WorldWideScience
1

Frost susceptibility of granular subbase materials contaminated by deicing chemicals  

DEFF Research Database (Denmark)

The increase in urban population in arctic areas leads to an increased demand for transportation infrastructures (such as roads and airfields) in the regions. This challenges the road constructions in terms of condition, bearing capacity and maintenance. It is believed that deicing agents used on roads and airfields enter the granular subbase materials and thereby makes the soil more frost-susceptible. In this project a series of isothermal frost heave tests has been carried out on granular subbase material from the runway at Kuujjuaq Airport, Que?bec, Canada. The tests have been carried out in order to determine the frost susceptibility of the material when it is contaminated by a deicing agent. Two series of three freezing tests with isothermal cooling has been conducted using identical saline gradient added through brine. Two types of cooling ramp, an automatic cooling and a manual cooling, were used in order to determine any influence from the cooling ramp. The tests included settings that allowed the samples additional brine during freezing. Hence, the water and salinity were measured before and after the tests in order to determine the redistribution of water and salinity. The test results do not support the theory that a saline gradient effectively can replace a thermal gradient and create favorable conditions for frost heave. There was no evidence of ice segregation during the tests. During freezing, heave of maximum 0.02 % was observed which, however, is not considered to be caused by ice segregation, but rather a volume increase by fusion caused by a small amount of pore water. The direction of the frost front could not be determined from the collected test results, and no reduction in bearing capacity or increase in frost susceptibility can be derived from the collected data on the granular subbase material. © 2013 American Society of Civil Engineers.

JØrgensen, Anders Stuhr; Orlander, Tobias

2013-01-01

2

Morphogenesis of Soils Associated With Frost Boils  

Science.gov (United States)

Frost boils are a kind of nonsorted circles commonly found in arctic and alpine regions. In early studies of the Northern Alaska Arctic Coastal Plain, frost boils were found more frequently on moist nonacidic tundra (MNT) than on moist acidic tundra (MAT). But a recent study indicates that frost boils are widespread on both land cover types. Although MNT has more frost boils with mineral soils exposed forming an easily recognizable circle that is generally free of vegetation (mud boils). Crossing the transition from MNT to MAT, there is increased vegetation cover on frost boils. In well-developed MAT, vegetation cover masks frost boils. Once the vegetation cover is removed, frost boils are clearly defined by ice ring ridges underneath the inter boil moss layer. These frost boils are active as indicated by chunks of cotton grass (Eriophorum vaginatum) in various stage of decomposition that are found frost churned in along the slopes of the ice ridges toward the upper permafrost. In the lower active layer and the upper permafrost there are concentrations of frost churned organic matter mixed with gleyed mineral horizons. Thus, frost boil process can be regarded as the controlling factor in the sequestration of surface produced organic matter through its incorporation into the upper permafrost for both MNT and MAT. There are drainage differences due to micro relief across the frost boil sequence. In summer, the elevated center of the frost boil is moderately well drained as compared with the poorly drained inter boil due to its depression position. The active layer depth in the center of the frost boil is generally more than twice that of the inter boil, thus the permafrost table surface forms a nearly perfect bowl shape. The lower active layer has strongly developed reticular cryogenic structure. The upper permafrost is ice-rich, generally containing more than 65% ice (vol.) and has ataxitic cryogenic structure. The thickness of the ice-rich layers in the ridges beneath the inter boil area is much greater than that beneath the boil center. In addition, the cracks and the ice veins are parallel to the slope of the ice ridge. Although there are different theories regarding the initiation of frost boils and different factors are involved in frost boil self-organization, morphological evidence in the field suggests that the thick ice formation under the inter boil causes long-term heave of the frost boil and forms its shape.

Ping, C.; Michaelson, G. J.; Kimble, J. M.; Shur, Y. L.; Walker, D. A.

2002-12-01

3

Importance of soil frost and winter climate for dissolved organic carbon (DOC) in northern boreal soils  

Science.gov (United States)

In many northern latitude regions, riparian soils are significant sources of DOC to the adjacent streams and exert a major control on stream water chemistry. As the winter climate in northern regions is predicted to be particularly affected by climate change, it is important to investigate the sensitivity of DOC in riparian soils. We conducted an eight year field-scale soil frost manipulation experiment (deep soil frost, shallow soil frost and control) to investigate the impacts of soil frost and winter conditions on the concentration and quality of DOC in riparian soil water in a boreal forest of northern Sweden. The effect of soil freezing on DOC was further investigated in a laboratory experiment on the riparian soil samples. In the laboratory experiment, we studied several combinations of four freezing related factors: low experiment temperature, water content, experiment duration and frequency of freeze-thaw cycles. Deeper and longer soil frost significantly increased the soil water DOC concentrations (up to twice) and lability in the upper soil horizons, compared to shallower and shorter soil frost. In the laboratory experiment, similar responses of soil water DOC were observed in which the highest concentration and lability were observed in the samples incubated in the lowest temperatures (-12°C). Furthermore, fungal growth rate and soil basal respiration responded positively to soil frost induced increase in DOC concentration. The frequency of freeze-thaw cycle did not appear to be an influential factor in the laboratory experiment. Several significant interactions of the factors were also detected. In addition, we studied the alterations in soil water DOC concentrations as the soil frost expanded downwards in a mire profile during the soil frost season (Nov-May). As the soil frost deepened from Nov to Feb, the soil water DOC concentrations below the ice increased. At soil frost thaw in May, the DOC concentrations decreased to the initial levels measured at the onset of soil frost formation. In a complementary freeze-out experiment in the laboratory, we observed that DOC concentrations in the unfrozen water enhanced as the frozen proportion of the sample increased, so that the DOC concentrations doubled when 75% of the sample was frozen. Here we highlight the importance of soil frost regime and winter climatic conditions for regulating DOC in riparian forest soils and in mires in seasonally frozen soils. However, to assess the sensitivity of soil DOC to climate change, the complex interactions of air temperature, snow depth and soil frost together with changes in hydrology and soil microbial community should be taken into account.

Haei, M.; Öquist, M.; Laudon, H.

2011-12-01

4

Significance of frost action and surface soil characteristics to wind erosion at Rocky Flats, Colorado. Third progress report, October 1, 1976--June 30, 1977  

Energy Technology Data Exchange (ETDEWEB)

This report summarizes information on soil frost effects collected on Rocky Flats during the 1976 and 1977 winter. The work has continued on two scales as in the previous two winters. Empirical surveys along 4 line transects during the second half of the winter support earlier conclusions that the frost susceptibility of the Rocky Flats soils is well keyed to topography. This has been used in testing a mapping procedure for potential soil frost activity in the entire Rocky Flats area. Instrumental records of weather and soil conditions have been maintained throughout the winter at the Lindsay Ranch study site, northwest of the Rocky Flats Plant. During the winter, 9 frost heave events have been recorded and are described here. This represents a low frequency of soil disturbance by frost and is accounted for by the drought conditions on the Colorado Piedmont during 1976 and 1977. Even the events which occurred were of relatively slight magnitude, a further reflection of the lack of soil moisture during the period.

Caine, N.; Morin, P.; Nicholas, R.M.

1977-01-01

5

Soils and frost boil ecosystems across the North American Arctic Transect  

Science.gov (United States)

We studied soil properties of frost boils at nine zonal-vegetation locations across the North American Arctic Transect (NAAT) in order to better understand arctic soils and their interaction with other biogeophysical components of frost boil ecosystems. Soil genetic horizons were analyzed for particle size, pH, electrical conductivity, total organic carbon (OC) and nitrogen (N), bulk density and volumetric water content. Surface soils (0-5 cm) across frost boil patterns were analyzed for of pH, OC, water content, extractable N and P, and exchangeable K, Ca and Na. Our results revealed that soil texture, pH, EC, P, Na and Ca contents are strongly influenced by local parent materials. Soil pH was acidic in the north going to alkaline in the midtransect and then again back to acidic in the south. Simple correlations between soil analytical data and observed frost boil properties across the NAAT support and are consistent with the laboratory and theoretical-conceptual models of pattern ground dynamics that have been developed by others. Soil water related well to texture. Soil horizon %OC and profile OC stocks under the pattern corresponded well to biomass and frost heave, respectively. Also soil water was closely related to biomass and heave. Nutrients in surface soils at sites corresponded to OC stocks. An interaction between soil water and segregation of Na and Ca between the pattern and interpattern was found for locations with high cation availability. At these sites, chemical as well as physical disruption of the pattern area could affect plant establishment. Overall there was a good linkage between properties relating to frost boil pattern dynamics and soil biogeochemical properties. Our study offers insight into the important process of cryoturbation for carbon sequestration in Gelisols across the Arctic.

Michaelson, G. J.; Ping, C. L.; Epstein, H.; Kimble, J. M.; Walker, D. A.

2008-09-01

6

Two-dimensional model of coupled heat and moisture transport in frost-heaving soils  

International Nuclear Information System (INIS)

A two-dimensional model of coupled heat and moisture flow in frost-heaving soils is developed based upon well known equations of heat and moisture flow in soils. Numerical solution is by the nodal domain integration method which includes the integrated finite difference and the Galerkin finite element methods. Solution of the phase change process is approximated by an isothermal approach and phenomenological equations are assumed for processes occurring in freezing or thawing zones. The model has been verified against experimental one-dimensional freezing soil column data and experimental two-dimensional soil thawing tank data as well as two-dimensional soil seepage data. The model has been applied to several simple but useful field problems such as roadway embankment freezing and frost heaving

7

Algal colonization of deglaciated and frost heaved soils in the Abisko region (subarctic Sweden).  

Czech Academy of Sciences Publication Activity Database

Strasbourgh : CAREX Project Office, European Science Foundation, 2009, s. 28-29. [Identification of Model Ecosystems in Extreme Environments. Sant Feliu de Guixoles (ES), 30.11.2008-02.12.2008] R&D Projects: GA MŠk ME 945; GA MŠk ME 934; GA MŠk LA341 Grant ostatní: The Royal Swedish Academy of Sciences(SE) FP6 506004 Institutional research plan: CEZ:AV0Z60660521; CEZ:AV0Z60050516 Keywords : algal colonization * deglaciated and frost heaved soils * Abisko region Subject RIV: EH - Ecology, Behaviour

Lukešová, Alena; Elster, Josef; Vá?a, J.; Štursová, H.

8

Effects of freezing on soil temperature, frost propagation and moisture redistribution in peat: laboratory investigations  

Directory of Open Access Journals (Sweden)

Full Text Available The effects of freezing on soil temperature and water movement were monitored in four peat Mesocosms subjected to bidirectional freezing. Temperature gradients were applied by bringing the Mesocosm tops in contact with sub-zero air temperature while maintaining a continuously frozen layer at the bottom (proxy permafrost. Soil water movement towards the freezing front (from warmer to colder regions was inferred from soil freezing curves and from the total water content of frozen core samples collected at the end of freezing cycle. This study illustrates how differences in initial water content influence the hydrologic functions of active layer in permafrost terrains covered with thick peat during soil freezing. A substantial amount of water, enough to raise the upper surface of frozen saturated soil within 15 cm of the soil surface at the end of freezing period, appeared to have moved upwards during freezing. Effects of temperature on soil matric potential, at least in the initial freezing period, appear to drive such movement as seen from analysis of soil freezing curves. Vapour movement from warmer to colder regions also appears to contribute in moisture movement. Frost propagation is controlled by latent heat for a long time during freezing. A simple conceptual model describing freezing of an organic active layer initially resembling a variable moisture landscape is proposed based upon the results of this study. The results of this study will help in understanding, and ultimately forecasting, the hydrologic response of wetland-dominated terrain underlain by discontinuous permafrost.

R. M. Nagare

2011-05-01

9

Snow depth, soil frost and nutrient loss in a northern hardwood forest  

Science.gov (United States)

We have initiated a long-term experiment to examine the consequences of decreases in snowpack accumulation at the Hubbard Brook Experimental Forest (HBEF), a northern hardwood dominated forest located in the White Mountains of New Hampshire. We are quantifying the effects of decreases in snowpack accumulation on root dynamics of two key tree species in this forest (sugar maple, yellow birch), microbial biomass and activity, NOcation loss, the acid-base chemistry of drainage water, and soil-atmosphere trace gas fluxes. We are calibrating an existing model (SNTHERM) to depict snow depth and soil frost dynamics given past or future climate scenarios for our site. In this paper, we describe the methods we are using for the manipulation studies that began in the winter of 1997/1998 and present preliminary results from our first full year of treatment. Results from our methods development efforts show that it is possible to keep plots snow free by shovelling without disturbing the forest floor. Preliminary test plot work showed that the SNTHERM model is capable of depicting snow depth and soil temperatures in both control and manipulated plots at our site. Results from our first full year of treatment showed that a relatively mild freezing event induced significant increases in nitrogen (N) mineralization and nitrification rates, solute leaching and soil nitrous oxide production and caused significant decreases in soil methane uptake. These results suggest that soil freezing events may be major regulators of soil biogeochemical processes and solute delivery to streams in forested watersheds.

Groffman, Peter M.; Hardy, Janet P.; Nolan, Scott; Fitzhugh, Ross D.; Driscoll, Charles T.; Fahey, Timothy J.

1999-10-01

10

Significance of frost action and surface soil characteristics to wind erosion at Rocky Flats, Colorado. Final report  

Energy Technology Data Exchange (ETDEWEB)

This study of the potential links between soil freezing and wind erosion was conducted at Rocky Flats during 4 winters. Most of the study has involved the conditions leading to the growth of segregation ice in the surface soil and the ground heave which that produces. This occurs about 15 times in the average winter at Rocky Flats, always on a diurnal cycle. Such frost action is preferentially distributed in time and space and cannot be estimated from air temperatures alone. November and March are the months of most frequent frost heave, and then only in the days following precipitation or snowmelt. The most marked frost effects are found on exposed interfluve and hillcrest situations, where there are patches of bare soil. Almost no effects are found on the valley floors. Soil disturbance by segregation ice leads to a marked decrease in soil bulk density, and presumably in soil strength though this change has not been quantitatively defined. However, this does not lead to wind erosion of the soil at the study site because that surface is more influenced by the vegetation cover than by the soil characteristics.

Caine, N.

1978-09-01

11

A preliminary synoptic assessment of soil frost on Marion Island and the possible consequences of climate change in a maritime sub-Antarctic environment  

Directory of Open Access Journals (Sweden)

Full Text Available Located in the sub-Antarctic, Marion Island (46° 54? S, 37° 45? E has a distinct periglacial environment that is sensitive to climate change. Diurnal soil frost is the most important geomorphic process occurring on the island and this paper aims to understand the synoptic weather circulation pattern associated with summer soil frost occurrence in a sub-Antarctic environment. Preliminary results from automated microclimate measurements in the interior of Marion Island show that summer soil frost is dependent on Antarctic air mass circulation. This occurs exclusively during post-cyclonic airflow after the passage of a cold front connected to a mid-latitudinal cyclone and subsequent ridging in of the South Atlantic Anticyclone behind the cold front, or when a series of low pressure systems passes over the island. The duration and intensity of soil frost cycles are dependent on the duration of post-cyclonic Antarctic air mass circulation. Summer soil frost on Marion Island is driven by a complex interaction between the latitudinal position of the passing cyclone, the latitudinal position of the ridging anticyclone as well as the trajectory of the air mass circulation. The data suggest that predicted trends in synoptic climate change in the sub-Antarctic may lead to non-linear responses in soil frost dynamics.

Werner Nel

2012-03-01

12

Water relation response to soil chilling of six olive (Olea europaea L.) cultivars with different frost resistance  

Energy Technology Data Exchange (ETDEWEB)

The relationship between the water relations of six olive cultivars exposed to different soil temperatures (14 0.1, 9.9 0.1 and 5.8 0.2 degree centigrade) and their inherent frost resistance (as determined by two different methods) was investigated. Soil chilling was achieved by introducing pots of olive plants into water baths. The water relations of these plants were compared to those of plants kept under conditions of room temperature. The cultivars Frantoio, Picual and Changlot Real began to show significant dehydration below 14 degree centigrade, while Cornicabra, Arbequina and Ascolana Tenera showed this below 10 degree centigrade. This response is probably due to delayed stomatal closure. Only Cornicabra and Picual showed a significant reduction in leaf conductance (below 10 degree centigrade and 6 degree centigrade respectively). This absence of stomatal control led to a significantly greater dehydration in Ascolana Tenera. These variations in response to the soil chilling temperature suggest that different mechanisms may be at work, and indicate that would be necessary to study the influence of rootstock in the frost resistance of olive plants. The variations recorded grouped the cultivars as either resistant (Cornicabra), tolerant (Picual, Ascolana Tenera and Arbequina), or sensitive (Frantoio and Changlot Real). This classification is in line with the frost resistance reported for these cultivars in the literature, and with the results obtained in the present work using the stomatal density and ion leakage methods of determining such resistance. (Author) 40 refs.

Perez-Lopez, D.; Gijon, M. C.; Marino, J.; Moriana, A.

2010-07-01

13

Magnetic Susceptibility Measurements for in Situ Characterization of Lunar Soil  

Science.gov (United States)

Magnetic separation is a viable method for concentration of components of lunar soils and rocks for use as feedstocks for manufacture of metals, oxygen, and for recovery of volatiles such as He-3. Work with lunar materials indicates that immature soils are the best candidates for magnetic beneficiation. The magnetic susceptibility at which selected soil components such as anorthite, ilmenite, or metallic iron are separated is not affected by soil maturity, but the recovery of the concentrated components is. Increasing soil maturity lowers recovery. Mature soils contain significant amounts of glass-encased metallic iron. Magnetic susceptibility, which is sensitive to metallic iron content, can be used to measure soil maturity. The relationship between the ratio of magnetic susceptibility and iron oxide and the conventional maturity parameter, I(sub s)/FeO, ferromagnetic resonant intensity divided by iron oxide content is given. The magnetic susceptibilities were determined using apparatus designed for magnetic separation of the lunar soils.

Oder, R. R.

1992-01-01

14

Frost heaving of planted tree seedlings in the boreal forest of northern Sweden  

Energy Technology Data Exchange (ETDEWEB)

Frost heaving can be a leading cause of tree seedling mortality in many places in the boreal forest of Northern Sweden. The aim of this investigation was to improve our understanding of frost heaving of planted tree seedlings as related to snow cover, scarification, planting methods and soil types. The thesis is based on a review paper, three field experiments and one laboratory experiment. The experiments focus on different methods to control frost heaving of forest tree seedlings and on a number of factors affecting the extent of frost heaving. The review paper identifies the many aspects of frost heaving of forest tree seedlings and agricultural crops based on an intensive review of the research contributions made during the last century. Even if many investigations have been carried out with the aim to decrease the extent of frost heaving, very little quantitative results are available for tree seedlings. In a field experiment, the choice of planting positions was effective in decreasing frost heaving of planted seedlings following mounding or disc-trenching. Seedlings planted in the depressions were largely affected by frost heaving with a maximal vertical displacement of 5.4 cm while frost heaving did not occur on the top of the mound. On the other hand, the planting time and planting depth had no influence on the extent of frost heaving. In another field experiment the size of the scarified patches was strongly correlated to frost heaving which reached between 7.6 and 11.5 cm in 4 and 8-dm patches compared to between 4.4 and 5.3 in non-scarified soil and in a 1-dm patch. Ground vegetation probably decreases the diurnal temperature variation and the number of freezing-thawing cycles. The duration and magnitude of frost temperatures, the frost hour sum, increased with patch size. The difference between the 8-dm and 1-dm patch increased to 2064 hour-degrees at the end of the winter. In larger patches, the planting depth seemed to be effective in reducing the maximum frost heaving of the seedlings. In the third field experiment snow cover also showed to be an important factor in regard to frost heaving of tree seedlings. In a snow-free treatment combined with soil scarification, an uplift of 14.6 cm was measured during a winter season. In contrast no vertical displacement was observed under a simulated snow cover. The strong influence of snow on the extent of frost heaving indicates that further investigation should be focused on the interaction between maximum frost heaving and snow depth. In the laboratory freezing chamber experiment it was demonstrated that soil from spodic B horizon is less susceptible to frost heaving than soil from E horizon. Needle ice did not grow at all on soil samples from E horizon during a 3-day test, neither on fresh, nor on oven dried samples. On fresh samples of soil from Bs horizon, needle ices reached a maximum height of 9.7 cm in average. The use of theodolite and wooden dowels to estimate the extent of frost heaving in this study allowed to follow the process during the frost heaving period. A vertical uplift in millimetres could be recorded. A development of reliable measuring methods which allow a continuous estimation of the extent of frost heaving damage during the whole process, would undoubtedly represent an important step towards a better understanding of frost heaving of tree seedlings.

Goulet, France

2000-07-01

15

Frost heaving of planted tree seedlings in the boreal forest of northern Sweden  

International Nuclear Information System (INIS)

Frost heaving can be a leading cause of tree seedling mortality in many places in the boreal forest of Northern Sweden. The aim of this investigation was to improve our understanding of frost heaving of planted tree seedlings as related to snow cover, scarification, planting methods and soil types. The thesis is based on a review paper, three field experiments and one laboratory experiment. The experiments focus on different methods to control frost heaving of forest tree seedlings and on a number of factors affecting the extent of frost heaving. The review paper identifies the many aspects of frost heaving of forest tree seedlings and agricultural crops based on an intensive review of the research contributions made during the last century. Even if many investigations have been carried out with the aim to decrease the extent of frost heaving, very little quantitative results are available for tree seedlings. In a field experiment, the choice of planting positions was effective in decreasing frost heaving of planted seedlings following mounding or disc-trenching. Seedlings planted in the depressions were largely affected by frost heaving with a maximal vertical displacement of 5.4 cm while frost heaving did not occur on the top of the mound. On the other hand, the planting time and planting depth had no influence on the extent of frost heaving. In another field experiment the size of the scarified patches was strongly correlated to frost heaving which reached between 7.6 and 11.5 cm in 4 and 8-dm patches compared to between 4.4 and 5.3 in non-scarified soil and in a 1-dm patch. Ground vegetation probably decreases the diurnal temperature variation and the number of freezing-thawing cycles. The duration and magnitude of frost temperatures, the frost hour sum, increased with patch size. The difference between the 8-dm and 1-dm patch increased to 2064 hour-degrees at the end of the winter. In larger patches, the planting depth seemed to be effective in reducing the maximum frost heaving of the seedlings. In the third field experiment snow cover also showed to be an important factor in regard to frost heaving of tree seedlings. In a snow-free treatment combined with soil scarification, an uplift of 14.6 cm was measured during a winter season. In contrast no vertical displacement was observed under a simulated snow cover. The strong influence of snow on the extent of frost heaving indicates that further investigation should be focused on the interaction between maximum frost heaving and snow depth. In the laboratory freezing chamber experiment it was demonstrated that soil from spodic B horizon is less susceptible to frost heaving than soil from E horizon. Needle ice did not grow at all on soil samples from E horizon during a 3-day test, neither on fresh, nor on oven dried samples. On fresh samples of soil from Bs horizon, needle ices reached a maximum height of 9.7 cm in average. The use of theodolite and wooden dowels to estimate the extent of frost heaving in this study allowed to follow the process during the frost heaving period. A vertical uplift in millimetres could be recorded. A development of reliable measuring methods which allow a continuous estimation of the extent of frost heaving damage during the whole process, would undoubtedly represent an important step towards a better understanding of frost heaving of tree seedlings

16

Frost-ring chronologies as dendroclimatic proxies of boreal environments  

Science.gov (United States)

Frost rings are formed in tree stems when growing-season frosts affect immature wood cells, producing collapsed cells within annual tree rings. Open boreal forests are most susceptible to record growing-season frost because they lack the greenhouse effect commonly observed in closed forests. Here we present a novel method to construct regional frost-ring chronologies in lichen-black spruce woodlands of the boreal forest zone. Because the ability of trees to form frost rings depends on several factors (including bark thickness and ring width), we used two models to produce a Frost Composite Index based on a frost susceptibility window of cambial age <30 years. The frost-ring chronology showed alternating periods of high and low frost activity that were highly consistent within and among sites. Reconstruction of growing-season frost activity may be used as dendroclimatic proxies of climate variability and may give insights into future risks of frost damage in a warming climate.

Payette, Serge; Delwaide, Ann; Simard, Martin

2010-01-01

17

Non-stationary temporal characterization of the temperature profile of a soil exposed to frost in south-eastern Canada  

Directory of Open Access Journals (Sweden)

Full Text Available The objective of this work was to compare time and frequency fluctuations of air and soil temperatures (2-, 5-, 10-, 20- and 50-cm below the soil surface using the continuous wavelet transform, with a particular emphasis on the daily cycle. The analysis of wavelet power spectra and cross power spectra provided detailed non-stationary accounts with respect to frequencies (or periods and to time of the structure of the data and also of the relationships that exist between time series. For this particular application to the temperature profile of a soil exposed to frost, both the air temperature and the 2-cm depth soil temperature time series exhibited a dominant power peak at 1-d periodicity, prominent from spring to autumn. This feature was gradually damped as it propagated deeper into the soil and was weak for the 20-cm depth. Influence of the incoming solar radiation was also revealed in the wavelet power spectra analysis by a weaker intensity of the 1-d peak. The principal divergence between air and soil temperatures, besides damping, occurred in winter from the latent heat release associated to the freezing of the soil water and the insulation effect of snowpack that cease the dependence of the soil temperature to the air temperature. Attenuation and phase-shifting of the 1-d periodicity could be quantified through scale-averaged power spectra and time-lag estimations. Air temperature variance was only partly transferred to the 2-cm soil temperature time series and much less so to the 20-cm soil depth.

F. Anctil

2008-05-01

18

Frost resistance in Salix  

Energy Technology Data Exchange (ETDEWEB)

This thesis presents results from a series of studies in various aspects of frost hardiness in Salix viminalis and Salix dasyclados. The seasonal development of frost resistance and the processes which lead to frost damage under different environmental and laboratory test conditions are elucidated, and current methods to evaluate plant response to temperature stress are developed further. A number of phases in the seasonal development of frost resistance can be distinguished, in which the susceptibility of plants to frost ranges from low (dormant stage) to high (growth stage). Changes in phenological characters, ultrastructural cell features, activity of the vascular cambium and storage products (starch, proteins) are correlated with the changes in frost resistance during the annual growth cycle. Differences in relative growth rates imposed by nutrient conditions also affected onset time and rate of frost hardiness development and deacclimation and onset of growth during spring. Dormant stem cutting of various Salix species and clones collected outdoors during winter or subjected to a standardized artificial hardening regime at -4 degrees C survived exposure to at least 85 degrees C. The presence of ice on wintering shoots will restrict freezing avoidance of shoot to above -4 degrees C. Early formation of extracellular ice at -1 degrees C to -4 degrees C, followed by associated high tolerance to freeze-induced dehydration, was concluded to be an important survival mechanism for all winter-dormant Salix plant. Salix species have the inherent ability to develop adequate tolerance to the low winter temperatures in Scandinavian conditions. 304 refs, 8 figs, 11 tabs

Fircks, H.A. von

1994-12-31

19

Frost evolution in tailings  

International Nuclear Information System (INIS)

A review was carried out on the physical and thermal mechanisms of permafrost evaluation in soils and uranium tailings. The primary mechanism controlling permafrost evolution is conductive heat transfer with the latent heat of fusion of water being liberated as phase change occurs. Depending on the soil properties and freezing rate, pore water can be expelled from the frost front or pore water can migrate towards the frost front. Solute redistribution may occur as the frost front penetrates into the soil. The rate of frost penetration is a function of the thermal properties of the tailings and the climatic conditions. Computer modelling programmes capable of modelling permafrost evolution were reviewed. The GEOTHERM programme was selected as being the most appropriate for this study. The GEOTHERM programme uses the finite element method of thermal analysis. The ground surface temperature is determined by solving the energy balance equations a the ground surface. The GEOTHERM programme was used to simulate the permafrost evolution in the Key Lake Mine tailings located in north central Saskatchewan. The analyses indicated that the existing frozen zones in the tailing pond will eventually thaw if an average snow depth covers the tailings. Hundreds of years are required to thaw the tailings. If minimal snow cover is present the extent of the frozen zone in the tailings will increase

20

Effect of soil frost on growing season nitrogen uptake by fine roots of mature trees in northern hardwood forests of the United States  

Science.gov (United States)

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

21

Soil susceptibility to acidification; 1 : 1 000 000  

International Nuclear Information System (INIS)

The capacity of soils to resist to acidification depends on the content of carbonates, humus, clayey minerals, and salts. The least prone to acidification are the carbonate and alkaline soils where the pH does not significantly change (the carbonate controlling system). The soils pertaining to different soil units (carbonate Chernozems, Histi-Mollic Gleysols, Fluvisols, Rendzinas, Solonchals and Solonetzs) are in this group. On the other side, there are the very washed out (leached) soils of mountain areas where pH does not change significantly due to their extreme acidity (aluminium controlling system). Four classes of soils with different susceptibility to acidification depending on their buffer capacities controlled by the content of clay, humus and basic ions are classified into this group. Very sensitive (prone to acidification) are the light sandy soils with low content of humus and clay where pH in slightly acid to neutral areas is maintained by calcification and fertilisation. (author)

22

Assessment of soil erosion susceptibility using empirical modeling  

Science.gov (United States)

Soil erosion is one of the most serious land degradation problems all over the world, causing irreversible land quality reduction. In this paper, we modify the Revised Universal Soil Loss Equation (RUSLE) model by replacing the factors of slope length and gradient with Sediment Transport Index (STI). The Digital Elevation Model, terrain parameters, Normalized Difference Vegetation Index (NDVI), and rainfall data are used as inputs to the model. Along with the application of remote sensing techniques and ground survey measurements, erosion susceptibility maps are produced. The revised models are then used to obtain the optimal estimate of soil erosion susceptibility at Alianello of southern Italy, which is prone to soil erosion. The soil loss estimated from the modified RUSLE model shows a large spatial variance, ranging from 10 to as much as 7000 ton ha-1 yr-1. The high erosion susceptible area constitutes about 46.8% of the total erosion area, and when classified by land cover type, 33% is "mixed bare with shrubs and grass", followed by 5.29% of "mixture of shrubs and trees", with "shrubs" having the lowest percentage of 0.06%. In terms of slope types, very steep slope accounts for a total of 40.90% and belongs to high susceptibility, whereas flat slope accounts for only 0.12%, indicating that flat topography has little effect on the erosion hazard. As far as the geomorphologic types are concerned, the type of "moderate steep-steep slopes with moderate to severe erosion" is most favorable to high soil erosion, which comprises about 9.34%. Finally, we validate the soil erosion map from the adapted RUSLE model against the visual interpretation map, and find a similarity degree of 71.9%, reflecting the efficiency of the adapted RUSLE model in mapping the soil erosion in this study area.

Guo, Jianping; Niu, Tao; Rahimy, Pooyan; Wang, Fu; Zhao, Haiying; Zhang, Jiahua

2013-02-01

23

Reduction in soil loss from erosion-susceptible soils amended with humic substances from oxidized coal  

International Nuclear Information System (INIS)

Soils that pose high risk of erosion require amendment with either natural or synthetic soil conditioners to reduce soil loss hazards. The objective of this study was to evaluate the potential of using coal-derived humic substances (as soil conditioners) to reduce runoff erosion on erosion-susceptible soils. Surface samples of severely degraded soils from Principina in Tuscany and Bovolone in Venice in Italy were used to assess the effects of five rates (0, 0.05, 0.01, 0.50 and 1.00 g/kg) of humic acids (HA) on soil loss and other hydrological parameters. The results showed that amending erosion-susceptible soils with low rates of coal-derived humic substances is a potentially effective soil management practice for reducing erosion rates

24

Magnetic susceptibility mapping of soil pollution  

International Nuclear Information System (INIS)

Fast and cost-effective detection of industrial pollution can significantly promote its ecological, economic and social assesment. A magnetometric method, used for qualitative determination of anthropogenic contamination, meets these requirements but needs further development in more quantitative terms.lt could be used successfully in numerous cases when heavy metals coexists with strongly magnetic iron oxide particles in the source dust. We presented a magnetic study which examines the utility of magnetometric techniques for rapid, qualitative detection of metallic pollutants in soils. In the present paper we tested the use of rock-magnetic method designed to access the degree of pollution of soil taken from Novaky situated in the south-western of Slovakia. The aim was to identify magnetic particles and to link magnetic pollution, to trace distribution and concentration of contaminants in soil. About 40 years the rainwater overflow the dump and flooded out the ash waste from the brown coal power plant in Novaky. Soil samples have been taken from 3 horizons (20, 40 and 60 cm) and measured by KLY-kappabridge in the Slovak Academy of Sciences, in Geophysical Institute in Bratislava. Our results clearly demonstrate that magnetic anomalies can be explained by human activity. (authors)

25

Investigation of effects of moisture on soil temperature regimes and frost depth in a laboratory model  

OpenAIRE

Freezing depth is one the most important climatic parameters for indices applied in various fields such as agriculture and civil engineering. The parameter of freezing depth depends on different factors including astronomical, surface air temperature, humidity; soil characteristics such as texture, heat capacity, thermal conductivity and specific heat. This study investigated the effect of air temperature on freezing depth. Apparatus able to reach temperatures of -16 ?C was set up to test so...

Et Al, Rahnama Yami E.

2012-01-01

26

Robert Frost on Writing.  

Science.gov (United States)

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

27

Frost formation and ice adhesion on superhydrophobic surfaces  

OpenAIRE

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 textures without any particular spatial preference. Ice adhesion measurements on superhydrophobic surfaces susceptible to frost formation show increased adhesion over smooth surfaces with a strong linear trend with the total surface area. These studies indicate that frost for...

Varanasi, Kripa K.; Deng, Tao; Hsu, Ming; Bhate, Nitin; Smith, Jonathan David

2010-01-01

28

Seasonal Frost in Terra Sirenum  

Science.gov (United States)

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

29

Magnetic Susceptibility of Soils and Different Kinds of Forests  

Science.gov (United States)

The aim of the research was to study the influence of different tree stands on top- soil magnetic susceptibility. The study was performed in old park in Prohonice (near Prague) in Czech Republic. On the relatively small area of Prohonice Park, five dif- ferent coniferous tree species (pine, spruce, blue spruce, fir, Douglas fir) and five of deciduous species (beech, red oak, common oak, hornbeam, birch) were found, grow- ing in small clusters on the same geological background. Also the other natural and anthropogenic factors like distance from industrial and urban sources of pollution, type of soil, climate etc. were similar. Magnetic susceptibility was measured directly in the field using ?Bartington? MS2D sensor. Twenty topsoil cores of 0,3 m long (2 under the each tree species) were collected using the Huge sampler. Magnetic sus- ceptibility of topsoil profiles was obtained using ?Bartington? MS2C sensor. The field magnetic susceptibility (MS) data are comparable to the laboratory data. The maxi- mum MS values in all profiles are observed 3 ? 5 cm below surface (Of layer). The MS values increase along the soil profile up to 5 cm of depth (reaching value 73,5*10-5 SI for Douglas fir and 33*10-5 SI for red oak) and then decrease (to about 40*10-5 SI for coniferous forest and about 20*10-5 SI for deciduous forest). The research results show that the kind of forest has the influence on the values of magnetic susceptibility. Generally higher MS values were observed in coniferous forest, but surprisingly only on the surface (Ol layer) the values of MS are lower than in deciduous forest. It could be because the measurements were done in autumn after the fall of leaves. The dust deposition on leaves causes high values of magnetic susceptibility.

Ferdyn, M.; Strzyszcz, Z.

30

Assessing Biodegradation Susceptibilities of Selected Petroleum Hydrocarbons at Contaminated Soils  

Directory of Open Access Journals (Sweden)

Full Text Available The susceptibility to biodegradation of selected saturated hydrocarbons (SHCs, polycyclic aromatichydrocarbons (PAHs and asphaltenes in a Barrow crude oil and extracts isolated from soils contaminated with theBarrow crude oil at day 0 and 39 was determined. Soil samples were contaminated with a Barrow crude oil across thesurface (5% w/w as part of a mesocosm experiment in order to mimic similar conditions in the environment. Theextent of biodegradation of the Barrow oil extracted from the contaminated soils at day 0 and day 39 was assessed byGC-MS analyses of SHCs and PAHs fractions. Changes in the relative abundances of n-alkanes (loss of low-molecularweighthydrocarbons and pristane relative to phytane (Pr/Ph and their diastereoisomers were determined. Changesin the diastereoisomer ratios of Pr and Ph relate to the decrease in abundance of the phytol-derived 6(R,10(Sisoprenoids with increasing biodegradation. The percentage change in abundances of each of selectedalkylnaphathalenes with time (day 0 to 39 was determined, enabling an order of susceptibility of their isomers tobiodegradation. It was established that the 2-methylnaphthalene isomers (2-MN is more susceptible to microbialattack than 1-MN isomer indicated by decreasing in percent abundance from day 0 to 39 for the 2-MN isomer. TheGC-MS analyses of the original Barrow oil indicated the oil had not undergone biodegradation. When this oil wasused in the soil mesocosm experiments the oil was shown to biodegrade to about a level 2 -3 based on the biodegradationsusceptibility of the various SHCs and PAHs described above

Markus Heryanto Langsa

2010-01-01

31

Soil magnetic susceptibility: A quantitative proxy of soil drainage for use in ecological restoration  

Science.gov (United States)

Flooded, saturated, or poorly drained soils are commonly anaerobic, leading to microbially induced magnetite/maghemite dissolution and decreased soil magnetic susceptibility (MS). Thus, MS is considerably higher in well-drained soils (MS typically 40-80 ?? 10-5 standard international [SI]) compared to poorly drained soils (MS typically 10-25 ?? 10-5 SI) in Illinois, other soil-forming factors being equal. Following calibration to standard soil probings, MS values can be used to rapidly and precisely delineate hydric from nonhydric soils in areas with relatively uniform parent material. Furthermore, soil MS has a moderate to strong association with individual tree species' distribution across soil moisture regimes, correlating inversely with independently reported rankings of a tree species' flood tolerance. Soil MS mapping can thus provide a simple, rapid, and quantitative means for precisely guiding reforestation with respect to plant species' adaptations to soil drainage classes. For instance, in native woodlands of east-central Illinois, Quercus alba , Prunus serotina, and Liriodendron tulipifera predominantly occur in moderately well-drained soils (MS 40-60 ?? 10-5 SI), whereas Acer saccharinum, Carya laciniosa, and Fraxinus pennsylvanica predominantly occur in poorly drained soils (MS restoration of mesic, wet mesic, and wet prairie species to pre-settlement distributions at Meadowbrook Park (Urbana, IL, U.S.A.). Through use of soil MS maps calibrated to soil drainage class and native vegetation occurrence, restoration efforts can be conducted more successfully and species distributions more accurately reconstructed at the microecosystem level. ?? 2008 Society for Ecological Restoration International.

Grimley, D.A.; Wang, J.-S.; Liebert, D.A.; Dawson, J.O.

2008-01-01

32

Frost risks in the Mantaro river basin  

Science.gov (United States)

As part of the study on the Mantaro river basin's (central Andes of Perú) current vulnerability to climate change, the temporal and spatial characteristics of frosts were analysed. These characteristics included intensity, frequency, duration, frost-free periods, area distribution and historical trends. Maps of frost risk were determined for the entire river basin, by means of mathematical algorithms and GIS (Geographic Information Systems) tools, using minimum temperature - 1960 to 2002 period, geomorphology, slope, land-use, types of soils, vegetation and life zones, emphasizing the rainy season (September to April), when the impacts of frost on agriculture are most severe. We recognized four categories of frost risks: low, moderate, high and critical. The critical risks (with a very high probability of occurrence) were related to high altitudes on the basin (altitudes higher than 3800 m a.s.l.), while the low (or null) probability of occurring risks were found in the lower zones (less than 2500 m a.s.l.). Because of the very intense agricultural activity and the high sensitivity of the main crops (Maize, potato, artichoke) in the Mantaro valley (altitudes between 3100 and 3300 m a.s.l.), moderate to high frost risks can be expected, with a low to moderate probability of occurrence. Another significant result was a positive trend of 8 days per decade in the number of frost days during the rainy season.

Trasmonte, G.; Chavez, R.; Segura, B.; Rosales, J. L.

2008-04-01

33

Effects of Parent Materials, Gypsum and Carbonates on the Magnetic Susceptibility of Soils in Southern Mashhad  

Directory of Open Access Journals (Sweden)

Full Text Available Magnetic susceptibility measurement is a simple and quick technique for characterizing soils and sediments and describing soil-forming processes. The interpretation of soil magnetic susceptibility data needs sufficient knowledge about the factors affecting this parameter. To identify the effects of parent material, gypsum and calcium carbonate equivalent, 42 samples were taken from horizons of soils developed on loessial, alluvial, granitic and marly materials in southern Mashhad. Gypsum and carbonates of soil samples were removed by successive washing with distilled water and diluted HCl, respectively. Magnetic susceptibility of bulk samples (?lfbulk, gypsum free samples (?lfGf, gypsum and carbonates free samples (?lfGCf and gypsum, carbonates and sand free samples (?lfGCSf was measured. The results revealed a strong 1:1 correlation between the measured and calculated ?lfGf and ?lfGCf. Despite the high amounts of gypsum and carbonates in soils developed on marls, their ?lfbulk was much more than that of the other soils and reached up to 121.8×10-8m3 kg-1. In contrast, the ?lfbulk values of saprolitic granite were less than 10.4×10-8m3 kg-1. The ?lfbulk values of loessial and alluvial soils were less than those of marly soils but higher than those of soils developed on saprolitic granite. ?lfbulk values were negatively correlated with the amount of sand. However, reduction in magnetic susceptibility values of marly soils after removing sand reflects the different nature of this soil. The correlation between ?lfbulk and amount of silt and clay is positive, but the magnetic susceptibility values are more sensitive to clay percentage, indicating the more important contribution of clay to magnetic susceptibility values. The results of this study highlight the role of parent materials, gypsum and carbonates in the soil magnetic susceptibility values that should be considered.

A. Karimi

2012-10-01

34

Frost heave in He  

International Nuclear Information System (INIS)

Frost heave occurs in various phenomena in natural environment. It has been studied in helium on porous glasses under perfect ice-segregation condition. The maximum frost heave pressure was investigated for various conditions and was in good agreement with the thermodynamical prediction. The dynamical properties of frost heave are discussed and some of the preliminary results of the growth rate measurement are presented. (orig.)

35

The possibilities of using magnetic susceptibility measurements for evaluating degradation of erosion affected soils.  

Czech Academy of Sciences Publication Activity Database

Bratislava : ÚH SAV, 2013 - (?elková, A.), s. 92-97 ISBN 978-80-89139-30-9. [Stav poznania vo výskume v hydrologických vedách. Smolenice (SK), 23.09.2013-25.09.2013] R&D Projects: GA MZe QJ1230319 Institutional support: RVO:67985530 Keywords : soil erosion * soil degradation * magnetic susceptibility * terrain properties Subject RIV: DF - Soil Science

Jakšík, O.; Kodešová, R.; Kapi?ka, Aleš; Dlouhá, Šárka; Bayarsaikhan, S.; Fér, M.; Klement, A.

36

Relationship between Magnetic Susceptibility and Heavy Metals Concentration in Polluted Soils of Lenjanat Region, Isfahan  

OpenAIRE

This study analyzed the relationship between soil magnetic susceptibility and the content of Cd, Cu, Ni, and Fe on 233 samples from polluted soils of Lenjanat Region in the Isfahan. The aim was to investigate the suitability of such measurements for indicating heavy metal pollution. Heavy metal contents were determined after extraction with nitric acid. Basic soil characteristics were determined using common methods. Geochemical analysis of soil samples showed close correlation between Cd, Ni...

Salehi M. H.; Sh, Jorkesh; Mohajer R.

2013-01-01

37

Frost on Utopia Planitia  

Science.gov (United States)

This Viking Lander 2 picture from Utopia Planitia shows the first clear indication of frost accumulation on the Martian surface seen by lander cameras. The picture, looking due north, was obtained with a blue filter at 12:59 p.m. local lander time, Sept. 13, 1977. The season is late winter. Frost appears as a white accumulation around the bottom of rocks, in a trench dug by the lander sampler arm, and in scattered patches on the darker surface. The shadow of the lander, including the camera (center) and the meteorology boom (left), appears in foreground. As the sun moves, the shadow is moving from left to right, exposing areas covered by frost and previously protected from the sun by the lander shadow. (Another image taken one-half hour later suggests the frost patches have become smaller.) Apparently frost, formed during the Martian night, at least partially disappears during the warmer daytime. The composition of the frost, whether carbon dioxide or water or a mixture of the two (CO2 clathrate), is not known. Measurements from the meteorology instrument indicate minimum nighttime temperatures of 160 Kelvin (-171 Fahrenheit). At the time the image was taken, the temperature had risen to 175 Kelvin (-144 Fahrenheit). The atmospheric pressure was 8.835 millibars. This combination of pressure and temperature are inconsistent with carbon dioxide frost formation, but plausible near-surface mechanisms might have resulted in conditions favorable for CO2 frost formation. Viking orbiter thermal mapping and water vapor instruments indicate temperatures might have been slightly lower than measured by the lander, suggesting that the frost is more likely CO2 than H20. A remote, but possible, explanation is that the material is an extremely bright dust deposit. Color images to be taken will be able to discount this interpretation. The mechanism for frost deposition is unknown. Possibilities include formation directly on the surface, precipitation as snow, or material blown to the area around the lander from colder regions.

1977-01-01

38

Time dependence of magnetic susceptibility of soil chronosequences on the California coast  

Science.gov (United States)

As the age of the soils in a chronosequence on the California coast increases, the difference between the magnetic susceptibility of eluvial and illuvial horizons increases, and the residual susceptibility after extraction with citrate-bicarbonate-dithionite (CBD) decreases. Enhanced susceptibility results from the conversion of nonferrimagnetic minerals to secondary ferrimagnetic forms (most likely maghemite) and the preferential accumulation of inherited and pedogenic magnetic minerals. Little enhancement occurs for pedons younger than 40,000 yr. By 124,000 yr, most of the magnetic susceptibility can be attributed to forms soluble in CBD. Magnetic susceptibility appears to vary systematically over time for three chronosequences from areas with mean annual precipitation ranging from 650 to 1500 mm yr -1. Magnetic susceptibility enhancement may be a useful parameter for estimating soil age in certain climates.

Singer, M. J.; Fine, P.; Verosub, K. L.; Chadwick, O. A.

