nitrogen from the forest floor during simulated snowmelt: A laboratory experiment  

E-print Network

Severe soil frost reduces losses of carbon and nitrogen from the forest floor during simulated in understanding the impacts of soil frost on carbon (C) and nitrogen (N) cycling, but the effects of soil frost to determine the effects of soil frost on C and N fluxes from forest floor soils during snowmelt. Soil cores

Templer, Pamela

212

STUDY OF FROST GROWTH ON HEAT EXCHANGERS USED AS OUTDOOR COILS IN AIR SOURCE HEAT PUMP SYSTEMS  

E-print Network

STUDY OF FROST GROWTH ON HEAT EXCHANGERS USED AS OUTDOOR COILS IN AIR SOURCE HEAT PUMP SYSTEMS OF FROST GROWTH ON HEAT EXCHANGERS USED AS OUTDOOR COILS IN AIR SOURCE HEAT PUMP SYSTEMS Dissertation of Frost Growth . . . . . . . . . . . . . . . . . . . . . 7 2.2 Frost Growth on Simple Geometries

213

An Experimental Investigation on Frost Control Using DC and AC Electric Fields on a Horizontal, Downward-Facing Plate  

Microsoft Academic Search

The effects of DC and AC electric fields on frost formation on a horizontal downward-facing flat plate was investigated in the present experimental study. Frost growth was influenced and controlled by electric fields generated by an insulated wire electrode. In order to quantify the effects of DC and AC electric fields on frost growth, both mass transfer and frost height

V. Tudor; M. M. Ohadi; F. H. R. França

2003-01-01

214

Mars south polar spring and summer behavior observed by TES: seasonal cap evolution controlled by frost grain size  

USGS Publications Warehouse

Thermal Emission Spectrometer (TES) observations of the recession phase of Mars' south polar cap are used to quantitatively map this recession in both thermal and visual appearance. Geographically nonuniform behavior interior to the cap is characterized by defining several small regions which exemplify the range of behavior. For most of the cap, while temperatures remain near the CO2 frost point, albedos slowly increase with the seasonal rise of the Sun, then drop rapidly as frost patches disappear over a period of ?20 days. A “Cryptic” region remains dark and mottled throughout its cold period. TES observations are compared with first-order theoretical spectra of solid CO2 frost with admixtures of dust and H2O. The TES spectra indicate that the Cryptic region has much larger grained solid CO2 than the rest of the cap and that the solid CO2 here may be in the form of a slab. The Mountains of Mitchel remain cold and bright well after other areas at comparable latitude, apparently as a result of unusually small size of the CO2 frost grains; we found little evidence for a significant presence of H2O. Although CO2 grain size may be the major difference between these regions, incorporated dust is also required to match the observations; a self-cleaning process carries away the smaller dust grains. Comparisons with Viking observations indicate little difference in the seasonal cycle 12 Martian years later. The observed radiation balance indicates CO2 sublimation budgets of up to 1250 kg m?2. Regional atmospheric dust is common; localized dust clouds are seen near the edge of the cap prior to the onset of a regional dust storm and interior to the cap during the storm.

Kieffer, Hugh H.; Titus, Timothy N.; Mullins, Kevin F.; Christensen, Philip R.

2000-01-01

215

Layers  

NASA Astrophysics Data System (ADS)

The temperature-dependent photoresponse characteristics of MnAl2S4 layers have been investigated, for the first time, by use of photocurrent (PC) spectroscopy. Three peaks were observed at all temperatures. The electronic origin of these peaks was associated with band-to-band transitions from the valence-band states ?4( z), ?5( x), and ?5( y) to the conduction-band state ?1( s). On the basis of the relationship between PC-peak energy and temperature, the optical band gap could be well expressed by the expression E g( T) = E g(0) - 2.80 × 10-4 T 2/(287 + T), where E g(0) was estimated to be 3.7920 eV, 3.7955 eV, and 3.8354 eV for the valence-band states ?4( z), ?5( x), and ?5( y), respectively. Results from PC spectroscopy revealed the crystal-field and spin-orbit splitting were 3.5 meV and 39.9 meV. The gradual decrease of PC intensity with decreasing temperature can be explained on the basis of trapping centers associated with native defects in the MnAl2S4 layers. Plots of log J ph, the PC current density, against 1/ T, revealed a dominant trap level in the high-temperature region. By comparing PC and the Hall effect results, we confirmed that this trap level is a shallow donor 18.9 meV below the conduction band.

Hong, K. J.; Jeong, T. S.; Youn, C. J.

2014-09-01

216

H2O frost point detection on Mars  

NASA Technical Reports Server (NTRS)

The Viking Mars landers contain meteorological instrumentation to measure wind, temperature, and pressure but not atmospheric water content. The landings occurred during local summer, and it was observed that the nocturnal temperature decrease at sensor height (1.6 m) did not exhibit a uniform behavior at either site. It was expected that the rate of decrease would gradually slow, leveling off near sunrise. Instead, a leveling occurred several hours earlier. Temperature subsequently began a more rapid decrease which slowed by sunrise. This suggested that the temperature sensors may be detecting the frost point of water vapor. Analysis of alternative hypotheses demonstrates that none of these are viable candidates. The frost point interpretation is consistent with other lander and orbiter observations, with terrestrial experience, and with modeling of Mars' atmospheric behavior. It thus appears that the meteorology experiment can help provide a basis toward understanding the distribution and dynamics of Martian water vapor.

Ryan, J. A.; Sharman, R. D.

1981-01-01

217

Large quasi-circular features beneath frost on Triton  

NASA Technical Reports Server (NTRS)

Specially processed Voyager 2 images of Neptune's largest moon, Triton, reveal three large quasi-circular features ranging in diameter from 280 to 935 km within Triton's equatorial region. The largest of these features contains a central irregularly shaped area of comparatively low albedo about 380 km in diameter, surrounded by crudely concentric annuli of higher albedo materials. None of the features exhibit significant topographic expression, and all appear to be primarily albedo markings. The features are located within a broad equatorial band of anomalously transparent frost that renders them nearly invisible at the large phase angles (alpha greater than 90 deg) at which Voyager obtained its highest resolution coverage of Triton. The features can be discerned at smaller phase angles (alpha = 66 deg) at which the frost only partially masks underlying albedo contrasts. The origin of the features is uncertain but may have involved regional cryovolcanic activity.

Helfenstein, Paul; Veverka, Joseph; Mccarthy, Derek; Lee, Pascal; Hillier, John

1992-01-01

218

Chemical frost weathering of olivine: Experimental study and implications  

NASA Technical Reports Server (NTRS)

New experimental results are reported on the frost weathering of olivine. After first weathering, a decrease in Fe sup 2(+)M(2) absorption bands were noted. This decrease is related to the protonation of O(+) in the mineral. It is contented that this reaction may result in the regolith storage of 100 to 1000 m of H(sub 2) over the history of Mars.

Harris, S. L.; Huguenin, R. L.

1987-01-01

219

Climate Change Shifts Frost Seasons and Plant Growth  

NSDL National Science Digital Library

This month's issue of Ecology Letters adds new evidence to the effect of climate change on ecosystems. In a paper by Professor of Biology Dr. David Inouye of the University of Maryland, global climate change appears to influence early and late frost events, which in turn, "inhibit growth and possibly damage many plants." This news brief from ScienceDaily.com describes the recent finding and comments on its wider significance.

220

Morning Frost in Trench Dug by Phoenix, Sol 113  

NASA Technical Reports Server (NTRS)

This image from the Surface Stereo Imager on NASA's Phoenix Mars Lander shows morning frost inside the 'Snow White' trench dug by the lander, in addition to subsurface ice exposed by use of a rasp on the floor of the trench.

The camera took this image at about 9 a.m. local solar time during the 113th Martian day of the mission (Sept. 18, 2008). Bright material near and below the four-by-four set of rasp holes in the upper half of the image is water-ice exposed by rasping and scraping in the trench earlier the same morning. Other bright material especially around the edges of the trench, is frost. Earlier in the mission, when the sun stayed above the horizon all night, morning frost was not evident in the trench.

This image is presented in approximately true color.

The trench is 4 to 5 centimeters (about 2 inches) deep, about 23 centimeters (9 inches) wide.

Phoenix landed on a Martian arctic plain on May 25, 2008. The mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is led by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development was by Lockheed Martin Space Systems, Denver.

2008-01-01

221

High-resolution topography and albedo of the south polar layered deposits on Mars  

SciTech Connect

Using a new photoclinometric technique with high-resolution Mariner 9 images, maximum slopes of 10{degree}-20{degree} are found to occur on an exposure of layered deposits within the south polar residual cap of Mars. Stereophotogrammetry is used to constrain the photoclinometric solutions, which resolve layer thicknesses of 100-300 m. Albedo variations are correlated with slope, indicating that frost is present on level areas. There is evidence for temporal changes in frost distribution in the 7 days (4{degree} of L{sub 8}) between the two images used in this study. The magnitude of the slopes derived here and consideration of the stability of water ice at the surface of the layered deposits strongly suggest the presence of a competent weathering rind. The weathered surface may be composed of dark filamentary sublimation residue particles that protect the underlying ice from solar heating. This hypothesis is consistent with previous studies of the regional color and albedo of the layered deposits, which indicate that the deposits are slightly darker and less red than the bright dust that mantles much of the south polar region. Furthermore, the proposed weathering mechanism provides a plausible source of dark, saltating material for the Martian polar dune fields.

Herkenhoff, K.E.; Murray, B.C. (California Institute of Technology, Pasadena (USA))

1990-08-30

222

SO2 frost - UV-visible reflectivity and Io surface coverage  

NASA Technical Reports Server (NTRS)

The reflectance spectrum in the range 0.24-0.85 microns of SO2 frost is measured in light of the discovery of SO2 gas in the atmosphere of Io and the possible discovery of the frost on its surface. Frost deposits up to 1.5 mm thick were grown in vacuum at 130 K and bi-directional reflectance spectra were obtained. Typical SO2 frost is found to exhibit very low reflectivity (2-5%) at 0.30 microns, rising steeply at 0.32 microns to attain a maximum reflectivity (75-80%) at 4.0 microns and uniformly high reflectivity throughout the visible and near infrared. Comparison with the full disk spectrum of Io reveals that no more than 20% of the surface can be covered with optically thick SO2 frost. Combinations of surface materials including SO2 frost which can produce the observed spectrum are indicated.

Nash, D. B.; Fanale, F. P.; Nelson, R. M.

1980-01-01

223

[Research on quality changes in ginseng stems and leaves before and after frost].  

PubMed

The present study is to investigate the quality changes of ginseng stems and leaves before and after frost. The contents changes of ginsenoside, free amino acid, and total phenolic compounds, as well as DPPH radical scavenging effect before and after frost were measured. The content of 9 ginsenoside monomer in ginseng stems was decreased except for Rg, and Re after frost, but in ginseng leaves was all decreased. The total content of amino acids was decreased in ginseng stems after frost, while increased in ginseng leaves. The content of phenolic compounds in ginseng stems and leaves were both decreased after frost while the ability of DPPH radical scavenging was improved. The factor of frost has great impact on the quality of ginseng stems and leaves. PMID:25509298

Zhao, Yan; Ma, Shuang; Cai, En-Bo; Liu, Shuang-Li; Yang, He; Zhang, Lian-Xue; Wang, Shi-Jie

2014-08-01

224

Ice/frost/debris assessment for space shuttle Mission STS-32 (61-C)  

NASA Technical Reports Server (NTRS)

An Ice/Frost/Debris assessment was conducted for Space Shuttle Mission STS-32 (61-C). This assessment begins with debris inspections of the flight elements and launch facilities before and after launch. Ice/Frost formations are calculated during cryogenic loading of the external tank followed by an on-pad assessment of the Shuttle vehicle and pad at T-3 hours in the countdown. High speed films are reviewed after launch to identify Ice/Frost/Debris sources and investigate potential vehicle damage. The Ice/Frost/Debris conditions and their effects on the Space Shuttle are documented.

Stevenson, Charles G.; Katnik, Gregory N.; Speece, Robert F.

1986-01-01

225

Experimental assessment on the frost sensitivity during leaf development of juvenile Fagus sylvatica L.  

NASA Astrophysics Data System (ADS)

Late frost events in spring shape species distribution as well as reduce productivity. Till now, it is still not clear if future warming will lead to more frequent / stronger / more harmful frost damages in forestry and agriculture or not. Since the variability of extremes is increasing it seems that the risk of late frost damages in many regions may not decrease, even if the mean air temperature in general is increasing. A late frost event is only harmful if plants have initiated their leaf / flower development. Closed buds are usually very frost tolerant. However, once leaves develop after mild and warm spring periods, the new tissue is especially sensitive to freezing temperatures. Therefore not only the date of the last frost but also the weather history of the late winter / early spring determines if a frost event might result in frost damage or not. Tissue sensitivity to frost varies among species, but even within species there might be differences in frost tolerance during the different stages in leaf development. We set up an experiment to identify the frost risk in connection with the developmental stage of the leaves of juvenile beech. In order to vary the timing of frost events, we placed 1-year old potted beech trees 7times overnight in a climate chamber, in which the air temperature was cooled down to - 3° for five hours. For each tree the phenological stages were observed before and after the frost, the percent of damage was estimated after two days; additionally phenology of the damaged plants was observed weekly to document the recovery of their damage till May 23, 2013. Only about 30% of the plants were damaged. In general it can be stated if damage occurred it was a severe damage, only very few plants sustained little damage. We observed dependence on the date of the freezing event, rather than on specific phenological phases - the later the frost was applied the more plants were damaged. Damaged plants recovered relatively rapidly from the frost damage; three to six weeks after the event most of the damage plants were foliated equally to non-damaged plants. Only a few plants did not recover at all from the frost event.

Estrella, Nicole; Menzel, Annette

2014-05-01

226

Laboratory Evaluation of the Effect of HNO3 Uptake on Frost Point Hygrometer Measurement of Water Vapor under UT/LS Conditions  

NASA Astrophysics Data System (ADS)

Chilled mirror hygrometers (CMH) are widely used to measure water vapor in the troposphere and lower stratosphere from balloon-borne sondes. Systematic discrepancies among in situ water vapor instruments have been observed at low water vapor mixing ratios (< 5 ppm) in the upper troposphere and lower stratosphere (UT/LS). Understanding the source of the measurement discrepancies is important for a more accurate and reliable determination of water vapor abundance in this region. We have conducted a laboratory study to investigate the potential interference of gas-phase nitric acid (HNO3) with the measurement of frost point temperature, and consequently the water vapor mixing ratio, determined by CMH under conditions representative of operation in the UT/LS. No detectable interference in the measured frost point temperature was found for HNO3 mixing ratios of up to 2 ppb for exposure times up to 150 minutes. HNO3 was observed to co-condense on the mirror frost, with the adsorbed mass increasing linearly with time at constant exposure levels. Over the duration of a typical balloon sonde ascent (90-120 min), the maximum accumulated HNO3 amounts were comparable to monolayer coverage of the geometric mirror surface area, which likely corresponds to small fractional coverage of the actual frost layer surface area. This small amount of co-condensed HNO3 is consistent with the observed lack of HNO3 interference in the frost point measurement because the CMH utilizes significant reductions (>10%) in surface reflectivity by the condensate for the determination of H2O.

Thornberry, T.; Gierczak, T.; Gao, R.; Voemel, H.; Watts, L.; Burkholder, J. B.; Fahey, D. W.

2010-12-01

227

Ice barriers promote supercooling and prevent frost injury in reproductive buds, flowers and fruits of alpine dwarf shrubs throughout the summer?  

PubMed Central

Over-wintering reproductive buds of many woody plants survive frost by supercooling. The bud tissues are isolated from acropetally advancing ice by the presence of ice barriers that restrict ice growth. Plants living in alpine environments also face the risk of ice formation in summer months. Little knowledge exists, how reproductive structures of woody alpine plants are protected from frost injury during episodic summer frosts. In order to address this question, frost resistance of three common dwarf shrubs, Calluna vulgaris, Empetrum hermaphroditum and Loiseleuria procumbens was measured and ice formation and propagation were monitored in twigs bearing reproductive shoots during various stages of reproductive development (bud, anthesis, and fruit) throughout the alpine summer. Results indicated that, in the investigated species, ice barriers were present at all reproductive stages, isolating the reproductive shoots from ice advancing from the subtending vegetative shoot. Additionally, in the reproductive stems ice nucleating agents that are active at warm, sub-zero temperatures, were absent. The ice barriers were 100% effective, with the exception of L. procumbens, where in 13% of the total observations, the ice barrier failed. The ice barriers were localized at the base of the pedicel, at the anatomical junction of the vegetative and reproductive shoot. There, structural aspects of the tissue impede or prevent ice from advancing from the frozen stem into the pedicel of the reproductive shoot. Under the experimental conditions used in this study, ice nucleation initially occurred in the stem of the vegetative shoot at species-specific mean temperatures in the range of ?4.7 to ?5.8 °C. Reproductive shoots, however, remained supercooled and ice free down to a range of ?7.2 to ?18.2 °C or even below ?22 °C, the lowest temperature applied in the study. This level of supercooling is sufficient to prevent freezing of reproductive structures at the lowest air temperature occurring at the altitude of the upper distribution boundary of the natural habitat of the investigated species which is between ?8 and ?10 °C in summer. Frost resistance assays indicated that reproductive shoots are much less frost resistant than vegetative stems, and in contrast to vegetative shoots, are not ice tolerant. Supercooling of reproductive shoots in alpine, woody plant species is an effective mechanism that protects developing offspring from potential frost damage resulting from episodic summer freezing events. PMID:25284910

Kuprian, Edith; Briceño, Verónica F.; Wagner, Johanna; Neuner, Gilbert

2014-01-01

228

Nowcasting in the FROST-2014 Sochi Olympic project  

NASA Astrophysics Data System (ADS)

FROST (Forecast and Research: the Olympic Sochi Testbed) 2014 is a WMO WWRP international project aimed at development, implementation, and demonstration of capabilities of short-range numerical weather prediction and nowcasting technologies for mountainous terrain in winter season. Sharp weather contrasts and high spatial and temporal variability are typical for the region of the Sochi-2014 Olympics. Steep mountainous terrain and an intricate mixture of maritime sub-tropical and Alpine environments make weather forecasting in this region extremely challenging. Goals of the FROST-2014 project: • To develop a comprehensive information resource of Alpine winter weather observations; • To improve and exploit: o Nowcasting systems of high impact weather phenomena (precipitation type and intensity, snow levels, visibility, wind speed, direction and gusts) in complex terrain; o High-resolution deterministic and ensemble mesoscale forecasts in winter complex terrain environment; • To improve the understanding of physics of high impact weather phenomena in the region; • To deliver forecasts (Nowcasts) to Olympic weather forecasters and decision makers and assess benefits of forecast improvement. 46 Automatic Meteorological Stations (AMS) were installed in the Olympic region by Roshydromet, by owners of sport venues and by the Megafon corporation, provider of mobile communication services. The time resolution of AMS observations does not exceed 10 minutes. For a subset of the stations it is even equal to 1 min. Data flow from the new dual polarization Doppler weather radar WRM200 in Sochi was organized at the end of 2012. Temperature/humidity and wind profilers and two Micro Rain Radars (MRR) will supplement the network. Nowcasting potential of NWP models participating in the project (COSMO, GEM, WRF, AROME, HARMONIE) is to be assessed for direct and post-processed (e.g. Kalman filter, 1-D model, MOS) model forecasts. Besides the meso-scale models, the specialized nowcasting systems are expected to be used in the project - ABOM, CARDS, INCA, INTW, STEPS, MeteoExpert. FROST-2014 is intended as an 'end-to-end' project. Its products will be used by local forecasters for meteorological support of the Olympics and preceding test sport events. The project is open for new interested participants. Additional information is available at http://frost2014.meteoinfo.ru.

Bica, Benedikt; Wang, Yong; Joe, Paul; Isaac, George; Kiktev, Dmitry; Bocharnikov, Nikolai

2013-04-01

229

Nature and origin of layered deposits of the Martian polar regions  

NASA Technical Reports Server (NTRS)

Layered deposits in the Martian polar regions are interpreted as accumulations of dust derived from atmospheric suspensions. Depressed and eroded terrains of the equatorial region are considered to be the principal sources of dust. A depositional model based on polar precipitation of dust predicts the formation of a vast, dome-shaped, featureless plateau underlain by layered deposits and occupying most of the area of annual frost cover. The rates of accumulation of dust and water ice in the polar regions have been estimated on the basis of atmospheric conditions in the present era. The analysis indicates an accumulation time of about 500 x 1 million years for the layered deposits and the presence of significant quantities of water ice in the deposits beneath the perennial cap.

Cutts, J. A.

1973-01-01

230

Frost resistance of reproductive tissues during various stages of development in high mountain plants.  

PubMed

Frost resistance of reproductive vs aboveground vegetative structures was determined for six common European high alpine plant species that can be exposed to frosts throughout their whole reproductive cycle. Freezing tests were carried out in the bud, anthesis and fruit stage. Stigma and style, ovary, placenta, ovule, flower stalk/peduncle and, in Ranunculus glacialis, the receptacle were separately investigated. In all species, the vegetative organs tolerated on an average 2-5 K lower freezing temperatures than the most frost-susceptible reproductive structures that differed in their frost resistance. In almost all species, stigma, style and the flower stalk/peduncle were the most frost-susceptible reproductive structures. Initial frost damage (LT??) to the most susceptible reproductive structure usually occurred between -2 and -4°C independent of the reproductive stage. The median LT?? across species for stigma and style ranged between -3.4 and -3.7°C and matched the mean ice nucleation temperature (-3.7 ± 1.4°C). In R. glacialis, the flower stalk was the most frost-susceptible structure (-5.4°C), and was in contrast to the other species ice-tolerant. The ovule and the placenta were usually the most frost-resistant structures. During reproductive development, frost resistance (LT??) of single reproductive structures mostly showed no significant change. However, significant increases or decreases were also observed (2.1 ± 1.2 K). Reproductive tissues of nival species generally tolerated lower temperatures than species occurring in the alpine zone. The low frost resistance of reproductive structures before, during and shortly after anthesis increases the probability of frost damage and thus, may restrict successful sexual plant reproduction with increasing altitude. PMID:22420836

Neuner, Gilbert; Erler, Agnes; Ladinig, Ursula; Hacker, Jürgen; Wagner, Johanna

2013-01-01

231

Frost characteristics and heat transfer on a flat plate under freezer operating conditions: Part 1, Experimentation and correlations  

SciTech Connect

An experimental investigation of frost growth on a flat, cold surface supplied by subfreezing, turbulent, humid, parallel flow of air is presented. The operating conditions are typical of many commercial freezers. A test loop was constructed to perform the tests, and the frost height, frost mass concentration, and cold surface heat flux were measured using specially designed and calibrated instrumentation. Twenty tests were done for steady operating conditions, each starting with no initial frost accumulation, and were run for two to six hours giving 480 data samples. Measured results show that the frost characteristics differ significantly with frost growth data taken previously for room temperature airflow. Depending on the temperature of the cold plate and the relative humidity of the subfreezing supply air, the frost could appear to be either smooth or rough. Smooth frost, which occurred at warmer plate temperatures and lower supply air relative humidities, gave rise to frost growth that was much thinner and denser than that for the rough, thick, low-density frost. Frost growth characteristics are correlated as a function of five independent variables (time, distance from the leading edge, cold plate temperature ratio, humidity ratio, and Reynolds number). These correlations are presented separately for the full data set, the rough frost data, and the smooth frost data.

Mao, Y.; Besant, R.W.; Chen, H.

1999-07-01

232

Polar Dunes In Summer Exhibit Frost Patches, Wind Streaks  

NASA Technical Reports Server (NTRS)

Mars Global Surveyor passes over the north polar region of the red planet twelve times each day, offering many opportunities to observe how the polar cap frosts and dunes are changing as the days goby. Right now it is summer in the north. This picture, taken the second week of April 1999, shows darks and dunes and remnant patches of bright frost left over from the winter that ended in July 1998. Dark streaks indicate recent movement of sand. The picture covers an area only 1.4 kilometers (0.9 miles)across and is illuminated from the upper right.

Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.

1999-01-01

233

Dew and frost chemistry at a midcontinent site, United States  

SciTech Connect

Little national effort is being devoted to appraising the importance of dew in the research on acid rain and atmospheric pollutants. Because dew lingers directly on plants and is perhaps more concentrated than rain, especially during its evaporation, it may overshadow certain rain effects which work mainly through the soil. From July 1989 to July 1990 a total of 98 dew and 9 frost samples were collected at the University of Arkansas Agricultural Experiment Station, Fayetteville. The total water flux from dews and frosts per year was less than 2% of that from rains. Acid and nutrient fluxes were also much lower in dew. In the following series of ions the number in parentheses gives the percent of the yearly flux of the ion in dew compared to rain for the same time period: H[sup +] (0.06), Ca[sup 2+] (25), Mg[sup 2+] (11), K[sup +] (21), Na[sup +] (4), NH[sub 4][sup +] (10), Cl[sup [minus

Wagner, G.H.; Steele, K.F. (Univ. of Arkansas, Fayetteville (United States)); Peden, M.E. (Illinois State Water Survey, Champaign (United States))

1992-12-20

234

Robert Frost as Teacher. A Poet's Interpretation of the Teacher's Task.  

ERIC Educational Resources Information Center

Robert Frost's method of teaching is explained. He saw all education as self-education, not something a teacher can give a student. Frost believed freedom to be a necessity and his method gives the student much freedom while also placing a heavy burden of responsibility on him. (Article originally published in 1951.) (AF)

Larson, Mildred

1979-01-01

235

Heat and mass transfer in frost and ice, packed beds, and environmental discharges  

SciTech Connect

This volume covers issues related to heat and mass transfer in frost and ice packed beds, and environmental discharges. Topics include: measurements of the effects of frost on heat exchanger performance, a study of steam zone behavior in porous media, heat and mass transfer by natural convection, and a review of selected programs for atmospheric dispersion.

Arimilli, R.V. (Tennessee Univ., Knoxville, TN (United States)); Beasley, D.E. (Clemson University (US)); Sengupta, S.; Sherif, S.A. (Miami Univ., Coral Gables, FL (United States)); Watts, R.G. (Tulane Univ., New Orleans, LA (United States))

1990-01-01

236

In Live Interaction, Does Familiarity Promote Attraction or Contempt? Reply to Norton, Frost, and Ariely (2011)  

E-print Network

of the traditional literature) and Norton et al.'s, we sought to move researchers toward precisely the kindREPLY In Live Interaction, Does Familiarity Promote Attraction or Contempt? Reply to Norton, Frost and refute each of Norton, Frost, and Ariely's (2011) specific objections to the conclusion that, ceteris

Reber, Paul J.

237

The Antarctic First Regional Observing Study of the Troposphere (FROST) Project  

Microsoft Academic Search

An account is given of the Antarctic First Regional Observing Study of the Troposphere (FROST) project, which has been organized by the Physics and Chemistry of the Atmosphere Group of the Scientific Committee on Antarctic Research. The goals of FROST are to study the meteorology of the Antarctic, to determine the strengths and weaknesses of operational analyses and forecasts over

John Turner; Steven Colwell; Steven Leonard; David Bromwich; Stephen Dixon; Hugh Hutchinson; Kieran Jacka; Lawrie Marsh; Stephen Pendlebury; Tim Gibson; Terry Hart; Günther Heinemann; Michael Lieder; Henry Phillpot; Mike Pook; Ian Simmonds

1996-01-01

238

Computations on frost damage to Scots pine under climatic warming in boreal conditions  

SciTech Connect

To investigate the risk of frost damage to Scots pine (Pinus sylvestris L.) in northern regions under climatic warming, a submodel for such damage to trees was included in a forest ecosystem model of the gap type. An annual growth multiplier describing the effects of frost was calculated with the help of simulated daily frost hardiness and daily minimum temperature. The annual growth multiplier was used in the main ecosystem model when simulating the development of a tree stand using a time step of one year. Simulations of the growth and development of Scots pine stands in southern Finland (61{degrees} N) under an elevating temperature indicated that climatic warming could increase the risk of frost damage due to premature onset of growth during warm spells in the late winter and early spring. Risk of frost damage implies uncertainty in yield expectations from boreal forest ecosystems in the event of climatic warming. 38 refs., 9 figs., 4 tabs.

Kellomaeki, S.; Haenninen, H.; Kolstroem, M. [Univ. of Joensuu (Finland)

1995-02-01

239

Activating the Microscale Edge Effect in a Hierarchical Surface for Frosting Suppression and Defrosting Promotion  

PubMed Central

Despite extensive progress, current icephobic materials are limited by the breakdown of their icephobicity in the condensation frosting environment. In particular, the frost formation over the entire surface is inevitable as a result of undesired inter-droplet freezing wave propagation initiated by the sample edges. Moreover, the frost formation directly results in an increased frost adhesion, posing severe challenges for the subsequent defrosting process. Here, we report a hierarchical surface which allows for interdroplet freezing wave propagation suppression and efficient frost removal. The enhanced performances are mainly owing to the activation of the microscale edge effect in the hierarchical surface, which increases the energy barrier for ice bridging as well as engendering the liquid lubrication during the defrosting process. We believe the concept of harnessing the surface morphology to achieve superior performances in two opposite phase transition processes might shed new light on the development of novel materials for various applications. PMID:23981909

Chen, Xuemei; Ma, Ruiyuan; Zhou, Hongbo; Zhou, Xiaofeng; Che, Lufeng; Yao, Shuhuai; Wang, Zuankai

2013-01-01

240

Numerical and experimental investigation on frosting of energy-recovery ventilator  

NASA Astrophysics Data System (ADS)

Frosting of energy-recovery ventilators results in two major problems: increase of pressure losses and reduction of heat transfer rates. Frost formation of heat and mass exchangers used in these ventilation systems is investigated both experimentally and numerically. A numerical model for the prediction of the thermal behavior of the exchanger is presented. The model is validated with experimental data and is then employed to conduct a parametric study. Results indicate that the absolute humidity is the prevailing parameter for characterizing the frosting phenomenon. A frost-mass-fraction chart is established in terms of the absolute humidity of the warm exhaust stream and of the temperature of the cold supply stream. The effect of time and mass flowrate is also evaluated. The transient three-dimensional model shows that the absolute humidity and the temperature of both air flows vary nonlinearly in the frosted zone.