1992-05-01

39

Performance of WEPP energy-based routine for simulating snow and soil frost in the Pacific Northwest, USA  

Science.gov (United States)

The unique winter climate of the Northwestern Wheat and Range Region (NWRR) of the Pacific Northwest USA creates a challenge for modeling snow accumulation and melt and interaction with soil freezing and thawing. The climate has sometimes been described as Mediterranean with 55 to 65 % of the annual...

40

Enhanced by Frost  

Science.gov (United States)

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

41

Polygons in Martian Frost  

Science.gov (United States)

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

42

Frost hardiness of tree species is independent of phenology and macroclimatic niche.  

Science.gov (United States)

The differences in timing in bud burst between species have been interpreted as an adaptation to late frost events in spring. Thus, it has been suggested that the degree of frost susceptibility of leaves is species-specific and depends on the species' phenology and geographic distribution range. To test for relationships between frost tolerance and phenology as well as between frost tolerance and distribution range across Central European tree species, we studied the frost hardiness of closed buds before bud burst and of freshly opened buds at the time of bud burst. We hypothesized that species with early bud burst and species distributed in eastern and northern areas were more frost tolerant than species with late bud burst and species distributed in western and southern areas. Frost hardiness was estimated by exposing twigs to 11 frost temperatures between -4 degrees Centigrade and -80 degrees Centigrade and by assessing tissue damage by the electrolyte leakage method. In contrast to our hypotheses, neither frost hardiness of closed buds nor frost hardiness of freshly opened buds were related to any variable describing species' macroclimatic niche. Furthermore, frost hardiness of freshly opened buds did not differ among species. Thus, the investigated species with early bud burst take higher risks of frost damage than the species with late bud bursts. These findings indicate that frost hardiness might not play the key role in limiting the geographic distribution ranges previously anticipated. PMID:25740149

Hofmann, M; Bruelheide, H

2015-03-01

43

Relationship between Magnetic Susceptibility and Heavy Metals Concentration in Polluted Soils of Lenjanat Region, Isfahan  

Directory of Open Access Journals (Sweden)

Full Text Available This study analyzed the relationship between soil magnetic susceptibility and the content of Cd, Cu, Ni, and Fe on 233 samples from polluted soils of Lenjanat Region in the Isfahan. The aim was to investigate the suitability of such measurements for indicating heavy metal pollution. Heavy metal contents were determined after extraction with nitric acid. Basic soil characteristics were determined using common methods. Geochemical analysis of soil samples showed close correlation between Cd, Ni and Fe. Cd concentration was the highest of all the elements studied. The correlation between the analyzed metals and magnetic susceptibility are positive and significant for Fe and Cu. Results suggests that magnetic susceptibility can be used as a guideline to find contaminated urban areas with Fe and Cu in this region.

Salehi M. H.

2013-04-01

44

Large scale magnetic susceptibility soil mapping: a proxy for geological mapping and exploration from Bogoso (Ghana)  

Science.gov (United States)

This paper describes the use of magnetic susceptibility measurements on a set of nearly 3000 soil samples (one sample per km2) collected for geochemical analyses within the framework of a geological mapping program in Ghana. The result is a map of soil magnetic susceptibility which has been compared with other maps. There is a good consistency with geological domains and lithologies, as well as with some of the geochemical soil analyses and also partly with the aeromagnetic data. In the tropical, deeply weathered lateritic context of the study area, soil magnetic susceptibility reveals similarities with magnetic and/or geochemical survey results, suggesting this rapid and easy to use technique can be an effective tool for exploration and geological mapping programs.

Théveniaut, Hervé; Clarke, Brendan

2013-01-01

45

Soil magnetic susceptibility as indicator of radioactive contamination  

International Nuclear Information System (INIS)

Measurement of magnetic susceptibility is a method, which is used in many areas of research. The locality Ak-Tjuz is typical example of old ecological load. One of the negative effects represents radioactive contamination. This situation is caused by environmental disaster in 1964. For useful reparation it is really necessary to determinate the surface range of contamination. And measurement of the magnetic susceptibility could be the suitable method for that kind of monitoring. (author)

46

Mapping soil erosion using magnetic susceptibility. A case study in Ukraine  

Directory of Open Access Journals (Sweden)

Full Text Available The intrinsic element grouping of the magnetic susceptibility (MS values is conducted. The relation between MS values and erosion index is shown. The objective of the investigation is study of the information about magnetic susceptibility of soils as a diagnostic criterion to erodibility. The investigations were conducted in the limits of Tcherkascy Tishki territory, Kharkiv district. The soils of the territory are presented by catenary row of chernozems. The study area was used in the field crop rotation. The soil conservation technologies have not been applied. The data analyze confirmed high correlation of the MS, erosive index and humus content. The possibility of MS cartogram using at the soil erodibility map is presented. The magnetic methods can be extensively used at the soil erosion investigations thanks to the speed and low cost.

P. Nazarok

2014-03-01

47

Mapping soil erosion using magnetic susceptibility. A case study in Ukraine  

Science.gov (United States)

The intrinsic element grouping of the magnetic susceptibility (MS) values is conducted. The relation between MS values and erosion index is shown. The objective of the investigation is study of the information about magnetic susceptibility of soils as a diagnostic criterion to erodibility. The investigations were conducted in the limits of Tcherkascy Tishki territory, Kharkiv district. The soils of the territory are presented by catenary row of chernozems. The study area was used in the field crop rotation. The soil conservation technologies have not been applied. The data analyze confirmed high correlation of the MS, erosive index and humus content. The possibility of MS cartogram using at the soil erodibility map is presented. The magnetic methods can be extensively used at the soil erosion investigations thanks to the speed and low cost.

Nazarok, P.; Kruglov, O.; Menshov, O.; Kutsenko, M.; Sukhorada, A.

2014-03-01

48

Soil magnetic susceptibility and contamination of soils from kindergartens areas by potentially toxic elements in Bratislava (Slovakia  

Directory of Open Access Journals (Sweden)

Full Text Available The aims of this study were to verify the utilization of magnetic susceptibility measurements for the determination of contamination by potentially toxic elements (PTEs of urban soils in kindergartens in the capital city of Slovakia, Bratislava, and to determine the concentrations of selected PTEs like As, Cd, Cu, Hg, Pb and Zn in the soils. The results showed that the urban soils were contaminated mainly by Pb, Zn, Hg, and Cu with the concentrations between 11–183 mg·kg-1, 33–551 mg·kg-1, 0.024–0.431 mg·kg-1, and 9–67 mg·kg-1, respectively. Generally, the highest concentrations of PTEs were found in the soils of kindergartens that are located very close to roads with heavy traffic and in the oldest part of the city (1st district, whereas the lowest levels of PTEs were in residential areas (4th and 5th district. Significant correlation existed between the magnetic susceptibility and the levels of PTEs in urban soils, and indicated that the measurement of magnetic susceptibility might be a useful tool for identification of trace metal contamination in urban soils of Bratislava.

Ondrej ?urža

2013-12-01

49

Frost on Mars  

Science.gov (United States)

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

50

Tints, Shades and Frost  

Science.gov (United States)

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

51

Frost-covered dunes  

Science.gov (United States)

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

52

Importance of winter climate and soil frost for dissolved organic carbon (DOC) in boreal forest soils and streams : - implications for a changing climate  

OpenAIRE

Dissolved organic carbon (DOC) is a defining feature of surface waters in a large part of the world and it influences a variety of physical, chemical and biological processes in aquatic ecosystems. Riparian soils exert a major control on stream water chemistry in many northern latitude regions and provide a local source of DOC to adjacent streams. As the winter climate in northern regions is predicted to be particularly affected by climate change, it is important to investigate the sensitivit...

Haei, Mahsa

2011-01-01

53

Magnetic susceptibility and Heavy metals distribution from risk-cultivated soil around the iron-steel plant, China  

International Nuclear Information System (INIS)

Magnetic susceptibility is a non-conventional way that can be used for evaluating proxy soil heavy metals pollution. The paper monitors available heavy metals (Cu, Fe, Zn, and Mn) present in cultivated soils around iron-steel plant by soil magnetic susceptibility. Our study was located in an area with high pollution with small grid density of 250 m in China. Results showed that low field magnetic susceptibility was significantly correlated with available Cu, Zn, and Mn. No clear association exists between magnetic susceptibility and available Fe, soil organic matter, pH. Frequency dependent susceptibility >5% suggests the possible presence of super-paramagnetic particles, fly ashes produced during coal combustion. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

54

Frost in Charitum Montes  

Science.gov (United States)

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

55

Mineralogy, size, morphology and porosity of aggregates and their relationship with soil susceptibility to water erosion  

International Nuclear Information System (INIS)

Soil erosion has been considered as the main process related to losses of soil mass and decrease of productivity in cultivated lands as well as on e of the most important processes in landscape evolution. Attention has been paid to many pedological variables affecting intensity of erosion, but little to the influence of iron compounds on the type, size, shape and porosity of soil aggregates. In the present study, three lithopedodomains which were assumed to be closely related to the dominant lithology of the soil parent material, varying in the degree of water erosion intensity, were selected for further analysis which focused mainly on the influence of iron oxide mineralogy on the soil aggregation. Powder X-ray diffractometry, 80 K Moessbauer data and SEM images are used to correlate all these variables with observed erosion activity in the field. The present data indicate that the more the soil is rich in iron (hematite and/or goethite) or aluminium (gibbsite) (hydr)oxide, the smaller are its aggregates and is porous. Soils derived from metabasic rocks are much more susceptible to collapse under wetting than those from other lithologies. They have the highest iron and clay content. Schist-derived soil is richer in muscovite, has bigger aggregates and porous and are less prone to collapse, while the granite-derived soil presents relatively intermediate resistance, when humid

56

GIS-based soil liquefaction susceptibility map of Mumbai city for earthquake events  

Science.gov (United States)

The problem of liquefaction of soil during seismic event is one of the important topics in the field of Geotechnical Earthquake Engineering. Liquefaction of soil is generally occurs in loose cohesionless saturated soil when pore water pressure increases suddenly due to induced ground motion and shear strength of soil decreases to zero and leading the structure situated above to undergo a large settlement, or failure. The failures took place due to liquefaction induced soil movement spread over few square km area continuously. Hence this is a problem where spatial variation involves and to represent this spatial variation Geographic Information System (GIS) is very useful in decision making about the area subjected to liquefaction. In this paper, GIS software GRAM++ is used to prepare soil liquefaction susceptibility map for entire Mumbai city in India by marking three zones viz. critically liquefiable soil, moderately liquefiable soil and non liquefiable soil. Extensive field borehole test data for groundwater depth, standard penetration test (SPT) blow counts, dry density, wet density and specific gravity, etc. have been collected from different parts of Mumbai. Simplified procedure of Youd et al. (2001) is used for calculation of factor of safety against soil liquefaction potential. Mumbai city and suburban area are formed by reclaiming lands around seven islands since 1865 till current date and still it is progressing in the area such as Navi Mumbai and beyond Borivali to Mira road suburban area. The factors of safety against soil liquefaction were determined for earthquake moment magnitude ranging from Mw = 5.0 to 7.5. It is found that the areas like Borivali, Malad, Dahisar, Bhandup may prone to liquefaction for earthquake moment magnitude ranging from Mw = 5.0 to 7.5. The liquefaction susceptibility maps were created by using GRAM++ by showing the areas where the factor of safety against the soil liquefaction is less than one. Proposed liquefaction susceptibility map of Mumbai city can be used by researchers for earthquake hazard analysis, for the preventive measures in disaster management, for urban planning and further development of Mumbai city and suburban area.

Mhaske, Sumedh Yamaji; Choudhury, Deepankar

2010-03-01

57

Water frost on Charon  

Science.gov (United States)

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

58

Frost on Dunes  

Science.gov (United States)

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

59

Frost Forecasting for Fruitgrowers  

Science.gov (United States)

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

60

Magnetic susceptibility and the spatial variability of heavy metals in soils developed on basalt  

Science.gov (United States)

Topsoil magnetic susceptibility (?) is a fast and convenient method used to detect potentially polluted areas by heavy metals. Topsoil measurements are carried out in situ with Bartington MS2D loop sensor, designed to measure the magnetic susceptibility of top 10 cm of soil and detect 90% of the total signal from a depth of 6 cm. However, soils developed on basalt are difficult to assess due to their large amounts of ferrimagnetic minerals. The aim of this study was evaluate the applicability of ? to discriminate anthropogenic/lithogenic environments characterized by different parent materials in the city of Maringá/Brazil. In this paper, topsoil susceptibility (?) was measured in 66 urban soils using a Bartington MS2D loop sensor. To investigate the magnetic background levels, samples of a Rhodic Ferralsol profile were measured using a laboratory MS2B sensor. X-ray diffractometry (XRD) analysis was carried out to verify the mineralogical composition of the different lithology. Cu, Fe, Ni, Mn, Pb and Zn concentrations were measured in 29 topsoil samples. The ? values ranged from 316 × 10- 5 SI in a sandstone region to 6,945 × 10- 5 SI in soils developed on basalt. The ?fd values of urban topsoil varied from 2% to 11.3%. Lower values of ? and ?fd in the sandstone region indicated that the lithogenic contribution is of primary significance. Significant positive correlations between ? and Cu, Fe and Mn are related to the parent material, enriched in iron oxides, as verified by XRD. The background values (mean of 4,235 × 10- 8 m3 kg- 1) were higher in subsoil, suggesting the inexistence of anthropogenic pollution. The topsoil susceptibility was efficient for distinguish different lithogenic environments. Although anthropogenic pollution in soils developed on basalt is difficult to assess due to the high natural background, our results suggest that heavy metal contents are not related to the human activity.

Cervi, Eduardo Cimino; da Costa, Antonio Carlos Saraiva; de Souza Junior, Ivan Granemann

2014-12-01

61

Soil characterization using patterns of magnetic susceptibility versus effective radium concentration  

OpenAIRE

Low-field magnetic susceptibility ?m and effective radium concentration ECRa, obtained from radon emanation, have been measured in the laboratory with 129 soil samples from Nepal. Samples along horizontal profiles in slope debris or terrace scarps showed rather homogeneous values of both ?m and ECRa. One sample set, collected vertically on a lateritic terrace scarp, had homogeneous valu...

Girault, F.; Poitou, C.; Perrier, F.; Koirala, B. P.; Bhattarai, M.

2011-01-01

62

An investigation on magnetic susceptibility of hazardous saline-alkaline soils from the contaminated Hai River Basin, China.  

Science.gov (United States)

Magnetic susceptibility can provide rich environmental information, especially for hazardous heavy metals and saline-alkaline in the contaminated soils. Magnetic susceptibility in four vertical profiles from saline-alkaline soils in lower Hai River basin was investigated. Soil sites were extended from alluvial fan to coastal plain areas. They are aligned along a latitudinal strip. Magnetic parameters including low/high frequency susceptibility, frequency-dependent susceptibility was measured. Moreover, some standard pedological parameters such as pH value and organic matter content were also determined. The results showed that low frequency magnetic susceptibility values is very high at the surface and decreases with the profile to a low value. In all profiles from alluvial fan frequency-dependent susceptibility greater than 3% may suggest the presence of relatively more super-paramagnetic particles. Magnetic susceptibility showed obvious vertical distribution in alluvial fan higher than coastal plain. No significant correlations between organic matter, pH and low frequency magnetic susceptibility were found, while there is a negative correlation between organic matter and frequency-dependent susceptibility. A positive correlation between pH and frequency-dependent susceptibility was found in the study areas. PMID:19643536

Yang, Pingguo; Mao, Renzhao; Shao, Hongbo

2009-12-15

63

Sand Dunes with Frost  

Science.gov (United States)

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

64

Winter Frost and Fog  

Science.gov (United States)

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

65

ISOLATION AND ANTIBIOTIC SUSCEPTIBILITY TESTING OF RAPIDLY-GROWING MYCOBACTERIA FROM GRASSLAND SOILS  

Directory of Open Access Journals (Sweden)

Full Text Available Rapidly growing mycobacteria (RGM are common soil saprophytes, but certain strains cause infections in human and animals. The infections due to RGM have been increasing in past decades and are often difficult to treat. The susceptibility to antibiotics is regularly evaluated in clinical isolates of RGM, but the data on soil RGM are missing. The objectives of this study was to isolate RGM from four grassland soils with different impact of manuring, and assess their resistance to antibiotics and the ability to grow at 37°C and 42°C. Since isolation of RGM from soil is a challenge, a conventional decontamination method (NaOH/malachite green/cycloheximide and a recent method based on olive oil/SDS demulsification were compared. The olive oil/SDS method was less efficient, mainly because of the emulsion instability and plate overgrowing with other bacteria. Altogether, 44 isolates were obtained and 23 representatives of different RGM genotypes were screened. The number of isolates per soil decreased with increasing soil pH, consistently with previous findings that mycobacteria were more abundant in low pH soils. Most of the isolates belonged to the Mycobacterium fortuitum group. The majority of isolates was resistant to 2-4 antibiotics. Multiresistant strains occurred also in a control soil that has a long history without the exposure to antibiotic-containing manure. Seven isolates grew at 37°C, including the species M. septicum and M. fortuitum known for infections in humans. This study shows that multiresistant RGM close to known human pathogens occur in grassland soils regardless the soil history of manuring.

Martina Kyselková

2013-08-01

66

Continental level landslide susceptibility assessment in the context of the European Union's Soil Thematic Strategy  

Science.gov (United States)

In the context of the European Union's Soil Thematic Strategy, and the formulation of a draft of a European framework directive devoted to the sustainable protection of soil, landslides are recognized as one of the eight soil threats requiring harmonized spatial hazard assessments over the EU territory. The general framework for the harmonized assessment of soil threats (namely erosion, organic matter decline, salinisation, compaction, landslides, contamination, sealing and loss of biodiversity) consists of a nested geographical approach based on "Tiers", where a semi-quantitative, low-resolution (1:1 million) evaluation ("Tier 1") using already available pan-European datasets should enable the delineation of priority areas requiring more detailed quantitative inventory-based assessments with additional data ("Tier 2"). In this contribution, we present the elaboration of a continental level "Tier 1" generic landslide susceptibility model based on a heuristic, spatial multi-criteria evaluation (SMCE) approach exploiting the most important conditioning factors for landslides being slope gradient, lithology and land cover. Additionally, extensive landslide locations available at regional and national levels were collected, harmonized and standardized over the EU territory to obtain a signal for input parameter specification and model calibration, evaluation and classification. Since the analyzed area is highly complex in terms of climatic, physiographic and seismotectonic conditions controlling landslide occurrences, a terrain differentiation based on climatic and geomorphologic criteria is proposed to delineate distinct zones to which specific predictor class weights have been allocated through the SMCE approach for susceptibility evaluation. The heuristic indexing scheme is cross-validated with multivariate statistical evaluations in representative areas for which detailed inventory information is available. The resulting pan-European susceptibility estimate classifies 13% of the EU territory as generally prone to landslides, thus requiring more detailed, quantitative inventory-based susceptibility evaluations ("Tier 2"). Compared to globally parameterized susceptibility models, the terrain-differentiated assessment is able to spatially predict landslide occurrences more accurately at the continental scale. Future work will focus on the preparation of typologically differentiated continental-level landslide susceptibility models and maps over Europe.

Günther, A.; Van Den Eeckhaut, M.; Reichenbach, P.; Hervás, J.; Malet, J.; Guzzetti, F.

2011-12-01

67

Heavy Metals in Urban Soils of Xuzhou, China: Spatial Distribution and Correlation to Specific Magnetic Susceptibility  

Directory of Open Access Journals (Sweden)

Full Text Available The investigation of the anthropogenic contamination by heavy metals of soils is very important for environmental planning and monitoring in urban areas. In the present study, surface soils (0-20 cm samples from 167 sampling sites in Xuzhou (China were collected in 2010 and analyzed for heavy metals including Zn, Pb, Fe, Mn, Cu, Cd, Sr, Ba Cr, Ni and Mo via inductively coupled plasma/mass spectrometry (ICP-MS. Compared with their levels in natural soils of China, these metals investigated exhibited a slight build-up in Xuzhou topsoils. The multivariate statistical analyses including factor analysis (FA and cluster analysis (CA were performed. The obtained results enabled the identification of two main groups of metals, discriminating Ni, Mo and Cr from Zn, Pb, Fe, Mn, Cu, Cd, Sr and Ba. Signifcant associations between Pb, Zn, Fe and specific magnetic susceptibility (c indicated that specific susceptibility can serve as proxies for these metals levels in Xuzhou urban soils.

Xuesong Wang

2013-03-01

68

Frost-free Dunes  

Science.gov (United States)

[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

69

Frost on Mars Rover Opportunity  

Science.gov (United States)

Frost can form on surfaces if enough water is present and the temperature is sufficiently low. On each of NASA's Mars Exploration Rovers, the calibration target for the panoramic camera provides a good place to look for such events. A thin frost was observed by Opportunity's panoramic camera on the rover's 257th sol (Oct. 13, 2004) 11 minutes after sunrise (left image). The presence of the frost is most clearly seen on the post in the center of the target, particularly when compared with the unsegmented outer ring of the target, which is white. The post is normally black. For comparison, note the difference in appearance in the image on the right, taken about three hours later, after the frost had dissipated. Frost has not been observed at Spirit, where the amount of atmospheric water vapor is observed to be appreciably lower. Both images were taken through a filter centered at a wavelength of 440 nanometers (blue).

2004-01-01

70

Dunes with Frost  

Science.gov (United States)

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

71

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

Science.gov (United States)

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

72

Morphometry and land cover based multi-criteria analysis for assessing the soil erosion susceptibility of the western Himalayan watershed.  

Science.gov (United States)

Complex mountainous environments such as Himalayas are highly susceptibility to natural hazards particular those that are triggered by the action of water such as floods, soil erosion, mass movements and siltation of the hydro-electric power dams. Among all the natural hazards, soil erosion is the most implicit and the devastating hazard affecting the life and property of the millions of people living in these regions. Hence to review and devise strategies to reduce the adverse impacts of soil erosion is of utmost importance to the planners of watershed management programs in these regions. This paper demonstrates the use of satellite based remote sensing data coupled with the observational field data in a multi-criteria analytical (MCA) framework to estimate the soil erosion susceptibility of the sub-watersheds of the Rembiara basin falling in the western Himalaya, using geographical information system (GIS). In this paper, watershed morphometry and land cover are used as an inputs to the MCA framework to prioritize the sub-watersheds of this basin on the basis of their different susceptibilities to soil erosion. Methodology included the derivation of a set of drainage and land cover parameters that act as the indicators of erosion susceptibility. Further the output from the MCA resulted in the categorization of the sub-watersheds into low, medium, high and very high erosion susceptibility classes. A detailed prioritization map for the susceptible sub-watersheds based on the combined role of land cover and morphometry is finally presented. Besides, maps identifying the susceptible sub-watersheds based on morphometry and land cover only are also presented. The results of this study are part of the watershed management program in the study area and are directed to instigate appropriate measures to alleviate the soil erosion in the study area. PMID:25154685

Altaf, Sadaff; Meraj, Gowhar; Romshoo, Shakil Ahmad

2014-12-01

73

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

Science.gov (United States)

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

74

Managing potato biodiversity to cope with frost risk in the high Andes: a modeling perspective.  

Science.gov (United States)

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

75

Soil and water pollution studies from a waste site deposit in Bantama, Kumasi, Ghana using magnetic susceptibility measurements  

International Nuclear Information System (INIS)

The magnetic susceptibility of soil and water samples from around the Uadara barracks waste site deposit in Bantama, a suburb of Kumasi was measured with the aim of investigating the potential threat of pollution to the soil, streams, fish ponds and other water sources at the site around Armed Forces Senior High School campus which shares the same premises with the barracks. The studied soil samples were picked from the near surface (?10 cm depth) along profiles taken from the waste site towards the stream and the ponds. Again, water samples were picked along the stream and from ten (10) ponds aligned along the stream. Laboratory measurements of the magnetic susceptibility were done using the Bartington MS2 metre and the MS2B dual frequency sensor for the soil samples, and the MS2G sensor for the water samples. The soil samples from the site registered an average magnetic susceptibility of 180. 04 x 10-5 SI whereas the water samples recorded an average of -2.3 x 10-6 SI showing a significant increment in comparison with the standard water magnetic susceptibility of -9.04 x 10-6 SI. Thus, not withstand the lithology of the area studied, the presence of heavy metals and other chemical waste materials form the Uadara barracks garbage deposit site were found to greatly pollute the soil and particularly the water bodies around the Armed Forces Senior High School. (au)

76

Mapping soil erosion susceptibility using remote sensing and GIS: a case of the Upper Nam Wa Watershed, Nan Province, Thailand  

Science.gov (United States)

Land degradation is still a very common problem in the mountains of Asia because of inappropriate land use practice in steep topography. Many studies have been carried out to map shifting cultivation and areas susceptible to soil erosion. Mostly, estimated soil loss is taken as the basis to classify the level of soil loss susceptibility of area. Factors that influence soil erosion are: rainfall erosivity, soil erodibility, slope length and steepness, crop management and conservation practices. Thus the reliability of estimated soil loss is based on how accurately the different factors were estimated or prepared. As each and every small pixel of our earth surface is different from one area to another, the manner in which the study area was discretized into smaller homogenous sizes and how the most accurate and efficient technique were adopted to estimate the soil loss are very important. The purpose of this study is to produce erosion susceptibility maps for an area that has suffered because of shifting cultivation located in the mountainous regions of Northern Thailand. For this purpose, an integrated approach using RS and GIS-based methods is proposed. Data from the Upper Nam Wa Watershed, a mountainous area of the Northern Thailand were used. An Earth Resources Data Analysis System (ERDAS) imagine image processor has been used for the digital analysis of satellite data and topographical analysis of the contour data for deriving the land use/land cover and the topographical data of the watershed, respectively. ARCInfo and ARCView have been used for carrying out geographical data analysis. The watershed was discretized into hydrologically, topographically, and geographically homogeneous grid cells to capture the watershed heterogeneity. The soil erosion in each cell was calculated using the universal soil loss equation (USLE) by carefully determining its various parameters and classifying the watershed into different levels of soil erosion severity. Results show that during the time of this study most of the areas under shifting cultivation fell in the highest severity class of susceptibility.

Krishna Bahadur, K. C.

2009-04-01

77

Soil characterization using patterns of magnetic susceptibility versus effective radium concentration  

Directory of Open Access Journals (Sweden)

Full Text Available Low-field magnetic susceptibility ?m and effective radium concentration ECRa, obtained from radon emanation, have been measured in the laboratory with 129 soil samples from Nepal. Samples along horizontal profiles in slope debris or terrace scarps showed rather homogeneous values of both ?m and ECRa. One sample set, collected vertically on a lateritic terrace scarp, had homogeneous values of ECRa while ?m increased by a factor of 1 to 10 for residual soils and topsoils. However, for a set of samples collected on three imbricated river terraces, values of ECRa, homogeneous over a given terrace, displayed a gradual increase from younger to older terraces. By contrast, ?m showed more homogeneous mean values over the three terraces, with a larger dispersion, however, for the younger one. Similarly, Kathmandu sediments exhibited a large increase in ECRa from sand to clay layers, while ?m increased moderately. The combination of ?m and ECRa, thus, provides a novel tool to characterize quantitatively various soil groups and may be of interest to distinguish modes of alteration or deposition histories.

F. Girault

2011-08-01

78

Quantitative assessment of the piping erosion susceptibility of loess-derived soil horizons using the pinhole test  

Science.gov (United States)

The pinhole test is an empirical test based on the qualitative evaluation of the dispersivity (colloidal erodibility) of compacted fined-grained soils. This paper evaluates the pinhole test device for the quantitative assessment of the susceptibility of soil horizons to piping, assesses the effects of hydraulic head, water quality, antecedent soil moisture content and soil disturbance on the hydrological and erosion response during pipeflow, and formulates recommendations for the application of the pinhole test to study piping erosion processes. In total, 255 pinhole test experiments were conducted. The results obtained from disturbed soil samples (A p horizon) indicate: (i) a significant positive linear increase in pipeflow discharge ( Qw) and sediment discharge ( Qs) with increasing hydraulic head, (ii) no relationship between Qw and antecedent soil moisture content ( ASM), but significant and negative relationship between Qs and ASM, and (iii) significantly higher Qs for distilled water than for tap water. The use of disturbed soil samples resulted in significantly more rapid flow responses and lower sediment discharges than for undisturbed soil samples. The pinhole test experiments performed on different loess-derived soil horizons show that the plowed topsoil (A p) and the underlying clay-enriched horizon (B t) are at least two times less susceptible to piping than the decalcified (C 1) and the calcareous horizons (C 2). This confirms field observations indicating that loess-derived soil horizons are very susceptible for piping erosion, especially when the C horizon crops out. This study demonstrates that the pinhole test is suitable for assessing the susceptibility of soil horizons to piping in a quantitative way (i.e. Qw, Qs, the time to outflow and the cross-section of the pipe after the test). We recommend the use of: (i) two different hydraulic heads (i.e. 180 and 1020 mm), (ii) distilled water, (iii) contrasting antecedent soil moisture contents of the soil samples to be tested, and (iv) different soil sampling methods to investigate the effect of soil disturbance, and particularly to obtain a better understanding of the sediment response during pipeflow.

Nadal-Romero, E.; Verachtert, E.; Maes, R.; Poesen, J.

2011-12-01

79

An Artistic Analysis on Robert Frost’s Desert Places  

OpenAIRE

Desert Places is one of Frost’s dark poems that show the poet’s deep thought about life philosophy and helplessness towards reality. This article analyzes this dark poem from the perspective of elements to show that how these elements work together to reinforce the theme of the poem in order to help readers to have a better understanding about this poem as well as the artistic techniques the author employed to elaborate the life wisdom through image and common settings. The elemen...

Li Wang

2013-01-01

80

An Artistic Analysis on Robert Frost’s Desert Places  

Directory of Open Access Journals (Sweden)

Full Text Available Desert Places is one of Frost’s dark poems that show the poet’s deep thought about life philosophy and helplessness towards reality. This article analyzes this dark poem from the perspective of elements to show that how these elements work together to reinforce the theme of the poem in order to help readers to have a better understanding about this poem as well as the artistic techniques the author employed to elaborate the life wisdom through image and common settings. The elements include title, setting, imagery, syntax, sound quality, rhyme scheme, rhythm, figures of speech, diction and tone. 

Li Wang

2013-11-01

81

Neural Network-Based Model for Landslide Susceptibility and Soil Longitudinal Profile Analyses : two case studies  

DEFF Research Database (Denmark)

The purpose of this study was to create an empirical model for assessing the landslide risk potential at Savadkouh Azad University, which is located in the rural surroundings of Savadkouh, about 5 km from the city of Pol-Sefid in northern Iran. The soil longitudinal profile of the city of Babol, located 25 km from the Caspian Sea, also was predicted with an artificial neural network (ANN). A multilayer perceptron neural network model was applied to the landslide area and was used to analyze specific elements in the study area that contributed to previous landsliding events. The ANN models were trained with geotechnical data obtained from an investigation of the study area. The quality of the modeling was improved further by the application of some controlling techniques involved in ANN. The observed >90% overall accuracy produced by the ANN technique in both cases is promising for future studies in landslide susceptibility zonation.

Farrokhzad, F.; Barari, Amin

2011-01-01

82

Evaluation of Cover Crops with Potential for Use in Anaerobic Soil Disinfestation (ASD) for Susceptibility to Three Species of Meloidogyne  

Science.gov (United States)

Several cover crops with potential for use in tropical and subtropical regions were assessed for susceptibility to three common species of root-knot nematode, Meloidogyne arenaria, M. incognita, and M. javanica. Crops were selected based on potential use as organic amendments in anaerobic soil disin...

83

Tolerância de frutos de pessegueiro a geadas / Fruit frost tolerance in peach  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Este trabalho teve como objetivo avaliar a tolerância de frutos de pessegueiro aos danos ocasionados pela geada. A geada ocorreu no dia 5 de setembro de 2006, sendo que a temperatura mínima, a 1,5 m do solo, foi de - 1,06ºC. Foram avaliados 28 genótipos de pessegueiro em diferentes estádios fenológi [...] cos. O delineamento experimental foi o inteiramente casualizado, com três repetições (plantas de pessegueiro), procedendo-se à avaliação em seis ramos por planta. No dia em que ocorreu a geada, foram mensurados o número de frutos por ramo, diâmetro sutural médio dos frutos, número total de gemas vegetativas, percentual de brotação e percentual de brindilas formadas a partir das gemas brotadas. Uma segunda avaliação foi realizada 15 dias após a primeira, para avaliar o percentual de queda de frutos e o diâmetro sutural médio dos frutos remanescentes. Genótipos bem enfolhados e cujos frutos apresentavam endocarpo endurecido, no momento da ocorrência da geada, foram tolerantes ao dano ocasionado pelo frio; frutos com diâmetro sutural inferior a 20 mm foram suscetíveis à geada, enquanto frutos com diâmetro sutural superior a 30 mm apresentaram boa tolerância, independentemente do genótipo avaliado. Abstract in english The aim of this work was to evaluate the fruit damage tolerance in different peach tree genotypes after natural freeze. The frost happened on September 5, 2006, and the minimum temperature, 1.5 meters over soil, was -1.06ºC. Twenty- eight peach tree genotypes, in different stages of development, wer [...] e evaluated, in a completely random design, in three replication (plants) and six branches by plants. Immediately after frost, we measured the number of fruits per branches, average fruit suture diameter, percentage of sprouts and percentage of twigs in formation. A second evaluation was accomplished fifteen days after the first one in order to assess the percentage of fruit drop and the average remaining fruit suture diameter. Genotypes with good leafing and hard pit (endocarp) during frost have freeze tolerance; fruits with suture diameter lass than 20 mm are susceptible to frost damage, while fruits with suture diameter superior to 30 mm are tolerant.

André Paulo, Assmann; Idemir, Citadin; Mauro Cristovão, Locatelli; Silvia, Scariot; Moeses Andrigo, Danner; Maria do Carmo Bassols, Raseira.

1030-10-01

84

Tolerância de frutos de pessegueiro a geadas Fruit frost tolerance in peach  

Directory of Open Access Journals (Sweden)

Full Text Available Este trabalho teve como objetivo avaliar a tolerância de frutos de pessegueiro aos danos ocasionados pela geada. A geada ocorreu no dia 5 de setembro de 2006, sendo que a temperatura mínima, a 1,5 m do solo, foi de - 1,06ºC. Foram avaliados 28 genótipos de pessegueiro em diferentes estádios fenológicos. O delineamento experimental foi o inteiramente casualizado, com três repetições (plantas de pessegueiro, procedendo-se à avaliação em seis ramos por planta. No dia em que ocorreu a geada, foram mensurados o número de frutos por ramo, diâmetro sutural médio dos frutos, número total de gemas vegetativas, percentual de brotação e percentual de brindilas formadas a partir das gemas brotadas. Uma segunda avaliação foi realizada 15 dias após a primeira, para avaliar o percentual de queda de frutos e o diâmetro sutural médio dos frutos remanescentes. Genótipos bem enfolhados e cujos frutos apresentavam endocarpo endurecido, no momento da ocorrência da geada, foram tolerantes ao dano ocasionado pelo frio; frutos com diâmetro sutural inferior a 20 mm foram suscetíveis à geada, enquanto frutos com diâmetro sutural superior a 30 mm apresentaram boa tolerância, independentemente do genótipo avaliado.The aim of this work was to evaluate the fruit damage tolerance in different peach tree genotypes after natural freeze. The frost happened on September 5, 2006, and the minimum temperature, 1.5 meters over soil, was -1.06ºC. Twenty- eight peach tree genotypes, in different stages of development, were evaluated, in a completely random design, in three replication (plants and six branches by plants. Immediately after frost, we measured the number of fruits per branches, average fruit suture diameter, percentage of sprouts and percentage of twigs in formation. A second evaluation was accomplished fifteen days after the first one in order to assess the percentage of fruit drop and the average remaining fruit suture diameter. Genotypes with good leafing and hard pit (endocarp during frost have freeze tolerance; fruits with suture diameter lass than 20 mm are susceptible to frost damage, while fruits with suture diameter superior to 30 mm are tolerant.

André Paulo Assmann

2008-12-01

85

Cave development by frost weathering  

Science.gov (United States)

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

86

Suscetibilidade de dois tipos de solo à compactação Compaction susceptibility of two classes of soil  

Directory of Open Access Journals (Sweden)

Full Text Available Com vistas ao aumento da produção agrícola, optou-se no Brasil, pelo acréscimo de área cultivada; para tal o uso indiscriminado da motomecanização mostrou-se eficiente em um primeiro momento, porém acarretando problemas à física do solo no decorrer dos anos. Paralelamente, práticas conservacionistas se fazem presentes, vide semeadura sob a palha (Plantio Direto, uma realidade no sul do Brasil. Sendo assim, avaliou-se a suscetibilidade de compactação de dois tipos de solo, ambos com sistema de semeadura sob a palha. Para dimensionar a suscetibilidade a compactação, utilizou-se ensaio de Proctor. Os solos foram ensaiados com e sem a presença de matéria orgânica livre. Os resultados demonstraram que para o Cambissolo, textura média, não houve diferença nos valores que representam a suscetibilidade, enquanto no Latossolo Vermelho, textura argilosa, não houve diferença entre a máxima densidade aparente, porém houve diferença significativa no conteúdo de água para a máxima densidade, o mesmo alterou-se de 0,249 g g-1 no ponto de máxima compactação no ensaio sem a presença de matéria orgânica livre, para 0,283 g g-1 no ponto de máxima compactação, quando da presença da matéria orgânica livre.For increasing agricultural production, Brazil opted to enlarge the cultivated area, and indiscriminate mechanization was efficient at the first moment, although it altered adversely the soil properties with the passage of time. At the same time, conservation practices, like the direct sowing under the straw (No Tillage were adopted which is a reality in Southern Brazil. Considering this, the susceptibility for compaction of two classes of soil was evaluated under no tillage system, with and without free organic matter. The Proctor test was used to measure the degree of compaction. The results of a medium texture Cambissol showed there was no difference in susceptibility for compaction. The clay textured Red Latossol, showed no difference in the maximum apparent density, although there was significant difference in water content at maximum density. The values altered from 0.249 g g-1, at a maximum compaction point without free organic matter to 0.283 g g-1 with free organic matter.

Pedro H. Weirich Neto

2002-01-01

87

Suscetibilidade de dois tipos de solo à compactação / Compaction susceptibility of two classes of soil  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Com vistas ao aumento da produção agrícola, optou-se no Brasil, pelo acréscimo de área cultivada; para tal o uso indiscriminado da motomecanização mostrou-se eficiente em um primeiro momento, porém acarretando problemas à física do solo no decorrer dos anos. Paralelamente, práticas conservacionistas [...] se fazem presentes, vide semeadura sob a palha (Plantio Direto), uma realidade no sul do Brasil. Sendo assim, avaliou-se a suscetibilidade de compactação de dois tipos de solo, ambos com sistema de semeadura sob a palha. Para dimensionar a suscetibilidade a compactação, utilizou-se ensaio de Proctor. Os solos foram ensaiados com e sem a presença de matéria orgânica livre. Os resultados demonstraram que para o Cambissolo, textura média, não houve diferença nos valores que representam a suscetibilidade, enquanto no Latossolo Vermelho, textura argilosa, não houve diferença entre a máxima densidade aparente, porém houve diferença significativa no conteúdo de água para a máxima densidade, o mesmo alterou-se de 0,249 g g-1 no ponto de máxima compactação no ensaio sem a presença de matéria orgânica livre, para 0,283 g g-1 no ponto de máxima compactação, quando da presença da matéria orgânica livre. Abstract in english For increasing agricultural production, Brazil opted to enlarge the cultivated area, and indiscriminate mechanization was efficient at the first moment, although it altered adversely the soil properties with the passage of time. At the same time, conservation practices, like the direct sowing under [...] the straw (No Tillage) were adopted which is a reality in Southern Brazil. Considering this, the susceptibility for compaction of two classes of soil was evaluated under no tillage system, with and without free organic matter. The Proctor test was used to measure the degree of compaction. The results of a medium texture Cambissol showed there was no difference in susceptibility for compaction. The clay textured Red Latossol, showed no difference in the maximum apparent density, although there was significant difference in water content at maximum density. The values altered from 0.249 g g-1, at a maximum compaction point without free organic matter to 0.283 g g-1 with free organic matter.

Pedro H., Weirich Neto; André L. T. da, Rosa; Jaime A., Gomes.

88

Frost heave modelling of buried pipelines using non-linear Fourier finite elements  

International Nuclear Information System (INIS)

Numerical analysis of the response of a three-dimensional soil-pipeline system in a freezing environment using non-linear Fourier finite elements was described as an illustration of the effectiveness of this technique in analyzing plasticity problems. Plastic deformations occur when buried pipeline is under the action of non-uniform frost heave. The three-dimensional frost heave which develops over time including elastoplastic deformations of the soil and pipe are computed. The soil heave profile obtained in the numerical analysis was consistent with experimental findings for similar configurations. 8 refs., 8 figs

89

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

Science.gov (United States)

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

90

Mapping Statistical Characteristics of Frosts in Iran  

Science.gov (United States)

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

91

Meteorological and micrometeorological applications to frost monitoring in northern Italy orchards  

Science.gov (United States)

Late frost are dangerous climatic hazards that can be responsible of fruit trees yield losses. Late frost potential hazard is, in particular, increased by the enhancement of low-temperature episodes in spring and to the concomitant early-blooming consequent to higher winter temperatures induced by the earth global warming. This paper reports observations on the micrometeorological features associated to frost occurrence in a representative area of the Po valley in order to characterize the atmospheric physics during frost formation episodes, to understand the frequency and the type of risk and to develop the most suitable protection practices. Energy balance and soil radiation balance are reported together with the main atmospheric features (air turbulence included), and the data-set collected are verified against the similarity equations. The computation of the surface roughness and the friction velocity, fundamental to the definition of the distinctive features of the site, has been also done by applying the similarity theory.

Rossi, Federica; Facini, Osvaldo; Loreti, Silvia; Nardino, Marianna; Georgiadis, Teodoro; Zinoni, Franco

92

Frost resistance in alpine woody plants  

OpenAIRE

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 sm...

Neuner, Gilbert

2014-01-01

93

Frost risks in the Mantaro river basin  

OpenAIRE

As part of the study on the Mantaro river basin's (central Andes of Perú) current vulnerability to climate change, the temporal and spatial characteristics of frosts were analysed. These characteristics included intensity, frequency, duration, frost-free periods, area distribution and historical trends. Maps of frost risk were determined for the entire river basin, by means of mathematical algorithms and GIS (Geographic Information Systems) tools, using minimum temperature – 1...

Trasmonte, G.; Chavez, R.; Segura, B.; Rosales, J. L.

2008-01-01

94

Frost resistance in alpine woody plants.  

Science.gov (United States)

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

95

Unilateral frosted branch angiitis with vitreous haemorrhage.  

Directory of Open Access Journals (Sweden)

Full Text Available Idiopathic retinal frosted branch angiitis is a rare bilateral condition and presents with an acute reduction of vision. Unilateral affection is rare. We report an unusual case of unilateral frosted branch angiitis where the patient developed total vitreous haemorrhage.

Agrawal S

2001-01-01

96

FROST CONTROL IN THE PACIFIC NORTHWEST  

Science.gov (United States)

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...

97

Morning Frost on Martian Surface  

Science.gov (United States)

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

98

Restoring sedges and mosses into frost heaving iron fens, San Juan Mountains, Colorado  

Directory of Open Access Journals (Sweden)

Full Text Available Rare iron fens in the San Juan Mountains of Colorado are frequently in poor condition due to mining, roads and ditches, which have left much of the fen completely bare of vegetation. Natural revegetation is slow to occur in the bare areas because of severe frost heave in the cold mountain climate. Therefore, experimental revegetation plots were conducted in a factorial design with mulching and no mulching, crossed with moss diaspores, sedge transplants, and moss and sedge combined. Mulching influenced surface soil temperatures by reducing the midday highs and increasing the night-time lows, which decreased the frequency and amount of frost heave. Peat moisture also modified frost heave, with the greatest frost heaving occurring near 75 % peat moisture content (water table 10–20 cm below the surface and the least when soils were either wetter or drier. Moss survival was dependent on mulch, with no moss surviving in plots without mulch. Mulching also increased sedge transplant survival. In summary, mulching significantly increased the success of vegetation restoration efforts for frost heave areas in mountain fens.

R.A. Chimner

2011-08-01

99

Ground frost problems where district heating culverts cross under roads. Inventory of problems and theoretical analysis  

Energy Technology Data Exchange (ETDEWEB)

Heat losses from district heating culverts affect ground frost by thaw in surrounding soil leading to up to 20 cm high humps on roads where culverts cross until the time when the frost is breaking up. Even larger height differences were observed during the thaw period. Obviously several drawbacks for both road users and maintenance ensue. Effective insulation of culverts or removal of remaining heat leakage through insulated and ventilated conduits cause, however, new problems through frost penetrating under the culvert with resultant lifting and damage during the frost breaking phase. Another idea is to dissipate excess heat in the sub-soil by extended layers of polystyrene sheets to neutralize the differences of frost depth above and astride culverts. An investigation based on questionnaires sent to energy suppliers and appropiate communal authorities showed that the problems were serious enough to warrant a closer study and economical acceptabel solution. An analysis lead to a computer based differential calculation method taking regard to all relevant factors. When a practical method is found field trials or/ and laboratory tests are proposed.

Janson, L.E.

1984-01-01

100

AVALIAÇÃO DA SUSCEPTIBILIDADE DE SOLOS GNAISSICOS À EROSÃO SUBSUPERFICIAL / Evaluation of piping erosion susceptibility in gnaissic soils  

Directory of Open Access Journals (Sweden)

Full Text Available The basement rock areas of the Maracujá hydrographic basin show great incidence of hugegullies. This work aims to investigate the influence of the underground erosive processes inthe evolution of these features and to understand how the mineralogical and textural factorscould affect soil erodibility, specially of the saprolites, since the lateric soils of this basin aremore resistant to erosion. So, basic characterization and erodibility essays were carried out in representative soil samples. Soil susceptibility to piping and seepage erosion were investigatedthrough current and modified pin-hole-essays. Laboratory physical models were used in orderto observe these and other possible underground erosion mechanisms, especially the slides.However, piping erosion only occurs in the unsaturated portion of gully slopes, provoked bythe concentration of superficial water, since pipes are not stable under total saturation, whentheir roofs tend to collapse, because of the low cohesion of these saprolites. In the other hand,slumps are very common in the saturated portion of gullies, affecting saprolites even in smalland low declivity slopes.

Frederico Garcia Sobreira

2007-12-01

101

Future bloom and blossom frost risk for Malus domestica considering climate model and impact model uncertainties.  

Science.gov (United States)

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

102

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

Science.gov (United States)

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

103

Field and Dual Magnetic Susceptibility Proxies Implication for Heavy Metal Pollution Assessment in the Urban Soil of Al-Karak City, South Jordan.  

Science.gov (United States)

A total of 115 urban soil samples collected on grid bases from Al-Karak City, south Jordan, were investigated for their magnetic properties using Bartington portable magnetic susceptibility system with (MS2B and MS2D) probes. The magnetic proxies that were used in this study are the field & dual magnetic susceptibilities (?). In addition the heavy metal contents in soil were determined using the Inductively Coupled Plasma (ICP-MS). The dual frequency magnetic susceptibility meter (MS2B) measurements showed that upper soils have higher values of (?lf) than lower soils. Moreover, the large grain size particles have more magnetic materials than smaller grain size particles. This might be attributed to the lack or low degree of pedogensis due to prevailing arid climate. The field magnetic susceptibility measurements (?field) were positively correlated with low frequency dual magnetic susceptibility (?lf). Few selected samples that have anomalous magnetic susceptibility values were analyzed for their heavy metal content. The results showed a positively significant correlation between total heavy metal content and ?, this was evident from the higher degree of fitness between the distribution maps of ? and each heavy metal in the study area. These results indicate the applicability of these proxies as pollution indicator, and showed that higher ? is associated with traffic areas more than industrial and residential areas. The Frequency Dependent Susceptibility (?fd% ) was found to be medium value and ranges between (2-10%), which indicate the presence of admixture of fine Super magnetic Particles (SP) or coarse non-SP grains or SP grains heavy metal and magnetic parameters was additionally evidenced by using the index of pollution (IP) method, where the samples of high IP for (?lf) are almost the same samples that have high IP of THM content.

El-Hasan, T.; Lataifeh, M.

2012-04-01

104

Frost streaks in the south polar cap of Mars  

Science.gov (United States)

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

105

Frost Growth and Densification in Laminar Flow Over Flat Surfaces  

Science.gov (United States)

One-dimensional frost growth and densification in laminar flow over flat surfaces has been theoretically investigated. Improved representations of frost density and effective thermal conductivity applicable to a wide range of frost circumstances have been incorporated. The validity of the proposed model considering heat and mass diffusion in the frost layer is tested by a comparison of the predictions with data from various investigators for frost parameters including frost thickness, frost surface temperature, frost density and heat flux. The test conditions cover a range of wall temperature, air humidity ratio, air velocity, and air temperature, and the effect of these variables on the frost parameters has been exemplified. Satisfactory agreement is achieved between the model predictions and the various test data considered. The prevailing uncertainties concerning the role air velocity and air temperature on frost development have been elucidated. It is concluded that that for flat surfaces increases in air velocity have no appreciable effect on frost thickness but contribute to significant frost densification, while increase in air temperatures results in a slight increase the frost thickness and appreciable frost densification.

Kandula, Max

2011-01-01

106

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

OpenAIRE

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 de...

Hoffmann, Holger; Rath, Thomas

2013-01-01

107

Time as An Important Soil-Forming Factor Influencing Modern and Ancient Magnetic Susceptibility Enhancement Along the Delaware River Valley, USA  

Science.gov (United States)

Magnetic susceptibility is an increasingly popular low-cost method for rapidly assessing paleoclimate and paleoenvironmental impact on buried soils. The goal of this study is to determine the primary influence(s) on soil magnetic susceptibility along floodplain, terrace and upland soils in the middle Delaware River Valley, USA, using environmental magnetic, pedologic, and stratigraphic techniques. Two-hundred thirty samples were collected from age-constrained sandy, quartz-rich, floodplain, terrace, and upland soils (Entisols, Inceptisols). A Kruskal-Wallis (K-W) and post-hoc Tukey-Kramer (T-K) (?=0.05) multiple comparisons analysis on 176 mass-specific low-field susceptibility (Xlf) assays show that A and B horizons are magnetically enhanced compared to C and E horizons (p<0.0001). Results of descriptive soil micromorphology show that A and B horizons contain anywhere from 10-50% more amorphous organic matter and clay films along pores than do C and E horizons. Enhanced Xlf values also correlate positively (R^2=0.63) with the soil molecular weathering ratio of Alumina/Bases, suggesting that increased weathering likely results in the formation of pedogenic magnetic minerals and enhanced magnetic susceptibility signal. Additional K-W and T-K testing show that Xlf results, when grouped by floodplain-terrace designation (i.e., chronofunction) are significantly different (p<0.0001). The older T3 terrace and upland Xlf values (0.34±0.14 10^-6 m^3 kg^-1) are greater than the younger T2 terrace (0.18±0.06 10^-6 m^3 kg^-1) values, which are greater than modern floodplain (0.09±0.01 10^-6 m^3 kg^-1) Xlf values. These data suggest that longer intervals of soil formation enhance the ?lf value. This hypothesis is further supported when 159 Xlf values are plotted vs. age for the entire Holocene. A locally-weighted regression smoothing curve (LOESS) shows two distinct intervals of magnetic enhancement during previously established dry intervals, the early and late-middle Holocene. We hypothesize that prolonged drought during the early and middle Holocene reduced flood frequency and magnitude and the likelihood of soil burial, resulting in longer soil forming intervals and higher Xlf values. Although precipitation influences the Xlf signature, the results from this study suggest that the magnetic susceptibility values of well-drained buried floodplain soils along the Delaware River Valley are partly a function of time.

Stinchcomb, G. E.; Peppe, D. J.; Driese, S. G.

2011-12-01

108

Frost resistance of fibre reinforced concrete structures  

DEFF Research Database (Denmark)

Frost resistance of fibre reinforced concrete with 2.5-4.2% air and 6-9% air (% by volume in fresh concrete) casted in the laboratory and in-situ is compared. Steel fibres with hooked ends (ZP, length 30 mm) and polypropylene fibres (PP, CS, length 12 mm) are applied. It is shown that· addition of 0.4-1% by volume of fibres cannot replace air entrainment in order to secure a frost resistant concrete; the minimum amount of air needed to make the concrete frost resistant is not changed when adding fibres· the amount of air entrainment must be increased when fibres are added to establish the same amount of air pores as in the corresponding concrete without fibres

Hansen, Ernst Jan De Place

1999-01-01

109

Visualization of frosting phenomena by using neutron radiography  

International Nuclear Information System (INIS)

This study focuses on the frost formation on the fin-tube heat exchanger using neutron radiography. The visualization of the frost formation was estimated by the attenuation of the neutron beam through the water. The visualization image of the neutron radiography shows clearly the frost formation phenomena on the fin-tube heat exchanger. The rapid frost formation was observed at the fin and tube edges. Local mass transfer coefficient can be calculated from the differential images of the neutron radiography. (author)

110

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

Science.gov (United States)

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

111

Avaliação da susceptibilidade de solos gnaissicos à erosão subsuperficial / Evaluation of piping erosion susceptibility in gnaissic soils  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese As áreas com rochas do embasamento cristalino da bacia do rio Maracujá apresentam grande incidência de voçorocas de grandes dimensões. O presente trabalho objetivou investigar a influência dos processos erosivos subsuperficiais na evolução destas formas de erosão, além de compreender quais os fatore [...] s mineralógicos e texturais que poderiam influenciar na erodibilidade dos solos da bacia, especialmente dos saprolitos. Para tanto, foram realizados ensaios de caracterização básica e de avaliação da erodibilidade em amostras representativas, sendo o principal destes o ensaio de pin-hole, que avalia a suscetibilidade dos solos à erosão por piping e, com modificações, também por erosão por carreamento. Foram construídos em laboratório modelos físicos a fim de se observar estes e outros possíveis mecanismos de erosão atuantes nos taludes das voçorocas, especialmente os escorregamentos. Os resultados mostram que as voçorocas da bacia não sofrem influência significativa dos pipings em seu avanço, tendo em vista que estes só ocorrem na parte não saturada dos taludes das voçorocas, quando são formados pela ação da concentração de águas superficiais. Isto se dá porque os saprolitos colapsam quando saturados em função de sua baixa coesão, fazendo com que os pipings não se preservem. Por outro lado, as experiências com modelagem física e os dados de campo evidenciam que os saprolitos, quando saturados, instabilizam-se por meio de escorregamentos rotacionais (slumps), mesmo em taludes baixos e pouco íngremes. Abstract in english The basement rock areas of the Maracujá hydrographic basin show great incidence of huge gullies. This work aims to investigate the influence of the underground erosive processes in the evolution of these features and to understand how the mineralogical and textural factors could affect soil erodibil [...] ity, specially of the saprolites, since the lateric soils of this basin are more resistant to erosion. So, basic characterization and erodibility essays were carried out in representative soil samples. Soil susceptibility to piping and seepage erosion were investigated through current and modified pin-hole-essays. Laboratory physical models were used in order to observe these and other possible underground erosion mechanisms, especially the slides. However, piping erosion only occurs in the unsaturated portion of gully slopes, provoked by the concentration of superficial water, since pipes are not stable under total saturation, when their roofs tend to collapse, because of the low cohesion of these saprolites. In the other hand, slumps are very common in the saturated portion of gullies, affecting saprolites even in small and low declivity slopes.

Fernando, Morais; Luis Almeida Prado, Bacellar; Frederico Garcia, Sobreira.

2007-12-01

112

Nutritional Status and Susceptibility of Advanced Chickpea Germplasm to Low Soil Zinc and Boron  

Directory of Open Access Journals (Sweden)

Full Text Available Shoot samples at preflowering stage and grains at maturity from four replicated field trials on advanced germplasm of chickpea along with some of the commercial varieties were collected. Three trials consisted of Desi germplasm with 12, 12, and 8 entries while the fourth one had 11 entries of Kabuli material. The advanced lines appeared to be highly promising as they gave maximum increase over the old check varieties in grain yield upto 60 percent in first trial followed by 58 percent in second, 53 percent in third and 43 percent in the 4th one. On the overall basis, the whole germplasm under study contained sufficient B and Cu, while Zn and P (in grain were marginal if not deficient. Almost all the material had relatively higher B in the grain than that of cereals like wheat. After field survey, a followup soil pot culture study was conducted employing 5 varieties and 2 lines on a soil with marginal Zn and B. Variety 6153 responded to 5 mg kg -1 Zn application by 39, CM 72 by 26, NIFA 95 by 17 and mutant CM 1571-1-A by 11 percent, while remaining responded negligibly. Mutant CM 31-1 responded to 1 mg kg -1 B application by 30, CM 1571-1-A, C 44 and 6153 shared the response by 27 percent. Remaining three did not respond or responded negatively. All the entries in the four trials contained marginal Zn i.e.,<20 mg kg-1 and sufficient B i.e., >30 mg kg-1, yet some of them responded to the applications markedly indicating their high B and Zn requirement than reported in the literature.

M.A.Kausar

2000-01-01

113

Latest results from FROST at Jefferson Lab  

Energy Technology Data Exchange (ETDEWEB)

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

114

Insulator (Heat and Frost). Occupational Analyses Series.  

Science.gov (United States)

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

115

Fatores abióticos envolvidos na tolerância de trigo à geada / Abiotic factors involved in wheat tolerance to frost  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese O objetivo deste trabalho foi avaliar a influência da aclimatação, da intensidade de geada e da disponibilidade hídrica sobre os danos causados pela geada em trigo. Os experimentos foram conduzidos em telados, com trigo cultivado em vasos. A aclimatação e a incidência de geada foram simuladas em câm [...] aras de crescimento. Os fatores abióticos avaliados foram: regimes de aclimatação (com e sem); gradiente de temperatura (2, -2, -4 e -7°C); e variação de disponibilidade hídrica no solo, antes da geada (9, 6, 3 e 1 dia sem irrigação). Todos os fatores foram avaliados no afilhamento, alongamento e espigamento das cultivares: BR-18 Terena, mais tolerante à geada; e BRS 194, menos tolerante. As variáveis avaliadas foram: grau de queima de folhas, sete dias após a geada; massa de matéria seca total; e massa de grãos. A aclimatação do trigo, antes da geada, diminuiu os danos provocados antes do espigamento, e resultou em menor queima de folhas e maior rendimento de grãos. A temperatura de -7°C, no espigamento, resultou em falha na produção de grãos de ambas as cultivares; e os prejuízos com geada foram menores nas plantas com nove dias sem irrigação. As condições anteriores à ocorrência de geada têm influência sobre os danos provocados por ela. Abstract in english The objective of this work was to evaluate the influence of acclimatization, frost intensity and soil water availability on damage caused by frost on wheat. The experiments were carried out in screen house conditions. The wheat plants were grown in pots. The acclimatization and frost incidence were [...] simulated in a growth chamber. The abiotic factors evaluated were: acclimatization regimes (with and without); temperature gradient (2, -2, -4 and -7°C) and variation of soil water availability prior to frost incidence (9, 6, 3 and 1 day without irrigation). All factors were evaluated at tillering, stem elongation and heading stage on wheat cultivars BR-18 Terena, more tolerant to frost, and BRS 194, less tolerant. The response variables were: degree of leaf scorching symptoms at 7 days after frost; total dry weight; and grain weight. The acclimatization, before frost, decreased the damage caused on wheat heading stage, which resulted in less leaf scorching symptoms and higher grain yield. Temperature of -7°C, at heading stage, resulted in grain set failure in both cultivars; and frost damage was lower in plants with nine days without irrigation. Prevailing conditions before frost influence frost damage.

Eunice Portela da, Silva; Gilberto Rocca da, Cunha; João Leonardo Fernandes, Pires; Genei Antonio, Dalmago; Aldemir, Pasinato.

1257-12-01

116

Suscetibilidade magnética do solo e estimação da capacidade de suporte à aplicação de vinhaça / Soil magnetic susceptibility for estimating the support capacity to vinasse application  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese O objetivo deste trabalho foi avaliar a eficiência da suscetibilidade magnética do solo para estimar a capacidade de suporte de áreas à aplicação de vinhaça. Foram coletadas 241 amostras de solo, de uma área de 380 ha, nas quais foram determinados os atributos químicos, os teores de argila e a susce [...] tibilidade magnética do solo. Foram calculadas as doses de vinhaça recomendadas para cada amostra. Os dados foram submetidos à análise estatística descritiva, e foram desenvolvidos modelos de regressão entre a suscetibilidade magnética e os outros atributos avaliados. A análise da dependência espacial dos dados foi feita com uso da geoestatística. Foram construídos mapas de krigagem e variogramas cruzados, para averiguar a correlação espacial entre a suscetibilidade magnética e os atributos estudados. Com base no mapa de recomendação de vinhaça, nas classes de solo e nos mapas de krigagem, foram calculadas as doses médias de vinhaça e as capacidades de suporte médias, ponderadas pela área. A suscetibilidade magnética apresenta correlação espacial linear significativa com as doses de vinhaça recomendadas e com a capacidade de suporte do solo à aplicação desse efluente, e pode ser utilizada como componente da função de pedotransferência, na quantificação indireta da capacidade de suporte. Abstract in english The objective of this work was to evaluate the magnetic susceptibility efficiency for estimating the support capacity of areas for vinasse application. Two hundred forty-one soil samples were collected from a 380-ha area, on which soil chemical properties, clay content, and magnetic susceptibility w [...] ere determined. Vinasse requirement was calculated for each sample. Data were subjected to descriptive statistical analysis, and regression models were developed between magnetic susceptibility and the other evaluated attributes. The analysis of data spatial dependence was performed using geostatistics. Kriging maps and cross variograms were built in order to investigate the spatial correlation between soil magnetic susceptibility and studied attributes. Based on the map of vinasse requirement, on the soil classes, and on the kriging map, calculations were done for average vinasse dose and average soil support capacity, weighted by the area. Magnetic susceptibility has significant linear spatial correlation with recommended vinasse doses and soil support capacity for the application of this effluent, and it can be used as a pedotransfer function for indirect quantification of soil support capacity.

Rafael Gonçalves, Peluco; José, Marques Júnior; Diego Silva, Siqueira; Gener Tadeu, Pereira; Ronny Sobreira, Barbosa; Daniel de Bortoli, Teixeira; Cássia Rita, Adame; Lucas Aguilar, Cortez.

2013-06-01

117

Gamma-ray spectrometry, electrical resistivity, and magnetic susceptibility of agricultural soils in the Northwest region of the Parana State, Brazil  

International Nuclear Information System (INIS)

Gamma-ray spectrometry, electrical resistivity, and magnetic susceptibility measurements were taken from agricultural areas near the City of Maringa, in the Northwest region of the Parana state, south Brazil, in order to characterize the spatial distribution of radionuclides (K, eU, and eTh), the apparent resistivity, and the magnetic susceptibility determined for soils. Three different types of soils are present in this agricultural area: Alfisoil, clayey texture Oxisoil, both deriving from Lower Cretaceous basalts of the Serra Geral Formation; and medium texture Oxisoil from reworked Serra Geral and Goio-Ere formations, the latter deriving from sandstones of the Upper Cretaceous Caiua Group. It could be observed that in more clayey soils both concentration of radionuclides and susceptibility values are higher than in more sandy soils, especially due to the higher adsorption in the former and to the higher availability of magnetic minerals in the latter. The average ppm and Bq Kg-1 grades for K, eU, and eTh in the areas under anthropic activity are of 1766-54.75, 0.83-10.22, and 1.78-7.27, respectively. These grades are significantly higher than those of non-occupied or non-fertilized areas (1101-34.15 K, 0.14-1.69 eU, and 1.31-5.36 eTh in ppm and Bq Kg-1, respectively.) Correlations were observed between uranium and clay, uranium and magnetic susceptibility, uranium and organic matter, and between electric resistivity and clay grades. Varied concentrationvity and clay grades. Varied concentrations of radionuclides were also observed in different fertilizer formulations applied to soy and wheat cultures. Apparent electric resistivity values between 25 and 647 Ohm.m and magnetic susceptibility values between 0.28 e 1.10 x 10-3 SI due to clay and magnetic minerals represented important soil discrimination factors in the study area that can be incorporated as easy, low-cost soil mapping tools. (author)

118

Frost heave in helium and other substances  

International Nuclear Information System (INIS)

A thermomolecular pressure associated with a thermal gradient produces the phenomenon known as 'frost heave' in moisture-containing frozen ground. Thermomolecular pressures can occur in any material. As described here it is known that frost heave or thermomolecular pressures can be exhibited by any material undergoing 'premelting,' where liquid exists at temperatures below the normal solid-liquid phase boundary. Yet, the recent work on 4He [Hiroi, et a., Phys. Rev.B 40, 6581 (1989)] is the first published study of thermomolecular pressure in nonaqueous material. The striking prominence of the effect presents advantages of further applications of thermomolecular pressure for fundamental research. This paper describes the phenomenon, outlines the theory and discusses some possible static and dynamic studies of quantum liquids

119

Beryllium oxide: a frost-preventing insulator.  

Science.gov (United States)

A method is suggested of achieving low outdoor radiative losses by low spectral emittance in the atmospheric window of 8-13 microm, which will reduce dew and frost formation on surfaces exposed to the clear sky. The use of this selectively low emittance makes it feasible to use electrically insulating materials. It is argued that lattice-based reststrahlen bands can be exploited for this purpose. The observation is made that hexagonal beryllium oxide has a strong reststrahlen band that covers most of the primary atmospheric window. Results from experiments with polycrystalline samples demonstrate that bulk beryllium oxide is equally effective for dew and frost prevention as glass coated with conducting tin oxide. PMID:19770941

Ribbing, C G

1990-08-15

120

Genetic engineering: frost damage trial halted.  

Science.gov (United States)

The University of California at Berkeley has announced the postponement of a planned experiment involving the field testing of bacteria genetically engineered to reduce frost damage to crops. The action came after Jeremy Rifkin, who had earlier filed suit against the National Institutes of Health after its Recombinant DNA Advisory Committee had approved the experiment, threatened to seek a temporary restraining order against the university to halt the experiment. PMID:6578420

Budiansky, S

121

Frost formation under different gaseous atmospheres  

International Nuclear Information System (INIS)

Rates of water frost growth in a vessel with a cooled horizontal plate were experimentally determined under reduced pressure atmospheres of hydrogen, helium, methane and nitrogen. The mass deposited on the cooled surface under each of the atmospheres was almost in proportion to time. The Sherwood number under the condition of no mist formation, Sh0, in the atmospheres of methane and nitrogen was in good agreement with Catton's equation for natural convection between horizontal parallel plates. Sh0 in a hydrogen atmosphere was unity, which corresponds to control by molecular diffusion in the stagnant gas. The tendency of the decrease in Sh due to mist formation could be evaluated well by multiplying Sh0 by a factor ?CSM. The ?CSM value was calculated based on the critical supersaturation model as a function of the two interface temperatures and the total pressure. Frost growth rates under each atmosphere were in proportion to [(TS1-TW1)t/(1+1/AS1)]0.5. The proportional constant for hydrogen was greater than that for any other tested gas. Agreement and disagreement of the frost effective thermal conductivity with previous models were discussed. (author)

122

Evaluation and refinement of sprinkler application rate models used in frost protection  

Energy Technology Data Exchange (ETDEWEB)

Two models of the sprinkled orchard which predict the application rates required for successful frost protection were evaluated. A Sprinkling Application Rate (SPAR79) model, used the heat budget approach to determine the rate of heat lost by the plant part through radiative, convective, and latent heat transfer processes at the actual plant part temperature and at the plant part's critical temperature. The difference between these two rates of heat loss is the rate at which heat must be added by the latent heat of fusion liberated as the applied water freezes. This model added consideration of humidity and ice accumulation to a refinement of the heat budget configuration of earlier models. It showed that humidity is not a contributing factor in the determination of application rates. Ice accumulation was shown to decrease the required application rate by 67% when it increased the characteristic plant part size from 0.2 to 2.0 cm. A distribution factor, a component of a factor previously only estimated, was shown to increase by 30% (from 1.0 to 1.3) as blossom and leaf development progressed. Pulsed sprinkling for frost protection was carried out during six frost nights. Blossom temperatures, application rate, pulsing cycle, wind speed and air temperature were simultaneously recorded. These observations illustrated that in order to provide adequate protection an appropriate application rate and pulsing cycle must be provided by the model. It was concluded that by varying the distribution factor through the growing season and varying the application rate through a single frost night by pulsing, according to atmospheric parameters and ice accumulation, a significant decrease in amount of water applied may be realized. This decrease in water applied will alleviate ice buildup, water cost, soil drainage and nutrient leaching problems associated with sprinkling for frost protection.

Perry, K.B.

1979-01-01

123

Modelling apple flower and fruit damage to frost  

OpenAIRE

Good quality apples are grown in relatively cold areas. However, frost frequently causes damage to flowers and small fruits. When the percentage of frost damage losses is higher than the thinning requirement of the cultivar, production is reduced. In addition to reducing yield, frost damage to the skin and malformation of the fruits often devalues the quality and reduces profits. Critical temperature tables in relation to phenological stage are available for apples and other deciduous crop...

Abreu, J. P. Melo E.; Ribeiro, A. C.; Snyder, R. L.

2004-01-01

124

Effect of Fusarium oxysporum f. sp. lycopersici on the soil-to-root translocation of heavy metals in tomato plants susceptible and resistant to the fungus.  

Science.gov (United States)

The purpose of this work was to gain an insight on the potential role of the phytopathogenic fungus Fusarium oxysporum f. sp. lycopersici in the translocation of metals and metalloids from soil to plant roots in tomato (Lycopersicum esculentum). Two varieties of tomato (one susceptible and another resistant to infection by Fusarium oxysporum f. sp. lycopersici) were challenged with the fungus for different periods of time, and several elements (V, Cr, Mn, Co, Cu, Zn, As, Se, Mo, Ag, Cd, Pb) were determined in roots and in soil substrate. Additionally, phenolic plant products were also analyzed for the evaluation of the plant response to biotic stress. In order to obtain representative results for plants cultivated in noncontaminated environments, the infected and control plants were grown in commercial soil with natural, relatively low metal concentrations, partly associated with humic substances. Using such an experimental design, a specific role of the fungus could be observed, while possible effects of plant exposure to elevated concentrations of heavy metals were avoided. In the infected plants of two varieties, the root concentrations of several metals/metalloids were increased compared to control plants; however, the results obtained for elements and for phenolic compounds were significantly different in the two plant varieties. It is proposed that both Lycopersicum esculentum colonization by Fusarium oxysporum f. sp. lycopersici and the increase of metal bioavailability due to fungus-assisted solubilization of soil humic substances contribute to element traffic from soil to roots in tomato plant. PMID:21053907

Corrales Escobosa, Alma Rosa; Wrobel, Katarzyna; Landero Figueroa, Julio Alberto; Gutíerrez Corona, J Felix; Wrobel, Kazimierz

2010-12-01

125

Statistical Examination of Frost Characterization: A Case of Global Warming Impact in Jordan  

OpenAIRE

Radiation and advection frost are common in Jordan as well as other neighboring countries as they face several frost waves each year during the late months of winter. Recently, many frost episodes hit the valley and damaged the crops that were compensated by millions of dollars by the Jordanian Government. This manuscript addresses and characterizes frost, and assesses the role of global warming in impacting frost in terms of its frequency, severity, and total number of frost days per year. A...

Hamdi, Moshrik R.; Mahmoud Abu Alaban; Mohammed Jaber

2011-01-01

126

Geophysical Implications of Enceladus' CO2 Frost  

Science.gov (United States)

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

127

Suitability aero-geophysical methods for generating conceptual soil maps and their use in the modeling of process-related susceptibility maps  

Science.gov (United States)

In the past years, several times large-scale disasters occurred in Austria, which were characterized not only by flooding, but also by numerous shallow landslides and debris flows. Therefore, for the purpose of risk prevention, national and regional authorities also require more objective and realistic maps with information about spatially variable susceptibility of the geosphere for hazard-relevant gravitational mass movements. There are many and various proven methods and models (e.g. neural networks, logistic regression, heuristic methods) available to create such process-related (e.g. flat gravitational mass movements in soil) suszeptibility maps. But numerous national and international studies show a dependence of the suitability of a method on the quality of process data and parameter maps (f.e. Tilch & Schwarz 2011, Schwarz & Tilch 2011). In this case, it is important that also maps with detailed and process-oriented information on the process-relevant geosphere will be considered. One major disadvantage is that only occasionally area-wide process-relevant information exists. Similarly, in Austria often only soil maps for treeless areas are available. However, in almost all previous studies, randomly existing geological and geotechnical maps were used, which often have been specially adapted to the issues and objectives. This is one reason why very often conceptual soil maps must be derived from geological maps with only hard rock information, which often have a rather low quality. Based on these maps, for example, adjacent areas of different geological composition and process-relevant physical properties are razor sharp delineated, which in nature appears quite rarly. In order to obtain more realistic information about the spatial variability of the process-relevant geosphere (soil cover) and its physical properties, aerogeophysical measurements (electromagnetic, radiometric), carried out by helicopter, from different regions of Austria were interpreted. Previous studies show that, especially with radiometric measurements, the two-dimensional spatial variability of the nature of the process-relevant soil, close to the surface can be determined. In addition, the electromagnetic measurements are more important to obtain three-dimensional information of the deeper geological conditions and to improve the area-specific geological knowledge and understanding. The validation of these measurements is done with terrestrial geoelectrical measurements. So both aspects, radiometric and electromagnetic measurements, are important and subsequently, interpretation of the geophysical results can be used as the parameter maps in the modeling of more realistic susceptibility maps with respect to various processes. Within this presentation, results of geophysical measurements, the outcome and the derived parameter maps, as well as first process-oriented susceptibility maps in terms of gravitational soil mass movements will be presented. As an example results which were obtained with a heuristic method in an area in Vorarlberg (Western Austria) will be shown. References: Schwarz, L. & Tilch, N. (2011): Why are good process data so important for the modelling of landslide susceptibility maps?- EGU-Postersession "Landslide hazard and risk assessment, and landslide management" (NH 3.6), Vienna. [http://www.geologie.ac.at/fileadmin/user_upload/dokumente/pdf/poster/poster_2011_egu_schwarz_tilch_1.pdf] Tilch, N. & Schwarz, L. (2011): Spatial and scale-dependent variability in data quality and their influence on susceptibility maps for gravitational mass movements in soil, modelled by heuristic method.- EGU-Postersession "Landslide hazard and risk assessment, and landslide management" (NH 3.6); Vienna. [http://www.geologie.ac.at/fileadmin/user_upload/dokumente/pdf/poster/poster_2011_egu_tilch_schwarz.pdf

Tilch, Nils; Römer, Alexander; Jochum, Birgit; Schattauer, Ingrid

2014-05-01

128

Teor de carbono orgânico e a susceptibilidade à compactação de um Nitossolo e um Argissolo Organic carbon content and susceptibility to compaction of Hapludalf and Hapludox soils  

Directory of Open Access Journals (Sweden)

Full Text Available O acúmulo de matéria orgânica pode aumentar a resistência do solo à compactação, diminuindo sua magnitude ou seus efeitos. O objetivo do presente trabalho foi estudar as implicações do acúmulo de matéria orgânica no solo sobre sua susceptibilidade à compactação medida pelo coeficiente de compressão. Buscou-se estabelecer relações entre o teor de carbono orgânico e o coeficiente de compressão do solo. Utilizaram-se amostras de solo coletadas em um Argissolo Vermelho-Amarelo distrófico arênico e de um Nitossolo Vermelho distrófico latossólico, ambos contendo ampla variação do teor de carbono orgânico (CO. As amostras, com umidade equilibrada em quatro tensões de água, foram submetidas ao ensaio de adensamento uniaxial confinado, mediante cargas normais de 12,5, 25, 50, 100, 200, 400, 800 e 1600 kPa e se determinando o coeficiente de compressão plástica; definiram-se, também, o teor de carbono orgânico, a densidade do solo, a porosidade e o grau de saturação com água das amostras. O teor de carbono orgânico afeta o coeficiente de compressão do solo; no entanto, a magnitude e o tipo de efeito são dependentes da textura do solo e de seus efeitos sobre a retenção de água, a coesão e a densidade do solo.Organic matter accumulation can increase soil resistance to compaction, decreasing the compaction magnitude or its effects. The objective of this study was to establish the effect of soil organic matter accumulation on the compressibility index, which corresponds to soil susceptibility to compaction. The study was performed using samples collected from a Hapludalf and a Hapludox soils in southern Brazil, both having a significant variation in soil organic carbon (SOC content. Soil compressibility tests were performed under confined conditions, in a uniaxial apparatus by using normal loads of 12.5, 25, 50, 100, 200, 400, 800 and 1600 kPa, and the compressibility index (Cc was calculated. Soil organic carbon content, bulk density, porosity and water saturation degree were determined too. Results show that soil organic matter content affects the soil compressibility index, however the magnitude and type of effect are dependent upon soil texture and effects associated to soil water retention, cohesion, and bulk density.

João A. Braida

2010-02-01

129

Teor de carbono orgânico e a susceptibilidade à compactação de um Nitossolo e um Argissolo / Organic carbon content and susceptibility to compaction of Hapludalf and Hapludox soils  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese O acúmulo de matéria orgânica pode aumentar a resistência do solo à compactação, diminuindo sua magnitude ou seus efeitos. O objetivo do presente trabalho foi estudar as implicações do acúmulo de matéria orgânica no solo sobre sua susceptibilidade à compactação medida pelo coeficiente de compressão. [...] Buscou-se estabelecer relações entre o teor de carbono orgânico e o coeficiente de compressão do solo. Utilizaram-se amostras de solo coletadas em um Argissolo Vermelho-Amarelo distrófico arênico e de um Nitossolo Vermelho distrófico latossólico, ambos contendo ampla variação do teor de carbono orgânico (CO). As amostras, com umidade equilibrada em quatro tensões de água, foram submetidas ao ensaio de adensamento uniaxial confinado, mediante cargas normais de 12,5, 25, 50, 100, 200, 400, 800 e 1600 kPa e se determinando o coeficiente de compressão plástica; definiram-se, também, o teor de carbono orgânico, a densidade do solo, a porosidade e o grau de saturação com água das amostras. O teor de carbono orgânico afeta o coeficiente de compressão do solo; no entanto, a magnitude e o tipo de efeito são dependentes da textura do solo e de seus efeitos sobre a retenção de água, a coesão e a densidade do solo. Abstract in english Organic matter accumulation can increase soil resistance to compaction, decreasing the compaction magnitude or its effects. The objective of this study was to establish the effect of soil organic matter accumulation on the compressibility index, which corresponds to soil susceptibility to compaction [...] . The study was performed using samples collected from a Hapludalf and a Hapludox soils in southern Brazil, both having a significant variation in soil organic carbon (SOC) content. Soil compressibility tests were performed under confined conditions, in a uniaxial apparatus by using normal loads of 12.5, 25, 50, 100, 200, 400, 800 and 1600 kPa, and the compressibility index (Cc) was calculated. Soil organic carbon content, bulk density, porosity and water saturation degree were determined too. Results show that soil organic matter content affects the soil compressibility index, however the magnitude and type of effect are dependent upon soil texture and effects associated to soil water retention, cohesion, and bulk density.

João A., Braida; José M., Reichert; Dalvan J., Reinert; Milton da, Veiga.

2010-02-01

130

Geochemical association of Pu and Am in selected host-phases of contaminated soils from the UK and their susceptibility to chemical and microbiological leaching.  

Science.gov (United States)

Understanding the biogeochemical behaviour and potential mobility of actinides in soils and groundwater is vital for developing remediation and management strategies for radionuclide-contaminated land. Pu is known to have a high Kd in soils and sediments, however remobilization of low concentrations of Pu remains a concern. Here, some of the physicochemical properties of Pu and the co-contaminant, Am, are investigated in contaminated soils from Aldermaston, Berkshire, UK, and the Esk Estuary, Cumbria, UK, to determine their potential mobility. Sequential extraction techniques were used to examine the host-phases of the actinides in these soils and their susceptibility to microbiological leaching was investigated using acidophilic sulphur-oxidising bacteria. Sequential extractions found the majority of (239,240)Pu associated with the highly refractory residual phase in both the Aldermaston (63.8-85.5 %) and Esk Estuary (91.9-94.5%) soils. The (241)Am was distributed across multiple phases including the reducible oxide (26.1-40.0%), organic (45.6-63.6%) and residual fractions (1.9-11.1%). Plutonium proved largely resistant to leaching from microbially-produced sulphuric acid, with a maximum 0.18% leached into solution, although up to 12.5% of the (241)Am was leached under the same conditions. If Pu was present as distinct oxide particles in the soil, then (241)Am, a decay product of Pu, would be expected to be physically retained in the particle. The differences in geochemical association and bioleachability of the two actinides suggest that this is not the case and hence, that significant Pu is not present as distinct particles. These data suggest the majority of Pu in the contaminated soils studied is highly recalcitrant to geochemical changes and is likely to remain immobile over significant time periods, even when challenged with aggressive "bioleaching" bacteria. PMID:25659921

Kimber, Richard L; Corkhill, Claire L; Amos, Sean; Livens, Francis R; Lloyd, Jonathan R

2015-04-01

131

Risk analysis of first and last frost occurrences in the Central Alborz region, Iran  

Science.gov (United States)

Central Alborz is one of the important agricultural regions of Iran. Occurrence of the first frost in fall and the last frost in spring causes damage to the crops in this region every year. Information about the probable dates of frost occurrence helps farmers in preventing or reducing the damages caused by frost. Six stations, with 34 years of daily minimum temperature data, were selected at various elevations. Dates of frost occurrences in three degrees of severity (mild, moderate, and severe) and frost-free periods were obtained for each year. Appropriate distributions were determined for each frost series (dates of frosts and frost-free periods) on the basis of relevant statistical methods. It was found that the Pearson type III distribution was most appropriate. Probability distribution was constructed for each frost series. Frost occurrences up to a given date and maximum lengths of frost-free periods, with their probabilities, were determined. Correlations between the dates of frost occurrence and elevation, and between the maximum lengths of frost-free periods and elevation were identified in some probability levels. Our results show a positive correlation between the frequency of frost and elevation, and a significant negative correlation between the duration of frost-free period and elevation. Frost is more frequent in higher areas. The shortest and the longest frost-free periods occur on top of high mountains and on low altitude areas, respectively.

Rahimi, M.; Hajjam, S.; Khalili, A.; Kamali, G. A.; Stigter, C. J.

2007-03-01

132

Simulated frost effects on cool-season grass carbohydrate levels  

Science.gov (United States)

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...

133

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

Science.gov (United States)

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

134

Frost formation on an airfoil: A mathematical model 1  

Science.gov (United States)

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

135

How endangered is sexual reproduction of high-mountain plants by summer frosts? Frost resistance, frequency of frost events and risk assessment  

OpenAIRE

In temperate-zone mountains, summer frosts usually occur during unpredictable cold spells with snow-falls. Earlier studies have shown that vegetative aboveground organs of most high-mountain plants tolerate extracellular ice in the active state. However, little is known about the impact of frost on reproductive development and reproductive success. In common plant species from the European Alps (Cerastium uniflorum, Loiseleuria procumbens, Ranunculus glacialis, Rhododendron ferrugineum, Saxif...

Ladinig, Ursula; Hacker, Ju?rgen; Neuner, Gilbert; Wagner, Johanna

2013-01-01

136

Mathematical modeling of heat transfer between the plant seedling and the environment during a radiation frost  

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Full Text Available The power of the internal heat source sufficient to maintain a positive temperature of plants during one of the possible form of cold stress - radiation frost was determined with the help of numerical simulation.The simulation of unsteady heat transfer in the soil-plant-air system in the conditions of radiation frost showed that the the ground part of plants is cooling most rapidly, and this process is partially slowed down by the natural-convection heat transfer with warmer air. If the frost is not continuous, the radiative cooling is the main danger for plant. The necessary power of heat-production inside plant that allows it to avoid hypothermia depends both on natural conditions and the size of the plant. For plants with a typical diameter of the stem about 2 mm this heat-production should be from 50 to 100 W / kg. Within 2 hours a total amount of heat about 0.5 MJ / kg in the plant should be allocated. Larger plants will have a smaller surface to mass ratio, and the maintaining of it's temperature will require a lower cost of nutrients per unit, accordingly. Modeling of the influence of plant surface trichomes presence on the process of its cooling showed that the role of trichomes in the protection of plants from hypothermia during radiation frost usually is negative due to the fact that the presence of trichomes increases the radiative heat transfer from the plant and the impediment in air movement near the plant reduces heat flux entering the plant from a warmer air. But in cases where the intensity of heat generation within the plant is sufficient for the maintenance of the plant temperature higher than the air temperature, the presence of trichomes impairs heat transfer from plant to air, and therefore contributes to a better heating of plants.

Finnikov K.A.

2010-11-01

137

Mechanism of frost damage to concrete  

Science.gov (United States)

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 the contributions of thermal expansion, pore pressure, and crystallization pressure of ice to the strain observed in a mortar during freezing/thawing cycles. Air-entrained mortars contract upon freezing due to the cryo-suction effect, while non-air-entrained mortars expand primarily due to hydraulic pressure. Based on the theory originally proposed by Powers and Helmuth, we show that the poromechanical calculations account quantitatively for the contraction of samples with air entrainment, which is shown to quantitatively account for a reduction of salt scaling damage based on the glue-spall theory. The method of thermoporometry (TPM) that we used to study the pore structure of concrete is also discussed. In a study of ice propagation inside concrete, we re-examined experiments by Helmuth [Proc. 4th Int. Cong. Chem. Cement, NBS Monog. 43, Vol. II (National Bureau of Standards, Washington, D.C., 1962) pp. 855--869] from which he concluded that ice grows in the pores of cement paste under heat-flow control, and that the internal temperature rises to the melting point given by the Gibbs-Thomson equation. Using experimental and computational methods, we find that his conclusions are correct, but the growth rates he reports are misleading. Our experiment reveals the true growth rate, which is about three times smaller than found by Helmuth. The dendritic morphology explains how fast constant growth rates can occur when the interior temperature of the sample is very near the melting point: the temperature at the tip of the dendrite is a few degrees below the melting point, but the liquid behind the tip (between adjacent dendrites) is at the melting point. The implications of this type of growth for frost damage are discussed.

Sun, Zhenhua

138

Identifying and Mapping Seasonal Surface Water Frost with MGS TES  

Science.gov (United States)

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

139

Patterns of late spring frost leaf damage and recovery in a European beech (Fagus sylvatica L.) stand in south-eastern Germany based on repeated digital photographs  

Science.gov (United States)

Damage by late spring frost is a risk deciduous trees have to cope with in order to optimize the length of their growing season. The timing of spring phenological development plays a crucial role, not only at the species level, but also at the population and individual level, since fresh new leaves are especially vulnerable. For the pronounced late spring frost in May 2011 in Germany, we studied the individual leaf development of 35 deciduous trees (mainly European beech Fagus sylvatica L.) at a mountainous forest site in the Bayerischer Wald National Park using repeated digital photographs. Analyses of the time series of greenness by a novel Bayesian multiple change point approach mostly revealed five change points which almost perfectly matched the expected break points in leaf development: (i) start of the first greening between day of the year (DOY) 108–119 (mean 113), (ii) end of greening, and (iii) visible frost damage after the frost on the night of May 3rd/4th (DOY 123/124), (iv) re-sprouting 19–38 days after the frost, and (v) full maturity around DOY 178 (166–184) when all beech crowns had fully recovered. Since frost damage was nearly 100%, individual susceptibility did not depend on the timing of first spring leaf unfolding. However, we could identify significant patterns in fitness linked to an earlier start of leaf unfolding. Those individuals that had an earlier start of greening during the first flushing period had a shorter period of recovery and started the second greening earlier. Thus, phenological timing triggered the speed of recovery from such an extreme event. The maximum greenness achieved, however, did not vary with leaf unfolding dates. Two mountain ashes (Sorbus aucuparia L.) were not affected by the low temperatures of -5°C. Time series analysis of webcam pictures can thus improve process-based knowledge and provide valuable insights into the link between phenological variation, late spring frost damage, and recovery within one stand. PMID:25759707

Menzel, Annette; Helm, Raimund; Zang, Christian

2015-01-01

140

Patterns of late spring frost leaf damage and recovery in a European beech (Fagus sylvatica L.) stand in south-eastern Germany based on repeated digital photographs.  

Science.gov (United States)

Damage by late spring frost is a risk deciduous trees have to cope with in order to optimize the length of their growing season. The timing of spring phenological development plays a crucial role, not only at the species level, but also at the population and individual level, since fresh new leaves are especially vulnerable. For the pronounced late spring frost in May 2011 in Germany, we studied the individual leaf development of 35 deciduous trees (mainly European beech Fagus sylvatica L.) at a mountainous forest site in the Bayerischer Wald National Park using repeated digital photographs. Analyses of the time series of greenness by a novel Bayesian multiple change point approach mostly revealed five change points which almost perfectly matched the expected break points in leaf development: (i) start of the first greening between day of the year (DOY) 108-119 (mean 113), (ii) end of greening, and (iii) visible frost damage after the frost on the night of May 3rd/4th (DOY 123/124), (iv) re-sprouting 19-38 days after the frost, and (v) full maturity around DOY 178 (166-184) when all beech crowns had fully recovered. Since frost damage was nearly 100%, individual susceptibility did not depend on the timing of first spring leaf unfolding. However, we could identify significant patterns in fitness linked to an earlier start of leaf unfolding. Those individuals that had an earlier start of greening during the first flushing period had a shorter period of recovery and started the second greening earlier. Thus, phenological timing triggered the speed of recovery from such an extreme event. The maximum greenness achieved, however, did not vary with leaf unfolding dates. Two mountain ashes (Sorbus aucuparia L.) were not affected by the low temperatures of -5°C. Time series analysis of webcam pictures can thus improve process-based knowledge and provide valuable insights into the link between phenological variation, late spring frost damage, and recovery within one stand. PMID:25759707

Menzel, Annette; Helm, Raimund; Zang, Christian

2015-01-01

141

Characteristics of heat pump system operating with frost formation  

International Nuclear Information System (INIS)

This paper reports on the performance of heat pump system operating with frost formation that was predicted related to the change of the performance of evaporator due to frosting. The predicted results were compared with the experimental results using a cross-finned tube evaporator. The poor performance of evaporator due to frosting causes the decrease in the heating capacity as the results of the drop of the evaporating temperature and the decrease in the flow rate of refrigerant. The calculated results were in agreement with the experimental results

142

Nitrogen frost migration on Triton: A historical model  

International Nuclear Information System (INIS)

The author presents the results of numerical simulations of the seasonal migration of nitrogen frost on Triton, constrained by Voyager observations of atmospheric pressure, temperature, and albedo distribution. Most of the exposed nitrogen is probably seasonal frost, whose migration can produce major variations in atmospheric pressure. For instance, models explored here predict a tenfold pressure drop in the coming decade. The observed albedo patterns can be understood if fresh nitrogen frost is relatively dark butt brightens with increasing insolation in a manner analogous to the Martian southern CO2 cap

143

Modelos de paisagem e susceptibilidade magnética na identificação e caracterização do solo / Landscape models and magnetic susceptibility on soil identification and characterization  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese O conhecimento detalhado do solo e de seus atributos, ao longo da paisagem, é uma demanda permanente dos sistemas urbanos e agroindustriais, para o planejamento sustentável de uso e ocupação. O presente trabalho objetivou estudar o potencial de modelos de paisagem e susceptibilidade magnética na ide [...] ntificação e caracterização de latossolos, em Guariba (SP). Foram coletadas 514 amostras de solo, em 110,0 ha, às profundidades de 0,0-0,20 m e 0,60-0,80 m. Foram identificados diferentes compartimentos de paisagem, com base no modelo de superfície geomórfica e segmento de vertente. Em cada compartimento de paisagem, foram abertas trincheiras, para classificação do solo. As amostras foram analisadas quanto à granulometria e atributos químicos, pH (água, CaCl2 e KCl), matéria orgânica, P extraível, K+, Ca2+, Mg2+ e H+ + Al3+. Também foram determinados os teores de SiO2, Al2O3, Fe2O3 e óxidos de Fe livres (Fe d) e pouco cristalizados (Fe o), nas amostras das trincheiras, além da susceptibilidade magnética (SM). Solos taxonomicamente iguais, porém em diferentes compartimentos da paisagem, apresentaram valores distintos, para os atributos estudados, indicando que os modelos de paisagem e a susceptibilidade magnética podem ser viáveis, como técnica de campo, para auxiliar no detalhamento da variação dos atributos do solo. A susceptibilidade magnética demonstrou ter potencial para delimitação das superfícies geomórficas mapeadas no campo, o que indica o seu potencial de uso, na identificação e caracterização de áreas mais homogêneas. Abstract in english The detailed knowledge of soils and their attributes, across the landscape, is a permanent demand of urban and agro-industrial systems, for planning their sustainable use and occupation. This study aimed at evaluating the potential of landscape models and the magnetic susceptibility in the identific [...] ation and characterization of oxisols, in Guariba, São Paulo State, Brazil. A total of 514 soil samples were collected in 110.0 ha, at the depths of 0.0-0.20 m and 0.60-0.80 m. Different landscape compartments, based on the geomorphic surface and segment slope models, were identified. In each landscape compartment, trenches were opened for soil classification. The samples were analyzed for particle size and chemical properties, pH (water, CaCl2 and KCl), organic matter, extractable P, K+, Ca2+, Mg2+ and H+ + Al3+. The contents of SiO2, Al2O3, Fe2O3 and free (Fe d) and slightly crystallized (Fe o) Fe oxides were determined in samples from the trenches, as well as the magnetic susceptibility (MS). Taxonomically similar soils, but in different landscape compartments, presented different values for the attributes studied, indicating that the landscape models and magnetic susceptibility may be viable, as a field technique, to help detailing the variation of soil attributes. The magnetic susceptibility showed potential for delimiting geomorphic surfaces mapped in the field, emphasizing its potential use for identifying and characterizing homogeneous areas.