Bilodeau, Stephane; Mercadier, Yves; Brousseau, Patrick

241

Managing Potato Biodiversity to Cope with Frost Risk in the High Andes: A Modeling Perspective  

PubMed Central

Austral summer frosts in the Andean highlands are ubiquitous throughout the crop cycle, causing yield losses. In spite of the existing warming trend, climate change models forecast high variability, including freezing temperatures. As the potato center of origin, the region has a rich biodiversity which includes a set of frost resistant genotypes. Four contrasting potato genotypes –representing genetic variability- were considered in the present study: two species of frost resistant native potatoes (the bitter Solanum juzepczukii, var. Luki, and the non-bitter Solanum ajanhuiri, var. Ajanhuiri) and two commercial frost susceptible genotypes (Solanum tuberosum ssp. tuberosum var. Alpha and Solanum tuberosum ssp. andigenum var. Gendarme). The objective of the study was to conduct a comparative growth analysis of four genotypes and modeling their agronomic response under frost events. It included assessing their performance under Andean contrasting agroecological conditions. Independent subsets of data from four field experiments were used to parameterize, calibrate and validate a potato growth model. The validated model was used to ascertain the importance of biodiversity, represented by the four genotypes tested, as constituents of germplasm mixtures in single plots used by local farmers, a coping strategy in the face of climate variability. Also scenarios with a frost routine incorporated in the model were constructed. Luki and Ajanhuiri were the most frost resistant varieties whereas Alpha was the most susceptible. Luki and Ajanhuiri, as monoculture, outperformed the yield obtained with the mixtures under severe frosts. These results highlight the role played by local frost tolerant varieties, and featured the management importance –e.g. clean seed, strategic watering- to attain the yields reported in our experiments. The mixtures of local and introduced potatoes can thus not only provide the products demanded by the markets but also reduce the impact of frosts and thus the vulnerability of the system to abiotic stressors. PMID:24497912

Condori, Bruno; Hijmans, Robert J.; Ledent, Jean Francois; Quiroz, Roberto

2014-01-01

242

Winter moisture content and frost-crack occurrence in oak trees (Quercus petraea Liebl. and Q. robur L.)  

E-print Network

Winter moisture content and frost-crack occurrence in oak trees (Quercus petraea Liebl. and Q Our research investigates the relations between the frost-crack occurrence in oaks and some physical that frost-cracks occur with a higher frequency in trees growing on soils with high winter moisture content

Paris-Sud XI, Université de

243

Potential gradients produced by pore-space heterogeneities: Application to isothermal frost damage and submarine hydrate anomalies  

E-print Network

Potential gradients produced by pore-space heterogeneities: Application to isothermal frost damage the supply of constituents through a fluid phase. With frost damage, the gradi- ents in chemical potential for constituent supply. We illustrate the consequences and character of isothermal frost damage using the results

Rempel, Alan W.

244

The effects of summer exposure to ozone on the frost hardiness after the vegetation period of Norway  

E-print Network

The effects of summer exposure to ozone on the frost hardiness after the vegetation period of membrane integrity is thought to be the major cause of frost injury (Levitt, 1980), there are good af- fected the frost hardening and deharden- ing of Norway spruce (Picea abies L. Karst) and Sitka

Boyer, Edmond

245

A frost "buzzsaw" mechanism for erosion of the eastern Southern Alps, New Zealand T.C. Hales a,  

E-print Network

A frost "buzzsaw" mechanism for erosion of the eastern Southern Alps, New Zealand T.C. Hales a, , J Available online 3 January 2009 Keywords: Southern Alps Periglacial processes Frost buzzsaw Scree of uplift and erosion across the Southern Alps. Here, we assess the efficacy of frost cracking

Roering, Joshua J.

246

Early Spring, Severe Frost Events, and Drought Induce Rapid Carbon Loss in High Elevation Meadows  

PubMed Central

By the end of the 20th century, the onset of spring in the Sierra Nevada mountain range of California has been occurring on average three weeks earlier than historic records. Superimposed on this trend is an increase in the presence of highly anomalous “extreme” years, where spring arrives either significantly late or early. The timing of the onset of continuous snowpack coupled to the date at which the snowmelt season is initiated play an important role in the development and sustainability of mountain ecosystems. In this study, we assess the impact of extreme winter precipitation variation on aboveground net primary productivity and soil respiration over three years (2011 to 2013). We found that the duration of snow cover, particularly the timing of the onset of a continuous snowpack and presence of early spring frost events contributed to a dramatic change in ecosystem processes. We found an average 100% increase in soil respiration in 2012 and 2103, compared to 2011, and an average 39% decline in aboveground net primary productivity observed over the same time period. The overall growing season length increased by 57 days in 2012 and 61 days in 2013. These results demonstrate the dependency of these keystone ecosystems on a stable climate and indicate that even small changes in climate can potentially alter their resiliency. PMID:25207640

Arnold, Chelsea; Ghezzehei, Teamrat A.; Berhe, Asmeret Asefaw

2014-01-01

247

Helicity Asymmetry in gamma p -> pi+ n with FROST  

SciTech Connect

The main objective of the FROST experiment at Jefferson Lab is the study of baryon resonances. The polarization observable E for the reaction gamma p to pi+n has been measured as part of this program. A circularly polarized tagged photon beam with energies from 0.35 to 2.35 GeV was incident on a longitudinally polarized frozen-spin butanol target. The final-state pions were detected with the CEBAF Large Acceptance Spectrometer. Preliminary polarization data agree fairly well with present SAID and MAID partial-wave analyses at low photon energies. In most of the covered energy range, however, significant deviations are observed. These discrepancies underline the crucial importance of polarization observables to further constrain these analyses.

Steffen Strauch

2012-04-01

248

A search for frosts in Comet Bowell /1980b/  

NASA Technical Reports Server (NTRS)

Infrared observations of Comet Bowell represent the first search for frost signatures in a comet beyond 2 AU from the sun. Broad- and narrowband photometry has been obtained as well as CVF spectrophotometry of this comet and there is no evidence for absorption features in the spectral area between 1.25 and 2.3 microns. Models of the coma have been generated which constrain the volatile content of the grains an; are in agreement with the observed albedo. The darkness of the coma particles at large heliocentric distances indicates a low albedo nucleus as well. Brightness variations during the observing period seem to indicate an active nucleus at 4.5 AU from the sun.

Campins, H.; Lebofsky, L. A.; Rieke, G. H.; Lebofsky, M. J.

1982-01-01

249

Helicity Asymmetry in gamma p -> pi+ n with FROST  

E-print Network

The main objective of the FROST experiment at Jefferson Lab is the study of baryon resonances. The polarization observable E for the reaction gamma p to pi+n has been measured as part of this program. A circularly polarized tagged photon beam with energies from 0.35 to 2.35 GeV was incident on a longitudinally polarized frozen-spin butanol target. The final-state pions were detected with the CEBAF Large Acceptance Spectrometer. Preliminary polarization data agree fairly well with present SAID and MAID partial-wave analyses at low photon energies. In most of the covered energy range, however, significant deviations are observed. These discrepancies underline the crucial importance of polarization observables to further constrain these analyses.

Steffen Strauch; for the CLAS Collaboration

2011-08-15

250

Seasonal frost effects on the dynamic behavior of a twenty-story office building  

USGS Publications Warehouse

Studies have shown that seasonal frost can significantly affect the seismic behavior of a bridge foundation system in cold regions. However, little information could be found regarding seasonal frost effects on the dynamic behavior of buildings. Based on the analysis of building vibration data recorded by a permanent strong-motion instrumentation system, the objective of this paper is to show that seasonal frost can impact the building dynamic behavior and the magnitude of impact may be different for different structures. Ambient noise and seismic data recorded on a twenty-story steel-frame building have been analyzed to examine the building dynamic characteristics in relationship to the seasonal frost and other variables including ground shaking intensity. Subsequently, Finite Element modeling of the foundation-soil system and the building superstructure was conducted to verify the seasonal frost effects. The Finite Element modeling was later extended to a reinforced-concrete (RC) type building assumed to exist at a similar site as the steel-frame building. Results show that the seasonal frost has great impact on the foundation stiffness in the horizontal direction and a clear influence on the building dynamic behavior. If other conditions remain the same, the effects of seasonal frost on structural dynamic behavior may be much more prominent for RC-type buildings than for steel-frame buildings. ?? 2007 Elsevier B.V. All rights reserved.

Yang, Z.; Dutta, U.; Xiong, F.; Biswas, N.; Benz, H.

2008-01-01

251

Measurement of frost characteristics on heat exchanger fins. Part 1: Test facility and instrumentation  

SciTech Connect

A special test facility was developed to characterize frost growing on heat exchanger fins where the cold surfaces and the air supply conditions were similar to those experienced in freezers, i.e., cold surface temperatures ranging from {minus}35 C to {minus}40 C, air supply temperatures from {minus}10 C to {minus}20 C, and 80% to 100% relative humidity (RH). This test facility included a test section with removable fins to measure the frost height and mass concentration. Frost height on heat exchanger fins was measured using a new automated laser scanning system to measure the height of frost and its distribution on selected fins. The increase in air pressure loss resulting from frost growth on the fins was measured directly in the test loop. The frost mass accumulation distribution was measured for each test using special pre-etched fins that could be easily subdivided and weighed. The total heat rate was measured using a heat flux meter. These frost-measuring instruments were calibrated and the uncertainty of each is stated.

Thomas, L.; Chen, H.; Besant, R.W.

1999-07-01

252

Habitat characteristics of adult frosted elfins (Callophrys irus) in sandplain communities of southeastern Massachusetts, USA  

USGS Publications Warehouse

Changes to land use and disturbance frequency threaten disturbance-dependent Lepidoptera within sandplain habitats of the northeastern United States. The frosted elfin (Callophrys irus) is a rare and declining monophagous butterfly that is found in xeric open habitats maintained by disturbance. We surveyed potential habitat for adult frosted elfins at four sites containing frosted elfin populations in southeastern Massachusetts, United States. Based on the survey data, we used kernel density estimation to establish separate adult frosted elfin density classes, and then used regression tree analysis to describe the relationship between density and habitat features. Adult frosted elfin density was greatest when the host plant, wild indigo (Baptisia tinctoria), density was >2.6 plants/m2 and tree canopy cover was <29%. Frosted elfin density was inversely related to tree cover and declined when the density of wild indigo was <2.6 plants/m2 and shrub cover was ???16%. Even small quantities of non-native shrub cover negatively affected elfin densities. This effect was more pronounced when native herbaceous cover was <36%. Our results indicate that management for frosted elfins should aim to increase both wild indigo density and native herbaceous cover and limit native tree and shrub cover in open sandplain habitats. Elimination of non-native shrub cover is also recommended because of the negative effects of even low non-native shrub cover on frosted elfin densities. The maintenance of patches of early successional sandplain habitat with the combination of low tree and shrub cover, high host plant densities, and the absence of non-native shrubs appears essential for frosted elfin persistence, but may also be beneficial for a number of other rare sandplain insects and plant species. ?? 2006 Elsevier Ltd. All rights reserved.

Albanese, G.; Vickery, P.D.; Sievert, P.R.

2007-01-01

253

Quasi-two-layer finite-volume scheme for modeling shallow water flows over an arbitrary bed in the presence of external force  

E-print Network

1 Quasi-two-layer finite-volume scheme for modeling shallow water flows over an arbitrary bed. G. Slavin). Finite-volume numerical method for study shallow water flows over an arbitrary bed of the initial three-dimensional Euler equations. We are solving the shallow-water equations for one layer

254

The genetic potential for key biogeochemical processes in Arctic frost flowers and young sea ice revealed by metagenomic analysis.  

PubMed

Newly formed sea ice is a vast and biogeochemically active environment. Recently, we reported an unusual microbial community dominated by members of the Rhizobiales in frost flowers at the surface of Arctic young sea ice based on the presence of 16S gene sequences related to these strains. Here, we use metagenomic analysis of two samples, from a field of frost flowers and the underlying young sea ice, to explore the metabolic potential of this surface ice community. The analysis links genes for key biogeochemical processes to the Rhizobiales, including dimethylsulfide uptake, betaine glycine turnover, and halocarbon production. Nodulation and nitrogen fixation genes characteristic of terrestrial root-nodulating Rhizobiales were generally lacking from these metagenomes. Non-Rhizobiales clades at the ice surface had genes that would enable additional biogeochemical processes, including mercury reduction and dimethylsulfoniopropionate catabolism. Although the ultimate source of the observed microbial community is not known, considerations of the possible role of eolian deposition or transport with particles entrained during ice formation favor a suspended particle source for this microbial community. PMID:24673287

Bowman, Jeff S; Berthiaume, Chris T; Armbrust, E Virginia; Deming, Jody W

2014-08-01

255

Ice/frost/debris assessment for space shuttle mission STS-27R, December 2, 1988  

NASA Technical Reports Server (NTRS)

An Ice/Frost/Debris assessment was conducted for Space Shuttle Mission STS-27R. Debris inspections of the flight elements and launch pad are performed before and after launch. Ice/frost conditions are assessed by the use of computer programs, nomographs, and infrared scanner data during cryogenic loading of the vehicle followed by an on-pad visual inspection. High speed photography is viewed after launch to identify ice/debris sources and evaluate potential vehicle damage. The Ice/Frost/Debris conditions of Mission STS-27R and their effect on the Space Shuttle Program are documented.

Katnik, Gregory N.; Higginbotham, Scott A.

1989-01-01

256

KSC ice/frost/debris assessment for space shuttle mission STS-29R  

NASA Technical Reports Server (NTRS)

An ice/frost/debris assessment was conducted for Space Shuttle Mission STS-29R. Debris inspections of the flight elements and launch pad are performed before and after launch. Ice/frost conditions on the external tank are assessed by the use of computer programs, nomographs, and infrared scanner data during cryogenic loading of the vehicle followed by an on-pad visual inspection. High speed photography is analyzed after launch to identify ice/debris sources and evaluate potential vehicle damage. The ice/frost/debris conditions of Mission STS-29R and their effect on the Space Shuttle Program are documented.

Stevenson, Charles G.; Katnik, Gregory N.; Higginbotham, Scott A.

1989-01-01

257

Stability of polar frosts in spherical bowl-shaped craters on the moon, Mercury, and Mars  

NASA Technical Reports Server (NTRS)

A model of spherical bowl-shaped craters is described and applied to the moon, Mercury, and Mars. The maximum temperature of permanently shadowed areas are calculated using estimates of the depth/diameter ratios of typical lunar bowl-shaped craters and assuming a saturated surface in which the craters are completely overlapping. For Mars, two cases are considered: water frost in radiative equilibrium and subliming CO2 frost in vapor equilibrium. Energy budgets and temperatures are used to determine whether a craterlike depression loses mass faster or slower than a flat horizontal surface. This reveals qualitatively whether the frost surface becomes rougher or smoother as it sublimes.

Ingersoll, Andrew P.; Svitek, Tomas; Murray, Bruce C.

1992-01-01

258

Backscattering from frost on icy satellites in the outer solar system  

NASA Technical Reports Server (NTRS)

Two extreme models are presented of how frost and ice might be intermixed on a typical satellite surface: areal and intimate mixing. Applying such models to selected representative satellite data, it is found that the frost component of the surfaces of these outer satellites must itself be backscattering, unlike its terrestrial counterpart. The difference may arise because frost particles can have much more complex internal textures under the low-temperature and low-gravity conditions of the outer satellites than is the case on earth.

Verbiscer, Anne; Helfenstein, Paul; Veverka, Joseph

1990-01-01

259

The geochemical composition of frost flowers in the Alaskan Arctic and their role in mercury deposition  

NASA Astrophysics Data System (ADS)

Frost flowers are small (centimeters long) intricate crystals that form on newly formed sea ice. They grow from a combination of water vapor deposition and wicking of brine upward from the sea ice surface. Frost flowers are generally two to three times the salinity of seawater and they have a depleted sulfate to sodium ratio that is believed to be caused by the precipitation of mirabilite during their growth. They are a link between the lower atmosphere and sea ice and thus may play a role in the physical and chemical processes that deposit mercury to the Arctic. Reactive halogen radicals oxidize gaseous elemental mercury to reactive gaseous mercury in the lower atmosphere of the Arctic. The resulting reactive gaseous mercury is deposited to snow and ice during spring time Atmospheric Mercury Deposition events (AMDEs). Since frost flowers are halogen rich they are implicated in AMDE chemistry. We collected frost flowers, brine, snow and seawater from the Arctic Ocean north of Barrow, Alaska during three field seasons. Most recently, we participated in the sea ice component of the Ocean-Atmosphere-Sea Ice-Snow (OASIS) campaign in Barrow in 2009. All of our frost flowers yield sulfate to sodium ratios of less than 0.15 which is roughly half that of seawater (0.24). Brine collected from the sea ice surface yields sulfate to sodium ratios close to seawater values. Over an 11 day period all major elements but sulfate decreased in the frost flowers. This suggests that: 1) vapor phase deposition of ice to frost flowers continues long after they initially form, and 2) mirabilite precipitation continues after initial flower growth. Stable oxygen isotope values of the frost flowers became increasingly lower over time with ?18O values evolving from roughly -3‰ to -10‰ over the 11 day period. This further suggests vapor phase deposition onto exposed frost flower surfaces is a continual process following initial flower growth. Brine yielded ?18O values ranging between -0.1‰ and +4‰ suggesting oxygen-18 is preferentially fractionated out of the sea ice crystal lattice more than oxygen-16. Dissolved organic carbon concentrations were below 15 mg/L for all brine and frost flower samples but DOC was detected in seawater (10-11 mg/L). Mercury concentrations in frost flowers range between 25 and 200 ng/L. Some frost flowers were less than eight hours old which suggests that mercury deposition chemistry occurs on the timescale of hours. This geochemical information will be presented in reference to arctic atmospheric chemical processes that promote AMDEs.

Douglas, T. A.; Sturm, M.; Blum, J. D.; Sherman, L. S.; Steffen, A.; Simpson, W. R.

2009-12-01

260

Frost-free greenhouse: design and operation considrations for commercial and community management  

SciTech Connect

The following design topics are discussed: a frost-free greenhouse from a kit greenhouse, solving the energy problem, the greenhouse envelope, frost-free thermal analysis, no-cost energy conservation measures, standard insulating materials and techniques, thermal mass, ventilation and cooling systems, heat retention blankets for night insulation, and warm-air destratification. The following operation topics are included: inside the frost-free greenhouse, cost consideration, vegetable crops, ornamental crops, cut flowers, environment and layout, solar specific horticulture, potted plants, pest assault, suppliers of predators and parasites, case studies, and bibliographies. (MHR)

Not Available

1982-03-01

261

Published by the Program of Viticulture and Enology. Department of Horticulture. Michigan State University. Factors Related to Spring Frost Damage: What Are the Options  

E-print Network

University. 2003. Factors Related to Spring Frost Damage: What Are the Options G. Stanley Howell Professor of Horticulture Program of Viticulture and Enology Michigan State University Summary. Spring frost. Prevention is the best weapon to keep frost concerns to a minimum. The most important time to consider frost

Isaacs, Rufus

262

Mariner 9 observations of the south polar cap of Mars - Evidence for residual CO2 frost  

NASA Technical Reports Server (NTRS)

The first spacecraft observations of the south residual polar cap of Mars were obtained by the Mariner 9 orbiter during the Martian southern summer season, 1971-1972. Analyses of Viking orbiter observations obtained 3 Mars years later have shown that residual carbon dioxide frost was present at the south polar cap in 1977. In this study, Mariner 9 infrared interferometer spectrometer spectra and television camera images are used in conjuction with multispectral thermal emission models to constrain the temperatures of dark bare ground and bright frost regions within the south residual cap. The results provide strong evidence that carbon dioxide frost was present throughout the summer season despite the fact that the residual frost deposits observed by Mariner 9 were less extensive than those observed by Viking.

Paige, D. A.; Herkenhoff, K. E.; Murray, B. C.

1990-01-01

263

Frost flowers growing in the Arctic ocean-atmosphere-sea ice-snow interface: 2. Mercury exchange between the atmosphere, snow, and frost flowers  

NASA Astrophysics Data System (ADS)

Frost flowers are ice crystals that grow on refreezing sea ice leads in Polar Regions by wicking brine from the sea ice surface and accumulating vapor phase condensate. These crystals contain high concentrations of mercury (Hg) and are believed to be a source of reactive halogens, but their role in Hg cycling and impact on the fate of Hg deposited during atmospheric mercury depletion events (AMDEs) are not well understood. We collected frost flowers growing on refreezing sea ice near Barrow, Alaska (U.S.A.) during an AMDE in March 2009 and measured Hg concentrations and Hg stable isotope ratios in these samples to determine the origin of Hg associated with the crystals. We observed decreasing ?199Hg values in the crystals as they grew from new wet frost flowers (mean ?199Hg = 0.77 ± 0.13‰, 1 s.d.) to older dry frost flowers (mean ?199Hg = 0.10 ± 0.05‰, 1 s.d.). Over the same time period, mean Hg concentrations in these samples increased from 131 ± 6 ng/L (1 s.d.) to 180 ± 28 ng/L (1 s.d.). Coupled with a previous study of Hg isotopic fractionation during AMDEs, these results suggest that Hg initially deposited to the local snowpack was subsequently reemitted during photochemical reduction reactions and ultimately accumulated on the frost flowers. As a result of this process, frost flowers may lead to enhanced local retention of Hg deposited during AMDEs and may increase Hg loading to the Arctic Ocean.

Sherman, Laura S.; Blum, Joel D.; Douglas, Thomas A.; Steffen, Alexandra

2012-07-01

264

The transfer of heat and mass to a vertical plate under frosting conditions  

E-print Network

THE TRAESFPIR OF HEAT . 'ND NASH 10 A VERTICAL PLATE UNDER FROSTING CONDITIONS A Thesis Louis Joseph Poth, Jr. Submitted to the Graduate School of the Agricultural and Nechanioal College of Texas in partial fulfili ment of the requirements... of the Husselt-Grashof correlation for heat transfer. coefficient of saturation temper ture and concen- tration gradient correlation, for small temper- ature difference. ooefficient of frost specific gravity-thermal oonductivity correlation. coefficient...

Poth, Louis Joseph

1960-01-01

265

A study of heat pump fin staged evaporators under frosting conditions  

E-print Network

A STUDY OF HEAT PUMP FIN STAGED EVAPORATORS UNDER FROSTING CONDITIONS A Dissertation by JIANXIN YANG Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of DOCTOR... OF PHILOSOPHY May 2003 Major Subject: Mechanical Engineering A STUDY OF HEAT PUMP FIN STAGED EVAPORATORS UNDER FROSTING CONDITIONS A Dissertation by JIANXIN YANG Submitted to Texas A&M University in partial fulfillment of the requirements for the degree...

Yang, Jianxin

2004-09-30

266

An exact solution of boundary layer flow over a moving surface embedded into a nanofluid in the presence of magnetic field and suction/injection  

NASA Astrophysics Data System (ADS)

The effects of magnetic field, suction/injection, nanoparticles type, and nanoparticle volume fraction on heat transfer characteristics and mechanical properties of a moving surface embedded into cooling medium consists of water with Cu, Ag or Al2O3 particles are studied. The governing boundary layer equations are transformed to ordinary differential equations containing, suction/injection parameter, magnetic parameter, nanoparticle and volume fraction. These equations are solved analytically. The velocity and temperature profiles within the boundary layer are plotted and discussed in details for various values of the different parameters.

Elbashbeshy, E. M. A.; Emam, T. G.; Abdel-wahed, M. S.

2014-01-01

267

Study of frost melting on a heat pump heat exchanger  

SciTech Connect

This experimental work was carried out to obtain basic information on frost melting on a heat exchanger used as a heat pump air conditioner. The heat exchanger working fluid used in this experiment was a 50 wt% propylene glycol aqueous solution. The flow amount G and the temperature T{sub b} of the working fluid were 0.1 {lt} G m{sup 3}/hour {lt} 0.2 and 10 {lt} T{sub b}0{degrees}C {lt} 34, respectively. A melting thermal efficiency {eta} is defined in this paper as the ratio of the net heat for melting to the heat supplied to the heat exchanger until the critical time for melting t{sub c}. {eta} strongly depends on t{sub c}, and t{sub c} is strongly affected by G and T{sub b}. In conclusion, it was found that the heat supplied to the heat exchanger can be utilized with a high {eta} when t{sub c} becomes small.

Sugawara, M.; Kirihoshi, C.; Fujita, T. (Dept. of Mechanical Engineering, Akita Univ. (JP)); Uemura, S.; Yajima, R. (Daikin Industries, Ltd. (JP))

1990-01-01

268

Frost features in soil thin sections as a tool for Holocene reconstruction: a study case from the Northern Apennines  

NASA Astrophysics Data System (ADS)

The study of Holocene paleosols can be difficult in many cases, since soil features are usually much less expressed than in older paleosols and the ability to detect single genetic phases is much impaired. Frost action, a key diagnostic feature in past climate reconstructions, is not exempt to this rule, and can sometimes remain undetected at the macroscopic scale. In such cases micromorphology can be one of great use, since it raises the resolution of our observations allowing us to identify some of the less visible features. The northern slope of Mt. Cusna (2121 m a.s.l.) in the Northern Apennines is characterized by the presence of a paleosurface formed since the end of the last glacial period. Four soil profiles related to a morphologically flat area inside the paleosurface (at around 1760 m a.s.l.) were described and sampled for bulk and micromorphological analyses. Field descriptions and bulk analyses indicated the presence of two main soil units. The upper unit showed the structure of a colluvial deposit interested by a weak pedogenesis. The lower unit was composed by a truncated paleosol with strong evidence of clay illuviation. At the top of the lower unit, a blackish organic horizon poor in coarse particles and without apparent structure was found. At the microscopic level the microstructure of this blackish horizon, composed by fine (40-80 ?m) rounded granules, was interested by a pattern of parallel-perpendicular planar voids, which can be interpreted as the result of frost action. Moreover, in one profile they were expressed enough to form a secondary angular blocky structure, and in another profile a series of vertical fissures a few millimeters wide was also found at the top of the blackish horizon. These features weren't identified in any of the other horizons of the four described profiles. The micromorphological characteristics of these buried organic levels, coupled with the paleoenvironmental context of the profiles, allowed to interpret these horizons as the results of an independent pedogenetic phase. In fact, in mountain environments accumulation of organic matter at the soil surface without significant development is a likely sign of a period of climatic recrudescence. The presence of frost features clearly confirms this hypothesis. The absence of frost features both in the deeper paleosol unit and in the colluvium above suggests two things: first, that this period can be viewed as a climatic recrudescence of the previous one, during which a temperate forest paleosol was formed. Second, that temperatures were probably also colder than present, which implies a successive warming. Radiocarbon dating from one of the profiles puts the formation of the blackish horizon, and thus the period of climatic recrudescence, somewhere between the boundary Middle-Late Holocene and the Little Ice Age. This is consistent with the Holocene climatic fluctuations attested for Northern Italy, which describe the Late Holocene as an unstable phase of colder periods.

Stefano Mariani, Guido; Compostella, Chiara; Trombino, Luca

2014-05-01

269

Intramolecular vibrational energy redistribution from a high frequency mode in the presence of an internal rotor: Classical thick-layer diffusion and quantum localization  

E-print Network

We study the effect of an internal rotor on the classical and quantum intramolecular vibrational energy redistribution (IVR) dynamics of a model system with three degrees of freedom. The system is based on a Hamiltonian proposed by Martens and Reinhardt (J. Chem. Phys. {\\bf 93}, 5621 (1990).) to study IVR in the excited electronic state of para-fluorotoluene. We explicitly construct the state space and show, confirming the mechanism proposed by Martens and Reinhardt, that an excited high frequency mode relaxes via diffusion along a thick layer of chaos created by the low frequency-rotor interactions. However, the corresponding quantum dynamics exhibits no appreciable relaxation of the high frequency mode. We attribute the quantum suppression of the classical thick-layer diffusion to the rotor selection rules and, possibly, dynamical localization effects.

Paranjothy Manikandan; Srihari Keshavamurthy

2007-07-31

270

RFLP mapping of the vernalization ( Vrn1 ) and frost resistance ( Fr1 ) genes on chromosome 5A of wheat  

Microsoft Academic Search

A population of single chromosome recombinant lines was developed from the cross between a frost-sensitive, vernalization-insensitive substitution line, ‘Chinese Spring’ (Triticum spelta 5A) and a frost-tolerant, vernalization-sensitive line, ‘Chinese Spring’ (‘Cheyenne’ 5A), and used to map the genes Vrn1 and Fr1 controlling vernalization requirement and frost tolerance, respectively, relative to RFLP markers located on this chromosome. The Vrn1 and Fr1

G. Galiba; S. A. Quarrie; J. Sutka; A. Morgounov; J. W. Snape

1995-01-01

271

1.8.2001 31.12.2004 SOIL-FROST AND SNOW METAMORPHISM SIMULATIONS FOR THE BALTEX-  

E-print Network

01 LD 0036 1.8.2001 ­ 31.12.2004 SOIL-FROST AND SNOW METAMORPHISM SIMULATIONS FOR THE BALTEX://www.gi.alaska.edu/~molders/deklim.htm; http://www.uni-koeln.de/math-nat-fak/geomet/eurad.html Key words: soil-frost, snow metamorphism, data assimilation, 4DVAR, water and energy fluxes, BALTEX 1. Summary Modules to consider soil-frost and snow

Moelders, Nicole

272

Structural Analysis of the Redesigned Ice/Frost Ramp Bracket  

NASA Technical Reports Server (NTRS)

This paper describes the interim structural analysis of a redesigned Ice/Frost Ramp bracket for the Space Shuttle External Tank (ET). The proposed redesigned bracket consists of mounts for attachment to the ET wall, supports for the electronic/instrument cables and propellant repressurization lines that run along the ET, an upper plate, a lower plate, and complex bolted connections. The eight nominal bolted connections are considered critical in the summarized structural analysis. Each bolted connection contains a bolt, a nut, four washers, and a non-metallic spacer and block that are designed for thermal insulation. A three-dimensional (3D) finite element model of the bracket is developed using solid 10-node tetrahedral elements. The loading provided by the ET Project is used in the analysis. Because of the complexities associated with accurately modeling the bolted connections in the bracket, the analysis is performed using a global/local analysis procedure. The finite element analysis of the bracket identifies one of the eight bolted connections as having high stress concentrations. A local area of the bracket surrounding this bolted connection is extracted from the global model and used as a local model. Within the local model, the various components of the bolted connection are refined, and contact is introduced along the appropriate interfaces determined by the analysts. The deformations from the global model are applied as boundary conditions to the local model. The results from the global/local analysis show that while the stresses in the bolts are well within yield, the spacers fail due to compression. The primary objective of the interim structural analysis is to show concept viability for static thermal testing. The proposed design concept would undergo continued design optimization to address the identified analytical assumptions and concept shortcomings, assuming successful thermal testing.

Phillips, D. R.; Dawicke, D. S.; Gentz, S. J.; Roberts, P. W.; Raju, I. S.

2007-01-01

273

TuBaFrost: European virtual tumor tissue banking.  