Sammy Sidney Rocha, Matias; José, Marques Júnior; Diego Silva, Siqueira; Gener Tadeu, Pereira.

2013-03-01

144

Effect of variations in air speed on cross-flow cylinder frosting  

International Nuclear Information System (INIS)

In this paper the effect of fluctuating air speed on frost growth and heat transfer to a cylinder in cross-flow is discussed. Frost-growth of up to 20 hours is simulated using an experimentally validated finite difference computer model. Graphical results are presented for frost mass, frost depth, frost surface temperature and heat transfer versus time under both steady and fluctuating air speed conditions. In general, it is found that a thinner, more dense frost layer develops under fluctuating air speed conditions giving improved heat transfer. This phenomenon may be explained by the increased frequency of frost surface thaw/freeze cycles when fluctuating air speed conditions prevail

145

Susceptibility Testing  

Science.gov (United States)

... Testing; Drug Resistance Testing; Culture and Sensitivity; C & S; Antimicrobial Susceptibility Formal name: Bacterial and Fungal Susceptibility Testing Related tests: Urine Culture ; Blood Culture ; Bacterial Wound Culture ; AFB ...

146

Relationship between frost hardiness of adults and seedlings of different tree species  

OpenAIRE

The aim of this study was to investigate the relationship between frost hardiness and the macroclimatic niche of adult individuals and seedlings of eight temperate tree species. Frost damage was investigated on winter buds and needles of adult individuals and on freshly germinated seedlings. We hypothesized that frost hardiness of adult individuals and seedlings is in accordance with their macroclimatic niche and that frost hardiness of seedlings increases with increasing plant age. Frost har...

Hofmann M; Jager M; Bruelheide H

2014-01-01

147

A method for assessing frost damage risk in sweet cherry orchards of South Patagonia  

OpenAIRE

Quantification of frost damage risk is important in planning the development of new orchard areas and for decision-making on design and installation of frost control systems. The objective of this study was to develop a comprehensive method to quantify frost damage risk in different sweet cherry production areas of South Patagonia and to estimate the potential impact of frost control systems on risk reduction. Lack of historical weather data required a theoretical-empirical approach. Frost da...

Cittadini, E. D.; Ridder, N.; Peri, P. L.; Keulen, H.

2006-01-01

148

Risk analysis of first and last frost occurrences in central Alborz region, Iran  

OpenAIRE

Central Alborz is one of the important agricultural regions of Iran. Occurrence of the first frost in fall and the last frost in spring causes damage to the crops in this region every year. Information about the probable dates of frost occurrence helps farmers in preventing or reducing the damages caused by frost. Six stations, with 34 years of daily minimum temperature data, were selected at various elevations. Dates of frost occurrences in three degrees of severity (mild, moderate, and seve...

Rahimi, M.; Khalili, A.; Hajjam, S.; Kamali, G. A.; Stigter, C. J.

2007-01-01

149

Prediction of Frost Risks and Plagues using WRF model: a Port Wine region case study  

Science.gov (United States)

In viticulture where the quality of the wine, the selection of the grapevines or even the characteristics of the farming soil, also depending from local soil features like topography, proximity of a river or water body, will act locally on the weather. Frosts are of significant concern to growers of many cultures crops such as winegrapes. Because of their high latitude and some altitude, the vineyards of the Demarcated Douro Region (DDR) are subjected to the frost, which cause serious damages. But the hazards of vineyard don't confine to the incidents of the fortuitous and meteorological character. The illnesses and plagues affect frequently the vineyards of Demarcated Douro Region due, namely to the weather, to the high power of the regional stocks, to the dense vegetation badly drained and favourable to the setting of numberless fungi, viruses and/or poisonous insects. In the case of DDR it is worth noticing the meteorological conditions due to the weather characteristics. Although there are several illnesses and plagues the most important enemies for the vine in the DDR are the mildew, oidium, grey rottenness, grape moth,. . . , if the climatic conditions favour their appearance and development. For this study, we selected some months for different periods, at the 16 weather stations of the Region of Douro. We use the Weather Research and Forecast Model (WRF) to study and possibly predict the occurrence of risk and plagues (mildew) episodes. The model is first validated with the meteorological data obtained at the weather stations. The knowledge of frost and plagues occurrence allows one to decrease its risks not only by selecting the cultural species and varieties but also the places of growth and the planting and sowing dates.

Rodrigues, M. A.; Rocha, A.; Monteiro, A.; Quénol, H.; de Freitas, J. R.

2012-04-01

150

Internal frost damage in concrete - experimental studies of destruction mechanisms  

OpenAIRE

The aim of the study was to identify mechanisms acting at internal frost destruction of concrete. By 'internal frost destruction' is meant damage caused inside concrete that is moisture insulated from the surroundings, i.e. when no moisture exchange with the surroundings is possible during freeze-thaw. Thus, the aim was not to investigate destruction processes (scaling) taking place at the surface of concrete exposed to water or salt solution. The aim should be reached by experimental...

Fridh, Katja

2005-01-01

151

Moisture Conditions and Frost Resistance of Concrete in Hydraulic Structures  

OpenAIRE

Owing to the winter conditions in Sweden, the effects of frost action may have a considerable impact on the deterioration of concrete. Both superficial and internal damage, which are suspected to have been caused by frost action, have been found in concrete in hydraulic structures. These observations have raised questions about the long-term behaviour of hydraulic structures in cold regions. Superficial damage, similar in appearance to salt scaling of concrete, can be seen at the water...

Rosenqvist, Martin

2013-01-01

152

Frost protection: fundamentals, practice and economics. Volume 1  

OpenAIRE

This book describes the physics and biology of frost occurrence and damage, passive and active protection methods and how to access the cost-effectiveness of active protection techniques. Night-time energy balanceis used to demonstrate how protection methods are used to reduce the likelihood of frost damage.Simple methods and programs are provided to help predict temperature trends and to help determine the timing for active methods. Plant physiology related to freeze damage and critical dama...

Snyder, Richard L.; Melo-abreu, J. Paulo

2005-01-01

153

Gamma-ray spectrometry, electrical resistivity, and magnetic susceptibility of agricultural soils in the Northwest region of the Parana State, Brazil; Gamaespectrometria, resistividade eletrica e susceptibilidade magnetica de solos agricolas no noroeste do estado do Parana  

Energy Technology Data Exchange (ETDEWEB)

Gamma-ray spectrometry, electrical resistivity, and magnetic susceptibility measurements were taken from agricultural areas near the City of Maringa, in the Northwest region of the Parana state, south Brazil, in order to characterize the spatial distribution of radionuclides (K, eU, and eTh), the apparent resistivity, and the magnetic susceptibility determined for soils. Three different types of soils are present in this agricultural area: Alfisoil, clayey texture Oxisoil, both deriving from Lower Cretaceous basalts of the Serra Geral Formation; and medium texture Oxisoil from reworked Serra Geral and Goio-Ere formations, the latter deriving from sandstones of the Upper Cretaceous Caiua Group. It could be observed that in more clayey soils both concentration of radionuclides and susceptibility values are higher than in more sandy soils, especially due to the higher adsorption in the former and to the higher availability of magnetic minerals in the latter. The average ppm and Bq Kg{sup -1} grades for K, eU, and eTh in the areas under anthropic activity are of 1766-54.75, 0.83-10.22, and 1.78-7.27, respectively. These grades are significantly higher than those of non-occupied or non-fertilized areas (1101-34.15 K, 0.14-1.69 eU, and 1.31-5.36 eTh in ppm and Bq Kg-1, respectively.) Correlations were observed between uranium and clay, uranium and magnetic susceptibility, uranium and organic matter, and between electric resistivity and clay grades. Varied concentrations of radionuclides were also observed in different fertilizer formulations applied to soy and wheat cultures. Apparent electric resistivity values between 25 and 647 Ohm.m and magnetic susceptibility values between 0.28 e 1.10 x 10-3 SI due to clay and magnetic minerals represented important soil discrimination factors in the study area that can be incorporated as easy, low-cost soil mapping tools. (author)

Becegato, Valter Antonio [Universidade do Estado de Santa Catarina-UDESC, Centro de Ciencias Agroveterinarias, Lages, SC (Brazil); Ferreira, Francisco Jose Fonseca, E-mail: becegato@cav.udesc.br, E-mail: francisco.ferreira@ufpr.br [Universidade Federal do Parana (LPGA/UFPR), Curitiba, PR (Brazil). Dept. de Geologia. Lab. de Pesquisas em Geofisica Aplicada

2005-10-15

154

Coupling of THALES and FROST using MPI Method  

International Nuclear Information System (INIS)

This paper presents the coupling method between THALES and FROST and the simulation results with the coupled code system. In this study, subchannel analysis code THALES and transient fuel performance code FROST were coupled using MPI method as the first stage of the development of the multi-dimensional safety analysis methodology. As a part of the validation, the CEA ejection accident was simulated using the coupled THALES-FROST code and the results were compared with the ShinKori 3 and 4 FSAR. Comparison results revealed that CHASER using MPI method predicts fuel temperatures and heat flux quantitatively well. Thus it was confirmed that the THALES and FROST are properly coupled. In near future, ASTRA, multi-dimensional core neutron kinetics code, will be linked to THALESFROST code for the detailed three-dimensional CEA ejection analysis. The current safety analysis methodology for a CEA ejection accident based on numerous conservative assumptions with the point kinetics model results in quite adverse consequences. Thus, KNF is developing the multi-dimensional safety analysis methodology to enhance the consequences of the CEA ejection accident. For this purpose, three-dimensional core neutron kinetics code ASTRA, subchannel analysis code THALES, and transient fuel performance analysis code FROST are being coupled using message passing interface(MPI). For the first step, THALES and FROST are coupled and tested

155

Frost risk for overwintering crops in a changing climate  

Science.gov (United States)

Climate change scenarios predict a general increase in daily temperatures and a decline in snow cover duration. On the one hand, higher temperature in fall and spring may facilitate the development of overwintering crops and allow the expansion of winter cropping in locations where the growing season is currently too short. On the other hand, higher temperatures prior to winter crop dormancy slow down frost hardening, enhancing crop vulnerability to temperature fluctuation. Such vulnerability may be exacerbated by reduced snow cover, with potential further negative impacts on yields in extremely low temperatures. We propose a parsimonious probabilistic model to quantify the winter frost damage risk for overwintering crops, based on a coupled model of air temperature, snow cover, and crop minimum tolerable temperature. The latter is determined by crop features, previous history of temperature, and snow cover. The temperature-snow cover model is tested against meteorological data collected over 50 years in Sweden and applied to winter wheat varieties differing in their ability to acquire frost resistance. Hence, exploiting experimental results assessing crop frost damage under limited temperature and snow cover realizations, this probabilistic framework allows the quantification of frost risk for different crop varieties, including in full temperature and precipitation unpredictability. Climate change scenarios are explored to quantify the effects of changes in temperature mean and variance and precipitation regime over crops differing in winter frost resistance and response to temperature.

Vico, Giulia; Weih, Martin

2013-04-01

156

Frost-related dieback of Swedish and Estonian Salix plantations due to pathogenic and ice nucleation-active bacteria  

Energy Technology Data Exchange (ETDEWEB)

During the past decade, important dieback has been observed in short-rotation forestry plantations of Salix viminalis and S. dasyclados in Sweden and Estonia, plantations from which the isolation of ice nucleation-active (INA) and pathogenic bacteria has also been reported. This thesis investigates the connection between bacterial infection and frost as a possible cause for such damage, and the role played by internal and external factors (e.g. plant frost sensitivity, fertilisation) in the dieback observed. Bacterial floras isolated from ten Salix clones growing on fertilised/unfertilised mineral soil or nitrogen-rich organic soil, were studied. Culturable bacterial communities present both in internal necrotic tissues and on the plant surface (i.e. epiphytes) were isolated on two occasions (spring and autumn). The strains were biochemically characterised (with gram, oxidase and fluorescence tests), and tested for ice nucleation-activity. Their pathogenic properties were studied with and without association to a freezing stress. Certain strains were eventually identified with BIOLOG plates and 16S rRNA analysis. A high number of culturable bacterial strains was found in the plant samplings, belonging mainly to Erwinia and Sphingomonas spp.; pathogenic and INA communities being mostly Erwinia-, Sphingomonas- and Xanthomonas-like. The generally higher plant dieback noted in the field on nutrient-rich soils and for frost sensitive clones was found connected to higher numbers of pathogenic and INA bacteria in the plants. We thus confirm Salix dieback to be related to a synergistic effect of frost and bacterial infection, possibly aggravated by fertilisation.

Cambours, M.A.

2004-07-01

157

Suscetibilidade magnética do horizonte B de solos do Estado do Paraná Magnetic susceptibility of B horizon of soils in the State of Paraná  

Directory of Open Access Journals (Sweden)

Full Text Available Os minerais ferrimagnéticos maghemita (?Fe2O3 e magnetita (Fe3O4 possuem alta relação com a disponibilidade de cátions metálicos e com a capacidade do solo em adsorver ânions como o fosfato. Uma percentagem expressiva dos solos brasileiros apresenta magnetização espontânea. No Estado do Paraná essa área corresponde a aproximadamente 50 %. A determinação da suscetibilidade magnética por unidade de massa (?BF é o método mais simples de identificar a presença e quantificar esses minerais nos solos. A BF é uma técnica rápida, barata, não destrutiva e de boa reprodutibilidade, que pode ser utilizada como critério nos estudos pedogenéticos em que os minerais ferrimagnéticos estão presentes. O objetivo deste trabalho foi verificar a influência do material de origem nos valores de ?BF da terra fina seca ao ar (TFSA de amostras do horizonte B de solos do Paraná. As amostras foram coletadas em todo o Estado, num total de 45 pontos. Na TFSA foram determinados os valores de BF e da porcentagem da frequência dependente da suscetibilidade magnética (?FD. Os valores de suscetibilidade magnética dos solos formados sobre rochas eruptivas básicas foram significativamente maiores (1.000 a 7.800 x 10-8 m³ kg-1 que os encontrados em solos formados sobre rochas metamórficas e sedimentares (menores do que 500 x 10-8 m³ kg-1, demonstrando a influência do material de origem na presença de minerais ferrimagnéticos. Os valores de ?FD indicaram a presenca de partículas superparamagnéticas (maghemita na maioria dos solos paranaenses.The ferrimagnetic minerals maghemite (?Fe2O3 are closely related with metal availability and P adsorption capacity. Magnetization is spontaneous in a significant percentage of Brazilian soils. In the State of Paraná (Brazil this area represents up to 50 %. The determination of the mass-specific magnetic susceptibility (?BF is the simplest method of identification and quantification of ferrimagnetic minerals in soils. The ?LF is a quick, cheap, non-destructive technique, with satisfactory reproducibility, and can be used as a criterion in pedogenetic studies involving ferrimagnetic minerals. The aim of this paper was to verify the influence of parent rock material on ?LF values of air-dried fine earth of B horizon of soil samples from Paraná. The samples were collected at 45 sites across the entire State to determine the ?LF values and percentage of frequency-dependent magnetic susceptibility (?FD. The values of mass-specific magnetic susceptibility of soils formed from basic eruptive rocks were significantly higher (1,000 to 7,800 x 10-8 m³ kg-1 than of those from sedimentary and metamorphic rocks (lower than 500 x 10-8 m³ kg-1. The data show the strong influence of the parent rock material on the presence of ferrimagnetic minerals. The ?FD values indicate the presence of superparamagnetic particles (maghemite in the majority of the Paraná State soils.

Alceu Rodrigues da Silva

2010-04-01

158

?Determination of Frost Free Season by Using Dates of First and Last Advection and Radiation Frosts in Zanjan, Gazvin and Tehran Regions  

Directory of Open Access Journals (Sweden)

Full Text Available Dates of start and end of frost based on minimum shelter temperature equal to or less than 0°C were studied in Zanjan, Ghazvin and Tehran during 1961-2000. The cause of these frosts was determined by weather parameter values at observation hours and the aid of synoptic maps. Frost series based upon last spring or first fall advection are defined and found to be random and normally distributed. The "potential growing season", defined as the interval between spring last and first fall advection frosts, is found to be 29 days in Zanjan, 23 days in Ghazvin and 10 days in Tehran longer than the "growing season" defined by the interval from last spring to first fall occurrences of minimum shelter temperature of 0°C or less. The numbers of radiation frosts in the interval between first radiation frosts in fall or last radiation frost in spring and related advection frost were counted and found that this parameter is greater in Zanjan. Frostless days between the first two fall frosts and last two spring frosts show that the lengthening of spring season with one night protection is possible for 4 days in Zanjan, 6 in Gazvin and 4 in Tehran, providing that first fall and spring last frost is radiation. Results of this study permit estimating the practicality of frost protection for specialized crops in the area of study.

K Noohi

2009-01-01

159

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

Science.gov (United States)

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

160

Forecast of Frost Days Based on Monthly Temperatures  

Science.gov (United States)

Although frost can cause considerable crop damage and mitigation practices against forecasted frost exist, frost forecasting technologies have not changed for many years. The paper reports a new method to forecast the monthly number of frost days (FD) for several meteorological stations at Community of Madrid (Spain) based on successive application of two models. The first one is a stochastic model, autoregressive integrated moving average (ARIMA), that forecasts monthly minimum absolute temperature (tmin) and monthly average of minimum temperature (tminav) following Box-Jenkins methodology. The second model relates these monthly temperatures to minimum daily temperature distribution during one month. Three ARIMA models were identified for the time series analyzed with a stational period correspondent to one year. They present the same stational behavior (moving average differenced model) and different non-stational part: autoregressive model (Model 1), moving average differenced model (Model 2) and autoregressive and moving average model (Model 3). At the same time, the results point out that minimum daily temperature (tdmin), for the meteorological stations studied, followed a normal distribution each month with a very similar standard deviation through years. This standard deviation obtained for each station and each month could be used as a risk index for cold months. The application of Model 1 to predict minimum monthly temperatures showed the best FD forecast. This procedure provides a tool for crop managers and crop insurance companies to asses the risk of frost frequency and intensity, so that they can take steps to mitigate against frost damage and estimated the damage that frost would cost. This research was supported by Comunidad de Madrid Research Project 076/92. The cooperation of the Spanish National Meteorological Institute and the Spanish Ministerio de Agricultura, Pesca y Alimentation (MAPA) is gratefully acknowledged.

Castellanos, M. T.; Tarquis, A. M.; Morató, M. C.; Saa-Requejo, A.

2009-04-01

161

Frost Multidimensional Perfectionism Scale: the portuguese version / Frost Multidimensional Perfectionism Scale: versão portuguesa  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese CONTEXTO: A Escala Multidimensional de Perfeccionismo de Frost (FMPS) é uma das escalas mais usadas em todo o mundo para avaliar o perfeccionismo. OBJETIVO: Analisar as características psicométricas da versão portuguesa da FMPS. MÉTODOS: A amostra foi constituída por 217 estudantes do ensino superio [...] r (178 mulheres). Um subgrupo (n = 166) completou o reteste após quatro semanas. RESULTADOS: A consistência interna da escala mostrou ser elevada (alfa de Cronbach = ,857). As correlações item-total corrigido variaram entre ,019 e ,548. Os resultados também sugeriram uma boa estabilidade temporal da escala, sendo a correlação teste-reteste de ,765. Foi realizada a análise das componentes principais com rotação Varimax e com base no Scree plot foram extraídas duas soluções fatoriais robustas (quatro e seis fatores). A análise paralela (Monte Carlo PCA) confirmou a solução de seis fatores. A validade concorrente com a escala MPS de Hewitt e Flett foi elevada, assim como a sua capacidade discriminante dos afetos positivos e negativos (Perfil de Estados de Humor - POMS). CONCLUSÃO: As duas estruturas fatoriais (quatro e seis fatores) encontradas na versão portuguesa da Escala Multidimensional de Perfeccionismo de Frost replicam os resultados obtidos por diferentes autores, em diferentes amostras e culturas. Esse fato sugere que essa escala é um instrumento robusto para a avaliação do perfeccionismo em vários contextos, clínicos e de investigação, bem como em estudos transculturais. Abstract in english BACKGROUND: The Frost Multidimensional Perfectionism Scale is one of the most world widely used measures of perfectionism. OBJECTIVE: To analyze the psychometric properties of the Portuguese version of the Frost Multidimensional Perfectionism Scale. METHODS: Two hundred and seventeen (178 females) s [...] tudents from two Portuguese Universities filled in the scale, and a subgroup (n = 166) completed a retest with a four weeks interval. RESULTS: The scale reliability was good (Cronbach alpha = .857). Corrected item-total correlations ranged from .019 to .548. The scale test-retest reliability suggested a good temporal stability with a test-retest correlation of .765. A principal component analysis with Varimax rotation was performed and based on the Scree plot, two robust factorial structures were found (four and six factors). The principal component analyses, using Monte Carlo PCA for parallel analyses confirmed the six factor solution. The concurrent validity with Hewitt and Flett MPS was high, as well as the discriminant validity of positive and negative affect (Profile of Mood Stats-POMS). DISCUSSION: The two factorial structures (of four and six dimensions) of the Portuguese version of Frost Multidimensional Perfectionism Scale replicate the results from different authors, with different samples and cultures. This suggests this scale is a robust instrument to assess perfectionism, in several clinical and research settings as well as in transcultural studies.

Ana Paula Monteiro, Amaral; Maria João, Soares; Ana Telma, Pereira; Sandra Carvalho, Bos; Mariana, Marques; José, Valente; Vasco, Nogueira; Maria Helena, Azevedo; António, Macedo.

162

Modelling shallow landslide susceptibility by means of a subsurface flow path connectivity index and estimates of soil depth spatial distribution  

Directory of Open Access Journals (Sweden)

Full Text Available Topographic index-based hydrological models have gained wide use to describe the hydrological control on the triggering of rainfall-induced shallow landslides at the catchment scale. A common assumption in these models is that a spatially continuous water table occurs simultaneously across the catchment. However, during a rainfall event isolated patches of subsurface saturation form above an impeding layer and their hydrological connectivity is a necessary condition for lateral flow initiation at a point on the hillslope.

Here, a new hydrological model is presented, which allows us to account for the concept of hydrological connectivity while keeping the simplicity of the topographic index approach. A dynamic topographic index is used to describe the transient lateral flow that is established at a hillslope element when the rainfall amount exceeds a threshold value allowing for (a development of a perched water table above an impeding layer, and (b hydrological connectivity between the hillslope element and its own upslope contributing area. A spatially variable soil depth is the main control of hydrological connectivity in the model. The hydrological model is coupled with the infinite slope stability model and with a scaling model for the rainfall frequency–duration relationship to determine the return period of the critical rainfall needed to cause instability on three catchments located in the Italian Alps, where a survey of soil depth spatial distribution is available. The model is compared with a quasi-dynamic model in which the dynamic nature of the hydrological connectivity is neglected. The results show a better performance of the new model in predicting observed shallow landslides, implying that soil depth spatial variability and connectivity bear a significant control on shallow landsliding.

C. Lanni

2012-11-01

163

Modelling shallow landslide susceptibility by means of a subsurface flow path connectivity index and estimates of soil depth spatial distribution  

Science.gov (United States)

Topographic index-based hydrological models have gained wide use to describe the hydrological control on the triggering of rainfall-induced shallow landslides at the catchment scale. A common assumption in these models is that a spatially continuous water table occurs simultaneously across the catchment. However, during a rainfall event isolated patches of subsurface saturation form above an impeding layer and their hydrological connectivity is a necessary condition for lateral flow initiation at a point on the hillslope. Here, a new hydrological model is presented, which allows us to account for the concept of hydrological connectivity while keeping the simplicity of the topographic index approach. A dynamic topographic index is used to describe the transient lateral flow that is established at a hillslope element when the rainfall amount exceeds a threshold value allowing for (a) development of a perched water table above an impeding layer, and (b) hydrological connectivity between the hillslope element and its own upslope contributing area. A spatially variable soil depth is the main control of hydrological connectivity in the model. The hydrological model is coupled with the infinite slope stability model and with a scaling model for the rainfall frequency-duration relationship to determine the return period of the critical rainfall needed to cause instability on three catchments located in the Italian Alps, where a survey of soil depth spatial distribution is available. The model is compared with a quasi-dynamic model in which the dynamic nature of the hydrological connectivity is neglected. The results show a better performance of the new model in predicting observed shallow landslides, implying that soil depth spatial variability and connectivity bear a significant control on shallow landsliding.

Lanni, C.; Borga, M.; Rigon, R.; Tarolli, P.

2012-11-01

164

Experimental measurements of the effects of frost formation on heat exchanger performance  

International Nuclear Information System (INIS)

Frost formation on compact heat exchangers can lead to reductions in heat transfer of the order of 50 to 75% and to substantial increases in pressure drop. These effects are dependent upon the spatial pattern of the frost deposition, the growth history of the frost, and the thicknesses of the frost. This paper describes a series of experiments to measure the effects of frost when cold air (260 - 273 K) is passing through the exchanger. It is found that the thermal performance is a function of time and specific humidity levels while the pressure is function only of the frost thickness and surface roughness

165

FROST - FREEDOM OPERATIONS SIMULATION TEST VERSION 1.0  

Science.gov (United States)

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

166

Low frost-point humidity generator. [calibration facility  

Science.gov (United States)

A low frost-point humidity generator has been developed at NBS to provide a capability for calibration, testing, and research at very low levels of water vapor content in such gases as atmospheric air, carbon dioxide and nitrogen. The generator produces frost points from -30 to -100 C at ambient pressures from 500 to 200,000 pascals (0.005 to 2 atm.). This is equivalent to mixing ratios of 4 micrograms to 51 grams of water vapor per kilogram of dry air and to vapor pressures of .0014 to 38 pascals. The generated test gas can be fed to a test chamber with independent temperature control between +25 and -100 C. The uncertainty of the frost point in the test chamber is estimated not to exceed 0.05 deg C.

Greenspan, L.

1973-01-01

167

Frost sensor for use in defrost controls for refrigeration  

Science.gov (United States)

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

168

Statistical Examination of Frost Characterization: A Case of Global Warming Impact in Jordan  

Directory of Open Access Journals (Sweden)

Full Text Available Radiation and advection frost are common in Jordan as well as other neighboring countries as they face several frost waves each year during the late months of winter. Recently, many frost episodes hit the valley and damaged the crops that were compensated by millions of dollars by the Jordanian Government. This manuscript addresses and characterizes frost, and assesses the role of global warming in impacting frost in terms of its frequency, severity, and total number of frost days per year. A comprehensive statistical approach was used. The paper indicates that frost waves will continue to hit in the near future regardless of the fact that Earth is moving towards warmer conditions. Agricultural and financial authorities should be urged to minimize frost damage by considering installing wind fans in Jordan valley as an active method in addition to implementing good farm practices (as a passive methods where deemed necessary.

Moshrik R Hamdi

2011-08-01

169

Heat transfer from a tube immersed in a fluidized bed with frosting  

International Nuclear Information System (INIS)

Heat-transfer and flow-visualization experiments were performed for a single cooled tube immersed horizontally in a fluidized bed under frosting conditions. Measurements were made from local and average heat-transfer coefficients around the cooled tube surface. Glass beads having nominal diameters of 0.43 mm, 0.89 mm, and 1.6 mm were employed as the bed material. The 30 mm diameter tube was located 100 mm above the distributor. All the results obtained under frosting conditions were for an air temperature of about 5 degrees C and an air relative humidity of about 80 percent. The heat-transfer coefficient with frosting evaluated in this investigation includes the heat-transfer coefficient from the frost surface to the bed and the thermal resistance of the frost layer. Comparisons are made to heat-transfer data without frosting. The heat transfer is found to be larger with frosting than without frosting under the fluidization state

170

The control of carbon dioxide cryodeposits. [of frost for liquid hydrogen tankage thermal protection  

Science.gov (United States)

An experimental study has been conducted to investigate the parameters affecting the cryodeposition of carbon dioxide frost. In the investigation carbon dioxide frost was cryodeposited from a helium-carbon dioxide mixture into a layer of fibrous insulation surrounding a cylindrical cryogenic tank. Results of the study indicated that not only did deposition occur on the frost surface but also within the frost layer. Over the range of variables investigated both the frost density and the mass of frost deposited were most sensitive to the time of deposition, the percent of carbon dioxide in the purge-gas mixture, and the thickness of the insulation. Frost density and mass of frost deposition were found to increase with time and percent carbon dioxide, and to decrease with increasing insulation thickness.

Sharpe, E. L.

1973-01-01

171

Correlation of Water Frost Porosity in Laminar Flow over Flat Surfaces  

Science.gov (United States)

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

172

Quantitative trait loci of frost tolerance and physiologically related trait in faba bean (Vicia faba L.)  

OpenAIRE

In faba bean, field based winter-hardiness is a complex trait that is significantly correlated to frost tolerance. Frost tolerance could be used to indirectly select for faba bean winter-hardiness. The aim of this study was to identify putative QTL associated with frost tolerance and auxiliary traits and to quantify the efficiency of marker assisted selection. Thus, 101 recombinant inbred lines derived from the cross between two frost tolerant lines were tested for their hardened and unharden...

Arbaoui, Mustapha; Link, Wolfgang; Satovic, Zlatko; Torres, Ana-maria

2008-01-01

173

Predicting Frost Resistance of Concrete with Different Coarse Aggregate Concentration by Porosity Parameters  

OpenAIRE

Frost resistance is one of the key indicators of concrete quality. Frost resistance can be determined by direct testing; however it is time-consuming and labour-intensive method. Concrete decomposition is a complex process (from initial signs of degradation to complete failure of the surface subjected to freezing) involving many factors. Frost resistance of concrete can be predicted from porosity parameters after determining their relation to frost resistance. Test results showed the relation...

Nagrockiene?, Dz?igita; Skripkiu?nas, Gintautas; Girskas, Giedrius

2011-01-01

174

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

OpenAIRE

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 surfa...

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

2013-01-01

175

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

OpenAIRE

• 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.

Mccully, M. E.; Canny, M. J.; Huang, C. X.

2004-01-01

176

Annual variations of frost table in Kangerlussuaq Airport, western Greenland  

DEFF Research Database (Denmark)

Ground-penetrating radar (GPR) has been used to study the annual variations of the frost table beneath the southern parking area at Kangerlussuaq Airport, western Greenland. In autumn 2000, three test areas were painted white in order to reduce further development of depressions in the asphalt pavement initiated by permafrost degradation. One of these white painted areas has been used in the investigations to compare the annual variations of the frost table underneath a normal black asphalt surface to with that below a more reflective surface. The investigations were carried out from July 2005 until August 2006. The GPR measurements have shown a clear correlation between the use of the reflective surface and a reduced depth in the annual variations to the frost table. In late summer (August) the difference in the depths to the frost table is almost 20 ns, which corresponds to approximately 0.9 m. This constitutes a major difference in the thermal conditions below the reflective surface and the normal black asphalt surface.

JØrgensen, Anders Stuhr; Ingeman-Nielsen, Thomas

2007-01-01

177

Genetic architecture of winter hardiness and frost tolerance in triticale.  

Science.gov (United States)

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

178

Condensation phenomena and frost problems in the air heat recuperators  

Directory of Open Access Journals (Sweden)

Full Text Available Investigation results of condensation phenomena and frost problems in the ventilation heat recuperators are presented. The experiments have been conducted for typical value of indoor temperature 20°C and a large range of humidity values from 20 to 75% and more of an exhausted air. The heat exchanger worked in the real conditions of the winter climate in Bialystok.

Adamski Mariusz

2014-01-01

179

Features of frost-affected areas from digital METEOSAT IR images  

Science.gov (United States)

Frost is a natural hazard, which may cause significant damage to agriculture depending also on the phenological stage of the affected crops. In this paper, several features of the frost-affected areas are examined by using digital data of METEOSAT IR images. In particular the areal extent of frost is delineated by using the estimated temperature from the raw satellite data. Moreover, since digital METEOSAT IR images are recorded every thirty (30) minutes, it is possible to monitor the changes in the size of the frost-affected areas as well as the fluctuations in frost intensity and severity. The phenomenon is investigated in several regions in Greece.

Dalezios, N. R.; Lavrediadou, E. E.

180

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  

Energy Technology Data Exchange (ETDEWEB)

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

181

Frost behavior of a fin surface with temperature variation along heat exchanger fins  

International Nuclear Information System (INIS)

This paper presents a mathematical model for predicting the frost behavior formed on heat exchanger fins, considering fin heat conduction under frosting condition. The model is composed of air-side, the frost layer, and fin region, and they are coupled to the frost layer. The frost behavior is more accurately predicted with fin heat conduction considered (Case A) than with a constant fin surface temperature assumed (Case B). The results indicate that the frost thickness and heat transfer rate for Case B are over-predicted in most regions of the fin, as compared to those for Case A. Also, for Case A, the maximum frost thickness varies little with the fin length variations, and the extension of the fin length over 30 mm contributes insignificantly to heat transfer

182

Efectos genéticos de la formación de calosa en ápices radicales de líneas de maíz resistentes y susceptibles a suelos ácidos / Genetic effects in callose content in root apex of inbred resistant and susceptible corn lines to acid soils  

Scientific Electronic Library Online (English)

Full Text Available SciELO Colombia | Language: Spanish Abstract in spanish El objetivo de este trabajo fue estudiar la herencia de la producción de calosa utilizando líneas endogámicas de maíz. Seleccionando 14 líneas (7 tolerantes y 7 susceptibles a suelos ácidos) se formó un dialelo que fue probado en campo y en invernadero. Se determinó el contenido de calosa en los 91 [...] cruzamientos resultantes y los 14 progenitores. Para ello se colocaron las semillas en cámara de crecimiento en condiciones controladas. Después de 4-5 días las plántulas fueron transferidas a cubetas que contenían solución nutritiva con aireación constante. Luego de 48 horas se adicionaron 25 µM de aluminio (AlCl3) a cada una de las cubetas y se mantuvieron por 12 horas. Se cortaron tres ápices radicales de cada genotipo y se mantuvieron en etanol 96%. Para medir el contenido de calosa se utilizó Methyl blue como colorante, este forma un complejo con la calosa llamado Siruflúor-calosa, que es medido con el espectrofotómetro de fluorescencia. Se encontraron diferencias significativas para los progenitores, los cruzamientos y los progenitores Vs cruzamientos. El contenido de calosa de los progenitores varió de 0.746 a 2.035 µg PE/cm ápice de raíz. La heterosis varió desde -21.2% a 276.3%. La Habilidad Combinatoria General (HCG) y la Habilidad Combinatoria Específica (HCE) fueron altamente significativas, lo que indica que tanto los efectos genéticos aditivos y no aditivos fueron importantes en la herencia de calosa. El 46% de SC entre cruzamientos correspondió a la HCG y el 54% a la HCE. El coeficiente de correlación entre el contenido de calosa y la producción de grano del maíz en el campo fue negativo aunque no significativo (r = -0.38). Abstract in english The main objective of this work was to identify genetic parameters that are related to callose accumulation using tropical inbreeds corn. Fourteen inbreed lines selected for different levels of tolerance to acid soils were chosen and a diallel among them was generated. The seeds were grown under con [...] trolled environmental conditions in a growth chamber and transferred to a nutrient solution at pH 4.3. After 12 hours of 25 µM Al (AlCl3) treatment was applied, callose contents of 1 cm root apex were determined with fluorescence spectrophotometer. Significant differences were found for parents, crosses and parents vs crosses. Average callose content varied from 0.746 to 2.035 (µg PE/cm root apex). Heterosis varied from -21.2% to 276.3%. General combining ability (GCA) and specific combining ability (SCA) were highly significant indicating that both, additive and non-additive gene effects were important for callose inheritance. SCA and GCA sum of squares accounted for 54% and 46%, respectively of crosses of squares sum. Correlation coefficient between callose content and corn grain yield in the field was negative but not significant (r = -0.38).

Alba Lucía, Arcos; Luis Alberto, Narro; Fredy, Salazar; Creuci, Caetano.

183

Soils  

International Nuclear Information System (INIS)

For Austria there exists a comprehensive soil data collection, integrated in a GIS (geographical information system). The content values of pollutants (cadmium, mercury, lead, copper, mercury, radio-cesium) are given in geographical charts and in tables by regions and by type of soil (forests, agriculture, greenland, others) for the whole area of Austria. Erosion effects are studied for the Austrian region. Legal regulations and measures for an effective soil protection, reduction of soil degradation and sustainable development in Austria and the European Union are discussed. (a.n.)

184

Assessment of the chloride migration coefficient, internal frost resistance, salt frost scaling and sulphate resistance of self-compacting concrete : with some interrelated properties  

OpenAIRE

This report describes laboratory and analytical studies of the chloride migration coefficient, D, defined by Tang, the salt frost scaling, the internal frost resistance and the sulphate resistance of SCC that contains increased amount of filler, different types of casting and different air content.

Persson, Bertil

2001-01-01

185

Estimativa da susceptibilidade à compactação e do suporte de carga do solo com base em propriedades físicas de solos do Rio Grande do Sul Estimating soil susceptibility to compaction and load support capacity based on physical parameters of soils from Rio Grande do Sul State  

Directory of Open Access Journals (Sweden)

Full Text Available O conhecimento das relações entre propriedades físicas e mecânicas do solo pode contribuir no desenvolvimento de funções de pedotransferência, que permitam estimar outras propriedades do solo de difícil mensuração. Neste trabalho, objetivou-se avaliar a relação entre a susceptibilidade à compactação e o suporte de carga com propriedades físicas de solos do sul do Brasil. Foram avaliadas a resistência à penetração, a umidade, a densidade e a compressibilidade de seis solos. A resistência à penetração pode ser estimada pelo modelo que considera a umidade e densidade do solo. Solos com maior densidade inicial apresentaram menor susceptibilidade à compactação e menor deformação, quando submetidos a pressões externas. Quanto maior a resistência do solo à penetração, menor é a deformação e maior é a capacidade de suporte de carga, embora isso não indique solos com qualidade física adequada para as culturas; quanto maior a deformação do solo, maior a susceptibilidade à compactação e menor a capacidade de suporte de carga. A susceptibilidade de um solo à compactação e sua capacidade de suporte de carga podem ser estimadas, respectivamente, pela densidade inicial e pela resistência do solo à penetração.Quantifying the relationship between physical and mechanical soil properties can contribute to the development of pedotransfer functions that allow estimating hard-to-measure soil properties. The objective of this study was to evaluate the interrelations between susceptibility to compaction and load support with some physical properties of soils from Southern Brazil. Penetration resistance, moisture, bulk density and compressibility of six soils were evaluated. In a model including soil moisture and bulk density as independent variables, the relation with penetration resistance values obtained in the field was high. Soils with higher initial bulk density were less susceptible to compaction and exhibited less deformation under external loads. With increasing soil penetration resistance, less deformation and greater load support were observed, which does not necessarily indicate a satisfactory soil physical quality for crop cultivation. The greater the soil deformation, the higher is the susceptibility to compaction and the lower is its load support. The compaction susceptibility and load support of a soil can be estimated, respectively, by its initial bulk density and resistance to penetration.

Luis Eduardo Akiyoshi Sanches Suzuki

2008-06-01

186

Estimativa da susceptibilidade à compactação e do suporte de carga do solo com base em propriedades físicas de solos do Rio Grande do Sul / Estimating soil susceptibility to compaction and load support capacity based on physical parameters of soils from Rio Grande do Sul State  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese O conhecimento das relações entre propriedades físicas e mecânicas do solo pode contribuir no desenvolvimento de funções de pedotransferência, que permitam estimar outras propriedades do solo de difícil mensuração. Neste trabalho, objetivou-se avaliar a relação entre a susceptibilidade à compactação [...] e o suporte de carga com propriedades físicas de solos do sul do Brasil. Foram avaliadas a resistência à penetração, a umidade, a densidade e a compressibilidade de seis solos. A resistência à penetração pode ser estimada pelo modelo que considera a umidade e densidade do solo. Solos com maior densidade inicial apresentaram menor susceptibilidade à compactação e menor deformação, quando submetidos a pressões externas. Quanto maior a resistência do solo à penetração, menor é a deformação e maior é a capacidade de suporte de carga, embora isso não indique solos com qualidade física adequada para as culturas; quanto maior a deformação do solo, maior a susceptibilidade à compactação e menor a capacidade de suporte de carga. A susceptibilidade de um solo à compactação e sua capacidade de suporte de carga podem ser estimadas, respectivamente, pela densidade inicial e pela resistência do solo à penetração. Abstract in english Quantifying the relationship between physical and mechanical soil properties can contribute to the development of pedotransfer functions that allow estimating hard-to-measure soil properties. The objective of this study was to evaluate the interrelations between susceptibility to compaction and load [...] support with some physical properties of soils from Southern Brazil. Penetration resistance, moisture, bulk density and compressibility of six soils were evaluated. In a model including soil moisture and bulk density as independent variables, the relation with penetration resistance values obtained in the field was high. Soils with higher initial bulk density were less susceptible to compaction and exhibited less deformation under external loads. With increasing soil penetration resistance, less deformation and greater load support were observed, which does not necessarily indicate a satisfactory soil physical quality for crop cultivation. The greater the soil deformation, the higher is the susceptibility to compaction and the lower is its load support. The compaction susceptibility and load support of a soil can be estimated, respectively, by its initial bulk density and resistance to penetration.

Luis Eduardo Akiyoshi Sanches, Suzuki; Dalvan José, Reinert; José Miguel, Reichert; Cláudia Liane Rodrigues de, Lima.

2008-06-01

187

Portrayal of Realism and Rationalism in the Selected Poems of Robert Frost  

Directory of Open Access Journals (Sweden)

Full Text Available Robert Frost (1874-1963 is a famous American Poet. As most of his poems are autobiographical in subject, it is evident that he has been mostly influenced by the environment around him in composing his masterpieces. Frost’s themes are very simple in the surface meaning endowed with an easily understandable diction and a liberal style of writing. Yet, a careful study of his works vividly reveals his greatness as a ‘true’ judge of various critical aspects associated with the everyday experiences of the humans. His major characters- the narrators in “Stopping by Woods on a Snowy Evening”, “Mending wall” and “The Road not Taken” are viewed as the real people with real struggles in real life. It is seen that Frost’s poetry is highly connotative and the same reader can interpret the poetry of Robert Frost in multiple ways in multiple settings. The present article aims at critically examining Frost’s ‘realistic’ and ‘rationalistic’ approaches in the elevation of human nature under the broad spectrum of human life. This article also aims at proving that no poem of Frost ends in an absolute imagination because Frost himself seems to believe in realism as the ultimate fate of the individuals though fancy and imagination provides a temporary relief to the disturbed soul.

Sathi Veerraghava Reddy

2014-06-01

188

Plant resistance to cold stress: mechanisms and environmental signals triggering frost hardening and dehardening.  

Science.gov (United States)

This introductory overview shows that cold, in particular frost, stresses a plant in manifold ways and that the plant's response, being injurious or adaptive, must be considered a syndrome rather than a single reaction. In the course of the year perennial plants of the temperate climate zones undergo frost hardening in autumn and dehardening in spring. Using Scots pine (Pinus sylvestris L.) as a model plant the environmental signals inducing frost hardening and dehardening, respectively, were investigated. Over 2 years the changes in frost resistance of Scots pine needles were recorded together with the annual courses of day-length and ambient temperature. Both act as environmental signals for frost hardening and dehardening. Climate chamber experiments showed that short day-length as a signal triggering frost hardening could be replaced by irradiation with far red light, while red light inhibited hardening. The involvement of phytochrome as a signal receptor could be corroborated by respective night-break experiments. More rapid frost hardening than by short day or far red treatment was achieved by applying a short period (6 h) of mild frost which did not exceed the plant's cold resistance. Both types of signals were independently effective but the rates of frost hardening were not additive. The maximal rate of hardening was - 0.93 degrees C per day and frost tolerance of less than < - 72 degrees C was achieved. For dehardening, temperature was an even more effective signal than day-length. PMID:15625401

Beck, Erwin H; Heim, Richard; Hansen, Jens

2004-12-01

189

FROST: an ASIC for digital mammography with synchrotron radiation  

International Nuclear Information System (INIS)

The FRONTier RADiography (FRONTRAD) collaboration is developing a digital system for mammography at the Elettra Synchrotron Light Source in Trieste. The system is based on a silicon microstrip detector array. The ASIC FROST (FRONTRAD Read Out sySTem) was developed as a collaboration between INFN Trieste and Aurelia Microelettronica and is designed to operate in single photon counting mode. FROST provides low-noise and high-gain performances and is able to work at incident photon rates higher than 100 kHz with almost 100% efficiency. The ASIC has been tested and the first images of mammographic test objects will be shown. The acquisition time per breast image should be of about 10 s

190

Climate Change Shifts Frost Seasons and Plant Growth  

Science.gov (United States)

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.

191

Morning Frost in Trench Dug by Phoenix, Sol 113  

Science.gov (United States)

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

192

A new model for predicting performance of fin-and-tube heat exchanger under frost condition  

International Nuclear Information System (INIS)

Accurate prediction of frost characteristics has crucial influence on designing effective heat exchangers. In this paper, a new CFD (Computational Fluid Dynamics) model has been proposed to predict the frost behaviour. The initial period of frost formation can be predicted and the influence of surface structure can be considered. The numerical simulations have been carried out to investigate the performance of fin-and-tube heat exchanger under frost condition. The results have been validated by comparison of simulations with the data computed by empirical formulas. The transient local frost formation has been obtained. The average frost thickness, heat exchanger coefficient and pressure drop on air side has been analysed as well. In addition, the influence factors have also been discussed, such as fin pitch, relative humidity, air flow rate and evaporating temperature of refrigerant.