PubMed

TuBaFrost is a consortium responsible for the task to create a virtual European human frozen tumor tissue bank, composed of high quality frozen tumor tissue collections with corresponding accurate diagnosis stored in European cancer centers and universities, searchable on the Internet, providing rules for access and use and a code of conduct to comply with the various legal and ethical regulations in European countries. Such infrastructure would enlarge tissue availability and accessibility in large amounts of specified or even rare tumor samples. Design of an infrastructure for European residual tissue banking with the described characteristics, clear focus points emerge that can be broken down in dedicated subjects: (1) standardization and quality assurance (QA) to avoid inter-institute quality variation; (2) law and ethics enabling exchange of tissue samples possible between institutes in the different European countries, where law and ethics are characterized by a strong variability; (3) rules for access, with sufficient incentives for collectors; (4) central database application containing innovations on search and selection procedures; (5) support when needed with histology images; and (6) Internet access to search and upload, with in addition a solid website giving proper information on the procedures, intentions and activities not only to the scientific community, but also to the general public. One consortium decision, part of the incentives for collectors, had major impact on the infrastructure; custodianship over the tissues as well as the tissues stay with the collector institute. Resulting in specimens that are not given to an organization, taking decisions on participation of requests, but instead the local collected tissues stay very easy to access by the collector and allows autonomous negotiation between collector and requestor on cooperation, coauthorship in publication or compensation in costs. Thereby, improving availability of large amounts of high quality samples of a highly specified or rare tumor types and contact opportunities for cooperation with other institutes. PMID:17163156

Riegman, P H J; Oomen, M H A; Dinjens, W N M; Oosterhuis, J W; Lam, K H; Spatz, A; Ratcliffe, C; Knox, K; Mager, R; Kerr, D; Pezzella, F; Van Damme, B; Van De Vijver, M; Van Boven, H; Morente, M M; Alonso, S; Kerjaschki, D; Pammer, J; López-Guerrero, J A; Llombart-Bosch, A; Carbone, A; Gloghini, A; Teodorovic, I; Isabelle, M; Passioukov, A; Lejeune, S; Therasse, P; Van Veen, E B

2006-01-01

274

Effects of climate change on phenology, frost damage, and floral abundance of montane wildflowers.  

PubMed

The timing of life history traits is central to lifetime fitness and nowhere is this more evident or well studied as in the phenology of flowering in governing plant reproductive success. Recent changes in the timing of environmental events attributable to climate change, such as the date of snowmelt at high altitudes, which initiates the growing season, have had important repercussions for some common perennial herbaceous wildflower species. The phenology of flowering at the Rocky Mountain Biological Laboratory (Colorado, USA) is strongly influenced by date of snowmelt, which makes this site ideal for examining phenological responses to climate change. Flower buds of Delphinium barbeyi, Erigeron speciosus, and Helianthella quinquenervis are sensitive to frost, and the earlier beginning of the growing season in recent years has exposed them to more frequent mid-June frost kills. From 1992 to 1998, on average 36.1% of Helianthella buds were frosted, but for 1999-2006 the mean is 73.9%; in only one year since 1998 have plants escaped all frost damage. For all three of these perennial species, there is a significant relationship between the date of snowmelt and the abundance of flowering that summer. Greater snowpack results in later snowmelt, later beginning of the growing season, and less frost mortality of buds. Microhabitat differences in snow accumulation, snowmelt patterns, and cold air drainage during frost events can be significant; an elevation difference of only 12 m between two plots resulted in a temperature difference of almost 2 degrees C in 2006 and a difference of 37% in frost damage to buds. The loss of flowers and therefore seeds can reduce recruitment in these plant populations, and affect pollinators, herbivores, and seed predators that previously relied on them. Other plant species in this environment are similarly susceptible to frost damage so the negative effects for recruitment and for consumers dependent on flowers and seeds could be widespread. These findings point out the paradox of increased frost damage in the face of global warming, provide important insights into the adaptive significance of phenology, and have general implications for flowering plants throughout the region and anywhere climate change is having similar impacts. PMID:18409425

Inouye, David W

2008-02-01

275

Modeling the reflectance of CO2 frost with new optical constants: Application to Martian south polar cap spectra  

NASA Technical Reports Server (NTRS)

New measurements of the absorption coefficients of CO2 ice, in most of the spectral range 0.2 to 3.9 microns where absorption coefficients are below 1.5 per cm, have recently been made. Although these measurements are preliminary, they contain spectral detail not seen previously in the literature. Therefore, it is useful to combine these new data with older data from spectral regions of stronger absorption and reformulate models of the albedo or reflectance of CO2 frost. These models can then be adjusted in an attempt to match measurements of Martian polar deposits, such as the set of spectra returned by the IRS instrument on Mariner 7 (1969). The new absorption coefficients of CO2 ice were measured on several samples of 41-mm thickness at 150-155 K. A portion of the spectrum from 1.9 to 3.9 microns wavelength is shown in the form of imaginary coefficient of refraction ( = linear absorption x wavelength / 4 pi). The data above 3x10(exp -5) are obtained from, except for the absorption line at 3.32 micrometers, which is extrapolated in a way that is consistent with laboratory frost measurements, but the peak level is still highly uncertain. This new imagary coefficient, combined with the real coefficient, can be immediately applied to the models for hemispherical albedo, resulting in markedly different results from those in that study. The results for an infinite optical depth layer and solar incidence of 60 degrees are plotted for a range of mean particle radii from 0.03 to 3 mm.

Hansen, Gary B.; Martin, Terry Z.

1993-01-01

276

Future Bloom and Blossom Frost Risk for Malus domestica Considering Climate Model and Impact Model Uncertainties  

PubMed Central

The future bloom and risk of blossom frosts for Malus domestica were projected using regional climate realizations and phenological (?=?impact) models. As climate impact projections are susceptible to uncertainties of climate and impact models and model concatenation, the significant horizon of the climate impact signal was analyzed by applying 7 impact models, including two new developments, on 13 climate realizations of the IPCC emission scenario A1B. Advancement of phenophases and a decrease in blossom frost risk for Lower Saxony (Germany) for early and late ripeners was determined by six out of seven phenological models. Single model/single grid point time series of bloom showed significant trends by 2021–2050 compared to 1971–2000, whereas the joint signal of all climate and impact models did not stabilize until 2043. Regarding blossom frost risk, joint projection variability exceeded the projected signal. Thus, blossom frost risk cannot be stated to be lower by the end of the 21st century despite a negative trend. As a consequence it is however unlikely to increase. Uncertainty of temperature, blooming date and blossom frost risk projection reached a minimum at 2078–2087. The projected phenophases advanced by 5.5 d K?1, showing partial compensation of delayed fulfillment of the winter chill requirement and faster completion of the following forcing phase in spring. Finally, phenological model performance was improved by considering the length of day. PMID:24116022

Hoffmann, Holger; Rath, Thomas

2013-01-01

277

Will loss of snow cover during climatic warming expose New Zealand alpine plants to increased frost damage?  

PubMed

If snow cover in alpine environments were reduced through climatic warming, plants that are normally protected by snow-lie in winter would become exposed to greater extremes of temperature and solar radiation. We examined the annual course of frost resistance of species of native alpine plants from southern New Zealand that are normally buried in snowbanks over winter (Celmisia haastii and Celmisia prorepens) or in sheltered areas that may accumulate snow (Hebe odora) and other species, typical of more exposed areas, that are relatively snow-free (Celmisia viscosa, Poa colensoi, Dracophyllum muscoides). The frost resistance of these principal species was in accord with habitat: those from snowbanks or sheltered areas showed the least frost resistance, whereas species from exposed areas had greater frost resistance throughout the year. P. colensoi had the greatest frost resistance (-32.5 degrees C). All the principal species showed a rapid increase in frost resistance from summer to early winter (February-June) and maximum frost resistance in winter (July-August). The loss of resistance in late winter to early summer (August-December) was most rapid in P. colensoi and D. muscoides. Seasonal frost resistance of the principal species was more strongly related to daylength than to temperature, although all species except C. viscosa were significantly related to temperature when the influence of daylength was accounted for. Measurements of chlorophyll fluorescence indicated that photosynthetic efficiency of the principal species declined with increasing daylength. Levels of frost resistance of the six principal alpine plant species, and others measured during the growing season, were similar to those measured in tropical alpine areas and somewhat more resistant than those recorded in alpine areas of Europe. The potential for frost damage was greatest in spring. The current relationship of frost resistance with daylength is sufficient to prevent damage at any time of year. While warmer temperatures might lower frost resistance, they would also reduce the incidence of frosts, and the incidence of frost damage is unlikely to be altered. The relationship of frost resistance with daylength and temperature potentially provides a means of predicting the responses of alpine plants in response to global warming. PMID:15891822

Bannister, Peter; Maegli, Tanja; Dickinson, Katharine J M; Halloy, Stephan R P; Knight, Allison; Lord, Janice M; Mark, Alan F; Spencer, Katrina L

2005-06-01

278

Modified Ion-Acoustic Shock Waves and Double Layers in a Degenerate Electron-Positron-Ion Plasma in Presence of Heavy Negative Ions  

NASA Astrophysics Data System (ADS)

A general theory for nonlinear propagation of one dimensional modified ion-acoustic waves in an unmagnetized electron-positron-ion (e-p-i) degenerate plasma is investigated. This plasma system is assumed to contain relativistic electron and positron fluids, non-degenerate viscous positive ions, and negatively charged static heavy ions. The modified Burgers and Gardner equations have been derived by employing the reductive perturbation method and analyzed in order to identify the basic features (polarity, width, speed, etc.) of shock and double layer (DL) structures. It is observed that the basic features of these shock and DL structures obtained from this analysis are significantly different from those obtained from the analysis of standard Gardner or Burgers equations. The implications of these results in space and interstellar compact objects (viz. non-rotating white dwarfs, neutron stars, etc.) are also briefly mentioned.

Hossen, M. A.; Hossen, M. R.; Mamun, A. A.

2014-12-01

279

Reflectance spectra for sodium and potassium doped ammonia frosts - Implications for Io's surface  

NASA Technical Reports Server (NTRS)

This paper reports measurements of the reflection spectra of sodium- and potassium-doped ammonia frosts as a function of alkali metal concentration for the wavelength range 0.35-2.5 microns. The purpose of the measurements was to determine whether or not the reflection spectra for such a solid was compatible with the spectra albedo of Io. The data show that, with a sufficiently large alkali metal concentration, the reflection spectra of the doped ammonia frosts do not display the characteristic ammonia features at 2.0 and 2.25 micron. The high reflectance of the more concentrated samples and the character of the observed reflection spectrum make it difficult to rule out sodium-doped ammonia frost as a surface constituent on Io on the basis of existing data.

Rosen, M. D. A.; Pipkin, F. M.

1978-01-01

280

Frost Growth CFD Model of an Integrated Active Desiccant Rooftop Unit  

SciTech Connect

A frost growth model is incorporated into a Computational Fluid Dynamics (CFD) simulation of a heat pump by means of a user-defined function in FLUENT, a commercial CFD code. The transient model is applied to the outdoor section of an Integrated Active Desiccant Rooftop (IADR) unit in heating mode. IADR is a hybrid vapor compression and active desiccant unit capable of handling 100% outdoor air (dedicated outdoor air system) or as a total conditioning system, handling both outdoor air and space cooling or heating loads. The predicted increase in flow resistance and loss in heat transfer capacity due to frost build-up are compared to experimental pressure drop readings and thermal imaging. The purpose of this work is to develop a CFD model that is capable of predicting frost growth, an invaluable tool in evaluating the effectiveness of defrost-on-demand cycles.

Geoghegan, Patrick J [ORNL; Petrov, Andrei Y [ORNL; Vineyard, Edward Allan [ORNL; Zaltash, Abdolreza [ORNL; Linkous, Randall Lee [ORNL

2008-01-01

281

North Polar Surfaces of the Uranian Moons: Coated with CO2 Frost?  

NASA Astrophysics Data System (ADS)

We propose to investigate the near-surface composition of the Uranian moons Ariel, Umbriel, Titania, and Oberon by using the Infrared Array Camera (IRAC) onboard the Spitzer Space Telescope. Previous IRAC observations of these objects in Program 71 (2003 - 2005) indicate that the surfaces of their southern hemispheres are dominated by pure water ice (sub-observer latitudes 7 - 18 degree S). The observations we propose here are of these objects' now observable northern hemispheres (sub-observer latitudes 25 - 33 degree N). Unlike the Program 71 observations, which collected data near the end of southern summer when any seasonal CO2 frost would have migrated to the winter hemisphere, we are proposing to observe these moons at the beginning of northern summer when seasonal CO2 frost should still be present. Therefore, the 2015 - 2016 Cycle 11 opportunity window represents an ideal time frame to search for seasonal CO2 frost on these objects.

Cartwright, Richard; Emery, Joshua; Rivkin, Andy; Trilling, David; Pinilla-Alonso, Noemi

2014-12-01

282

Frost hardiness of mycorrhizal and non-mycorrhizal Scots pine under two fertilization treatments.  

PubMed

Survival and functioning of mycorrhizal associations at low temperatures are not known well. In an earlier study, ectomycorrhizas did not affect the frost hardiness of Scots pine (Pinus sylvestris L.) roots, but here we studied whether differential nutrient availability would change the result and additionally, alter frost hardiness aboveground. The aim in this experiment was to compare the frost hardiness of roots and needles of mycorrhizal (Hebeloma sp.) and non-mycorrhizal Scots pine seedlings raised using two fertilization treatments and two cold-hardening regimes. The fertilization treatments were low (LF) and high (HF) application of a complete nutrient solution. Three hundred mycorrhizal and non-mycorrhizal seedlings were cultivated in growth chambers in four blocks for 16 weeks. For the first 9 weeks, the seedlings grew in long-day and high-temperature (LDHT) with low fertilization and then they were raised for 3 weeks in LDHT with either low or high fertilization. After this, half of the plants in each treatment combination remained in LDHT, and half were transferred to short-day and low-temperature (SDLT) conditions to cold acclimatize. The frost hardiness of the roots and needles was assessed using controlled freezing tests followed by electrolyte leakage tests (REL). Mycorrhizal roots were slightly more frost hardy than non-mycorrhizal roots, but only in the growing-season conditions (LDHT) in low-nutrient treatment. In LDHT and LF, the frost hardiness of the non-mycorrhizal roots was about -9 °C, and that of the non-mycorrhizal HF roots and the mycorrhizal roots in both fertilization levels was about -11 °C. However, no difference was found in the roots within the SDLT regime, and in needles, there was no difference between mycorrhizal and fertilization treatments. The frost hardiness of needles increased by SDLT treatment, being -8.5 and -14.1 °C in LDHT and SDLT, respectively. The dry mass of roots, stems, and needles was lower in LF than in HF and lower in SDLT than in LDHT. Mycorrhizal treatment did not affect the dry mass or its allocation. Although the mycorrhizal roots were slightly more frost hardy in the growing-season conditions, this is not likely to have significance in the field. PMID:25404213

Korhonen, Anna; Lehto, Tarja; Repo, Tapani

2014-11-18

283

Io meteorology - How atmospheric pressure is controlled locally by volcanos and surface frosts  

NASA Technical Reports Server (NTRS)

The present modification of the Ingersoll et al. (1985) hydrodynamic model of the SO2 gas sublimation-driven flow from the day to the night side of Io includes the effects of nonuniform surface properties noted in observational studies. Calculations are conducted for atmospheric pressures, horizontal winds, sublimation rates, and condensation rates for such surface conditions as patchy and continuous frost cover, volcanic venting, surface temperature discontinuities, subsurface cold trapping, and the propagation of insolation into the frost. While pressure is found to follow local vapor pressure away from the plumes, it becomes higher inside them.

Ingersoll, Andrew P.

1989-01-01

284

Balloon borne Antarctic frost point measurements and their impact on polar stratospheric cloud theories  

NASA Technical Reports Server (NTRS)

Balloon-borne frost point measurements were performed over Antarctica during September-October 1987 as part of the NOZE II effort at McMurdo. The results show water mixing ratios on the order of 2 ppmv in the 20 km region, suggesting that models of the springtime Antarctic stratosphere should be based on approximately 2 ppmv water vapor. Evidence indicating that some PSCs form at temperatures higher than the frost point in the 15 to 20 km region is discussed. This supports the binary HNO3-H2O theory of PSC composition.

Rosen, James M.; Hofmann, D. J.; Carpenter, J. R.; Harder, J. W.; Oltsmans, S. J.

1988-01-01

285

Correlation between Cold- and Drought-Induced Frost Hardiness in Winter Wheat and Rye Varieties.  

PubMed

Exposure of six wheat (Triticum aestivum L.) and one rye (Secale cereale L.) cultivar to 40% relative humidity for 24 hours induced the same degree of freezing tolerance in seedling epicotyls as did cold conditioning for 4 weeks at 2 degrees C.Frost hardiness varietal relationships were the same in desiccation-stressed and cold-hardened seedlings. Drought stress could, therefore, be used as a rapid and simple method for inducing frost hardiness in seedling shoots in replacement of cold conditioning. PMID:16662170

Cloutier, Y; Siminovitch, D

1982-01-01

286

The influence of thermal inertia on temperatures and frost stability on Triton  

NASA Technical Reports Server (NTRS)

It is presently argued, in view of (1) a thermal inertia model for the surface of Triton which (like previous ones) predicts a monotonic recession of permanent N2 deposits toward the poles and very little seasonal N2 frost in the southern hemisphere, and (2) new spectroscopic evidence for nonvolatile CO2 on Triton's bright southern hemisphere, that much of that bright southern material is not N2. Such bright southern hemisphere volatiles may allow the formation of seasonal frosts, thereby helping to explain the observed spectroscopic changes of Triton during the last decade.

Spencer, John R.; Moore, Jeffrey M.

1992-01-01

287

A nano-frost array technique to prepare nanoporous PVDF membranes  

NASA Astrophysics Data System (ADS)

Frost, the solid deposition of water vapor from humid air, forms on the surface of a solid substrate when its temperature drops below the freezing point of water. In this study, we demonstrate how this natural phenomenon can be applied to develop novel nanoporous materials. The solvent annealing of polyvinylidene fluoride (PVDF) infiltrated into nanopores induced template-directed dewetting thus preparing nanoembossing films. Then, water nanodroplets formed on the cold polymer nanopatterned surfaces following the embossing patterns, similar to dew formation on the ground. Subsequently, the nanodroplets were frozen and then removed by freeze-drying. This nano-frost array technique produced nanoporous PVDF membranes with an average thickness of 250 (+/-48) nm. It was revealed that the nanopatterned surface formed by solvent annealing played an important role in achieving a nano-frost array with an adjustable size. Additionally, the freezing process led to significant changes of the PVDF crystallinity and polymorphism. Our results prove that the nano-frost array technique can be broadly used to design ordered nanoporous structures and provide new prospects in nanomaterial fields.Frost, the solid deposition of water vapor from humid air, forms on the surface of a solid substrate when its temperature drops below the freezing point of water. In this study, we demonstrate how this natural phenomenon can be applied to develop novel nanoporous materials. The solvent annealing of polyvinylidene fluoride (PVDF) infiltrated into nanopores induced template-directed dewetting thus preparing nanoembossing films. Then, water nanodroplets formed on the cold polymer nanopatterned surfaces following the embossing patterns, similar to dew formation on the ground. Subsequently, the nanodroplets were frozen and then removed by freeze-drying. This nano-frost array technique produced nanoporous PVDF membranes with an average thickness of 250 (+/-48) nm. It was revealed that the nanopatterned surface formed by solvent annealing played an important role in achieving a nano-frost array with an adjustable size. Additionally, the freezing process led to significant changes of the PVDF crystallinity and polymorphism. Our results prove that the nano-frost array technique can be broadly used to design ordered nanoporous structures and provide new prospects in nanomaterial fields. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr00951g

Lee, Min Kyung; Lee, Jonghwi

2014-07-01

288

Evidence of frost-cracking inferred from acoustic emissions in a high-alpine rock-wall  

E-print Network

Evidence of frost-cracking inferred from acoustic emissions in a high-alpine rock-wall D. Amitranoa within rock is known to be an important driver of near-surface frost weathering as well as of rock damage at the depth of several meters, which may play a crucial role for the slow preconditioning of rock fall

Paris-Sud XI, Université de

289

A red clover stand that was frost seeded into wheat. Using red clover as a cover crop in wheat  

E-print Network

better when frost seeded into well fertilized wheat fields. Benefits of red clover A red clover coverA red clover stand that was frost seeded into wheat. Using red clover as a cover crop in wheat Dan. Canadian-grown mammoth clover does not tolerate the increased shading and competition from well fertilized

290

Traffic Handling and Network Capacity in Multi-Service Networks Towela P.R. Nyirenda-Jere Victor S. Frost Nail Akar  

E-print Network

. Frost Nail Akar Information and Telecommunication Information and Telecommunication Electrical Bilkent University towela@ittc.ukans.edu frost@ittc.ukans.edu akar@ee.bilkent.edu.tr Abstract-- This paper

Kansas, University of

291

A three-dimensional model study on the production of BrO and Arctic boundary layer ozone depletion  

Microsoft Academic Search

A three-dimensional model (GEM-AQ\\/Arctic) was developed to study the chemistry and processes involved in the ozone depletion events (ODEs) in the Arctic boundary layer (ABL), which included a comprehensive mechanism of multiphase halogen chemistry in the ABL and our current understanding of the ODEs. Assuming that frost flower-derived aerosols were the primary halogen source, the areas potentially covered by frost

T. L. Zhao; S. L. Gong; J. W. Bottenheim; J. C. McConnell; R. Sander; L. Kaleschke; A. Richter; A. Kerkweg; K. Toyota; L. A. Barrie

2008-01-01

292

Study of frost growth on heat exchangers used as outdoor coils in air source heat pump systems  

NASA Astrophysics Data System (ADS)

Scope and method of study. During winter heating operation, the outdoor coil of a heat pump acts as an evaporator and when the ambient temperature is near freezing, the moisture in the atmospheric air freezes on the coil surface. The frost growth affects the air flow and also adds resistance to heat transfer thus reducing the capacity and the efficiency of the heat pump. An experimental facility is designed and built to test a small scale heat exchanger working in frosting conditions. Tests are carried out using small scale fin-tube and microchannel heat exchanger over a range of glycol inlet temperatures, air velocities and ambient air RH. A semi-empirical frost model based on a scaling approach is developed and applied to both fin-tube heat and microchannel heat exchangers. The model is developed to handle non-uniformities in both refrigerant and air side. The frost model is integrated with a segment-by-segment heat exchanger calculation algorithm and is validated against experimental data. Frost growth model is also incorporated in a quasi-steady state system simulation algorithm. Findings and conclusions. From the experimental study it was observed that the temperature of the surface and air RH affected the rate of frost growth significantly while the air velocity did not have a great influence. It is demonstrated that a dry heat transfer correlation can be used during frost growth period by correctly accounting for frost thickness in the hydraulic diameter calculations. Ignoring the phenomenon of air redistribution was found to result in errors in the range of 20% to 50% in predicted frost thickness. Frost thickness predicted by the frost model is within 5% of the measured values for most of the cases. Frost mass accumulation predicted by the simple model is higher than the measured values due to a uniform thickness assumption in the model. An improved frost model based on 1-D finite volume discretization is also presented which improved the frost mass prediction to within 13% of measured values. The system simulation is validated against experimental results and found to match reasonable well. The discrepancy between simulation and experiments were due to the effects of system transience in the initial stages.

K P, Sankaranarayanan

2011-12-01

293

Association of sugar content QTL and PQL with physiological traits relevant to frost damage resistance in pea under field and controlled conditions  

Microsoft Academic Search

To increase yield in pea (Pisum sativum L.), autumn sowing would be preferable. Hence, frost tolerance of pea became a major trait of interest for breeders. In order\\u000a to better understand the cold acclimation in pea, Champagne a frost tolerant line and Terese, a frost sensitive line, and\\u000a their recombinant inbred lines (RIL) were studied. RIL frost tolerance was evaluated

Estelle Dumont; Véronique Fontaine; Christophe Vuylsteker; Hélène Sellier; Sylvie Bodèle; Najia Voedts; Rosemonde Devaux; Marlène Frise; Komlan Avia; Jean-Louis Hilbert; Nasser Bahrman; Eric Hanocq; Isabelle Lejeune-Hénaut; Bruno Delbreil

2009-01-01

294

Fracture Mechanical Analysis of Frost Wedging in Ice Shelves as Break-Up Mechanism  

NASA Astrophysics Data System (ADS)

Disintegration events in ice shelves have been the subject of extensive investigations in the past years, however comprehensive explanations applicable to a majority of events are still missing. A popular assumption made by Scambos et al. (2000) [1] links disintegration events to a general thinning of the ice shelf in conjunction with growing melt-water ponds leading to hydro fractures. This explanation seems reasonable for break-up events that happened in Antarctic summers. Large parts of the Wilkins Ice Shelf, however broke-up in fall and winter periods. Therefore, the aim of the present study is to analyse the possibility of frost wedging of water filled surface crevasses in an ice shelf as a source of break-up events. Configurational forces are used to assess crack criticality. The simulations are performed on a 2-dimensional single crack with a mode-I type load, body forces and additional crack-face pressure due to freezing of the water. Depth-dependent density profiles are considered. The relevant parameters, Young's modulus, Poisson's ratio and external loading are obtained from literature, remote sensing data analysis and modelling of the ice dynamics. The investigation is performed using the finite element software COMSOL. The simulations show that in comparison to water filled crevasses without ice, thin layers of frozen water may lead to a decreasing criticality at the crack tip as long as the ice 'bridge' is allowed to take tensile loads. An increasing crack criticality can be seen for thicker layers of ice. The results are compared to findings from previous finite element analyses of dry and water filled cracks as presented in Plate et al. (2012) [2]. [1] Scambos, T., Hulbe, C., Fahnestock, M., & Bohlander, J. (2000). The link between climate warming and break-up of ice shelves in the Antarctic Peninsula. Journal of Glaciology, 46(154), 516-530. [2] Plate, C., Müller, R., Humbert, A., & Gross, D. (2012). Evaluation of the criticality of cracks in ice shelves using finite element simulations. The Cryosphere, 6(5), 973-984.

Plate, Carolin; Humbert, Angelika; Gross, Dietmar; Müller, Ralf

2013-04-01

295

A Conceptual Model of H2O/CO2 Frost Sublimation and Condensation Caused Albedo Change in Crater Interiors, Martian Seasonal Polar Cap Regions H. Xie1  

E-print Network

A Conceptual Model of H2O/CO2 Frost Sublimation and Condensation Caused Albedo Change in Crater at the seasonal polar cap regions, especially those associated with high-albedo deposits of frost and/or ice of ice and frost and detected first by Viking Orbiter/MGS [10]. [11] used Mars Orbiter Laser Altimetry

Texas at San Antonio, University of

296

THE EFFECT OF FROST/FREEZE EVENTS ON MOPANE TREES Prepared by Melissa Whitecross, Honours student, at the University of the Witwatersrand  

E-print Network

THE EFFECT OF FROST/FREEZE EVENTS ON MOPANE TREES Prepared by Melissa Whitecross, Honours student, at the University of the Witwatersrand There are many studies that suggest frost as a possible driver of savanna that Colophospermum mopane (Mopane Tree) is affected by frost/freeze events and this could be related to the unique

297

Published by Program of Viticulture and Enology. Department of Horticulture. Michigan State University. Estimating Functional Nodes Retained in Winter and/or Frost  

E-print Network

University. 2002. Estimating Functional Nodes Retained in Winter and/or Frost Damaged Vineyards. G. Stanley nodes retained at pruning. 1. There are 2-frost episodes in the spring after budburst. 2. After the last chance of frost has passed (usually around 1-7 June) and before shoot crowding has begun, counts were

Isaacs, Rufus

298

Frost resistance and biochemical changes during cold acclimation in different annual legumes  

Microsoft Academic Search

In Mediterranean areas of southern Europe growth of forages is seriously limited by the ability of each species to growth during cold winter. Therefore, the objective of this work was to prove the capacity for cold acclimation and frost resistance in four annual legumes native of Mediterranean region under laboratory conditions. Plants from subterranean clover (Trifolium subterraneum L. ssp. brachycalycinum

Marta Hekneby; M. Carmen Antolín; Manuel Sánchez-Díaz

2006-01-01

299

Frost fatigue and spring recovery of xylem vessels in three diffuse-porous trees in situ.  

PubMed

Frost has been shown to cause frost fatigue (reduced cavitation resistance) in branch segments in the lab. Here, we studied the change in cavitation resistance and percent loss of conductivity (PLC) from fall to spring over 2 consecutive years in three diffuse-porous species in situ. We used the cavitron technique to measure P25 , P50 and P90 (the xylem pressure causing a 25, 50 and 90% conductivity loss) and PLC and stained functioning vessels. Cavitation resistance was reduced by 64-87% (in terms of P50 ), depending on the species and year. P25 was impacted the most and P90 the least, changing the vulnerability curves from s- to r-shaped over the winter in all three species. The branches suffered an almost complete loss of conductivity, but frost fatigue did not necessarily occur concurrently with increases in PLC. In two species, there was a trade-off between conduit size and vulnerability. Spring recovery occurred by growth of new vessels, and in two species by partial refilling of embolized conduits. Although newly grown and functioning conduits appeared more vulnerable to cavitation than year-old vessels, cavitation resistance generally improved in spring, suggesting other mechanisms for partial frost fatigue repair. PMID:24117494

Christensen-Dalsgaard, Karen K; Tyree, Melvin T

2014-05-01

300

NUCLEOSYNTHESIS IN INTERMEDIATE MASS STARS JOHN C. LATTANZIO AND CHERYL A. FROST  

E-print Network

NUCLEOSYNTHESIS IN INTERMEDIATE MASS STARS JOHN C. LATTANZIO AND CHERYL A. FROST Department AND PETER R. WOOD Mount Stromlo and Siding Springs Observatories, ANU Abstract. We discuss nucleosynthesis lagging somewhat behind. Studies are desperately needed of the nucleosynthesis which occurs during

Lattanzio, John

301

Frost hardiness vs. growth performance in trembling aspen: an experimental test of assisted migration  

E-print Network

break in populations of trembling aspen, Populus tremuloides Michx., which were observed in a large break, frost risk, leaf senescence, phenology, Populus tremuloides, provenance trial, seed transfer, trembling aspen, Populus tremuloides Michx., is one of the most widespread and genetically diverse tree

Hamann, Andreas

302

Evaluation of frost damage in cement-based materials by a nonlinear elastic wave technique  

NASA Astrophysics Data System (ADS)

Frost resistance of concrete is a major concern in cold regions. RILEM (International union of laboratories and experts in construction materials, systems and structures) recommendations provide two alternatives for evaluating frost damage by nondestructive evaluation methods for concrete like materials. The first method is based on the ultrasonic pulse velocity measurement, while the second alternative technique is based on the resonant vibration test. In this study, we monitor the frost damage in Portland cement mortar samples with water to cement ratio of 0.5 and aggregate to cement ratio of 3. The samples are completely saturated by water and are frozen for 24 hours at -25°C. The frost damage is monitored after 0, 5, 10, 15 and 20 freezing-thawing cycles by nonlinear impact resonance acoustic spectroscopy (NIRAS). The results obtained are compared with those obtained by resonant vibration tests, the second alternative technique recommended by RILEM. The obtained results show that NIRAS is more sensitive to early stages of damage than the standard resonant vibration tests.

Eiras, J. N.; Kundu, T.; Popovics, J. S.; Monzó, J.; Soriano, L.; Payá, J.

2014-03-01

303

A nano-frost array technique to prepare nanoporous PVDF membranes.  