193

Frost flowers in the laboratory: growth, characteristics, aerosol, and the underlying sea ice  

OpenAIRE

In the laboratory, we have investigated the growth and composition of frost flowers. Their ionic composition has shown little difference from those of field measurements. Young frost flowers grown on sea ice are saline, leading us to speculate that wicking occurs continually during their growth on sea ice. The surface area of frost flowers is only a little larger than the area of ice underneath, consistent with recent field measurements from the Arctic. Time-lapse photography has allowed us t...

Roscoe, Howard K.; Brooks, B.; Jackson, A. V.; Smith, M. H.; Walker, S. J.; Obbard, Rachel W.; Wolff, Eric W.

2011-01-01

194

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

OpenAIRE

I describe a simple heat-engine derivation of the maximum overburden pressure that can 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 an idealized frost heave engine, together with the maximum thermodynamic efficiency of any heat engine, one can derive the maximum overburden pressure. A similar argument can also pro...

Libbrecht, Kenneth G.

2008-01-01

195

Late spring and early autumn frosts in connection with global warming.  

Czech Academy of Sciences Publication Activity Database

Nitra : Slovak Agricultural University, 2011 - (Šiška, B.; Hauptvogl, M.; Eliašová, M.), s. 1-5 ISBN 978-80-552-0640-0. [Bioclimate - source and limit of social development. International scientific conference. Topol?ianky (SK), 06.09.2011-09.09.2011] Institutional research plan: CEZ:AV0Z30120515 Keywords : global warming * global temperature * frost-free period * last spring frost * first autumn frost Subject RIV: DE - Earth Magnetism, Geodesy, Geography

St?eštík, Jaroslav

196

Frosting and defrosting of air-coils - results from laboratory testing  

Energy Technology Data Exchange (ETDEWEB)

Frosting of air-coils is an important factor in the design and operation of air-source heat pumps, heat recovery ventilators, cooling and refrigeration equipment etc. This report presents results from laboratory testing of two brine-cooled air-coils under frosting conditions. The coils have the same number of plane, continuous fins, 4 tube rows with 12 tubes in each row, tube spacing of 50 mm and fin spacing of 3 and 6 mm respectively. The original purpose of the test program was to compare various possible indicators of coil frosting and to analyze the possible effects of different control strategies on coil capacity and the COP of the system (the analysis will be presented in a separate report). Tests involved inlet air temperatures of -7 and +2 degC, variation of humidity between 70 and 100% RH (including simulated rain), velocities in the range 1 to 4 m/s, and specific cooling loads from 50 to 150 W/m{sup 2}. Test results include variations due to frosting of e.g. cooling capacity, COP, air flow and pressure drop, fan power, air outlet temperature and humidity, coil temperature, frost mass, and frosting time. Results also include the subsequently required defrost time, defrost energy and collected mass of defrost water. The frosting process was interrupted when the air flow had decreased to 30% of the original value with a non-frosted coil. The results clearly show the advantage of demand controlled defrosting with variations in frosting time between 2 h with high humidity/high specific cooling load up to, for practical purposes, infinite frosting times with low humidity/low specific cooling load. The accumulated frost mass during one frosting cycle varied from less than 0.02 kg/m{sup 2} up to approximately 0.4 kg/m{sup 2}. 23 refs, 93 figs, 89 tabs

Fahlen, P.

1996-12-31

197

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

OpenAIRE

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 ...

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

2014-01-01

198

Differential acclimation capacity to frost in sugarcane varieties grown under field conditions  

OpenAIRE

In certain sugarcane (Saccharum spp. hybrids) production regions of the world, including South Africa, frost frequently occurs. Great demand exists for frost tolerant sugarcane varieties as production in these areas could become more profitable. Two Louisiana (USA) varieties, known to yield high sugar even when immature (LCP 85-384 and HOCP 96-540), and two South African varieties (N21 and N36) were evaluated in a field trial for frost tolerance. O-J-I-P chlorophyll a fluoresce...

Heerden, Philippus D. R.

2014-01-01

199

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

Science.gov (United States)

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 Frosted elfin density was inversely related to tree cover and declined when the density of wild indigo was 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

200

Fall frost resistance in willows used for biomass production. I. Characterization of seasonal and genetic variation.  

Science.gov (United States)

Fast-growing willow clones (six clones of Salix viminalis L. and one clone each of S. viminalis x S. schwerenii E. Wolf and S. dasyclados Wimm.) were compared with respect to growth rhythm and frost hardening in the fall. Frost resistance of stem tissues was assessed by controlled freezing followed by analysis of chlorophyll fluorescence and scoring of visible cambial discoloration. The fluorescence method proved superior to scoring based on visible cambial discoloration because it was more rapid and less subjective, but needed calibration against cambial damage. Frost hardening in mature parts of stems did not start until growth cessation was initiated in the shoot apices, irrespective of whether growth cessation occurred early or late in the fall. Frost resistance varied because of clonal variations in: (1) pre-hardening frost resistance; (2) timing of growth cessation and hence start of frost hardening; and (3) rate of frost hardening. Compared with coastal and southern clones, continental and northern clones started hardening earlier, and a continental clone proceeded through hardening more rapidly at a given temperature. A cross between a continental and coastal clone was intermediate in timing. The pre-hardening frost resistance, however, was unrelated to both growth and frost hardening characteristics. PMID:12651314

Ogren, Erling

1999-09-01

201

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

Science.gov (United States)

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

202

Early spring, severe frost events, and drought induce rapid carbon loss in high elevation meadows.  

Science.gov (United States)

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

203

Evaluation of the blackberry germplasm (Rubus spp. frost resistance at the Research Institute for Fruit Growing Pitesti  

Directory of Open Access Journals (Sweden)

Full Text Available The study concerns the evaluation of damage caused by strong frosts in the winter 2009-2010 to the blackberry plants in the experimental field of the RIFG Pitesti-M ? r ? cineni. There were taken under study 42 blackberry genotypes of the Institute collection, 11 selections originated from 6 hybrid combinations made in 2000 and 350 hybrids resulted from the 15 hybrid combinations, made in 2002. The objective of the work was to evaluate and identify genotypes with genetic resistance to negative temperatures extremely severe (-24.4 ? C in air and -25.5°C on snow surface knowing that the threshold resistance of the thornfree blackberry is the minimum temperature -14° .. -15°C and of the thorny ones -17°.. -18°C. The goal was to introduce the most resistant genotypes as basic genitors in the breeding program for the improving the frost resistance of the varieties and to promote them in culture. The evaluation was done on the stems, buds and shoots of plants in the bud-break and growth of fruiting shoots phenophases. It was found that the most varieties, selections and hybrids with semierect and erect habit were strongly damaged, with some exceptions that will be presented below, while the least affected were those with creeping habit and stems bent to the ground soil. Of all the genotypes Wilson Early variety, selections ARK 613 and ARK 609, 2 / 21 and hybrids : N x A-T 12, H -N1, H T4-R3, N x H-2/11 ? i N x H 2/T 13 were found to have high degree resistance to the extremely frosts of the 2009-2010 winter.

Gheorghe Mladin

2010-01-01

204

Frost resistance of concrete with crushed brick as aggregate  

Directory of Open Access Journals (Sweden)

Full Text Available The investigation included concrete made by using recycled brick as aggregate. Experimental work included several types of concrete made with the same cement content (385 kg/m3, and same consistency (slump about 1 cm. Recycled brick and combination of natural river aggregate and recycled brick were used as aggregates. The influence of percentage and grain size of crushed brick aggregate on concrete compressive strength, water absorption and frost resistance were observed. On the basis of the results obtained during experimental research, a general conclusion can be drawn that the application of recycled concrete as aggregate can lead to new composites with satisfactory physical-mechanical properties.

Jankovi? Ksenija

2010-01-01

205

An Albedo Map and Frost Model of Pluto.  

Science.gov (United States)

The once-per-century set of occultations of Pluto by its satellite Charon enable the construction of an albedo map of Pluto's sub-Charon hemisphere, which in turn provides a basis for models of volatile transport on Pluto. Photometric observations of the Pluto-Charon mutual events were obtained at the University of Texas McDonald Observatory from 1985 through 1990. We use three least squares models to find the surface albedo distributions that best match the observed lightcurves. All of the least squares fits use a singular value decomposition (SVD) implementation. The three models produce similar albedo maps. Features of the maps include a large, very bright region over the south pole, a dark band over the mid-southern latitudes, a bright band over the mid-northern latitudes. The average normal reflectance of the higher northern latitudes is about the same as Pluto's global average of 0.5. We do not find compelling evidence of a bright cap over the north polar region. We model Pluto's atmosphere and albedo for the period from 1990 to 2040. Pluto's surface temperature drops by about six degrees during this period, resulting in over 97% of its current atmosphere condensing onto the surface. As Pluto's atmosphere thins, the winds arising from sublimation-driven pressure gradients increase beyond Mach 1. Our model predicts that the crossover to supersonic winds occurs around 2070. Our current frost migration model is valid only for the subsonic regime, but a supersonic frost transport model may help to explain the polar asymmetry of Pluto's albedo distribution. In the short term, the bulk of the new frost is deposited on the south pole. The change in albedo distribution is sensitive to the manner in which new frost reflectances are modeled, but the sheer volume of material (over 40 g/cm^2) deposited mandates the formation a bright cap on the south pole. The north pole may develop a smaller polar cap during this period. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617-253-5668; Fax 617-253-1690.).

Young, Eliot Fisher

1993-01-01

206

Genetic Architecture of Winter Hardiness and Frost Tolerance in Triticale  

OpenAIRE

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 fros...

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

2014-01-01

207

Simulating transmission and control of Taenia solium infections using a reed-frost stochastic model  

DEFF Research Database (Denmark)

The transmission dynamics of the human-pig zoonotic cestode Taenia solium are explored with both deterministic and stochastic versions of a modified Reed-Frost model. This model, originally developed for microparasitic infections (i.e. bacteria, viruses and protozoa), assumes that random contacts occur between hosts and that hosts can be either susceptible, infected or ‘recovered and presumed immune'. Transmission between humans and pigs is modelled as susceptible roaming pigs scavenging on human faeces infected with T. solium eggs. Transmission from pigs to humans is modelled as susceptible humans eating under-cooked pork meat harbouring T. solium metacestodes. Deterministic models of each scenario were first run, followed by stochastic versions of the models to assess the likelihood of infection elimination in the small population modelled. The effects of three groups of interventions were investigated using the model: (i) interventions affecting the transmission parameters such as use of latrines, meat inspection, and cooking habits; (ii) routine interventions including rapid detection and treatment of human carriers or pig vaccination; and (iii) treatment interventions of either humans or pigs. It is concluded that mass-treatment can result in a short term dramatic reduction in prevalence, whereas interventions targeting interruption of the life cycle lead to long-term reduction in prevalence.

Kyvsgaard, Niels Chr.; Johansen, Maria Vang

2007-01-01

208

Relationships among Vernalization, Shoot Apex Development and Frost Tolerance in Wheat  

OpenAIRE

• Background and Aims Frost tolerance of wheat depends primarily upon a strong vernalization requirement, delaying the transition to the reproductive phase. The aim of the present study was to learn how saturation of the vernalization requirement and apical development stage are related to frost tolerance in wheat.

Pra?s?il, Ilja Tom; Pra?s?ilova?, Pavla; Pa?nkova?, Kater?ina

2004-01-01

209

Infra-red thermography for detecting frost pockets on snow-covered clear-fellings  

International Nuclear Information System (INIS)

The purpose of the investigation was to find out if IR-thermography from aircraft could be a useful method for registration and studies of regional variation of frost exposition within an area and of distribution of frost risks within individual felling areas. The technique, which was successful, has up till now not been utilized in Sweden for such studies in woodland

210

Past and future changes in frost day indices on Catskill Mountains region of New York  

Science.gov (United States)

Changes in frost indices in New York's Catskill Mountains region, the location of water supply reservoirs for New York City, have potentially important implications. Frost day is defined as a day with Tmin < 0 deg C. The objective of this study was to investigate past and predicted changes in minimu...

211

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

International Nuclear Information System (INIS)

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

212

Frost as a first wall for the ICF Laboratory Microfusion Facility  

International Nuclear Information System (INIS)

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/cm3 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

213

Frost flower influence on springtime boundary-layer ozone depletion events and atmospheric bromine levels  

Science.gov (United States)

Springtime boundary layer ozone depletion events have been observed in both the Arctic and Antarctic. It has been suggested that these bromine-catalyzed depletion events may be caused by bromine released from frost flowers. We have measured the pH and ion concentrations of snow and frost flowers in the Ross Island, Antarctica area and find that if these are representative, frost flowers are unlikely to be a direct source of atmospheric bromine. The pH of the sampled frost flowers is too alkaline to support the release of molecular bromine resulting from the heterogeneous reaction of HOBr with Br ions. It is more likely that frost flowers are a source of aerosol bromine from which gas-phase bromine can be released through subsequent reactions in aerosol form or on the snow pack.

Kalnajs, Lars E.; Avallone, Linnea M.

2006-05-01

214

Evaluación de la susceptibilidad a la compactación en cuatro series de suelo bajo uso agrícola en Venezuela / Evaluation of the compaction susceptibility in four series of soil under agricultural use in Venezuela  

Scientific Electronic Library Online (English)

Full Text Available SciELO Venezuela | Language: Spanish Abstract in spanish La compactación de suelos es uno de los procesos de degradación física más común en suelos agrícolas altamente productivos y una de las causas de la reducción de la productividad. Bajo esta perspectiva, se justifica el desarrollo de metodologías que permitan estimar los riesgos de compactación de lo [...] s suelos, para así prevenir o mitigar sus efectos adversos. En el presente estudio se construyeron las curvas de compactación de suelos representativos de cuatro series bajo uso agrícola en Venezuela: Valle Lindo y Valle de Quíbor (Lara), Turén (Portuguesa) y El Patillal (Falcón), utilizando la metodología del Proctor estándar, con el propósito de estimar el grado de susceptibilidad de los suelos a compactarse, estimando los contenidos de humedad en los cuales presentan mayores riesgos de compactación. Asimismo, se estimaron las relaciones de las variables de la curva de compactación, humedad crítica y densidad aparente máxima, con las propiedades del suelo, distribución de tamaño de partículas y materia orgánica, y se encontró que mayores contenidos de partículas gruesas y bajos contenidos de materia orgánica originaron mayores niveles de densidad a menores contenidos de humedad, mientras que el predominio de partículas finas y altos contenidos de materia orgánica produjeron menores niveles de densidad a mayores contenidos de humedad. Los suelos FL de la serie Quíbor presentaron mayor susceptibilidad a la compactación que los suelos de similar granulometría de la serie Turén. Por otra parte, los suelos arenosos de la serie El Patillal presentaron mayor susceptibilidad que los suelos del mismo grupo textural de Quíbor y Valle Lindo. Abstract in english Soil compaction is one of the most common physic degradation processes in highly productive agricultural lands and one of the reasons of productivity reduction. In this situation it is justified the development of methodologies that allows estimating the soil compaction risk, and so, prevent or miti [...] gate its adverse effects. In this study, the compaction representative curves of the soil series Valle Lindo and Valle de Quíbor (Lara State), Turén (Portuguesa State), and El Patillal (Falcón State), Venezuela, were developed, using the standard Proctor methodology, with the purpose of using it as a tool to estimate the susceptibility degree of the soil to get compaction, estimating the humidity contents in which the soil present greatest risks of compaction. There were also estimated the relationship of the variables of the compaction curve (critic moisture and maximum bulk density) with the soil properties (particles size distribution and organic matter) and it was found that greatest contents of thick particles and low organic matter content originated largest densities at lowest humidity contents, while the prevalence of fine particles and high organic matter content produced lower densities at higher humidity content. The FL soils of Quíbor presented greater susceptibility to compaction that soils with similar texture of Turén. On the other hand, the sandy soils of the El Patillal presented greater risks of compaction than the soils of same textural group of Quíbor and Valle Lindo.

Willians J, Reyes R.

2010-04-01

215

Evaluación de la susceptibilidad a la compactación en cuatro series de suelo bajo uso agrícola en Venezuela Evaluation of the compaction susceptibility in four series of soil under agricultural use in Venezuela  

Directory of Open Access Journals (Sweden)

Full Text Available La compactación de suelos es uno de los procesos de degradación física más común en suelos agrícolas altamente productivos y una de las causas de la reducción de la productividad. Bajo esta perspectiva, se justifica el desarrollo de metodologías que permitan estimar los riesgos de compactación de los suelos, para así prevenir o mitigar sus efectos adversos. En el presente estudio se construyeron las curvas de compactación de suelos representativos de cuatro series bajo uso agrícola en Venezuela: Valle Lindo y Valle de Quíbor (Lara, Turén (Portuguesa y El Patillal (Falcón, utilizando la metodología del Proctor estándar, con el propósito de estimar el grado de susceptibilidad de los suelos a compactarse, estimando los contenidos de humedad en los cuales presentan mayores riesgos de compactación. Asimismo, se estimaron las relaciones de las variables de la curva de compactación, humedad crítica y densidad aparente máxima, con las propiedades del suelo, distribución de tamaño de partículas y materia orgánica, y se encontró que mayores contenidos de partículas gruesas y bajos contenidos de materia orgánica originaron mayores niveles de densidad a menores contenidos de humedad, mientras que el predominio de partículas finas y altos contenidos de materia orgánica produjeron menores niveles de densidad a mayores contenidos de humedad. Los suelos FL de la serie Quíbor presentaron mayor susceptibilidad a la compactación que los suelos de similar granulometría de la serie Turén. Por otra parte, los suelos arenosos de la serie El Patillal presentaron mayor susceptibilidad que los suelos del mismo grupo textural de Quíbor y Valle Lindo.Soil compaction is one of the most common physic degradation processes in highly productive agricultural lands and one of the reasons of productivity reduction. In this situation it is justified the development of methodologies that allows estimating the soil compaction risk, and so, prevent or mitigate its adverse effects. In this study, the compaction representative curves of the soil series Valle Lindo and Valle de Quíbor (Lara State, Turén (Portuguesa State, and El Patillal (Falcón State, Venezuela, were developed, using the standard Proctor methodology, with the purpose of using it as a tool to estimate the susceptibility degree of the soil to get compaction, estimating the humidity contents in which the soil present greatest risks of compaction. There were also estimated the relationship of the variables of the compaction curve (critic moisture and maximum bulk density with the soil properties (particles size distribution and organic matter and it was found that greatest contents of thick particles and low organic matter content originated largest densities at lowest humidity contents, while the prevalence of fine particles and high organic matter content produced lower densities at higher humidity content. The FL soils of Quíbor presented greater susceptibility to compaction that soils with similar texture of Turén. On the other hand, the sandy soils of the El Patillal presented greater risks of compaction than the soils of same textural group of Quíbor and Valle Lindo.

Willians J Reyes R

2010-04-01

216

Evaluation and improvement of frost durability of clay bricks  

Science.gov (United States)

In cold regions like Canada, frost action was reported to be the major cause of disintegration of brick veneer. Two approaches to ensure frost durability of clay bricks were studied in this research. One involved the evaluation of durability, while the other studied the improvement of durability through impregnation. In order to carry out these studies, three major objectives were set out for this research. They were: (1) to develop an index to evaluate frost durability, (2) to investigate the feasibility of using nondestructive methods to evaluate durability, and (3) to study the effect of impregnation with different materials on improving durability. It was intended in this research to develop a general durability index for clay bricks, irrespective of the manufacturing process adopted. The performance of the brick was studied using laboratory freeze-thaw test. As the time and facility requirements necessary for the unidirectional freezing test were beyond the constraints which existed in this research, an accelerated omnidirectional freeze-thaw test was used. This fact must be considered while interpreting the results from the freeze-thaw test. The study carried out to compare the performance of existing durability indices showed that they had limitations in reliably assessing durability. Therefore new durability indices were developed based on water absorption properties of bricks. These indices were found to overcome the limitations of existing indices. The feasibility study on nondestructive evaluation of durability was carried out using ultrasonic pulse velocity. New durability provisions were derived based on pulse velocity, using ASTM C216 specifications. At this stage it can be used only along with the ASTM method but it can avoid the time consuming ASTM procedure in many cases. Studies on impregnated bricks showed that there was a general shifting of pore sizes towards lower diameter region. Paraffin impregnated brick showed excellent freeze-thaw performance. The bond between brick and mortar was found to have been adversely affected due to impregnation. But more studies using brick wall component are recommended before final conclusions are drawn on brick-mortar bond strength. Paraffin was found to be the most cost effective among the impregnating materials studied.

Koroth, Surej Raghavan

217

Modeling the airside dynamic behavior of a heat exchanger under frosting conditions  

International Nuclear Information System (INIS)

A general distributed model with a non-steady-state heat exchanger model coupled with a frost model was developed to study the dynamic behavior of an airside heat exchanger in an air-to-water heat pump heater/chiller unit. The effects of water vapor diffusion and uneven fin temperature distribution were considered. The model was found to agree well with reported experimental results. Compared with the routine model, the present model has higher precision of frost layer thickness especially on the fin surface. Results include the propagation of frost formation along the tube and its effect on the dynamic characteristics of refrigerant, air, and tube sides. According to the results, the temperature difference between air and tube surface temperature was proposed to be the main driving force of frosting. Tube surface temperature is the most important factor affecting frosting when there is little variation in air humidity. Frost at the fin base was found to be thicker than that at the fin tip due to the fact that the frost layer grows faster with lower tube surface temperature

218

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

International Nuclear Information System (INIS)

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.

219

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

Energy Technology Data Exchange (ETDEWEB)

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

220

CFD analysis of tube-fin 'no-frost' evaporators  

Directory of Open Access Journals (Sweden)

Full Text Available The purpose of this paper is to assess some aspects of the design of evaporators for household refrigeration appliances using Computational Fluid Dynamics (CFD. The evaporators under study are tube-fin 'no-frost' heat exchangers with forced convection on the air-side and a staggered tube configuration. The calculation methodology was verified against experimental data for the heat transfer rate, thermal conductance and pressure drop obtained for two evaporators with different geometries. The average errors of the heat transfer rate, thermal conductance and pressure drop were 10%, 3% and 11%, respectively. The CFD model was then used to assess the influence of geometric parameters such as the presence and position of the electrical heater coil relative to the tubes, the fin configuration and the width of the by-pass clearance between the outer edge of the fins and the tube bank for conditions typical of the design of household refrigeration appliances

Jader R Barbosa, Jr

2010-12-01

221

Mechanisms of salt frost scaling on portland cement-bound materials: studies and hypothesis  

OpenAIRE

A hypothesis regarding the mechanism causing salt frost scaling on Portland cement-bound materials is described. It is assumed that deterioration is due to osmotic micro ice body growth, as has been previously proposed for frost deterioration of moisture-isolated specimens of cement-bound materials. In moisture-isolated specimens, this ice body growth stops when the micro structure is drained to a certain extent. In a specimen ex-posed to salt frost attack, however, an outer liquid phase will...

Lindmark, Sture

1998-01-01

222

The minimum temperatures in the winter 2006/07 in Slovenian frost hollows and cold basins  

Directory of Open Access Journals (Sweden)

Full Text Available The members of Slovenian Meteorological Forum, Department of Geography at University of Ljubljana and Slovenian Forestry Institute started to measure temperatures in Slovenian frost hollows and cold basins in 2004. The measurements, which improved during the period 2004.2006, continued also in the winter 2006.2007, all together, in more than 30 frost hollows and cold basins Alpine, Dinaridic and even Submediterranean areas. Although the winter 2006/2007 was very mild, minimum temperatures in frost hollow Hribarice fell below -35°C.

Matej Ogrin

2007-12-01

223

Portrayal of Realism and Rationalism in the Selected Poems of Robert Frost  

OpenAIRE

Robert Frost (1874-1963) is a famous American Poet. As most of his poems are autobiographical in subject, it is evident that he has been mostly influenced by the environment around him in composing his masterpieces. Frost’s themes are very simple in the surface meaning endowed with an easily understandable diction and a liberal style of writing. Yet, a careful study of his works vividly reveals his greatness as a ‘true’ judge of various critical aspects associated with the everyday expe...

Sathi Veerraghava Reddy

2014-01-01

224

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

Science.gov (United States)

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

225

Magnetic susceptibility in the prediction of soil attributes in two sugarcane harvesting management systems / Suscetibilidade magnética na predição de atributos do solo em dois sistemas de manejo na colheita de cana de açúcar  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese O presente trabalho teve como objetivo investigar o potencial de uso da suscetibilidade magnética (SM) como componente da função de pedotransferência para predição de atributos do solo, sob dois sistemas de manejo na colheita de cana-de-açúcar. Para cada uma das duas áreas de 1 ha (uma com colheita [...] mecanizada de cana crua e outra com colheita manual de cana queimada), foram coletadas 126 amostras de solo que foram submetidas às análises de laboratório, para determinação dos atributos físicos, químicos e mineralógicos do solo e para medição da SM. Os dados foram submetidos à estatística descritiva, calculando-se a média e o coeficiente de variação. Para comparar as médias nos diferentes sistemas de manejo, foi realizado o teste de Tukey, ao nível de significância de 5%. Foram realizados o teste de correlação simples para averiguar a correlação da SM com outros atributos do solo e a regressão múltipla linear a fim de avaliar o quanto a SM contribui para a predição de atributos complexos do solo. Os resultados demonstram que a SM apresentou, em ambos os sistemas de manejo de colheita da cana-de-açúcar, correlação estatística com atributos químicos, físicos e mineralógicos do solo e apresentou potencial para ser utilizada como componente da função de pedotransferência para predição de atributos do Latossolo estudado. Abstract in english This study aimed to investigate the potential use of magnetic susceptibility (MS) as pedotransfer function to predict soil attributes under two sugarcane harvesting management systems. For each area of 1 ha (one with green sugarcane mechanized harvesting and other one with burnt sugarcane manual har [...] vesting), 126 soil samples were collected and subjected to laboratory analysis to determine soil physical, chemical and mineralogical attributes and for measuring of MS. Data were submitted to descriptive statistics by calculating the mean and coefficient of variation. In order to compare the means in the different harvesting management systems it was carried out the Tukey test at a significance level of 5%. In order to investigate the correlation of the MS with other soil properties it was made the correlation test and aiming to assess how the MS contributes to the prediction of soil complex attributes it was made the multiple linear regressions. The results demonstrate that MS showed, in both sugarcane harvesting management systems, statistical correlation with chemical, physical and mineralogical soil attributes and it also showed potential to be used as pedotransfer function to predict attributes of the studied oxisol.

Rafael G., Peluco; José, Marques Júnior; Diego S., Siqueira; Lucas A., Cortez; Gener T., Pereira.

1134-11-01

226

Varietal and chromosome 2H locus-specific frost tolerance in reproductive tissues of barley (Hordeum vulgare L.) detected using a frost simulation chamber.  

Science.gov (United States)

Exposure of flowering cereal crops to frost can cause sterility and grain damage, resulting in significant losses. However, efforts to breed for improved low temperature tolerance in reproductive tissues (LTR tolerance) has been hampered by the variable nature of natural frost events and the confounding effects of heading time on frost-induced damage in these tissues. Here, we establish conditions for detection of LTR tolerance in barley under reproducible simulated frost conditions in a custom-built frost chamber. An ice nucleator spray was used to minimize potential effects arising from variation in naturally occurring extrinsic nucleation factors. Barley genotypes differing in their field tolerance could be distinguished. Additionally, an LTR tolerance quantitative trait locus (QTL) on the long arm of barley chromosome 2H could be detected in segregating families. In a recombinant family, the QTL was shown to be separable from the effects of the nearby flowering time locus Flt-2L. At a minimum temperature of -3.5 degrees C for 2 h, detection of the LTR tolerance locus was dependent on the presence of the nucleator spray, suggesting that the tolerance relates to freezing rather than chilling, and that it is not the result of plant-encoded variation in ice-nucleating properties of the tiller surface. PMID:19484216

Chen, Andrew; Gusta, Lawrence V; Brûlé-Babel, Anita; Leach, Richard; Baumann, Ute; Fincher, Geoffrey B; Collins, Nicholas C

2009-08-01

227

Winter climate controls soil carbon dynamics during summer in boreal forests  

International Nuclear Information System (INIS)

Boreal forests, characterized by distinct winter seasons, store a large proportion of the global terrestrial carbon (C) pool. We studied summer soil C-dynamics in a boreal forest in northern Sweden using a seven-year experimental manipulation of soil frost. We found that winter soil climate conditions play a major role in controlling the dissolution/mineralization of soil organic-C in the following summer season. Intensified soil frost led to significantly higher concentrations of dissolved organic carbon (DOC). Intensified soil frost also led to higher rates of basal heterotrophic CO2 production in surface soil samples. However, frost-induced decline in the in situ soil CO2 concentrations in summer suggests a substantial decline in root and/or plant associated rhizosphere CO2 production, which overrides the effects of increased heterotrophic CO2 production. Thus, colder winter soils, as a result of reduced snow cover, can substantially alter C-dynamics in boreal forests by reducing summer soil CO2 efflux, and increasing DOC losses. (letter)

228

Temperature controls on sediment production in the Oregon Coast Range - abiotic frost-cracking processes vs. biotic-dominated processes over the last 40 ka  

Science.gov (United States)

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

229

CO_2 Frost Halos on the South Polar Residual Cap of Mars  

Science.gov (United States)

We present observational analysis, and a numerical model to explain the formation of bright CO_2 frost halos seen by HiRISE on the edges of scarps and "swiss cheese" features in the south polar residual cap of Mars.

Becerra, P.; Byrne, S.; HiRISE Team

2012-03-01

230

Siim Nestor soovitab : Ben Frost ja Alexander Robotnik Eclectical / Siim Nestor  

Index Scriptorium Estoniae

Austraalia muusik ja helilooja Ben Frost projektiga "6 guitars" esinemas festivali Eclectica raames 6. sept. Tartu klubis Rock ja Roll ja itaalia diskor Alexander Robotnik 7. sept. klubis Trehv, esinejatest

Nestor, Siim, 1974-

2007-01-01

231

Electoral Susceptibility  

CERN Document Server

In the United States electoral system, a candidate is elected indirectly by winning a majority of electoral votes cast by individual states, the election usually being decided by the votes cast by a small number of "swing states" where the two candidates historically have roughly equal probabilities of winning. The effective value of a swing state in deciding the election is determined not only by the number of its electoral votes but by the frequency of its appearance in the set of winning partitions of the electoral college. Since the electoral vote values of swing states are not identical, the presence or absence of a state in a winning partition is generally correlated with the frequency of appearance of other states and, hence, their effective values. We quantify the effective value of states by an {\\sl electoral susceptibility}, $\\chi_j$, the variation of the winning probability with the "cost" of changing the probability of winning state $j$. We study $\\chi_j$ for realistic data accumulated for the 201...

Levine, G C; Cerise, J E

2012-01-01

232

Moisture design with regard to deterioration of materials and structures - with special reference to frost destruction  

OpenAIRE

The work is composed of three parts: - (1) An overview of the concept moisture deign with regard to service life. (this report) - (2) A practical application of service life analysis applied to frost damage, based on materials testing. (this report) - (3) A theroretical analysis of methods for service life design of concrete and concrete structures exposed to internal frost damage (Report TVBM-04/3119).

Fagerlund, Go?ran

2006-01-01

233

David Sanders. A Divided Poet: Robert Frost, North of Boston, and the Drama of Disappearance.  

OpenAIRE

David Sanders in his monograph entitled A Divided Poet: Robert Frost, North of Boston, and the Drama of Disappearance (2011) sheds light on the dilemmas, doubts and personal conflicts Frost confronted while composing his poetic collection North of Boston in which some of his most well-known lyrics, such as “Mending Wall,” “After Apple-Picking,” and “The Wood-Pile,” are contained. This book should be considered alongside a number of other publications either in monograph or essay f...

Rapatzikou, Tatiani G.

2012-01-01

234

Metal stress consequences on frost hardiness of plants at northern high latitudes: a review and hypothesis  

International Nuclear Information System (INIS)

This paper reviews the potential of trace/heavy metal-induced stress to reduce plant frost hardiness at northern high latitudes. The scientific questions are first outlined prior to a brief summary of heavy metal tolerance. The concepts of plant capacity and survival adaptation were used to formulate a hypothesis, according to which heavy metal stress may reduce plant frost hardiness for the following reasons: (1) Heavy metals change membrane properties through impaired resource acquisition and subsequent diminution of the cryoprotectant pool. (2) Heavy metals change membrane properties directly through oxidative stress, i.e. an increase of active oxygen species. (3) The involved co-stress may further increase oxidative stress. (4) The risk of frost injury increases due to membrane alterations. An opposite perspective was also discussed: could metal stress result in enhanced plant frost hardiness? This phenomenon could be based on the metabolism (i.e. glutathione, polyamines, proline, heat shock proteins) underlying a possible general adaptation syndrome of stress (GAS). As a result of the review it was suggested that metal-induced stress seems to reduce rather than increase plant frost hardiness. - Metal stress may reduce plant frost hardiness

235

CFD analysis of tube-fin 'no-frost' evaporators  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english The purpose of this paper is to assess some aspects of the design of evaporators for household refrigeration appliances using Computational Fluid Dynamics (CFD). The evaporators under study are tube-fin 'no-frost' heat exchangers with forced convection on the air-side and a staggered tube configurat [...] ion. The calculation methodology was verified against experimental data for the heat transfer rate, thermal conductance and pressure drop obtained for two evaporators with different geometries. The average errors of the heat transfer rate, thermal conductance and pressure drop were 10%, 3% and 11%, respectively. The CFD model was then used to assess the influence of geometric parameters such as the presence and position of the electrical heater coil relative to the tubes, the fin configuration and the width of the by-pass clearance between the outer edge of the fins and the tube bank for conditions typical of the design of household refrigeration appliances

Jader R, Barbosa, Jr; Christian J. L, Hermes; Cláudio, Melo.

2010-12-01

236

Formation of Frost Layer of Water Ice on Mars  

Science.gov (United States)

Formation of the frost layer on Mars' surface in the pictures taken by the Viking 2 Lander is discussed on the basis of the observation of hoar crystals on the snow surface at the Dome Fuji station in the inland area of the Antarctic Ice Sheet on the Earth. The growth rate of a hoar crystal by condensation of water vapor was estimated from the experimental results on artificial production of ice crystals in a cold box and the equation on whisker growth as 10 -5 cm s -1 at 210 K at the Viking 2 Lander site. If this estimation can be extended to the Mars North Ice Cap region at 180 K, the total mass of hoar crystals formed during 100 Mars days in winter can be estimated to be 0.1-1 mm water cm -2. Since these values are of the same order as annual evaporation rates calculated by the modeling, it can be concluded that direct condensation of water ice on the surface will contribute to accumulation at the Mars North Ice Cap.

Higuchi, Keiji

2001-11-01

237

Erodibilidade e suscetibilidade à erosão dos solos de cerrado com plantio de Acacia mangium em Roraima.= Erodibility and susceptibility to erosion of the savannah (cerrado soils planted with Acacia mangium in the State of Roraima.  

Directory of Open Access Journals (Sweden)

Full Text Available Com o objetivo de avaliar erodibilidade e suscetibilidade à erosão de solos sob cerrados e plantios de Acácia mangium no estado de Roraima, foram realizadas visitas nas áreas objeto de estudo para identifi cação geomorfopedológica e feito coleta de solo representativo de 121 perfi s distribuídos nas áreas de plantio de Acacia mangium pertencentes ao projeto Ouro Verde Agrosilvopastoril Ltda. Os perfi s descritos e coletados foram georreferenciados através de GPS e plotados sobre mapas de declividades no software ARCMAPE 8.0 permitindo cruzar os valores de R com a declividade. Foi avaliada as relações do tipo de solo, sua posição na paisagem e suscetibilidade a erosão. Os resultados revelaram que as áreas de estudo estão inseridas em duas unidades geomorfopedológicas distintas: Jacitara/Mucajaí/Santa Cecília (JMSta e Serra da Lua (SL, apresentando suscetibilidade à erosão bem contrastantes; As unidades JMSta apresentam maiores valores de R, inseridas em relevo plano, com declividade entre 1% a 3%, os solos da unidade SL, apresentam menores valores de R e estão posicionados em relevo com declividade entre 3 a 13%, o que a torna mais vulneráveis a erosão; as classes de solos em ordem decrescente em valores de R são: Neossolos (RQo, Argissolos (PAd, Gleissolos (GXbd, Latossolos (LAd, LVd, LVAd, LVA Plintico, Plintossolos (FFCd, concluindo-se então, a necessidade da adoção de práticas simples de conservação de solos, tais como plantio em curva de nível e até terraceamento. = With the objective to evaluate the erodibility and susceptibility to erosion of the cerrado and plantations with Acacia mangium in the State of Roraima, visits to the areas were done for geomorfopedologic identifi cation and collection of soils representative of 121 profi les distributed in the areas pertaining to the plantation of Acacia mangium of the Ouro Verde Agrosilvopastoril Ltda project. The described and collected profiles were geo-referenced through GPS and located on maps of declivities by the software ARCMAPE 8,0 allowing to cross the values of R with the declivity. There were evaluate the relations of the type of soils, its position in the landscape and susceptibility the erosion. The results obtained indicated that the areas studiedy are inserted in two distinct geomorphopedologic units: Jacitara/Mucajai/Santa Cecilia (JMSta and Serra da Lua (SL, and demonstrated distinct susceptibility to erosion; The JMSta units presented the most elevated values of R, inserted in plain relief, with declivity between 1% and 3%. The ground of unit SL, presented small values of R and is located in terrain with declivity between 3% and 13%, which becomes it more vulnerable to erosion; The types of soils decreasing order of values of R are: Neossolos (RQo, Argissolos (PAd, Gleissolos (GXbd, Latossolos (LAd, LVd, LVAd, LVA Plintico, Plintossolos (FFCd. In conclusion, there is the necessity to adopt simple practices of ground conservation, varying from plantation on the curve of level to terracing.

José Frutuoso do Vale Júnior

2009-07-01

238

The effects of design and operating factors on the frost growth and thermal performance of a flat plate fin-tube heat exchanger under the frosting condition  

International Nuclear Information System (INIS)

An experimental study of the effects of various factors(fin pitch, fin arrangement, air temperature, air humidity, and air velocity) on the frost growth and thermal performance of a fin-tube heat exchanger has been conducted under the frosting condition. It is found that the thermal performance of a heat exchanger is closely related to the blockage ratio of the air flow passages due to the frost growth. The maximum allowable blockage ratio is used to determine the criteria for the optimal operating conditions of a fin-tube heat exchanger. It is also shown that heat transfer rate of heat exchanger with staggered fin arrangement increases about 17% and the time required for heat transfer rate to reach a maximum value becomes longer, compared with those of an inline fin-tube heat exchanger under the frosting condition. The energy transfer resistance between the air and coolant decreases with the increase of inlet air temperature and velocity and with decreasing inlet air humidity

239

Experimental study on condensation, frost formation and condensate retention on microgrooved and plain brass surfaces under natural convection condition  

OpenAIRE

In this study, frost was grown on microgrooved and baseline brass samples under specific operating conditions and a comparison of condensation, frosting and defrosting pattern on microgrooved and flat brass surfaces were carried out experimentally. The surfaces were fabricated by mechanical micro-machining process and no chemical alteration of the surface was conducted. It was found that the shape, size and distribution of condensed water droplets and subsequent frost ...

Rahman, Ma; Jacobi, Am

2011-01-01

240

Susceptibility to shallow landslides of soil in the municipality of Temoaya, Mexico: multicriteria analysis / Susceptibilidad a deslizamientos superficiales de suelo en el Municipio de Temoaya, México: aplicación del análisis multicriterio  

Scientific Electronic Library Online (English)

Full Text Available Debido al carácter montañoso del espacio geográfico mexicano, así como del impacto ecológico generado por los cambios de uso de suelo, efectuados particularmente en las últimas décadas, y de la ocurrencia de fenómenos hidrometeorológicos de gran intensidad o frecuencia, la inestabilidad de laderas d [...] esencadenada por precipitación constituye uno de los peligros de mayor impacto en diversas regiones del país, entre ellas el municipio de Temoaya, Estado de México. En este municipio, donde el relieve montañoso formado por depósitos vulcanoclásticos poco consolidados y afallados favorece la inestabilidad, existen 33 procesos de remoción en masa activos, de los cuales treinta -los más importantes-, son deslizamientos de suelo superficiales de tipo traslacional (DSST), un deslizamiento de derrubios y dos caídas de rocas. La ocurrencia de los DSST está controlada por el carácter de los depósitos vulcanoclásticos, específicamente flujos piroclásticos de bloques, cenizas y pómez, los cuales al ser materiales permeables favorecen la infiltración, por lo que si el material subyacente es impermeable o de menor permeabilidad, se presenta una acumulación de agua sobre el contacto litológico subhorizontal que se transforma en un flujo que conduce a la inestabilidad del material sobreyacente. En este trabajo se presenta la aplicación del Método de Análisis Multicriterio para la generación de un mapa de susceptibilidad a deslizamientos de suelo superficiales de tipo traslacional para dicha zona. De acuerdo con el mapa elaborado, el 15% del territorio municipal presenta muy alta susceptibilidad a deslizamientos, mientras que la zona de alta susceptibilidad ocupa el 35% del área en cuestión. El nivel de susceptibilidad medio se concentra en el 30% del territorio, y en el restante 20% de la zona de interés, la susceptibilidad a deslizamientos es baja y muy baja. Abstract in english Owing to the mountainous character of the Mexican terrain, as well as the ecological effects of changes in land use, particularly in recent decades, and the occurrence of severe and frequent hydro-meteorological phenomena, the instability of slopes dislodged by precipitation constitutes a major haza [...] rd in various regions of the country, among them the municipality of Temoaya in the State of Mexico. In this municipality, where the mountainous relief formed by poorly consolidated and faulting volcaniclastic deposits favours instability, there are 33 active processes of mass movement, of which thirty -the most important- are shallow soil translational landslides (SSTL), one is a debris slide and two are rock falls. The occurrence of SSTLs is controlled by the character of the volcaniclastic deposits, specifically pyroclastic flows of blocks, ash and pumice; because these are permeable materials they favour infiltration; if the subjacent material is impermeable or of low permeability, water accumulates on the sub-horizontal lithological contact and transforms into a flow that leads to the instability of the overlying material. A map of susceptibility to SSTLs was generated by means of a multicriteria analysis. According to the map produced, 15% of the municipality is very highly susceptible to landslides, 35% is highly susceptible, 30% shows medium susceptibility, and the remaining 20% has low or very low susceptibility.

Patricia, Flores; Irasema, Alcántara Ayala.

2012-04-01

241

Increasing frost risk associated with advanced citrus flowering dates in Kerman and Shiraz, Iran: 1960-2010  

Science.gov (United States)

Flowering dates and the timing of late season frost are both driven by local ambient temperatures. However, under climatic warming observed over the past century, it remains uncertain how such impacts affect frost risk associated with plant phenophase shifts. Any increase in frost frequency or severity has the potential to damage flowers and their resultant yields and, in more extreme cases, the survival of the plant. An accurate assessment of the relationship between the timing of last frost events and phenological shifts associated with warmer climate is thus imperative. We investigate spring advances in citrus flowering dates (orange, tangerine, sweet lemon, sour lemon and sour orange) for Kerman and Shiraz, Iran from 1960 to 2010. These cities have experienced increases in both T max and T min, advances in peak flowering dates and changes in last frost dates over the study period. Based on daily instrumental climate records, the last frost dates for each year are compared with the peak flowering dates. For both cities, the rate of last frost advance lags behind the phenological advance, thus increasing frost risk. Increased frost risk will likely have considerable direct impacts on crop yields and on the associated capacity to adapt, given future climatic uncertainty.

Fitchett, Jennifer M.; Grab, Stefan W.; Thompson, Dave I.; Roshan, Gholamreza

2014-10-01

242

Current and emerging screening methods to identify post-head-emergence frost adaptation in wheat and barley.  

Science.gov (United States)

Cereal crops can suffer substantial damage if frosts occur at heading. Identification of post-head-emergence frost (PHEF) resistance in cereals poses a number of unique and difficult challenges. Many decades of research have failed to identify genotypes with PHEF resistance that could offer economically significant benefit to growers. Research and breeding gains have been limited by the available screening systems. Using traditional frost screening systems, genotypes that escape frost injury in trials due to spatial temperature differences and/or small differences in phenology can be misidentified as resistant. We believe that by improving techniques to minimize frost escapes, such 'false-positive' results can be confidently identified and eliminated. Artificial freezing chambers or manipulated natural frost treatments offer many potential advantages but are not yet at the stage where they can be reliably used for frost screening in breeding programmes. Here we describe the development of a novel photoperiod gradient method (PGM) that facilitates screening of genotypes of different phenology under natural field frosts at matched developmental stages. By identifying frost escapes and increasing the efficiency of field screening, the PGM ensures that research effort can be focused on finding genotypes with improved PHEF resistance. To maximize the likelihood of identifying PHEF resistance, we propose that the PGM form part of an integrated strategy to (i) source germplasm;(ii) facilitate high throughput screening; and (iii) permit detailed validation. PGM may also be useful in other studies where either a range of developmental stages and/or synchronized development are desired. PMID:22888127

Frederiks, T M; Christopher, J T; Harvey, G L; Sutherland, M W; Borrell, A K

2012-09-01

243

Structural Analysis of the Redesigned Ice/Frost Ramp Bracket  

Science.gov (United States)

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

244

The barley Frost resistance-H2 locus.  