PubMed

Frost, the solid deposition of water vapor from humid air, forms on the surface of a solid substrate when its temperature drops below the freezing point of water. In this study, we demonstrate how this natural phenomenon can be applied to develop novel nanoporous materials. The solvent annealing of polyvinylidene fluoride (PVDF) infiltrated into nanopores induced template-directed dewetting thus preparing nanoembossing films. Then, water nanodroplets formed on the cold polymer nanopatterned surfaces following the embossing patterns, similar to dew formation on the ground. Subsequently, the nanodroplets were frozen and then removed by freeze-drying. This nano-frost array technique produced nanoporous PVDF membranes with an average thickness of 250 (± 48) nm. It was revealed that the nanopatterned surface formed by solvent annealing played an important role in achieving a nano-frost array with an adjustable size. Additionally, the freezing process led to significant changes of the PVDF crystallinity and polymorphism. Our results prove that the nano-frost array technique can be broadly used to design ordered nanoporous structures and provide new prospects in nanomaterial fields. PMID:24865989

Lee, Min Kyung; Lee, Jonghwi

2014-08-01

304

Morning Frost in Trench Dug by Phoenix, Sol 113 (False Color)  

NASA Technical Reports Server (NTRS)

This image from the Surface Stereo Imager on NASA's Phoenix Mars Lander shows morning frost inside the 'Snow White' trench dug by the lander, in addition to subsurface ice exposed by use of a rasp on the floor of the trench.

The camera took this image at about 9 a.m. local solar time during the 113th Martian day of the mission (Sept. 18, 2008). Bright material near and below the four-by-four set of rasp holes in the upper half of the image is water-ice exposed by rasping and scraping in the trench earlier the same morning. Other bright material especially around the edges of the trench, is frost. Earlier in the mission, when the sun stayed above the horizon all night, morning frost was not evident in the trench.

This image is presented in false color that enhances the visibility of the frost.

The trench is 4 to 5 centimeters (about 2 inches) deep, about 23 centimeters (9 inches) wide.

Phoenix landed on a Martian arctic plain on May 25, 2008. The mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is led by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development was by Lockheed Martin Space Systems, Denver.

2008-01-01

305

Cross-Cultural Validity of the Frost Multidimensional Perfectionism Scale in Korea  

ERIC Educational Resources Information Center

This study with 213 South Korean college students (113 men) examined the cross-cultural generalizability of (a) the factor structure of the Frost Multidimensional Perfectionism Scale (F-MPS) and (b) the existence of adaptive perfectionists, maladaptive perfectionists, and nonperfectionists. A confirmatory factor analysis did not support the…

Lee, Dong-gwi; Park, Hyun-joo

2011-01-01

306

Sunlight penetration through the Martian polar caps - Effects on the thermal and frost budgets  

NASA Technical Reports Server (NTRS)

An energy balance model of the seasonal polar caps on Mars is modified to include penetration of solar radiation into and through the ice. Penetration of solar radiation has no effect on subsurface temperature or total frost sublimation if seasonal ice overlies a dust surface. An effect is noted for seasonal ice which overlies the residual polar caps. For the case of an exposed water-ice residual polar cap, the temperature at depth is calculated to be up to several degrees warmer, and the calculated lifetime of seasonal CO2 frost is slightly lower when penetration of sunlight is properly treated in the model. For the case of a residual polar cap which is perennially covered by CO2 frost, the calculated lifetime of seasonal CO2 frost is very slightly increased as a result of sunlight penetration through the ice. Hence, penetration of sunlight into the ice helps to stabilize the observed dichotomy in the residual polar caps on Mars, although it is a small effect.

Lindner, Bernhard L.

1992-01-01

307

Sunlight penetration through the Martian polar caps: Effects on the thermal and frost budgets  

NASA Technical Reports Server (NTRS)

An energy balance model of the seasonal polar caps on Mars is modified to include penetration of solar radiation into and through the ice. Penetration of solar radiation has no effect on subsurface temperature or total frost sublimation if seasonal ice overlies a dust surface. An effect is noted for seasonal ice which overlies the residual polar caps. For the case of an exposed water-ice residual polar cap, the temperature at depth is calculated to be up to several degrees warmer and the calculated lifetime of seasonal CO2 frost is slightly lower when penetration of sunlight is properly treated in the model. For the case of a residual polar cap which is perennially covered by CO2 frost, the calculated lifetime of seasonal CO2 frost is very slightly increased as a result of sunlight penetration through the ice. Hence, penetration of sunlight into the ice helps to stabilize the observed dichotomy in the residual polar caps on Mars, although it is a small effect.

Lindner, Bernhard Lee

1992-01-01

308

An Evaluation of the Factor Structure of the Frost Multidimensional Perfectionism Scale  

ERIC Educational Resources Information Center

The purpose of the study was to investigate whether the six-factor structure of the Frost Multidimensional Perfectionism Scale could be replicated in a community-based sample. A sample of 255 adult participants (55.7% female, 44.3% male) ranging in age from 18 to 78 (mean = 37.0) completed the questionnaire. Based on the screen test and parallel…

Harvey, Bronwyn; Pallant, Julie; Harvey, David

2004-01-01

309

FrostWall: a Dual-Sided Situated Display for Informal Collaboration in the Corridor  

E-print Network

to support collegial communication and collaboration within a co-located work environment by facilitating and encouraging informal information exchange in the corridors of a workplace using large situated displays. Frost and operable from both sides. In addition to facilitating informal digital communication and information

Thomas, Bruce

310

Improving frost-simulation subroutines of the Water Erosion Prediction Project (WEPP) model  

Technology Transfer Automated Retrieval System (TEKTRAN)

Erosion models play an important role in assessing the influence of human activities on the environment. For cold areas, adequate frost simulation is crucial for predicting surface runoff and water erosion. The Water Erosion Prediction Project (WEPP) model, physically-based erosion-prediction softwa...

311

Frost action of freezing ground surrounding underground storage of a cold liquid  

Microsoft Academic Search

A small tank in the shape of a cylinder 80 cm in diameter and 50 cm in depth was placed in a basin, filled with a silty soil, of the frost test field in Tomakomai, Hokkaido Japan, with its top at the same level as the ground surface in the basin. The double wall (two steel sheets 10 cm apart)

S. Kinosita; M. Fukuda; T. Ishizaki; H. Yamamoto

1982-01-01

312

Radiation frost susceptibility and the association between sky exposure and leaf size  

Microsoft Academic Search

Plants growing in exposed and sheltered habitats have characteristic leaf structure and physiology that are traditionally associated with the total amount of incident sunlight. However, greater sky exposure also increases the susceptibility of leaves to radiation frost. Plants with large horizontal broadleaves are particularly susceptible to both overheating during the day and freezing at night. Moreover, the combined effects of

Dean N. Jordan; William K. Smith

1995-01-01

313

The Late Spring Frost Hardiness of Some Apple Varieties at Various Stages of Flower Buds  

Microsoft Academic Search

In this study, survival rates of pistils of seven apple (Malus x domestica Borkh.) varieties at various stages from tight cluster to full bloom on trees were determined after frost that occurred on the morning at 3:00-8:00 of April 17, 2004 when the temperature dropped to -4 to -6 o C in the orchard. The survival rates of pistils of

Ahmet AYGÜN

314

Old World Monkeys Stephen R Frost, University of Oregon, Eugene, Oregon, USA  

E-print Network

Old World Monkeys Stephen R Frost, University of Oregon, Eugene, Oregon, USA Alfred L Rosenberger) article, Old World Monkeys by Walter Carl Hartwig and Alfred L Rosenberger. Old World monkeys (hominoids) than they are to the monkeys of Central and South America. Introduction Old World monkeys

Rosenberger, Alfred H.

315

Variation among highbush blueberry cultivars for frost tolerance of open flowers  

Technology Transfer Automated Retrieval System (TEKTRAN)

Injury of open flowers often occurs in fruit crops by late winter or early spring frosts and can result in significant reduction in yield. In this study, freezing tolerance of open flowers of five highbush blueberry cultivars, ‘Bluecrop’, ‘Elliott’, ‘Hannah’s Choice’, ‘Murphy’, and ‘Weymouth’, was d...

316

Pancakes, Puzzles, and Polynomials: Cracking the Cracker Barrel Christopher Frost, Michael Peck, David Evans  

E-print Network

Pancakes, Puzzles, and Polynomials: Cracking the Cracker Barrel Christopher Frost, Michael Peck, evans]@cs.virginia.edu Abstract The Cracker Barrel peg game is a simple, one-player game commonly found Board Game Leave only one -- you're genius, . . . Leave four or more'n you're just plain "eg

Evans, David

317

Pancakes, Puzzles, and Polynomials: Cracking the Cracker Barrel Christopher Frost, Michael Peck, David Evans  

E-print Network

Pancakes, Puzzles, and Polynomials: Cracking the Cracker Barrel Christopher Frost, Michael Peck The Cracker Barrel peg game is a simple, one-player game commonly found on tables at pancake restaurants of a generalization of the problem is NP-complete. 1 The Peg Board Game Leave only one -- you're genius, . . . Leave

Evans, David

318

Experimental study on frosting suppression for a finned-tube evaporator using ultrasonic vibration  

Microsoft Academic Search

An experimental study was conducted to investigate the possibility and the effect of frost release from a finned-tube evaporator by using ultrasonic vibrations in natural convection. A compressor was adopted as cold source, and a finned-tube evaporator was placed horizontal on the frames inside a chamber. The aluminum fins surface was covered with hydrophilic coatings whose contact angle of the

Dingyuan Wang; Tangfei Tao; Guanghua Xu; Ailing Luo; Shaoying Kang

319

BEST PRACTICES RESEARCH 2014 Frost & Sullivan 1 "We Accelerate Growth"  

E-print Network

for Virtual Private LAN Services (VPLS) continues to be modest, as most enterprises continue to prefer Layer 3TM methodology. This unique approach enables us to determine how best-in-class companies worldwide manage growth to AT&T. Key Industry Challenges Carrier Ethernet continues to gain acceptance among enterprises, due

Fisher, Kathleen

320

Sensitivity of frost occurrence to temperature variability in the European Alps  

NASA Astrophysics Data System (ADS)

In this study, we set out to investigate the linkage of frost frequency to monthly mean temperature and its sensitivity to temperature changes. According to other related studies, the linkage between frost frequency and monthly mean temperature is approximated month per month via hyperbolic tangent functions. These models are validated using three validation experiments including split sample tests and temporal cross-validation. As there are quality-checked station data in Austria, whose temporal resolution and length allow for such a validation procedure, the validation experiments are conducted there.After the performance of the empirical models is evaluated and found adequate, the hyperbolic tangent approach is applied to about 500 stations within the so called Greater Alpine region (GAR), which extends from about 4 °E to 18 °E and from 44 °N to 49 °N. Using these models, it is possible to derive the sensitivity of frost frequency for any location for which the annual temperature cycle is known. This strategy is explicitly demonstrated for the Po Plain, where vertical temperature profiles on a monthly base are on hand as well as in Austria, where spatially high resolved maps of monthly mean temperature are available. Moreover, at stations for which long-term homogenised series of monthly mean temperature are available, reconstructions of frost frequency via the empirical models are done, returning to historical periods where no measurements of minimum temperature exist.On the basis of these findings, the impact of a possible future warming can be assessed, which is essential with regard to glaciers, permafrost and avalanches. Reduction in frost might bring positive economic aspects for agriculture, but negative consequences for low level skiing areas. Copyright

Auer, Ingeborg; Matulla, Christoph; Böhm, Reinhard; Ungersböck, Markus; Maugeri, Maurizio; Nanni, Teresa; Pastorelli, Rossella

2005-11-01

321

Developing a phenological model for grapevine to assess future frost risk in Luxembourg  

NASA Astrophysics Data System (ADS)

Late frost damage represents a significant hazard to grape production in cool climate viticulture regions such as Luxembourg. The main aim of our study is to analyze the frequency of these events for the Luxembourg's winegrowing region in the future. Spring frost injuries on grape may occur when young green parts are exposed to air temperature below 0°C. The potential risk is determined by: (i) minimum air temperature conditions and the (ii) the timing of bud burst. Therefore, we developed and validated a model for budburst of the grapevine (*Vitis vinifera)* cultivar Rivaner, the most grown local variety, based on multi-annual data from 7 different sites across Europe and the US. An advantage of this approach is, that it could be applied to a wide range of climate conditions. Higher spring temperatures were projected for the future and could lead to earlier dates of budburst as well as earlier dates of last frost events in the season. However, so far it is unknown if this will increase or decrease the risk of severe late frost damages for Luxembourg's winegrowing region. To address this question results of 10 regional climate change projections from the FP6 ENSEMBLES project (spatial resolution = 25km; A1B emission scenario) were combined with the new bud burst model. The use of a multi model ensemble of climate change projections allows for a better quantification of the uncertainties. A bias corrections scheme, based on local observations, was applied to the model output. Projected daily minimum air temperatures, up to 2098, were compared to the projected date of bud burst in order to quantify the future frost risk for Luxembourg.

Caffarra, A.; Molitor, D.; Pertot, I.; Sinigoy, P.; Junk, J.

2012-04-01

322

Presence service in IMS.  

PubMed

This paper describes the presence service, which is located in the IP multimedia subsystem. This service allows making many applications for different groups of people. The paper describes differences between a network without the service and with the service. The biggest change is an increased number of transmitted messages. The presence uses some part of the IP multimedia subsystem control layer, which is shown in communication between the user and the server. The paper deals with the number of generated messages depending on the behaviour of the users. This is described by a mathematical model using discrete Markov chains. PMID:23970836

Petras, David; Baronak, Ivan; Chromy, Erik

2013-01-01

323

Presence Service in IMS  

PubMed Central

This paper describes the presence service, which is located in the IP multimedia subsystem. This service allows making many applications for different groups of people. The paper describes differences between a network without the service and with the service. The biggest change is an increased number of transmitted messages. The presence uses some part of the IP multimedia subsystem control layer, which is shown in communication between the user and the server. The paper deals with the number of generated messages depending on the behaviour of the users. This is described by a mathematical model using discrete Markov chains. PMID:23970836

Petras, David

2013-01-01

324

Electric Field and Plasma Density Observations of Long Wavelength Structures and Localized Packets of Short Scale Waves Associated with Sporadic-E Layers in the Presence of QP Radar Echoes  

NASA Astrophysics Data System (ADS)

Electric field and plasma density data gathered on sounding rockets launched in the presence of sporadic-E layers and QP radar echoes reveal a complex electrodynamics including both DC parameters and plasma waves detected over a large range of scales. We present results from two different sounding rocket experiments equipped with similar instrumentation which were conducted in the presence of intense QP radar echoes: a NASA sporadic-E investigation launched from Wallops Island, Va., in 1999 and the Japanese "SEEK-2" rocket launched from Uchinoura, Japan in 2002. Electric field data from both experiments reveal the presence of km-scale waves as well as well-defined packets of broadband (10's of meters to meters) irregularities. What is surprising is that in both experiments, neither the large scale nor short scale waves appear to be distinctly organized by the sporadic-E density layer. Data from the NASA rocket revealed large scale structures with wavelengths of 2-4 km and amplitudes of 1-2 mV/m that were most intense in the region of 90-110 km during the downleg trajectory of this flight. The waves were oriented in the NE-SW quadrants. On the other hand, during the SEEK-2 experiment, the electric field data above the sporadic-E layer on the upleg, from 110 km to the rocket apogee of 151 km, revealed a continuous train of distinct, large scale, quasi-periodic structures with wavelengths of 10-15 km that also propagated between the NE-SW quadrants. The electric field structures had typical amplitudes of 3-5 mV/m with some excursions to 8-9 mV/m, and had associated perturbations in the plasma density. The electric field waveforms showed evidence for steepening and/or convergence effects and may have mapped upwards along the magnetic field from the sporadic-E region below. Candidate mechanisms to explain the origin of these structures include the Kelvin-Helmholtz instability and the Es Layer instability. In both cases, the same shear that formed the sporadic-E layer would presumably provide the energy to generate the km-scale structures. Other possibilities include a gravity wave explanation or a combination of these processes. The data suggest that these structures were associated with the lower altitude density striations that were the seat of the QP radar echoes observed simultaneously. The SEEK-2 structures may also have been associated with the mechanism responsible for a well-defined pattern of "whorls" in the neutral wind data that were revealed in a chemical trail released by a second sounding rocket launched 15 minutes later. Well-defined packets of higher frequency (shorter scales < 100 m) broadband waves were also observed in-situ on both rockets, consistent with the observations of intense radar backscatter during the times of each launch. The linear gradient drift instability involving the DC electric field and the vertical plasma gradient is shown to be incapable of driving most, although not all, of the short scale waves observed during each flight. The data suggest that other sources of free energy may have been important factors for wave growth, and we conclude that drift waves associated with winds and horizontal plasma density gradients, as well as thermal or other instabilities, are necessary to explain the short-scale wave generation observed during these sporadic-E encounters.

Pfaff, R. F.; Freudenreich, H.; Kudeki, E.; Larsen, M.

2006-05-01

325

Polar Layers and Dunes  

NASA Technical Reports Server (NTRS)

23 July 2004 Acquired just a few days ago on 21 July 2004, this 1.7 m/pixel (5.6 ft/pixel) Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows layer outcrops and sand dunes in the Chasma Boreale portion of the martian north polar cap. At this time, it is spring and these polar landforms are still covered by frost left over from the winter that ended back in March 2004. In summer, the dunes in this image will be darker than anything else in the scene. The picture is located near 85.1oN, 3.7oW, and covers an area about 1.5 km (0.9 mi) wide. This view is illuminated by sunlight from the upper right.

2004-01-01

326

Influence of supermarket environmental parameters on the frosting and defrosting of vertical multideck display cabinets  

SciTech Connect

This paper reports on results of investigations to identify and quantify the effect of in-store environmental conditions on frost accumulation on the evaporator coils of open multideck refrigerated display cabinets. Field and environmental chamber-based tests have shown that both ambient relative humidity and temperature of a store have a significant effect on the rate of frost formation on the evaporator coils, with the effect of relative humidity being much more pronounced than the effect of temperature. In supermarkets where a fixed-time defrost control strategy is employed, it is possible that cabinets are defrosted too infrequently at high relative humidities, resulting in high product temperatures, and too frequently at low relative humidities, resulting in excessive energy consumption. Considerable opportunity exists for the application of more sophisticated defrost control strategies, both to save energy and improve temperature control.

Tassou, S.A.; Datta, D.

1999-07-01

327

EVALUATION OF FROST HEAVE ON WASTE TRANSFER LINES WITH SHALLOW DEPTHS IN DST (DOUBLE SHELL TANK) FARMS  

SciTech Connect

The purpose of this document is to evaluate the effect of frost heave on waste transfer lines with shallow depths in DST farms. Because of the insulation, well compacted sandy material around waste transfer lines, the type of sandy and gravel soil, and relatively low precipitation at Hanford site, it is concluded that waste transfer lines with one foot of soil covers (sandy cushion material and insulation) are not expected to undergo frost heave damaging effects.

HAQ MA

2009-05-12

328

Dynamics of low velocity collisions of ice particle, coated with frost  

NASA Technical Reports Server (NTRS)

We continued our investigations of low velocity collisions of ice particles for velocities in range 10(exp -3) - 2 cm/s. The work focused on two effects: (1) the sticking forces for ice particles coated with CO2 frost, and (2) the completion of a 2-D pendulum system for glancing collisions. A new computer software was also developed to control and monitor the position of the 2-D pendulum.

Bridges, F.; Lin, D.; Boone, L.; Darknell, D.

1991-01-01

329

Balloon borne observations of PSCs, Frost Point, ozone and nitric acid in the north polar vortex  

Microsoft Academic Search

A new balloon borne instrument called a backscattersonde has been used to study Polar Stratospheric Clouds (PSCs) at Alert, NWT (82°N, 61.5°W) during January and February of 1989. These measurements were supplemented with frost point, ozone and nitric acid vapor soundings. Type I PSCs were observed at temperatures and pressures generally consistent with present vapor pressure models of HNOâ\\/HâO condensate,

James M. Rosen; S. J. Oltmans; W. F. Evans

1989-01-01

330

Experimental investigation of effect of admmixture on concrete strength and frost-resistance  

Microsoft Academic Search

The influence of admixture on concrete strength and frost-resistance was analyzed by using the mercury intrusion method and the rapid frozen-thaw method under the condition of the same water\\/binder ratio in this paper. The results showed that the intensity of the concrete with single doped compound mineral admixture is slightly lower than the normal concrete's in concrete 28-days strength experiment

Ying Zhang; Jiang-dong Cai; Shan-lin Xu; Chen-xi Yue

2011-01-01

331

Anthocyanins and glutathione S-transferase activities in response to low temperature and frost hardening in Vaccinium myrtillus (L.).  

PubMed

Anthocyanin (Acy) contents and GST activities of bilberry (Vaccinium myrtillus L.) were investigated in two experiments conducted in June (Exp. I: active growth) and in August September (Exp. II: beginning of frost hardening) in Northern Finland (65 degrees N). Bilberry plants were subjected to +2 degrees C and +18 degrees C in Exp. I or +5/0 degrees C (day/night) and +18/+13 degrees C (day/night) in Exp. II. GST activities were assessed using either 1-chloro-2,4-dinitrobenzene (CDNB) or trans-cinnamic acid (tCA) as substrates. We found temperature to have no effect on Acy during either active growth or frost hardening. Acy increased several-fold from active growth to the beginning of frost hardening, but no increment was observed during the development of frost hardening. This suggests a role of Acy in photoprotection at low temperatures rather than their direct involvement in the development of freezing tolerance. The lack of response of GST activity to frost hardening and to temperature in autumn may indicate an indirect role of GSTs in frost hardening as protective enzymes. GST activity was the same with the two substrates studied (CDNB, tCA), supporting the assumption that GSTs could catalyze reactions with endogenous phenylpropanoids. PMID:15384401

Taulavuori, Erja; Tahkokorpi, Marjaana; Taulavuori, Kari; Laine, Kari

2004-08-01

332

Decadal predictability of frost days in the MPI-ESM-LR model  

NASA Astrophysics Data System (ADS)

The number of frost days (days with minimum temperature below 0°C) is a typical index for cold temperature extremes defined by the Joint CCl/CLIVAR/JCOMM Expert Team on Climate Change Detection and Indices (ETCCDI). It's predictability on inter-annual to decadal time scales bears economic and societal relevance, e.g. as basis for energy or agricultural policy planning. As part of the MiKlip initiative for decadal prediction, annually initialised ensemble hindcast experiments with the Max-Planck-Institute Earth System Model in a low resolution configuration (MPI-ESM-LR, T63L47) have been carried out. For a period of 35 years (1961-1995) we analyze the number of frost days per season and grid point on a 5° x 5° longitude-latitude grid for the northern hemisphere stemming from ten/three ensemble member hindcasts produced with two different initialisation strategies. The ensembles are interpreted as probabilistic predictions of historically equiprobable three-category events (below normal, normal, above normal) and as such are compared to frost day counts from HadEx2 and the 20th Century Reanalysis. Prediction skill over climatological forecasts and uninitialised climate projections is assessed for various lead times using the Ranked Probability Skill Score (RPSS).

Kröner, Igor; Kruschke, Tim; Rust, Henning W.; Ulbrich, Uwe

2014-05-01

333

The role of permafrost and seasonal frost in the hydrology of northern wetlands in North America  

USGS Publications Warehouse

Wetlands are a common landscape feature in the Arctic, Subarctic, and north Temperate zones of North America. In all three-zones, the occurrnce of seasonal frost results in similar surface-water processes in the early spring. For example, surface ice and snow generally melt before the soil frost thaws, causing melt water to flow into depressions, over the land surface and at times, across low topographic divides. However, evapotranspiration and ground-water movement differ among the three climatic zones because they are more affected by permafrost than seasonal frost. The water source for plants in the Arctic is restricted to the small volume of subsurface water lying above the permafrost. Although this is also true in the Subarctic where permafrost exists, where it does not, plants may receive and possibly reflect, more regional ground-water sources. Where permafrost exists, the interaction of wetlands with subsurface water is largely restricted to shallow local flow systems. But where permafrost is absent in parts of the Subarctic and all of the Temperature zone, wetlands may have a complex interaction with ground-water-flow systems of all magnitudes. ?? 1993.

Woo, M.-K.; Winter, T.C.

1993-01-01

334

Balloon borne Antarctic frost point measurements and their impact on polar stratospheric cloud theories  

NASA Technical Reports Server (NTRS)

The first balloon-borne frost point measurements over Antarctica were made during September and October, 1987 as part of the NOZE 2 effort at McMurdo. The results indicate water vapor mixing ratios on the order of 2 ppmv in the 15 to 20 km region which is somewhat smaller than the typical values currently being used significantly smaller than the typical values currently being used in polar stratospheric cloud (PSC) theories. The observed water vapor mixing ratio would correspond to saturated conditions for what is thought to be the lowest stratospheric temperatures encountered over the Antarctic. Through the use of available lidar observations there appears to be significant evidence that some PSCs form at temperatures higher than the local frost point (with respect to water) in the 10 to 20 km region thus supporting the nitric acid theory of PSC composition. Clouds near 15 km and below appear to form in regions saturated with respect to water and thus are probably mostly ice water clouds although they could contain relatively small amounts of other constituents. Photographic evidence suggests that the clouds forming above the frost point probably have an appearance quite different from the lower altitude iridescent, colored nacreous clouds.

Rosen, James M.; Hofmann, D. J.; Carpenter, J. R.; Harder, J. W.; Oltmans, S. J.

1988-01-01

335

Identification of frost susceptible aggregates and their use in concrete or bituminous pavements  

SciTech Connect

Coarse aggregates have been recognized as potential sources of deterioration of concrete exposed to freezing and thawing action. Whenever coarse aggregates are involved, deterioration of pavement structures can take place as pitting, pop-outs, and varying extents of D-cracking. Recently, serious damage of bituminous pavements was observed where the coarse aggregate fraction played an important role. In some concrete and bituminous pavements, a typical pattern of surface damage was also found associated to the application of deicers. In order to prevent damage to concrete and bituminous pavements by frost susceptible aggregates, they must be identified by reliable testing procedures. The present study was designed to investigate the significance of the details of the pore structure on the frost resistance of concrete aggregates. Likewise, the surface failure taking place in concrete and bituminous pavements exposed to deicers was closely analyzed. Based on field data, a discriminating function was obtained to differentiate between aggregates of varying frost resistance. This function was derived by taking into consideration the details of the pore structure of coarse aggregates in concrete pavements.

Salcedo, M.A.

1984-01-01

336

Mechanism of delayed frost growth on superhydrophobic surfaces with jumping condensates: more than interdrop freezing.  

PubMed

Delayed frost growth on superhydrophobic surfaces (SHSs) with jumping condensates has been found by many researchers recently. However, the mechanism of this phenomenon has not been elucidated clearly. In this study, copper SHSs with or without jumping condensates were selected as the substrates for observing condensation icing at a relative humidity (RH) of 60%. The results showed that only SHS with jumping condensates showed delayed condensation icing. Moreover, when such SHSs were placed upward and the surface temperature was held at -10 °C, some discrete frozen drops first appeared on the SHSs. The following icing mainly occurred on these discrete global crystals and then expanded around them until covering the entire surface. Little macroscopic interdrop freezing phenomenon was found. The growth of the frost front is mainly dominated by jumping freezing (the condensed droplets jumped onto the ice crystals and were frozen) or direct vapor-ice deposition. Using microscopy, we found interdrop freezing occurred, in addition to the two mechanisms mentioned above. By placing the SHS downward at -10 °C and intentionally introducing or eliminating tiny dusts, we confirmed that there were no superhydrophobic defects on our SHSs. The discrete frozen drops first appearing on the SHSs were triggered by tiny dusts falling on the surface before or during condensation icing. The key approach in delaying or resisting frost growth on SHSs with jumping condensates is to retard initial ice crystal formation, e.g., eliminating the edge effect and keeping the SHSs clean. PMID:25466489

Hao, Quanyong; Pang, Yichuan; Zhao, Ying; Zhang, Jing; Feng, Jie; Yao, Shuhuai

2014-12-30

337

Frost damage in citric and olive production as the result of climate degradation  

NASA Astrophysics Data System (ADS)

Low temperature is one of the chief limiting factors in plant distribution. Freezing temperature shortens the growing season and may lower the yield and quality of any number of fruit crops. Minimum temperatures records for the Spanish region of Murcia were studied as limiting factor in fruit production. An analysis of temperature series since 1935 showed that the range of the absolute minimum temperatures (Tmin) on frost days in the target year, namely -0.5 °C to -4.0°C, was statistically similar to the range recorded in 1993, while the mean minimum temperatures (tmin) were found to have risen. The historical series also showed the mean minimum temperatures (tmin) to have increased, however. Through 1985, tmin ranged from 4.0 to -2.0 °C, depending on the area, while these limits shifted in more recent years to 7.0 - 0.5 °C. This increase in mean temperature produced that the frost episodes in March 2004 was considered by lemon, mandarin and olive producers as the worst in many years for frost damage since the minimum temperature was reached in a more sensitive phenological stage, despite the statistical evidence that similar freezing temperatures had been reached on similar dates in other years.

Saa Requejo, A.; Díaz Alvarez, M. C.; Tarquis, A. M.; Burgaz Moreno, F.; Garcia Moreno, R.

2009-04-01

338

Effects of chemical reaction, heat and mass transfer on an unsteady mixed convection boundary layer flow over a wedge with heat generation/absorption in the presence of suction or injection  

NASA Astrophysics Data System (ADS)

The purpose of this work is to study the effects of chemical reaction, heat and mass transfer on an unsteady mixed convection boundary layer flow over a vertical wedge with heat generation/absorption in the presence of uniform suction or injection. The fluid is assumed to be viscous and incompressible. The unsteadiness is caused by the time dependent free stream velocity varying arbitrarily with time. Both accelerating and decelerating free stream flows are considered. Non-similar solutions are obtained numerically by using an implicit finite difference scheme in combination with the quasi-linearization technique. Numerical computations are carried out for different values of dimensionless parameters on velocity, temperature and concentration profiles graphically reported in the present study. Also, numerical results are presented for the local skin friction coefficient, the local Nusselt number and the local Sherwood number. Results indicate that the time effect is crucial on velocity, temperature and concentration profiles, and on the local skin friction coefficient, the local Nusselt and Sherwood numbers. The buoyancy assisting force causes overshoot in the velocity profile for lower Prandtl number fluids. Results are compared with previously published work and are found to be in an excellent agreement.

Ganapathirao, M.; Ravindran, R.; Momoniat, E.

2015-02-01

339

Effects of chemical reaction, heat and mass transfer on an unsteady mixed convection boundary layer flow over a wedge with heat generation/absorption in the presence of suction or injection  

NASA Astrophysics Data System (ADS)

The purpose of this work is to study the effects of chemical reaction, heat and mass transfer on an unsteady mixed convection boundary layer flow over a vertical wedge with heat generation/absorption in the presence of uniform suction or injection. The fluid is assumed to be viscous and incompressible. The unsteadiness is caused by the time dependent free stream velocity varying arbitrarily with time. Both accelerating and decelerating free stream flows are considered. Non-similar solutions are obtained numerically by using an implicit finite difference scheme in combination with the quasi-linearization technique. Numerical computations are carried out for different values of dimensionless parameters on velocity, temperature and concentration profiles graphically reported in the present study. Also, numerical results are presented for the local skin friction coefficient, the local Nusselt number and the local Sherwood number. Results indicate that the time effect is crucial on velocity, temperature and concentration profiles, and on the local skin friction coefficient, the local Nusselt and Sherwood numbers. The buoyancy assisting force causes overshoot in the velocity profile for lower Prandtl number fluids. Results are compared with previously published work and are found to be in an excellent agreement.

Ganapathirao, M.; Ravindran, R.; Momoniat, E.

2014-07-01

340

The Role of Eolian Processes in Forming Surface Features of the Martian Polar Layered Deposits  

Microsoft Academic Search

The major topographic features of the martian polar layered deposits include the conspicuous spiral troughs, subtle undulations, broad reentrants (chasma), steep, arcuate scarps, and dune fields. A prominent role for eolian processes in the formation of all of these features is proposed. Strong katabatic winds occur on the north polar cap, producing widespread frost streaks. These cold drainage winds are

Alan D. Howard

2000-01-01

341

Measuring the Size of a Small, Frost World  

NASA Astrophysics Data System (ADS)

Observing a very rare occultation of a star by Pluto's satellite Charon from three different sites, including Paranal, home of the VLT, astronomers were able to determine with great accuracy the radius and density of the satellite to the farthest planet. The density, 1.71 that of water, is indicative of an icy body with about slightly more than half of rocks. The observations also put strong constraints on the existence of an atmosphere around Charon. ESO PR Photo 02a/06 ESO PR Photo 02a/06 Artist's Impression of the Pluto-Charon system Since its discovery in 1978, Charon and Pluto have appeared to form a double planet, rather than a planet-satellite couple. Actually, Charon is about twice as small as Pluto in size, and about eight times less massive. However, there have been considerable discussions concerning the precise radii of Pluto and Charon, as well as about the presence of a tenuous atmosphere around Charon. In August 2004, Australian amateur astronomer Dave Herald predicted that the 15-magnitude star UCAC2 26257135 should be occulted by Charon on 11 July 2005. The occultation would be observable from some parts of South America, including Cerro Paranal, in the northern Atacama Desert, the location of ESO's Very Large Telescope (VLT). Stellar occultations have proved to be powerful tools to both measure sizes - at km-level accuracy, i.e. a factor ten better than what is feasible with other techniques - and detect very tenuous atmosphere - at microbar levels or less. Unfortunately, in the case of Charon, such occultations are extremely rare, owing to the very small angular diameter of the satellite on the sky: 55 milli-arcsec, i.e. the size of a one Euro coin observed from 100 km away! This explains why only one occultation by Charon was ever observed before 2005, namely on 7 April 1980 by Alistair Walker, from the South Africa Astronomical Observatory. Similarly, only in 1985, 1988 and 2002 could astronomers observe stellar occultations by Pluto. Quite surprisingly, the 2002 event showed that Pluto's atmospheric pressure had increased by a factor of two in four years (ESO PHOT 21/02). "Several factors, however, have boosted our odds for witnessing occultations of Charon," said Bruno Sicardy, from Paris Observatory (France) and lead author of the paper reporting the results. "First, larger telescopes now give access to fainter stars, thus multiplying the candidates for occultations. Secondly, stellar catalogues have become much more precise, allowing us to do better predictions. And, finally, the Pluto-Charon system is presently crossing the Milky Way, thereby increasing the likelihood of an occultation." ESO PR Photo 02b/06 ESO PR Photo 02b/06 The Pluto-Charon System (NACO/VLT) The July 2005 event was eventually observed from Paranal with Yepun, the fourth Unit Telescope of the VLT, equipped with the adaptive optics instrument NACO, as well as with the 0.5m "Campo Catino Austral Telescope" at San Pedro de Atacama (Chile), and with the 2.15m "Jorge Sahade" telescope at Cerro El Leoncito (Argentina). An accurate timing of the occultation seen at the three sites provides the most accurate measurement of Charon's size: its radius is found to be 603.6 km, with an error of the order of 5 km. This accuracy now allows astronomers to pin Charon's density down to 1.71 that of water, indicative of an icy body with about slightly more than half of rocks. Quite remarkably, Charon's density is now measured with much more precision than Pluto's. ESO PR Photo 02c/06 ESO PR Photo 02c/06 Charon's Occultation on July 11, 2005 Thanks to these observations, Sicardy and his collaborators could determine that if an tenuous atmosphere exists on Charon, linking it to the freezing ­-220­ degrees centigrade or so surface, its pressure has to be less than one tenth of a millionth that at the surface of the Earth, or 0.1 microbar, assuming that it is constituted entirely of nitrogen. A similar upper limit is derived for a gas like carbon monoxide. This is more than a factor one hundred smaller than

2006-01-01

342

Seasonal to Decadal Variations of Water Vapor in the Tropical Lower Stratosphere Observed with Balloon-Borne Cryogenic Frost Point Hygrometers  

NASA Technical Reports Server (NTRS)

We investigated water vapor variations in the tropical lower stratosphere on seasonal, quasi-biennial oscillation (QBO), and decadal time scales using balloon-borne cryogenic frost point hygrometer data taken between 1993 and 2009 during various campaigns including the Central Equatorial Pacific Experiment (March 1993), campaigns once or twice annually during the Soundings of Ozone and Water in the Equatorial Region (SOWER) project in the eastern Pacific (1998-2003) and in the western Pacific and Southeast Asia (2001-2009), and the Ticosonde campaigns and regular sounding at Costa Rica (2005-2009). Quasi-regular sounding data taken at Costa Rica clearly show the tape recorder signal. The observed ascent rates agree well with the ones from the Halogen Occultation Experiment (HALOE) satellite sensor. Average profiles from the recent five SOWER campaigns in the equatorial western, Pacific in northern winter and from the three Ticosonde campaigns at Costa Rica (10degN) in northern summer clearly show two effects of the QBO. One is the vertical displacement of water vapor profiles associated with the QBO meridional circulation anomalies, and the other is the concentration variations associated with the QBO tropopause temperature variations. Time series of cryogenic frost point hygrometer data averaged in a lower stratospheric layer together with HALOE and Aura Microwave Limb Sounder data show the existence of decadal variations: The mixing ratios were higher and increasing in the 1990s, lower in the early 2000s, and probably slightly higher again or recovering after 2004. Thus linear trend analysis is not appropriate to investigate the behavior of the tropical lower stratospheric water vapor.

Fujiwara, M.; Voemel, H.; Hasebe, F.; Shiotani, M.; Ogino, S.-Y.; Iwasaki, S.; Nishi, N.; Shibata, T.; Shimizu, K.; Nishimoto, E.; ValverdeCanossa, J. M.; Selkirk, H. B.; Oltmans, S. J.

2010-01-01

343

Patches of Remnant Frost/Snow on Crater Rim in Northern Summer  

NASA Technical Reports Server (NTRS)

March 1999--it is summer in the martian northern hemisphere, yet patches of frost or snow persist in some areas of the northern plains. Winter ended eight months earlier, in July 1998. Recently, the Mars Orbiter Camera (MOC) passed over a relatively small impact crater located at latitude 68oN (on the Vastitas Borealis plain, north of Utopia Planitia) and took the picture seen at the left, above. The curved crater rims are visible in the upper and lower quarters of the image, and the crater floor is visible at the center right.

The picture on the right is a magnified view of the crater rim area outlined by a white box in the image on the left. The bright patches are snow or frost left over from the martian winter. These snowfields are so small that a human could walk across one of them in a matter of minutes--or perhaps sled down the small, sloping patch that is seen in a shadowed area near the lower left.

In winter, the entire scene shown here would be covered by frost. The long strip at the left covers an area 3 km (1.9 mi) wide by 26 km (16 mi) long. The expanded view on the right covers an area 2.9 km (1.8 mi) by 5.3 km (3.3 mi). Illumination is from the upper right.

Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.

1999-01-01

344

Liquid-infused nanostructured surfaces with extreme anti-ice and anti-frost performance.  

PubMed

Ice-repellent coatings can have significant impact on global energy savings and improving safety in many infrastructures, transportation, and cooling systems. Recent efforts for developing ice-phobic surfaces have been mostly devoted to utilizing lotus-leaf-inspired superhydrophobic surfaces, yet these surfaces fail in high-humidity conditions due to water condensation and frost formation and even lead to increased ice adhesion due to a large surface area. We report a radically different type of ice-repellent material based on slippery, liquid-infused porous surfaces (SLIPS), where a stable, ultrasmooth, low-hysteresis lubricant overlayer is maintained by infusing a water-immiscible liquid into a nanostructured surface chemically functionalized to have a high affinity to the infiltrated liquid and lock it in place. We develop a direct fabrication method of SLIPS on industrially relevant metals, particularly aluminum, one of the most widely used lightweight structural materials. We demonstrate that SLIPS-coated Al surfaces not only suppress ice/frost accretion by effectively removing condensed moisture but also exhibit at least an order of magnitude lower ice adhesion than state-of-the-art materials. On the basis of a theoretical analysis followed by extensive icing/deicing experiments, we discuss special advantages of SLIPS as ice-repellent surfaces: highly reduced sliding droplet sizes resulting from the extremely low contact angle hysteresis. We show that our surfaces remain essentially frost-free in which any conventional materials accumulate ice. These results indicate that SLIPS is a promising candidate for developing robust anti-icing materials for broad applications, such as refrigeration, aviation, roofs, wires, outdoor signs, railings, and wind turbines. PMID:22680067

Kim, Philseok; Wong, Tak-Sing; Alvarenga, Jack; Kreder, Michael J; Adorno-Martinez, Wilmer E; Aizenberg, Joanna

2012-08-28

345

Acclimation to frost alters proteolytic response of wheat seedlings to drought.  

PubMed

A comparative examination of cysteine proteinases in winter wheat (Triticum aestivum L.) seedlings differing in sensitivity to frost and drought revealed many similarities and differences in response to water deprivation. Azocaseinolytic activity was enhanced under water deficiency, but the enhancement was significantly lower in the tolerant genotype (Kobra cultivar). On the contrary, acclimation of wheat seedlings at low temperature had no effect on the proteolytic activity of the tolerant cultivar and depressed the azocaseinolytic activity of the sensitive cultivar (Tortija). However, the observed depression of enzyme activity was fully reversible under dehydration. The content of soluble proteins was reduced in dehydrated non-acclimated and in acclimated seedlings of the frost-sensitive cultivar, but increased in acclimated seedlings of the tolerant cultivar. The cysteine proteinases were preferentially induced under water deficiency when assessment was based on the inhibitory effect of iodoacetate on azocasein hydrolysis. Separation of cysteine proteinases by SDS-PAGE containing gelatin as a substrate showed two bands with apparent molecular masses of 36 and 38 kDa in the sensitive cultivar, and a third band was detected (42 kDa) in the resistant cultivar. Water deficit and low temperature induced the new cysteine proteinases of molecular masses about 29, 33 and 42 kDa in sensitive non-acclimated seedlings. Polyclonal antibodies raised against Arabidopsis proteinase responsive to drought (RD21) cross-reacted with the protein in the 33 kDa region, and a slight signal was obtained in the 42 kDa region, but only in dehydrated seedlings acclimated to frost. Several polypeptides of molecular masses of 30, 22, 20 and 18 kDa were recognized by the Arabidopsis aleurain-like proteinase (AtALEU) antibodies. The results presented indicate that cysteine proteinases are potentially responsible for both low temperature and drought tolerance. PMID:20674076

Grudkowska, Ma?gorzata; Zagda?ska, Barbara

2010-11-01

346

CLAS+FROST: new generation of photoproduction experiments at Jefferson Lab  

E-print Network

A large part of the experimental program in Hall B of the Jefferson Lab is dedicated to baryon spectroscopy. Photoproduction experiments are essential part of this program. CEBAF Large Acceptance Spectrometer (CLAS) and availability of circularly and linearly polarized tagged photon beams provide unique conditions for this type of experiments. Recent addition of the Frozen Spin Target (FROST) gives a remarkable opportunity to measure double and triple polarization observables for different pseudo-scalar meson photoproduction processes. For the first time, a complete or nearly complete experiment becomes possible and will allow model independent extraction of the reaction amplitude. An overview of the experiment and its current status is presented.

Eugene Pasyuk; for the CLAS Collaboration

2009-06-23

347

Scattering properties of natural snow and frost - Comparison with icy satellite photometry  

NASA Technical Reports Server (NTRS)

The Hapke (1986) equation is presently fit to ascertain the single-scattering albedo of the icy satellites of Uranus and Neptune and the one-term Henyey-Greenstein particle-phase function g for each of the Middleton and Mungall (1952) goniophotometric data samples. There emerge both very high single-scattering albedos and strongly forward-scattering particle phase functions; while these are in keeping with Mie theory-based theoretical considerations, they contrast with the observed backscattering behavior of icy satellites. It is suggested the icy satellite frost grains are aggregated into particles of complex texture, which produce the unusual backscattering behavior.

Verbiscer, Anne J.; Veverka, Joseph

1990-01-01

348

Determination of E and G Observables in n Photoproduction on the CLAS Frozen Spin Target (FROST)  

SciTech Connect

Polarization observables are vital for disentangling overlapping resonances in the baryon spectrum. Extensive data have been collected at Jefferson Lab in Hall B with circularly and linearly polarized tagged photon beam incident on longitudinally polarized protons provided by the Frozen Spin Target (FROST). The focus of the described work is on ? photoproduction, which acts as an "isospin filter", isolating the N*(I = 1/2) resonances. Preliminary results for the double-polarization observables E and G are presented. There are currently no data on these in the world database for ? photoproduction.

Senderovich, Igor [University of Connecticut, Storrs, CT (United States); Morrison, Brian T. [Arizona State University, Tempe, AZ (United States); Dugger, Michael R. [Arizona State University, Tempe, AZ (United States); Ritchie, Barry G. [Arizona State University, Tempe, AZ (United States); Tucker, Ross J. [Arizona State University, Tempe, AZ (United States)

2014-01-01

349

Scattering properties of natural snow and frost - Comparison with icy satellite photometry  

SciTech Connect

The Hapke (1986) equation is presently fit to ascertain the single-scattering albedo of the icy satellites of Uranus and Neptune and the one-term Henyey-Greenstein particle-phase function g for each of the Middleton and Mungall (1952) goniophotometric data samples. There emerge both very high single-scattering albedos and strongly forward-scattering particle phase functions; while these are in keeping with Mie theory-based theoretical considerations, they contrast with the observed backscattering behavior of icy satellites. It is suggested the icy satellite frost grains are aggregated into particles of complex texture, which produce the unusual backscattering behavior. 26 refs.

Verbiscer, A.J.; Veverka, J. (Cornell Univ., Ithaca, NY (USA))

1990-12-01

350

Free convection oxygen vaporizer heat transfer as a function of relative humidity and frost buildup  

NASA Astrophysics Data System (ADS)

A series of free convection heat transfer tests were made to simulate oxygen vaporizer fintube performance as a function of controlled levels of relative humidity. Test runs were made for relative humidity values set at 20, 40, 60 and 80%. Each test started with a bare fintube and continued until approximately steady state conditions were reached. Frost buildup on the aluminum fintubes was tracked by a continuous video of each test. Plots of heat transfer rates measured in these tests provide data for designing the two-phase portions of liquid oxygen vaporizers for varying ambient humidity conditions.

McIntosh, G. E.; Haaf, K. L.; Moyers, J. A.

2014-01-01

351

Numerical Analysis of the Channel Wheel Fresh Air Ventilator Under Frosting Conditions  

E-print Network

ICEBO2006, Shenzhen, China HVAC Technologies for Energy Efficiency Vol.IV-4-4 Numerical Analysis of the Channel Wheel Fresh Air Ventilator Under Frosting Conditions Bo Gao Zhongcheng Dong Zhigang Cheng Ercang Luo... 60W 270m3/h ? 69? 20kg G3 36 Aluminum 720mm 200mm ICEBO2006, Shenzhen, China HVAC Technologies for Energy Efficiency Vol.IV-4-4 side (Wm K ); 2? 1? 2? ?the heat transfer coefficient of outdoor fresh air side (Wm K ). 2? 1? The general...

Gao, B.; Dong, Z.; Cheng, Z.; Luo, E.

2006-01-01

352

Layers and Layers  

NSDL National Science Digital Library

This lesson has students create their own rock layers by slowly adding and observing how different types of sediment interact when layered upon each other. This lesson is meant to illustrate how we can use these layers to discover the relative age of an object found in that layer by utilizing the Law of Superposition.

Cheri Tremarco

2011-10-07

353

Combined effects of copper, desiccation, and frost on the viability of earthworm cocoons  

SciTech Connect

The effects of heavy metal pollution on earthworms have been extensively studied, but no studies have examined how earthworms react if they are simultaneously exposed to metal pollution and climatic stress. This question has been addressed in a laboratory study where cocoons of Aporrectodea caliginosa and Dendrobaena octaedra were initially exposed to copper in aqueous solutions of copper chloride and thereafter exposed to realistic degrees of either desiccation or frost. Earthworm embryos absorbed copper in amounts comparable to concentrations found in various tissues of earthworms from metal-polluted soils. Desiccation and copper exposure in combination had synergistic effects on survival rates for both species. For example, at full saturation, the NOEC (the highest tested concentration with no statistically significant effect) for copper of A. caliginosa was 12 mg/L, whereas at 97% relative humidity it was only 6 mg/L. Frost and copper exposure in combination also showed synergistic effects in some experiments. No cocoons of A. caliginosa exposed to 20 mg copper/L were viable after exposure to {minus}3 C but at 0 C viability was as high as 95%. The same tendency was seen in D. octaedra but not as clearly as in A/. caliginosa. A change of the environmental conditions (moisture, temperature) to increasing severity caused a shift in the statistically derived NOEC toward lower critical values of copper. The involvement of combination effects in ecotoxicological tests could therefore improve risk assessment of soil-polluting compounds.

Holmstrup, M. [National Environmental Research Inst., Silkeborg (Denmark). Dept. of Terrestrial Ecology; Petersen, B.F. [National Environmental Research Inst., Silkeborg (Denmark). Dept. of Terrestrial Ecology]|[Univ. of Aarhus (Denmark); Larsen, M.M. [National Environmental Research Inst., Roskilde (Denmark). Dept. of Marine Ecology and Microbiology

1998-01-01

354

[Frost-resistance of subtropical evergreen woody plants: an evaluation based on plant functional traits].  

PubMed

Evaluating the frost-resistance of evergreen woody plants is of significance in guiding the species selection in forest management in subtropical region. In this paper, an investigation was made on the functional traits (including specific leaf area, stem wood density, leaf area, leaf dry matter content, leaf relative electrical conductance, and twig wood density) of 64 common evergreen broad-leaved and coniferous woody plant species in the Ningbo region of Zhejiang Province, East China, after a severe snowstorm in early 2008, aimed to select the evergreen woody plants with high ability of freeze-tolerance, and to establish a related evaluation system. By using a hierarchy analysis approach, the weight values of the functional traits of each species were determined, and an index system for evaluating the plants tolerance ability against freeze and mechanical damage was established. Based on this system, 23 evergreen plant species with high tolerance ability against freeze and mechanical damage, such as Cyclobalanopsis gilva, Cyclobalanopsis nubium, Neolitsea aurata, and Vacciniuim mandarinorum, were selected. In the meantime, on the basis of the ordering with each of the functional traits, the ordering of the tolerance ability of the 64 plant species against freeze and mechanical damage was made, and a list for the frost-resistance ability of the subtropical evergreen woody plant species in Ningbo region was constituted. PMID:23479868

Xu, Yi-Lu; Yang, Xiao-Dong; Xu, Yue; Xie, Yi-Ming; Wang, Liang-Yan; Yan, En-Rong

2012-12-01

355

Correlation formulas for the frost thickness and heat transfer coefficient on a cylinder in humid air cross flow  

SciTech Connect

This paper reports on results of an experimental investigation where the emphasis was placed on obtaining empirical correlations for the frost thickness-time history and the heat transfer coefficient-time history for a cylinder in humid air cross flow. The facility employed for the investigation consisted of a low velocity wind tunnel comprised of a rectangular test section, a transition section and a honeycomb placed at the tunnel entrance. An external refrigerator was used to cool an antifreeze solution having a mixture of 90% methanol and 10% ethylene glycol. Measured parameters included, among other things, the heat transfer coefficient as well as the frost thickness.

Sengupta, S.; Sherif, S.A. [Univ. of Florida, Gainesville, FL (United States). Dept. of Mechanical Engineering; Wong, K.V. [Univ. of Miami, Coral Gables, FL (United States). Dept. of Mechanical Engineering

1995-12-31

356

Robert Frost's Chicken Feathers and Other Lectures from the 1968 Augustana College NDEA English Institute. Augustana College Press Monograph Series No. 1.  

ERIC Educational Resources Information Center

The four lectures in this publication were composed with the common concern for making the study of high school English more effective and more delightful. Papers are (1) "Robert Frost's Chicken Feathers" by C. W. Geyer (discusses the influence of oral folklore and humor on Frost's poetry); (2) "Nature in Literature" by Gerhard T. Alexis; (3)…

Huseboe, Arthur R., Ed.

357

Frost and Harvest Date Effects on Yield and Nutritive Value of Silage Maize (Zea mays L.) in a Short-Season Environment  

Microsoft Academic Search

The danger of frost damage before harvest is an ever present risk to corn (Zea mays L.) growers in Newfoundland, Canada. The objective of this study was to investigate the effects of frost and harvest date on dry matter (DM) yield and nutritive value of silage corn. In 2000, 2001 and 2002, the DM yield and nutritive value of Pioneer(r)

A. B. Kwabiah

2005-01-01

358

Effect of snow and soil frost melting on the concentrations of suspended solids and phosphorus in two rural watersheds in Western Finland  

Microsoft Academic Search

Hydrological processes are known to have a considerable effect on nutrient transport from agricultural land to watercourses. In cold temperate regions peak discharges are caused not only by storm conditions but also by melting of snow and frost. The objective of this work was to investigate the effects of snow and frost melt on concentrations of phosphorus and suspended solids.

Seppo Rekolainen

1989-01-01

359

Enceladus' CO2 Frost comes from Near-Surface Gas Pockets  

NASA Astrophysics Data System (ADS)

CO2 frost has been detected on the surface of Enceladus [1]. It was noted by Brown et al. [1] that the frost deposits are not likely permanent and that an active replenishment processes for the gas might be necessary. We suggest that the CO2 that forms the frost originates in shallow gas pockets below the surface. These pockets are a consequence of the ocean water circulation hypothesis [2]. They differ from the plume chambers [3] and are a previously unrecognized structure in the near-surface ice. Enceladus’ oceanic circulation is driven by gas bubbles that make seawater buoyant and bring up water, chemicals, and heat from the depths of a warm ocean [2]. The ocean water ascends through the icy crust and, near the surface, it spreads out laterally beneath a relatively thin ice cap, following the pattern of the thermal anomalies identified in Cassini data [4,5]. Topographic recesses on the bottom of the ice cap act as pockets that collect gas. As the ocean water flows horizontally, the gas bubbles in it continue to rise vertically. Rising bubbles reach the pockets and, over time, pop and release gas. The gas pockets can be ruptured by the regular tidally-controlled fissuring of ice in the South Polar Region (Hurford et al. [6]), forming rifts. If a rift reaches a gas pocket, CO2 gas may escape to the surface. The tortuosity and other properties along the escape route will determine if the gas vents as a seep or a jet. If enough gas is vented to form a cloud, some of the gas will freeze on the surface. This work was performed at the Jet Propulsion Laboratory, California Institute of Technology, under contract to NASA. 2006. [2] Matson D. L. et al., Icarus 221, 53-62, 2012. (also see Matson et al. LPS 44 Abstract 1371, 2013). [3] Schmidt J. et al., Nature 451, 685-688, 2008. [4] Spencer J. R. et al., Science 311, 1401-1405, 2006. [5] Howett C. et al., JGR 116, E03003, 2011. [6] Hurford T. A. et al., Nature 447, 292-294, 2007.

Matson, Dennis L.; Johnson, Torrence; Castillo-Rogez, Julie; Davies, Ashley; Lunine, Jonathan; Radebaugh, Jani

360

Frost drought in conifers at the alpine timberline: xylem dysfunction and adaptations.  

PubMed

Drought stress can cause xylem embolism in trees when the water potential (psi) in the xylem falls below specific vulnerability thresholds. At the alpine timberline, frost drought is known to cause excessive winter embolism unless xylem vulnerability or transpiration is sufficiently reduced to avoid critical psi. We compared annual courses of psi and embolism in Picea abies, Pinus cembra, Pinus mugo, Larix decidua, and Juniperus communis growing at the timberline vs. low altitude. In addition, vulnerability properties and related anatomical parameters as well as wood density (D(t)) and wall reinforcement (wall thickness related to conduit diameter) were studied. This allowed an estimate of stress intensities as well as a detection of adaptations that reduce embolism formation. At the alpine timberline, psi was lowest during winter with corresponding embolism rates of up to 100% in three of the conifers studied. Only Pinus cembra and Larix decidua avoided winter embolism due to moderate psi. Minor embolism was observed at low altitude where the water potentials of all species remained within a narrow range throughout the year. Within species, differences in psi50 (psi at 50% loss of conductivity) at high vs. low altitude were less than 1 MPa. In Picea abies and Pinus cembra, psi50 was more negative at the timberline while, in the other conifer species, psi50 was more negative at low altitude. Juniperus communis exhibited the lowest (-6.4 +/- 0.04 MPa; mean +/- SE) and Pinus mugo the highest psi50 (-3.34 +/- 0.03 MPa). In some cases, D(t) and tracheid wall reinforcement were higher than in previously established relationships of these parameters with psi50, possibly because of mechanical demands associated with the specific growing conditions. Conifers growing at the alpine timberline were exposed to higher drought stress intensities than individuals at low altitude. Frost drought during winter caused high embolism rates which were probably amplified by freeze-thaw stress. Although frost drought had a large effect on plant water transport, adaptations in hydraulic safety and related anatomical parameters were observed in only a few of the conifer species studied. PMID:17249241

Mayr, Stefan; Hacke, Uwe; Schmid, Peter; Schwienbacher, Franziska; Gruber, Andreas

2006-12-01

361

Patterns of genetic variation in mountain hemlock ( Tsuga mertensiana (Bong.) Carr.) with respect to height growth and frost hardiness  

Microsoft Academic Search

Genetic structure (variance among and within populations) and geographic pattern of variations in growth and frost hardiness of mountain hemlock (Tsuga mertensiana (Bong.) Carr.) populations from coastal British Columbia (BC) were examined. Populations fell into two main groups — south coast (16 sources) and north coast (two sources). Height growth of greenhouse grown seedlings was measured during the first growing

Andy Benowicz; Sylvia L’Hirondelle; Yousry A El-Kassaby

2001-01-01

362

Dimensionality and Typology of Perfectionism: The Use of the Frost Multidimensional Perfectionism Scale with Chinese Gifted Students in Hong Kong  

ERIC Educational Resources Information Center

This study investigated the dimensionality and typology of perfectionism based on the Frost Multidimensional Perfectionism Scale with a sample of 380 Chinese gifted students in Hong Kong. Confirmatory factor analyses supported a five-dimensional model that includes constructs of personal standards, parental expectations, parental criticism,…

Chan, David W.

2009-01-01

363

Psychometric Properties of the Frost Multidimensional Perfectionism Scale with Australian Adolescent Girls: Clarification of Multidimensionality and Perfectionist Typology  

ERIC Educational Resources Information Center

The psychometric properties of the Frost, Marten, Lahart, and Rosenblate Multidimensional Perfectionism Scale (1990) are investigated to determine its usefulness as a measurement of perfectionism with Australian secondary school girls and to find empirical support for the existence of both healthy and unhealthy types of perfectionist students.…

Hawkins, Colleen C.; Watt, Helen M. G.; Sinclair, Kenneth E.

2006-01-01

364

Predicting spring phenology and frost damage risk of Betula spp. under climatic warming: a comparison of two models  

Microsoft Academic Search

Summary Timing of bud burst and frost damage risk for leaves of Betula spp. in response to climatic warming in Fin- land was examined with two models. In the first model, onto- genetic development in spring was triggered by an accumula- tion of chilling temperatures. The second model assumed an additional signal from the light climate. The two models gave

TAPIO LINKOSALO; TIMOTHY R. CARTER; RISTO HÄKKINEN; PERTTI HARI

365

A Taxonomy of Sensor Network Architectures D.T. Fokum, V.S. Frost, P. Mani, G.J. Minden,  

E-print Network

A Taxonomy of Sensor Network Architectures D.T. Fokum, V.S. Frost, P. Mani, G.J. Minden, J.B. Evans Laboratory TechnicalReport The University of Kansas #12;A Taxonomy of Sensor Network Architectures D.T. Fokum share several invariants. Key words: Sensor Networks; Taxonomy; Sensor network architecture; Invariant

Kansas, University of

366

Experimental Research of Air Source Heat Pump Frosting and Defrosting in a Double Stage-Coupling Heat Pump  

E-print Network

. The most common method of air source heat pump frost removal is reverse-cycle defrost. During the defrosting operation, the heat pump runs in the cooling mode. The defrost process is accomplished by reversing the normal heating mode. In this paper...

Wang, Z.; Gu, J.; Lu, Z.

2006-01-01

367

Polytrichum Strictum as a Solution to Frost Heaving in Disturbed Ecosystems: A Case Study with Milled Peatlands  

Microsoft Academic Search

Substrate instability is a common problem in many dis- turbed ecosystems. In the case of milled harvested peatlands, the pioneer moss Polytrichum strictum is commonly found; it is well adapted to tolerate the harsh microclimatic conditions and peat instability of these sites. A field experiment was used to determine the effective- ness of P. strictum against frost heaving, a major

Elisabeth V. G. Groeneveld; Line Rochefort

2005-01-01

368

Intercomparisons of Stratospheric Water Vapor Sensors: FLASH-B and NOAA/CMDL Frost-Point Hygrometer  

E-print Network

). The comparison identified some instrumental issues, such as a low mirror-temperature calibration correctionIntercomparisons of Stratospheric Water Vapor Sensors: FLASH-B and NOAA/CMDL Frost-Point Hygrometer payload that was launched multiple times at Sodankylä, Finland. The comparison shows agreement well within

Vömel, Holger

369

Mars south polar spring and summer temperatures - A residual CO2 frost  

NASA Technical Reports Server (NTRS)

Viking infrared thermal mapper (IRTM) energy measurements over the Mars south polar cap throughout the Martian spring and summer revealed complex spatial, spectral, and temporal variations. High albedos did not directly correspond with low temperatures, and as the cap shrank to its residual position, it maintained large differences in brightness temperature between the four IRTM surface-sensing bands at 7, 9, 11, and 20 microns. The late summer infrared spectral pattern can be matched by a surface consisting of CO2 frost with 20 micron emissivity of 0.8 and about 6% dark, warm soil under a dusty atmosphere of moderate infrared opacity and spectral properties similar to those measured for the Martian global dust storms. Low temperature, the absence of appreciable water vapor in the south polar atmosphere, and the absence of surface warming expected if H2O were to become exposed, all imply that the residual south polar cap was covered by solid CO2.

Kieffer, H. H.