Science.gov (United States)

Frost resistance-H2 (Fr-H2) is a major QTL affecting freezing tolerance in barley, yet its molecular basis is still not clearly understood. To gain a better insight into the structural characterization of the locus, a high-resolution linkage map developed from the Nure × Tremois cross was initially implemented to map 13 loci which divided the 0.602 cM total genetic distance into ten recombination segments. A PCR-based screening was then applied to identify positive bacterial artificial chromosome (BAC) clones from two genomic libraries of the reference genotype Morex. Twenty-six overlapping BACs from the integrated physical-genetic map were 454 sequenced. Reads assembled in contigs were subsequently ordered, aligned and manually curated in 42 scaffolds. In a total of 1.47 Mbp, 58 protein-coding sequences were identified, 33 of which classified according to similarity with sequences in public databases. As three complete barley C-repeat Binding Factors (HvCBF) genes were newly identified, the locus contained13 full-length HvCBFs, four Related to AP2 Triticeae (RAPT) genes, and at least five CBF pseudogenes. The final overall assembly of Fr-H2 includes more than 90 % of target region: all genes were identified along the locus, and a general survey of Repetitive Elements obtained. We believe that this gold-standard sequence for the Morex Fr-H2 will be a useful genomic tool for structural and evolutionary comparisons with Fr-H2 in winter-hardy cultivars along with Fr-2 of other Triticeae crops. PMID:24442711

Pasquariello, Marianna; Barabaschi, Delfina; Himmelbach, Axel; Steuernagel, Burkhard; Ariyadasa, Ruvini; Stein, Nils; Gandolfi, Francesco; Tenedini, Elena; Bernardis, Isabella; Tagliafico, Enrico; Pecchioni, Nicola; Francia, Enrico

2014-03-01

245

Mineralogia e susceptibilidade magnética dos óxidos de ferro do horizonte B de solos do Estado do Paraná / Mineralogy and magnetic susceptibility of iron oxides of B horizon of Paraná state soils  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Os solos tropicais altamente intemperizados tendem a acumular residualmente óxidos de ferro e alumínio. Entre os óxidos e hidróxidos de ferro presentes na fração argila, a goethita (Gt) e a hematita (Hm) são os mais abundantes e estudados. No entanto, há poucos estudos acerca da identificação e quan [...] tificação da maghemita (Mh), um mineral ferrimagnético que está na fração argila dos solos, principalmente naqueles desenvolvidos de rochas máficas. A Mh e a magnetita (Mt) são responsáveis pela magnetização espontânea dos solos. Esse atributo mineralógico pode ser medido nos solos e sedimentos pela susceptibilidade magnética por unidade de massa (?BF), cuja magnitude é proporcional à concentração dos minerais ferrimagnéticos e é objeto de estudos em todo mundo. O objetivo deste trabalho foi identificar e quantificar, por ?BF, os minerais ferrimagnéticos de 32 amostras do horizonte B de solos do Estado do Paraná. As formas minerais presentes na fração argila concentrada de óxidos de ferro foram identificadas e semiquantificadas por difratometria de raios-X (DRX). Nessa fração, os minerais mais abundantes são a Gt e a Hm. A Mh foi detectada em 31 amostras por ?BF e em apenas 17 por DRX. Os valores de ?BF variaram de 16 a 8.077 na TFSA, de 12 a 7.953 na fração argila e de 0 a 18.737x10-8 m³ kg-1 na fração argila, após concentração dos óxidos de ferro. A Mh dos solos estudados apresentou valor médio de ?BF em 62.728x10-8m³ kg-1 e sua presença nos difratogramas de raios-X só foi verificada em amostras com valores de ?BF acima de 1.000x10-8m³ kg-1. Abstract in english Highly weathered tropical soils tend to accumulate iron and aluminum oxy-hydroxides. Among the iron oxy-hydroxides found in the clay fraction, goethite (Gt) and hematite (Hm) are the most abundant and studied. A smaller number of investigations have been publish to identify and to quantify maghemite [...] (Mh), a ferrimagnetic mineral present in the clay size fraction of the soils, mainly in those developed from mafic rocks. Maghemite, along with magnetite (Mt) is responsible for the spontaneous magnetic behavior of the soils. This mineralogical attribute can be easy measured, in soils and sediments by mass magnetic susceptibility (?LF), which magnitude is proportional to the concentration of ferrimagnetic minerals and it has been object of studies worldwide. The purpose of this research was to identify and quantify, by ?LF, the ferrimagnetic minerals of 32 samples from B-horizons of Paraná state soils. The mineral species present in the iron oxides concentrated clay size fractions were identified and semiquantified by x-rays diffraction (XRD). In this fraction the most abundant minerals are Gt and Hm. Maghemite was detected in 31 samples by ?LF and in only 17 samples by XRD. The ?LF values ranged from 16 to 8.077x10-8m³ kg-1 in the fine earth; from 12 to 7.953x10-8m³ kg-1 in clay fraction and from 0 to 18.737x10-8m³ kg-1 in clay fraction, after concentration of the iron oxides. The Mh of the soils presented an average value of 62.728x10-8m³ kg-1 and their presence in the X-rays diffractograms was only observed in samples with ?LF values above 1.000x10-8m³ kg-1.

Ivan Granemann de, Souza Junior; Antonio Carlos Saraiva da, Costa; Cesar Crispim, Vilar; Allan, Hoepers.

2010-03-01

246

[Comparison of red edge parameters of winter wheat canopy under late frost stress].  

Science.gov (United States)

In the present study, late frost experiments were implemented under a range of subfreezing temperatures (-1 - -9 degrees C) by using a field movable climate chamber (FMCC) and a cold climate chamber, respectively. Based on the spectra of winter wheat canopy measured at noon on the first day after the frost experiments, red edge parameters REP, Dr, SDr, Dr(min), Dr/Dr(min) and Dr/SDr were extracted using maximum first derivative spectrum method (FD), linear four-point interpolation method (FPI), polynomial fitting method (POLY), inverted Gaussian fitting method (IG) and linear extrapolation technique (LE), respectively. The capacity of the red edge parameters to detect late frost stress was explicated from the aspects of the early, sensitivity and stability through correlation analysis, linear regression modeling and fluctuation analysis. The result indicates that except for REP calculated from FPI and IG method in Experiment 1, REP from the other methods was correlated with frost temperatures (P temperatures (P temperatures. The lower the temperature, the more obvious the trend is. Of all the REP, REP calculated by LE method had the highest correlation with frost temperatures which indicated that LE method is the best for REP extraction. In Experiment 1 and 2, only Dr(min) and Dr/Dr(min), calculated by FD method simultaneously achieved the requirements for the early (their correlations with frost temperatures showed a significant level P fluctuation coefficient is greater than 2.0) and stability (their correlations with frost temperatures al- ways keep a consistent direction). Dr/SDr calculated from FD and IG methods always had a low sensitivity in Experiment 2. In Experiment 1, the sensitivity of Dr/SDr from FD was moderate and IG was high. REP calculated from LE method had a lowest sensitivity in the two experiments. Totally, Dr(min) and Dr/Dr(min) calculated by FD method have the strongest detection capacity for frost temperature, which will be helpful to conducting the research on early diagnosis of late frost injury to winter wheat. PMID:25508739

Wu, Yong-feng; Hu, Xin; Lü, Guo-hua; Ren, De-chao; Jiang, Wei-guo; Song, Ji-qing

2014-08-01

247

Community impacts of mid-May frost event during an anomalously warm spring  

Science.gov (United States)

Global land and ocean surface temperatures of 2010 have gone on record as one of the warmest of the last 131 years. In the northeastern US extraordinarily warm spring temperatures were recorded, averaging +3 °C above the long term mean, causing very early leaf development. However, the entire northeastern US region was hit by a severe frost event. Leveraging the coincidence of an anomalously warm spring and a late spring frost event we assess species specific responses of these combined extremes for three northern hardwood species(sugar maple, American beech, yellow birch) across an elevational gradient. We integrated ground observations with satellite and near-surface remote sensing data to address the following questions: 1) How did different species respond to a gradient in altitude / freezing temperatures? 2) How does phenological strategy influence this response? 3) To what extent were regional effects measurable? 4) How did the late spring frost event alter the carbon balance of a northern hardwood forest? 5) Finally, what changes do we foresee in community ecology? Our results show an early onset for all species, triggered by the anomalously warm spring. However, the three species responded differently to a late spring frost event. Where both yellow birch and American beech remained largely unaffected by frost, by comparison, sugar maple showed severe frost damage with increasing altitude resulting in leaf loss and delayed canopy development. Conservative estimates of gross carbon exchange losses due to the frost event ranged from 63 g C m-2 to 156 g C m-2, or ~5% to ~13 % of the annual gross carbon exchange of a northern hardwood forest. Our results suggest that the additional pressure on forest succession at high altitude range margins due to late spring frost events may provide a competitive advantage for yellow birch and American beech, at the expense of sugar maple. Consequently, a late spring frost does not only affect the short term carbon balance but has the potential to alter forest composition, ecosystem function and long term biosphere-atmosphere interactions.

Hufkens, K.; Sonnentag, O.; Keenan, T. F.; Richardson, A. D.; Melaas, E. K.; Bailey, A.; O'Keefe, J.; Friedl, M. A.

2011-12-01

248

Seasonal polar carbon dioxide frost on Mars: CO2 mass and columnar thickness distribution  

Science.gov (United States)

Conclusions are drawn about the column density (g/cm2), spatial extent, and mass of the seasonal carbon dioxide frost on the poles of Mars as a function of time utilizing data from the 2001 Mars Odyssey Gamma Ray Spectrometer (GRS). Quantification of these CO2 values is achieved by observing attenuation effects of the surface-emitted hydrogen gamma ray flux as the frost condenses and sublimates in a seasonal exchange of CO2 between the ground and the atmosphere. 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 General Circulation Model and to similar experimental results from the Mars Odyssey High Energy Neutron Detector and Neutron Spectrometer. Models for north and south polar atmosphere and regolith distributions are incorporated, and our results indicate that the assumption of a 100% H2O-ice residual cap underlying the seasonal frost in the north is accurate. The GRS CO2 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 CO2 back into the atmosphere. The total amount of condensed carbon dioxide mass seen by the GRS is on the order of 6.0 × 1015 kg and verifies previous reports that nearly 25% of the Martian CO2 reservoir participates in the ground-atmosphere exchange cycle.

Kelly, N. J.; Boynton, W. V.; Kerry, K.; Hamara, D.; Janes, D.; Reedy, R. C.; Kim, K. J.; Haberle, R. M.

2006-12-01

249

Numerical analysis on the frosting performance of a fin-tube evaporator for a refrigerator  

International Nuclear Information System (INIS)

The objective of this study is to provide numerical and experimental data that can be used to investigate the performance characteristics of a flat plate fin-tube evaporator in household and commercial refrigerators under frosting conditions. Computer simulations with variations of operating conditions such as air inlet temperature, relative humidity, and geometries were performed to find out optimal design parameters of a fin-tube evaporator for household and commercial refrigerators. The tube-by-tube method was used in the simulation and the frost growth model was considered under frosting conditions. The developed analytical model predicted the decreasing rates of heat transfer capacity and air flow rate ratio within ± 10% compared to the experimental results for a refrigerator under real operating conditions. As a result, the frost thickness at 3 .deg. C and 80% is increased 40% than that of -3 .deg. C and 80%, and the frost thickness at 3 .deg. C and 90% is increased 30% than that of 3 .deg. C and 60%. Accordingly, the operating time of the evaporator in the refrigerator was reduced with the increase of the decreasing rate of air flow rate ratio at each condition

250

Short communication. Harvest time in hedgerow Arbequina olive orchards in areas with early frosts  

Energy Technology Data Exchange (ETDEWEB)

The shortening of harvest time attained in hedgerow olive (Olea europaea L.) orchards represents an advantage for the adoption of this cropping system in areas that are prone to suffer frost during the harvest period. To establish an optimal harvesting window, we carried out a study of the fruit ripening process on a hedgerow orchard of Arbequina olive trees, located in Zaragoza (Spain). From 2007 to 2009, oil accumulation on the fruit (% of dry weight) and oil yield (grams of oil per 100 fruits) were monitored, from early September to late November. Over the three years both variables peaked around November 15th, indicating that Arbequina reached full ripening earlier than has been reported previously for this variety. In two of the three seasons the orchard suffered several frosts during November. Long term climatic data from this area indicated that the risk of early frosts (< -2 degree centigrade) increases as November progresses with a high risk after November 20{sup t}h. In conclusion, the optimal harvesting period for Arbequina in this area should not extend beyond November 20{sup t}h. A rapid harvesting before this date is advisable to avoid the risk of damage caused by early frost in Zaragoza. Hedgerow planting provides an additional advantage in frost-prone areas, because mechanization of operations permits a short harvest period, easier to fit into the optimal harvesting window. (Author) 20 refs.

Gracia, P.; Sanchez-Gimeno, A. C.; Benito, M.; Oria, R.; Lasa, J. M.

2012-11-01

251

Micromechanics models and innovative sensor technologies to evaluate internal-frost damage of concrete  

Science.gov (United States)

Internal-frost damage is one of the major problems affecting the durability of concrete in cold regions. This paper presents micromechanics models and innovative sensor technologies to study the fundamental mechanisms of frost damage in concrete. The crystallization pressure due to ice nucleation with capillary pores is the primary cause of internal-frost damage of concrete. The crystallization pressure of a cylinder pore was formulated using interface energy balance with thermodynamics equations. The obtained crystallization pressure on the pore wall was input for the fracture simulation with the developed Extended Finite Element Model (XFEM). The XFEM fracture simulation on a homogeneous beam sample with a vertical cylinder pore leads to a straight line. The XFEM simulation was also conducted on the generated digital sample. The simulation results were favorable compared with the middle-notched single edge beam bending specimen due to the open-mode fracture behavior in both cases. An innovative Time-Domain Reflectometry (TDR) sensor was developed to nondestructively monitor the freezing process. The experimental data shows that the TDR sensor signals can detect the freezing degree, an important input parameter to micromechanics models. These studies indicate that the developed micromechanics models and TDR sensor techniques can be used by the practitioners to evaluate internal-frost damage of concrete. Future work will incorporate the TDR sensor measurements into micromechanics models to real-time predict the internal-frost damage process in concrete specimens. The predicted freeze-thaw damage process will be verified with acoustic emission detection.

Dai, Qingli; Yu, Xiong; Ng, Kenny; Zhou, Jun

2011-04-01

252

Evaluation of the impact of frost resistances on potential altitudinal limit of trees.  

Science.gov (United States)

Winter physiology of woody plants is a key issue in temperate biomes. Here, we investigated different frost resistance mechanisms on 1-year-old branches of 11 European tree species from November until budburst: (i) frost hardiness of living cells (by electrolyte leakage method), (ii) winter embolism sensitivity (by percentage loss of conductivity: PLC) and (iii) phenological variation of budburst (by thermal time to budburst). These ecophysiological traits were analyzed according to the potential altitudinal limit, which is highly related to frost exposure. Seasonal frost hardiness and PLC changes are relatively different across species. Maximal PLC observed in winter (PLCMax) was the factor most closely related to potential altitudinal limit. Moreover, PLCMax was related to the mean hydraulic diameter of vessels (indicating embolism sensitivity) and to osmotic compounds (indicating ability of living cells to refill xylem conducting elements). Winter embolism formation seems to be counterbalanced by active refilling from living cells. These results enabled us to model potential altitudinal limit according to three of the physiological/anatomical parameters studied. Monitoring different frost resistance strategies brings new insights to our understanding of the altitudinal limits of trees. PMID:24052567

Charrier, Guillaume; Cochard, Hervé; Améglio, Thierry

2013-09-01

253

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

Science.gov (United States)

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

254

Five second helium neutral beam injection using argon-frost cryopumping techniques  

International Nuclear Information System (INIS)

High power helium neutral beams for the heating of tokamak discharges can now be provided for 5 s by using argon cryopumping (of the helium gas) in the beamlines. A system has now been installed to deposit a layer of argon frost on the DIII-D neutral beam cryopanels, between tokamak injection pulses. The layer serves to trap helium on the cryopanels providing sufficient pumping speed for 5 s helium beam extraction. The argon frosting hardware is now present on two of four DIII-D neutral beamlines, allowing injection of up to 6 MW of helium neutral beams per discharge, with pulse lengths of up to 5 s. The argon frosting system is described, along with experimental results demonstrating its effectiveness as a method of economically extending the capabilities of cryogenic pumping panels to allow multi-second helium neutral beam injection

255

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

International Nuclear Information System (INIS)

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

256

Frost Growth CFD Model of an Integrated Active Desiccant Rooftop Unit  

Energy Technology Data Exchange (ETDEWEB)

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

257

Five second helium neutral beam injection using argon-frost cryopumping techniques  

Energy Technology Data Exchange (ETDEWEB)

High power helium neutral beams for the heating of tokamak discharges can now be provided for 5 s by using argon cryopumping (of the helium gas) in the beamlines. A system has now been installed to deposit a layer of argon frost on the DIII-D neutral beam cryopanels, between tokamak injection pulses. The layer serves to trap helium on the cryopanels providing sufficient pumping speed for 5 s helium beam extraction. The argon frosting hardware is now present on two of four DIII-D neutral beamlines, allowing injection of up to 6 MW of helium neutral beams per discharge, with pulse lengths of up to 5 s. The argon frosting system is described, along with experimental results demonstrating its effectiveness as a method of economically extending the capabilities of cryogenic pumping panels to allow multi-second helium neutral beam injection.

Phillips, J.C.; Kellman, D.H.; Hong, R.; Kim, J.; Laughon, G.M.

1995-10-01

258

Delineation of frost characteristics on cold walls by using a new formula for psychrometrics demarcation boundary  

International Nuclear Information System (INIS)

In this study, a direct formula that predicts either the frost formation on cold walls is correspondence to psychrometric-subsaturated or supersaturated regions is presented. The developed formula uses the data of the entering air dry-bulb temperature and absolute humidity, and the absolute humidity of the air at saturation corresponding to the coil surface temperature. Cases studies of demarcation criteria for frost formation on evaporator coil using experimental measured data, and on walls of cold storage freezer using measured data from literature are used to validate the formula and it is found that results are completely matches to the graphic plot of the data on the psychrometric chart. In case of cold storage freezers, the result clearly shows that a greater demarcation criteria value indicates frost formation under sever condition that is characterized as snow-like with low density and thermal conductivity.

259

Void structure of concrete with superabsorbent polymers and its relation to frost resistance of concrete  

DEFF Research Database (Denmark)

Superabsorbent polymers (SAP) can be used to control air void formation in concrete. However, due to surfactant left on suspension polymerized SAP particles during production, they may not only create SAP voids but also entrain extra air. In the present investigation, a method is tested to remove surfactant prior to concrete mixing. The method comprises rinsing of the SAP with ethanol. This effectively removes the surfactant. Freeze-thaw testing of concrete with rinsed and non-rinsed SAP shows that for equal dosages of SAP, the extra air entrained due to surfactant is considerable and can make the difference between poor and satisfactory frost-resistance. Furthermore, the results indicate that voids created directly by SAP protect concrete against frost deterioration just like other air voids; if the concrete contains enough SAP voids, these alone can provide sufficient frost resistance. © 2013 RILEM.

Hasholt, Marianne Tange; Jensen, Ole Mejlhede

2013-01-01

260

Environmental controls of frost cracking revealed through in situ acoustic emission measurements in steep bedrock  

Science.gov (United States)

Frost cracking, the breakdown of rock by freezing, is one of the most important mechanical weathering processes acting on Earth's surface. Insights on the mechanisms driving frost cracking stem mainly from laboratory and theoretical studies. Transferring insights from such studies to natural conditions, involving jointed bedrock and heterogeneous thermal and hydrological properties, is a major challenge. We address this problem with simultaneous in situ measurements of acoustic emissions, used as proxy of rock damage, and rock temperature/moisture content. The 1 year data set acquired in an Alpine rock wall shows that (1) liquid water content has an important impact on freezing-induced rock damage, (2) sustained freezing can yield much stronger damage than repeated freeze-thaw cycling, and (3) that frost cracking occurs over the full range of temperatures measured extending from 0 down to -15°C. These new measurements yield a slightly different picture than previous field studies where ice segregation appears to play an important role.

Girard, Lucas; Gruber, Stephan; Weber, Samuel; Beutel, Jan

2013-05-01

261

Moving Frost Hardy Genes From Wild to Cultivated Potatoes. Use of Precise Screening Tools to Make Real Progress  

Science.gov (United States)

The common cultivated species Solanum tubrosum is frost sensitive and is killed at temperatures below -2.5°C. It has been estimated that by increasing frost hardiness by 1–2 C one can expect an increase in potato yield by 26 to 40% in the Altiplano (Peru and Bolivia) covering 63,000 ha. of potatoes....

262

Heat transfer and frost growth on a wind convector based on a row of vertical cylindrical tubes  

Energy Technology Data Exchange (ETDEWEB)

A wind convector is an alternative outdoor heat exchanger for air-source heat pumps which allows transfer of heat from the outdoor environment to an antifreeze solution without the use of a fan to move the outdoor air across the heat exchange surfaces. A study was carried out to experimentally investigate the effects of weather conditions on the overall heat transfer coefficient for and frost growth on a wind convector based on a row of vertical cylindrical tubes placed outdoor, and to mathematically model the frost growth and heat transfer through the frost layer. An automatic microcomputer-monitored outdoor test facility capable of continuous measurement of overall wind convector heat transfer coefficient to within an uncertainty of {plus minus}3% was built and tested. Weather conditions measured include air temperature and humidity, wind speed and direction, solar radiation and rainfall. Frost depth is measured by a computer vision system and frost mass with a weighing cell. Mathematical models of the diffusion dominated and meltback regimes of frost growth were developed and compared to experimental heat transfer, frost mass and depth results for a frosting single cylinder in a steady wind tunnel environment, and the outdoor unsteady environment tube row. Compared to the experimental results the model underpredicts steady environment results by 13% (Reynold's number 2720) to 28% (Reynold's number 10,630) and calculates outdoor tube row results to within {plus minus}25%. 132 refs., 73 figs., 9 tabs.

Monaghan, P.F.

1988-12-01

263

Evaluations on power ramp data of PWR fuels by FROST and THERMOST codes  

International Nuclear Information System (INIS)

An evaluation is presented of power ramp data of Mitsubishi's PWR fuel rods tested in R-2, Studsvik, which was analysed by FROST and THERMOST codes. The analyses give good predictions for measured diameter changes and on-power rod elongations. The work indicates that FROST is capable of analysing both radial and axial pellet-cladding mechanism interaction (PCMI) appropriately, and that predicted states of PCMI (i.e. stress and strain which cannot be measured directly) are considered to be reliable. The ramp data used in the present analyses were obtained in two joint programmes with five Japanese PWR utilities (KEPCO, KYEPCO, SEPCO, HEPCO, and JAPCO). (UK)

264

Dynamics of frost resistance in various provenances of Abies grandis Lindl.  

OpenAIRE

The frost resistance of one year old needles and shoots of Abies grandis (seven provenances) and Abies alba (one provenance) was determined using Dexter's method since early autumn till late spring (September-May). Material was collected from trees over ten year old, planted in Beskid S?decki Range near Krynica, 800 m above sea level. In this study it was found, that in early autumn (September) A. grandis develops weaker frost hardiness than Abies alba. In the late autumn and in winter, prov...

Adam Dolnicki; Wojciech Kraj

1998-01-01

265

A nano-frost array technique to prepare nanoporous PVDF membranes  

Science.gov (United States)

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

266

TuBaFrost 5: multifunctional central database application for a European tumor bank.  

OpenAIRE

Developing a tissue bank database has become more than just logically arranging data in tables combined with a search engine. Current demand for high quality samples and data, and the ever-changing legal and ethical regulations mean that the application must reflect TuBaFrost rules and protocols for the collection, exchange and use of tissue. To ensure continuation and extension of the TuBaFrost European tissue bank, the custodianship of the samples, and hence the decision over whether to iss...

Isabelle, M.; Teodorovic, I.; Morente, Mm; Jamine?, D.; Passioukov, A.; Lejeune, S.; Therasse, P.; Dinjens, Wn; Oosterhuis, Jw; Lam, Kh; Oomen, Mh; Spatz, A.; Ratcliffe, C.; Knox, K.; Mager, R.

2006-01-01

267

Frost flower surface area and chemistry as a function of salinity and temperature  

OpenAIRE

Frost flowers play a role in air-ice exchange in polar regions, contribute to tropospheric halogen chemistry, and affect ice core interpretation. Frost flowers were observed and collected on the Hudson Bay in March 2008. Their specific surface area (SSA) was measured using CH4 adsorption at 77 K. The Brunauer-Emmett-Teller analysis produced SSA values between 63 and 299 cm(2) g(-1) (mean 162 cm(2) g(-1), accuracy and reproducibility 5%). This range is very similar to that of Domine et al. (20...

Obbard, Rachel W.; Roscoe, Howard K.; Wolff, Eric W.; Atkinson, Helen M.

2009-01-01

268

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

Science.gov (United States)

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

269

Induction of homologous low temperature and ABA-responsive genes in frost resistant (Solanum commersonii) and frost-sensitive (Solanum tuberosum cv. Bintje) potato species.  

Science.gov (United States)

A DNA fragment corresponding to a low-temperature- and ABA-responsive gene (Scdhn1) was amplified by PCR from genomic DNA of a wild, frost-resistant potato species, Solanum commersonii. A homologous gene (Stdhn1) was identified in Solanum tuberosum cv. Bintje, a frost-sensitive domesticated potato cultivar. The expression of the gene was studied during low temperature and ABA treatments in both Solanum species. The analysis revealed that both low temperature and ABA lead to the accumulation of a 1 kb transcript that corresponded to the PCR fragment. The induction of the gene was relatively rapid and maximum amounts of the transcripts were detected already after 1 day and 7 h of treatment with low temperature and ABA, respectively. Previous results have shown that there is no increase in the amount of endogenous ABA in S. tuberosum during low-temperature treatment, which indicates that two independent signalling pathways lead to the induction of this gene. PMID:8616256

Baudo, M M; Meza-Zepeda, L A; Palva, E T; Heino, P

1996-01-01

270

Effects of air flow maldistribution on refrigeration system dynamics of air source heat pump chiller under frosting conditions  

International Nuclear Information System (INIS)

The effects of air flow maldistribution on the performance of an air source heat pump chiller under frosting conditions were investigated experimentally. The results indicated that air flow maldistribution was the dominant factor leading to hunting of the thermostatic expansion valve for medium and/or large size finned tube evaporators. With air flow maldistribution degree (AMD) increasing, frost occurred earlier, and the frost layer grew faster. The operating characteristics became lower when AMD was increased. We found such phenomenon seemed to be related to both the difference of refrigerant outlet superheat and the frosting velocity. In the hunting stage, the frost block effect became the main factor degrading the refrigeration system performance. With AMD increasing, the heat pump system pertinent performance data (suction pressure, evaporation temperature, discharge pressure, refrigerant outlet temperature, etc.) were degraded more dramatically

271

Heat transfer and pressure drop amidst frost layer presence for the full geometry of fin-tube heat exchanger  

International Nuclear Information System (INIS)

The present study numerically solves the flow and thermal fields in the full geometry of heat exchanger modeling with frost layer presence on the heat exchanger surface. The effects of air inlet velocity, air inlet temperature, frost layer thickness, fin pitch, fin thickness, and heat exchanger shape on the thermo-hydraulic performance of a fin-tube heat exchanger are investigated. Heat transfer rate rises with increasing air inlet velocity and temperature, and decreasing frost layer thickness and fin pitch. Pressure drop rises with increasing air inlet velocity and frost layer thickness, and decreasing fin pitch. The effect of fin thickness on heat transfer and pressure drop is negligible. Based on the present results, we derived the correlations, which express pressure drop and temperature difference between air inlet and outlet as a function of air inlet velocity and temperature, as well as frost layer thickness

272

Effects of air flow maldistribution on refrigeration system dynamics of air source heat pump chiller under frosting conditions  

Energy Technology Data Exchange (ETDEWEB)

The effects of air flow maldistribution on the performance of an air source heat pump chiller under frosting conditions were investigated experimentally. The results indicated that air flow maldistribution was the dominant factor leading to hunting of the thermostatic expansion valve for medium and/or large size finned tube evaporators. With air flow maldistribution degree (AMD) increasing, frost occurred earlier, and the frost layer grew faster. The operating characteristics became lower when AMD was increased. We found such phenomenon seemed to be related to both the difference of refrigerant outlet superheat and the frosting velocity. In the hunting stage, the frost block effect became the main factor degrading the refrigeration system performance. With AMD increasing, the heat pump system pertinent performance data (suction pressure, evaporation temperature, discharge pressure, refrigerant outlet temperature, etc.) were degraded more dramatically.

Gong Jianying [Department of Refrigeration and Cryogenics, Xi' an Jiao Tong University, Xi' an 710049 (China)], E-mail: gong-jianying@163.com; Gao Tieyu; Yuan Xiuling; Huang Dong [Department of Refrigeration and Cryogenics, Xi' an Jiao Tong University, Xi' an 710049 (China)

2008-06-15

273

Effects of air flow maldistribution on refrigeration system dynamics of air source heat pump chiller under frosting conditions  

Energy Technology Data Exchange (ETDEWEB)

The effects of air flow maldistribution on the performance of an air source heat pump chiller under frosting conditions were investigated experimentally. The results indicated that air flow maldistribution was the dominant factor leading to hunting of the thermostatic expansion valve for medium and/or large size finned tube evaporators. With air flow maldistribution degree (AMD) increasing, frost occurred earlier, and the frost layer grew faster. The operating characteristics became lower when AMD was increased. We found such phenomenon seemed to be related to both the difference of refrigerant outlet superheat and the frosting velocity. In the hunting stage, the frost block effect became the main factor degrading the refrigeration system performance. With AMD increasing, the heat pump system pertinent performance data (suction pressure, evaporation temperature, discharge pressure, refrigerant outlet temperature, etc.) were degraded more dramatically. (author)

Gong, Jianying; Gao, Tieyu; Yuan, Xiuling; Huang, Dong [Department of Refrigeration and Cryogenics, Xi' an Jiao Tong University, Xi' an 710049 (China)

2008-06-15

274

Sublimation behavior of annular frost layer by impinging jet flow; Shototsu funryu ni yoru enkanjo shimoso no shoka tokusei  

Energy Technology Data Exchange (ETDEWEB)

The present paper has dealt with a new method of defrosting by using the frost sublimation phenomenon which occurs below the triple point of water (273.16 K, 610.5 Pa). The present experimental study has focussed to examine the mass transfer of the annular frost layer developed on a cooling pipe exposed to an impinging jet flow. Morphology of the frost layer during sublimating was observed by using a CCD camera. It was understood that the mass flux of the frost layer increased with increasing the jet flow velocity and the difference of the mass concentration of water vapor between the frost surface and the inpinging jet flow. The nondimensional correlation equations of mass transfer of defrosting were derived as functions of various parameters. (author)

Inaba, H.; Horibe, A.; Takamoto, N.; Kawakami, Y. [Okayama University, Okayama (Japan); Imai, S. [Matsushita Refrigeration Co., Osaka (Japan)

2000-10-25

275

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

Science.gov (United States)

Ongoing changes in Arctic sea ice are increasing the spatial and temporal range of young sea ice types over which frost flowers can occur, yet the significance of frost flowers to ocean-sea ice-atmosphere exchange processes remains poorly understood. Frost flowers form when moisture from seawater becomes available to a cold atmosphere and surface winds are low, allowing for supersaturation of the near-surface boundary layer. Ice grown in a pond cut in young ice at the mouth of Young Sound, NE Greenland, in March 2012, showed that expanding frost flower clusters began forming as soon as the ice formed. The new ice and frost flowers dramatically changed the radiative and thermal environment. The frost flowers were about 5°C colder than the brine surface, with an approximately linear temperature gradient from their base to their upper tips. Salinity and ?18O values indicated that frost flowers primarily originated from the surface brine skim. Ikaite crystals were observed to form within an hour in both frost flowers and the thin pond ice. Average ikaite concentrations were 1013 µmol kg-1 in frost flowers and 1061 µmol kg-1 in the surface slush layer. Chamber flux measurements confirmed an efflux of CO2 at the brine-wetted sea ice surface, in line with expectations from the brine chemistry. Bacteria concentrations generally increased with salinity in frost flowers and the surface slush layer. Bacterial densities and taxa indicated that a selective process occurred at the ice surface and confirmed the general pattern of primary oceanic origin versus negligible atmospheric deposition.

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

2014-10-01

276

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

DEFF Research Database (Denmark)

Ongoing changes in Arctic sea ice are increasing the spatial and temporal range of young sea ice types over which frost flowers can occur, yet the significance of frost flowers to ocean-sea ice-atmosphere exchange processes remains poorly understood. Frost flowers form when moisture from seawater becomes available to a cold atmosphere and surface winds are low, allowing for supersaturation of the near-surface boundary layer. Ice grown in a pond cut in young ice at the mouth of Young Sound, NE Greenland, in March 2012, showed that expanding frost flower clusters began forming as soon as the ice formed. The new ice and frost flowers dramatically changed the radiative and thermal environment. The frost flowers were about 5°C colder than the brine surface, with an approximately linear temperature gradient from their base to their upper tips. Salinity and ?18O values indicated that frost flowers primarily originated from the surface brine skim. Ikaite crystals were observed to form within an hour in both frost flowers and the thin pond ice. Average ikaite concentrations were 1013?µmol?kg?1 in frost flowers and 1061?µmol?kg?1 in the surface slush layer. Chamber flux measurements confirmed an efflux of CO2 at the brine-wetted sea ice surface, in line with expectations from the brine chemistry. Bacteria concentrations generally increased with salinity in frost flowers and the surface slush layer. Bacterial densities and taxa indicated that a selective process occurred at the ice surface and confirmed the general pattern of primary oceanic origin versus negligible atmospheric deposition.

Barber, D.; Ehn, J.

2014-01-01

277

Selective inverted sink efficiency for spring frost protection in almond orchards northwest of Isfahan, Iran  

Science.gov (United States)

A so-called selective inverted sink (SIS) was validated in frost protection of a 20-ha almond orchard. Daily counts of flower buds were made for two branches of some selected almond trees in every plot to determine frost damage percentage. Temperatures increased due to the SIS system, but there was an average gradient of temperature decrease of about 0.4°C per 100 m with distance from the SIS. The minimum air temperature increased from 0.5 to 2.8°C, with the highest increase closest to the SIS. The percent of frost-damaged flower buds of almond relative to the control plot with distance to the SIS system had its maximum gradient (8% per 100 m ) in 100-200-m distance from the SIS, but this gradient decreased to a minimum (4% per 100 m) in 500-700-m distance from the SIS. The ANOVA and Duncan's multiple-range test of air temperature and frost damage data confirm that the significant influence zone of this local SIS was about 500 m.

Yazdanpanah, H.; Stigter, C. J.

2011-08-01

278

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

Science.gov (United States)

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

279

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

Science.gov (United States)

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

280

Effect of pyraclostrobin on postharvest storage and quality of sugarbeet harvested before and after a frost  

Science.gov (United States)

Pyraclostrobin and other strobilurin fungicides have been reported to have beneficial effects on productivity that cannot be attributed to disease control. Enhanced late-season frost tolerance is one such effect that has been observed for sugarbeet (Beta vulgaris L.) after a late season foliar pyra...

281

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

Science.gov (United States)

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

282

Control of dew and frost formation on leaf by radiative cooling  

International Nuclear Information System (INIS)

A radiative cooling system was developed to control dew and frost formations and to examine the effect of the radiative cooling on the leaf temperature. The growth chamber was provided with a box which was constructed by using heat insulating materials to minimize the disturbances and to regulate the air current. A cooling coil (cooling surface of 300 cm was equipped at the bottom of the box and manipulated by a refrigerator of 1, 430 kcal hour-1, and a concave mirror was attached to the ceiling of the box to facilitate the reflection of the radiation from the leaf to the cooling coil. The moisture in air was supplied by flowing the controlled air (0.2 m min-1) into the box. The distribution of dew point temperatures was almost uniform horizontally even under vertically slight conversion (downward velocity of 1.3 cm sec-1) of the air. The leaf temperature became about 1.0°C lower than the ambient air temperature under the radiative cooling. The dew and the frost were clearly observed on the leaf after the time when the leaf temperature had become lower than the dew point temperature. The dew increased in size in course of time, and the frost varied in shape and in size with the temperatures. Thus, artificial formations of the dew and the frost were made possible by the radiative cooling system developed in this experiment

283

Frost flower chemical signature in winter snow on Vestfonna ice cap, Nordaustlandet, Svalbard  

Directory of Open Access Journals (Sweden)

Full Text Available The chemistry of snow and ice cores from Svalbard is influenced by variations in local sea ice margin and distance to open water. Snow pits sampled at two summits of Vestfonna ice cap (Nordaustlandet, Svalbard, exhibit spatially heterogeneous soluble ions concentrations despite similar accumulation rates, reflecting the importance of small-scale weather patterns on this island ice cap. The snow pack on the western summit shows higher average values of marine ions and a winter snow layer that is relatively depleted in sulphate. One part of the winter snow pack exhibits a [SO42-/Na+] ratio reduced by two thirds compared with its ratio in sea water. This low sulphate content in winter snow is interpreted as the signature of frost flowers, which are formed on young sea ice when offshore winds predominate. Frost flowers have been described as the dominant source of sea salt to aerosol and precipitation in ice cores in coastal Antarctica but this is the first time their chemical signal has been described in the Arctic. The eastern summit does not show any frost flower signature and we interpret the unusually dynamic ice transport and rapid formation of thin ice on the Hinlopen Strait as the source of the frost flowers.

E. Beaudon

2009-07-01

284

CO2 frost cap thickness on Mars during northern winter and spring  

Science.gov (United States)

The thickness of seasonal CO2 frost that covers the north pole of Mars during the winter and spring seasons is studied using gamma ray and neutron data measured using the gamma ray spectrometer suite of instruments aboard Mars Odyssey. The resultant seasonal variation of CO2 ice/frost thickness for latitudes greater than +85° is in close agreement (within 9% at maximum) with those predicted using all three major Mars general circulation models presently in use. These observed CO2 ice results are significantly different from those inferred from the Mars Obiter Laser Altimeter experiment aboard Mars Global Surveyor (MGS). A possible explanation is that the density of the CO2 ice/frost cap is considerably lower than that inferred from observed variations of the MGS orbit. Other significant results are that the thermal neutron counting rates provide evidence for variations in the abundance of noncondensable components of the polar atmosphere of Mars and that the basement terrain below the seasonal cover of CO2 frost within about 10° of the pole is nearly 100% water ice.

Feldman, W. C.; Prettyman, T. H.; Boynton, W. V.; Murphy, J. R.; Squyres, S.; Karunatillake, S.; Maurice, S.; Tokar, R. L.; McKinney, G. W.; Hamara, D. K.; Kelly, N.; Kerry, K.

2003-09-01

285

High-performance repair mortars for application in severe weathering environments: frost resistance assessment.  

Czech Academy of Sciences Publication Activity Database

Glasgow : University of the West of Scotland, 2013 - (Hughes, J.) ISBN 978-1-903978-44-3 R&D Projects: GA MK(CZ) DF11P01OVV008 Keywords : mortar * frost * durability * hydrophobic Subject RIV: AL - Art, Architecture, Cultural Heritage

K?ivánková, Dana; Nunes, Cristiana Lara; Slížková, Zuzana; Frankeová, Dita; Niedoba, Krzysztof

286

On the need for data for the verification of service life models for frost damage  

DEFF Research Database (Denmark)

The purpose of this paper is to draw the attention to the need for the verification of service life models for frost attack on concrete and the collection of relevant data. To illustrate the type of data needed the paper presents models for internal freeze/thaw damage (internal cracking including de-lamination) and surface scaling.

Geiker, Mette Rica; Engelund, Sven

1999-01-01

287

Frost flower chemical signature in winter snow on Vestfonna ice cap (Nordaustlandet, Svalbard  

Directory of Open Access Journals (Sweden)

Full Text Available The chemistry of snow and ice cores from Svalbard is influenced by variations in local sea ice margin and distance to open water. Snow pits sampled at two summits of Vestfonna ice cap (Nordaustlandet, Svalbard, exhibit spatially heterogeneous soluble ions concentrations despite similar accumulation rates, reflecting the importance of small-scale weather patterns on this island ice cap. The snow pack on the western summit shows higher average values of marine species and a winter snow layer that is relatively depleted in sulphate. One part of the winter snow pack exhibits [SO42-/Na+] ratio reduced by two thirds compared with its ratio in sea water. This low sulphate content in winter snow is interpreted as the signature of frost flowers, which are formed on young sea ice when offshore winds predominate. Frost flowers have been described as the dominant source of sea salt to aerosol and precipitation in ice cores in coastal Antarctica but this is the first time their chemical signal has been described in the Arctic. The eastern summit does not show any frost flower signature and we interpret the unusually dynamic ice transport and rapid formation of thin ice on the Hinlopen Strait as the source of the frost flowers.

E. Beaudon

2009-02-01

288

Satellite prediction of spring frost impacts on vegetation growth and productivity within the conterminous US  

Science.gov (United States)

Spring temperatures strongly influence land surface phenology, including budburst and growing season onset, flowering date, and crop planting period. Recent increases in spring temperatures coincide with earlier and longer non-frozen season trends over the conterminous US and coincide with generally earlier spring canopy onset and annual productivity increases. However, earlier spring onset increases risk of frost damage, with potential negative impacts to productivity. These effects are spatially and temporally heterogeneous, while the occurrence and regional impact of frost events are difficult to monitor from in situ station networks. To enhance regional risk assessment and monitoring capabilities we developed a satellite remote sensing based spring frost index (SFI) and spring frost damage index (SFDI) at moderate (~25-km) spatial resolution from 1980 to 2010. The indices were developed from satellite passive microwave retrievals of global daily landscape freeze-thaw (FT) status and optical-IR sensor derived vegetation start of season (SOS). The SFI is the proportion of the total number of classified frozen (AM and PM frozen) and transitional (AM thawed and PM frozen) frost days in spring (March to May), while the SFDI is the proportion of the total number of classified frozen and transitional frost days following the SOS. The SFI results are validated using surface air temperature records from regional weather stations and crop planting dates for corn and soybean. Our results show a decreasing SFI trend (-2% decade-1; pfrost events, but an earlier SOS is increasing risk of potentially damaging events. The ecological significance of the SFI and SFDI changes were evaluated using satellite annual GPP and NDVI anomalies within the conterminous US. We find that respective SFI and SFDI levels below 10% and 14% have little impact on annual GPP. Reduced SFI and SFDI coincide with enhanced spring vegetation growth, but only the SFDI shows significant correlation with NDVI summer growth anomalies. The SFDI generally provides a better predictor of seasonal NDVI anomalies than the SFI, while vegetation sensitivity to the frost indices varies according to regional biome types and elevation zones. An increasing SFDI trend indicates potentially larger negative impacts on regional vegetation growth with continued warming.

Kim, Y.; Kimball, J. S.; Didan, K.

2013-12-01

289

Frost Damage Detection in Sugarcane Crop Using Modis Images and Srtm Data  

Science.gov (United States)

Brazil is the largest world producer of sugarcane which is used to produce almost equal proportions of either sugar (food) or ethanol (biofuel). In recent years sugarcane crop production has increased fast to meet the growing market demand for sugar and ethanol. This increase has been mainly due to expansion in crop area, but sugarcane production is also subjected to several factors that influence both the agricultural crop yield (tons of stalks/ha) and the industrial yield (kg of sugar/ton of stalks). Sugarcane is a semi-perennial crop that experiences major growth during spring and summer seasons with large demands for water and high temperatures to produce good stalk formation (crop yield). The harvest is performed mainly during fall and winter seasons when water availability and temperature should be low in order to accumulate sucrose in the stalks (industrial yield). These favorable climatic conditions for sugarcane crop are found in several regions in Brazil, particularly in São Paulo state, which is the major sugarcane producer in Brazil being responsible for almost 60% of its production. Despite the favorable climate in São Paulo state there is a certain probability of frost occurrence from time to time that has a negative impact on sugarcane crop, particularly on industrial yield, reducing the amount of sugar in the stalks; having consequences on price increase and product shortage. To evaluate the impact of frost on sugarcane crop, in the field, on a state level, is not a trivial task; however, this information is relevant due to its direct impact on the consumer market. Remote sensing images allow a synoptic view and present great potential to monitor large sugarcane plantations as has been done since 2003 in São Paulo state by the Canasat Project with Landsat type images (http://www.dsr.inpe.br/laf/canasat/en/). Images acquired from sensors with high temporal resolution such as MODIS (Moderate-Resolution Imaging Spectroradiometer) present the potential to detect the impact of climatic effects, such as frost, on crop growth, which is relevant information to evaluate the negative impact on sugarcane production. Thus, the objective of the present study is to detect the impact of the frost occurred on 28 June 2011 in the sugarcane production region of São Paulo state, using MODIS images acquired on board of Terra and Aqua satellites before and after the frost event. Also, Landsat type images were used to map the harvested sugarcane fields up to the frost event based on a sugarcane crop map for year 2011. The remaining sugarcane fields available for harvest in 2011 were monitored with the MODIS images acquired on 17, 19, 27, 28 June and 8 and 9 July, to detect frost damage. Field work was conducted shortly after frost occurrence to identify sugarcane fields with frost damage for training and validation purposes. MODIS images transformed to vegetation indices and morphometric variables extracted from SRTM (Shuttle Radar Topography Mission) data are being analyzed to detect and quantify the damage of the frost from 28 July 2011 on sugarcane crop.

Rudorff, B.; Alves de Aguiar, D.; Adami, M.

2011-12-01

290

Survival, frost susceptibility, growth, and disease resistance of corkbark and subalpine fir grown for landscape and Christmas trees  

Science.gov (United States)

Trees from six corkbark fir (Abies lasiocarpa var. arizonica) and 10 subalpine fir (A. lasiocarpa var. lasiocarpa) seed sources were grown at the University of Idaho Sandpoint Research and Extension Center (SREC) and two commercial nurseries in Idaho and Oregon. Post transplant mortality was highest...

291

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

Science.gov (United States)

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

292

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

Energy Technology Data Exchange (ETDEWEB)

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

293

A statistical evaluation of soil and climatic parameters affecting the change in pavement deflection during thawing of subgrades  

Science.gov (United States)

This report analyzes the results of a field study previously reported by Scrivner et al. (1969) for the National Cooperative Highway Research Program. These authors studied the seasonal pavement deflection characteristics of 24 test sites on roads in service in regions with freezing indexes ranging from 100 F-days to 2100 F-days. They used the Dynaflect cyclic pavement loading device to determine the pavement system response. Of specific interest to my analysis was the increased pavement deflection after freezing and thawing and the time to recovery of normal deflection characteristics. These characteristics were related to soil and climatic factors using statistical techniques. The most significant observations of this statistical analysis are: (1) that the freezing index is not a significant parameter in determining the percent increase in pavement deflection during thawing, and (2) that the recovery time is inversely proportional to the depth of freezing. As was expected, the most significant variable affecting the increase in pavement deflection was the frost susceptibility classification. This observation reinforces the necessity for careful selection of soil materials used in pavement systems.

Chamberlain, E. J.