1979-01-01

370

Surface temperatures and retention of H2O frost on Ganymede and Callisto  

NASA Technical Reports Server (NTRS)

Surface temperatures and ice evaporation rates are calculated for Ganymede and Callisto as functions of latitude, time of day, and albedo, according to a model that uses surface thermal properties determined by eclipse radiometry and albedos determined from photometrically decalibrated Voyager images. The difference in temperature between Ganymede and Callisto is not great enough to account for the lack of bright polar caps on Callisto, which seems instead to reflect a real deficiency in the amount of available water frost relative to Ganymede. The temperature difference between Ganymede's grooved and cratered terrains also cannot account for the high concentration of bright ray craters in the former, suggesting that an internal geologic process has enriched the grooved terrain in ice content relative to the cratered terrain.

Squyres, S. W.

1980-01-01

371

Elevated mercury measured in snow and frost flowers near Arctic sea ice leads  

NASA Astrophysics Data System (ADS)

Elevated mercury concentrations have been reported in arctic coastal snow far from emission sources. The mercury is deposited during mercury depletion events (MDEs), a set of photochemical atmospheric reactions involving reactive halogens. The highest mercury concentrations are clustered near the coast, leading to speculation that sea ice or sea ice leads play a role in MDEs. The nature of this connection is not fully understood. We report mercury concentrations up to 820 ng/L in snow and frost flowers along sea ice leads near Barrow, Alaska. These concentrations are nine times higher than values from nearby coastal snow and are almost half of the mercury maximum contaminant level in United States drinking water. The high values were found only near leads that had convective plumes above open water suggesting that the same processes that produce a supersaturated environment for water vapor near sea ice leads may be instrumental in mercury deposition.

Douglas, T. A.; Sturm, M.; Simpson, W. R.; Brooks, S.; Lindberg, S. E.; Perovich, D. K.

2005-02-01

372

Climatic significance of the bristlecone pine latewood frost-ring record at Almagre Mountain, Colorado, U.S.A.  

SciTech Connect

From 1900 to 1993, latewood frost rings occurred in 1903, 1912, 1941, 1961, and 1965 in 10 to 21% of the sampled bristlecone pines at Almagre Mountain, Colorado. In early to mid September in each of those years, a severe outbreak of unseasonably cold air from higher latitudes produced a memorable or historic late-summer snowstorm in the western United States. Record subfreezing temperatures during these snowstorms probably caused the latewood frost rings, shortened (by about 1 mo in 1912) already colder than normal growing seasons, and caused crop damage in parts of the Western United States. Latewood frost rings recorded in relatively high percentages of the sampled trees were probably caused by multiple severe outbreaks of unseasonably cold air from higher latitudes that occurred from early September to mid-September. Analyses of 1900-1992 temperature data for two widely separated Colorado stations, Fort Collins and Colorado Springs, show that average summer (June-September) temperatures during latewood frost-ring years in this century were 1.5 and 2.0{degrees}C cooler than normal, respectively. Mountain snowpack probably persisted through these cool summers and was subsequently buried by the earlier than normal snowfall in September. Latewood frost-ring, ring-width, historical, and other data suggest that severe to cataclysmic volcanic eruptions from 1812 to 1835 triggered (1) an extended period of climatic cooling from as early as 1816 or 1817 through the early 1850s in the Southern Rocky Mountains, (2) catastrophic winters in Colorado and Wyoming in 1842-43 and 1844 45, and in the Great Salt Lake Basin in 1836-37, that caused large-scale destruction of bison and other large plains animals, and (3) Little Ice Age alpine glacial advances in about 1850-60 in the western United States.

Brunstein, F.C. [Geological Survey, Denver, CO (United States)

1996-02-01

373

Climatic significance of the bristlecone pine latewood frost-ring record at Almagre Mountain, Colorado, U.S.A.  

USGS Publications Warehouse

From 1900 to 1993, latewood frost rings occurred in 1903, 1912, 1941, 1961, and 1965 in 10 to 21% of the sampled bristlecone pines at Almagre Mountain, Colorado. In early to mid September in each of those years, a severe outbreak of unseasonably cold air from higher latitudes produced a memorable or historic late-summer snowstorm in the western United States. Record subfreezing temperatures during these snowstorms probably caused the latewood frost rings, shortened (by about 1 mo in 1912) already colder than normal growing seasons, and caused crop damage in parts of the Western United States. Latewood frost rings recorded in relatively high percentages of the sampled trees (such as the 1805 event in 61% of sampled trees) were probably caused by multiple severe outbreaks of unseasonably cold air from higher latitudes that occurred from early September (possibly as early as mid- or late August) to mid-September. Analyses of 1900-1992 temperature data for two widely separated Colorado stations, Fort Collins and Colorado Springs, show that average summer (June-September) temperatures during latewood frost-ring years in this century were 1.5 and 2.0??C cooler than normal, respectively. Mountain snowpack probably persisted through these cool summers and was subsequently buried by the earlier than normal snowfall in September. Latewood frost-ring, ring-width, historical, and other data suggest that severe to cataclysmic volcanic eruptions from 1812 to 1835 triggered (1) an extended period of climatic cooling from as early as 1816 or 1817 through the early 1850s in the Southern Rocky Mountains, (2) catastrophic winters in Colorado and Wyoming in 1842-43 and 1844-45, and in the Great Salt Lake Basin in 1836-37, that caused large-scale destruction of bison and other large plains animals, and (3) Little Ice Age alpine glacial advances in about 1850-60 in the western United States.

Craig, Brunstein F.

1996-01-01

374

Is Shade Beneficial for Mediterranean Shrubs Experiencing Periods of Extreme Drought and Late-winter Frosts?  

PubMed Central

Background and Aims Plants are naturally exposed to multiple, frequently interactive stress factors, most of which are becoming more severe due to global change. Established plants have been reported to facilitate the establishment of juvenile plants, but net effects of plant–plant interactions are difficult to assess due to complex interactions among environmental factors. An investigation was carried out in order to determine how two dominant evergreen shrubs (Quercus ilex and Arctostaphylos uva-ursi) co-occurring in continental, Mediterranean habitats respond to multiple abiotic stresses and whether the shaded understorey conditions ameliorate the negative effects of drought and winter frosts on the physiology of leaves. Methods Microclimate and ecophysiology of sun and shade plants were studied at a continental plateau in central Spain during 2004–2005, with 2005 being one of the driest and hottest years on record; several late-winter frosts also occurred in 2005. Key Results Daytime air temperature and vapour pressure deficit were lower in the shade than in the sun, but soil moisture was also lower in the shade during the spring and summer of 2005, and night-time temperatures were higher in the shade. Water potential, photochemical efficiency, light-saturated photosynthesis, stomatal conductance and leaf 13C composition differed between sun and shade individuals throughout the seasons, but differences were species specific. Shade was beneficial for leaf-level physiology in Q. ilex during winter, detrimental during spring for both species, and of little consequence in summer. Conclusions The results suggest that beneficial effects of shade can be eclipsed by reduced soil moisture during dry years, which are expected to be more frequent in the most likely climate change scenarios for the Mediterranean region. PMID:18819947

Valladares, Fernando; Zaragoza-Castells, Joana; Sánchez-Gómez, David; Matesanz, Silvia; Alonso, Beatriz; Portsmuth, Angelika; Delgado, Antonio; Atkin, Owen K.

2008-01-01

375

Chilling and frost tolerance in Miscanthus and Saccharum genotypes bred for cool temperate climates.  

PubMed

Miscanthus hybrids are leading candidates for bioenergy feedstocks in mid to high latitudes of North America and Eurasia, due to high productivity associated with the C4 photosynthetic pathway and their tolerance of cooler conditions. However, as C4 plants, they may lack tolerance of chilling conditions (0-10 °C) and frost, particularly when compared with candidate C3 crops at high latitudes. In higher latitudes, cold tolerance is particularly important if the feedstock is to utilize fully the long, early-season days of May and June. Here, leaf gas exchange and fluorescence are used to assess chilling tolerance of photosynthesis in five Miscanthus hybrids bred for cold tolerance, a complex Saccharum hybrid (energycane), and an upland sugarcane variety with some chilling tolerance. The chilling treatment consisted of transferring warm-grown plants (25/20 °C day/night growth temperatures) to chilling (12/5 °C) conditions for 1 week, followed by assessing recovery after return to warm temperatures. Chilling tolerance was also evaluated in outdoor, spring-grown Miscanthus genotypes before and after a cold front that was punctuated by a frost event. Miscanthus×giganteus was found to be the most chilling-tolerant genotype based on its ability to maintain a high net CO2 assimilation rate (A) during chilling, and recover A to a greater degree following a return to warm conditions. This was associated with increasing its capacity for short-term dark-reversible photoprotective processes (?REG) and the proportion of open photosystem II reaction centres (qL) while minimizing photoinactivation (?NF). Similarly, in the field, M.×giganteus exhibited a significantly greater A and pre-dawn F v/F m after the cold front compared with the other chilling-sensitive Miscanthus hybrids. PMID:24642848

Friesen, Patrick C; Peixoto, Murilo M; Busch, Florian A; Johnson, Daniel C; Sage, Rowan F

2014-07-01

376

Improvement of the interface quality during thermal oxidation of Al{sub 0.98}Ga{sub 0.02}As layers due to the presence of low-temperature-grown GaAs  

SciTech Connect

The role of a low-temperature-grown GaAs (LT GaAs) layer on the lateral oxidation of an Al{sub 0.98}Ga{sub 0.02}As/GaAs layer structure has been studied by transmission electron microscopy. Results show that structures incorporating LT GaAs develop better quality oxide/GaAs interfaces compared to reference samples without LT GaAs. While the latter have As accumulation in the vicinity of these interfaces, the structures with LT layers display sharper oxide-GaAs interfaces with a reduced concentration of As. These results are explained in terms of the high Ga vacancy concentration in the LT GaAs and the possible influence of those vacancies in enhancing As diffusion away from the oxide-semiconductor interface. (c) 2000 American Institute of Physics.

Ferrer, J. C. [Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)] [Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Liliental-Weber, Z. [Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)] [Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Reese, H. [Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106 (United States)] [Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106 (United States); Chiu, Y. J. [Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106 (United States)] [Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106 (United States); Hu, E. [Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106 (United States)] [Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106 (United States)

2000-07-10

377

Improvement of the interface quality during thermal oxidation of Al0.98Ga0.02As layers due to the presence of low-temperature-grown GaAs  

SciTech Connect

The role of a low-temperature-grown GaAs (LT GaAs) layer on the lateral oxidation of an Al0.98Ga0.02As/GaAs layer structure has been studied by transmission electron microscopy. Results show that structures incorporating LT GaAs develop better quality oxide/GaAs interfaces compared to reference samples without LT GaAs. While the latter have As accumulation in the vicinity of these interfaces, the structures with LT layers display sharper oxide-GaAs interfaces with a reduced concentration of As. These results are explained in terms of the high Ga vacancy concentration in the LT GaAs and the possible influence of those vacancies in enhancing As diffusion away from the oxide-semiconductor interface.

Ferrer, J.C.; Liliental-Weber, Z.; Reese, H.; Chiu, Y.J.; Hu, E.

2000-06-06

378

EVIDENCE FOR FRESH FROST LAYER ON THE BARE NUCLEUS OF COMET HALE-BOPP AT 32 AU DISTANCE  

SciTech Connect

Here, we report that the activity of comet Hale-Bopp ceased between late 2007 and 2009 March, at about 28 AU distance from the Sun. At that time, the comet resided at a distance from the Sun that exceeded the freeze-out distance of regular comets by an order of magnitude. A Herschel Space Observatory PACS scan was taken in mid-2010, in the already inactive state of the nucleus. The albedo has been found to be surprisingly large (8.1% {+-} 0.9%), which exceeds the value known for any other comets. With re-reduction of archive Hubble Space Telescope images from 1995 and 1996, we confirm that the pre-perihelion albedo resembled that of an ordinary comet and was smaller by a factor of two than the post-activity albedo. Our further observations with the Very Large Telescope also confirmed that the albedo increased significantly by the end of the activity. We explain these observations by proposing gravitational redeposition of icy grains toward the end of the activity. This is plausible for such a massive body in a cold environment, where gas velocity is lowered to the range of the escape velocity. These observations also show that giant comets are not just the upscaled versions of the comets we know but can be affected by processes that are yet to be fully identified.

Szabo, Gyula M.; Kiss, Laszlo L.; Pal, Andras; Kiss, Csaba; Sarneczky, Krisztian [MTA CSFK, Konkoly Observatory, Konkoly Thege Miklos ut 15-17, H-1121 Budapest (Hungary); Juhasz, Attila; Hogerheijde, Michiel R. [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands)

2012-12-10

379

Laboratory studies of charged particle erosion of SO2 ice and applications to the frosts of Io  

NASA Technical Reports Server (NTRS)

The removal and/or redistribution of SO2 frosts on the surface of the first Galilean satellite, Io, can occur through the erosion of these frosts by the magnetosphere particle environment of the satellite. The energy, species, and temperature dependence of the erosion rates of SO2 ice films by charged particles have been studied in laboratory experiments. Rutherford backscattering and thin film techniques are used in the experiments. The ice temperature is varied between about 10 K and the sublimation temperature. The erosion rates are found to have a temperature-independent and a temperature-dependent regime and to be much greater, for 10-2000 keV ions, than those predicted by the usual sputtering process. The laboratory results are used together with measured magnetosphere particle fluxes in the vicinity of Io to estimate the erosion rates of SO2 ice films from the satellite and implications therefrom on an SO2 atmosphere on Io.

Lanzerotti, L. J.; Brown, W. L.; Augustyniak, W. M.; Johnson, R. E.; Armstrong, T. P.

1982-01-01

380

Atlas of reflectance spectra of terrestrial, lunar, and meteoritic powders and frosts from 92 to 1800 nm  

NASA Technical Reports Server (NTRS)

The spectra of samples of several powder and frost materials are presented to serve in a reference database for future far-UV scans of solar system bodies. The spectra cover in the 92-1800 nm wavelengths, i.e., wavenumbers 110,000-5600/cm and photon energies from 13.5-1.5 eV. Preparation procedures for the particulates are delineated. The survey includes feldspars, orthopyroxenes, clinopyroxenes, olivines, assorted minerals, achondrites, carbonaceous chondrites and ordinary chondrites, lunar soils and rocks. Frosts of H2O, CO2, NH3 and SO2 gases were also examined. The data are expected to aid in obtaining spectral matches for asteroids and meteoroids when far-UV telescopy of solar system bodies is performed.

Wagner, Jeffrey K.; Hapke, Bruce W.; Wells, Eddie N.

1987-01-01

381

The design, construction, and instrumentation of a chamber to study heat, mass, and momentum transfer from humid air to metal under conditions of frosting and free convection  

E-print Network

THE DESIGN? CONSTRUCTION? AND INSTRUMENTATION OF A CEAMSER TO STUDY HEAT, MASS? AND MOSNTUM TRANSFER FROM HUMID AIR TO METAL UNDER CONDITIONS OF FROSTING AND FREE CONVECTION A Thesis By James P. Hutchison Submitted to the Graduate School..., AND MOMENTUM TRANSFER FROM HUMID AIR TO METAL UNDER CONDITIONS OF FROSTING AND FREE CONVECTION A Thesis By James P. Hutchison Approved as to Style and Content: Chairman of Committee Head of Departm t + gkA4; August 1961 ACKNOWLEDGEMENT S The writer...

Hutchison, James P

1961-01-01

382

Local adaptations to frost in marginal and central populations of the dominant forest tree Fagus sylvatica L. as affected by temperature and extreme drought in common garden experiments  

PubMed Central

Local adaptations to environmental conditions are of high ecological importance as they determine distribution ranges and likely affect species responses to climate change. Increased environmental stress (warming, extreme drought) due to climate change in combination with decreased genetic mixing due to isolation may lead to stronger local adaptations of geographically marginal than central populations. We experimentally observed local adaptations of three marginal and four central populations of Fagus sylvaticaL., the dominant native forest tree, to frost over winter and in spring (late frost). We determined frost hardiness of buds and roots by the relative electrolyte leakage in two common garden experiments. The experiment at the cold site included a continuous warming treatment; the experiment at the warm site included a preceding summer drought manipulation. In both experiments, we found evidence for local adaptation to frost, with stronger signs of local adaptation in marginal populations. Winter frost killed many of the potted individuals at the cold site, with higher survival in the warming treatment and in those populations originating from colder environments. However, we found no difference in winter frost tolerance of buds among populations, implying that bud survival was not the main cue for mortality. Bud late frost tolerance in April differed between populations at the warm site, mainly because of phenological differences in bud break. Increased spring frost tolerance of plants which had experienced drought stress in the preceding summer could also be explained by shifts in phenology. Stronger local adaptations to climate in geographically marginal than central populations imply the potential for adaptation to climate at range edges. In times of climate change, however, it needs to be tested whether locally adapted populations at range margins can successfully adapt further to changing conditions. PMID:25035801

Kreyling, Juergen; Buhk, Constanze; Backhaus, Sabrina; Hallinger, Martin; Huber, Gerhard; Huber, Lukas; Jentsch, Anke; Konnert, Monika; Thiel, Daniel; Wilmking, Martin; Beierkuhnlein, Carl

2014-01-01

383

North Polar Layered Deposits in Summer  

NASA Technical Reports Server (NTRS)

The High Resolution Imaging Science Experiment (HiRISE) on NASA's Mars Reconnaissance Orbiter acquired this image during its first day of test imaging from the spacecraft's low-altitude mapping orbit, Sept. 29, 2006.

This image of Mars' north polar layered deposits was taken during the summer season (solar longitude of 113.6 degrees), when carbon dioxide frost had evaporated from the surface. The bright spots seen here are most likely patches of water frost, but the location of the frost patches does not appear to be controlled by topography. Layers are visible at the bottom of the image, mostly due to difference in slope between them. The variations in slope are probably caused by differences in the physical properties of the layers. Thinner layers that have previously been observed in these deposits are visible, and may represent annual deposition of water ice and dust that is thought to form the polar layered deposits. These deposits are thought to record global climate variations on Mars, similar to ice ages on Earth. HiRISE images such as this should allow Mars' climate record to be inferred and compared with climate changes on Earth.

Image TRA_000825_2665 was taken by the High Resolution Imaging Science Experiment (HiRISE) camera onboard the Mars Reconnaissance Orbiter spacecraft on September 29, 2006. Shown here is the full image, centered at 86.5 degree latitude, 172.0 degrees east longitude. The image is oriented such that north is to the top. The range to the target site was 298.9 kilometers (186.8 miles). At this distance the image scale is 59.8 centimeters (23.5 inches) per pixel (with two-by-two binning} so objects about 1.79 meters (70 inches) across are resolved. In total the original image was 12.2 kilometers 7.58 mile; 10024 pixels) wide and 6.1 kilometers (3.79 miles; 5000 pixels) long. The image was taken at a local Mars time of 3:30 PM and the scene is illuminated from the southwest with a solar incidence angle of 63.5 degrees, thus the sun was about 26.5 degrees above the horizon.

NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems is the prime contractor for the project and built the spacecraft. The HiRISE camera was built by Ball Aerospace Corporation and is operated by the University of Arizona.

2006-01-01

384

Heritable improvement of frost tolerance in winter wheat by in vitro-selection of hydroxyproline-resistant proline overproducing mutants  

Microsoft Academic Search

In a previous study (Dörffling et al., J. Plant Physiol. 142, 222–225, 1993) in vitro-selection and regeneration of hydroxyproline (Hyp)-resistant lines of winter wheat (Triticum aestivum cv. Jo 3063) with increased frost tolerance and increased proline contents was reported. In this study the heritability of these traits was investigated. The F 1progenies derived from the pollination of regenerated plants with

K. Dörffling; H. Dörffling; G. Lesselich; E. Luck; C. Zimmermann; G. Melz; H. U. Jürgens

1997-01-01

385

Development of Fractal Ultra-Hydrophobic Coating Films to Prevent Water Vapor Dewing and to Delay Frosting  

NASA Astrophysics Data System (ADS)

Superhydrophobic films fabricated on copper and aluminum surfaces have potential applications to solve water condensation and frosting problems on chilled ceiling system. The rough surfaces of copper foils obtained by solution immersion method exhibit the existence of fractal structures. The hydrophobicity of copper surfaces is enhanced with fractal structures. The relationship between contact angles (CAs) and the fractal dimensions (FDs) for surface roughness of Cu samples with different etching time is investigated. Moisture condensation and frosting experiments on the two kinds of surfaces are conducted in natural environment under different chilling temperatures. During condensation, micro water condensate droplets drift down the surface like dust floating in the air. Several larger condensate droplets about 1-2 mm appear on the substrates after 3 h condensation. This continuous jumping motion of the condensate will be beneficial in delaying frosting. The results demonstrate that dense nanostructures on copper surfaces are superior to loose lattice-like microstructures on aluminum surfaces for preventing the formation of large droplets condensate and in delaying the icing. The large water droplets of 2-3 mm in diameter that would form on a common metal foil are sharply decreased to dozens of microns and small droplets are formed on a modified surface, which will then drift down like a fog.

Quan, Yun-Yun; Jiang, Pei-Guo; Zhang, Li-Zhi

2014-09-01

386

QTL analyses and comparative genetic mapping of frost tolerance, winter survival and drought tolerance in meadow fescue (Festuca pratensis Huds.).  

PubMed

Quantitative trait loci (QTLs) for frost and drought tolerance, and winter survival in the field, were mapped in meadow fescue (Festuca pratensis Huds.) and compared with corresponding traits in Triticeae and rice to study co-location with putatively orthologous QTLs and known abiotic stress tolerance genes. The genomes of grass species are highly macrosyntenic; however, the Festuca/Lolium and Triticeae homoeologous chromosomes 4 and 5 show major structural differences that is especially interesting in comparative genomics of frost tolerance. The locations of two frost tolerance/winter survival QTLs on Festuca chromosome 5F correspond most likely to the Fr-A1 and Fr-A2 loci on wheat homoeologous group 5A chromosomes. A QTL for long-term drought tolerance on chromosome 3F (syntenic with rice 1) support evidence from introgression of Festuca genome segments onto homoeologous Lolium chromosomes (3L) that this genome region is an excellent source of tolerance towards drought stress. The coincident location of several stress tolerance QTL in Festuca with QTL and genes in Triticeae species, notably dehydrins, CBF transcription factors and vernalisation response genes indicate the action of structural or regulatory genes conserved across evolutionarily distant species. PMID:21505831

Alm, Vibeke; Busso, Carlos S; Ergon, Ashild; Rudi, Heidi; Larsen, Arild; Humphreys, Michael W; Rognli, Odd Arne

2011-08-01

387

Thaw-Subsidence Measurements in the Circumpolar Active Layer Monitoring (CALM) Program  

NASA Astrophysics Data System (ADS)

Vertical movement of the ground surface due to frost heave and thaw subsidence is a common phenomenon in permafrost regions. The magnitude of this movement varies both temporally and spatially, owing to interannual climatic variability at the ground surface and to local variations of soil moisture. Because measurements at point locations made using frost/thaw tubes at CALM sites during the 1990s indicated that penetration of thaw into the ice-rich transient layer may not be reflected in records of active-layer thickness, spatial sampling experiments were initiated early in this decade at several sites in Alaska and Russia. Differential Global Positioning Systems (DGPS) technology was employed at sites in the northern Brooks Range Foothills and on the Arctic Coastal Plain of northern Alaska. Traditional theodolite survey methods were used at sites in the European Russian Arctic. The resulting heave/subsidence records, in conjunction with temperature and active-layer measurements, were used to evaluate regional and site-specific factors affecting the spatial and temporal variability of frost heave and subsidence. Heave and settlement show patterns of spatial variation similar to those of active-layer thickness (ALT). Results from all locations indicate a monotonic increase in thaw penetration into the upper ice-rich permafrost during the period of observation. The CALM II (2004-09) measurement protocol accommodates long- term subsidence measurements, and instrumentation is being developed for deployment at most CALM observatories.

Nelson, F. E.; Shiklomanov, N. I.; Streletskiy, D. A.; Little, J. D.; Maxhitova, G. G.; Hinkel, K. M.

2007-12-01

388

Growth of C02 frost thickness near Chasma Borealis during northern winter and spring.  

SciTech Connect

Epithermal neutron fluxes measured using the Neutron Spectrometer component of the Mars OdysscNGamma-Ray Spectrometer suite of instruments were studied to determ i ne the spatial and temporal dependence of CO2 frost cover of the nor t h polar cap for L, between 329 and 99 arcoccntric longitude. This time period spans the la t e northern xvinter through summer solstice . In the absence of a CO, cuvcr, the entire basement terrain p o l eward of about +55 latitude is vm, rich in I1 :0 . The consequent enhanced abundance of hydrogen in near-surface soils leads to an anomaluusly low flux of oumardly leaking cpithcrmal ncutrons, wh i ch is a prominent signatu r e of epi t hermal neutron maps measured after about L, = 90 . Because the epithermal neutron flux rises monotonically w i t h increasing thickness of t h e CO . fros t cover, it provides a robust measure of the CO2 thickness in space and time .

Feldman, W. C. (William C.); Boynton, W. V. (William V.); Prettyman, T. H. (Thomas H.); Kelly, N.; Maurice, S. (Sylvestre)

2003-01-01

389

Seasonal polar carbon dioxide frost on Mars: Spatiotemporal quantification of carbon dioxide utilizing 2001 Mars Odyssey gamma ray spectrometer data  

NASA Astrophysics Data System (ADS)

The exchange of carbon dioxide between the atmosphere and the polar caps on Mars creates a seasonal cycle of growth and retreat of the polar caps. As the major component of the Martian atmosphere, CO 2 condenses in the polar regions of the planet during the winter seasons and precipitates as CO 2 frost. It then sublimes during the spring and summer seasons in response to solar radiation. Through natural radioactivity or when exposed to cosmic rays, elements in the Martian near-subsurface (uppermost meter) emit gamma rays with distinct, characteristic energies. The Gamma Ray Spectrometer (GRS) onboard the 2001 Mars Odyssey satellite is used to measure the gamma rays coming from the Martian regolith to calculate elemental distributions, abundances, and temporal variations in the gamma ray flux. Changes in the CO 2 frost over time can be quantified by observing attenuation effects of H (2223 keV hydrogen) and 40K (1461 keV potassium) gamma ray signals transmitted through various depths of polar CO 2 overburden throughout the Martian seasons. Conclusions are drawn about the spatial extent, column density, and mass of Mars' seasonal polar caps as a function of time utilizing GRS data. Columnar thickness and mass results are discussed and plotted for latitudes including 60° and poleward. GRS observations are compared to predictions from the NASA Ames Research Center Mars General Circulation Model (ARC GCM) and to similar experimental results from the Mars Odyssey High Energy Neutron Detector (HEND) and the Neutron Spectrometer (NS). Models for north and south polar atmosphere and regolith distributions are incorporated, and the results indicate that the assumption of a 100%, H 2 O-ice residual cap underlying the seasonal frost in the north is accurate. The GRS CO 2 frost observations are in good agreement with the other studies mentioned, in particular for the timing of the beginning of frost deposition to the complete sublimation of surface CO 2 back into the atmosphere. The total amount of condensed CO 2 mass derived from GRS data is on the order of 6.0 × 10 15 kg and verifies previous reports that ~25% of the total Martian exchangeable-CO 2 reservoir participates in the ground-atmosphere cycle.

Kelly, Eleanor Jane

2006-06-01

390

Comparative ANNs with different input layers and GA-PLS study for simultaneous spectrofluorimetric determination of melatonin and pyridoxine HCl in the presence of melatonin’s main impurity.  

PubMed

Melatonin (MLT) has many health implications, therefore it is important to develop specific analytical methods for the determination of MLT in the presence of its main impurity, N-{2-[1-({3-[2-(acetylamino)ethyl]-5-methoxy-1H-indol-2-yl}methyl)-5-methoxy-1H-indol-3-yl]ethyl}acetamide (DMLT) and pyridoxine HCl (PNH) as a co-formulated drug. This work describes simple, sensitive, and reliable four multivariate calibration methods, namely artificial neural network preceded by genetic algorithm (GA-ANN), principal component analysis (PCA-ANN) and wavelet transform procedures (WT-ANN) as well as partial least squares preceded by genetic algorithm (GA-PLS) for the spectrofluorimetric determination of MLT and PNH in the presence of DMLT. Analytical performance of the proposed methods was statistically validated with respect to linearity, accuracy, precision and specificity. The proposed methods were successfully applied for the assay of MLT in laboratory prepared mixtures containing up to 15% of DMLT and in commercial MLT tablets with recoveries of no less than 99.00%. No interference was observed from common pharmaceutical additives and the results compared favorably with those obtained by a reference method. PMID:23344205

Darwish, Hany W; Attia, Mohamed I; Abdelhameed, Ali S; Alanazi, Amer M; Bakheit, Ahmed H

2013-01-01

391

MoO3/Ag/MoO3 anode in organic photovoltaic cells: Influence of the presence of a CuI buffer layer between the anode and the electron donor  

NASA Astrophysics Data System (ADS)

MoO3/Ag/MoO3 (MAM) multilayer structures (layers thickness 20 nm/10 nm/35 nm) are used as anode in CuPc/C60/Alq3/Al organic photovoltaic cells. The averaged transmittance (400 nm-800 nm) of these MoO3/Ag/MoO3 multilayer structures is 70% ± 2% and their sheet resistance is 3.5 ± 1.0 ?/sq. When these multilayer structures are used as anode, the power conversion efficiency of the MoO3/Ag/MoO3/CuPc/C60/Alq3/Al cells is around 1%, this efficiency is increased of 50% when a thin CuI film (3 nm) is introduced at the interface between the anode and the organic film. This improvement is attributed to the templating effect of CuI on the CuPc molecules.

Makha, M.; Cattin, L.; Lare, Y.; Barkat, L.; Morsli, M.; Addou, M.; Khelil, A.; Bernède, J. C.

2012-12-01

392

Mixed convection boundary layer flow at the lower stagnation point of a sphere embedded in a porous medium in presence of heat source/sink: Constant heat flux case  

NASA Astrophysics Data System (ADS)

The steady mixed convection flow of an incompressible viscous fluid over an isoflux sphere embedded in a porous medium with the existence of heat source/sink is theoretically considered for both the assisting and opposing flow cases with small Prandtl number. The transformed equations of the non-similar boundary layer at the lower stagnation point of the sphere are solved numerically using a finite-difference method known as the Keller-box scheme. Numerical results are presented for the skin friction coefficient and the local wall temperature, as well as the velocity and temperature profiles for different values of the porosity parameter, the heat source/sink parameter and the mixed convection parameter for air. It is noticed that the solution has two branches in a certain range of the mixed convection parameter.

Fauzi, Nur Fatihah; Ahmad, Syakila; Pop, Ioan

2014-07-01

393

Atmospheric circulation associated with extreme generalized frosts persistence in central-southern South America  

NASA Astrophysics Data System (ADS)

Generalized frosts (GF) in central-southern South America have a strong impact due to their spatial extension, and they are especially important when they become persistent. This paper aims at identifying the atmospheric circulation features that determine the extreme GF persistence, i.e. very persistent and without persistence, and the differences between them, during the 1961-1990 winters. Since the GF without persistence group outnumbers the other one, two subgroups are composed with events selected from winters with maximum and minimum frequency of GF occurrence, respectively. Additionally, the individual event of July 1988 within the very persistent GF group is analyzed due to its exceptional persistence. GF persistence is mainly conditioned by two large-scale dynamic factors. One is the Rossby wave train propagation across the Pacific Ocean, and the other one is the location with respect to the continent and the magnitude of the confluence in the jet entrance region in subtropical latitudes. A predominantly meridional Rossby wave train propagation with a confluence region to the west of the continent prior to the event favors GF with intermediate (null) persistence depending on the greater (lesser) jet acceleration. This is conditioned by the magnitude of the confluence, which, in turn, depends on the disposition of the wave train propagation pattern. Instead, an essentially zonal propagation with a confluence region to the east of the continent favors the GF persistence for several days, yet if there is no confluence the event does not persist. The greatest persistence of an event combines the confluence/diffluence of the jet entrance/exit region, which depends on the disposition with respect to the continent of the zonally propagating Rossby wave trains.

Müller, Gabriela V.; Berri, Guillermo J.

2012-03-01

394

Carbon-Dioxide Frost Settling from Seasonal Outbursts on Mars (Movie)  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site] [figure removed for brevity, see original site] Frame #1 FRT00004959, Ls 195 Frame #2 FRT000049C2, Ls 196 [figure removed for brevity, see original site] [figure removed for brevity, see original site] Frame #3 FRT00004B45, Ls 199 Frame #4 FRT000059E2, Ls 226

Mars' seasonal caps consist of frozen carbon dioxide mixed with smaller amounts of water ice frost and dust. The different composition of Mars' seasonal caps than Earth's seasonal caps (water-ice snow), plus the lower pressure of the Martian atmosphere, inevitably make springtime recession of the seasonal cap different than the snowmelt that characterizes retreat of Earth's seasonal cap. To monitor Mars' seasonal changes, CRISM repeatedly targets specific regions as Mars' seasons change. Results shown here are evidence that as warming carbon-dioxide ice vaporizes, some is trapped under the ice slab from which pressurized outbursts occur. The released gas expands, cools, and some of it refreezes and falls back to the surface as bright fans.

The region shown in this movie, known informally as Manhattan, is located at 86.3 degrees south latitude, 99 degrees east longitude. To represent the content of the spectral images, two versions of the data are shown side-by-side. The left image was constructed from extended visible wavelengths, to look similar to color images from the High Resolution Imaging Science Experiment (HiRISE) camera. The right image is infrared false-color, with red being the reflectance at 1.30 micrometers, green being depth of the water ice absorption centered at 1.5 micrometers, and blue being depth of the carbon dioxide ice absorption centered at 1.435 micrometers. In this color scheme, surfaces with higher water ice content will appear greenish, while bright carbon dioxide ice will appear magenta. Areas covered by dust will appear dark. In both images, north is to the right. The four time steps in the movie were taken at solar longitudes (Ls) ranging from 195 through 226. (Solar longitude is a measure of seasons, where 180 is southern spring equinox and 270 is southern summer solstice.)

The first frame (image FRT00004959, Ls 195) shows a number of spots and dark fan-shaped features, with a higher concentration of spots on a slope in the middle of the scene. The dark fans show multiple directions, generally indicating wind coming out of the east. The second frame (image FRT000049C2, Ls 196) was taken just a few days after the prior one and starts to show color variations in the fans.

The third frame (image FRT00004B45, Ls 199) records appearance of bright (bluish) fans in addition to the dark fans. The bright fans are slightly more bluish in the false-color image at right, indicating enrichment in carbon dioxide ice. The tails of the dark fans are more greenish, indicated a slight enhancement of water ice. The fourth and final frame (image FRT000059E2, Ls 226) shows distinct bright fans that appear magenta in the false-color image, indicating carbon dioxide ice with little evidence of water ice. However the surrounding surface is greenish, suggesting small amounts of water ice contamination. The tails of the dark fans appear to be more greenish in the infrared than the surrounding ice, suggesting a slight enhancement of the water ice contamination. The difference between the directions of dark and bright fans suggests changes in the wind direction, perhaps as part of a diurnal cycle or pattern.

CRISM science team members working with these data believe that they are seeing evidence for a process first proposed based on data from the Thermal Imaging System (THEMIS) instrument on Mars Odyssey. In this hypothesis, sunlight penetrating the ice warms the underling soil and causes carbon dioxide frost to vaporize at its base. At first the gas is trapped under the frost; when it is released, the e

2007-01-01

395

Application of the Java Message Service in mobile monitoring environments Martin Kuehnhausen , Victor S. Frost  

E-print Network

Application of the Java Message Service in mobile monitoring environments Martin Kuehnhausen Ã? on trains. The Java Message Service (JMS) presents a flexible transport layer for asynchronous communication

Kansas, University of

396

Agricultural losses related to frost events: use of the 850 hPa level temperature as an explanatory variable of the damage cost  

NASA Astrophysics Data System (ADS)

The objective of this study is to analyze frost damaging events in agriculture, by examining the relationship between the daily minimum temperature at the lower atmosphere (at the pressure level of 850 hPa) and crop production losses. Furthermore, the study suggests a methodological approach for estimating agriculture risk due to frost events, with the aim to estimate the short-term probability and magnitude of frost-related financial losses for different levels of 850 hPa temperature. Compared with near surface temperature forecasts, temperature forecast at the level of 850 hPa is less influenced by varying weather conditions, as well as by local topographical features, thus it constitutes a more consistent indicator of the forthcoming weather conditions. The analysis of the daily monetary compensations for insured crop losses caused by weather events in Greece, during the period 1999-2011, shows that frost is the major meteorological phenomenon with adverse effects on crop productivity in the largest part of the country. Two regions of different geographical latitude are further examined, to account for the differences in the temperature ranges developed within their ecological environment. Using a series of linear and logistic regressions, we found that minimum temperature (at 850 hPa level), grouped in three categories according to its magnitude, and seasonality are significant variables when trying to explain crop damage costs, as well as to predict and quantify the likelihood and magnitude of frost damaging events.

Papagiannaki, K.; Lagouvardos, K.; Kotroni, V.; Papagiannakis, G.

2014-01-01

397

Proteins Involved in Distinct Phases of Cold Hardening Process in Frost Resistant Winter Barley (Hordeum vulgare L.) cv Luxor  

PubMed Central

Winter barley is an economically important cereal crop grown in higher latitudes and altitudes where low temperatures represent an important environmental constraint limiting crop productivity. In this study changes in proteome of leaves and crowns in a frost tolerant winter barley cv. Luxor in relation to short and long term periods of cold followed by a brief frost treatment were studied in order to disclose proteins responsible for the cold hardening process in distinct plant tissues. The mentioned changes have been monitored using two dimensional difference gel electrophoresis (2D-DIGE) with subsequent peptide-mapping protein identification. Regarding approximately 600–700 distinct protein spots detected on 2D gels, there has been found at least a two-fold change after exposure to low temperatures in about 10% of proteins in leaves and 13% of proteins in crowns. Protein and nitrogen metabolic processes have been influenced by low temperature to a similar extent in both tissues while catabolism, carbohydrate metabolism and proteins involved in stress response have been more affected in crowns than in leaves. The range of changes in protein abundance was generally higher in leaves and chloroplast proteins were frequently affected which suggests a priority to protect photosynthetic apparatus. Overall, our data proved existence of slightly different response strategies to low temperature stress in crowns and leaves, i.e., tissues with different biological role. Moreover, there have been found several proteins with large increase in accumulation, e.g., 33 kDa oxygen evolving protein of photosystem II in leaves and “enhanced disease susceptibility 1” in crowns; these proteins might have potential to indicate an enhanced level of frost tolerance in barley. PMID:23584021

Hlavá?ková, Iva; Vítámvás, Pavel; Šantr??ek, Ji?í; Kosová, Klára; Zelenková, Sylva; Prášil, Ilja Tom; Ovesná, Jaroslava; Hynek, Radovan; Kodí?ek, Milan

2013-01-01

398

Dehydration and osmotic adjustment in apple stem tissue during winter as it relates to the frost resistance of buds.  

PubMed

In deciduous trees, measurement of stem water potential can be difficult during the leafless period in winter. By using thermocouple psychrometry, osmotic water potentials (?o; actual ?o: ?o(act); ?o at full saturation: ?o(sat)) of expressed sap of bark and bud tissue were measured in order to test if the severity of winter desiccation in apple stems could be sufficiently assessed with ?o. Water potentials were related to frost resistance and freezing behaviour of buds. The determination of ?o reliably allowed winter desiccation and osmotic adjustments in apple stem tissue to be assessed. In winter in bark tissue, a pronounced decrease in ?o(act) and ?o(sat) was found. Decreased ?o(sat) indicates active osmotic adjustment in the bark as observed earlier in the leaves of evergreen woody plants. In terminal bud meristems, no significant osmotic adjustments occurred and dehydration during winter was much less. Osmotic water potentials, ?o(act) and ?o(sat), of bud tissue were always less negative than in the bark. To prevent water movement and dehydration of the bud tissue via this osmotic gradient, it must be compensated for either by a sufficiently high turgor pressure (?p) in bark tissue or by the isolation of the bud tissue from the bark during midwinter. During freezing of apple buds, freeze dehydration and extra-organ freezing could be demonstrated by significantly reduced ?o(act) values of bud meristems that had been excised in the frozen state. Infrared video thermography was used to monitor freezing patterns in apple twigs. During extracellular freezing of intact and longitudinally dissected stems, infrared differential thermal analysis (IDTA) images showed that the bud meristem remains ice free. Even if cooled to temperatures below the frost-killing temperature, no freezing event could be detected in bud meristems during winter. In contrast, after bud break, terminal buds showed a second freezing at the frost-killing temperature that indicates deep supercooling. Our results demonstrate the applicability of thermocouple psychrometry for the assessment of winter desiccation in stem tissues of deciduous trees and corroborate the finding that dormant apple buds survive by extra-organ freezing and do not deep supercool. In addition, they indicate that significant changes of the frost-survival mechanism can occur during the apple bud development in spring. PMID:23939553

Pramsohler, Manuel; Neuner, Gilbert

2013-08-01

399

An investigation of the use of lime as a soil additive to modify the detrimental effects of frost action  

E-print Network

of specimen) with 82 (tension at face 2) held at aero . Figure 3, a, Ths effect of grain siss on frost heave . . . ~ Relation between grain siae of uniform quarts powder and height of capillary rise in 24. hours Figure $o ktterberg Limit variations... with the addition of lime . Figure 5. General view of the equipment Figure 6. Samples with insulation ready for testing Figure 7 Base plate and water reservoir shaving heat ex- 55 change coil Figure 8. Bquipment used in the preparation of samples . Figure Q...

Earnest, Clyde Talley

2012-06-07

400

Presence in Teaching  

ERIC Educational Resources Information Center

This article articulates a theory of "presence" in teaching and seeks to establish a theoretical foundation for presence that can serve as a platform for further research. It seeks to address the current educational climate that sees teaching as a check list of behaviors, dispositions, measures, and standards, and to articulate the essential but…

Rodgers, Carol R.; Raider-Roth, Miriam B.

2006-01-01

401

Ground Water and Frost Induced Seismic Velocity Changes in Ketzin (Germany)  

NASA Astrophysics Data System (ADS)

The principle of Seismic Interferometry (SI) is that the correlation of a random wave field like seismic noise recorded by distant receivers can be used to infer the Green function (or at least part of it) of the medium between the receivers. Beside tomographic inversion for the subsurface velocity it can also be used to detect small temporal changes in the propagation of the seismic wave field. As these changes can be related to changes of elastic properties in the propagation medium, SI can characterize dynamic processes in the earth's crust. This technique was successfully applied, inter alia, to monitor seasonal variations in response to environmental influences, shaking caused by earthquakes or material changes due to the eruption of volcanoes. We work with data acquired with a seismic network in Ketzin (Brandenburg, Germany), where CO2 is injected into a saline aquifer at a depth of about 650 m. We calculated daily cross-correlation functions (CCFs) of the ambient noise field for a time period of about 4 years from the beginning of the injection. Spectra showed that the frequency band between 1 and 3.5 Hz does neither show an annual periodicity (like for microseism) nor temporal shifts of peak frequencies. For this frequency band we estimated the noise propagation direction over two years and found a predominant direction from north-east. This direction matches with the location of a large wind park a few km away from the array. The direction of the noise wave field shows a good stability, which excludes variations of the noise source distribution as a cause of spurious velocity variations. To analyze possible velocity changes for each day, we computed stretched versions of a reference CCF and calculated correlation values between different time windows in the coda part of the stretched traces and the reference trace. We can observe velocity variations with a period of approx. one year that are not caused by the CO2 injection. Due to the almost continuous injection of CO2 we would expect a monotonic decrease of the seismic velocities if caused by the CO2. Based on an amplitude decrease when using time windows in the later part of the coda, we show that the variations must be generated in the shallow subsurface. A comparison to ground water level data reveals a direct correlation between the depth of the ground water level and the seismic velocity. The influence of ground frost on the seismic velocities is documented in a sharp increase of velocity when the maximum daily temperature does not exceed 0°C.

Gassenmeier, Martina; Sens-Schönfelder, Christoph; Korn, Michael

2014-05-01

402

Aggregate-cement paste transition zone properties affecting the salt-frost damage of high-performance concretes  

SciTech Connect

The influence of the cement paste-aggregate interfacial transition zone (ITZ) on the frost durability of high-performance silica fume concrete (HPSFC) has been studied. Investigation was carried out on eight non-air-entrained concretes having water-to-binder (W/B) ratios of 0.3, 0.35 and 0.42 and different additions of condensed silica fume. Studies on the microstructure and composition of the cement paste have been made by means of environmental scanning electron microscope (ESEM)-BSE, ESEM-EDX and mercury intrusion porosimetry (MIP) analysis. The results showed that the transition zone initiates and accelerates damaging mechanisms by enhancing movement of the pore solution within the concrete during freezing and thawing cycles. Cracks filled with ettringite were primarily formed in the ITZ. The test concretes having good frost-deicing salt durability featured a narrow transition zone and a decreased Ca/Si atomic ratio in the transition zone compared to the bulk cement paste. Moderate additions of silica fume seemed to densify the microstructure of the ITZ.

Cwirzen, Andrzej; Penttala, Vesa

2005-04-01

403

Copyright 2008 by the author(s). Published here under license by the Resilience Alliance. Wunder, S., B. Campbell, P. G. H. Frost, J. A. Sayer, R. Iwan, and L. Wollenberg. 2008. When donors get  

E-print Network

, S., B. Campbell, P. G. H. Frost, J. A. Sayer, R. Iwan, and L. Wollenberg. 2008. When donors get cold) that Never Happened Sven Wunder 1 , Bruce Campbell 2,3 , Peter GH Frost 1 , Jeffrey A. Sayer 4 , Ramses Iwan

Vermont, University of

404

1 CEB,TheFutureofCorporateIT2013-2017: FiveOpportunitiestoDriveProductivityandGrowthintheNewWorkEnvironment 2 Frost&Sullivan: UCCMarketPredictionsfor2013andBeyond,December2012 3 IDG Enterprise Unified Communications and Collaboration Survey, March 2012 4  

E-print Network

OpportunitiestoDriveProductivityandGrowthintheNewWorkEnvironment 2 Frost&Sullivan: UCCMarketPredictionsfor2013andBeyond,December2012 3 IDG Enterprise Unified collaboration: The New Business Reality, March 2012 5 Frost & Sullivan, North American Video Conferencing

Fisher, Kathleen

405

Color and albedo of the south polar layered deposits on Mars  

NASA Astrophysics Data System (ADS)

Five color/albedo units, including polar frost, have been recognized and mapped in the southern layered deposits on Mars. Atmospheric dust scattering was measured in shadows and modeled in order to remove the component of brightness in Mars images due to the atmosphere and quantify the albedo and color of the surface. The layered deposits appear to be mantled by red dust, except where eolian stripping has exposed the underlying bedrock. Dark material has been deposited in topographic depressions in much of the south polar region, including the layered deposits. The available observational data suggest that the layered deposits are composed of bright dust, ice, and a small amount of dark material. If the dark material is sand, a periodic change in polar winds seems required in order to transport the sand poleward into the layered terrain. In any case, the observations are not consistent with the layered deposits being composed only of bright dust and ice.

Herkenhoff, K. E.; Murray, B. C.

1990-02-01

406

Hot Bottom Burning Nucleosynthesis in 6 M fi Stellar Models J. C. Lattanzio and C. A. Frost a , R. C. Cannon b , and P. R. Wood c .  

E-print Network

1 Hot Bottom Burning Nucleosynthesis in 6 M fi Stellar Models J. C. Lattanzio and C. A. Frost a , R, Australia We present a brief summary of some nucleosynthesis calculations for 6 M fi stellar models. Theoretical studies are desperately needed to quantify the nucleosynthesis which occurs in intermediate mass

Lattanzio, John

407

Books on "Plant Respiration"(1932-1960): From Walter Stiles to Felix Frost Blackman to W.O. James to Harry Beevers  

E-print Network

1 Books on "Plant Respiration"(1932-1960): From Walter Stiles to Felix Frost Blackman to W.O. James. Leach (1932) Respiration in Plants. Methuen's Monographs on Biological Subjects. Chemical Publication of their 124 page small (6 7/8 inch x 4 3/8 inch) book "Respiration in Plants": "The supreme importance

Govindjee "Gov"

408

John Steinbeck: "The Pearl," Adapted by Warren Frost and Dramatized for the Kennedy Center by Nick Olcott. Cue Sheet for Students.  

ERIC Educational Resources Information Center

This performance guide is designed for teachers to use with students before and after a performance of "The Pearl" by John Steinbeck, adapted by Warren Frost and dramatized for the Kennedy Center by Nick Olcott. It is in the form of a Director's Notebook--a scrapbook/journal of clippings, memos, lists, illustrations, notes, and other items--to…

Carr, John C.

409

Influence of Mineral Nitrogen Source on Growth and Frost Resistance of White Clover (Trifolium Repens L.) and Timothy (Phleum Pratense L.) Seedlings  

Microsoft Academic Search

The main purpose of this study was to compare the effects of different doses of nitrate, ammonium and ammonium plus nitrate on frost hardiness in seedlings of white clover (Trifolium repens L.) and timothy (Phleum pratense L.). In addition, top growth of the plants was observed. Plants were grown under controlled conditions in a phytotron, fertilized with various levels of

Olavi Junttila; Mette M. Svenning; Kirsti Røsnes

1995-01-01

410

Lidar observations of Arctic polar stratospheric clouds, 1988 - Signature of small, solid particles above the frost point  

NASA Technical Reports Server (NTRS)

The paper presents recent (January 1988) Arctic airborne lidar data which suggest that Type I polar stratospheric clouds (PSCs) are composed of small solid particles with radii on the order of 0.5 micron. PSCs were observed remotely in the 21-24 km altitude range north of Greenland during a round-trip flight from Andenes, Norway on January 29, 1988, aboard the NASA Wallops Flight Facility P-3 Orion aircraft. Synoptic analyses at the 30-mb level show local temperatures of 191-193 K, which are well above the estimated frost point temperature of 185 K; this suggests that the PSCs were probably of the binary HNO3-H2O (Type I) class.

Poole, L. R.; Osborn, M. T.; Hunt, W. H.

1988-01-01

411

Atlas of reflectance spectra of terrestrial, lunar and meteoritic powders and frosts from 92 to 1800 nm  

NASA Technical Reports Server (NTRS)

The reflectance spectra of powdered samples of selected minerals, meteorites, lunar materials and frosts are presented as an aid in the interpretation of present and future remote sensing data of solar system objects. Spectra obtained in separate wavelength regions have been combined and normalized, yielding coverage from 92 to 1800 nm. Spectral features include reflectance maxima in the far UV region produced by valence-conduction interband transitions, and reflectance minima in the near UV, visible and near IR regions, produced by charge transfer and crystal field transitions. Specific maxima and minima are diagnostic of mineral type and composition; additionally, the minerals present in mixtures such as meteorites and lunar samples can be determined.

Wagner, Jeffrey; Hapke, Bruce; Wells, Eddie

1987-01-01

412

A next generation sequencing of Arctic bacteria in snow and frost flowers: identification, abundance and freezing nucleation  

NASA Astrophysics Data System (ADS)

During the spring of 2009, as part of the Ocean-Atmosphere-Sea Ice-Snowpack (OASIS) campaign in Barrow, Alaska, USA, we examined the identity, population, freezing nucleation ability of the microbial communities of five different snow types and frost flowers. In addition to the conventional culture-based PCR identification approach, we deployed a state-of-the-art genomic Next Generation Sequencing (NGS) technique to examine diverse bacterial communities in Arctic samples. 11-18 known phyla or candidate divisions were identified with the great majority of sequences (12.3-83.1%) belonging to one of the five major phyla: Proteobacteria, Actinobacteria, Bacteroidetes, Firmicutes and Cyanobacteria. At the genus level, 101-245 different genera were detected. The highest number of cultivable bacteria in cultured samples was observed in frost flowers (FF) and accumulated snow (AS) with 325 ± 35 and 314 ± 142 CFU mL-1, respectively; and for cultivable fungi 5 ± 1 CFU mL-1 in windpack (WP) and blowing snow (BS). Complementary morphology and ice-nucleating abilities of the identified taxa were obtained using high resolution electron microscopy and ice nucleation cold-plate, respectively. Freezing point temperatures for bacterial isolate ranged from -20.3 ± 1.5 to -15.7 ± 5.6 °C, and for melted samples from 9.5 ± 1.0 to 18.4 ± 0.1 °C. An isolate belonging to the Bacillus species (96% similarity) had ice nucleation activity of -6.8 ± 0.2 °C. Comparison with Montreal urban snow, revealed a seemingly diverse community of bacteria exists in the Arctic with many originating from distinct ecological environments, and we discuss the potential impact of microbial snow in the freezing and melting process of the snowpack in the Arctic.

Mortazavi, R.; Attiya, S.; Ariya, P. A.

2014-12-01

413

Engineering Presence: an Experimental Strategy  

Microsoft Academic Search

Over the centuries artists have developed a range of techniques for inducing a sense of presence in an audience. The goals of these are however essentially open-ended. The presence engineer, on the other hand aims to use presence for practical applications. After summarizing ways in which presence can be detected and measured this paper places 21 st century presence techniques

Fabrizio DAVIDE; Richard WALKER

414

Snippets from the past: the evolution of Wade Hampton Frost's epidemiology as viewed from the American Journal of Hygiene/Epidemiology.  

PubMed

Wade Hampton Frost, who was a Professor of Epidemiology at Johns Hopkins University from 1919 to 1938, spurred the development of epidemiologic methods. His 6 publications in the American Journal of Hygiene, which later became the American Journal of Epidemiology, comprise a 1928 Cutter lecture on a theory of epidemics, a survey-based study of tonsillectomy and immunity to Corynebacterium diphtheriae (1931), 2 papers from a longitudinal study of the incidence of minor respiratory diseases (1933 and 1935), an attack rate ratio analysis of the decline of diphtheria in Baltimore (1936), and a 1936 lecture on the age, time, and cohort analysis of tuberculosis mortality. These 6 American Journal of Hygiene /American Journal of Epidemiology papers attest that Frost's personal evolution mirrored that of the emerging "early" epidemiology: The scope of epidemiology extended beyond the study of epidemics of acute infectious diseases, and rigorous comparative study designs and their associated quantitative methods came to light. PMID:24022889

Morabia, Alfredo

2013-10-01

415

Snippets From the Past: The Evolution of Wade Hampton Frost's Epidemiology as Viewed From the American Journal of Hygiene/Epidemiology  

PubMed Central

Wade Hampton Frost, who was a Professor of Epidemiology at Johns Hopkins University from 1919 to 1938, spurred the development of epidemiologic methods. His 6 publications in the American Journal of Hygiene, which later became the American Journal of Epidemiology, comprise a 1928 Cutter lecture on a theory of epidemics, a survey-based study of tonsillectomy and immunity to Corynebacterium diphtheriae (1931), 2 papers from a longitudinal study of the incidence of minor respiratory diseases (1933 and 1935), an attack rate ratio analysis of the decline of diphtheria in Baltimore (1936), and a 1936 lecture on the age, time, and cohort analysis of tuberculosis mortality. These 6 American Journal of Hygiene /American Journal of Epidemiology papers attest that Frost's personal evolution mirrored that of the emerging “early” epidemiology: The scope of epidemiology extended beyond the study of epidemics of acute infectious diseases, and rigorous comparative study designs and their associated quantitative methods came to light. PMID:24022889

Morabia, Alfredo

2013-01-01

416

[The differences of the effects of Vrd1 and Ppd-D1 gene alleles on winterhardiness, frost resistance, and yield in winter wheat].  

PubMed

The influence of allelic differences of Vrd1 and Ppd-D1 genes on winterhardiness, frost resistance, yield and its components was studied in recombinant-inbred F5 lines of Odesskaya 16/Bezostaya 1. From 9 to 15% differences in the resistance of recombinant-inbred lines were determined by alternative alleles of Vrd1 gene and 10-16% of Ppd-D1 gene. Interaction of vrd1 and Ppd-D1a alleles led to the higher winterhardiness and frost resistance of tillered plants during the winter. At the same time the significant increase of the period to heading, plant height and the tendency of yield reduction were revealed for vrd1 vrd1 Ppd-D1a Ppd-D1a lines when compared to the lines of Vrd1 Vrd1 Ppd-D1a Ppd-D1a genotype. PMID:19253752

Mokanu, N V; Fa?t, V I

2008-01-01

417

Improved frost tolerance and winter hardiness in proline overaccumulating winter wheat mutants obtained by in vitro-selection is associated with increased carbohydrate, soluble protein and abscisic acid (ABA) levels  

Microsoft Academic Search

In previous studies in vitro-selection of proline overaccumulating lines of winter wheat (Triticum sativum L. cv. Jo 3063) with increased frost tolerance was reported. These traits were found to be genetically stable. In the present\\u000a study the improvement of frost tolerance (winter hardiness) under field conditions is confirmed for F7 progenies of the mutants. Moreover, the mutants accumulated higher levels

Karl Dörffling; Helga Dörffling; Edgar Luck

2009-01-01

418

A GIS Analysis of the Relationship between Sinkholes, Dry-Well Complaints and Groundwater Pumping for Frost-Freeze Protection of Winter Strawberry Production in Florida  

PubMed Central

Florida is riddled with sinkholes due to its karst topography. Sometimes these sinkholes can cause extensive damage to infrastructure and homes. It has been suggested that agricultural practices, such as sprinkler irrigation methods used to protect crops, can increase the development of sinkholes, particularly when temperatures drop below freezing, causing groundwater levels to drop quickly during groundwater pumping. In the strawberry growing region, Dover/Plant City, Florida, the effects have caused water shortages resulting in dry- wells and ground subsidence through the development of sinkholes that can be costly to maintain and repair. In this study, we look at how frost-freeze events have affected West Central Florida over the past 25 years with detailed comparisons made between two cold-years (with severe frost-freeze events) and a warm year (no frost-freeze events). We analyzed the spatial and temporal correlation between strawberry farming freeze protection practices and the development of sinkholes/dry well complaints, and assessed the economic impact of such events from a water management perspective by evaluating the cost of repairing and drilling new wells and how these compared with using alternative crop-protection methods. We found that the spatial distribution of sinkholes was non-random during both frost-freeze events. A strong correlation between sinkhole occurrence and water extraction and minimum temperatures was found. Furthermore as temperatures fall below 41°F and water levels decrease by more than 20 ft, the number of sinkholes increase greatly (N >10). At this time alternative protection methods such as freeze-cloth are cost prohibitive in comparison to repairing dry wells. In conclusion, the findings from this study are applicable in other agricultural areas and can be used to develop comprehensive water management plans in areas where the abstraction of large quantities of water occur. PMID:23326518

Aurit, Mark D.; Peterson, Robert O.; Blanford, Justine I.

2013-01-01

419

A GIS analysis of the relationship between sinkholes, dry-well complaints and groundwater pumping for frost-freeze protection of winter strawberry production in Florida.  

PubMed

Florida is riddled with sinkholes due to its karst topography. Sometimes these sinkholes can cause extensive damage to infrastructure and homes. It has been suggested that agricultural practices, such as sprinkler irrigation methods used to protect crops, can increase the development of sinkholes, particularly when temperatures drop below freezing, causing groundwater levels to drop quickly during groundwater pumping. In the strawberry growing region, Dover/Plant City, Florida, the effects have caused water shortages resulting in dry-wells and ground subsidence through the development of sinkholes that can be costly to maintain and repair. In this study, we look at how frost-freeze events have affected West Central Florida over the past 25 years with detailed comparisons made between two cold-years (with severe frost-freeze events) and a warm year (no frost-freeze events). We analyzed the spatial and temporal correlation between strawberry farming freeze protection practices and the development of sinkholes/dry well complaints, and assessed the economic impact of such events from a water management perspective by evaluating the cost of repairing and drilling new wells and how these compared with using alternative crop-protection methods. We found that the spatial distribution of sinkholes was non-random during both frost-freeze events. A strong correlation between sinkhole occurrence and water extraction and minimum temperatures was found. Furthermore as temperatures fall below 41°F and water levels decrease by more than 20 ft, the number of sinkholes increase greatly (N >10). At this time alternative protection methods such as freeze-cloth are cost prohibitive in comparison to repairing dry wells. In conclusion, the findings from this study are applicable in other agricultural areas and can be used to develop comprehensive water management plans in areas where the abstraction of large quantities of water occur. PMID:23326518

Aurit, Mark D; Peterson, Robert O; Blanford, Justine I

2013-01-01

420

Breeding for the future: what are the potential impacts of future frost and heat events on sowing and flowering time requirements for Australian bread wheat (Triticum aestivium) varieties?  

PubMed

Extreme climate, especially temperature, can severely reduce wheat yield. As global warming has already begun to increase mean temperature and the occurrence of extreme temperatures, it has become urgent to accelerate the 5-20 year process of breeding for new wheat varieties, to adapt to future climate. We analyzed the patterns of frost and heat events across the Australian wheatbelt based on 50 years of historical records (1960-2009) for 2864 weather stations. Flowering dates of three contrasting-maturity wheat varieties were simulated for a wide range of sowing dates in 22 locations for 'current' climate (1960-2009) and eight future scenarios (high and low CO2 emission, dry and wet precipitation scenarios, in 2030 and 2050). The results highlighted the substantial spatial variability of frost and heat events across the Australian wheatbelt in current and future climates. As both 'last frost' and 'first heat' events would occur earlier in the season, the 'target' sowing and flowering windows (defined as risk less than 10% for frost (<0 °C) and less than 30% for heat (>35 °C) around flowering) would be shifted earlier by up to 2 and 1 month(s), respectively, in 2050. A short-season variety would require a shift in target sowing window 2-fold greater than long- and medium-season varieties by 2050 (8 vs. 4 days on average across locations and scenarios, respectively), but would suffer a lesser decrease in the length of the vegetative period (4 vs. 7 days). Overall, warmer winters would shorten the wheat season by up to 6 weeks, especially during preflowering. This faster crop cycle is associated with a reduced time for resource acquisition, and potential yield loss. As far as favourable rain and modern equipment would allow, early sowing and longer season varieties (i.e. in current climate) would be the best strategies to adapt to future climates. PMID:24501066

Zheng, Bangyou; Chenu, Karine; Fernanda Dreccer, M; Chapman, Scott C

2012-09-01

421

Application of Satellite SAR Imagery in Mapping the Active Layer of Arctic Permafrost  

NASA Technical Reports Server (NTRS)

A method of mapping the active layer of Arctic permafrost using a combination of conventional synthetic aperture radar (SAR) backscatter and more sophisticated interferometric SAR (INSAR) techniques is proposed. The proposed research is based on the sensitivity of radar backscatter to the freeze and thaw status of the surface soil, and the sensitivity of INSAR techniques to centimeter- to sub-centimeter-level surface differential deformation. The former capability of SAR is investigated for deriving the timing and duration of the thaw period for surface soil of the active layer over permafrost. The latter is investigated for the feasibility of quantitative measurement of frost heaving and thaw settlement of the active layer during the freezing and thawing processes. The resulting knowledge contributes to remote sensing mapping of the active layer dynamics and Arctic land surface hydrology.