1981-07-01

294

FROST - FReezing Of coated and uncoated duST particles  

Science.gov (United States)

In April 2008, the measurement campaign FROST (FReezing Of coated and uncoated duST particles) was conducted at the ACCENT (Atmospheric Composition Change - the European NeTwork of excellence) infrastructure site LACIS (Leipzig Aerosol Cloud Interaction Simulator). During the campaign, size selected coated and uncoated Arizona Test Dust (ATD) particles were characterized with respect to shape, chemical composition, hygroscopic growth and activation, and their ability to act as IN (Ice Nuclei). The ATD particles were dispersed by means of a fluidized bed generator. Coatings were applied in different furnaces, operated at different temperatures. The coatings were either succinic acid, sulphuric acid, or ammonium sulphate. A DMA (Differential Mobility Analyzer) was used for selecting particles with a mobility diameter of 300 nm. The following measurements were done: Three AMS (Aerosol Mass Spectrometers, e.g. Schneider et al. (2005) and references therein) were used to determine particle composition. Particles were collected on grids for subsequent TEM (Transmission Electron Micoscropy) analysis. Hygroscopic growth factors were determined by means of a HH-TDMA (High Humidity Tandem Differential Mobility Analyzer) that measured up to relative humidities (RH) of 98% (Hennig et al. (2005)). The critical super-saturations needed for the activation of the investigated particles into cloud droplets were measured with a continuous flow CCNc (Cloud Condensation Nucleus counter) from DMT (Droplet Measurement Technologies, Roberts and Nenes (2005)). The LACIS flow tube was extended to a length of 8 m, so LACIS could be used to examine the immersion freezing behaviour of the coated and uncoated ATD particles. By a bulk analysis and by the AMS measurements, the ATD particles were found to contain water soluble material, however in small quantities. By means of the online AMS measurements, it was possible to distinguish between thin and thick H2SO4 coatings. For the thin coatings, the H2SO4 was found to have reacted with material contained in the ATD, so that almost no free H2SO4 was found. For the thick coatings, obtained at higher coating temperatures, H2SO4 was detected. In general, uncoated particles and those coated with thin coatings of H2SO4 or of succinic acid, showed almost no hygroscopic growth. Particles coated with thicker coatings of H2SO4 and of ammonium sulphate grew noticeably above 95% RH (growth factors of about 1.1 at 98% RH). Both, coated and uncoated ATD particles, were found to activate at atmospherically relevant super-saturations (0.35% for pure ATD, 0.2% for succinic acid and thin H2SO4 coatings, 0.15% for thick H2SO4 and for ammonium sulphate coatings). Combining measured hygroscopic growth with activation data, a dynamic shape factor of the ATD particles of about 1.8 was derived, corroborating the deviation of the particle shape from that of a sphere. Uncoated ATD particles and particles coated with succinic acid or thin coatings of H2SO4 nucleated ice at higher temperatures, i.e. were more efficient IN, than particles with thick H2SO4 or ammonium sulphate coatings. Although the latter two were similar in hygroscopic growth and activation behaviour, they differed in their ability to act as IN, with ATD particles coated with ammonium sulphate being the most ineffective IN. This finding suggests that the investigated particle's ability to act as IN might not be related to water activity for the immersion freezing processes investigated in this study. References: Hennig, T., A. Massling, F. Brechtel, and A. Wiedensohler (2005), A tandem DMA for highly temperature-stabilized hygroscopic particle growth measurements between 90% and 98% relative humidity, J. Aerosol Sci., 36, 10, 1210-1223. Roberts, G., and A. Nenes (2005), A continuous-flow streamwise thermal-gradient CCN chamber for atmospheric measurements, Aerosol Sci. Technol., 39, 206-221. Schneider, J., N. Hock, S. Weimer, S. Borrmann, U. Kirchner, R. Vogt, and V. Scheer (2005), Nucleation particles in Diesel exhaust: Composition inferred from in situ mass sp

Wex, H.

2009-04-01

295

Vacuum pseudoscalar susceptibility  

OpenAIRE

We derive a novel model-independent result for the pion susceptibility in QCD via the isovector-pseudoscalar vacuum polarisation. In the neighbourhood of the chiral-limit, the pion susceptibility can be expressed as a sum of two independent terms. The first expresses the pion-pole contribution. The second is identical to the vacuum chiral susceptibility, which describes the response of QCD's ground-state to a fluctuation in the current-quark mass. In this result one finds a ...

Chang, Lei; Liu, Yu-xin; Roberts, Craig D.; Shi, Yuan-mei; Sun, Wei-min; Zong, Hong-shi

2009-01-01

296

Vacuum pseudoscalar susceptibility  

International Nuclear Information System (INIS)

We derive a novel model-independent result for the pion susceptibility in QCD via the isovector-pseudoscalar vacuum polarization. In the neighbourhood of the chiral limit, the pion susceptibility can be expressed as a sum of two independent terms. The first expresses the pion-pole contribution. The second is identical to the vacuum chiral susceptibility, which describes the response of QCD's ground state to a fluctuation in the current-quark mass. In this result one finds a straightforward explanation of a mismatch between extant estimates of the pion susceptibility.

297

Tier-based approaches for landslide susceptibility assessment in Europe  

OpenAIRE

In the framework of the European Soil Thematic Strategy and the associated proposal of a Framework Directive on the protection and sustainable use of soil, landslides were recognised as a soil threat requiring specific strategies for priority area identification, spatial hazard assessment and management. This contribution outlines the general specifications for nested, Tier-based geographical landslide zonings at small spatial scales to identify priority areas susceptible to landslides (Tier ...

Gunther, Andreas; Reichenbach, Paola; Malet, Jean-philippe; Den Eeckhaut, Miet; Hervas, Javier; Dashwood, Claire; Guzzetti, Fausto

2013-01-01

298

Índice de riesgo sistémico de heladas (IRISH) / Sistemic frost risk index (SFRI)  

Scientific Electronic Library Online (English)

Full Text Available SciELO Venezuela | Language: Spanish Abstract in spanish El objetivo principal de este trabajo es la presentación de los fundamentos y metodología del IRiSH. Se utilizaron temperaturas horarias de cinco observatorios para el período 1991-2003 para calcular la duración de las heladas producidas en ese período y analizar su asociación con la temperatura mín [...] ima. Para el desarrollo del IRiSH se utilizaron las temperaturas mínimas diarias del período 1964-2003. Se asume que las heladas tardías serán tanto más peligrosas cuanto más se adelante la fenología del cultivo o se retrasen las heladas, cuanto mayor sea su intensidad, su duración y su frecuencia. El IRiSH integra todas estas variables directa o indirectamente. Se describen, a modo de ejemplo, las funciones empíricas desarrolladas para el cálculo del índice correspondiente al cultivo de trigo. El resultado es un índice de gran versatilidad, aplicable a distintos cultivos, que tiene en cuenta las principales variables determinantes de la peligrosidad de las heladas. Permite el monitoreo del riesgo de heladas durante el año, así como estudiar su variabilidad interanual, su tendencia temporal y su variación espacial. Con promedios anuales para una serie de años posibilita también la caracterización climática media del riesgo de heladas. Abstract in english The aim of this study is to present the fundamentals and methodology of the SFRi. Hourly temperatures of five observatories for the period 1991-2003 were used to calculate the duration of frosts and analyse their relationship with the minimum temperature. Daily minimum temperatures from the period 1 [...] 964-2003 were used for the development of the SFRi. We assume that late frosts will be more dangerous the sooner the phenology of the crop or the more delayed the frosts, also the greater their intensity, length and frequency. The IRiSH integrates all these variables directly or indirectly. We describe, as an example, the empirical functions developed for calculating the index for wheat cultivation. The result is a versatile index, applicable to different crops, which takes into account the main variables that determine the level of danger from frosts. It allows to monitor frosts risk during the year, and to examine their inter-annual variability, temporal trend and special distribution. With annual averages for many years it also allows for the climatic characterization of frosts risk.

María Elena, Fernández Long; Guillermo, Murphy; María Karina, Torterolo.

2008-03-01

299

Unity of Harmonious Rhythms and the Form in a Poem: an Analysis of Robert Frost’s Stopping by Woods on a Snowy Evening from the angle of rhythms  

OpenAIRE

The rhythms and the form in the poem are mutually dependent .This thesis tries to analyze Robert Frost’s poem Stopping by Woods on a Snowy Evening from the angle of rhythms and appreciate the beauty of the content and the form , which helps to understand the connotation of the poem and reveal the complex feelings of the poet .
Key words: rhythms, the form of the poem
Résumé La rime et la forme dans un poème sont dép...

Du, Min

2006-01-01

300

Frost ring distribution in Araucaria araucana trees from the xeric forests of Patagonia, Argentina Distribución de anillos de heladas en árboles de Araucaria araucana en bosques xéricos de la Patagonia argentina  

OpenAIRE

Frost rings are defined as anatomically abnormal and ecophysiologically pathological structures. We studied frost injuries in tree-rings of Araucaria araucana trees growing at the northern limit of its natural distribution. We recorded 121 frost injuries at two sites in the northern xeric distribution of A. Araucana forests. Frost rings at both sites were primarily restricted to the middle frost ring section of the rings. These results represent the first attempt to report and describe the oc...

Martín Ariel Hadad; Mariano Martín Amoroso; Fidel Alejandro Roig Juñent

2012-01-01

301

Frost Monitoring and Forecasting Using MODIS Land Surface Temperature Data and a Numerical Weather Prediction Model Forecasts for Eastern Africa  

Science.gov (United States)

Frost is a major challenge across Eastern Africa, severely impacting agricultural farms. Frost damages have wide ranging economic implications on tea and coffee farms, which represent a major economic sector. Early monitoring and forecasting will enable farmers to take preventive actions to minimize the losses. Although clearly important, timely information on when to protect crops from freezing is relatively limited. MODIS Land Surface Temperature (LST) data, derived from NASA's Terra and Aqua satellites, and 72-hr weather forecasts from the Kenya Meteorological Service's operational Weather Research Forecast model are enabling the Regional Center for Mapping of Resources for Development (RCMRD) and the Tea Research Foundation of Kenya to provide timely information to farmers in the region. This presentation will highlight an ongoing collaboration among the Kenya Meteorological Service, RCMRD, and the Tea Research Foundation of Kenya to identify frost events and provide farmers with potential frost forecasts in Eastern Africa.

Kabuchanga, Eric; Flores, Africa; Malaso, Susan; Mungai, John; Sakwa, Vincent; Shaka, Ayub; Limaye, Ashutosh

2014-01-01

302

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

Science.gov (United States)

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

303

Comparison of frosting, defrosting and condensate retention characteristics of vertical parallel microgrooved and plain brass surfaces in forced convection condition  

OpenAIRE

In the present study, condensation, frosting and condensate (frost melt water) retention characteristics of brass surfaces with parallel microgrooves have been investigated experimentally and compared with the plain baseline surface. Parallel micro-scale surface features were obtained by a mechanical micromachining process (micro end-milling) without applying any chemical means to modify the surface energy. The surfaces exhibited anisotropic wettability with high stati...

Rahman, Ma; Jacobi, Am

2011-01-01

304

Grand canonical Monte Carlo simulation of adsorption of helium on cryogenic argon frost  

International Nuclear Information System (INIS)

Cryosorption pumping of non-condensable gas, using charcoal, molecular sieves and condensed layers of certain gases, such as Ar, CO2, SF6, and N2, as sorbents, is an efficient method to obtain ultra-high vacuum in cryogenic engineering. Molecular modeling provides a convenient way to understand the principle of adsorption proceeding in microscopic view. Helium adsorption in argon frost at 4.5K has been simulated using the grand canonical Monte Carlo method in this paper. The HFD-B (HE) Aziz potential was used for the He-He pair interaction. The simulated adsorption isotherm of Helium in argon frost was obtained. Additionally, the simulation results were compared with the historic experimental data. (author)

305

USE OF PHASE CHANGE MATERIAL (PCM FOR FROST PREVENTION IN A MODEL GREENHOUSE  

Directory of Open Access Journals (Sweden)

Full Text Available In this study, the possibility of using phase change materials to prevent occurrance of frost in greenhouses during winter was investigated. The melting and freezing temperatures of the PCM were about 8 oC and 4 oC, respectively.The air temperature difference between the PCM and the control greenhouses was about 2oC on average during the day and night time, PCM greenhouse having the higher temperature at night and lower temperature during the day. Frost was prevented on 7 out of 9 occasions, though the temperature difference between the greenhouses was small for some of these days. Solar fraction stored by the PCM store was about 30 %.

Ahmet KÜRKLÜ

1997-02-01

306

Study of the thermal behavior of a latent heat cold storage unit operating under frosting conditions  

International Nuclear Information System (INIS)

A study is performed of the thermal behavior of a latent heat cold storage unit operating under frosting conditions. This unit is employed to maintain the temperature inside the refrigerated compartment of a truck below 265 K. The system consists of parallel plates filled with a phase change material (PCM) that absorbs heat from the flow of warm moist air. A mathematical model for the system is first presented and, next, validated with numerical and experimental data. It is then exploited to assess the effects of design parameters and operating conditions on the performance of the system. The recommended thickness and distance separating the PCM plates are found to be 50x10-3 and 30x10-3 m, respectively. The results indicate that the performance of the unit is enhanced by turbulent air flow in spite of the increased pressure loss and accentuated frost growth. The unit also performs well even when the surrounding relative humidity is 100%

307

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

Directory of Open Access Journals (Sweden)

Full Text Available 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.

M. Piot

2007-04-01

308

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

Directory of Open Access Journals (Sweden)

Full Text Available 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.

M. Piot

2008-05-01

309

Analysis of heat transfer and frost layer formation on a cryogenic tank wall exposed to the humid atmospheric air  

International Nuclear Information System (INIS)

In this paper heat transfer characteristics and frost layer formation are investigated numerically on the surface of a cryogenic oxidizer tank for a liquid propulsion rocket, where a frost layer could be a significant factor in maintaining oxidizer temperature within a required range. Frost formation is modeled by considering mass diffusion of water vapor in the air into the frost layer and various heat transfer modes such as natural and forced convection, latent heat, solar radiation of short wavelength, and ambient radiation of long wavelength. Computational results are first compared with the available measurements and show favorable agreement on thickness and effective thermal conductivity of the frost layer. In the case of the cryogenic tank, a series of parametric studies is presented in order to examine the effects of important parameters such as temperature and wind speed of ambient air, air humidity, and tank wall temperature on the frost layer formation and the amount of heat transfer into the tank. It is found that the heat transfer by solar radiation is significant and also that heat transfer strongly depends on air humidity, ambient air temperature, and wind speed but not tank wall temperature.

310

Fall frost resistance in willows used for biomass production. II. Predictive relationships with sugar concentration and dry matter content.  

Science.gov (United States)

The accumulation of sugars and dry matter in stems in fall was examined in relation to frost hardening in eight willow clones (six clones of Salix viminalis L. and one clone each of S. viminalis x S. schwerenii E. Wolf and S. dasyclados Wimm.). Evidence is presented that three sources of variation in fall frost resistance among the eight clones could be assessed from an analysis of stem composition. First, the pre-hardening value of frost resistance could be assessed from the total sugar concentration. Second, the start of induction of apical growth cessation and hence frost hardening could be distinguished by a stepwise increase in sucrose-to-glucose ratio. Third, the progress of frost hardening during its first phase could be followed from a proportional rise in total sugar concentration and, even more accurately, from a proportional rise in dry-to-fresh weight ratio. In contrast, the second phase of frost hardening was largely uncoupled from sugar and dry matter accumulation. Raffinose and sucrose accumulation seemed to be under differential environmental controls. Sucrose accumulation started with the initiation of growth cessation controlled by photoperiod, whereas raffinose accumulation started with falling temperatures later on. Starch reserves that built up in stems in early fall were partially mobilized later on to support sugar accumulation. In contrast to stems, leaves did not exhibit a preferential accumulation of sucrose in fall. PMID:12651315

Ogren, Erling

1999-09-01

311

Calculation and Analysis of Frost Duration Times by Using Delphi Programming: A Case Study in Lorestan, Iran  

Science.gov (United States)

The purpose of the present study is to calculate the duration times of frosts by Delphi programming. To do this, the data related to the daily minimum temperature of four meteorology stations of Lorestan Province, i.e., Khoram-Abad, Boroujerd, Doroud and Aligoudarz that enjoy a ten-year statistics (from 1993 to 2003) were obtained from the information bank of the National Meteorology Organization. After taking out the frost days in desired threshold (zero and less than zero) during the statistical period, frost duration times of each station were calculated and extracted, using algorithm of the afore-mentioned program. Then, the duration times were selectively divided into eight (three-hour) classes. Their frequency percent charts were drawn and all stations were compared to one another in three classes of 0 to 3 h, 9 to 12 h and 21 to 24 h. It was concluded that Boroujerd Station enjoys the most frost hours and, hence damages to crops were the highest in this station compared with other stations. It was further concluded that the vegetation is the most effective factor in frost duration times of the region and that the height factor has no effect on frost duration times.

Hejazizadeh, Z.; Naserzadeh, M. H.

312

Calculation and Analysis of Frost Duration Times by Using Delphi Programming: A Case Study in Lorestan, Iran  

Directory of Open Access Journals (Sweden)

Full Text Available The purpose of the present study is to calculate the duration times of frosts by Delphi programming. To do this, the data related to the daily minimum temperature of four meteorology stations of Lorestan Province, i.e., Khoram-Abad, Boroujerd, Doroud and Aligoudarz that enjoy a ten-year statistics (from 1993 to 2003 were obtained from the information bank of the National Meteorology Organization. After taking out the frost days in desired threshold (zero and less than zero during the statistical period, frost duration times of each station were calculated and extracted, using algorithm of the afore-mentioned program. Then, the duration times were selectively divided into eight (three-hour classes. Their frequency percent charts were drawn and all stations were compared to one another in three classes of 0 to 3 h, 9 to 12 h and 21 to 24 h. It was concluded that Boroujerd Station enjoys the most frost hours and, hence damages to crops were the highest in this station compared with other stations. It was further concluded that the vegetation is the most effective factor in frost duration times of the region and that the height factor has no effect on frost duration times.

Z. Hejazizadeh

2007-01-01

313

Heat transfer and frost growth on a wind convector based on a row of vertical cylindrical tubes  

Energy Technology Data Exchange (ETDEWEB)

A wind convector is an alternative outdoor heat exchanger for air-source heat pumps which allows transfer of heat from the outdoor environment to an antifreeze solution (brine) without the use of a fan to move the outdoor air across the heat-exchange surfaces. The objectives of this study are to: (a) experimentally investigate the effects of weather conditions on the overall heat transfer coefficient for and frost growth on a wind convector based on a row of vertical cylindrical tubes placed outdoors; and (b) mathematically model the frost growth and heat transfer through the frost layer. An automatically-controlled, microcomputer-monitored outdoor test facility capable of continuous measurement of overall wind-convector heat transfer coefficient, U, to within a measurement uncertainty of {plus minus}3% was built and tested. At the site the following weather conditions are measured: air temperature and humidity, wind speed and direction, solar radiation and rainfall. Frost depth is measured by a computer vision system and frost mass is measured with a weighing cell. Tests of up to 24 hours duration in the unsteady outdoor environment were carried out. Mathematical models of the diffusion-dominated and meltback regimes of frost growth on circular cylinders were developed and compared to experimental measurements.

Monaghan, P.F.

1989-01-01

314

Dissecting the genetic architecture of frost tolerance in Central European winter wheat  

OpenAIRE

Abiotic stress tolerance in plants is pivotal to increase yield stability, but its genetic basis is still poorly understood. To gain insight into the genetic architecture of frost tolerance, this work evaluated a large mapping population of 1739 wheat (Triticum aestivum L.) lines and hybrids adapted to Central Europe in field trials in Germany and fingerprinted the lines with a 9000 single-nucleotide polymorphism array. Additive effects prevailed over dominance effects. A two-dimensional geno...

Zhao, Yusheng; Gowda, Manje; Wu?rschum, Tobias; Longin, C. Friedrich H.; Korzun, Viktor; Kollers, Sonja; Schachschneider, Ralf; Zeng, Jian; Fernando, Rohan; Dubcovsky, Jorge; Reif, Jochen C.

2013-01-01

315

Multitype randomized Reed--Frost epidemics and epidemics upon random graphs  

OpenAIRE

We consider a multitype epidemic model which is a natural extension of the randomized Reed--Frost epidemic model. The main result is the derivation of an asymptotic Gaussian limit theorem for the final size of the epidemic. The method of proof is simpler, and more direct, than is used for similar results elsewhere in the epidemics literature. In particular, the results are specialized to epidemics upon extensions of the Bernoulli random graph.

Neal, Peter

2006-01-01

316

Simulación del depósito de Escarcha en superficies frías Simulation of Frost Deposit in Cold Surfaces  

Directory of Open Access Journals (Sweden)

Full Text Available Se presenta un código computacional que simula la formación y crecimiento de escarcha sobre una placa mantenida a baja temperatura, por ablimación del vapor de agua de una corriente de aire húmedo que fluye sobre ella. La modelación se basa en ecuaciones de conservación de masa, energía, cantidad de movimiento y especies aplicadas a la escarcha, mezcla aire-vapor e interfase aire-escarcha. El sistema de ecuaciones resulta no lineal acoplado por la fracción volumétrica del hielo, que es calculada iterativamente. El modelo es validado frente a datos experimentales, permitiendo reproducir la evolución de propiedades termofísicas de la escarcha formada y predecir comportamientos para otras condiciones de operación. Los resultados revelan mejor concordancia con datos experimentales que la obtenida por otros autores, y levemente inferior a la del modelo de sobresaturación.The development of a computational code that simulates the formation and frost growth on a cool plate, for the vapor-water ablimation of a humid air current that flows on it, is presented. The numeric modeling is based on the conservation equations of mass, energy, momentum and species applied to the frost, air-vapor mixtures and air-frost interface. The system of equations is not linear and is coupled by the ice volumetric fraction which is calculated by iteration. The model is validated by comparing the numerical results with experimental data, reproducing the thermophysical properties evolution of the frost formed and predicting the behavior for other operating conditions. The results reveal better agreement with experimental data that those obtained by other authors, and slightly inferior to that of the supersaturation model.

Jorge A Gatica

2009-01-01

317

TuBaFrost 1: Uniting local frozen tumour banks into a European network: an overview.  

OpenAIRE

TuBaFrost is the consortium responsible for the creation of a virtual European human frozen tumour tissue bank: a collection of high quality frozen residual, accurately classified tumour tissue samples, which are stored in European cancer centres and universities. This virtual tissue bank, searchable on the internet, has rules for access and use, and a code of conduct to comply with the various legal and ethical regulations in European countries. The easy accessibility and the European scale ...

Riegman, Ph; Dinjens, Wn; Oomen, Mh; Spatz, A.; Ratcliffe, C.; Knox, K.; Mager, R.; Kerr, D.; Pezzella, F.; Damme, B.; Vijver, M.; Boven, H.; Morente, Mm; Alonso, S.; Kerjaschki, D.

2006-01-01

318

Simulación del depósito de Escarcha en superficies frías / Simulation of Frost Deposit in Cold Surfaces  

Scientific Electronic Library Online (English)

Full Text Available SciELO Chile | Language: Spanish Abstract in spanish Se presenta un código computacional que simula la formación y crecimiento de escarcha sobre una placa mantenida a baja temperatura, por ablimación del vapor de agua de una corriente de aire húmedo que fluye sobre ella. La modelación se basa en ecuaciones de conservación de masa, energía, cantidad de [...] movimiento y especies aplicadas a la escarcha, mezcla aire-vapor e interfase aire-escarcha. El sistema de ecuaciones resulta no lineal acoplado por la fracción volumétrica del hielo, que es calculada iterativamente. El modelo es validado frente a datos experimentales, permitiendo reproducir la evolución de propiedades termofísicas de la escarcha formada y predecir comportamientos para otras condiciones de operación. Los resultados revelan mejor concordancia con datos experimentales que la obtenida por otros autores, y levemente inferior a la del modelo de sobresaturación. Abstract in english The development of a computational code that simulates the formation and frost growth on a cool plate, for the vapor-water ablimation of a humid air current that flows on it, is presented. The numeric modeling is based on the conservation equations of mass, energy, momentum and species applied to th [...] e frost, air-vapor mixtures and air-frost interface. The system of equations is not linear and is coupled by the ice volumetric fraction which is calculated by iteration. The model is validated by comparing the numerical results with experimental data, reproducing the thermophysical properties evolution of the frost formed and predicting the behavior for other operating conditions. The results reveal better agreement with experimental data that those obtained by other authors, and slightly inferior to that of the supersaturation model.

Jorge A, Gatica; Vicente A, Pita; Nisio de C, Lobo.

319

Risk of spring frost to apple production under future climate scenarios: the role of phenological acclimation  

Science.gov (United States)

In the context of global warming, the general trend towards earlier flowering dates of many temperate tree species is likely to result in an increased risk of damage from exposure to frost. To test this hypothesis, a phenological model of apple flowering was applied to a temperature series from two locations in an important area for apple production in Europe (Trentino, Italy). Two simulated 50-year climatic projections (A2 and B2 of the Intergovernmental Panel on Climate Change - Special Report on Emission Scenarios) from the HadCM3 general circulation model were statistically downscaled to the two sites. Hourly temperature records over a 40-year period were used as the reference for past climate. In the phenological model, the heat requirement (degree hours) for flowering was parameterized using two approaches; static (constant over time) and dynamic (climate dependent). Parameterisation took into account the trees’ adaptation to changing temperatures based on either past instrumental records or the downscaled outputs from the climatic simulations. Flowering dates for the past 40 years and simulated flowering dates for the next 50 years were used in the model. A significant trend towards earlier flowering was clearly detected in the past. This negative trend was also apparent in the simulated data. However, the significance was less apparent when the “dynamic” setting for the degree hours requirement was used in the model. The number of frost episodes and flowering dates, on an annual basis, were graphed to assess the risk of spring frost. Risk analysis confirmed a lower risk of exposure to frost at present than in the past, and probably either constant or a slightly lower risk in future, especially given that physiological processes are expected to acclimate to higher temperatures.

Eccel, Emanuele; Rea, Roberto; Caffarra, Amelia; Crisci, Alfonso

2009-05-01

320

Frosted branch angiitis, neuroretinitis as initial ocular manifestation in Behçet disease  

OpenAIRE

Behçet disease is an idiopathic, multisystem disorder characterized by recurrent episodes of orogenital ulceration and vasculitis of the veins and arteries of all calibers. Ocular involvement may affect the conjunctiva, sclera, uveal tract, vitreous, blood vessels, and retina. Many theories have pointed toward an autoimmune response behind its pathogenesis, which may be triggered by exposure to an infectious agent. Frosted branch angiitis is characterized by vascular inflammation, sheathing,...

Al-mujaini, Abdullah; Wali, Upender K.

2011-01-01

321

ASSESSMENT OF CERAMIC TILE FROST RESISTANCE BY MEANS OF THE FREQUENCY INSPECTION METHOD  

OpenAIRE

The paper presents some results of our experimental analysis of ceramic cladding element frost resistance, particular attention being paid to the application of the frequency inspection method. Three different sets of ceramic tiles of the Ia class to EN 14 411 B standard made by various manufacturers have been analyzed. The ceramic tiles under investigation have been subjected to freeze-thaw-cycle-based degradation in compliance with the relevant ?SN EN ISO 10545-12 standard. Furthermore, ac...

MICHAL MATYSÍK; ZDEN?K CHOBOLA; IVETA PLŠKOVÁ

2011-01-01

322

The risk of early and late frost behavior in central México under El Niño conditions  

Scientific Electronic Library Online (English)

Full Text Available SciELO Mexico | Language: English Abstract in spanish El problema de la presencia irregular de bajas temperaturas (heladas) en el centro de México (~19-23° N) causa pérdidas elevadas en la producción agrícola año tras año, afectando principalmente a cultivos que son sensibles a las temperaturas bajas con importantes implicaciones socioeconómicas. En el [...] centro de México, existe carencia de estudios sobre las heladas en relación a su duración especialmente en respuesta al fenómeno de El Niño (EN). Debido a la accidentada orografía del terreno las estaciones climatológicas se agruparon en rangos de 300 m de altura, resultando cinco regiones: I, III, IV-VI con elevaciones de 875 a 2999 msnm, conformadas por 50 estaciones con datos de temperaturas mínimas diarias ( Abstract in english The irregular occurrence of cold temperatures (frost) in central México (~19-23° N) produces high agricultural losses each year; the greatest effect is on cold-sensitive crops, which has important socio-economic implications for the region. There is a lack of information on frost-related studies reg [...] arding the onset and duration of frosts in central México, especially in response to the El Niño (EN) phenomenon. Due to the land's irregular topography, the weather stations were grouped into 300 m range heights, resulting in five regions: I, III, and IV-VI with elevations from 875 to 2999 masl. Daily minimum temperatures (

A. R, PERALTA-HERNÁNDEZ; L. R, BARBA-MARTÍNEZ.

2009-01-01

323

Numerical heat transfer model for frost protection of citrus fruits by water from a spraying system  

Directory of Open Access Journals (Sweden)

Full Text Available A simplified model is developed to simulate the conditions associated with the protection of fruits from frost damage using water from a spraying system. The model simulates the movement of the solidifying water front on a single fruit, and based on that determines the spray frequency needed for a water film to continuously surround the ice-coated fruit to prevent the fruit temperature from dropping below 0ºC. Simulations are presented for the frost protection of sweet oranges (citrus sinensis. The effect of environmental conditions such as air temperature, air velocity, surface radiation and water film evaporation on the development of the ice layer encasing is considered. Simulations show the effect the encasing ice sheet thickness has on the fruit temperature if water from a spraying system is turned off permanently. Experimental tests are also conducted to determine the change in the thermal properties of citrus sinensis for operating temperatures that range from above freezing to sub-freezing. The results of the experimental tests and the numerical simulations shall lead to a better understanding of fruit protection from frost damage by the application of water from a spraying system.

Issa Roy J.

2012-01-01

324

Five second helium neutral beam injection using argon-frost cryopumping techniques  

International Nuclear Information System (INIS)

High power helium neutral beams for the heating of tokamak discharges can now be provided for 5 s by using argon cryopumping (of the helium gas) in the beamlines. The DIII-D neutral beam system has routinely provided up to 20 MW of deuterium neutral beam heating in support of experiments on the DIII-D tokamak. Operation of neutral beams with helium has historically presented a problem in that pulse lengths have been limited to 500 ms due to reliance solely on volume pumping of the helium gas. Helium is not condensed on the cryopanels. A system has now been installed to deposit a layer of argon frost on the DIII-D neutral beam cryopanels, between tokamak injection pulses. The layer serves to trap helium on the cryopanels providing sufficient pumping speed for 5 s helium beam extraction. The argon frosting hardware is now present on two of four DIII-D neutral beamlines, allowing injection of up to 6 MW of helium neutral beams per discharge, with pulse lengths of up to 5 s. The argon frosting system is described, along with experimental results demonstrating its effectiveness as a method of economically extending the capabilities of cryogenic pumping panels to allow multi-second helium neutral beam injection

325

Proteomic and metabolomic profiling of Valencia orange fruit after natural frost exposure.  

Science.gov (United States)

The aim of this study was to evaluate the response of orange fruit (Citrus sinensis var. Valencia Late) to freezing stress in planta, both immediately after the natural event and after a week, in order to understand the biochemical and molecular basis of the changes that later derive in internal and external damage symptoms. Using two-dimensional differential gel electrophoresis to analyze exposed and non-exposed fruit, 27 differential protein spots were detected in juice sacs and flavedo, among all comparisons made. Also, primary and secondary metabolites relative contents were analyzed in both tissues by gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry, respectively. Proteins and compounds involved in regulatory functions, iron metabolism, oxidative damage and carbohydrate metabolism were the most affected. Interestingly, three glycolytic enzymes were induced by cold, and there was an increase in fermentation products (volatiles); all of that suggests that more energy generation might be required from glycolysis to counter the cold stress. Moreover, a notable increase in sugar levels was observed after frost, but it was not at the expense of organic acids utilization. Consequently, these results suggest a probable redistribution of photoassimilates in the frost-exposed plants, tending to restore the homeostasis altered by that severe type of stress. Isosinensetin was the most cold-sensitive secondary metabolite because it could not be detected at all after the frost, constituting a possible tool to early diagnose freezing damage. PMID:25132553

Perotti, Valeria E; Moreno, Alejandra S; Trípodi, Karina E J; Meier, Guillermo; Bello, Fernando; Cocco, Mariángeles; Vázquez, Daniel; Anderson, Catalina; Podestá, Florencio E

2015-03-01

326

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

Science.gov (United States)

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

327

Aclimatação ao frio e dano por geada em canola Acclimatization to cold and frost-injury in canola  

Directory of Open Access Journals (Sweden)

Full Text Available O objetivo deste trabalho foi avaliar a influência da aclimatação ao frio sobre o dano causado pela geada em diferentes estádios fenológicos de genótipos de canola. Foram realizados cinco experimentos em ambiente controlado, em 2006, 2007 e 2008. Os fatores avaliados foram: genótipos, aclimatação (com; sem, intensidades de geada, estádios de desenvolvimento de plantas, regimes de aclimatação e regimes de geada. As variáveis avaliadas foram: queima de folhas, massa de matéria seca, estatura de plantas, duração de subperíodo, componentes de rendimento e rendimento de grãos. A aclimatação ao frio, antes da geada, resultou em menor queima de folhas e maior massa de matéria seca, em comparação a plantas não aclimatadas. As geadas foram prejudiciais a partir de -6°C no início do ciclo de desenvolvimento, principalmente em plantas não aclimatadas, e a partir de -4ºC na floração, com redução do número de síliquas e do número de grãos por síliqua. A aclimatação após as geadas não contribuiu para a tolerância da canola a esse evento. Geadas consecutivas não acarretaram maior prejuízo à canola. A aclimatação de plantas de canola antes da geada reduz os danos, principalmente quando a geada ocorre no início do desenvolvimento das plantas.The objective of this work was to evaluate the influence of cold acclimatization on frost damage at different phenological stages of canola genotypes. Five experiments were carried out under controlled conditions, in 2006, 2007, and 2008. The evaluated factors were: genotypes, acclimatization (with; without, frost gradient, plant developmental stages, acclimatization regimes and frost regimes. The evaluated variables were: leaf scorching symptoms, dry weight, plant height, length of subperiod, yield components and grain yield. The acclimatization before frost resulted in lesser leaf scorching symptoms and higher dry matter in comparison to plants not acclimated. Frosts were harmful from -6°C in early plant development stage, mainly in nonacclimated plants, and from -4ºC at flowering, reducing the number of pods and the number of grains per pod. Acclimatization after frost did not contribute to the tolerance of canola to frost. Consecutive frosts caused no greater impairment to canola. The canola acclimatization before frost reduces damage caused by it, mainly when the frost occur in the initial plant development stages.

Genei Antonio Dalmago

2010-09-01

328

Aclimatação ao frio e dano por geada em canola / Acclimatization to cold and frost-injury in canola  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese O objetivo deste trabalho foi avaliar a influência da aclimatação ao frio sobre o dano causado pela geada em diferentes estádios fenológicos de genótipos de canola. Foram realizados cinco experimentos em ambiente controlado, em 2006, 2007 e 2008. Os fatores avaliados foram: genótipos, aclimatação (c [...] om; sem), intensidades de geada, estádios de desenvolvimento de plantas, regimes de aclimatação e regimes de geada. As variáveis avaliadas foram: queima de folhas, massa de matéria seca, estatura de plantas, duração de subperíodo, componentes de rendimento e rendimento de grãos. A aclimatação ao frio, antes da geada, resultou em menor queima de folhas e maior massa de matéria seca, em comparação a plantas não aclimatadas. As geadas foram prejudiciais a partir de -6°C no início do ciclo de desenvolvimento, principalmente em plantas não aclimatadas, e a partir de -4ºC na floração, com redução do número de síliquas e do número de grãos por síliqua. A aclimatação após as geadas não contribuiu para a tolerância da canola a esse evento. Geadas consecutivas não acarretaram maior prejuízo à canola. A aclimatação de plantas de canola antes da geada reduz os danos, principalmente quando a geada ocorre no início do desenvolvimento das plantas. Abstract in english The objective of this work was to evaluate the influence of cold acclimatization on frost damage at different phenological stages of canola genotypes. Five experiments were carried out under controlled conditions, in 2006, 2007, and 2008. The evaluated factors were: genotypes, acclimatization (with; [...] without), frost gradient, plant developmental stages, acclimatization regimes and frost regimes. The evaluated variables were: leaf scorching symptoms, dry weight, plant height, length of subperiod, yield components and grain yield. The acclimatization before frost resulted in lesser leaf scorching symptoms and higher dry matter in comparison to plants not acclimated. Frosts were harmful from -6°C in early plant development stage, mainly in nonacclimated plants, and from -4ºC at flowering, reducing the number of pods and the number of grains per pod. Acclimatization after frost did not contribute to the tolerance of canola to frost. Consecutive frosts caused no greater impairment to canola. The canola acclimatization before frost reduces damage caused by it, mainly when the frost occur in the initial plant development stages.

Genei Antonio, Dalmago; Gilberto Rocca da, Cunha; Anderson, Santi; João Leonardo Fernandes, Pires; Alexandre Luiz, Müller; Laise Maria, Bolis.

2010-09-01

329

Association analysis of frost tolerance in rye using candidate genes and phenotypic data from controlled, semi-controlled, and field phenotyping platforms  

OpenAIRE

Abstract Background Frost is an important abiotic stress that limits cereal production in the temperate zone. As the most frost tolerant small grain cereal, rye (Secale cereale L.) is an ideal cereal model for investigating the genetic basis of frost tolerance (FT), a complex trait with polygenic inheritance. Using 201 genotypes from five Eastern and Middle European winter rye populations, this study reports a multi-platform candidate gene-based association analysis in rye using 161 single nu...

Li Yongle; Böck Andreas; Haseneyer Grit; Korzun Viktor; Wilde Peer; Schön Chris-Carolin; Ankerst Donna P; Bauer Eva

2011-01-01

330

Agricultural losses related to frost events: use of the 850 hPa level temperature as an explanatory variable of the damage cost  

OpenAIRE

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 t...

Papagiannaki, K.; Lagouvardos, K.; Kotroni, V.; Papagiannakis, G.

2014-01-01

331

Evaluación de daños por heladas tardías en ensayos de procedencias de pino oregón introducidos en el norte de la Región Andino Patagónica Argentina / Evaluation of damage by late frosts in provenances trials of Douglas-fir introduced in Argentinian North Patagonia  

Scientific Electronic Library Online (English)

Full Text Available SciELO Chile | Language: Spanish Abstract in spanish La susceptibilidad a las heladas tardías de la fuente de semilla actualmente utilizada es una de las principales características adaptativas que limitan la ampliación del área de plantación de pino oregón (Pseudotsuga menziesii (Mirb.) Franco) en la Región Norpatagónica de la Argentina. En dos ensay [...] os de procedencias de esta especie se registró el daño provocado por heladas de primavera de hasta -7º C de mínima absoluta. En ambos ensayos se encontraron diferencias significativas entre los tratamientos. En el ensayo en el que se registraron mínimas más rigurosas pudieron establecerse correlaciones altamente significativas entre el porcentaje de daño por heladas con la longitud (r = 0,86) y altitud (r = - 0,75) del origen de la semilla, y una menor asociación con la altura media de las plantas en vivero (r = 0,55) y la latitud de origen (r = 0,44). Considerando que los orígenes costeros son los de mayor potencial de crecimiento, estos resultados indican que la selección en base a ese único criterio podría producir una selección indirecta de genotipos susceptibles. Finalmente se recomienda la evaluación simultánea de rendimiento y susceptibilidad para extender el cultivo de la especie hacia áreas de mayor riesgo de heladas. Abstract in english The susceptibility to late frost of the seed source used for afforestations at the moment it is one of the main adaptatives characteristic limiting the increase of the planted area of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) in Argentinien North Patagonia Region. In two provenances trials [...] of this species we registered frost injury caused by absolute minimum temperature of -7º C during spring. In both sites we found significant differences among treatments. We found a strong correlation between the percentage of frost injury and seed source longitude (r = 0.86) and with seed source altitude (r = 0.75) in the trail that registered the most rigorous minimum. In this trial we found also a weaker association with nursery mean heights (r = 0.55) and the origin latitude (r = 0.44). Considering that coastal origins are those of better potential growth, selection based only growth criteria could produce an indirect selection of susceptible genotypes. Finally we recommend the simultaneous evaluation of yield and susceptibility to be able to extend the specie cultivation towards other areas with increased frost risks.

ALEJANDRO, MARTINEZ MEIER; VICTOR, MONDINO; LEONARDO, GALLO.

2005-12-01

332

Evaluación de daños por heladas tardías en ensayos de procedencias de pino oregón introducidos en el norte de la Región Andino Patagónica Argentina Evaluation of damage by late frosts in provenances trials of Douglas-fir introduced in Argentinian North Patagonia  

Directory of Open Access Journals (Sweden)

Full Text Available La susceptibilidad a las heladas tardías de la fuente de semilla actualmente utilizada es una de las principales características adaptativas que limitan la ampliación del área de plantación de pino oregón (Pseudotsuga menziesii (Mirb. Franco en la Región Norpatagónica de la Argentina. En dos ensayos de procedencias de esta especie se registró el daño provocado por heladas de primavera de hasta -7º C de mínima absoluta. En ambos ensayos se encontraron diferencias significativas entre los tratamientos. En el ensayo en el que se registraron mínimas más rigurosas pudieron establecerse correlaciones altamente significativas entre el porcentaje de daño por heladas con la longitud (r = 0,86 y altitud (r = - 0,75 del origen de la semilla, y una menor asociación con la altura media de las plantas en vivero (r = 0,55 y la latitud de origen (r = 0,44. Considerando que los orígenes costeros son los de mayor potencial de crecimiento, estos resultados indican que la selección en base a ese único criterio podría producir una selección indirecta de genotipos susceptibles. Finalmente se recomienda la evaluación simultánea de rendimiento y susceptibilidad para extender el cultivo de la especie hacia áreas de mayor riesgo de heladas.The susceptibility to late frost of the seed source used for afforestations at the moment it is one of the main adaptatives characteristic limiting the increase of the planted area of Douglas-fir (Pseudotsuga menziesii (Mirb. Franco in Argentinien North Patagonia Region. In two provenances trials of this species we registered frost injury caused by absolute minimum temperature of -7º C during spring. In both sites we found significant differences among treatments. We found a strong correlation between the percentage of frost injury and seed source longitude (r = 0.86 and with seed source altitude (r = 0.75 in the trail that registered the most rigorous minimum. In this trial we found also a weaker association with nursery mean heights (r = 0.55 and the origin latitude (r = 0.44. Considering that coastal origins are those of better potential growth, selection based only growth criteria could produce an indirect selection of susceptible genotypes. Finally we recommend the simultaneous evaluation of yield and susceptibility to be able to extend the specie cultivation towards other areas with increased frost risks.

ALEJANDRO MARTINEZ MEIER

2005-12-01

333

Group for frozen soil and rock  

Science.gov (United States)

The American Society for Testing and Materials wants participants for D18.19, its new subcommittee on frozen soil and rock. The group will write standards for engineering practices in northern Canada, Alaska, and other areas where soil and rock are commonly in the frozen or recently thawed state. Three standards are currently under development: axial compressive load tests o n piles in frozen soils, laboratory rate of frost-heave tests, and laboratory creep testing of frozen soil.The next D18.19 meeting is June 26 in St. Louis, Mo. Scientists who want to work on the subcommittee should contact Bill Lovell, School of Civil Engineering, Purdue University, West Lafayette, IN 47904, tel. 317-494- 5034; or Wendy Dyer, ASTM, 1916 Race Street, Philadelphia, PA 19103, tel. 215-299-5526.

334

Unity of Harmonious Rhythms and the Form in a Poem: an Analysis of Robert Frost’s Stopping by Woods on a Snowy Evening from the angle of rhythms  

Directory of Open Access Journals (Sweden)

Full Text Available The rhythms and the form in the poem are mutually dependent .This thesis tries to analyze Robert Frost’s poem Stopping by Woods on a Snowy Evening from the angle of rhythms and appreciate the beauty of the content and the form , which helps to understand the connotation of the poem and reveal the complex feelings of the poet .
Key words: rhythms, the form of the poem
Résumé La rime et la forme dans un poème sont dépendantes mutuellement. L’article essaie d’analyser le poème S’arrêter au bord de la forêt dans une nuit de neige de Robert Frost du point de vue de la rime et interpreter la forme de sa rime pour apprécier les beautés du contenu et de la forme du poème, cela favorise la révélation de la signification du poème et des sentiments complexes du poète.
Mots clés: la rime, la forme du poème
? ? ?????????????????????????????????????????????????????????????????????????????????????????????????
?????????

Min DU

2006-03-01

335

Development of a Frost Risk Assessment Tool in Agriculture for a Mediterranean ecosystem Utilizing MODIS satellite observations Geomatics and Surface Data  

Science.gov (United States)

Frost risk in Mediterranean countries is a critical factor in agricultural planning and management. Nowadays, the rapid technological developments in Earth Observation (EO) technology have improved dramatically our ability to map the spatiotemporal distribution of frost conditions over a given area and evaluate its impacts on the environment and society. In this study, a frost risk model for agricultural crops cultivated in a Mediterranean environment has been developed, based primarily on Earth Observation (EO) data from MODIS sensor and ancillary spatial and point data. The ability of the model to predict frost conditions has been validated for selected days on which frost conditions had been observed for a region in Northwestern Greece according to ground observations obtained by the Agricultural Insurance Organization (ELGA). An extensive evaluation of the frost risk model predictions has been performed herein to evaluate objectively its ability to predict the spatio-temporal distribution of frost risk in the studied region, including comparisons against physiographical factors of the study area. The topographical characteristics that were taken under consideration were latitude, altitude, slope steepness, topographic convergence and the extend of the areas influenced by water bodies (such as lake and sea) existing in the study area. Additional data were also used concerning land use data and vegetation classification (type and density). Our results showed that the model was able to produce reasonably the spatio-temporal distribution of the frost conditions in our study area, following largely explainable patterns in respect to the study site and local weather conditions characteristics. All in all, the methodology implemented herein proved capable in obtaining rapidly and cost-effectively cartography of the frost risk in a Mediterranean environment, making it potentially a very useful tool for agricultural management and planning. The model presented here has also a potential to enhance conventional field-based surveying for monitoring frost changes over long timescales. KEYWORDS: Earth Observation, MODIS, frost, risk assessment, Greece

Louka, Panagiota; Papanikolaou, Ioannis; Petropoulos, George; Migiros, George; Tsiros, Ioannis

2014-05-01

336

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

Energy Technology Data Exchange (ETDEWEB)

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

337

Evaluations on power ramp data of PWR fuels by FROST and THERMOST codes  

International Nuclear Information System (INIS)

Power ramp data of Mitsubishi's PWR fuel rods tested in R-2, Studsvik were analyzed by FROST and THERMOST codes. The predictions of both codes show relatively good agreement with many measurements during or after irradiation. Especially detailed behaviours of the fuel related to axial PCMI, such as rod elongation-relaxation during ramp test, are predicted successfully. Axial and radial deformations of claddings are simulated so well that calculated stresses in claddings are considered to be reliable. The ramp data used in present analyses were obtained in two joint programs with five Japanese PWR utilities (KEPCO, KYEPCO, SEPCO, HEPCO, and JAPCO). (author)

338

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

International Nuclear Information System (INIS)

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

339

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

International Nuclear Information System (INIS)

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.