Li, Shu-Sun; Romanovsky, V.; Lovick, Joe; Wang, Z.; Peterson, Rorik

2003-01-01

422

Far-UV, visible, and near-IR reflectance spectra of frosts of H2O, CO2, NH3 and SO2  

NASA Technical Reports Server (NTRS)

Measurements in the 0.1-2.5 micron range are presented for the reflectance spectra of the frosts of several volatiles pertinent to the study of comet nuclei. The frost spectra have distinctive features permitting their identification by spectroscopic reflectance remote sensing, notably in the far UV. It is found that: (1) H2O has a minimum at 0.16 microns and a maximum at 0.13 microns; (2) CO2 has minima near 0.21, 0.18 and 0.125 microns, with maxima at 0.19, 0.135 and 0.120 microns; (3) NH3 is bright at wavelengths longer than 0.21 microns, where reflectance drops to a value of only a few per cent at shorter wavelengths; (4) SO2 has a sharp drop at 0.32 microns, with a minimum at 0.18 microns and a maximum at 0.13 microns. The features in the frost spectra largely correspond to absorption line bands in the gas phase.

Hapke, B.; Wells, E.; Wagner, J.; Partlow, W.

1981-01-01

423

Impacts of a water stress followed by an early frost event on beech (Fagus sylvatica L.) susceptibility to Scolytine ambrosia beetles - Research strategy and first results  

NASA Astrophysics Data System (ADS)

Climate change tends to induce more frequent abiotic and biotic extreme events, having large impacts on tree vitality. Weakened trees are then more susceptible to secondary insect outbreaks, as it happened in Belgium in the early 2000s: after an early frost event, secondary Scolytine ambrosia beetles attacks were observed on beech trees. In this study, we test if a combination of stress, i.e. a soil water deficit preceding an early frost, could render trees more attractive to beetles. An experimental study was set in autumn 2008. Two parcels of a beech forest were covered with plastic tents to induce a water stress by rain interception. The parcels were surrounded by 2-meters depth trenches to avoid water supply by streaming. Soil water content and different indicators of tree water use (sap flow, predawn leaf water potential, tree radial growth) were followed. In autumn 2010, artificial frost injuries will be inflicted to trees using dry ice. Trees attractivity for Scolytine insects, and the success of insect colonization will then be studied. The poster will focus on experiment setting and first results (impacts of soil water deficit on trees).

La Spina, Sylvie; de Cannière, Charles; Molenberg, Jean-Marc; Vincke, Caroline; Deman, Déborah; Grégoire, Jean-Claude

2010-05-01

424

Larval feeding behavior and ant association in frosted elfin, Callophrys irus (Lycaenidae)  

USGS Publications Warehouse

Callophrys irus is a rare and declining lycaenid found in the eastern U.S., inhabiting xeric and open habitats maintained by disturbance. Populations are localized and monophagous. We document a previously undescribed larval feeding behavior in both field and lab reared larvae in which late instar larvae girdled the main stem of the host plant. Girdled stems provide a unique feeding sign that was useful in detecting the presence of larvae in the field. We also observed frequent association of field larvae with several species of ants and provide a list of ant species. We suggest two hypotheses on the potential benefits of stem-girdling to C. irus larvae: 1) Stem girdling provides phloem sap as a larval food source and increases the leaf nutrient concentration, increasing larval growth rates and providing high quality honeydew for attending ants; 2) Stem girdling reduces stem toxicity by inhibiting transport of toxins from roots to the stem.

Albanese, G.; Nelson, M.W.; Vickery, P.D.; Sievert, P.R.

2007-01-01

425

Digital Image Sensor-Based Assessment of the Status of Oat (Avena sativa L.) Crops after Frost Damage  

PubMed Central

The aim of this paper is to classify the land covered with oat crops, and the quantification of frost damage on oats, while plants are still in the flowering stage. The images are taken by a digital colour camera CCD-based sensor. Unsupervised classification methods are applied because the plants present different spectral signatures, depending on two main factors: illumination and the affected state. The colour space used in this application is CIELab, based on the decomposition of the colour in three channels, because it is the closest to human colour perception. The histogram of each channel is successively split into regions by thresholding. The best threshold to be applied is automatically obtained as a combination of three thresholding strategies: (a) Otsu’s method, (b) Isodata algorithm, and (c) Fuzzy thresholding. The fusion of these automatic thresholding techniques and the design of the classification strategy are some of the main findings of the paper, which allows an estimation of the damages and a prediction of the oat production. PMID:22163940

Macedo-Cruz, Antonia; Pajares, Gonzalo; Santos, Matilde; Villegas-Romero, Isidro

2011-01-01

426

Looking at the world through a frosted window: experiences of loneliness among persons with mental ill-health.  

PubMed

Mental ill-health is reported to be of major concern in public health. Persons suffering from mental ill-health are a vulnerable group, and loneliness influences the perception of physical, social, and emotional well-being. However, there are few studies exploring lived experiences of loneliness among people with mental ill-health. This qualitative study aimed to illuminate experiences of loneliness among people with mental ill-health. Five individual, informal conversational interviews were performed and subjected to qualitative content analysis. The main findings showed that experiences of loneliness could be metaphorically described as looking at the world through a frosted window. The experiences of loneliness were multifaceted and altering as well as emotionally and socially excluding. The findings are discussed in relation to Tillich dimensions of loneliness: loneliness as a painful dimension of being alone, and solitude as the enriching dimension of being alone. People suffering from mental ill-health carry a twofolded stigma. They feel socially undesirable because of their mental ill-health, and the social perceptions of lonely people are generally unfavourable. We believe that mental health nurses can support the developing and creative dimension of loneliness through a confirming approach, where people with mental ill-health feel seen, heard, and respected as human beings. PMID:23530616

Lindgren, B-M; Sundbaum, J; Eriksson, M; Graneheim, U H

2014-03-01

427

Digital image sensor-based assessment of the status of oat (Avena sativa L.) crops after frost damage.  

PubMed

The aim of this paper is to classify the land covered with oat crops, and the quantification of frost damage on oats, while plants are still in the flowering stage. The images are taken by a digital colour camera CCD-based sensor. Unsupervised classification methods are applied because the plants present different spectral signatures, depending on two main factors: illumination and the affected state. The colour space used in this application is CIELab, based on the decomposition of the colour in three channels, because it is the closest to human colour perception. The histogram of each channel is successively split into regions by thresholding. The best threshold to be applied is automatically obtained as a combination of three thresholding strategies: (a) Otsu's method, (b) Isodata algorithm, and (c) Fuzzy thresholding. The fusion of these automatic thresholding techniques and the design of the classification strategy are some of the main findings of the paper, which allows an estimation of the damages and a prediction of the oat production. PMID:22163940

Macedo-Cruz, Antonia; Pajares, Gonzalo; Santos, Matilde; Villegas-Romero, Isidro

2011-01-01

428

Ice Lens Formation and Frost Heave at the Phoenix Landing Site  

NASA Technical Reports Server (NTRS)

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

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

2011-01-01

429

Regional Climate Change Influences Frequency of Frost Damage via Changes in Phenology: Effects of the North Pacific Oscillation (Pacific Decadal Oscillation) on Rocky Mountain Wildflowers  

NASA Astrophysics Data System (ADS)

There is a significant correlation (P = .049) between the state of the North Pacific Oscillation (Pacific Decadal Oscillation) and the amount of winter snowfall at the Rocky Mountain Biological Laboratory (2,800m in the Colorado Rocky Mountains). The 1998 change of this inter-decadal mode of variability of the north Pacific atmosphere system to a dry phase has resulted in decreased snowpack, reversing a trend for increasing snowfall since the previous phase change in 1976. The seasonal timing (phenology) of plant growth and flowering at high altitudes is determined almost entirely by the timing of spring snowmelt, even for species that flower at the end of the season, and the decreased snowpack since 1998 combined with warming air temperatures has resulted in significantly earlier initiation of the growing season and subsequent flowering. Flowering in 2002, for example, was the earliest recorded during my 31-year study, and probably the earliest since at least 1935. Frost (with temperatures as low as -6 or -7ºC) is still likely to occur as late as mid-June, however, and a consequence of the earlier beginning of the growing season is that many species have developed sensitive flower buds or other tissues by mid-June that are likely to be killed by frost. From 1994-1998 the average percentage of flower buds of Helianthella quinquenervis (Asteraceae; aspen sunflower) killed by frost was 26 percent(range 0-81), but since the 1998 NPO phase change a mean of 75 percent of flower buds have been killed (range 0-100; over 90 percent for each of the past four years). The loss of flowers from these frosts has consequences for plant demography (fewer seeds results in fewer seedlings), pollinators (which have fewer floral resources), seed predators (e.g., tephritid flies), and parasitoids (e.g., wasps, which have fewer seed predators to parasitize). A suite of wildflower species whose flowering abundance is positively correlated with the amount of winter snowfall has also produced fewer flowers since 1998, potentially exacerbating the effects of frost. Thus this regional climate event appears to be having ecosystem-wide consequences in the Colorado Rocky Mountains. Given the 50-75 year cycle length of the NPO, this area may be at the beginning of a decades-long change in snowfall that will reinforce the effects of global climate warming and result in significant ecosystem responses.

Inouye, D. W.

2004-12-01

430

Effect of soil frost on growing season nitrogen uptake by fine roots of mature trees in northern hardwood forests of the United States  

NASA Astrophysics Data System (ADS)

Forests of the northeastern United States are predicted to experience a decrease in the depth and duration of the winter snowpack over the next 100 years. Even when coupled with warmer winter air temperatures, the absence of snow as insulation can increase soil frost during the winter months. Past research has determined that there are species-level effects of soil frost on dominant forest trees. For example, in stands dominated by sugar maple (Acer saccharum), induced soil frost led to increased fine root mortality and soil nitrate leaching. Soil frost also increased fine root mortality in stands dominated by yellow birch (Betula allegheniensis), but there was no significant change in leaching of soil nitrate. We hypothesized that greater nitrogen (N) losses from stands dominated by sugar maple may be due to reduced N uptake by fine roots of this tree species. To determine the impact of increased soil freezing on fine root uptake of N, we established a snow manipulation experiment in mixed sugar maple/American beech (Fagus grandifolia) forests at the Hubbard Brook Experimental Forest in New Hampshire (n=4 paired snow-removal and reference plots; each 13m X 13m). Snow removal occurred during the first six weeks of winter over two years. During each growing season following snow removal, we used the N depletion technique to measure in situ rates of uptake of ammonium and nitrate by fine roots of sugar maple during the early, peak and late growing season. Among all sampling dates and plots, we observed significantly lower uptake of N as nitrate compared to ammonium. During the first growing season, at moderate ammonium availability (35 ?M N) we observed significantly less uptake of ammonium by fine roots of sugar maple in the snow removal plots relative to the reference plots during the early growing season (April-May), with no significant differences in uptake of ammonium during the peak (July) and late (September) growing season. We observed no differences in uptake of ammonium among the snow removal and references plots at higher ammonium availability (200 ?M N), nor nitrate at either concentration throughout the growing season. Results of our study suggest that the observed increase in N losses following periods of soil frost could be due to a decrease in N uptake by fine roots of mature trees, especially in the early growing season. Our study shows the effects of vegetation responses to climate change on ecosystem nitrogen cycling.

Socci, A. M.; Templer, P. H.

2010-12-01

431

Why Presence Occurs: Evolutionary Psychology, Media Equation, and Presence  

Microsoft Academic Search

Despite the intense interest in the phenomena of presence, there have been limited attempts to explain the fundamental reason why human beings can feel presence when they use media and\\/or simulation technologies. This is mainly because previous studies on presence have focused on \\

Kwan Min Lee

2004-01-01

432

Lava Layering  

NSDL National Science Digital Library

This is a lesson about geologic history. Learners will work together to create models of volcanic lava flows and analyze the layers that form on a planet's surface. They will sequence lava flows produced by multiple eruptions. Students will be asked to observe where the flows travel, make a model, and interpret the stratigraphy. Students will use their volcanic layering model to demonstrate the relative dating and geologic mapping principles to later be applied to satellite imagery. The lesson models scientific inquiry using the 5E instructional model and includes teacher notes and vocabulary.

433

Transport Layer Cornell University  

E-print Network

Transport Layer Ao Tang Cornell University Ithaca, NY 14853 Lachlan L. H. Andrew California is called a "layer". One of the layering structures often used is the five-layer model consisting of the physical layer, the link layer, the network layer, the transport layer and the application layer1 . See

Andrew, Lachlan

434

Genesis and geometry of the Meiklejohn Peak lime mud-mound, Bare Mountain Quadrangle, Nevada, USA: Ordovician limestone with submarine frost heave structures—a possible response to gas clathrate hydrate evolution  

NASA Astrophysics Data System (ADS)

During the Early Middle Ordovician (Early Whiterockian) the Meiklejohn Peak lime mud-mound, a large whaleback or dolphin back dome, grew on a carbonate ramp tens to hundreds of kilometres offshore. This ramp extended from the northwest margin of Laurentia into the open waters of the ancestral Pacific Ocean to the north. The mound developed in an outer ramp environment, in relatively deep and cold water. A steep northern margin with a slope that exceeds 55° characterizes the mound. This margin is split by a 14-m long vertical fracture that separates a zone of slumped, drag-folded and brecciated rocks from the main mass of the mound. Failure along this fracture occurred subcutaneously, as highlighted by covering beds that are folded next to the mound. Brecciated blocks and clasts contain zebra and stromatactis structures indicating that these rocks and structures were lithified early in the history of the mound. The southern end of the mound is less steep and is characterized by large, echinodermal grainstone cross-beds. These deposits are part of a large, subaqueous dune that grew northwards and preceded the main development of the mound. Southward dipping and downlapping layers of mud-mound mudstone and wackestone overlie the dune. These muddy limestone layers are cut in several places by injection dykes and are pierced, near the contact with the underlying dune, by a 25-m long pipe filled with rotated nodular and brecciated mud-mound clasts. This long pipe extends to the edge of the mound and appears to have been a conduit where fluidized materials that came from the mound's interior were vented. The interior of the mound is typified by light grey limestone with zebra bands and stromatactis structures. Both structures represent former cavity systems that are filled with fibrous and bladed calcite and pelleted and laminated geopetal mudstone. Spar bands of zebra limestone often extend for several metres and appear to have been unsupported over these distances. Zebra banded rocks are also accompanied by snout and socket structures and, in some instances, are folded and sheared by curving kink bands. Zebra and stromatactis limestone structures found throughout the mud-mound resemble frost heave and cryoturbation structures identified in both Holocene and Pleistocene cryosols, and in laboratory experiments with advancing freezing fronts in clay-size sediment. Significantly, modern occurrences of methane clathrate hydrate (methane-charged ice) display parallel and digitate layering similar in depositional appearance to that of zebra and stromatactis limestone from Meiklejohn Peak. Early carbonate cements are also commonly associated with these modern clathrate hydrate deposits. Consequently, gas clathrate hydrates may have been the propping agent for zebra and stromatactis structures observed in the mud-mound. In this scenario, carbonate cements would have precipitated and stabilized these structures, both with the consolidation and dissociation of gas clathrate hydrates, and with the oxidation and reduction of associated gases. Stable ?13C and ?18O isotope ratios collected from mudstone and spar of zebra and stromatactis structures indicate that they were lithified in equilibrium with Ordovician seawater. The ?13C isotope ratios recorded at Meiklejohn Peak are similar to ?13C isotopic ratios obtained from ?CO 2 evolving from modern seafloor. These isotopic ratios may indicate that frost heave structures in the Meiklejohn Peak mud-mound are the result of consolidation and dissociation of carbon dioxide clathrate hydrates. Even though the bulk of gas clathrate hydrates identified to date in modern ocean floors are composed of methane, carbon dioxide clathrate hydrates are known from the modern seafloor of the Okinawa Trough. They may also be common in areas of abundant carbonate sediment accumulation, as suggested by recent observations from the Great Australian Bight.

Krause, Federico F.

2001-12-01

435

On Multiple-Layered Vortices  

NASA Technical Reports Server (NTRS)

As part of an ongoing effort to find ways to make vortex flow fields decompose more quickly, photographs and observations are presented of vortex flow fields that indicate the presence of multiple layers of fluid rotating about a common axis. A survey of the literature indicates that multiple-layered vortices form in waterspouts, tornadoes and lift-generated vortices of aircraft. An explanation for the appearance of multiple-layered structures in vortices is suggested. The observations and data presented are intended to improve the understanding of the formation and persistence of vortex flow fields.

Rossow, Vernon J.

2011-01-01

436

Layered Liquids  

NSDL National Science Digital Library

This activity involves an exploration of density. Why does oil float on water? How does drain cleaner sink down into the clogged pipe right through standing water? These questions will be answered as students make a layered "parfait" of colored liquids ba

Eichinger, John

2009-05-30

437

Leaky Layers  

NSDL National Science Digital Library

Figure from the Nature Geoscience article, Geodynamics: Layer cake or plum pudding? by Paul Tackley (Nature Geoscience 1, 157 - 158 (2008)). The figure shows the current understanding of the interaction between the 660 km discontinuity, the core-mantle boundary, downgoing slabs, upwelling plumes.

Tackley, Paul J.; Geoscience, Nature

438

Vitrification in the presence of salts  

SciTech Connect

Glass is an advantageous material for the immobilization of nuclear wastes because of the simplicity of processing and its unique ability to accept a wide variety of waste elements into its network structure. Unfortunately, some anionic species which are present in the nuclear waste streams have only limited solubility in oxide glasses. This can result in either vitrification concerns or it can affect the integrity, of the final vitrified waste form. The presence of immiscible salts can also corrode metals and refractories in the vitrification unit as well as degrade components in the off-gas system. The presence of a molten salt layer on the melt may alter the batch melting rate and increase operational safety concerns. These safety concerns relate to the interaction of the molten salt and the melter cooling fluids. Some preliminary data from ongoing experimental efforts examining the solubility of molten salts in glasses and the interaction of salts with melter component materials is included.

Marra, J.C.; Andrews, M.K.; Schumacher, R.F.

1994-07-01

439

The frequency of growing season frost in the subalpine environment (Medicine Bow Mountains, southeastern Wyoming), the interaction of leaf morphology and infrared radiational cooling and the effects of freezing on native vegetation  

SciTech Connect

The subalpine environment is characterized by the possibility of frost throughout the summer. The frequency and severity of summertime frost episodes appeared particularly dependent on net losses of infrared energy to a cold night sky (radiation frost), as well as air temperature and wind speed. Longwave radiation minima from the night sky were strongly correlated with the occurrence of leaf temperature minima. Leaf temperatures were modeled using an energy balance simulation that quantified the specific effects of ambient air temperature, wind speed, sky infrared radiation, and sky exposure characteristic of this high-elevation environment. Plants growing in exposed and sheltered habitats have characteristic leaf structures (smaller, thicker leaves in more exposed locations) that have been traditionally associated with the total amount of incident sunlight. However, smaller leaves also appear adaptive for reducing the susceptibility to radiation frosts. Larger, more exposed leaves resulted in colder nocturnal leaf temperatures and greater frost frequencies. Microsite sky radiation, microtopography, plant habit and leaf structure all have important implications for estimating growing season length and plant distribution patterns, especially at higher elevations where summer frosts are common. Radiational frosts at night are typically followed by clear skies and full-sun exposure the next morning. The combination of low temperature stress followed by high light exposure can result in strong photoinhibition of photosynthesis. The morphology of a variety of conifer needles as well as of a broadleaf was modeled to evaluate the effect on incident sunlight intensity. Conifer leaf morphology was found to be particularly adaptive for avoiding high incident light conditions compared to broadleaves.

Jordan, D.N.

1995-05-01

440

Lava Layering  

NSDL National Science Digital Library

The Planetary Geology Group at Arizona State University developed this online activity to teach elementary and middle school students "the stratigraphy (layers) of lava flows produced by multiple eruptions" on the moon. The first part of the website provides teachers with background information about the layers of basaltic lava flows that cover about sixteen percent of the Moon as well as how to prepare for the activity and what to expect. Visitors can use the second part of the website as an instruction sheet for the students. The website describes how users can examine the patterns of lava flows on the moon with the help of four simple ingredients: baking soda, vinegar, food coloring, and paper cups. The questions provided at the end will help students understand the process that is taking place in their experiments.

441

Temperature controls on sediment production in the Oregon Coast Range - abiotic frost-cracking processes vs. biotic-dominated processes over the last 40 ka  

NASA Astrophysics Data System (ADS)

The Oregon Coast Range (OCR) is a mid-latitude soil-mantled landscape wherein measured uplift rates are broadly consistent with long-term measured erosion rates. The OCR was unglaciated during the last glacial period (~ 26 to 13 ka) and therefore is considered an ideal steady-state landscape to study and model geomorphic processes. However, previously published paleoclimate data inferred from a 42 ka paleolake fossil archive in the OCR Little Lake watershed (3 km2) strongly suggest that temperatures in the OCR during the last glacial were well within the frost cracking temperature window of -3 to -8 °C. Therefore, we suggest that while present-day OCR sediment production is dominated by biota, specifically trees, frost-driven abiotic processes may have played a significant role in modulating erosion rates and landscape evolution during the last glacial interval. A new sediment core from the Little Lake basin at the lake's edge, centered proximal to hillslopes, spans ~ 50 ka to 20 ka. We observe a fourfold increase in sediment accumulation rates from the non-glacial interval (~50 ka to ~ 26 ka) to the last glacial interval (~ 26 ka to ~ 20 ka), including > 12 m of sediment from the last glacial maximum, dated at 23,062 - 23,581 cal yr B.P. The decreased inferred temperatures and increased sedimentation rates suggest increased sediment production and transport via frost processes during the last glacial interval, in contrast to sediment production and erosion rates controlled by biotic processes in the non-glacial intervals. We present a climate-time series scenario of likely frost-cracking intensity across the entire Oregon Coast Range from the non-glacial interval (at least 3 °C cooler than present-day temperatures) through the glacial interval (7 to 14 °C cooler) and into the Holocene (January temperatures ~ 5 °C). We use the PRISM dataset, which consists of monthly temperature and precipitation for the contiguous United States, to calculate local monthly topographic lapse rates for maximum and minimum temperature and precipitation for the Oregon Coast Range. The topographic lapse rate downscaling method used generates climatically reasonable patterns in mountainous terrain. Using macrofossil data collected from cores in the well-studied Little Lake watershed, we generate climate envelopes using modern climate-species relationships. These inferred paleoclimatic values are then adjusted to the elevations of the hillslopes using the local topographic lapse rates. To calculate frost cracking intensity and depth, (critical controls on sediment production) we use a numerical model, which depends on the mean annual air temperature, soil depth, and daily annual temperature variation over an annual cycle. Applying the model on a 10 m DEM using the inferred paleoclimate data allows us to calculate frost-cracking intensity across the OCR under different climatic conditions at millennial timescales. Climate-induced changes in soil production and transport mechanisms in the soil-mantled OCR likely control changes in erosion rates at millennial time scales, and contradict the widely held assumption that the OCR is an ideal steady state landscape.

Marshall, J. A.; Roering, J. J.; Praskievicz, S. J.; Hales, T. C.; Gavin, D. G.; Bartlein, P. J.

2012-12-01

442

Achieving Presence through Evoked Reality  

PubMed Central

The sense of “Presence” (evolving from “telepresence”) has always been associated with virtual reality research and is still an exceptionally mystifying constituent. Now the study of presence clearly spans over various disciplines associated with cognition. This paper attempts to put forth a concept that argues that it’s an experience of an “Evoked Reality (ER)” (illusion of reality) that triggers an “Evoked Presence (EP)” (sense of presence) in our minds. A Three Pole Reality Model is proposed to explain this phenomenon. The poles range from Dream Reality to Simulated Reality with Primary (Physical) Reality at the center. To demonstrate the relationship between ER and EP, a Reality-Presence Map is developed. We believe that this concept of ER and the proposed model may have significant applications in the study of presence, and in exploring the possibilities of not just virtual reality but also what we call “reality.” PMID:23550234

Pillai, Jayesh S.; Schmidt, Colin; Richir, Simon

2013-01-01

443

Terby's Layers  

NASA Technical Reports Server (NTRS)

2 November 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows light-toned, layered, sedimentary rock exposures in Terby Crater, just north of Hellas Planitia. These rocks might have formed from sediment deposited in a lake or a larger Hellas-filling sea.

Location near: 28.0oS, 285.4oW Image width: width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Spring

2005-01-01

444

Detecting the presence of microorganisms  

NASA Technical Reports Server (NTRS)

The presence of microorganisms in a sample is determined by culturing microorganisms in a growth medium which is in contact with a measuring electrode and a reference electrode and detecting a change in potential between the electrodes caused by the presence of the microorganisms in the medium with a high impedance potentiometer.

Wilkins, Judd R. (Inventor); Stoner, Glenn E. (Inventor)

1977-01-01

445

Double Layers in Astrophysics  

NASA Technical Reports Server (NTRS)

Topics addressed include: laboratory double layers; ion-acoustic double layers; pumping potential wells; ion phase-space vortices; weak double layers; electric fields and double layers in plasmas; auroral double layers; double layer formation in a plasma; beamed emission from gamma-ray burst source; double layers and extragalactic jets; and electric potential between plasma sheet clouds.

Williams, Alton C. (editor); Moorehead, Tauna W. (editor)

1987-01-01

446

Multifunctional layered magnetic composites.  

PubMed

A fabrication method of a multifunctional hybrid material is achieved by using the insoluble organic nacre matrix of the Haliotis laevigata shell infiltrated with gelatin as a confined reaction environment. Inside this organic scaffold magnetite nanoparticles (MNPs) are synthesized. The amount of MNPs can be controlled through the synthesis protocol therefore mineral loadings starting from 15 wt % up to 65 wt % can be realized. The demineralized organic nacre matrix is characterized by small-angle and very-small-angle neutron scattering (SANS and VSANS) showing an unchanged organic matrix structure after demineralization compared to the original mineralized nacre reference. Light microscopy and confocal laser scanning microscopy studies of stained samples show the presence of insoluble proteins at the chitin surface but not between the chitin layers. Successful and homogeneous gelatin infiltration in between the chitin layers can be shown. The hybrid material is characterized by TEM and shows a layered structure filled with MNPs with a size of around 10 nm. Magnetic analysis of the material demonstrates superparamagnetic behavior as characteristic for the particle size. Simulation studies show the potential of collagen and chitin to act as nucleators, where there is a slight preference of chitin over collagen as a nucleator for magnetite. Colloidal-probe AFM measurements demonstrate that introduction of a ferrogel into the chitin matrix leads to a certain increase in the stiffness of the composite material. PMID:25671158

Siglreitmeier, Maria; Wu, Baohu; Kollmann, Tina; Neubauer, Martin; Nagy, Gergely; Schwahn, Dietmar; Pipich, Vitaliy; Faivre, Damien; Zahn, Dirk; Fery, Andreas; Cölfen, Helmut

2015-01-01

447

Multifunctional layered magnetic composites  

PubMed Central

Summary A fabrication method of a multifunctional hybrid material is achieved by using the insoluble organic nacre matrix of the Haliotis laevigata shell infiltrated with gelatin as a confined reaction environment. Inside this organic scaffold magnetite nanoparticles (MNPs) are synthesized. The amount of MNPs can be controlled through the synthesis protocol therefore mineral loadings starting from 15 wt % up to 65 wt % can be realized. The demineralized organic nacre matrix is characterized by small-angle and very-small-angle neutron scattering (SANS and VSANS) showing an unchanged organic matrix structure after demineralization compared to the original mineralized nacre reference. Light microscopy and confocal laser scanning microscopy studies of stained samples show the presence of insoluble proteins at the chitin surface but not between the chitin layers. Successful and homogeneous gelatin infiltration in between the chitin layers can be shown. The hybrid material is characterized by TEM and shows a layered structure filled with MNPs with a size of around 10 nm. Magnetic analysis of the material demonstrates superparamagnetic behavior as characteristic for the particle size. Simulation studies show the potential of collagen and chitin to act as nucleators, where there is a slight preference of chitin over collagen as a nucleator for magnetite. Colloidal-probe AFM measurements demonstrate that introduction of a ferrogel into the chitin matrix leads to a certain increase in the stiffness of the composite material. PMID:25671158

Siglreitmeier, Maria; Wu, Baohu; Kollmann, Tina; Neubauer, Martin; Nagy, Gergely; Schwahn, Dietmar; Pipich, Vitaliy; Faivre, Damien; Zahn, Dirk; Fery, Andreas

2015-01-01

448

CHRISTINE FROST STRUCTURAL DYNAMICS  

E-print Network

Pine Wood 2 ­ 4x5x1/8 slats 2 ­ 8x1x3/4 columns 1 ­ 3x1x1/4 beam Terrarium 12x10x6 Gorilla Glue secured between the two wall panels using Gorilla Glue. The beam spanned the gap between the two columns

Ervin, Elizabeth K.

449

Perceptual presence without counterfactual richness.  

PubMed

In this commentary, I suggest that non-visual perceptual modalities provide counterexamples to Seth's claim that perceptual presence depends on counterfactual richness. Then I suggest a modification to Seth's view that is not vulnerable to these counterexamples. PMID:24739124

Madary, Michael

2014-01-01

450

TRANSPORT LAYER INTRODUCTION  

E-print Network

T TRANSPORT LAYER INTRODUCTION The Internet has evolved into an extremely large complex system of the Internet is carried out in a modular way, where each main functional module is called a ``layer.'' One of the layering structures often used is the five-layer model con- sisting of the physical layer, the link layer

Chiang, Mung

451

Display and Presence Disparity in Mixed Presence Groupware  

Microsoft Academic Search

Mixed Presence Groupware (MPG) supports both co- located and distributed participants working over a shared visual workspace. It does this by connecting multiple single-display groupware workspaces together through a shared data structure. Our implementation and observations of MPG systems exposes two problems. The first is display disparity, where connecting heterogeneous tabletop and vertical displays introduces issues in how one seats

Anthony Tang; Michael Boyle; Saul Greenberg

1996-01-01

452

Ion-acoustic double layers  

Microsoft Academic Search

The formation of plasma double layers in the presence of ion-acoustic instabilities is investigated. One-dimensional particle simulations were performed for system lengths 1024, 512, 256, and 128 times the initial electron Debye length and an electron drift speed equal to 0.6 times the electron thermal speed. Simulated electron and ion phase-space distributions, electron