340

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

International Nuclear Information System (INIS)

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. 14 refs

341

CLAS+FROST: new generation of photoproduction experiments at jefferson lab  

International Nuclear Information System (INIS)

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. (author)

342

Helium pumping by argon frosting on a 4.5 K surface  

International Nuclear Information System (INIS)

Pumping of helium gas by means of argon frosting on a bare copper surface cooled to ?4.5 K has been investigated in one of the neutral beamlines of the DIII-D tokamak. The beamline is designed to handle high power hydrogen and deuterium beams and corresponding high gas feed rates. By prefrosting the cryo panels with argon in an actual beamline, multi-second helium gas pulses have been handled at a background gas pressure low enough for formation and transport of helium beams. Appreciable pumping of helium gas was observed even at an argon-to-helium ratio as low as 20. 16 refs., 5 figs

343

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

International Nuclear Information System (INIS)

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 I 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

344

Use of Gibberellins to Improve Fruit Set in Pears After Frost Damage  

OpenAIRE

The objectives of this study were to investigate the effect of applied bioregulators on fruit set after this frost in April 2002, growth, yield and the incidence of Pseudomonas syringae and the understanding of the underlying mechanisms of fruit set by applying bioregulators shortly after full bloom at the Klein-Altendorf experimental station near Bonn, Germany with the following results. The best fruit set was achieved with both GA3 and GA3 plus 0.5l GA4+7 sprayed at 12 mL ha-1 which increas...

George Ouma

2008-01-01

345

Experimental frost-bite in Hanford Miniature Swine. I. Epithelial changes.  

OpenAIRE

Frost-bite lesions were produced in five Hanford Miniature Swine exposed to - 75 degrees C air for 1, 3, 5, 10 or 20 min. Biopsies were taken at 0, 3, 6, 12, 24 and 48 h and 1 and 2 weeks. Two hundred slides were evaluated microscopically: pyknosis, vacuolation, individualization of cells, and degeneration were graded from 0-5; 0, no change; 5, severe change. Necrosis, new epithelium, and microabscesses were recorded as present or absent. Early changes of vacuolation of keratinocytes, individ...

Schoning, P.; Hamlet, M. P.

1989-01-01

346

Experimental frost-bite in Hanford Miniature Swine. III. Sweat gland changes.  

OpenAIRE

Frost-bite was produced in five Hanford Miniature Swine by exposure to -75 degrees C air for 1, 3, 5, 10 or 20 min. Biopsies were taken at 0, 3, 6, 12, 24 and 48 h and 1, 2 and 15 weeks. Sweat glands were evaluated microscopically and graded: 0, no change to 5, severe change. Sweat gland changes were mild by 1 h and moderate by 24 h for all freeze groups, except the 1-min freeze group. Severe morphological changes were of two types: degeneration/necrosis and squamous metaplasia. These changes...

Schoning, P.

1990-01-01

347

Experimental frost-bite in Hanford Miniature Swine. II. Vascular changes.  

OpenAIRE

Frost-bite lesions were produced in five Hanford Miniature Swine exposed to - 75 degrees C air for 1, 3, 5, 10, or 20 min. Biopsies were taken at 0, 3, 6, 12, 24, and 48 h, and 1 and 2 weeks. Two hundred slides were evaluated microscopically: superficial and deep hyperaemia, vascular inflammation, medial degeneration, and thrombosis were graded from 0 to 5; 0, no change; 5, severe change. Haemorrhage was recorded as present or absent. Hyperaemia was the earliest change seen, both grossly and ...

Schoning, P.; Hamlet, M. P.

1989-01-01

348

Helium pumping by argon frosting on a 4.5 K surface  

International Nuclear Information System (INIS)

Pumping of helium gas by means of argon frosting on a bare copper surface cooled to ?4.5 K has been investigated in one of the neutral beamlines of the DIII-D tokamak. The beamline is designed to handle high power hydrogen and deuterium beams and corresponding high gas feed rates. By prefrosting the cryo panels with argon in an actual beamline, multisecond helium gas pulses have been handled at a background gas pressure low enough for formation and transport of helium beams. Appreciable pumping of helium gas was observed even at an argon-to-helium ratio as low as 20

349

Theoretical and experimental studies of the influence of frost formation on evaporator heat exchange surfaces  

Energy Technology Data Exchange (ETDEWEB)

The most significant results are given on a theoretical/experimental research program carried out by LU-VE Contardo together with the Department of Energy of the Polytechnic Inst. of Milan. It concerns the energetic and operational problems deriving from frost formation on the heat exchange surfaces of air evaporators. In the first part of the paper, a calculation methodology is described and the calculation results obtained from experimental data are compared. In the second part, a procedure is proposed, based on the use of a microprocessor capable of varying defrosting intervals according to an 'intelligent' logic which optimizes the overall energetic performance of a cooling plant.

Macchi, E.; Perfetti, C.; Solaro, M. (Politecnico di Milano, Milan (Italy))

1989-10-01

350

Clay mineralogy and magnetic susceptibility of Oxisols in geomorphic surfaces  

Scientific Electronic Library Online (English)

Full Text Available Studies analyzing the variability of clay minerals and magnetic susceptibility provide data for the delineation of site-specific management areas since many of their attributes are important to agronomy and the environment. This study aimed to evaluate the spatial variability of clay minerals, magne [...] tic susceptibility, adsorbed phosphorus and physical attributes in Oxisols of sandstones in different geomorphic surfaces. For that purpose, soil samples were collected every 25 m along a transect located within the area where the geomorphic surfaces were identified and mapped. The transect occupied the central portion of 500 ha, where it was also sampled for density purposes with one sample per six hectares. Soil samples were collected at a depth of 0.0-0.2 m. The results of the physical, chemical, mineralogical and magnetic susceptibility analyses were subjected to statistical and geostatistical analyses. The nature of the clay minerals and magnetic susceptibility was dependent on the variation of the soil parent material. High values of magnetic susceptibility were associated with the presence of maghemite and magnetite of coarse size. The spatial variability of crystallinity and the content of Fe oxides, as well as magnetic susceptibility, were dependent on the age of the geomorphic surfaces. The youngest surface had greater spatial variability of these attributes. The iron (goethite and hematite) and aluminum (gibbsite) oxides in the youngest geomorphic surface influenced the low values of soil density and high values of total pore volume, micropores and P adsorption. The characterization of the spatial variability of Fe oxides and susceptibility allowed for the delineation of homogeneous areas.

Livia Arantes, Camargo; José, Marques Júnior; Gener Tadeu, Pereira; Angélica Santos Rabelo de Souza, Bahia.

2014-06-01

351

Effects of fin pitch and array of the frost layer growth on extended surface of a heat exchanger  

International Nuclear Information System (INIS)

This paper presents the effects of the fin array and pitch on the frost layer growth of a heat exchanger. The numerical results are compared with experimental data of a cold plate to validate the present model, and agree well with experimental data within a maximum error of 8%. The characteristics of the frost formation on staggered fin array are somewhat different from those of in-line array. For fin pitch below 10 mm, the frost layer growth of second fin in the staggered array is affected by that of first fin. The heat transfer of single fin deteriorate with decreasing fin pitch regardless of fin array, however, the thermal performance of a heat exchanger, considering increase of heat surface area, becomes better

352

Heat transfer characteristics of spirally-coiled circular fin-tube heat exchangers operating under frosting conditions  

Energy Technology Data Exchange (ETDEWEB)

The objective of this study is to investigate the heat transfer characteristics of spirally-coiled circular fin-tube heat exchangers under frosting conditions. The heat transfer rate, pressure drop, frost thickness, and Nusselt number of the heat exchanger were measured and analyzed by varying the fin pitch and number of tube rows under frosting conditions. In addition, the Nusselt number of the spirally-coiled circular fin-tube exchanger was compared with those of flat plate fin-tube heat exchangers with discrete fins. An empirical correlation of the Nusselt number was developed as a function of the Reynolds number, dimensionless fin pitch normalized by the hydraulic diameter, i.e., D{sub h}/F{sub p}, Fourier number, and number of tube rows. The measured Nusselt number was consistent with the predicted value with mean and average deviations of 3.5% and 0.3%, respectively. (author)

Lee, Mooyeon; Kang, Taehyung; Joo, Youngju [Graduate School of Mechanical Engineering, Korea University, Anam-dong, Sungbuk-ku, Seoul 136-713 (Korea, Republic of); Kim, Yongchan [Department of Mechanical Engineering, Korea University, Anam-dong, Sungbuk-ku, Seoul 136-713 (Korea, Republic of)

2011-01-15

353

The cold dependent accumulation of COR TMC-AP3 in cereals with contrasting, frost tolerance is regulated by different mRNA expression and protein turnover.  

Science.gov (United States)

The accumulation of specific cold-regulated (COR) proteins is a component of the hardening process and different amount of COR proteins has been related to different degrees of cold tolerance. A number of different mechanisms controls the accumulation of the COR proteins in the plant cells. In this work we describe the mechanisms controlling the accumulation of the COR protein TMC-AP3, a putative chloroplastic amino acid selective channel protein [1] in barley, durum, wheat, emmer and bread wheat. Winter barley and, to less extent, winter bread wheat showed a higher cor tmc-ap3 expression at low temperature than the spring one while no significant differences were detected between the emmer and the durum. wheat genotypes. After 2 days of de-hardening the transcript level dropped down in the same way in all tested genotypes, nevertheless the decrease in protein content was genotype dependent. In all frost resistant genotypes the amount of COR TMC-AP3 after 9 days of de-hardening was higher compared with that of susceptible ones. These findings suggest that resistant and susceptible genotypes have different protein degradation rate and/or mRNA translational efficiency. Differences in the protein degradation rate were not dependent from the amino acidic sequence of the protein, being extremely similar in all tested genotypes. A genetic study based on Chinese spring/Cheyenne chromosome substitution lines showed that the turnover of TMC-AP3 is a polygenic trait controlled by a number of loci being the most important located on chromosomes 1B, 2B, 2D and 4D. PMID:10908804

Maria Mastrangelo A; Baldi; Marè; Terzi; Galiba; Cattivelli; Di Fonzo N

2000-07-14

354

Soil physical properties affecting soil erosion in tropical soils  

International Nuclear Information System (INIS)

The total vegetated land area of the earth is about 11,500 hectare. Of this, about 12% is in South America. Of this, about 14% is degraded area. Water erosion, chemical degradation, wind erosion, and physical degradation have been reported as main types of degradation. In South America water erosion is a major process for soil degradation. Nevertheless, water erosion can be a consequence of degradation of the soil structure, especially the functional attributes of soil pores to transmit and retain water, and to facilitate root growth. Climate, soil and topographic characteristics determine runoff and erosion potential from agricultural lands. The main factors causing soil erosion can be divided into three groups: Energy factors: rainfall erosivity, runoff volume, wind strength, relief, slope angle, slope length; Protection factors: population density, plant cover, amenity value (pressure for use) and land management; and resistance factors: soil erodibility, infiltration capacity and soil management. The degree of soil erosion in a particular climatic zone, with particular soils, land use and socioeconomic conditions, will always result from a combination of the above mentioned factors. It is not easy to isolate a single factor. However, the soil physical properties that determine the soil erosion process, because the deterioration of soil physical properties is manifested through interrelated problems of surface sealing, crusting, soil compaction, poor drainage, impeded root growth, excessive runoff and accelerated erosion. When an unprotected soil surface is exposed to the direct impact of raindrops it can produce different responses: Production of smaller aggregates, dispersed particles, particles in suspension and translocation and deposition of particles. When this has occurred, the material is reorganized at the location into a surface seal. Aggregate breakdown under rainfall depends on soil strength and a certain threshold kinetic energy is needed to start detachment. Studies on necessary kinetic energy to detach one kilogram of sediments by raindrop impact have shown that the minimum energy is required for particles of 0.125 mm. Particles between 0.063 to 0.250 mm are the most vulnerable to detachment. This means that soils with high content of particles into vulnerable range, for example silty loam, loamy, fine sandy, and sandy loam are the most susceptible soils to detachment. Many aspects of soil behaviour in the field such as hydraulic conductivity water retention, soil crusting, soil compaction, and workability are influenced strongly by the primary particles. In tropical soils also a negative relation between structure stability and particles of silt, fine sand and very fine sand has been found, this is attributed to low cohesiveness of these particles. The ability of a structure to persist is known as its stability. There are two principal types of stability: the ability of the soil to retain its structure under the action of water, and the ability of the soil to retain its structure under the action of external mechanical stresses. (e.g. by wheels). Both types of stability are related with susceptibility to erosion

355

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

Science.gov (United States)

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.

356

Improving Freezing Tolerance of Cultivated Potatoes: Moving Frost Hardy Genes From Wild Potatoes and Making Real Progress Using Precise Screening Tools  

Science.gov (United States)

The common cultivated species Solanum tubrosum is frost sensitive and is killed at temperatures below -2.5°C. It has been estimated that by increasing frost hardiness by 1–2 C one can expect an increase in potato yield by 26 to 40% in the Altiplano (Peru and Bolivia) covering 63,000 ha. of potatoes....

357

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

Science.gov (United States)

We propose a conceptual model of sublimation/condensation (or decrease/increase of mass or extent) of CO2 frost and H2O frost/ice within a crater with observed high albedo deposits in later spring to middle summer.

Xie, H.; Guan, H.; Zhu, M.; Thueson, M.

2007-03-01

358

Performance comparison of air source heat pump with R407C and R22 under frosting and defrosting  

International Nuclear Information System (INIS)

The dynamic performance characteristics of the air source heat pump (ASHP) with refrigerants R22 and R407C during frosting and defrosting are studied. The results show that both refrigerant systems have similar performance characteristics, except that the performance of the R407C system deteriorated faster than that of the R22 system under frosting, and the performance of the R407C system attains its steady state faster than that of the R22 system after defrosting. R407C refrigerant can be used in either existing systems or in new systems that were originally designed for R22

359

TuBaFrost 3: regulatory and ethical issues on the exchange of residual tissue for research across Europe.  

OpenAIRE

The regulatory regimes for research with residual tissue and accompanying data differ widely between countries in the European Union (EU): from specific consent to opt-out or even no consent at all. This could greatly hamper research where the exchange of tissue and accompanying data has become the gold standard, like in TubaFrost. Instead of adhering to international guidelines, which have a democratic deficit, or an attempt for a new set of possible harmonising rules, TubaFrost chose to cre...

Veen, Eb; Riegman, Ph; Dinjens, Wn; Lam, Kh; Oomen, Mh; Spatz, A.; Mager, R.; Ratcliffe, C.; Knox, K.; Kerr, D.; Damme, B.; Vijver, M.; Boven, H.; Morente, Mm; Alonso, S.

2006-01-01

360

TuBaFrost 2: Standardising tissue collection and quality control procedures for a European virtual frozen tissue bank network.  

OpenAIRE

Tumour Bank Networking presents a great challenge for oncological research as in order to carry out large-scale, multi-centre studies with minimal intrinsic bias, each tumour bank in the network must have some fundamental similarities and be using the same standardised and validated procedures. The European Human Frozen Tumour Tissue Bank (TuBaFrost) has responded to this need by the promotion of an integrated platform of tumour banks in Europe. The operational framework for TuBaFrost has dra...

Morente, Mm; Mager, R.; Alonso, S.; Pezzella, F.; Spatz, A.; Knox, K.; Kerr, D.; Dinjens, Wn; Oosterhuis, Jw; Lam, Kh; Oomen, Mh; Damme, B.; Vijver, M.; Boven, H.; Kerjaschki, D.

2006-01-01

361

Calculation and Analysis of Frost Duration Times by Using Delphi Programming: A Case Study in Lorestan, Iran  

OpenAIRE

The purpose of the present study is to calculate the duration times of frosts by Delphi programming. To do this, the data related to the daily minimum temperature of four meteorology stations of Lorestan Province, i.e., Khoram-Abad, Boroujerd, Doroud and Aligoudarz that enjoy a ten-year statistics (from 1993 to 2003) were obtained from the information bank of the National Meteorology Organization. After taking out the frost days in desired threshold (zero and less than zero) during the statis...

Hejazizadeh, Z.; Naserzadeh, M. H.

2007-01-01

362

[Temperature conditions of the formation of frost damages in conifer trees in the high latitudes of Western Siberia].  

Science.gov (United States)

Frost damage to the bottom of the stem at a height of 0.2 m and at the height of the position of the thermometer in the weather station (2 m) and higher in the Siberian spruce (Picea obovata Ledeb.) and Siberian larch (Larix sibirica Ledeb.) growing at the northern limits of their natural habitat were studied in order to reveal the upper threshold temperature conditions of their formation. Possible causes of differences in the distribution of frost damage in the stem of the spruce and larch are discussed. PMID:25735171

Gurskaia, M A

2014-01-01

363

Frost-acclimation of photosynthesis in overwintering Mediterranean holm oak, grown in Central Europe  

Directory of Open Access Journals (Sweden)

Full Text Available As a consequence of global change, forestry in Central Europe has to expect and be prepared for an increase of hot and dry summers in the near future. In two model plantations of the Mediterranean holm oak (Quercus ilex L. in Central Europe (Rhine-Main basin we tested its potential as a future forestry tree for drought-threatened stands by studying its overwintering strategy under harsh winter conditions. During prolonged frost periods, chronic photoinhibition was developed, which lasted until the end of the frost period. Nearly all plants survived minimum temperatures of - 16 to -18°C and their photosynthetic apparatus recovered completely during late winter. A detailed study of the temperature dependence of chlorophyll (chl fluorescence parameters of the OJIP test revealed statistically significant correlations between minimum temperature and maximum quantum yield of primary photochemistry (Fv/Fm, absorption rate/reaction centre (ABS/RC, dissipation rate/reaction centre (DI0/RC and electron transport rate/reaction centre (ET0/RC as well as with the deepoxidation state (DES of the xanthophyll pigments. The DES correlated with Fv/Fm, ABS/RC, DI0/RC and ET0/RC. It is concluded, that from the point of view of the winter hardiness of the photosynthetic apparatus, Q. ilex should be further investigated as a potential future forestry tree also for very dry and warm stands in Central Europe under the scenarios of climate change.

Ellen Pflug

2012-03-01

364

ASSESSMENT OF CERAMIC TILE FROST RESISTANCE BY MEANS OF THE FREQUENCY INSPECTION METHOD  

Directory of Open Access Journals (Sweden)

Full Text Available The paper presents some results of our experimental analysis of ceramic cladding element frost resistance, particular attention being paid to the application of the frequency inspection method. Three different sets of ceramic tiles of the Ia class to EN 14 411 B standard made by various manufacturers have been analyzed. The ceramic tiles under investigation have been subjected to freeze-thaw-cycle-based degradation in compliance with the relevant ?SN EN ISO 10545-12 standard. Furthermore, accelerated degradation procedure has been applied to selected test specimens, consisting in reducing the temperature of water soaked ceramic tiles in the course of the degradation cycles down –70°C. To verify the correctness of the frequency inspection results, additional physical properties of the ceramic tiles under test have been measured, such as, the ceramic tile strength limit, modulus of elasticity and modulus of deformability, resulting from the flexural tensile strength tests, integrity defect and surface micro-geometry tracking. It has been proved that the acoustic method of frequency inspection is a sensitive indicator of the structure condition and can be applied to the ceramic cladding element frost resistance and service life prediction assessment.

MICHAL MATYSÍK

2011-06-01

365

Frost Growth and Densification on a Flat Surface in Laminar Flow with Variable Humidity  

Science.gov (United States)

Experiments are performed concerning frost growth and densification in laminar flow over a flat surface under conditions of constant and variable humidity. The flat plate test specimen is made of aluminum-6031, and has dimensions of 0.3 mx0.3 mx6.35 mm. Results for the first variable humidity case are obtained for a plate temperature of 255.4 K, air velocity of 1.77 m/s, air temperature of 295.1 K, and a relative humidity continuously ranging from 81 to 54%. The second variable humidity test case corresponds to plate temperature of 255.4 K, air velocity of 2.44 m/s, air temperature of 291.8 K, and a relative humidity ranging from 66 to 59%. Results for the constant humidity case are obtained for a plate temperature of 263.7 K, air velocity of 1.7 m/s, air temperature of 295 K, and a relative humidity of 71.6 %. Comparisons of the data with the author's frost model extended to accommodate variable humidity suggest satisfactory agreement between the theory and the data for both constant and variable humidity.

Kandula, M.

2012-01-01

366

The FROST code for predicting in-reactor behaviours of LWR fuel rod  

International Nuclear Information System (INIS)

FROST (Fuel Rod Stress Analysis) is a computor code which analyzes irradiation behaviours - especially the stresses and strains - of a fuel rod for LWR. The handling of dynamics of the code is essentially based on well-known CYGRO code which deals with one axial segment of a rod. However, the capability of FROST has further been extended so that it could handle the axial variation effect such as axial power shape, fission gas pressure and axial PCI by applying the above one-segmental mechanics to all the axial segments of a rod. In addition, most of the models describing the phenomena were replaced by relatively recent LWR based correlations. In this code, a fuel rod is divided into desired number of axial segments and radial rings for both pellet and clad. Every phenomenon occurring in an elementary ring is reduced to the dimensional change of the ring, and the overall deformation of one axial segment is calculated by using the finite element method. Then all the segments are axially connected together with a plenum to calculate fission gas pressure and axial PCI. The latter is done by newly developed axial interaction model which can deal with the plenum spring and pellet-pellet axial gaps, in addition to the usual mechanisms of sticking and slipping. These procedures are repeated following the irradiation history, and in the course of them, the deformations, stresses, strains and the other phenomena are calculated. (orig.)

367

Pumping of gaseous helium using argon frosted liquid helium cryo-condensation pumps  

International Nuclear Information System (INIS)

It has been demonstrated in the Neutral Injection Test Bed that the JET neutral injectors are capable of producing 10 s He beams repetitively with a rate of 7 min per shot without a prohibitive pressure rise. This can be achieved without modifications to the JET liquid helium (LHe) cryo-condensation pumps. The He is pumped by cryo-sorption on Ar, which is frosted onto the LHe temperature panels before each pulse. The measured effective pumping speed is about 0.25 times the value for H2. The measurements involved 3 cryo-pumps, 2 of the JET open structure type and one with a conventional type of liquid nitrogen (LN2) cooled baffle. The tests show that the Ar/He coverage ratio and the thickness of the Ar layer seem to be important. The sticking coefficients for He on Ar frost derived for the 3 pumps agree with each other within the errors. 8 refs., 6 figs., 1 tab

368

Zwitter-wettability and antifogging coatings with frost-resisting capabilities.  

Science.gov (United States)

Antifogging coatings with hydrophilic or even superhydrophilic wetting behavior have received significant attention due to their ability to reduce light scattering by film-like condensation. However, under aggressive fogging conditions, these surfaces may exhibit frost formation or excess and nonuniform water condensation, which results in poor optical performance of the coating. In this paper, we show that a zwitter-wettable surface, a surface that has the ability to rapidly absorb molecular water from the environment while simultaneously appearing hydrophobic when probed with water droplets, can be prepared by using hydrogen-bonding-assisted layer-by-layer (LbL) assembly of poly(vinyl alcohol) (PVA) and poly(acrylic acid) (PAA). An additional step of functionalizing the nano-blended PVA/PAA multilayer with poly(ethylene glycol methyl ether) (PEG) segments produced a significantly enhanced antifog and frost-resistant behavior. The addition of the PEG segments was needed to further increase the nonfreezing water capacity of the multilayer film. The desirable high-optical quality of these thin films arises from the nanoscale control of the macromolecular complexation process that is afforded by the LbL processing scheme. An experimental protocol that not only allows for the exploration of a variety of aggressive antifogging challenges but also enables quantitative analysis of the antifogging performance via real-time monitoring of transmission levels as well as image distortion is also described. PMID:23360374

Lee, Hyomin; Alcaraz, Maria L; Rubner, Michael F; Cohen, Robert E

2013-03-26

369

Warming in the Yukon River Basin is Likely to Release Substantial Amounts of Soil Organic Carbon  

Science.gov (United States)

In recent decades the Yukon River Basin (YRB) in northwestern Canada and central Alaska has experienced a substantial warming trend resulting in a variety of geophysical and biological responses. Climatologic measurements consistent with rapid warming in the YRB during the last several decades of the 20th century include surface air temperature (especially daily minima), number of frost-free days, and the number of very warm days. During the 20th century daily maxima in the warm season in the YRB have increased only weakly, and modest autumn cooling occurred. Indirect indicators of warming include shrinkage in lake area, decreases in glacier mass, increased fire frequency and annual area burned, and changes in permafrost thickness and permafrost temperature. Changes in tree growth rates and susceptibility to pests have been related to warming and drying in interior Alaska. Oral histories of Alaska Natives have also revealed many other warming related changes in the YRB. If ongoing warming trends continue there is a concern that large stores of soil organic carbon (SOC) will be at risk for release to the atmosphere through heterotrophic decomposition. Warming tends to accelerate microbial decomposition at a faster rate than net primary productivity. One of the most important effects of warming in the YRB is likely to be its influence on the hydrologic and cryospheric regimes. Warming may be accompanied by soil drying and lowering of the water table in wetlands and lakes exposing more SOC to aerobic decomposition. A substantial portion of the YRB is underlain by permafrost that thaws to a variable depth (active layer) each summer. Increasing the thickness of the active layer exposes more SOC to microbial decomposition. Increasing the burned area results in direct SOC losses by oxidation during the fire and decreases albedo that warms surface soils and increases the thickness of the active layer. Warming and increasing length of the growing season increases seasonal evapotranspiration and results in enhanced soil drying and lowering of the water table. Warming decreases tree growth rates on many sites, triggers insect defoliation, and causes widespread fires which all decrease aboveground organic inputs to soils. Warmer and drier conditions are likely to result in a reduction in the area of black spruce that would likrly act to reduce future fire frequency. Changes in forest species composition towards assemblages adapted to a warmer and drier climate and the possible introduction of earthworms could result in losses of SOC.

Juday, G. P.; Huntington, T. G.

2005-12-01

370

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

Science.gov (United States)

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

371

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

Science.gov (United States)

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

372

Peripheral capillary nonperfusion and full-field electroretinographic changes in eyes with frosted branch-like appearance retinal vasculitis  

Directory of Open Access Journals (Sweden)

Full Text Available Yoshitsugu Matsui, Hideyuki Tsukitome, Eriko Uchiyama, Yuko Wada, Tatsuya Yagi, Hisashi Matsubara, Mineo KondoDepartment of Ophthalmology, Mie University Graduate School of Medicine, Tsu, JapanAbstract: We report a patient with frosted branch-like appearance retinal vasculitis associated with peripheral capillary nonperfusion and full-field electroretinographic changes. A 62-year-old man presented with sudden bilateral decreased vision accompanied by headaches. His best-corrected visual acuity was 0.01 in both eyes. Fundus examination and fluorescein angiography showed bilateral frosted branch-like appearance retinal vasculitis, and spectral-domain optical coherence tomography showed severe macular edema in both eyes. The cerebrospinal fluid analyses showed an increased lymphocyte count and protein levels. He was treated with systemic corticosteroid therapy, and his best-corrected visual acuity improved to 0.8 OD and 1.0 OS at 6 months after onset. However, fluorescein angiography showed a lack of capillary perfusion in the periphery, and the oscillatory potentials on full-field electroretinography were severely reduced in both eyes. These findings indicated extensive retinal ischemia and inner retinal dysfunction, and that fluorescein angiography and full-field electroretinograms can be useful during follow-up of eyes with frosted branch-like appearance retinal vasculitis.Keywords: frosted branch angiitis, aseptic meningitis, optical coherence tomography, electroretinogram, oscillatory potentials

Matsui Y

2013-01-01

373

Molecular ennoblement of frost tolerance and phenology in Salix. Final report; Molekylaer foeraedling av frostresistens och fenologi i Salix. Slutrapport  

Energy Technology Data Exchange (ETDEWEB)

Two Salix genetic linkage maps have been produced. One is based on a cross between a S.viminalis clone (78183) and a S. viminalis x S. schwerinii hybrid (Bjoern), the second on a cross between Jorunn (S. viminalis) and a russian clone (SW1290). Both crosses have been utilised in field and greenhouse experiments to map genes affecting important traits. QTLs for growth related traits were mapped using the 78182xBjoern cross in one field trial measured during four years. QTLs with relatively large effects were detected for several traits, but the stability of the QTLs over years was limited. Extensive artificial frost resistance experiments with the second cross identified several genes (QTLs) affecting frost tolerance. Frost tolerance genes were identified before the start of the acclimation process, but they were replaced by other genes later during the acclimation process. The results support that frost tolerance is a complex process controlled by a large number of genes. An initial resistance is controlled by genes different from those that are important during the acclimation process.

Lagercrantz, U. [Swedish Univ. of Agricultural Sciences, Uppsala (Sweden). Dept. of Plant Biology

2001-09-01

374

Evaluation of the occurence of agricultural frost in state of Parana, Brazil, generated by a regional forecast model  

Science.gov (United States)

This study evaluated the potential use of a regional atmospheric model to predict the occurrence of agricultural frost three days in advance, as based on the vulnerability to low temperatures of the main crops in eight locations in the state of Parana, Brazil, between 2000 and 2007. Based on the reported occurrence of frosts, the values of the air temperature observed at meteorological stations were compared with the 66 h advance predictions obtained by the model. In general, we observed a slight overestimation of the air temperature values for all of the locations during the frost events. However, regression analyses demonstrated a good quality of the prediction of the model despite the data grid being relatively coarse. The coefficients of determination (R2) were larger than 0.65, whereas the systematic errors varied between 0.26 and 0.69°C, and the magnitude of error does not exceed 1.7°C. The hit rates of the categorical forecasts showed that the temperature 66 hours in advance was adequate to detect the occurrence of frost because the accuracy of forecasting exceeded 0.80, the probability of detection reached 0.70, and the false alarm rate did not exceeded 0.3.

Giarolla, Angelica; Chou, Sin C.; Faria, Rogerio T.

2013-04-01

375

REDES NEURONALES PARA MODELAR PREDICCIÓN DE HELADAS Neural networks for modeling frost prediction  

Directory of Open Access Journals (Sweden)

Full Text Available En este trabajo se desarrollaron modelos basados en redes neuronales del tipo "backpropagation", para predecir la ocurrencia de heladas, a partir de datos meteorológicos de temperatura, humedad relativa, nubosidad, dirección y velocidad del viento. El entrenamiento y la validación de las redes se realizaron utilizando 24 años de datos meteorológicos correspondientes a la estación de Río Cuarto, Córdoba, Argentina, separados en 10 años como conjunto de datos de entrenamiento y 14 como conjunto de datos de validación. Se construyeron diferentes modelos para evaluar el comportamiento de las redes cuando se usan distintos números de variables de entrada y/o neuronas en la capa oculta y las probabilidades de aciertos en los resultados de predicción para los mismos, al considerar distintas variables de entrada. En los modelos realizados, el porcentaje de días con error de pronóstico fue de 2%, aproximadamente, para 14 años de aplicación; cuando se consideran días de heladas efectivas no pronosticadas los porcentajes oscilan entre un 10% y un 23%, para el mismo período. Los resultados de la simulación muestran el buen desempeño y la pertinencia general de esta metodología en la estimación de fenómenos de comportamiento no lineal como las heladasIn this work models based on neural networks of the backpropagation type were developed in order to predict the occurrence of frosts from meteorological data such as temperature, relative humidity, cloudiness and wind direction and speed. The training and the validation of the networks were made on the basis of 24 years of meteorological data corresponding to the Río Cuarto station, Córdoba, Argentina. These data were grouped as follows: 10 years for the training data set and 14 years for the validation data set. Different models were built to evaluate the performance of the networks when different numbers of input variables and/or neurons in the hidden layer are used, and the probabilities of success in the prediction results on considering different input variables. In the models used, the percentage of days with prediction error was 2%, approximately, for the 14 years of application; when effective frosts days are considered the percentage varies between 10 and 23%, for the same period. The simulation results demonstrated the good performance and the relevance of this methodology for the estimation of the behavior of non-linear phenomena like frosts.

Gustavo Ovando

2005-03-01

376

Research on frost formation in air source heat pump at cold-moist conditions in central-south China  

International Nuclear Information System (INIS)

Highlights: ?A dynamic evaporator model is built up. ? The model involves the ratio of the latent heat to sensible heat of wet air. ?A correlation considering deq is shown below to predict frost accumulation: (Mfrv3)/(?deq2) =((Ta)/(Tw) )0.1((v?)/(deq) )0.7(l/(deq) )1.378Xa1.228. ?The changing ratio can characterize the early development of system performance. ?The changing ratio can characterize the early development of frost accumulation. -- Abstract: A dynamic evaporator model of air source heat pump (ASHP), considering the ratio of the latent heat to sensible heat of wet air, is presented to analyze the performance of ASHP under frosting. The performance parameters, such as the heating capacity, COP and the outlet temperature of compressor, are simulated with CYCLEPAD. Then a semi-empirical correlation that predicts frost accumulation on the air-side of fin-tube heat exchanger is developed with dimensionless analysis and also modified by a test conducted under cold-moist conditions in winter. In addition, eight influence factors are considered involving the ambient conditions and structures of heat exchanger, whose effects are analyzed as well. Among them, the equivalent diameter of air flow cross-section in fin-tube deq is especially proposed. Lastly, the relationships between the ratio, the performance parameters and the frost accumulation are discussed in this paper, followed by an evaluation of an optimal defrosting time interval to improve the ASHP’s energy efficiency and operational reliability at cold-moist conditions in central-south China.

377

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

Energy Technology Data Exchange (ETDEWEB)

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

378

Jet impingement heat transfer in a frost-free refrigerator: The influence of confinement  

Energy Technology Data Exchange (ETDEWEB)

Heat transfer characteristics of a slot air jet (width w) impinging on a circular cylinder (diameter d = w) located 5d from the jet exit in a confined space have been studied for Reynolds number (based on cylinder diameter and mean jet velocity) in the range of 1000-12,000. This situation is found in a frost-free refrigerator, amongst other rapid food refrigeration applications. The results reveal that the slot jet impinging on a circular cylinder in a confined space yields heat transfer rates that are between those for the corresponding uniform cross-flow (lower limit) and slot jet impingement on a non-confined cylinder (upper limit) cases. A dimensionless confinement spacing H/d = 10 was found at which the heat transfer rate was a minimum. CFD analysis revealed that this was due to periodic jet flapping and generation of large flow structures between the cylinder and the confining wall. (author)

Imraan, M.; Sharma, R.N. [Department of Mechanical Engineering, The University of Auckland, 20 Symonds Street, Private Bag 92019, Auckland (New Zealand)

2009-05-15

379

Frost protection for wind energy installations; Frostschutz fuer Windenergieanlagen. Eisfreie Oberflaechen der Natur abgeschaut  

Energy Technology Data Exchange (ETDEWEB)

This article discusses how naidered intural materials can be used to prevent wind energy installations in exposed alpine locations from icing up. The problems encountered with wind turbines in Scandinavia and in the Swiss Alps due to icing-up are discussed. The mechanisms involved in the formation of hoar frost and clear ice on the rotors of the wind turbines are discussed. Techniques and materials for fighting the icing-up of the rotors are examined. Various special 'ice-phobic' coatings for the rotor blades are listed and discussed. These must adhere to the rotor blades but be repellent to ice. Teflon is quoted as being the most tested material. So-called 'anti-freeze' proteins that can be found in fish and insects are also being examined as a possible coating for the rotors.

Siegmann, K.; Meola, G.; Hirayama, M.

2009-07-01

380

Evolution of the N2 frost distribution on Triton during thousands of terrestrial years  

Science.gov (United States)

Previously, we have built a 3D model of Triton's atmosphere [11]. This GCM based on a high thermal inertia of the substrate material [9] and the presence of a polar cap in the South and an unfrosted equatorial band [7], manages to reconcile the different observations of Voyager 2 : retrograde surface winds, prograde winds at 8 km, temperature profiles... This elevated thermal inertia allows to keep the heat of the equatorial band during a sufficiently long time and to introduce a phase lag into the seasonal cycle. On the basis of this 3D model, we have built a 2D model which predicts the evolution of the distribution of Triton's N2 frost over thousands of years. These results are compared with observations and former models[5,6].

Vangvichith, M.; Forget, F.

2011-10-01

381

Results of the radiological survey at 15 Frost Place, Albany, New York  

International Nuclear Information System (INIS)

A number of properties in the Albany/Colonie area have been identified as being potentially contaminated with uranium originating from the former National Lead Company's uranium forming plant in Colonie, New York. The property at 15 Frost Place in Albany, New York, was the subject of a radiological investigation initiated July 22, 1986. The residential property consists of a two-story frame house with a separate garage located on a rectangular lot. An asphalt driveway connects the garage to the street. A diagram of the property showing the approximate boundaries and the 5-m grid network established for measurements outside the house is shown. The lot included in the radiological survey was /approximately/ 16 m wide by 33 m deep. Front and rear views of the property are shown. 13 refs., 5 figs., 5 tabs

382

Hydrogen frosting scenarios with the ASDEX upgrade in-vessel cryo pump  

International Nuclear Information System (INIS)

The ASDEX upgrade vacuum vessel is equipped with 14 turbo molecular pumps (TMPs) and a cryo pump (CP). The CP is cooled with boiling helium (He). To obtain similar conditions with the CP for hydrogen (H2) and deuterium (D2) pumping a lower helium panel temperature (THP) is required in the case of H2. This is achieved by reducing the He boiling pressure (pb) and thus the He boiling temperature (Tb) via pump down of the He cryostat. The requirements are predicted by computations and verified experimentally for this case. By raising the cryostat pressure above ambient, the prediction of the H2 end pressure (peH2) of the CP could be compared with measurements in the range 5x10-7eH2 (mbar)-4. The beneficial effect of argon frosting for helium pumping is only shown experimentally

383

Frost resistance of building materials : Modelling of critical degrees of saturation  

DEFF Research Database (Denmark)

In this thesis it is shown that the critical degree of saturation is suitable as parameter for the frost resistance of porous building materials. A numerical model for prediction of critical degrees of saturation based on fracture mechanics and phase geometry of two-phase materials, e.g. porous materials, has been developed.The importance of the pore structure on the development of stresses in the material during freezing is emphasized. To verify the model, experimental investigations are made on various concretes without air-entrainment and brick tiles with different porosities.Calculations of critical degrees of saturation are compared with experimentally determined values and results from standardised freeze-thaw tests. Based on these results, the model, its mode of operation and the conditions of the model is analysed and discussed.Appendices and description of supplementary tests are placed in separate volumes.

Hansen, Ernst Jan De Place

1996-01-01

384

Electrical heating tapes for hot water piping and frost protection; Elektrische Heizbaender fuer Warmwasserleitungen und Frostschutz  

Energy Technology Data Exchange (ETDEWEB)

This leaflet issued by the Swiss Federal Office of Energy and professional plumbing and installation associations presents information and recommendations on the use of electrical heating tapes in sanitary installations and rainwater piping. The considerable amount of electrical power needed for the operation of these heating tapes is discussed and methods of reducing consumption by the use efficient controllers are described. It is further mentioned that the correct design and planning of sanitary installations can help reduce the necessity for the use of heating tapes. Cost comparisons are made between heat-tape and circulation-based solutions for different heat sources. Tips are provided on installation details. Frost protection for piping in unheated rooms and for rainwater down-pipes is also discussed.

Nipkow, J.

2003-07-01

385

An investigation of periglacial slope stability in relation to soil properties based on physical modelling in the geotechnical centrifuge  

Science.gov (United States)

Results are presented from eight scaled centrifuge modelling experiments designed to investigate mass movement processes on thawing ice-rich slopes. Four pairs of simple planar slope models were constructed, one in each pair being of sufficient gradient to promote slope failure during soil thaw and the second having a gradient below the threshold for instability. Four frost susceptible soils were used, three were normally consolidated and had different clay contents (2%, 12% and 20%) and the fourth comprised the 20% clay soil, but was over consolidated prior to model testing. Modelling protocols included freezing from the surface downwards under an open hydraulic system, and thawing from the surface downwards under an enhanced gravitational field within the geotechnical centrifuge, thereby utilising scaling laws to simulate correct prototype self weight stresses during thaw. Slopes below the stability threshold gradient were subjected to between 2 and 4 cycles of freezing and thawing, simulating annual cycles. Those above the stability threshold were subjected to only one cycle, since they failed during the first thaw phase. Thermal conditions, pore water pressures, surface movements, and profiles of displacement are reported. Measured pore pressures are used in slope stability analyses based on a simple planar infinite slope model. Profiles of solifluction shear strain and mechanisms of slope failure are both shown to be sensitive to small changes in soil properties, particularly clay content and stress history. In all cases, pore pressures rose rapidly immediately following thaw, remained below the threshold for failure in low gradient models, but exceeding the threshold to trigger landslides on steeper slopes. Upward seepage of melt water away from the thaw front contributed to loss of shear strength. Mechanisms of slope failure differed between test soils, ranging from mudflow in non-cohesive silt to active layer detachment sliding in over consolidated silt-clay. During solifluction, shear strain was greatest at the surface in non-cohesive silt and decreased rapidly with depth, but in test soils containing clay, the zone of maximum shear strain was located lower in the displacement profiles.

Harris, Charles; Smith, James S.; Davies, Michael C. R.; Rea, Brice

2008-01-01

386

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

Science.gov (United States)

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

387

Numerical analysis of the impact of charcoal production on soil hydrological behavior, runoff response and erosion susceptibility Investigação numérica/quantitativa sobre o impacto do processo de produção de carvão nas propriedades hidráulicas, resposta ao deflúvio e suscetibilidade do solo à erosão  

Directory of Open Access Journals (Sweden)

Full Text Available The impact of charcoal production on soil hydraulic properties, runoff response and erosion susceptibility were studied in both field and simulation experiments. Core and composite samples, from 12 randomly selected sites within the catchment of Kotokosu were taken from the 0-10 cm layer of a charcoal site soil (CSS and adjacent field soils (AFS. These samples were used to determine saturated hydraulic conductivity (Ksat, bulk density, total porosity, soil texture and color. Infiltration, surface albedo and soil surface temperature were also measured in both CSS and AFS. Measured properties were used as entries in a rainfall runoff simulation experiment on a smooth (5 % slope plot of 25 x 25 m grids with 10 cm resolutions. Typical rainfall intensities of the study watershed (high, moderate and low were applied to five different combinations of Ks distributions that could be expected in this landscape. The results showed significantly (p O impacto do processo de produção de carvão nas propriedades hidráulicas, a resposta ao deflúvio e a suscetibilidade do solo à erosão foram estudados em experimentos de campo e de simulação. Amostras indeformadas e compostas de 12 locais aleatoriamente selecionados dentro do reservatório de Kotokosu foram coletadas na camada de 0-10 cm no solo sob carvão (CSS e no solo adjacente (AFS. Essas amostras foram usadas para determinar a condutividade hidráuli7ca saturada (Ksat, densidade do solo, porosidade total, textura e cor do solo. A infiltração, o albedo de superfície e a temperatura de superfície do solo também foram medidos no CSS e AFS. Os parâmetros medidos foram usados como entrada nos experimentos de simulação de deflúvio em uma parcela uniforme (5 % de declividade de 25 x 25 m, com grides de 10 cm de resolução. Altas, moderadas e baixas intensidades de chuva, típicas da bacia em estudo, foram aplicadas em cinco diferentes combinações de Ksat, que poderiam ser esperadas nessa paisagem. Os resultados mostraram que as características do fluxo do solo sob carvão aumentaram significativamente (p < 0,01 em 88 %. A infiltração foi aumentada e o volume de deflúvio reduzido significativamente. Houve redução no deflúvio em torno de 37 e 18 %, e o coeficiente de deflúvio variou de 0,47-0,75 e 0,04 a 0,39 para a simulação de chuvas de alta (200 mm h-1 e moderada (100 mm h-1 intensidades nas condições CSS e AFS, respectivamente. Outros impactos em potencial da produção de carvão na bacia hidrológica foram observados. Espera-se que, com os resultados aqui apresentados, além dos determinados na bacia, quando disponíveis, haja uma compreensão melhor das respostas hidrológicas do ecossistema de fabricação indiscriminada de carvão e de outras atividades relacionadas nessa região.

Ajayi Ayodele

2009-02-01

388

An improved scheme for classifying susceptibility to preferential flow  

Science.gov (United States)

The ability to reliably predict the occurrence and strength of preferential flow in different soils and land use systems would be of great benefit in environmental planning and management at multiple spatial scales, from field to catchments and regions. We recently proposed a simple classification scheme for predicting the susceptibility of soil horizons and pedons to macropore flow, designed to support predictive modelling (Jarvis N.J. et al., 2009. A conceptual model of soil susceptibility to macropore flow. Vadose Zone Journal, 8: 902-910). The scheme, which takes the form of a decision tree, was successfully validated against a small dataset of solute transport experiments. However, in its present form, it is strongly biased toward European agricultural soils, since it was developed to support pesticide risk assessment in the EU. In this poster, we propose an improved version of the classification scheme, which is much broader in scope, with relevance for a much wider range of soils worldwide, including those with clay mineralogies that limit the development of soil macro-structure and restrict macropore flow (e.g. Ferralsols and Andosols). The new scheme is tested in a literature meta-analysis exercise, making use of the temporal moments of solute breakthrough curves derived from fits of the mobile / immobile model to steady-state experiments on short laboratory columns.

Moeys, Julien; Koestel, John; Hollis, John M.; Jarvis, Nicholas J.

2010-05-01

389

Alate susceptibility in ants.  

Science.gov (United States)

Pathogens are predicted to pose a particular threat to eusocial insects because infections can spread rapidly in colonies with high densities of closely related individuals. In ants, there are two major castes: workers and reproductives. Sterile workers receive no direct benefit from investing in immunity, but can gain indirect fitness benefits if their immunity aids the survival of their fertile siblings. Virgin reproductives (alates), on the other hand, may be able to increase their investment in reproduction, rather than in immunity, because of